Design Resources Online Documentation Dual, 14-Bit, 1.25 GSPS, 1.2 V/2.5 V, Analog-to-Digital Converter AD9680 FEATURES APPLICATIONS Communications Diversity multiband, multimode digital receivers 3G/4G, TD-SCDMA, W-CDMA, GSM, LTE General-purpose software radios Ultrawideband satellite receivers Instrumentation Radars Signals intelligence (SIGINT) DOCSIS 3.0 CMTS upstream receive paths HFC digital reverse path receivers BUFFER FD_A ADC CORE 14 FD_B DDC SIGNAL MONITOR 14 VIN+B VIN–B DDC ADC CORE BUFFER CONTROL REGISTERS V_1P0 SIGNAL MONITOR CLOCK GENERATION CLK+ CLK– ÷2 ÷4 ÷8 AGND DRGND DGND 4 FAST DETECT JESD204B SUBCLASS 1 CONTROL SPI CONTROL AD9680 SDIO SCLK CSB SERDOUT0± SERDOUT1± SERDOUT2± SERDOUT3± SYNCINB± SYSREF± PDWN/ STBY 11752-001 VIN+A VIN–A FAST DETECT JESD204B (Subclass 1) coded serial digital outputs 1.65 W total power per channel at 1 GSPS (default settings) SFDR at 1 GSPS = 85 dBFS at 340 MHz, 80 dBFS at 1 GHz SNR at 1 GSPS = 65.3 dBFS at 340 MHz (AIN = −1.0 dBFS), 60.5 dBFS at 1 GHz (AIN = −1.0 dBFS) ENOB = 10.8 bits at 10 MHz DNL = ±0.5 LSB INL = ±2.5 LSB Noise density = −154 dBFS/Hz at 1 GSPS 1.25 V, 2.5 V, and 3.3 V dc supply operation No missing codes Internal ADC voltage reference Flexible input range: 1.46 V p-p to 1.94 V p-p AD9680-1250: 1.58 V p-p nominal AD9680-1000 and AD9680-820: 1.70 V p-p nominal AD9680-500: 1.46 V p-p to 2.06 V p-p (2.06 V p-p nominal) Programmable termination impedance 400 Ω, 200 Ω, 100 Ω, and 50 Ω differential 2 GHz usable analog input full power bandwidth 95 dB channel isolation/crosstalk Amplitude detect bits for efficient AGC implementation 2 integrated wideband digital processors per channel 12-bit NCO, up to 4 half-band filters Differential clock input Integer clock divide by 1, 2, 4, or 8 Flexible JESD204B lane configurations Small signal dither FUNCTIONAL BLOCK DIAGRAM SPIVDD AVDD1 AVDD2 AVDD3 AVDD1_SR DVDD DRVDD (1.25V) (1.25V) (1.25V) (1.8V TO 3.3V) (1.25V) (2.5V) (3.3V) Tx OUTPUTS Data Sheet Sample & Buy Discussion JESD204B HIGH SPEED SERIALIZER Product Overview Figure 1. PRODUCT HIGHLIGHTS 1. 2. 3. 4. 5. 6. Wide full power bandwidth supports IF sampling of signals up to 2 GHz. Buffered inputs with programmable input termination eases filter design and implementation. Four integrated wideband decimation filters and numerically controlled oscillator (NCO) blocks supporting multiband receivers. Flexible serial port interface (SPI) controls various product features and functions to meet specific system requirements. Programmable fast overrange detection. 9 mm × 9 mm, 64-lead LFCSP. Rev. C Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2014–2015 Analog Devices, Inc. All rights reserved. Product Overview Design Resources Online Documentation AD9680 Discussion Sample & Buy Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Frequency Translation General Description .............................. 54 Applications ....................................................................................... 1 DDC NCO Plus Mixer Loss and SFDR ................................... 55 Functional Block Diagram .............................................................. 1 Numerically Controlled Oscillator .......................................... 55 Product Highlights ........................................................................... 1 FIR Filters ........................................................................................ 57 Revision History ............................................................................... 3 FIR Filters General Description ............................................... 57 General Description ......................................................................... 4 Half-Band Filters ........................................................................ 58 Specifications..................................................................................... 5 DDC Gain Stage ......................................................................... 60 DC Specifications ......................................................................... 5 DDC Complex to Real Conversion ......................................... 60 AC Specifications.......................................................................... 6 DDC Example Configurations ................................................. 61 Digital Specifications ................................................................... 8 Digital Outputs ............................................................................... 64 Switching Specifications .............................................................. 9 Introduction to the JESD204B Interface ................................. 64 Timing Specifications ................................................................ 10 JESD204B Overview .................................................................. 64 Absolute Maximum Ratings .......................................................... 12 Functional Overview ................................................................. 65 Thermal Characteristics ............................................................ 12 JESD204B Link Establishment ................................................. 65 ESD Caution ................................................................................ 12 Physical Layer (Driver) Outputs .............................................. 67 Pin Configuration and Function Descriptions ........................... 13 JESD204B Tx Converter Mapping ........................................... 69 Typical Performance Characteristics ........................................... 15 Configuring the JESD204B Link .............................................. 71 AD9680-1250 .............................................................................. 15 Multichip Synchronization............................................................ 74 AD9680-1000 .............................................................................. 19 SYSREF± Setup/Hold Window Monitor ................................. 76 AD9680-820 ................................................................................ 24 Test Modes ....................................................................................... 78 AD9680-500 ................................................................................ 29 ADC Test Modes ........................................................................ 78 Equivalent Circuits ......................................................................... 33 JESD204B Block Test Modes .................................................... 79 Theory of Operation ...................................................................... 35 Serial Port Interface ........................................................................ 81 ADC Architecture ...................................................................... 35 Configuration Using the SPI ..................................................... 81 Analog Input Considerations.................................................... 35 Hardware Interface ..................................................................... 81 Voltage Reference ....................................................................... 41 SPI Accessible Features .............................................................. 81 Clock Input Considerations ...................................................... 42 Memory Map .................................................................................. 82 ADC Overrange and Fast Detect .................................................. 44 Reading the Memory Map Register Table............................... 82 ADC Overrange .......................................................................... 44 Memory Map Register Table ..................................................... 83 Fast Threshold Detection (FD_A and FD_B) ........................ 44 Applications Information .............................................................. 96 Signal Monitor ................................................................................ 45 Power Supply Recommendations............................................. 96 SPORT Over JESD204B ............................................................. 46 Exposed Pad Thermal Heat Slug Recommendations ............ 96 Digital Downconverter (DDC) ..................................................... 48 AVDD1_SR (Pin 57) and AGND (Pin 56 and Pin 60) .............. 96 DDC I/Q Input Selection .......................................................... 48 Outline Dimensions ....................................................................... 97 DDC I/Q Output Selection ....................................................... 48 Ordering Guide .......................................................................... 97 DDC General Description ........................................................ 48 Frequency Translation ................................................................... 54 Rev. C | Page 2 of 97 Product Overview Design Resources Online Documentation Discussion Data Sheet Sample & Buy AD9680 REVISION HISTORY 11/15—Rev. B to Rev. C Added AD9680-1250 ......................................................... Universal Changes to Features Section ............................................................ 1 Change to General Description Section ......................................... 4 Changes to Table 1 ............................................................................ 5 Changes to Table 2 ............................................................................ 6 Changes to Table 4 ............................................................................ 9 Changes to Table 5 ..........................................................................10 Changes to Figure 4.........................................................................11 Changes to Pin 14 Description, Table 8 .......................................14 Added AD9680-1250 Section and Figure 6 to Figure 29; Renumbered Sequentially ..............................................................15 Changes to Figure 113 ....................................................................34 Changes to Analog Input Considerations Section ......................35 Changes to Table 9 ..........................................................................36 Changes to Input Buffer Control Registers (0x018, 0x019, 0x01A, 0x935, 0x934, 0x11A) Section ..........................................37 Added Figure 118 to Figure 120 ....................................................37 Changes to Table 10 ........................................................................40 Changes to Table 17 ........................................................................57 Changes to ADC Test Modes Section ...........................................78 Changes to Table 36 ........................................................................83 Changes to Ordering Guide ...........................................................97 3/15—Rev. A to Rev. B Added AD9680-820 ........................................................... Universal Changes to Features Section ............................................................ 1 Changes to Table 1 ............................................................................ 5 Changes to Table 2 ............................................................................ 6 Changes to Table 3 ............................................................................ 8 Changes to Table 4 ............................................................................ 9 Added Figure 14; Renumbered Sequentially ...............................15 Added AD9680-820 Section and Figure 31 Through Figure 36 ...19 Added Figure 37 Through Figure 42 ............................................20 Added Figure 43 Through Figure 48 ............................................21 Added Figure 49 Through Figure 54 ............................................22 Added Figure 55 ..............................................................................23 Changes to Figure 69 and Figure 70 .............................................26 Changes to Input Buffer Control Registers (0x018, 0x019, 0x01A, 0x935, 0x934, 0x11A) Section, Table 9, and Figure 93....................31 Added Figure 99 Through Figure 100 ..........................................33 Changes to Table 10 ........................................................................34 Changes to Clock Jitter Considerations Section .........................37 Added Figure 112 ............................................................................37 Changes to Digital Downconverter (DDC) Section ...................42 Changes to Table 17 ........................................................................51 Changes to Table 36 ........................................................................77 Changes to Ordering Guide ...........................................................91 12/14—Rev. 0 to Rev. A Added AD9680-500 ........................................................... Universal Changes to Features Section and Figure 1 ..................................... 1 Changes to General Description Section ....................................... 4 Changes to Specifications Section and Table 1 ............................. 5 Changes to AC Specifications Section and Table 2....................... 6 Changes to Digital Specifications Section ..................................... 8 Changes to Switching Specifications Section and Table 4 ........... 9 Changes to Table 6, Thermal Characteristics Section, and Table 7 ............................................................................................... 11 Change to Digital Inputs Description, Table 8 ............................ 13 Added AD9680-1000 Section, Figure 10, and Figure 11; Renumbered Sequentially .............................................................. 14 Changes to Figure 6 to Figure 9 .................................................... 14 Added Figure 12 to Figure 14 ........................................................ 15 Changes to Figure 15 to Figure 17 ................................................ 15 Changes to Figure 18 to Figure 21 ................................................ 16 Changes to Figure 25 and Figure 29 ............................................. 17 Changes to Figure 30 ...................................................................... 18 Deleted Figure 35, Figure 36, and Figure 38................................ 19 Added AD9680-500 Section and Figure 31 to Figure 54 ............. 19 Changes to Analog Input Considerations Section and Differential Input Configurations Section ................................... 25 Added Input Buffer Control Registers (0x018, 0x019, 0x01A, 0x935, 0x934, 0x11A) Section, Figure 66, Figure 68, and Table 9; Renumbered Sequentially .............................................................. 26 Changes to Analog Input Buffer Controls and SFDR Optimization Section and Figure 67 ............................................ 26 Added Figure 69 to Figure 72 ........................................................ 27 Added Figure 73 to Figure 75 ........................................................ 28 Changes to Table 10 ........................................................................ 28 Added Input Clock Divider ½ Period Delay Adjust Section and Clock Fine Delay Adjust Section ................................................... 30 Changes to Figure 83 and Temperature Diode Section ............. 31 Added Signal Monitor Section and Figure 86 to Figure 89 ....... 33 Changes to Table 11 ........................................................................ 39 Changes to Table 12 to Table 14 .................................................... 40 Changes to Table 16 ........................................................................ 41 Deleted Figure 65 and Figure 66 ................................................... 45 Changes to Table 17 ........................................................................ 45 Changes to Table 19 to Table 20 .................................................... 46 Changes to Table 22 ........................................................................ 47 Changes to Table 23 ........................................................................ 49 Changes to JESD204B Link Establishment Section ................... 53 Added Figure 105 to Figure 110 .................................................... 56 Changes to Example 1: Full Bandwidth Mode Section .............. 60 Added Multichip Synchronization Section, Figure 115 to Figure 117, and Table 28................................................................. 62 Added Test Modes Section and Table 29 to Table 33 ................. 66 Changes to Reading the Memory Map Register Table Section .......70 Changes to Table 36 ........................................................................ 71 Changes to Power Supply Recommendations Section, Figure 118, and Exposed Pad Thermal Heat Slug Recommendations Section ............................................................ 83 Changes to Ordering Guide ........................................................... 84 5/14—Revision 0: Initial Version Rev. C | Page 3 of 97 Product Overview Design Resources Online Documentation AD9680 Discussion Sample & Buy Data Sheet GENERAL DESCRIPTION The AD9680 is a dual, 14-bit, 1.25 GSPS/1 GSPS/820 MSPS/ 500 MSPS analog-to-digital converter (ADC). The device has an on-chip buffer and sample-and-hold circuit designed for low power, small size, and ease of use. This device is designed for sampling wide bandwidth analog signals of up to 2 GHz. The AD9680 is optimized for wide input bandwidth, high sampling rate, excellent linearity, and low power in a small package. function in the communications receiver. The programmable threshold detector allows monitoring of the incoming signal power using the fast detect output bits of the ADC. If the input signal level exceeds the programmable threshold, the fast detect indicator goes high. Because this threshold indicator has low latency, the user can quickly turn down the system gain to avoid an overrange condition at the ADC input. The dual ADC cores feature a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC features wide bandwidth inputs supporting a variety of user-selectable input ranges. An integrated voltage reference eases design considerations. Users can configure the Subclass 1 JESD204B-based high speed serialized output in a variety of one-, two-, or four-lane configurations, depending on the DDC configuration and the acceptable lane rate of the receiving logic device. Multiple device synchronization is supported through the SYSREF± and SYNCINB± input pins. The analog input and clock signals are differential inputs. Each ADC data output is internally connected to two digital downconverters (DDCs). Each DDC consists of up to five cascaded signal processing stages: a 12-bit frequency translator (NCO), and four half-band decimation filters. The DDCs are bypassed by default. In addition to the DDC blocks, the AD9680 has several functions that simplify the automatic gain control (AGC) The AD9680 has flexible power-down options that allow significant power savings when desired. All of these features can be programmed using a 1.8 V to 3.3 V capable, 3-wire SPI. The AD9680 is available in a Pb-free, 64-lead LFCSP and is specified over the −40°C to +85°C industrial temperature range. This product is protected by a U.S. patent. Rev. C | Page 4 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 SPECIFICATIONS DC SPECIFICATIONS AVDD1 = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, AVDD1_SR = 1.25 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, specified maximum sampling rate for each speed grade, AIN = −1.0 dBFS, clock divider = 2, default SPI settings, TA = 25°C, unless otherwise noted. Table 1. Parameter RESOLUTION ACCURACY No Missing Codes Offset Error Offset Matching Gain Error Gain Matching Differential Nonlinearity (DNL) Integral Nonlinearity (INL) TEMPERATURE DRIFT Offset Error Gain Error INTERNAL VOLTAGE REFERENCE Voltage INPUT-REFERRED NOISE VREF = 1.0 V ANALOG INPUTS Differential Input Voltage Range (Programmable) Common-Mode Voltage (VCM) Differential Input Capacitance1 Analog Input Full Power Bandwidth POWER SUPPLY AVDD1 AVDD2 AVDD3 AVDD1_SR DVDD DRVDD SPIVDD IAVDD1 IAVDD2 IAVDD3 IAVDD1_SR IDVDD2 IDRVDD1 IDRVDD (L = 2 Mode) ISPIVDD Temp Full AD9680-500 Min Typ Max 14 AD9680-820 Min Typ Max 14 Min 14 Full Full Full Full Full Full Guaranteed −0.3 0 +0.3 0 0.3 −6 0 +6 1 5.1 −0.6 ±0.5 +0.7 Guaranteed −0.3 0 +0.3 0 0.23 −6 0 +6 1 5.5 −0.7 ±0.5 +0.8 Full −4.5 −3.3 ±2.5 +5.0 ±2.5 +4.3 AD9680-1000 Typ Max AD9680-1250 Min Typ Max 14 Unit Bits Guaranteed −0.31 0 +0.31 0 0.23 −6 0 +6 1 4.5 −0.7 ±0.5 +0.8 Guaranteed −0.31 0 +0.31 0 0.3 −6 0 +6 1 4.5 −0.8 ±0.5 +0.8 % FSR % FSR % FSR % FSR LSB −5.7 −6 LSB ±2.5 +6.9 ±3 +6 Full Full −3 ±25 −10 ±54 −12 ±13.8 −15 92 ppm/°C ppm/°C Full 1.0 1.0 1.0 1.0 V 25°C 2.06 2.46 2.63 3.45 LSB rms Full 1.46 2.06 2.06 1.46 1.70 1.94 1.46 1.70 1.94 1.46 1.58 1.94 V p-p 25°C 2.05 2.05 2.05 2.05 V 25°C 1.5 1.5 1.5 1.5 pF 25°C 2 2 2 2 GHz Full Full Full Full Full Full Full Full Full Full Full Full Full 25°C Full 1.22 2.44 3.2 1.22 1.22 1.22 1.7 1.25 2.50 3.3 1.25 1.25 1.25 1.8 435 395 87 15 145 190 140 5 1.28 2.56 3.4 1.28 1.28 1.28 3.4 467 463 101 22 152 237 6 1.22 2.44 3.2 1.22 1.22 1.22 1.7 1.25 2.50 3.3 1.25 1.25 1.25 1.8 605 490 125 15 205 200 N/A3 5 1.28 2.56 3.4 1.28 1.28 1.28 3.4 660 545 140 18 246 240 6 Rev. C | Page 5 of 97 1.22 2.44 3.2 1.22 1.22 1.22 1.7 1.25 2.50 3.3 1.25 1.25 1.25 1.8 685 595 125 16 208 200 N/A3 5 1.28 2.56 3.4 1.28 1.28 1.28 3.4 720 680 142 18 269 225 6 1.22 2.44 3.2 1.22 1.22 1.22 1.7 1.25 2.50 3.3 1.25 1.25 1.25 1.8 785 675 125 17 250 220 N/A3 5 1.28 2.56 3.4 1.28 1.28 1.28 3.4 880 780 142 20 325 300 6 V V V V V V V mA mA mA mA mA mA mA mA Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Parameter POWER CONSUMPTION Total Power Dissipation (Including Output Drivers)2 Total Power Dissipation (L = 2 Mode) Power-Down Dissipation Standby4 Data Sheet Temp AD9680-500 Min Typ Max AD9680-820 Min Typ Max AD9680-1000 Min Typ Max AD9680-1250 Min Typ Max Unit Full 2.2 2.9 3.3 3.7 W 25°C 2.1 N/A3 N/A3 N/A3 W Full Full 700 1.2 820 1.3 835 1.4 1030 1.66 mW W All lanes running. Power dissipation on DRVDD changes with lane rate and number of lanes used. Default mode. No DDCs used. L = 4, M = 2, F = 1. 3 N/A means not applicable. At the maximum sample rate, it is not applicable to use L = 2 mode on the JESD204B output interface because this exceeds the maximum lane rate of 12.5 Gbps. L = 2 mode is supported when the equation ((M × N΄ × (10/8) × fOUT)/L) results in a line rate that is ≤12.5 Gbps. fOUT is the output sample rate and is denoted by fS/DCM, where DCM is the decimation ratio. 4 Can be controlled by the SPI. 1 2 AC SPECIFICATIONS AVDD1 = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, AVDD1_SR = 1.25 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, specified maximum sampling rate for each speed grade, AIN = −1.0 dBFS, clock divider = 2, default SPI settings, TA = 25°C, unless otherwise noted. Table 2. Parameter1 ANALOG INPUT FULL SCALE NOISE DENSITY2 SIGNAL-TO-NOISE RATIO (SNR)3 fIN = 10 MHz fIN = 170 MHz fIN = 340 MHz fIN = 450 MHz fIN = 765 MHz fIN = 985 MHz fIN = 1950 MHz SNR AND DISTORTION RATIO (SINAD)3 fIN = 10 MHz fIN = 170 MHz fIN = 340 MHz fIN = 450 MHz fIN = 765 MHz fIN = 985 MHz fIN = 1950 MHz EFFECTIVE NUMBER OF BITS (ENOB) fIN = 10 MHz fIN = 170 MHz fIN = 340 MHz fIN = 450 MHz fIN = 765 MHz fIN = 985 MHz fIN = 1950 MHz Temp Full Full 25°C Full 25°C 25°C 25°C 25°C 25°C 25°C Full 25°C 25°C 25°C 25°C 25°C 25°C Full 25°C 25°C 25°C 25°C 25°C AD9680-500 Min Typ Max 2.06 −153 67.8 67.6 10.9 69.2 69.0 68.6 68.0 64.4 63.8 60.5 69.0 68.8 68.4 67.9 64.2 63.6 60.3 11.2 11.1 11.1 11.0 10.4 10.3 9.7 AD9680-820 Min Typ Max 1.7 −153 65.6 65.2 10.5 67.2 67.0 66.5 65.1 64.0 63.4 59.7 67.1 66.8 66.3 64.7 63.5 62.7 58.7 10.9 10.8 10.7 10.5 10.3 10.1 9.5 Rev. C | Page 6 of 97 AD9680-1000 Min Typ Max 1.7 −154 65.1 65.0 10.5 67.2 66.6 65.3 64.0 61.5 60.5 57.0 67.1 66.4 65.2 63.8 62.1 61.1 56.0 10.8 10.7 10.5 10.3 10.0 9.8 9.0 AD9680-1250 Min Typ Max 1.58 −151.5 61.5 61.4 9.9 Unit V p-p dBFS/Hz 63.6 63.2 62.8 62.2 61.1 59.2 55.5 dBFS dBFS dBFS dBFS dBFS dBFS dBFS 63.5 62.8 62.6 61.8 60.8 58.2 51.5 dBFS dBFS dBFS dBFS dBFS dBFS dBFS 10.3 10.1 10.1 10.0 9.8 9.4 8.3 Bits Bits Bits Bits Bits Bits Bits Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet Parameter1 SPURIOUS-FREE DYNAMIC RANGE (SFDR)3 fIN = 10 MHz fIN = 170 MHz fIN = 340 MHz fIN = 450 MHz fIN = 765 MHz fIN = 985 MHz fIN = 1950 MHz WORST HARMONIC, SECOND OR THIRD3 fIN = 10 MHz fIN = 170 MHz fIN = 340 MHz fIN = 450 MHz fIN = 765 MHz fIN = 985 MHz fIN = 1950 MHz WORST OTHER, EXCLUDING SECOND OR THIRD HARMONIC3 fIN = 10 MHz fIN = 170 MHz fIN = 340 MHz fIN = 450 MHz fIN = 765 MHz fIN = 985 MHz fIN = 1950 MHz TWO-TONE INTERMODULATION DISTORTION (IMD), AIN1 AND AIN2 = −7 dBFS fIN1 = 185 MHz, fIN2 = 188 MHz fIN1 = 338 MHz, fIN2 = 341 MHz CROSSTALK5 FULL POWER BANDWIDTH6 AD9680 Temp 25°C Full 25°C 25°C 25°C 25°C 25°C AD9680-500 Min Typ Max 80 83 88 83 81 80 75 70 AD9680-820 Min Typ Max 75 91 83 81 78 78 74 70 75 88 85 85 82 82 80 68 74 84 77 78 76 77 71 61 dBFS dBFS dBFS dBFS dBFS dBFS dBFS 25°C Full 25°C 25°C 25°C 25°C 25°C −95 −95 −93 −93 −88 −89 −84 25°C −88 −90 −87 −82 dBFS 25°C −88 −87 −88 −784 dBFS 25°C 25°C 95 2 95 2 95 2 95 2 dB GHz −82 −97 −93 −91 −90 −83 −84 −74 −80 −95 −94 −88 −86 −81 −82 −75 −75 −81 −84 −77 −78 −76 −77 −71 −61 Unit −83 −88 −83 −81 −80 −75 −70 −75 −88 −85 −85 −82 −82 −80 −68 AD9680-1250 Min Typ Max 25°C Full 25°C 25°C 25°C 25°C 25°C −80 −91 −83 −81 −78 −78 −74 −70 AD9680-1000 Min Typ Max −87 −79 −81 −79 −79 −77 −69 −74 −74 See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for definitions and for details on how these tests were completed. Noise density is measured at a low analog input frequency (30 MHz). 3 See Table 10 for the recommended settings for full-scale voltage and buffer current settings. 4 Measurement taken with 449 MHz and 452 MHz inputs for two-tone. 5 Crosstalk is measured at 170 MHz with a −1.0 dBFS analog input on one channel and no input on the adjacent channel. 6 Measured with the circuit shown in Figure 115. 1 2 Rev. C | Page 7 of 97 dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS dBFS Product Overview Design Resources Online Documentation Discussion AD9680 Sample & Buy Data Sheet DIGITAL SPECIFICATIONS AVDD1 = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, AVDD1_SR = 1.25 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, specified maximum sampling rate for each speed grade, AIN = −1.0 dBFS, clock divider = 2, default SPI settings, TA = 25°C, unless otherwise noted. Table 3. Parameter CLOCK INPUTS (CLK+, CLK−) Logic Compliance Differential Input Voltage Input Common-Mode Voltage Input Resistance (Differential) Input Capacitance SYSREF INPUTS (SYSREF+, SYSREF−) Logic Compliance Differential Input Voltage Input Common-Mode Voltage Input Resistance (Differential) Input Capacitance (Differential) LOGIC INPUTS (SDI, SCLK, CSB, PDWN/STBY) Logic Compliance Logic 1 Voltage Logic 0 Voltage Input Resistance LOGIC OUTPUT (SDIO) Logic Compliance Logic 1 Voltage (IOH = 800 µA) Logic 0 Voltage (IOL = 50 µA) SYNCIN INPUT (SYNCINB+/SYNCINB−) Logic Compliance Differential Input Voltage Input Common-Mode Voltage Input Resistance (Differential) Input Capacitance LOGIC OUTPUTS (FD_A, FD_B) Logic Compliance Logic 1 Voltage Logic 0 Voltage Input Resistance DIGITAL OUTPUTS (SERDOUTx±, x = 0 TO 3) Logic Compliance Differential Output Voltage Output Common-Mode Voltage (VCM) AC-Coupled Short-Circuit Current (IDSHORT) Differential Return Loss (RLDIFF)1 Common-Mode Return Loss (RLCM)1 Differential Termination Impedance 1 Temperature Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Min 600 Typ LVDS/LVPECL 1200 0.85 35 Max Unit 1800 mV p-p V kΩ pF 2.5 400 0.6 LVDS/LVPECL 1200 0.85 35 1800 2.0 2.5 mV p-p V kΩ pF CMOS 0.8 × SPIVDD 0 0.5 30 V V kΩ CMOS 0.8 × SPIVDD 0 400 0.6 0.5 LVDS/LVPECL/CMOS 1200 0.85 35 1800 2.0 2.5 V V mV p-p V kΩ pF CMOS 0.8 × SPIVDD 0 0.5 V V kΩ 30 Full Full 360 770 mV p-p 25°C 25°C 25°C 25°C Full 0 −100 8 6 80 1.8 +100 V mA dB dB Ω Differential and common-mode return loss are measured from 100 MHz to 0.75 × baud rate. Rev. C | Page 8 of 97 CML 100 120 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 SWITCHING SPECIFICATIONS AVDD1 = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, AVDD1_SR = 1.25 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, specified maximum sampling rate for each speed grade, AIN = −1.0 dBFS, default SPI settings, TA = 25°C, unless otherwise noted. Table 4. Parameter CLOCK Clock Rate (at CLK+/CLK− Pins) Maximum Sample Rate1 Minimum Sample Rate2 Clock Pulse Width High Clock Pulse Width Low OUTPUT PARAMETERS Unit Interval (UI)3 Rise Time (tR) (20% to 80% into 100 Ω Load) Fall Time (tF) (20% to 80% into 100 Ω Load) PLL Lock Time Data Rate per Channel (NRZ)4 LATENCY5 Pipeline Latency Fast Detect Latency Wake-Up Time6 Standby Power-Down APERTURE Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) Out-of-Range Recovery Time Temp AD9680-500 Min Typ Max Min Full 0.3 0.3 Full Full Full Full 500 300 1000 1000 Full 25°C 80 24 200 32 80 24 121.95 32 80 24 100 32 80 24 80 32 ps ps 25°C 24 32 24 32 24 32 24 32 ps 25°C 25°C 3.125 2 5 3.125 2 8.2 3.125 2 10 3.1215 2 12.5 Full 4 AD9680-820 Typ Max 4 820 300 609.7 609.7 12.5 55 Full AD9680-1000 Min Typ Max AD9680-1250 Min Typ Max Unit 0.3 0.3 GHz 4 1000 300 500 500 12.5 55 28 1250 300 400 400 12.5 55 28 1 4 MSPS MSPS ps ps 12.5 55 28 1 Full Full 530 55 530 55 530 55 530 55 ps fS rms Full 1 1 1 1 Clock cycles 4 The maximum sample rate is the clock rate after the divider. The minimum sample rate operates at 300 MSPS with L = 2 or L = 1. 3 Baud rate = 1/UI. A subset of this range can be supported. 4 Default L = 4. This number can be changed based on the sample rate and decimation ratio. 5 No DDCs used. L = 4, M = 2, F = 1. 6 Wake-up time is defined as the time required to return to normal operation from power-down mode. 1 2 Rev. C | Page 9 of 97 1 Clock cycles Clock cycles 25°C 25°C 4 1 28 ms Gbps 4 4 ms ms Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet TIMING SPECIFICATIONS Table 5. Parameter CLK+ to SYSREF+ TIMING REQUIREMENTS tSU_SR tH_SR SPI TIMING REQUIREMENTS tDS tDH tCLK tS tH tHIGH tLOW tACCESS Test Conditions/Comments See Figure 3 Device clock to SYSREF+ setup time Device clock to SYSREF+ hold time See Figure 4 Setup time between the data and the rising edge of SCLK Hold time between the data and the rising edge of SCLK Period of the SCLK Setup time between CSB and SCLK Hold time between CSB and SCLK Minimum period that SCLK must be in a logic high state Minimum period that SCLK must be in a logic low state Maximum time delay between falling edge of SCLK and output data valid for a read operation Time required for the SDIO pin to switch from an output to an input relative to the SCLK rising edge (not shown in Figure 4) tDIS_SDIO Min Typ Max Unit 117 −96 ps ps 6 ns ns ns ns ns ns ns ns 2 2 40 2 2 10 10 10 10 ns Timing Diagrams APERTURE DELAY ANALOG INPUT SIGNAL SAMPLE N N – 54 N+1 N – 55 N – 53 N – 52 N–1 N – 51 CLK– CLK+ CLK– CLK+ SERDOUT0– A B C D E F G H I J A B C D E F G H I J A B C D E F G H I J CONVERTER0 MSB A B C D E F G H I J A B C D E F G H I J A B C D E F G H I J CONVERTER0 LSB A B C D E F G H I J A B C D E F G H I J A B C D E F G H I J CONVERTER1 MSB A B C D E F G H I J A B C D E F G H I J A B C D E F G H I J CONVERTER1 LSB SERDOUT0+ SERDOUT1– SERDOUT1+ SERDOUT2– SERDOUT2+ SERDOUT3– SAMPLE N – 55 ENCODED INTO 1 8-BIT/10-BIT SYMBOL SAMPLE N – 54 ENCODED INTO 1 8-BIT/10-BIT SYMBOL SAMPLE N – 53 ENCODED INTO 1 8-BIT/10-BIT SYMBOL Figure 2. Data Output Timing (Full Bandwidth Mode; L = 4; M = 2; F = 1) Rev. C | Page 10 of 97 11752-002 SERDOUT3+ Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 CLK– CLK+ tH_SR tSU_SR 11752-003 SYSREF– SYSREF+ Figure 3. SYSREF± Setup and Hold Timing tHIGH tDS tS tCLK tDH tACCESS tH tLOW CSB SDIO DON’T CARE DON’T CARE R/W A14 A13 A12 A11 A10 A9 A8 A7 D7 Figure 4. Serial Port Interface Timing Diagram Rev. C | Page 11 of 97 D6 D3 D2 D1 D0 DON’T CARE 11752-004 SCLK DON’T CARE Product Overview Design Resources Online Documentation Sample & Buy Discussion AD9680 Data Sheet ABSOLUTE MAXIMUM RATINGS THERMAL CHARACTERISTICS Table 6. Parameter Electrical AVDD1 to AGND AVDD1_SR to AGND AVDD2 to AGND AVDD3 to AGND DVDD to DGND DRVDD to DRGND SPIVDD to AGND AGND to DRGND VIN±x to AGND SCLK, SDIO, CSB to AGND PDWN/STBY to AGND Operating Temperature Range Junction Temperature Range Storage Temperature Range (Ambient) Rating 1.32 V 1.32 V 2.75 V 3.63 V 1.32 V 1.32 V 3.63 V −0.3 V to +0.3 V 3.2 V −0.3 V to SPIVDD + 0.3 V −0.3 V to SPIVDD + 0.3 V −40°C to +85°C −40°C to +115°C −65°C to +150°C Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. Typical θJA, θJB, and θJC are specified vs. the number of printed circuit board (PCB) layers in different airflow velocities (in m/sec). Airflow increases heat dissipation effectively reducing θJA and θJB. In addition, metal in direct contact with the package leads and exposed pad from metal traces, through holes, ground, and power planes, reduces θJA. Thermal performance for actual applications requires careful inspection of the conditions in an application. The use of appropriate thermal management techniques is recommended to ensure that the maximum junction temperature does not exceed the limits shown in Table 6. Table 7. Thermal Resistance Values PCB Type JEDEC 2s2p Board Airflow Velocity (m/sec) 0.0 1.0 2.5 θJA 17.81, 2 15.61, 2 15.01, 2 ΨJB 6.31, 3 5.91, 3 5.71, 3 θJC_TOP 4.71, 4 N/A5 N/A5 θJC_BOT 1.21, 4 Per JEDEC 51-7, plus JEDEC 51-5 2s2p test board. Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air). 3 Per JEDEC JESD51-8 (still air). 4 Per MIL-STD 883, Method 1012.1. 5 N/A means not applicable. 1 2 ESD CAUTION Rev. C | Page 12 of 97 Unit °C/W °C/W °C/W Design Resources Online Documentation Product Overview Discussion Data Sheet Sample & Buy AD9680 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AVDD1 AVDD2 AVDD2 AVDD1 AGND SYSREF– SYSREF+ AVDD1_SR AGND AVDD1 CLK– CLK+ AVDD1 AVDD2 AVDD2 AVDD1 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 AD9680 TOP VIEW (Not to Scale) AVDD1 AVDD1 AVDD2 AVDD3 VIN–B VIN+B AVDD3 AVDD2 AVDD2 AVDD2 SPIVDD CSB SCLK SDIO DVDD DGND NOTES 1. EXPOSED PAD. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE PROVIDES THE GROUND REFENCE FOR AVDDx. THIS EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION. 11752-005 FD_A DRGND DRVDD SYNCINB– SYNCINB+ SERDOUT0– SERDOUT0+ SERDOUT1– SERDOUT1+ SERDOUT2– SERDOUT2+ SERDOUT3– SERDOUT3+ DRVDD DRGND FD_B 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 AVDD1 AVDD1 AVDD2 AVDD3 VIN–A VIN+A AVDD3 AVDD2 AVDD2 AVDD2 AVDD2 V_1P0 SPIVDD PDWN/STBY DVDD DGND Figure 5. Pin Configuration (Top View) Table 8. Pin Function Descriptions Pin No. Power Supplies 0 Mnemonic Type Description EPAD Ground 1, 2, 47, 48, 49, 52, 55, 61, 64 3, 8, 9, 10, 11, 39, 40, 41, 46, 50, 51, 62, 63 4, 7, 42, 45 13, 38 15, 34 16, 33 18, 31 19, 30 56, 60 57 Analog 5, 6 12 AVDD1 AVDD2 Supply Supply Exposed Pad. The exposed thermal pad on the bottom of the package provides the ground reference for AVDDx. This exposed pad must be connected to ground for proper operation. Analog Power Supply (1.25 V Nominal). Analog Power Supply (2.5 V Nominal). AVDD3 SPIVDD DVDD DGND DRGND DRVDD AGND1 AVDD1_SR1 Supply Supply Supply Ground Ground Supply Ground Supply Analog Power Supply (3.3 V Nominal). Digital Power Supply for SPI (1.8 V to 3.3 V). Digital Power Supply (1.25 V Nominal). Ground Reference for DVDD. Ground Reference for DRVDD. Digital Driver Power Supply (1.25 V Nominal). Ground Reference for SYSREF±. Analog Power Supply for SYSREF± (1.25 V Nominal). VIN−A, VIN+A V_1P0 Input Input/DNC VIN−B, VIN+B CLK+, CLK− Input Input ADC A Analog Input Complement/True. 1.0 V Reference Voltage Input/Do Not Connect. This pin is configurable through the SPI as a no connect or an input. Do not connect this pin if using the internal reference. Requires a 1.0 V reference voltage input if using an external voltage reference source. ADC B Analog Input Complement/True. Clock Input True/Complement. 44, 43 53, 54 Rev. C | Page 13 of 97 Design Resources Online Documentation Product Overview Discussion AD9680 Pin No. CMOS Outputs 17, 32 Digital Inputs 20, 21 58, 59 Data Outputs 22, 23 24, 25 26, 27 28, 29 Device Under Test (DUT) Controls 14 35 36 37 1 Sample & Buy Data Sheet Mnemonic Type Description FD_A, FD_B Output Fast Detect Outputs for Channel A and Channel B. SYNCINB−, SYNCINB+ SYSREF+, SYSREF− Input Input Active Low JESD204B LVDS Sync Input True/Complement. Active High JESD204B LVDS System Reference Input True/Complement. SERDOUT0−, SERDOUT0+ SERDOUT1−, SERDOUT1+ SERDOUT2−, SERDOUT2+ SERDOUT3−, SERDOUT3+ Output Output Output Output Lane 0 Output Data Complement/True. Lane 1 Output Data Complement/True. Lane 2 Output Data Complement/True. Lane 3 Output Data Complement/True. PDWN/STBY Input SDIO SCLK CSB Input/Output Input Input Power-Down Input (Active High). The operation of this pin depends on the SPI mode and can be configured as powerdown or standby. Requires an external 10 kΩ pull-down resistor. SPI Serial Data Input/Output. SPI Serial Clock. SPI Chip Select (Active Low). To ensure proper ADC operation, connect AVDD1_SR and AGND separately from the AVDD1 and EPAD connection. For more information, see the Applications Information section. Rev. C | Page 14 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 TYPICAL PERFORMANCE CHARACTERISTICS AD9680-1250 AVDD1 = 1.25 V, AVDD1_SR = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, 1.58 V p-p full-scale differential input, AIN = −1.0 dBFS, default SPI settings, clock divider = 2, TA = 25°C, 128k FFT sample, unless otherwise noted. See Table 10 for recommended settings. AIN = –1dBFS SNR = 64dBFS ENOB = 10.3 BITS SFDR = 82dBFS BUFFER CURRENT = 3.5× –10 –30 AMPLITUDE (dBFS) –50 –70 –90 –110 –50 –70 –90 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) –130 11752-606 –130 0 AIN = –1dBFS SNR = 60.9dBFS ENOB = 9.8 BITS SFDR = 74dBFS BUFFER CURRENT = 5.5× –10 –30 AMPLITUDE (dBFS) AMPLITUDE (dBFS) Figure 9. Single-Tone FFT with fIN = 450.3 MHz AIN = –1dBFS SNR = 63.4dBFS ENOB = 10.2 BITS SFDR = 79dBFS BUFFER CURRENT = 3.5× –30 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) Figure 6. Single-Tone FFT with fIN = 10.3 MHz –10 78.125 11752-609 –110 –50 –70 –90 –110 –50 –70 –90 –110 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) –130 11752-607 –130 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) Figure 7. Single-Tone FFT with fIN = 170.3 MHz 11752-610 AMPLITUDE (dBFS) –30 AIN = –1dBFS SNR = 62.5dBFS ENOB = 9.9 BITS SFDR = 70dBFS BUFFER CURRENT = 3.5× –10 Figure 10. Single-Tone FFT with fIN = 765.3 MHz 0 AIN = –1dBFS SNR = 62.8dBFS ENOB = 10.1 BITS SFDR = 76dBFS BUFFER CURRENT = 3.5× –10 AMPLITUDE (dBFS) –20 –50 –70 –90 –40 –60 –80 –130 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) Figure 8. Single-Tone FFT with fIN = 340.3 MHz –120 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) Figure 11. Single-Tone FFT with fIN = 985.3 MHz Rev. C | Page 15 of 97 11752-611 –100 –110 11752-608 AMPLITUDE (dBFS) –30 AIN = –1dBFS SNR = 59.7dBFS ENOB = 9.6 BITS SFDR = 74dBFS BUFFER CURRENT = 5.5× Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 85 0 AIN = –1dBFS SNR = 58.5dBFS ENOB = 9.3 BITS SFDR = 68dBFS BUFFER CURRENT = 5.5× 80 –40 SNR/SFDR (dBFS) AMPLITUDE (dBFS) –20 –60 –80 SFDR 75 70 65 –100 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) 60 11752-612 –120 Figure 12. Single-Tone FFT with fIN = 1205.3 MHz 1000 1020 1040 1060 1080 1100 1120 1140 1160 1180 1200 1220 1240 1260 SAMPLE RATE (MHz) Figure 15. SNR/SFDR vs. fS, fIN = 170.3 MHz; Buffer Control 1 (0x018) = 3.5× 85 0 AIN = –1dBFS SNR = 56.6dBFS ENOB = 9.0 BITS SFDR = 67dBFS BUFFER CURRENT = 7.5× 3.5× SNR (dBFS) 3.5× SFDR (dBFS) 4.5× SNR (dBFS) 4.5× SFDR (dBFS) 80 SNR/SFDR (dBFS) –40 –60 –80 75 70 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) 60 10.3 11752-613 –120 147.3 212.3 290.3 355.3 433.3 511.3 589.3 667.3 INPUT FREQUENCY (MHz) Figure 13. Single-Tone FFT with fIN = 1602.3 MHz 11752-616 65 –100 Figure 16. SNR/SFDR vs. fIN; fIN < 700 MHz; Buffer Control 1 (0x018) = 3.5× and 4.5× 80 0 AIN = –1dBFS SNR = 55.4dBFS ENOB = 8.8 BITS SFDR = 63dBFS BUFFER CURRENT = 8.5× –20 SNR 6.5× SFDR 6.5× 75 SNR/SFDR (dBFS) –40 –60 –80 70 65 60 –120 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) 11752-614 –100 55 628.3 706.6 784.3 862.3 940.3 1018.3 1096.3 1174.3 1252.3 INPUT FREQUENCY (MHz) Figure 17. SNR/SFDR vs. fIN; 650 MHz < fIN < 1.3 GHz; Buffer Control 1 (0x018) = 6.5× Figure 14. Single-Tone FFT with fIN = 1954.3 MHz Rev. C | Page 16 of 97 11752-617 AMPLITUDE (dBFS) –20 AMPLITUDE (dBFS) 11752-615 SNR Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 0 80 SNR 8.5× SFDR 8.5× –20 SFDR/IMD3 (dBc AND dBFS) 70 65 60 –60 –80 1356.3 1460.3 1564.3 1668.3 177.23 1876.3 1980.3 INPUT FREQUENCY (MHz) –120 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 –6 11752-618 50 1252.3 0 INPUT AMPLITUDE (dBFS) Figure 18. SNR/SFDR vs. fIN; 1.3 GHz < fIN < 2GHz; Buffer Control 1 (0x018) = 8.5× 11752-622 –100 55 Figure 21. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184 MHz and fIN2 = 187 MHz 0 0 AIN1 AND AIN2 = –7dBFS SFDR = 82dBFS IMD2 = 84dBFS IMD3 = 82dBFS BUFFER CURRENT = 3.5× IMD3 (dBc) IMD3 (dBFS) SFDR (dBFS) SFDR (dBc) –20 SFDR/IMD3 (dBc AND dBFS) –20 –40 –60 –80 –100 –40 –60 –80 –100 –120 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) –140 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 –6 11752-095 –120 0 INPUT AMPLITUDE (dBFS) Figure 19. Two-Tone FFT; fIN1 = 184 MHz, fIN2 = 187 MHz 11752-623 AMPLITUDE (dBFS) –40 Figure 22. Two-Tone IMD3/SFDR vs. Input Amplitude (AIN) with fIN1 = 449 MHz and fIN2 = 452 MHz 0 120 AIN1 AND AIN2 = –7dBFS SFDR = 78dBFS IMD2 = 78dBFS IMD3 = 78dBFS BUFFER CURRENT = 5.5× –20 100 80 SNR/SFDR (dB) –40 –60 60 40 20 –80 0 –100 SNR (dBFS) SNR (dBc) SFDR (dBc) SFDR (dBFS) –120 0 78.125 156.250 234.375 312.500 390.625 468.750 546.875 625.000 FREQUENCY (MHz) 11752-096 –20 Figure 20. Two-Tone FFT; fIN1 = 449 MHz, fIN2 = 452 MHz –40 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 –6 0 INPUT AMPLITUDE (dBFS) Figure 23. SNR/SFDR vs. Analog Input Level, fIN = 170.3 MHz Rev. C | Page 17 of 97 11752-624 SNR/SFDR (dBFS) 75 AMPLITUDE (dBFS) IMD3 (dBc) IMD3 (dBFS) SFDR (dBFS) SFDR (dBc) Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 1200000 85 3.45 LSB rms SFDR 1000000 NUMBER OF HITS SNR/SFDR (dBFS) 80 75 70 65 800000 600000 400000 SNR 12 22 32 42 52 62 72 82 92 102 112 TEMPERATURE (°C) 0 11752-628 2 11752-625 55 –48 –38 –28 –18 –8 N – 10 N–9 N–8 N–7 N–6 N–5 N–4 N–3 N–2 N–1 N N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 N+9 N + 10 200000 60 CODE Figure 24. SNR/SFDR vs. Temperature, fIN = 170.3 MHz Figure 27. Input-Referred Noise Histogram 4 4.00 3 3.95 3.90 2 3.85 POWER (W) INL (LSB) 1 0 –1 3.80 3.75 3.70 –2 3.65 –3 0 2000 4000 6000 8000 10000 12000 14000 16000 OUTPUT CODE 3.55 –48 –38 –28 –18 –8 11752-626 –4 Figure 25. INL, fIN = 10.3 MHz 12 22 32 42 52 62 72 82 Figure 28. Power Dissipation vs. Temperature 0.4 4.0 0.3 3.9 POWER DISSIPATION (W) 0.2 0.1 0 –0.1 –0.2 3.8 3.7 3.6 3.5 –0.4 0 2000 4000 6000 8000 10000 12000 OUTPUT CODE 14000 16000 Figure 26. DNL, fIN = 15 MHz 3.3 1000 1020 1040 1060 1080 1100 1120 1140 1160 1180 1200 1220 1240 1260 SAMPLE RATE (MHz) Figure 29. Power Dissipation vs. fS Rev. C | Page 18 of 97 11752-630 3.4 –0.3 11752-627 DNL (LSB) 2 TEMPERATURE (°C) 11752-629 3.60 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 AD9680-1000 AVDD1 = 1.25 V, AVDD1_SR = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, 1.7 V p-p full-scale differential input, AIN = −1.0 dBFS, default SPI settings, clock divider = 2, TA = 25°C, 128k FFT sample, unless otherwise noted. See Table 10 for recommended settings. AIN = –1dBFS SNR = 67.2dBFS ENOB = 10.8 BITS SFDR = 88dBFS BUFFER CONTROL 1 = 1.5× –10 –30 AMPLITUDE (dBFS) –50 –70 –90 –50 –70 –90 0 100 200 300 400 500 FREQUENCY (MHz) –130 11752-100 –130 0 500 AIN = –1dBFS SNR = 61.5dBFS ENOB = 10.1 BITS SFDR = 82dBFS BUFFER CONTROL 1 = 6.0× –20 AMPLITUDE (dBFS) –50 –70 –90 –40 –60 –80 –100 0 100 200 300 400 500 FREQUENCY (MHz) –120 11752-101 –130 0 100 200 0 AIN = –1dBFS SNR = 65.3dBFS ENOB = 10.5 BITS SFDR = 85dBFS BUFFER CONTROL 1 = 3.0× 500 AIN = –1dBFS SNR = 60.5dBFS ENOB = 9.9 BITS SFDR = 80dBFS BUFFER CONTROL 1 = 6.0× –20 AMPLITUDE (dBFS) –30 400 Figure 34. Single-Tone FFT with fIN = 765.3 MHz Figure 31. Single-Tone FFT with fIN = 170.3 MHz –10 300 FREQUENCY (MHz) 11752-104 AMPLITUDE (dBFS) 400 0 –110 –50 –70 –90 –40 –60 –80 –100 –110 –120 –130 0 100 200 300 400 FREQUENCY (MHz) 500 11752-102 AMPLITUDE (dBFS) 300 Figure 33. Single-Tone FFT with fIN = 450.3 MHz AIN = –1dBFS SNR = 66.6dBFS ENOB = 10.7 BITS SFDR = 85dBFS BUFFER CONTROL 1 = 3.0× –30 200 FREQUENCY (MHz) Figure 30. Single-Tone FFT with fIN = 10.3 MHz –10 100 11752-103 –110 –110 0 100 200 300 400 FREQUENCY (MHz) Figure 35. Single-Tone FFT with fIN = 985.3 MHz Figure 32. Single-Tone FFT with fIN = 340.3 MHz Rev. C | Page 19 of 97 500 11752-105 AMPLITUDE (dBFS) –30 AIN = –1dBFS SNR = 64.0dBFS ENOB = 10.3 BITS SFDR = 82dBFS BUFFER CONTROL 1 = 3.0× –10 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 0 90 AIN = –1dBFS SNR = 59.8BFS ENOB = 9.6 BITS SFDR = 79dBFS BUFFER CONTROL 1 = 8.0× –20 85 SFDR (dBFS) –40 SNR/SFDR (dBFS) AMPLITUDE (dBFS) Data Sheet –60 –80 80 75 70 SNR (dBFS) –100 0 100 200 300 400 500 FREQUENCY (MHz) 60 700 750 800 850 900 950 1000 1050 11752-201 –120 11752-107 65 1100 SAMPLE RATE (MHz) Figure 39. SNR/SFDR vs. fS, fIN = 170.3 MHz; Buffer Control 1 (0x018) = 3.0× Figure 36. Single-Tone FFT with fIN = 1293.3 MHz 90 0 85 80 SNR/SFDR (dBFS) AMPLITUDE (dBFS) AIN = –1dBFS SNR = 57.7dBFS ENOB = 9.2 BITS –20 SFDR = 70dBFS BUFFER CONTROL 1 = 8.0× –40 –60 –80 75 70 65 55 1.5× SFDR (dBFS) 1.5× SNR (dBFS) 3.0× SFDR (dBFS) 3.0× SNR (dBFS) 0 100 200 300 400 500 FREQUENCY (MHz) 11752-108 –120 50 10.3 63.3 ANALOG INPUT FREQUENCY (MHz) Figure 40. SNR/SFDR vs. fIN; fIN < 500 MHz; Buffer Control 1 (0x018) = 1.5× and 3.0× Figure 37. Single-Tone FFT with fIN = 1725.3 MHz 100 0 AIN = –1dBFS SNR = 57.0dBFS ENOB = 9.1 BITS SFDR = 69dBFS BUFFER CURRENT = 6.0× 90 SNR/SFDR (dBFS) –20 –40 –60 –80 80 70 60 –120 0 100 200 300 FREQUENCY (MHz) 400 500 50 476.8 4.0× SFDR 4.0× SNRFS 6.0× SFDR 6.0× SNRFS 554.4 593.2 670.8 748.4 826.0 903.6 981.2 ANALOG INPUT FREQUENCY (MHz) Figure 41. SNR/SFDR vs. fIN; 500 MHz < fIN < 1 GHz; Buffer Control 1 (0x018) = 4.0× and 6.0× Figure 38. Single-Tone FFT with fIN = 1950.3 MHz Rev. C | Page 20 of 97 11752-218 –100 11752-506 AMPLITUDE (dBFS) 100.3 170.3 225.3 302.3 341.3 403.3 453.3 502.3 11752-216 60 –100 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 100 0 –20 AMPLITUDE (dBFS) 90 80 SFDR 70 –40 –60 –80 SNR 60 50 978.5 1142.4 1065.0 1220.0 1297.3 1452.2 1374.8 –120 ANALOG INPUT FREQUENCY (MHz) 0 100 200 300 Figure 42. SNR/SFDR vs. fIN; 1 GHz < fIN < 1.5 GHz; Buffer Control 1 (0x018) = 6.0× 500 Figure 45. Two-Tone FFT; fIN1 = 338 MHz, fIN2 = 341 MHz 100 20 SFDR (dBc) SFDR (dBFS) IMD3 (dBc) IMD3 (dBFS) 0 SFDR/IMD3 (dBc AND dBFS) 90 80 SFDR 70 60 SNR 1607.4 1701.6 –40 –60 –80 –100 –120 11752-220 50 1513.3 –20 1889.7 1795.6 ANALOG INPUT FREQUENCY (MHz) –140 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 –6 INPUT AMPLITUDE (dBFS) Figure 46. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184 MHz and fIN2 = 187 MHz Figure 43. SNR/SFDR vs. fIN; 1.5 GHz < fIN < 2 GHz; Buffer Control 1 (0x018) = 7.5× 20 0 AIN1 AND AIN2 = –7dBFS SFDR = 87dBFS IMD2 = 93dBFS IMD3 = 87dBFS BUFFER CONTROL 1 = 3.0× SFDR (dBc) SFDR (dBFS) IMD3 (dBc) IMD3 (dBFS) 0 SNR/SFDR (dBc AND dBFS) –20 –40 –60 –80 –20 –40 –60 –80 –100 –100 –120 0 100 200 300 400 FREQUENCY (MHz) 500 –140 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 –6 INPUT AMPLITUDE (dBFS) Figure 47. Two-Tone IMD3/SFDR vs. Input Amplitude (AIN) with fIN1 = 338 MHz and fIN2 = 341 MHz Figure 44. Two-Tone FFT; fIN1 = 184 MHz, fIN2 = 187 MHz Rev. C | Page 21 of 97 11752-208 –120 11752-205 AMPLITUDE (dBFS) 11752-207 SNR/SFDR (dBFS) 400 FREQUENCY (MHz) 11752-206 –100 11752-219 SNR/SFDR (dBFS) AIN1 AND AIN2 = –7dBFS SFDR = 88dBFS IMD2 = 93dBFS IMD3 = 88dBFS BUFFER CONTROL 1 = 4.5× Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 3 110 100 90 2 80 1 INL (LSB) SNR/SFDR (dB) 70 60 50 40 30 0 –1 20 10 –20 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 –6 –3 0 INPUT AMPLITUDE (dBFS) 0 11752-209 –10 2000 4000 6000 8000 10000 12000 14000 16000 OUTPUT CODE 11752-211 –2 SFDR (dBFS) SFDR (dBc) SNR (dBFS) SNR (dBc) 0 Figure 50. INL, fIN = 10.3 MHz Figure 48. SNR/SFDR vs. Analog Input Level, fIN = 170.3 MHz 0.6 100 0.4 SFDR 0.2 DNL (LSB) 80 70 0 SNR –0.2 60 50 –50 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 TEMPERATURE (°C) 90 –0.6 0 2000 4000 6000 8000 10000 12000 14000 16000 OUTPUT CODE Figure 51. DNL, fIN = 15 MHz Figure 49. SNR/SFDR vs. Temperature, fIN = 170.3 MHz Rev. C | Page 22 of 97 11752-212 –0.4 11752-210 SNR/SFDR (dBFS) 90 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 3.40 25000 L = 4, M = 2, F = 1 2.63 LSB rms 3.35 3.30 POWER DISSIPATION (W) NUMBER OF HITS 20000 15000 10000 3.25 3.20 3.15 3.10 3.05 3.00 5000 N–6 N–5 N–4 N–3 N–2 N–1 N N+1 N+2 N+3 N+4 N+5 N+6 CODE 3.40 L=4 M=2 F=1 3.30 3.25 3.20 10 20 30 40 50 60 70 TEMPERATURE (°C) 80 90 11752-214 POWER DISSIPATION (W) 3.35 0 750 800 850 900 950 1000 SAMPLE RATE (MHz) Figure 54. Power Dissipation vs. fS Figure 52. Input-Referred Noise Histogram 3.15 –50 –40 –30 –20 –10 2.90 700 Figure 53. Power Dissipation vs. Temperature Rev. C | Page 23 of 97 1050 1100 11752-215 0 11752-213 2.95 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet AD9680-820 AVDD1 = 1.25 V, AVDD1_SR = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, 1.7 V p-p full-scale differential input, AIN = −1.0 dBFS, default SPI settings, clock divider = 2, TA = 25°C, 128k FFT sample, unless otherwise noted. See Table 10 for recommended settings. 0 0 AIN = –1dBFS SNR = 67.2dBFS ENOB = 10.9BITS SFDR = 89dBFS BUFFER CONTROL 1 = 1.5× AIN = –1dBFS SNR = 65.1dBFS ENOB = 10.5 BITS SFDR = 79dBFS BUFFER CONTROL 1 = 6.5× –20 AMPLITUDE (dBFS) –40 –60 –80 –40 –60 –80 0 82 164 246 FREQUENCY (MHz) 328 410 –120 11752-507 –120 0 246 328 410 Figure 58. Single-Tone FFT with fIN = 450.3 MHz 0 0 AIN = –1dBFS SNR = 67.0dBFS ENOB = 10.8 BITS SFDR = 83dBFS BUFFER CONTROL 1 = 2.0× AIN = –1dBFS SNR = 64.0dBFS ENOB = 10.3 BITS SFDR = 79dBFS BUFFER CONTROL 1 = 6.5× –20 AMPLITUDE (dBFS) –20 –40 –60 –80 –100 –40 –60 –80 –120 0 82 164 246 328 410 FREQUENCY (MHz) 11752-508 –100 –120 0 82 164 246 328 410 11752-511 AMPLITUDE (dBFS) 164 FREQUENCY (MHz) Figure 55. Single-Tone FFT with fIN = 10.3 MHz 410 FREQUENCY (MHz) Figure 56. Single-Tone FFT with fIN = 170.3 MHz Figure 59. Single-Tone FFT with fIN = 765.3 MHz 0 0 AIN = –1dBFS SNR = 66.5dBFS ENOB = 10.7 BITS SFDR = 86dBFS BUFFER CONTROL 1 = 3.0× AIN = –1dBFS SNR = 63.4dBFS ENOB = 10.1 BITS SFDR = 74dBFS BUFFER CONTROL 1 = 8.5× –20 AMPLITUDE (dBFS) –20 –40 –60 –80 –100 –40 –60 –80 –100 –120 0 82 164 246 FREQUENCY (MHz) 328 410 11752-509 AMPLITUDE (dBFS) 82 11752-510 –100 –100 11752-512 AMPLITUDE (dBFS) –20 Figure 57. Single-Tone FFT with fIN = 340.3 MHz –120 0 82 164 246 328 FREQUENCY (MHz) Figure 60. Single-Tone FFT with fIN = 985.3 MHz Rev. C | Page 24 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 0 90 AIN = –1dBFS SNR = 62.0dBFS ENOB = 9.9 BITS SFDR = 76dBFS BUFFER CONTROL 1 = 6.5× 85 SFDR 80 –40 SNR/SFDR (dBFS) AMPLITUDE (dBFS) –20 –60 –80 75 70 SNR 65 60 –100 0 82 164 246 FREQUENCY (MHz) 328 410 50 500 Figure 61. Single-Tone FFT with fIN = 1205.3 MHz 800 850 900 Figure 64. SNR/SFDR vs. fS, fIN = 170.3 MHz; Buffer Control 1 (0x018) = 3.0× 0 95 AIN = –1dBFS SNR = 60.5dBFS ENOB = 9.5 BITS SFDR = 68dBFS BUFFER CONTROL 1 = 7.5× –20 90 85 –40 SNR/SFDR (dBFS) AMPLITUDE (dBFS) 700 750 650 SAMPLE RATE (MHz) 600 550 11752-516 –120 11752-513 55 –60 –80 80 75 70 65 60 –100 11752-517 450.3 420.3 390.3 360.3 340.7 330.3 301.3 270.3 240.3 210.5 50 180.3 410 170.3 328 150.3 246 95.3 164 FREQUENCY (MHz) 65.5 82 10.3 0 11752-514 –120 125.4 SFDR (3.0×) SNR (3.0×) 55 ANALOG INPUT FREQUENCY (MHz) Figure 65. SNR/SFDR vs. fIN; fIN < 450 MHz; Buffer Control 1 (0x018) = 3.0× Figure 62. Single-Tone FFT with fIN = 1720.3 MHz 85 0 AIN = –1dBFS SNR = 59.7dBFS ENOB = 9.5 BITS SFDR = 69dBFS BUFFER CONTROL 1 = 8.5× 80 SNR/SFDR (dBFS) 75 –40 –60 –80 70 65 60 –100 55 –120 50 450.3 0 82 164 246 328 FREQUENCY (MHz) 410 480.3 510.3 515.3 610.3 766.3 810.3 ANALOG INPUT FREQUENCY (MHz) Figure 66. SNR/SFDR vs. fIN; 450 MHz < fIN < 1 GHz; Buffer Control 1 (0x018) = 6.5× Figure 63. Single-Tone FFT with fIN = 1950.3 MHz Rev. C | Page 25 of 97 985.3 11752-018 SFDR (6.5×) SNR (6.5×) 11752-515 AMPLITUDE (dBFS) –20 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet 80 0 75 –20 AMPLITUDE (dBFS) SNR/SFDR (dBFS) AD9680 70 65 60 AIN1 AND AIN2 = –7dBFS SFDR = 87dBFS IMD2 = 92dBFS IMD3 = 87dBFS BUFFER CURRENT = 3.0× –40 –60 –80 –100 SFDR (6.5×) SNR (6.5×) 1022.3 1110.3 –120 1205.3 1315.3 1420.3 1510.3 ANALOG INPUT FREQUENCY (MHz) 0 11752-519 50 985.3 246 328 410 Figure 70. Two-Tone FFT; fIN1 = 338 MHz, fIN2 = 341 MHz 75 0 –20 SFDR/IMD3 (dBc AND dBFS) 70 65 60 55 –40 –60 –80 1950.3 11752-520 1720.3 1810.3 1920.3 1600.3 ANALOG INPUT FREQUENCY (MHz) –120 –87 –81 –75 –69 –63 –57 –51 –45 –39 –33 –27 –21 –15 –9 INPUT AMPLITUDE (dBFS) 11752-528 –100 SFDR (8.5×) SNR (8.5×) 50 1510.3 IMD3 (dBc) IMD3 (dBFS) SFDR (dBc) SFDR (dBFS) Figure 71. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184 MHz and fIN2 = 187 MHz Figure 68. SNR/SFDR vs. fIN; 1.5 GHz < fIN < 2 GHz; Buffer Control 1 (0x018) = 8.5× 0 0 AIN1 AND AIN2 = –7dBFS SFDR = 90dBFS IMD2 = 90dBFS IMD3 = 91dBFS BUFFER CURRENT = 3.0× –20 SFDR/IMD3 (dBc AND dBFS) –20 –40 –60 –80 –100 IMD3 (dBc) IMD3 (dBFS) SFDR (dBc) SFDR (dBFS) –40 –60 –80 –120 0 82 164 246 FREQUENCY (MHz) 328 410 11752-529 –100 –120 –87 –81 –75 –69 –63 –57 –51 –45 –39 –33 –27 –21 –15 –9 INPUT AMPLITUDE (dBFS) Figure 72. Two-Tone IMD3/SFDR vs. Input Amplitude (AIN) with fIN1 = 338 MHz and fIN2 = 341 MHz Figure 69. Two-Tone FFT; fIN1 = 184 MHz, fIN2 = 187 MHz Rev. C | Page 26 of 97 11752-535 SNR/SFDR (dBFS) 164 FREQUENCY (MHz) Figure 67. SNR/SFDR vs. fIN; 1 GHz < fIN < 1.5 GHz; Buffer Control 1 (0x018) = 6.5× AMPLITUDE (dBFS) 82 11752-527 55 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 2.5 105 2.0 90 1.5 SNR/SFDR (dBc AND dBFS) 120 75 1.0 INL (LSB) 60 45 30 0.5 0 –0.5 15 –1.0 SNR (dBc) SNR (dBFS) SFDR (dBc) SFDR (dBFS) –1.5 0 –5 –10 –15 –20 –25 –30 –35 –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 –95 –30 –2.0 0 2000 4000 8000 10000 6000 OUTPUT CODE 12000 14000 16000 11752-534 –15 11752-521 0 INPUT AMPLITUDE (dBFS) Figure 73. SNR/SFDR vs. Analog Input Level, fIN = 170.3 MHz Figure 75. INL, fIN = 10.3 MHz 90 0.25 SNR (dBFS) SFDR (dBFS) 0.20 85 0.15 DNL (LSB) 0.05 75 0 –0.05 –0.10 70 –0.15 –0.20 65 –30 –15 –5 5 15 25 TEMPERATURE (°C) 45 65 85 –0.30 0 2000 4000 6000 8000 10000 OUTPUT CODE 12000 Figure 76. DNL, fIN = 15 MHz Figure 74. SNR/SFDR vs. Temperature, fIN = 170.3 MHz Rev. C | Page 27 of 97 14000 16000 11752-530 –0.25 60 –45 11752-533 SNR/SFDR (dBFS) 0.10 80 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 3.1 1600000 2.46 LSB rms 1400000 3.0 2.9 POWER (W) 1000000 800000 600000 2.8 2.7 400000 11752-531 CODE 2.88 2.86 2.84 2.82 2.80 –5 5 15 25 TEMPERATURE (°C) 45 65 85 11752-532 2.78 –15 900 875 850 825 800 775 750 725 700 650 675 625 600 575 Figure 79. Power Dissipation vs. fS ; L = 4, M = 2, F = 1 for fS ≥ 625 MSPS and L = 2, M = 2, F = 2 for fS < 625 MSPS (Default SPI) 2.90 –30 550 SAMPLE RATE (MHz) Figure 77. Input-Referred Noise Histogram 2.76 –45 525 2.5 500 N – 10 N–9 N–8 N–7 N–6 N–5 N–4 N–3 N–2 N–1 N N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 N+9 N + 10 0 11752-522 2.6 200000 POWER (W) NUMBER OF HITS 1200000 Figure 78. Power Dissipation vs. Temperature Rev. C | Page 28 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 AD9680-500 AVDD1 = 1.25 V, AVDD1_SR = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, DVDD = 1.25 V, DRVDD = 1.25 V, SPIVDD = 1.8 V, 2.06 V p-p full-scale differential input, AIN = −1.0 dBFS, default SPI settings, clock divider = 2, TA = 25°C, 128k FFT sample, unless otherwise noted. See Table 10 for recommended settings. 0 0 AIN = −1dBFS SNR = 68.9dBFS ENOB = 10.9 BITS SFDR = 83dBFS BUFFER CONTROL 1 = 2.0× –20 –20 –40 AMPLITUDE (dBFS) –40 –60 –80 –60 –80 –100 –100 0 25 50 75 100 125 150 175 200 225 –140 11752-132 –140 250 FREQUENCY (MHz) 0 25 175 200 225 250 –40 AMPLITUDE (dBFS) –60 –80 –60 –80 –100 –120 –140 0 25 50 75 100 125 150 175 200 225 250 FREQUENCY (MHz) 11752-133 –120 –140 0 75 100 125 150 175 200 225 250 Figure 84. Single-Tone FFT with fIN = 765.3 MHz 0 AIN = −1dBFS SNR = 68.5dBFS ENOB = 10.9 BITS SFDR = 83dBFS BUFFER CONTROL 1 = 4.5× –20 50 FREQUENCY (MHz) Figure 81. Single-Tone FFT with fIN = 170.3 MHz 0 25 11752-136 AMPLITUDE (dBFS) 150 AIN = −1dBFS SNR = 64.7dBFS ENOB = 10.4 BITS SFDR = 80dBFS BUFFER CONTROL 1 = 5.0× –20 –100 AIN = −1dBFS SNR = 64.0dBFS ENOB = 10.3 BITS SFDR = 76dBFS BUFFER CONTROL 1 = 5.0× –20 –40 –40 AMPLITUDE (dBFS) AMPLITUDE (dBFS) 125 0 –40 –60 –80 –100 –120 –60 –80 –100 –120 0 25 50 75 100 125 150 175 200 225 FREQUENCY (MHz) 250 –140 11752-134 –140 100 Figure 83. Single-Tone FFT with fIN = 450.3 MHz AIN = −1dBFS SNR = 68.9dBFS ENOB = 11 BITS SFDR = 88dBFS BUFFER CONTROL 1 = 2.0× –20 75 FREQUENCY (MHz) Figure 80. Single-Tone FFT with fIN = 10.3 MHz 0 50 11752-135 –120 –120 0 25 50 75 100 125 150 175 200 225 FREQUENCY (MHz) Figure 82. Single-Tone FFT with fIN = 340.3 MHz Figure 85. Single-Tone FFT with fIN = 985.3 MHz Rev. C | Page 29 of 97 250 11752-137 AMPLITUDE (dBFS) AIN = −1dBFS SNR = 67.8dBFS ENOB = 10.8 BITS SFDR = 83dBFS BUFFER CONTROL 1 = 4.5× Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 95 0 AIN = −1dBFS SNR = 63.0dBFS ENOB = 10.0 BITS SFDR = 69dBFS BUFFER CONTROL 1 = 8.0× 90 SNR/SFDR (dBFS) –60 –80 80 75 –100 70 –120 65 –140 0 25 50 75 100 125 150 175 200 225 250 FREQUENCY (MHz) SNR 60 300 320 340 360 380 400 420 440 460 480 500 530 550 11752-138 AMPLITUDE (dBFS) SFDR 85 –40 SAMPLE FREQUENCY (MHz) Figure 86. Single-Tone FFT with fIN = 1310.3 MHz 11752-141 –20 Figure 89. SNR/SFDR vs. fS, fIN = 170.3 MHz; Buffer Control 1 = 2.0× 100 0 AIN = −1dBFS SNR = 61.5dBFS ENOB = 9.8 BITS SFDR = 69dBFS BUFFER CONTROL 1 = 8.0× –20 90 SNR/SFDR (dBFS) AMPLITUDE (dBFS) –40 –60 –80 80 70 –100 60 0 25 50 75 100 125 150 175 200 225 250 FREQUENCY (MHz) 50 10.3 11752-139 –140 2.0× SNR 2.0× SFDR 4.5× SNR 4.5× SFDR 95.3 150.3 180.3 240.3 301.3 340.7 390.3 450.3 ANALOG INPUT FREQUENCY (MHz) Figure 87. Single-Tone FFT with fIN = 1710.3 MHz 11752-142 –120 Figure 90. SNR/SFDR vs. fIN; fIN < 500 MHz; Buffer Control 1 (0x018) = 2.0× and 4.5× 0 100 AIN = −1dBFS SNR = 60.8dBFS ENOB = 9.6 BITS SFDR = 68dBFS BUFFER CONTROL 1 = 8.0× –20 90 SNR/SFDR (dBFS) –60 –80 80 70 –100 60 –140 0 25 50 75 100 125 150 175 200 225 FREQUENCY (MHz) 250 50 450.3 4.0× SNR 4.0× SFDR 8.0× SNR 8.0× SFDR 480.3 510.3 515.3 610.3 765.3 810.3 985.3 ANALOG INPUT FREQUENCY (MHz) Figure 91. SNR/SFDR vs. fIN; 500 MHz < fIN < 1 GHz; Buffer Control 1 (0x018) = 4.0× and 8.0× Figure 88. Single-Tone FFT with fIN = 1950.3 MHz Rev. C | Page 30 of 97 1010.3 11752-143 –120 11752-140 AMPLITUDE (dBFS) –40 Product Overview Design Resources Online Documentation Sample & Buy Discussion Data Sheet 80 0 7.0× SNR 7.0× SFDR 8.0× SNR 8.0× SFDR 70 65 60 –60 –80 1950.3 –120 –90 –84 –78 –72 –66 –60 –54 –48 –42 –36 –30 –24 –18 –12 11752-148 1205.3 1810.3 1410.3 1600.3 ANALOG INPUT FREQUENCY (MHz) 11752-144 50 1010.3 INPUT AMPLITUDE (dBFS) Figure 92. SNR/SFDR vs. fIN; 1 GHz < fIN < 2 GHz; Buffer Control 1 (0x018) = 7.0× and 8.0× Figure 95. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184 MHz and fIN2 = 187 MHz 0 0 AIN1 AND AIN2 = –7dBFS SFDR = 88dBFS IMD2 = 94dBFS IMD3 = 88dBFS BUFFER CONTROL 1 = 2.0× SFDR (dBc) SFDR (dBFS) IMD3 (dBc) IMD3 (dBFS) –20 SFDR/IMD3 (dBc AND dBFS) –20 –40 –60 –80 –40 –60 –80 0 50 100 150 FREQUENCY (MHz) 200 250 11752-146 –120 –120 –90 –72 –63 –54 –45 –36 100 SNR/SFDR (dBc AND dBFS) 90 –40 –60 –80 –100 80 70 60 50 40 30 20 10 SFDR (dBFS) SNR (dBFS) SFDR (dBc) SNR (dBc) 0 –10 200 250 –20 –90 11752-147 –120 100 150 FREQUENCY (MHz) –9 110 AIN1 AND AIN2 = –7dBFS SFDR = 88dBFS IMD2 = 88dBFS IMD3 = 89dBFS BUFFER CONTROL 1 = 4.5× 50 –18 Figure 96. Two-Tone IMD3/SFDR vs. Input Amplitude (AIN) with fIN1 = 338 MHz and fIN2 = 341 MHz 0 0 –27 AMPLITUDE (dBFS) Figure 93. Two-Tone FFT; fIN1 = 184 MHz, fIN2 = 187 MHz –20 –81 11752-149 –100 –100 –80 –70 –60 –50 –40 –30 –20 –10 INPUT AMPLITUDE (dBFS) Figure 94. Two-Tone FFT; fIN1 = 338 MHz, fIN2 = 341 MHz Figure 97. SNR/SFDR vs. Analog Input Level, fIN = 170.3 MHz Rev. C | Page 31 of 97 0 11752-150 AMPLITUDE (dBFS) –40 –100 55 AMPLITUDE (dBFS) SFDR (dBc) SFDR (dBFS) IMD3 (dBc) IMD3 (dBFS) –20 SFDR/IMD3 (dBc AND dBFS) 75 SNR/SFDR (dBFS) AD9680 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 95 900000 2.06 LSB RMS 800000 SFDR 700000 85 NUMBER OF HITS SNR/SFDR (dBFS) 90 80 75 600000 500000 400000 300000 200000 SNR 70 35 60 85 TEMPERATURE (°C) 0 N – 10 N–9 N–8 N–7 N–6 N–5 N–4 N–3 N–2 N–1 N N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 N+9 N + 10 10 11752-151 –15 OUTPUT CODE Figure 98. SNR/SFDR vs. Temperature, fIN = 170.3 MHz Figure 101. Input-Referred Noise Histogram 3.0 2.32 L=4 M=2 F=1 2.5 2.30 2.0 1.5 2.28 POWER (W) INL (LSB) 11752-154 100000 65 –40 1.0 0.5 0 2.26 2.24 –0.5 –1.0 2.22 0 2000 4000 6000 8000 10000 12000 14000 16000 OUTPUT CODE 2.20 –45 11752-152 –2.0 –35 –5 15 25 45 65 11752-155 –1.5 85 TEMPERATURE (°C) Figure 99. INL, fIN = 10.3 MHz Figure 102. Power Dissipation vs. Temperature 0.8 2.37 0.6 2.32 L = 4, M = 2, F = 1 L = 2, M = 2, F = 2 2.27 0.4 POWER (W) DNL (LSB) 2.22 0.2 0 –0.2 2.17 2.12 2.07 2.02 –0.4 1.97 –0.6 2000 4000 6000 8000 10000 12000 OUTPUT CODE 14000 16000 1.87 300 320 340 360 380 400 420 440 460 480 500 520 540 11752-153 0 SAMPLE RATE (MHz) Figure 103. Power Dissipation vs. fS Figure 100. DNL, fIN = 15 MHz Rev. C | Page 32 of 97 11752-156 1.92 –0.8 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 EQUIVALENT CIRCUITS AVDD3 AVDD3 AVDD3 3pF 1.5pF 200Ω EMPHASIS/SWING CONTROL (SPI) VCM BUFFER 200Ω 67Ω 28Ω 10pF 200Ω 400Ω DRVDD AVDD3 AVDD3 DATA+ SERDOUTx+ x = 0, 1, 2, 3 VIN–x DRGND OUTPUT DRIVER DATA– SERDOUTx– x = 0, 1, 2, 3 11752-011 AIN CONTROL (SPI) 3pF 1.5pF DRVDD DRGND 11752-014 67Ω 200Ω 28Ω VIN+x Figure 107. Digital Outputs Figure 104. Analog Inputs DVDD 1kΩ 25Ω CLK+ DGND 20kΩ LEVEL TRANSLATOR DVDD AVDD1 25Ω 20kΩ 20kΩ VCM = 0.85V VCM 1kΩ SYNCINB± PIN CONTROL (SPI) 11752-012 CLK– SYNCINB– VCM = 0.85V 20kΩ 11752-015 SYNCINB+ AVDD1 DGND Figure 105. Clock Inputs Figure 108. SYNCINB± Inputs AVDD1_SR 1kΩ SPIVDD ESD PROTECTED 20kΩ LEVEL TRANSLATOR AVDD1_SR SCLK 20kΩ SPIVDD 1kΩ 30kΩ 1kΩ ESD PROTECTED 11752-013 SYSREF– VCM = 0.85V 11752-016 SYSREF+ Figure 109. SCLK Input Figure 106. SYSREF± Inputs Rev. C | Page 33 of 97 Online Documentation Product Overview Design Resources Sample & Buy Discussion AD9680 Data Sheet SPIVDD ESD PROTECTED 30kΩ 1kΩ CSB 1kΩ PDWN/ STBY ESD PROTECTED 11752-017 ESD PROTECTED Figure 110. CSB Input Figure 113. PDWN/STBY Input SPIVDD ESD PROTECTED AVDD2 SDO ESD PROTECTED SPIVDD 1kΩ SDIO PDWN CONTROL (SPI) 11752-020 ESD PROTECTED SPIVDD SDI V_1P0 30kΩ 11752-018 V_1P0 PIN CONTROL (SPI) Figure 111. SDIO Input Figure 114. V_1P0 Input/Output SPIVDD ESD PROTECTED FD JESD LMFC FD_A/FD_B JESD SYNC~ TEMPERATURE DIODE (FD_A ONLY) FD_x PIN CONTROL (SPI) 11752-019 ESD PROTECTED Figure 112. FD_A/FD_B Outputs Rev. C | Page 34 of 97 11752-021 ESD PROTECTED ESD PROTECTED Product Overview Design Resources Online Documentation Discussion Data Sheet Sample & Buy AD9680 THEORY OF OPERATION The AD9680 has two analog input channels and four JESD204B output lane pairs. The ADC is designed to sample wide bandwidth analog signals of up to 2 GHz. The AD9680 is optimized for wide input bandwidth, high sampling rate, excellent linearity, and low power in a small package. The dual ADC cores feature a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC features wide bandwidth inputs supporting a variety of user-selectable input ranges. An integrated voltage reference eases design considerations. The AD9680 has several functions that simplify the AGC function in a communications receiver. The programmable threshold detector allows monitoring of the incoming signal power using the fast detect output bits of the ADC. If the input signal level exceeds the programmable threshold, the fast detect indicator goes high. Because this threshold indicator has low latency, the user can quickly turn down the system gain to avoid an overrange condition at the ADC input. The Subclass 1 JESD204B-based high speed serialized output data lanes can be configured in one-lane (L = 1), two-lane (L = 2), and four-lane (L = 4) configurations, depending on the sample rate and the decimation ratio. Multiple device synchronization is supported through the SYSREF± and SYNCINB± input pins. ADC ARCHITECTURE The architecture of the AD9680 consists of an input buffered pipelined ADC. The input buffer is designed to provide a termination impedance to the analog input signal. This termination impedance can be changed using the SPI to meet the termination needs of the driver/amplifier. The default termination value is set to 400 Ω. The equivalent circuit diagram of the analog input termination is shown in Figure 104. The input buffer is optimized for high linearity, low noise, and low power. The input buffer provides a linear high input impedance (for ease of drive) and reduces kickback from the ADC. The buffer is optimized for high linearity, low noise, and low power. The quantized outputs from each stage are combined into a final 14-bit result in the digital correction logic. The pipelined architecture permits the first stage to operate with a new input sample; at the same time, the remaining stages operate with the preceding samples. Sampling occurs on the rising edge of the clock. ANALOG INPUT CONSIDERATIONS The analog input to the AD9680 is a differential buffer. The internal common-mode voltage of the buffer is 2.05 V. The clock signal alternately switches the input circuit between sample mode and hold mode. When the input circuit is switched into sample mode, the signal source must be capable of charging the sample capacitors and settling within one-half of a clock cycle. A small resistor, in series with each input, can help reduce the peak transient current injected from the output stage of the driving source. In addition, low Q inductors or ferrite beads can be placed on each leg of the input to reduce high differential capacitance at the analog inputs and, thus, achieve the maximum bandwidth of the ADC. Such use of low Q inductors or ferrite beads is required when driving the converter front end at high IF frequencies. Either a differential capacitor or two single-ended capacitors can be placed on the inputs to provide a matching passive network. This ultimately creates a low-pass filter at the input, which limits unwanted broadband noise. For more information, refer to the AN-742 Application Note, the AN-827 Application Note, and the Analog Dialogue article “Transformer-Coupled Front-End for Wideband A/D Converters” (Volume 39, April 2005). In general, the precise values depend on the application. For best dynamic performance, the source impedances driving VIN+x and VIN−x must be matched such that common-mode settling errors are symmetrical. These errors are reduced by the common-mode rejection of the ADC. An internal reference buffer creates a differential reference that defines the span of the ADC core. Maximum SNR performance is achieved by setting the ADC to the largest span in a differential configuration. In the case of the AD9680, the available span is programmable through the SPI port from 1.46 V p-p to 2.06 V p-p differential, with 1.58 V p-p differential being the default for the AD9680-1250, 1.70 V p-p differential being the default for the AD9680-1000 and AD9680-820, and 2.06 V p-p differential being the default for the AD9680-500. Differential Input Configurations There are several ways to drive the AD9680, either actively or passively. However, optimum performance is achieved by driving the analog input differentially. For applications where SNR and SFDR are key parameters, differential transformer coupling is the recommended input configuration (see Figure 115 and Table 9) because the noise performance of most amplifiers is not adequate to achieve the true performance of the AD9680. For low to midrange frequencies, a double balun or double transformer network (see Figure 115 and Table 9) is recommended for optimum performance of the AD9680. For higher frequencies in the second or third Nyquist zones, it is better to remove some of the front-end passive components to ensure wideband operation (see Figure 115 and Table 9). Rev. C | Page 35 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 0.1µF R1 R3 R2 C1 ADC C2 R2 R1 0.1µF 0.1µF R3 C1 11752-168 BALUN NOTES 1. SEE TABLE 9 FOR COMPONENT VALUES. Figure 115. Differential Transformer-Coupled Configuration for AD9680 Table 9. Differential Transformer-Coupled Input Configuration Component Values Frequency Range DC to 250 MHz 250 MHz to 2 GHz DC to 410 MHz 410 MHz to 2 GHz DC to 500 MHz 500 MHz to 2 GHz DC to 625 MHz 625 MHz to 2 GHz AD9680-820 AD9680-1000 AD9680-1250 Transformer ETC1-1-13 BAL-0006/BAL-0006SMG ETC1-1-13 BAL-0006/BAL-0006SMG ETC1-1-13/BAL-0006SMG BAL-0006/BAL-0006SMG BAL-0006SMG BAL-0006SMG Input Common Mode The analog inputs of the AD9680 are internally biased to the common mode as shown in Figure 116. The common-mode buffer has a limited range in that the performance suffers greatly if the common-mode voltage drops by more than 100 mV. Therefore, in dc-coupled applications, set the common-mode voltage to 2.05 V, ±100 mV to ensure proper ADC operation. The full-scale voltage setting must be at a 1.7 V p-p differential if running in a dc-coupled application. Analog Input Buffer Controls and SFDR Optimization The AD9680 input buffer offers flexible controls for the analog inputs, such as input termination, buffer current, and input fullscale adjustment. All the available controls are shown in Figure 116. AVDD3 AVDD3 200Ω 200Ω AVDD3 3pF 1.5pF C2 (pF) 2 2 2 2 2 Open 2 Open The input buffer has many registers that set the bias currents and other settings for operation at different frequencies. These bias currents and settings can be changed to suit the input frequency range of operation. Register 0x018 controls the buffer bias current to help with the kickback from the ADC core. This setting can be scaled from a low setting of 1.0× to a high setting of 8.5×. The default setting is 3.0× for the AD9680-1000 and AD9680-820, and 2.0× for the AD9680-500. These settings are sufficient for operation in the first Nyquist zone for the products. When the input buffer current in Register 0x018 is set, the amount of current required by the AVDD3 supply changes. This relationship is shown in Figure 117. For a complete list of buffer current settings, see Table 36. VCM BUFFER 250 AD9680-1250, AD9680-1000, AND AD9680-820 200Ω 200Ω 67Ω 28Ω C1 (pF) 4 4 4 4 4 Open 4 Open Input Buffer Control Registers (0x018, 0x019, 0x01A, 0x935, 0x934, 0x11A) AVDD3 AVDD3 R3 (Ω) 10 10 10 10 10 0 15 0 300 400Ω 10pF R2 (Ω) 50 50 50 50 25 25 50 50 Using the 0x018, 0x019, 0x01A, 0x11A, 0x934, and 0x935 registers, the buffer behavior on each channel can be adjusted to optimize the SFDR over various input frequencies and bandwidths of interest. IAVDD3 (mA) 67Ω 28Ω VIN+x R1 (Ω) 10 10 10 10 25 25 10 10 3pF 1.5pF AIN CONTROL SPI REGISTERS (0x008, 0x015, 0x016, 0x018, 0x019, 0x01A, 0x11A, 0x934, 0x935) 11752-169 VIN–x Figure 116. Analog Input Controls 200 AD9680-500 150 100 50 1.5× 2.5× 3.5× 4.5× 5.5× 6.5× 7.5× 8.5× BUFFER CONTROL 1 SETTING Figure 117. IAVDD3 vs. Buffer Control 1 Setting in Register 0x018 Rev. C | Page 36 of 97 11752-341 Device AD9680-500 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 Figure 118, Figure 119, and Figure 120 show the SFDR vs. analog input frequency for various buffer settings for the AD9680-1250. The recommended settings shown in Table 10 were used to take the data while changing the contents of Register 0x018 only. 74 72 70 68 66 64 62 650MHz 750MHz 850MHz 60 58 1304.3 1512.3 1408.3 1616.3 1720.3 1824.3 11752-633 Register 0x11A is used when sampling in higher Nyquist zones (>500 MHz for the AD9680-1000). This setting enables the ADC sampling network to optimize the sampling and settling times internal to the ADC for high frequency operation. For frequencies greater than 500 MHz, it is recommended to operate the ADC core at a 1.46 V full-scale setting irrespective of the speed grade. This setting offers better SFDR without any significant penalty in SNR. 76 SFDR (dBFS) The 0x019, 0x01A, 0x11A, and 0x935 registers offer secondary bias controls for the input buffer for frequencies >500 MHz. Register 0x934 can be used to reduce input capacitance to achieve wider signal bandwidth but may result in slightly lower linearity and noise performance. These register settings do not impact the AVDD3 power as much as Register 0x018 does. For frequencies <500 MHz, it is recommended to use the default settings for these registers. Table 10 shows the recommended values for the buffer current control registers for various speed grades. 1928.3 INPUT FREQUENCY (MHz) Figure 120. Buffer Current Sweeps, AD9680-1250 (SFDR vs. IBUFF); 1300 MHz < fIN < 2000 MHz; Front-End Network Shown in Figure 115 Figure 121, Figure 122, and Figure 123 show the SFDR vs. analog input frequency for various buffer settings for the AD9680-1000. The recommended settings shown in Table 10 were used to take the data while changing the contents of Register 0x018 only. 90 85 250MHz 350MHz 450MHz 550MHz 80 SFDR (dBFS) SFDR (dBFS) 80 85 75 75 70 65 70 60 50 10 147.3 212.3 290.3 355.3 433.3 511.3 589.3 11752-631 60 10.3 55 667.3 INPUT FREQUENCY (MHz) Figure 118. Buffer Current Sweeps, AD9680-1250 (SFDR vs. IBUFF); fIN < 500 MHz; Front-End Network Shown in Figure 115 1.5× 3.0× 4.5× 60 110 160 210 260 310 360 410 460 ANALOG INPUT FREQUENCY (MHz) 11752-170 65 Figure 121. Buffer Current Sweeps, AD9680-1000 (SFDR vs. IBUFF); fIN < 500 MHz; Front-End Network Shown in Figure 115 85 4.0× 5.0× 6.0× 80 80 75 75 SFDR (dBFS) SFDR (dBFS) 70 70 65 60 55 65 50 680.3 758.3 45 40 503.4 836.3 914.3 992.3 1070.3 1148.3 1226.3 INPUT FREQUENCY (MHz) Figure 119. Buffer Current Sweeps, AD9680-1250 (SFDR vs. IBUFF); 600 MHz < fIN < 1300 MHz; Front-End Network Shown in Figure 115 Rev. C | Page 37 of 97 677.6 851.9 1026.2 1200.5 ANALOG INPUT FREQUENCY (MHz) 1374.8 11752-172 55 602.3 350MHz 450MHz 550MHz 650MHz 11752-632 60 Figure 122. Buffer Current Sweeps, AD9680-1000 (SFDR vs. IBUFF); 500 MHz < fIN < 1500 MHz; Front-End Network Shown in Figure 115 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet 80 95 75 90 70 85 80 65 SFDR (dBFS) SFDR (dBFS) AD9680 60 55 75 70 65 50 450.3 420.3 390.3 360.3 330.3 301.3 240.3 340.7 11752-524 1022.3 985.3 810.3 450.3 420.3 ANALOG INPUT FREQUENCY (MHz) 60 Figure 126. Buffer Current Sweeps, AD9680-820 (SFDR vs. IBUFF); 500 MHz < fIN < 1000 MHz; Front-End Network Shown in Figure 115 80 Figure 124. SNR/SFDR vs. Analog Input Level vs. Input Frequencies, AD9680-1000 70 SFDR (dBFS) 65 60 11752-525 1950.3 1920.3 1810.3 1720.3 50 1600.3 55 1510.3 Figure 125, Figure 126, and Figure 127 show the SFDR vs. analog input frequency for various buffer settings for the AD9680-820. The recommended settings shown in Table 10 were used to take the data while changing the contents of Register 0x018 only. 6.5× 7.5× 8.5× 75 1420.3 INPUT LEVEL (dBFS) 1315.3 55 –1 1205.3 –2 1110.3 55 –3 1.52GHz 1.65GHz 1.76GHz 1.9GHz 1.95GHz 50 1022.3 60 SNR (dBc) 65 65 270.3 3.5× 4.5× 5.5× 6.5× 7.5× 55 11752-174 SFDR (dBFS) 70 210.5 65 60 70 180.3 70 766.3 75 75 610.3 75 80 80 515.3 1.65GHz 1.52GHz 1.76GHz 1.95GHz 1.9GHz 85 510.3 80 ANALOG INPUT FREQUENCY (MHz) Figure 125. Buffer Current Sweeps, AD9680-820 (SFDR vs. IBUFF); fIN < 500 MHz; Front-End Network Shown in Figure 115 SFDR (dBFS) In certain high frequency applications, the SFDR can be improved by reducing the full-scale setting, as shown in Table 10. At high frequencies, the performance of the ADC core is limited by jitter. The SFDR can be improved by backing off of the full scale level. Figure 124 shows the SFDR and SNR vs. full-scale input level at different high frequencies for the AD9680-1000. 170.3 Figure 123. Buffer Current Sweeps, AD9680-1000 (SFDR vs. IBUFF); 1500 MHz < fIN < 2000 MHz; Front-End Network Shown in Figure 115 150.3 50 125.4 1889.8 480.3 1795.6 65.5 1701.5 ANALOG INPUT FREQUENCY (MHz) 95.3 1607.4 11752-523 55 10.3 40 1513.4 1.5× 2.0× 3.0× 4.5× 60 11752-173 45 4.5× 5.5× 6.5× 7.5× 8.5× ANALOG INPUT FREQUENCY (MHz) Figure 127. Buffer Current Sweeps, AD9680-820 (SFDR vs. IBUFF); 1000 MHz < fIN < 2000 MHz; Front-End Network Shown in Figure 115 Rev. C | Page 38 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 Figure 128, Figure 129, and Figure 130 show the SFDR vs. analog input frequency for various buffer settings for the AD9680-500. The recommended settings shown in Table 10 were used to take the data while changing the contents of Register 0x018 only. 95 4.0× 5.0× 6.0× 7.0× 8.0× 90 SFDR (dBFS) 85 100 90 80 75 70 65 450.3 60 510.3 480.3 515.3 610.3 765.3 810.3 985.3 ANALOG INPUT FREQUENCY (MHz) 50 95.3 80 150.3 180.3 240.3 301.3 340.7 390.3 ANALOG INPUT FREQUENCY (MHz) 450.3 75 Figure 128. Buffer Current Sweeps, AD9680-500 (SFDR vs. IBUFF); fIN < 500 MHz; Front-End Network Shown in Figure 115 Buffer Control 1 (0x018) = 1.0×, 1.5×, 2.0×, 3.0×, or 4.5× 70 SFDR (dBFS) 30 10.3 Figure 129. Buffer Current Sweeps, AD9680-500 (SFDR vs. IBUFF); 450 MHz < fIN < 1000 MHz; Front-End Network Shown in Figure 115 1.0× 1.5× 2.0× 3.0× 4.5× 11752-145 40 11752-175 70 65 60 55 50 45 40 1010.3 4.0× 5.0× 6.0× 7.0× 8.0× 1205.3 1410.3 1600.3 1810.3 1950.3 ANALOG INPUT FREQUENCY (MHz) Figure 130. Buffer Current Sweeps, AD9680-500 (SFDR vs. IBUFF); 1 GHz < fIN < 2 GHz; Front-End Network Shown in Figure 115 Rev. C | Page 39 of 97 11752-176 SFDR (dBFS) 80 Product Overview Design Resources Online Documentation Discussion AD9680 Sample & Buy Data Sheet Table 10. Recommended Register Settings for SFDR Optimization at Different Input Frequencies Product AD9680500 AD9680820 AD96801000 AD96801250 Frequency DC to 250 MHz 250 MHz to 500 MHz 500 MHz to 1 GHz 1 GHz to 2 GHz DC to 200 MHz DC to 410 MHz 500 MHz to 1 GHz 1 GHz to 2 GHz DC to 150 MHz DC to 500 MHz 500 MHz to 1 GHz 1 GHz to 2 GHz DC to 625 MHz >625 MHz Buffer Control 1 (0x018)— Buffer Current Control 0x20 (2.0×) 0x70 (4.5×) 0x80 (5.0×) 0xF0 (8.5×) 0x10 (1.5×) 0x40 (3.0×) 0x80 (5.0×) 0xF0 (8.5×) 0x10 (1.5×) 0x40 (3.0×) 0xA0 (6.0×) 0xD0 (7.5×) 0x50 (3.5×) 0xA0 (6.0×) Buffer Control 2 (0x019)— Buffer Bias Setting 0x60 (Setting 3) 0x60 (Setting 3) 0x40 (Setting 1) 0x40 (Setting 1) 0x40 (Setting 1) 0x40 (Setting 1) 0x40 (Setting 1) 0x40 (Setting 1) 0x50 (Setting 2) 0x50 (Setting 2) 0x60 (Setting 3) 0x70 (Setting 4) 0x50 (Setting 2) 0x50 (Setting 2) Buffer Control 3 (0x01A)— Buffer Bias Setting 0x0A (Setting 3) 0x0A (Setting 3) 0x08 (Setting 1) 0x08 (Setting 1) 0x09 (Setting 2) 0x09 (Setting 2) 0x08 (Setting 1) 0x08 (Setting 1) 0x09 (Setting 2) 0x09 (Setting 2) 0x09 (Setting 2) 0x09 (Setting 2) 0x09 (Setting 2) 0x09 (Setting 2) Buffer Control 4 (0x11A)— High Frequency Setting 0x00 (off) Buffer Control 5 (0x935)— Low Frequency Setting 0x04 (on) 0x00 (off) 0x04 (on) 0x00 (off) 0x00 (off) 0x00 (off) 0x00 (off) 0x00 (off) 0x04 (on) 0x00 (off) 0x04 (on) 0x00 (off) 0x00 (off) 0x00 (off) 0x00 (off) 0x00 (off) 0x04 (on) 0x00 (off) 0x04 (on) 0x20 (on) 0x00 (off) 0x20 (on) 0x00 (off) 0x00 (off) 0x04 (on) N/A3 0x00 (off) Input Full-Scale Range (0x025) 0x0C (2.06 V p-p) 0x0C (2.06 V p-p) 0x08 (1.46 V p-p) 0x08 (1.46 V p-p) 0x0A (1.70 V p-p) 0x0A (1.70 V p-p) 0x08 (1.46 V p-p) 0x08 (1.46 V p-p) 0x0A (1.70 V p-p) 0x0A (1.70 V p-p) 0x08 (1.46 V p-p) 0x08 (1.46 V p-p) 0x0A (1.58 V p-p) 0x08 (1.46 V p-p) Input FullScale Control (0x030) 0x04 Input Termination (0x016)1 0x0C/0x1C/… Input Capacitance (0x934) 0x1F 0x04 0x0C/0x1C/… 0x1F 0x18 0x0C/0x1C/… 0x1F or 0x002 0x18 0x0C/0x1C/… 0x1F or 0x001 0x14 0x0C/0x1C/… 0x1F 0x14 0x0C/0x1C/… 0x1F 0x18 0x0C/0x1C/… 0x1F or 0x002 0x18 0x0C/0x1C/… 0x1F or 0x001 0x18 0x0E/0x1E/… 0x1F 0x18 0x0E/0x1E/… 0x1F 0x18 0x0E/0x1E/… 0x1F or 0x001 0x18 0x0E/0x1E/… 0x1F or 0x001 0x18 0x0E/0x1E/… 0x1F 0x18 0x0E/0x1E/… 0x1F or 0x001 The input termination can be changed to accommodate the application with little or no impact to ac performance. The input capacitance can be set to 1.5 pF to achieve wider input bandwidth but results in slightly lower ac performance. 3 N/A means not applicable. 1 2 Rev. C | Page 40 of 97 Online Documentation Product Overview Design Resources Sample & Buy Discussion Data Sheet AD9680 The absolute maximum input swing allowed at the inputs of the AD9680 is 4.3 V p-p differential. Signals operating near or at this level can cause permanent damage to the ADC. VOLTAGE REFERENCE A stable and accurate 1.0 V voltage reference is built into the AD9680. This internal 1.0 V reference is used to set the fullscale input range of the ADC. The full-scale input range can be adjusted via the ADC Function Register 0x025. For more information on adjusting the input swing, see Table 36. Figure 131 shows the block diagram of the internal 1.0 V reference controls. the reference voltage. For more information on adjusting the full-scale level of the AD9680, refer to the Memory Map Register Table section. The use of an external reference may be necessary, in some applications, to enhance the gain accuracy of the ADC or to improve thermal drift characteristics. Figure 132 shows the typical drift characteristics of the internal 1.0 V reference. 1.0010 1.0009 1.0008 1.0007 V_1P0 VOLTAGE (V) Absolute Maximum Input Swing VIN+A/ VIN+B VIN–A/ VIN–B ADC CORE FULL-SCALE VOLTAGE ADJUST 1.0004 1.0003 1.0002 1.0001 1.0000 V_1P0 0.9998 –50 25 90 Figure 132. Typical V_1P0 Drift 11752-031 V_1P0 PIN CONTROL SPI REGISTER (0x025, 0x02, AND 0x024) Figure 131. Internal Reference Configuration and Controls The SPI Register 0x024 enables the user to either use this internal 1.0 V reference, or to provide an external 1.0 V reference. When using an external voltage reference, provide a 1.0 V reference. The full-scale adjustment is made using the SPI, irrespective of The external reference must be a stable 1.0 V reference. The ADR130 is a good option for providing the 1.0 V reference. Figure 133 shows how the ADR130 can be used to provide the external 1.0 V reference to the AD9680. The grayed out areas show unused blocks within the AD9680 while using the ADR130 to provide the external reference. INTERNAL V_1P0 GENERATOR ADR130 1 NC 2 GND SET 5 3 VIN 0.1µF 0 TEMPERATURE (°C) 11752-106 0.9999 INPUT FULL-SCALE RANGE ADJUST SPI REGISTER (0x025, 0x02, AND 0x024) INPUT 1.0005 FULL-SCALE VOLTAGE ADJUST NC 6 VOUT 4 V_1P0 0.1µF FULL-SCALE CONTROL Figure 133. External Reference Using ADR130 Rev. C | Page 41 of 97 11752-032 INTERNAL V_1P0 GENERATOR 1.0006 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet CLOCK INPUT CONSIDERATIONS Input Clock Divider For optimum performance, drive the AD9680 sample clock inputs (CLK+ and CLK−) with a differential signal. This signal is typically ac-coupled to the CLK+ and CLK− pins via a transformer or clock drivers. These pins are biased internally and require no additional biasing. The AD9680 contains an input clock divider with the ability to divide the Nyquist input clock by 1, 2, 4, and 8. The divider ratios can be selected using Register 0x10B. This is shown in Figure 137. Figure 134 shows a preferred method for clocking the AD9680. The low jitter clock source is converted from a single-ended signal to a differential signal using an RF transformer. 0.1µF 1:1Z CLK+ 100Ω CLK+ ADC CLK– 0.1µF CLK– ÷2 ÷4 ÷8 Figure 134. Transformer-Coupled Differential Clock Another option is to ac couple a differential CML or LVDS signal to the sample clock input pins, as shown in Figure 135 and Figure 136. REG 0x10B Figure 137. Clock Divider Circuit The AD9680 clock divider can be synchronized using the external SYSREF± input. A valid SYSREF± causes the clock divider to reset to a programmable state. This synchronization feature allows multiple devices to have their clock dividers aligned to guarantee simultaneous input sampling. See the Multichip Synchronization section for more information. 3.3V 71Ω 10pF 33Ω 33Ω Z0 = 50Ω 0.1µF ADC Z0 = 50Ω 0.1µF 11752-036 CLK+ CLK– Input Clock Divider ½ Period Delay Adjust The input clock divider inside the AD9680 provides phase delay in increments of ½ the input clock cycle. Register 0x10C can be programmed to enable this delay independently for each channel. Changing this register does not affect the stability of the JESD204B link. Figure 135. Differential CML Sample Clock 0.1µF 0.1µF LVDS DRIVER 100Ω CLK– CLOCK INPUT 50Ω1 150Ω CLK+ CLK+ 50Ω1 ADC Clock Fine Delay Adjust CLK– 0.1µF RESISTORS ARE OPTIONAL. 11752-037 0.1µF CLOCK INPUT 11752-038 50Ω 11752-035 CLOCK INPUT The maximum frequency at the CLK± inputs is 4 GHz. This is the limit of the divider. In applications where the clock input is a multiple of the sample clock, care must be taken to program the appropriate divider ratio into the clock divider before applying the clock signal. This ensures that the current transients during device startup are controlled. Figure 136. Differential LVDS Sample Clock Clock Duty Cycle Considerations Typical high speed ADCs use both clock edges to generate a variety of internal timing signals. As a result, these ADCs may be sensitive to clock duty cycle. Commonly, a 5% tolerance is required on the clock duty cycle to maintain dynamic performance characteristics. In applications where the clock duty cycle cannot be guaranteed to be 50%, a higher multiple frequency clock can be supplied to the device. The AD9680 can be clocked at 2 GHz with the internal clock divider set to 2. The output of the divider offers a 50% duty cycle, high slew rate (fast edge) clock signal to the internal ADC. See the Memory Map section for more details on using this feature. The AD9680 sampling edge instant can be adjusted by writing to Register 0x117 and Register 0x118. Setting Bit 0 of Register 0x117 enables the feature, and Bits[7:0] of Register 0x118 set the value of the delay. This value can be programmed individually for each channel. The clock delay can be adjusted from −151.7 ps to +150 ps in ~1.7 ps increments. The clock delay adjust takes effect immediately when it is enabled via SPI writes. Enabling the clock fine delay adjust in Register 0x117 causes a datapath reset. However, the contents of Register 0x118 can be changed without affecting the stability of the JESD204B link. Clock Jitter Considerations High speed, high resolution ADCs are sensitive to the quality of the clock input. The degradation in SNR at a given input frequency (fA) due only to aperture jitter (tJ) can be calculated by SNR = 20 × log 10 (2 × π × fA × tJ) In this equation, the rms aperture jitter represents the root mean square of all jitter sources, including the clock input, analog input signal, and ADC aperture jitter specifications. Rev. C | Page 42 of 97 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 IF undersampling applications are particularly sensitive to jitter (see Figure 138). 130 12.5fS 25fS 50fS 100fS 200fS 400fS 800fS 120 110 100 The AD9680 has a PDWN/STBY pin that can be used to configure the device in power-down or standby mode. The default operation is PDWN. The PDWN/STBY pin is a logic high pin. When in power-down mode, the JESD204B link is disrupted. The power-down option can also be set via Register 0x03F and Register 0x040. In standby mode, the JESD204B link is not disrupted and transmits zeros for all converter samples. This can be changed using Register 0x571, Bit 7 to select /K/ characters. 80 70 60 Temperature Diode 50 30 10 100 1000 10000 ANALOG INPUT FREQUENCY (MHz) 11752-039 40 Figure 138. Ideal SNR vs. Input Frequency and Jitter Treat the clock input as an analog signal in cases where aperture jitter may affect the dynamic range of the AD9680. Separate power supplies for clock drivers from the ADC output driver supplies to avoid modulating the clock signal with digital noise. If the clock is generated from another type of source (by gating, dividing, or other methods), retime the clock by the original clock at the last step. Refer to the AN-501 Application Note and the AN-756 Application Note for more in-depth information about jitter performance as it relates to ADCs. Figure 139 shows the estimated SNR of the AD9680-1000 across input frequency for different clock induced jitter values. The SNR can be estimated by using the following equation: − SNR JITTER − SNR ADC 10 SNR (dBFS) = 10log 10 + 10 10 70 The AD9680 contains a diode-based temperature sensor for measuring the temperature of the die. This diode can output a voltage and serve as a coarse temperature sensor to monitor the internal die temperature. The temperature diode voltage can be output to the FD_A pin using the SPI. Use Register 0x028, Bit 0 to enable or disable the diode. Register 0x028 is a local register. Channel A must be selected in the device index register (0x008) to enable the temperature diode readout. Configure the FD_A pin to output the diode voltage by programming Register 0x040[2:0]. See Table 36 for more information. The voltage response of the temperature diode (SPIVDD = 1.8 V) is shown in Figure 140. 0.90 0.85 DIODE VOLTAGE (V) 0.75 0.70 0.65 65 0.60 60 –55 –45 –35 –25 –15 –5 5 15 25 35 45 55 65 75 85 95 105 115 125 TEMPERATURE (°C) 55 50 45 10 Figure 140. Temperature Diode Voltage vs. Temperature 25fs 50fs 75fs 100f s 125f s 150f s 175f s 200f s 100 1K INPUT FREQUENCY (MHz) 10K 11752-526 SNR (dBFS) 0.80 Figure 139. Estimated SNR Degradation for the AD9680-1000 vs. Input Frequency and RMS Jitter Rev. C | Page 43 of 97 11752-353 SNR (dB) 90 Power-Down/Standby Mode Product Overview Design Resources Online Documentation Discussion Sample & Buy AD9680 Data Sheet ADC OVERRANGE AND FAST DETECT The operation of the upper threshold and lower threshold registers, along with the dwell time registers, is shown in Figure 141. In receiver applications, it is desirable to have a mechanism to reliably determine when the converter is about to be clipped. The standard overrange bit in the JESD204B outputs provides information on the state of the analog input that is of limited usefulness. Therefore, it is helpful to have a programmable threshold below full scale that allows time to reduce the gain before the clip actually occurs. In addition, because input signals can have significant slew rates, the latency of this function is of major concern. Highly pipelined converters can have significant latency. The AD9680 contains fast detect circuitry for individual channels to monitor the threshold and assert the FD_A and FD_B pins. The FD indicator is asserted if the input magnitude exceeds the value programmed in the fast detect upper threshold registers, located at Register 0x247 and Register 0x248. The selected threshold register is compared with the signal magnitude at the output of the ADC. The fast upper threshold detection has a latency of 28 clock cycles (maximum). The approximate upper threshold magnitude is defined by Upper Threshold Magnitude (dBFS) = 20 log (Threshold Magnitude/213) ADC OVERRANGE The FD indicators are not cleared until the signal drops below the lower threshold for the programmed dwell time. The lower threshold is programmed in the fast detect lower threshold registers, located at Register 0x249 and Register 0x24A. The fast detect lower threshold register is a 13-bit register that is compared with the signal magnitude at the output of the ADC. This comparison is subject to the ADC pipeline latency, but is accurate in terms of converter resolution. The lower threshold magnitude is defined by The ADC overrange indicator is asserted when an overrange is detected on the input of the ADC. The overrange indicator can be embedded within the JESD204B link as a control bit (when CSB > 0). The latency of this overrange indicator matches the sample latency. The AD9680 also records any overrange condition in any of the eight virtual converters. For more information on the virtual converters, refer to Figure 146. The overrange status of each virtual converter is registered as a sticky bit in Register 0x563. The contents of Register 0x563 can be cleared using Register 0x562, by toggling the bits corresponding to the virtual converter to set and reset position. Lower Threshold Magnitude (dBFS) = 20 log (Threshold Magnitude/213) For example, to set an upper threshold of −6 dBFS, write 0xFFF to Register 0x247 and Register 0x248. To set a lower threshold of −10 dBFS, write 0xA1D to Register 0x249 and Register 0x24A. FAST THRESHOLD DETECTION (FD_A AND FD_B) The FD bit is immediately set whenever the absolute value of the input signal exceeds the programmable upper threshold level. The FD bit is only cleared when the absolute value of the input signal drops below the lower threshold level for greater than the programmable dwell time. This feature provides hysteresis and prevents the FD bit from excessively toggling. The dwell time can be programmed from 1 to 65,535 sample clock cycles by placing the desired value in the fast detect dwell time registers, located at Register 0x24B and Register 0x24C. See the Memory Map section (Register 0x040, and Register 0x245 to Register 0x24C in Table 36) for more details. UPPER THRESHOLD DWELL TIME TIMER RESET BY RISE ABOVE LOWER THRESHOLD DWELL TIME FD_A OR FD_B Figure 141. Threshold Settings for FD_A and FD_B Signals Rev. C | Page 44 of 97 TIMER COMPLETES BEFORE SIGNAL RISES ABOVE LOWER THRESHOLD 11752-040 MIDSCALE LOWER THRESHOLD Online Documentation Product Overview Design Resources Data Sheet Discussion Sample & Buy AD9680 SIGNAL MONITOR The signal monitor block provides additional information about the signal being digitized by the ADC. The signal monitor computes the peak magnitude of the digitized signal. This information can be used to drive an AGC loop to optimize the range of the ADC in the presence of real-world signals. The results of the signal monitor block can be obtained either by reading back the internal values from the SPI port or by embedding the signal monitoring information into the JESD204B interface as special control bits. A global, 24-bit programmable period controls the duration of the measurement. Figure 142 shows the simplified block diagram of the signal monitor block. FROM MEMORY MAP SIGNAL MONITOR PERIOD REGISTER (SMPR) 0x271, 0x272, 0x273 DOWN COUNTER IS COUNT = 1? LOAD LOAD SIGNAL MONITOR HOLDING REGISTER TO SPORT OVER JESD204B AND MEMORY MAP 11752-087 CLEAR MAGNITUDE STORAGE REGISTER COMPARE A>B Figure 142. Signal Monitor Block The peak detector captures the largest signal within the observation period. The detector only observes the magnitude of the signal. The resolution of the peak detector is a 13-bit value, and the observation period is 24 bits and represents Peak Magnitude (dBFS) = 20log(Peak Detector Value/213) The magnitude of the input port signal is monitored over a programmable time period, which is determined by the signal monitor period register (SMPR). The peak detector function is enabled by setting Bit 1 of Register 0x270 in the signal monitor control register. The 24-bit SMPR must be programmed before activating this mode. After enabling peak detection mode, the value in the SMPR is loaded into a monitor period timer, which decrements at the decimated clock rate. The magnitude of the input signal is compared with the value in the internal magnitude storage register (not accessible to the user), and the greater of the two is updated as the current peak level. The initial value of the magnitude storage register is set to the current ADC input signal magnitude. This comparison continues until the monitor period timer reaches a count of 1. LOAD FROM INPUT converter output samples. The peak magnitude can be derived by using the following equation: When the monitor period timer reaches a count of 1, the 13-bit peak level value is transferred to the signal monitor holding register, which can be read through the memory map or output through the SPORT over the JESD204B interface. The monitor period timer is reloaded with the value in the SMPR, and the countdown restarts. In addition, the magnitude of the first input sample is updated in the magnitude storage register, and the comparison and update procedure, as explained previously, continues. Rev. C | Page 45 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet SPORT OVER JESD204B is to be inserted (CS = 1), only the most significant control bit is used (see Example Configuration 1 and Example Configuration 2 in Figure 143). To select the SPORT over JESD204B option, program Register 0x559, Register 0x55A, and Register 0x58F. See Table 36 for more information on setting these bits. The signal monitor data can also be serialized and sent over the JESD204B interface as control bits. These control bits must be deserialized from the samples to reconstruct the statistical data. The signal control monitor function is enabled by setting Bits[1:0] of Register 0x279 and Bit 1 of Register 0x27A. Figure 143 shows two different example configurations for the signal monitor control bit locations inside the JESD204B samples. A maximum of three control bits can be inserted into the JESD204B samples; however, only one control bit is required for the signal monitor. Control bits are inserted from MSB to LSB. If only one control bit Figure 144 shows the 25-bit frame data that encapsulates the peak detector value. The frame data is transmitted MSB first with five 5-bit subframes. Each subframe contains a start bit that can be used by a receiver to validate the deserialized data. Figure 145 shows the SPORT over JESD204B signal monitor data with a monitor period timer set to 80 samples. 16-BIT JESD204B SAMPLE SIZE (N' = 16) EXAMPLE CONFIGURATION 1 (N' = 16, N = 15, CS = 1) 1-BIT CONTROL BIT (CS = 1) 15-BIT CONVERTER RESOLUTION (N = 15) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 S[14] X S[13] X S[12] X S[11] X S[10] X S[9] X S[8] X S[7] X S[6] X S[5] X S[4] X S[3] X S[2] X S[1] X S[0] X CTRL [BIT 2] X SERIALIZED SIGNAL MONITOR FRAME DATA 16-BIT JESD204B SAMPLE SIZE (N' = 16) 14-BIT CONVERTER RESOLUTION (N = 14) 15 S[13] X 14 S[12] X 13 S[11] X 12 S[10] X 11 10 S[9] X 9 S[8] X 8 S[7] X 7 S[6] X 6 S[5] X 5 S[4] X 4 S[3] X S[2] X 3 S[1] X 2 1 0 S[0] X CTRL [BIT 2] X TAIL X SERIALIZED SIGNAL MONITOR FRAME DATA Figure 143. Signal Monitor Control Bit Locations 5-BIT SUB-FRAMES 5-BIT IDLE SUB-FRAME (OPTIONAL) 25-BIT FRAME IDLE 1 IDLE 1 IDLE 1 IDLE 1 IDLE 1 5-BIT IDENTIFIER START 0 SUB-FRAME ID[3] 0 ID[2] 0 ID[1] 0 ID[0] 1 5-BIT DATA MSB SUB-FRAME START 0 P[12] P[11] P[10] P[9] 5-BIT DATA SUB-FRAME START 0 P[8] P[7] P[6] P5] 5-BIT DATA SUB-FRAME START 0 P[4] P[3] P[2] P1] 5-BIT DATA LSB SUB-FRAME START 0 P[0] 0 0 0 P[] = PEAK MAGNITUDE VALUE 11752-089 EXAMPLE CONFIGURATION 2 (N' = 16, N = 14, CS = 1) Figure 144. SPORT over JESD204B Signal Monitor Frame Data Rev. C | Page 46 of 97 11752-088 1 CONTROL BIT 1 TAIL (CS = 1) BIT Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 SMPR = 80 SAMPLES (0x271 = 0x50; 0x272 = 0x00; 0x273 = 0x00) 80 SAMPLE PERIOD PAYLOAD #3 25-BIT FRAME (N) IDENT. DATA MSB DATA DATA DATA LSB IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE IDLE 80 SAMPLE PERIOD PAYLOAD #3 25-BIT FRAME (N + 1) IDENT. DATA MSB DATA DATA DATA LSB IDLE IDLE IDLE IDLE IDLE 80 SAMPLE PERIOD IDENT. DATA MSB DATA DATA DATA LSB IDLE IDLE IDLE IDLE IDLE Figure 145. SPORT over JESD204B Signal Monitor Example with Period = 80 Samples Rev. C | Page 47 of 97 11752-090 PAYLOAD #3 25-BIT FRAME (N + 2) Product Overview Design Resources Online Documentation Discussion Sample & Buy AD9680 Data Sheet DIGITAL DOWNCONVERTER (DDC) The AD9680 includes four digital downconverters (DDC 0 to DDC 3) that provide filtering and reduce the output data rate. This digital processing section includes an NCO, a half-band decimating filter, an FIR filter, a gain stage, and a complex-real conversion stage. Each of these processing blocks has control lines that allow it to be independently enabled and disabled to provide the desired processing function. The digital downconverter can be configured to output either real data or complex output data. The Chip Q ignore bit (Bit 5) in the chip application mode register (Register 0x200) controls the chip output muxing of all the DDC channels. When all DDC channels use real outputs, this bit must be set high to ignore all DDC Q output ports. When any of the DDC channels are set to use complex I/Q outputs, the user must clear this bit to use both DDC Output Port I and DDC Output Port Q. For more information, see Figure 154. The DDCs output a 16-bit stream. To enable this operation, the converter number of bits, N, is set to a default value of 16, even though the analog core only outputs 14 bits. In full bandwidth operation, the ADC outputs are the 14-bit word followed by two zeros, unless the tail bits are enabled. DDC GENERAL DESCRIPTION DDC I/Q INPUT SELECTION Each DDC block contains the following signal processing stages. The AD9680 has two ADC channels and four DDC channels. Each DDC channel has two input ports that can be paired to support both real or complex inputs through the I/Q crossbar mux. For real signals, both DDC input ports must select the same ADC channel (for example, DDC Input Port I = ADC Channel A, and Input Port Q = ADC Channel A). For complex signals, each DDC input port must select different ADC channels (for example, DDC Input Port I = ADC Channel A, and Input Port Q = ADC Channel B). The inputs to each DDC are controlled by the DDC input selection registers (Register 0x311, Register 0x331, Register 0x351, and Register 0x371). See Table 36 for information on how to configure the DDCs. DDC I/Q OUTPUT SELECTION Each DDC channel has two output ports that can be paired to support both real or complex outputs. For real output signals, only the DDC Output Port I is used (the DDC Output Port Q is invalid). For complex I/Q output signals, both DDC Output Port I and DDC Output Port Q are used. The I/Q outputs to each DDC channel are controlled by the DDC complex to real enable bit (Bit 3) in the DDC control registers (Register 0x310, Register 0x330, Register 0x350, and Register 0x370). The four DDC blocks are used to extract a portion of the full digital spectrum captured by the ADC(s). They are intended for IF sampling or oversampled baseband radios requiring wide bandwidth input signals. Frequency Translation Stage (Optional) The frequency translation stage consists of a 12-bit complex NCO and quadrature mixers that can be used for frequency translation of both real or complex input signals. This stage shifts a portion of the available digital spectrum down to baseband. Filtering Stage After shifting down to baseband, the filtering stage decimates the frequency spectrum using a chain of up to four half-band low-pass filters for rate conversion. The decimation process lowers the output data rate, which in turn reduces the output interface rate. Gain Stage (Optional) Due to losses associated with mixing a real input signal down to baseband, the gain stage compensates by adding an additional 0 dB or 6 dB of gain. Complex to Real Conversion Stage (Optional) When real outputs are necessary, the complex to real conversion stage converts the complex outputs back to real by performing an fS/4 mixing operation plus a filter to remove the complex component of the signal. Figure 146 shows the detailed block diagram of the DDCs implemented in the AD9680. Rev. C | Page 48 of 97 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 GAIN = 0dB OR 6dB COMPLEX TO REAL CONVERSION (OPTIONAL) COMPLEX TO REAL CONVERSION (OPTIONAL) COMPLEX TO REAL CONVERSION (OPTIONAL) COMPLEX TO REAL CONVERSION (OPTIONAL) HB1 FIR DCM = 2 GAIN = 0dB OR 6dB ADC SAMPLING AT fS GAIN = 0dB OR 6dB REAL/I GAIN = 0dB OR 6dB REAL/Q Q HB2 FIR DCM = BYPASS OR 2 NCO + MIXER (OPTIONAL) HB3 FIR DCM = BYPASS OR 2 I HB4 FIR DCM = BYPASS OR 2 DDC 0 REAL/I REAL/I CONVERTER 0 Q CONVERTER 1 SYSREF± Q CONVERTER 3 HB1 FIR DCM = 2 SYSREF± REAL/Q Q ADC SAMPLING AT fS HB1 FIR DCM = 2 HB2 FIR DCM = BYPASS OR 2 I HB3 FIR DCM = BYPASS OR 2 DDC 2 REAL/I NCO + MIXER (OPTIONAL) REAL/I REAL/I CONVERTER 2 REAL/I CONVERTER 4 OUTPUT INTERFACE REAL/Q Q HB2 FIR DCM = BYPASS OR 2 NCO + MIXER (OPTIONAL) HB3 FIR DCM = BYPASS OR 2 I HB4 FIR DCM = BYPASS OR 2 I/Q CROSSBAR MUX REAL/I HB4 FIR DCM = BYPASS OR 2 DDC 1 Q CONVERTER 5 SYSREF± SYSREF SYNCHRONIZATION CONTROL CIRCUITS REAL/I CONVERTER 6 Q CONVERTER 7 11752-041 REAL/Q Q HB1 FIR DCM = 2 NCO + MIXER (OPTIONAL) HB2 FIR DCM = BYPASS OR 2 I HB3 FIR DCM = BYPASS OR 2 REAL/I HB4 FIR DCM = BYPASS OR 2 DDC 3 SYSREF± Figure 146. DDC Detailed Block Diagram Figure 147 shows an example usage of one of the four DDC blocks with a real input signal and four half-band filters (HB4, HB3, HB2, and HB1). It shows both complex (decimate by 16) and real (decimate by 8) output options. the chip decimation ratio sample rate. Whenever the NCO frequency is set or changed, the DDC soft reset must be issued. If the DDC soft reset is not issued, the output may potentially show amplitude variations. When DDCs have different decimation ratios, the chip decimation ratio (Register 0x201) must be set to the lowest decimation ratio of all the DDC blocks. In this scenario, samples of higher decimation ratio DDCs are repeated to match Table 11, Table 12, Table 13, Table 14, and Table 15 show the DDC samples when the chip decimation ratio is set to 1, 2, 4, 8, or 16, respectively. Rev. C | Page 49 of 97 Design Resources Online Documentation Product Overview Discussion Sample & Buy AD9680 Data Sheet ADC ADC SAMPLING AT fS REAL REAL INPUT—SAMPLED AT fS BANDWIDTH OF INTEREST IMAGE –fS/2 –fS/3 –fS/4 REAL BANDWIDTH OF INTEREST fS/32 –fS/32 DC fS/16 –fS/16 –fS/8 FREQUENCY TRANSLATION STAGE (OPTIONAL) DIGITAL MIXER + NCO FOR fS/3 TUNING, THE FREQUENCY TUNING WORD = ROUND ((fS/3)/fS × 4096) = +1365 (0x555) fS/8 fS/4 fS/3 fS/2 I NCO TUNES CENTER OF BANDWIDTH OF INTEREST TO BASEBAND cos(ωt) REAL 12-BIT NCO 90° 0° –sin(ωt) Q DIGITAL FILTER RESPONSE –fS/2 –fS/3 –fS/4 fS/32 –fS/32 DC –fS/16 fS/16 –fS/8 BANDWIDTH OF INTEREST IMAGE (–6dB LOSS DUE TO NCO + MIXER) BANDWIDTH OF INTEREST (–6dB LOSS DUE TO NCO + MIXER) fS/8 fS/4 fS/3 fS/2 FILTERING STAGE HB4 FIR 4 DIGITAL HALF-BAND FILTERS (HB4 + HB3 + HB2 + HB1) I HALFBAND FILTER Q HALFBAND FILTER 2 2 HALFBAND FILTER 2 HALFBAND FILTER 2 HALFBAND FILTER HB3 FIR HB4 FIR HB1 FIR HB2 FIR HB3 FIR HALFBAND FILTER 2 HALFBAND FILTER 2 HALFBAND FILTER 2 I HB1 FIR HB2 FIR 2 Q 6dB GAIN TO COMPENSATE FOR NCO + MIXER LOSS COMPLEX (I/Q) OUTPUTS GAIN STAGE (OPTIONAL) DIGITAL FILTER RESPONSE I GAIN STAGE (OPTIONAL) Q 0dB OR 6dB GAIN COMPLEX TO REAL CONVERSION STAGE (OPTIONAL) fS/4 MIXING + COMPLEX FILTER TO REMOVE Q –fS/32 fS/32 DC –fS/16 fS/16 –fS/8 I REAL (I) OUTPUTS +6dB +6dB fS/8 2 +6dB 2 +6dB I Q –fS/32 fS/32 DC –fS/16 fS/16 DOWNSAMPLE BY 2 I DECIMATE BY 8 Q DECIMATE BY 16 0dB OR 6dB GAIN Q COMPLEX REAL/I TO REAL –fS/8 –fS/32 fS/32 DC –fS/16 fS/16 fS/8 Figure 147. DDC Theory of Operation Example (Real Input—Decimate by 16) Rev. C | Page 50 of 97 11752-042 6dB GAIN TO COMPENSATE FOR NCO + MIXER LOSS Product Overview Design Resources Online Documentation Data Sheet Discussion Sample & Buy AD9680 Table 11. DDC Samples, Chip Decimation Ratio = 1 Real (I) Output (Complex to Real Enabled) HB4 FIR + HB3 FIR + HB3 FIR + HB2 FIR + HB2 FIR + HB2 FIR + HB1 FIR HB1 FIR HB1 FIR HB1 FIR (DCM1 = 1) (DCM1 = 2) (DCM1 = 4) (DCM1 = 8) N N N N N+1 N+1 N+1 N+1 N+2 N N N N+3 N+1 N+1 N+1 N+4 N+2 N N N+5 N+3 N+1 N+1 N+6 N+2 N N N+7 N+3 N+1 N+1 N+8 N+4 N+2 N N+9 N+5 N+3 N+1 N + 10 N+4 N+2 N N + 11 N+5 N+3 N+1 N + 12 N+6 N+2 N N + 13 N+7 N+3 N+1 N + 14 N+6 N+2 N N + 15 N+7 N+3 N+1 N + 16 N+8 N+4 N+2 N + 17 N+9 N+5 N+3 N + 18 N+8 N+4 N+2 N + 19 N+9 N+5 N+3 N + 20 N + 10 N+4 N+2 N + 21 N + 11 N+5 N+3 N + 22 N + 10 N+4 N+2 N + 23 N + 11 N+5 N+3 N + 24 N + 12 N+6 N+2 N + 25 N + 13 N+7 N+3 N + 26 N + 12 N+6 N+2 N + 27 N + 13 N+7 N+3 N + 28 N + 14 N+6 N+2 N + 29 N + 15 N+7 N+3 N + 30 N + 14 N+6 N+2 N + 31 N + 15 N+7 N+3 1 Complex (I/Q) Outputs (Complex to Real Disabled) HB4 FIR + HB3 FIR + HB3 FIR + HB2 FIR + HB2 FIR + HB2 FIR + HB1 FIR HB1 FIR HB1 FIR HB1 FIR (DCM1 = 2) (DCM1 = 4) (DCM1 = 8) (DCM1 = 16) N N N N N+1 N+1 N+1 N+1 N N N N N+1 N+1 N+1 N+1 N+2 N N N N+3 N+1 N+1 N+1 N+2 N N N N+3 N+1 N+1 N+1 N+4 N+2 N N N+5 N+3 N+1 N+1 N+4 N+2 N N N+5 N+3 N+1 N+1 N+6 N+2 N N N+7 N+3 N+1 N+1 N+6 N+2 N N N+7 N+3 N+1 N+1 N+8 N+4 N+2 N N+9 N+5 N+3 N+1 N+8 N+4 N+2 N N+9 N+5 N+3 N+1 N + 10 N+4 N+2 N N + 11 N+5 N+3 N+1 N + 10 N+4 N+2 N N + 11 N+5 N+3 N+1 N + 12 N+6 N+2 N N + 13 N+7 N+3 N+1 N + 12 N+6 N+2 N N + 13 N+7 N+3 N+1 N + 14 N+6 N+2 N N + 15 N+7 N+3 N+1 N + 14 N+6 N+2 N N + 15 N+7 N+3 N+1 DCM means decimation. Rev. C | Page 51 of 97 Product Overview Online Documentation Design Resources AD9680 Discussion Sample & Buy Data Sheet Table 12. DDC Samples, Chip Decimation Ratio = 2 Real (I) Output (Complex to Real Enabled) HB4 FIR + HB3 FIR + HB3 FIR + HB2 FIR + HB2 FIR + HB2 FIR + HB1 FIR HB1 FIR HB1 FIR (DCM1 = 2) (DCM1 = 4) (DCM1 = 8) N N N N+1 N+1 N+1 N N N+2 N+1 N+1 N+3 N+2 N N+4 N+3 N+1 N+5 N+2 N N+6 N+3 N+1 N+7 N+4 N+2 N+8 N+5 N+3 N+9 N + 4 N+2 N + 10 N + 5 N+3 N + 11 N + 6 N+2 N + 12 N+7 N+3 N + 13 N+6 N+2 N + 14 N+7 N+3 N + 15 1 Complex (I/Q) Outputs (Complex to Real Disabled) HB4 FIR + HB3 FIR + HB3 FIR + HB2 FIR + HB2 FIR + HB2 FIR + HB1 FIR HB1 FIR HB1 FIR HB1 FIR (DCM1 = 2) (DCM1 = 4) (DCM1 = 8) (DCM1 = 16) N N N N N+1 N+1 N+1 N+1 N N N N+2 N+1 N+1 N+1 N+3 N+2 N N N+4 N+3 N+1 N+1 N+5 N+2 N N N+6 N+3 N+1 N+1 N+7 N+4 N+2 N N+8 N+5 N+3 N+1 N+9 N + 4 N + 2 N N + 10 N + 5 N + 3 N+1 N + 11 N + 6 N + 2 N N + 12 N+7 N+3 N+1 N + 13 N+6 N+2 N N + 14 N+7 N+3 N+1 N + 15 DCM means decimation. Table 13. DDC Samples, Chip Decimation Ratio = 4 Real (I) Output (Complex to Real Enabled) HB4 FIR + HB3 FIR + HB3 FIR + HB2 FIR + HB2 FIR + HB1 FIR HB1 FIR (DCM1 = 4) (DCM1 = 8) N N N+1 N+1 N N+2 N+1 N+3 N+2 N+4 N+3 N+5 N+2 N+6 N+3 N+7 1 Complex (I/Q) Outputs (Complex to Real Disabled) HB4 FIR + HB3 FIR + HB2 FIR + HB1 FIR HB3 FIR + HB2 FIR + HB2 FIR + HB1 FIR (DCM1 = 4) HB1 FIR (DCM1 = 8) (DCM1 = 16) N N N N+1 N+1 N+1 N N N+2 N+1 N+1 N+3 N+2 N N+4 N+3 N+1 N+5 N+2 N N+6 N+3 N+1 N+7 DCM means decimation. Table 14. DDC Samples, Chip Decimation Ratio = 8 Real (I) Output (Complex to Real Enabled) HB4 FIR + HB3 FIR + HB2 FIR + HB1 FIR (DCM1 = 8) N N+1 N+2 N+3 N+4 N+5 N+6 N+7 1 Complex (I/Q) Outputs (Complex to Real Disabled) HB3 FIR + HB2 FIR + HB1 FIR HB4 FIR + HB3 FIR + HB2 FIR + (DCM1 = 8) HB1 FIR (DCM1 = 16) N N N+1 N+1 N N+2 N+1 N+3 N+2 N+4 N+3 N+5 N+2 N+6 N+3 N+7 DCM means decimation. Rev. C | Page 52 of 97 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 Table 15. DDC Samples, Chip Decimation Ratio = 16 Real (I) Output (Complex to Real Enabled) HB4 FIR + HB3 FIR + HB2 FIR + HB1 FIR (DCM1 = 16) Not applicable Not applicable Not applicable Not applicable 1 Complex (I/Q) Outputs (Complex to Real Disabled) HB4 FIR + HB3 FIR + HB2 FIR + HB1 FIR (DCM1 = 16) N N+1 N+2 N+3 DCM means decimation. If the chip decimation ratio is set to decimate by 4, DDC 0 is set to use HB2 + HB1 filters (complex outputs decimate by 4), and DDC 1 is set to use HB4 + HB3 + HB2 + HB1 filters (real outputs decimate by 8), then DDC 1 repeats its output data two times for every one DDC 0 output. The resulting output samples are shown in Table 16. Table 16. DDC Output Samples when Chip DCM1 = 4, DDC 0 DCM1 = 4 (Complex), and DDC 1 DCM1 = 8 (Real) DDC Input Samples N N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 N+9 N + 10 N + 11 N + 12 N + 13 N + 14 N + 15 1 Output Port I I0 [N] DDC 0 Output Port Q Q0 [N] Output Port I I1 [N] DDC 1 Output Port Q Not applicable I0 [N + 1] Q0 [N + 1] I1 [N + 1] Not applicable I0 [N + 2] Q0 [N + 2] I1 [N] Not applicable I0 [N + 3] Q0 [N + 3] I1 [N + 1] Not applicable DCM means decimation. Rev. C | Page 53 of 97 Design Resources Online Documentation Product Overview Discussion Sample & Buy AD9680 Data Sheet FREQUENCY TRANSLATION FREQUENCY TRANSLATION GENERAL DESCRIPTION Variable IF Mode Frequency translation is accomplished by using a 12-bit complex NCO along with a digital quadrature mixer. The frequency translation translates either a real or complex input signal from an intermediate frequency (IF) to a baseband complex digital output (carrier frequency = 0 Hz). NCO and mixers are enabled. NCO output frequency can be used to digitally tune the IF frequency. 0 Hz IF (ZIF) Mode Mixers are bypassed and the NCO is disabled. fS/4 Hz IF Mode The frequency translation stage of each DDC can be controlled individually and supports four different IF modes using Bits[5:4] of the DDC control registers (Register 0x310, Register 0x330, Register 0x350, and Register 0x370). These IF modes are Test Mode Input samples are forced to 0.999 to positive full scale. NCO is enabled. This test mode allows the NCOs to directly drive the decimation filters. Variable IF mode 0 Hz IF (ZIF) mode fS/4 Hz IF mode Test mode Figure 148 and Figure 149 show examples of the frequency translation stage for both real and complex inputs. NCO FREQUENCY TUNING WORD (FTW) SELECTION 12-BIT NCO FTW = MIXING FREQUENCY/ADC SAMPLE RATE × 4096 I ADC + DIGITAL MIXER + NCO REAL INPUT—SAMPLED AT fS REAL ADC SAMPLING AT fS cos(ωt) REAL 12-BIT NCO 90° 0° COMPLEX –sin(ωt) Q BANDWIDTH OF INTEREST BANDWIDTH OF INTEREST IMAGE –fS/2 –fS/3 –fS/4 –fS/8 fS/32 –fS/32 DC –fS/16 fS/16 fS/8 fS/4 fS/3 fS/2 –6dB LOSS DUE TO NCO + MIXER 12-BIT NCO FTW = ROUND ((fS/3)/fS × 4096) = +1365 (0x555) POSITIVE FTW VALUES –fS/32 DC fS/32 12-BIT NCO FTW = ROUND ((fS/3)/fS × 4096) = –1365 (0xAAB) –fS/32 NEGATIVE FTW VALUES DC fS/32 Figure 148. DDC NCO Frequency Tuning Word Selection—Real Inputs Rev. C | Page 54 of 97 11752-043 • • • • Mixers and NCO are enabled in special down mixing by fS/4 mode to save power. Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 NCO FREQUENCY TUNING WORD (FTW) SELECTION 12-BIT NCO FTW = MIXING FREQUENCY/ADC SAMPLE RATE × 4096 QUADRATURE ANALOG MIXER + 2 ADCs + QUADRATURE DIGITAL REAL MIXER + NCO COMPLEX INPUT—SAMPLED AT fS QUADRATURE MIXER ADC SAMPLING AT fS I + I I Q Q 90° PHASE 12-BIT NCO 90° 0° Q Q ADC SAMPLING AT fS Q Q I I – –sin(ωt) I I + COMPLEX Q + BANDWIDTH OF INTEREST IMAGE DUE TO ANALOG I/Q MISMATCH –fS/3 –fS/4 –fS/32 fS/32 –fS/16 fS/16 DC –fS/8 fS/8 fS/4 fS/3 fS/2 12-BIT NCO FTW = ROUND ((fS/3)/fS × 4096) = +1365 (0x555) POSITIVE FTW VALUES –fS/32 fS/32 11752-044 –fS/2 DC Figure 149. DDC NCO Frequency Tuning Word Selection—Complex Inputs DDC NCO PLUS MIXER LOSS AND SFDR Setting Up the NCO FTW and POW When mixing a real input signal down to baseband, 6 dB of loss is introduced in the signal due to filtering of the negative image. An additional 0.05 dB of loss is introduced by the NCO. The total loss of a real input signal mixed down to baseband is 6.05 dB. For this reason, it is recommended that the user compensate for this loss by enabling the additional 6 dB of gain in the gain stage of the DDC to recenter the dynamic range of the signal within the full scale of the output bits. The NCO frequency value is given by the 12-bit twos complement number entered in the NCO FTW. Frequencies between −fS/2 and fS/2 (fS/2 excluded) are represented using the following frequency words: When mixing a complex input signal down to baseband, the maximum value each I/Q sample can reach is 1.414 × full scale after it passes through the complex mixer. To avoid overrange of the I/Q samples and to keep the data bitwidths aligned with real mixing, 3.06 dB of loss (0.707 × full scale) is introduced in the mixer for complex signals. An additional 0.05 dB of loss is introduced by the NCO. The total loss of a complex input signal mixed down to baseband is −3.11 dB. The worst case spurious signal from the NCO is greater than 102 dBc SFDR for all output frequencies. NUMERICALLY CONTROLLED OSCILLATOR The AD9680 has a 12-bit NCO for each DDC that enables the frequency translation process. The NCO allows the input spectrum to be tuned to dc, where it can be effectively filtered by the subsequent filter blocks to prevent aliasing. The NCO can be set up by providing a frequency tuning word (FTW) and a phase offset word (POW). • • • 0x800 represents a frequency of –fS/2. 0x000 represents dc (frequency is 0 Hz). 0x7FF represents a frequency of +fS/2 – fS/212. The NCO frequency tuning word can be calculated using the following equation: Mod( fC , f S ) NCO _ FTW = round 212 fS where: NCO_FTW is a 12-bit twos complement number representing the NCO FTW. fS is the AD9680 sampling frequency (clock rate) in Hz. fC is the desired carrier frequency in Hz. Mod( ) is a remainder function. For example, Mod(110,100) = 10, and for negative numbers, Mod(–32, 10) = –2. round( ) is a rounding function. For example, round(3.6) = 4, and for negative numbers, round(–3.4)= –3. Note that this equation applies to the aliasing of signals in the digital domain (that is, aliasing introduced when digitizing analog signals). Rev. C | Page 55 of 97 Product Overview Design Resources Online Documentation AD9680 Mod(416.667,1250 NCO _ FTW = round 212 = 1365 MHz 1250 Two methods can be used to synchronize multiple PAWs within the chip: • This, in turn, converts to 0x555 in the 12-bit twos complement representation for NCO_FTW. The actual carrier frequency can be calculated based on the following equation: NCO _ FTW × f S = 416.56 MHz 212 • A 12-bit POW is available for each NCO to create a known phase relationship between multiple AD9680 chips or individual DDC channels inside one AD9680. The following procedure must be followed to update the FTW and/or POW registers to ensure proper operation of the NCO: • • • Sample & Buy Data Sheet For example, if the ADC sampling frequency (fS) is 1250 MSPS and the carrier frequency (fC) is 416.667 MHz, fC − actual = Discussion Write to the FTW registers for all the DDCs. Write to the POW registers for all the DDCs. Synchronize the NCOs either through the DDC soft reset bit accessible through the SPI, or through the assertion of the SYSREF± pin. Note that the NCOs must be synchronized either through SPI or through the SYSREF± pin after all writes to the FTW or POW registers have completed. This synchronization is necessary to ensure the proper operation of the NCO. NCO Synchronization Each NCO contains a separate phase accumulator word (PAW) that determines the instantaneous phase of the NCO. The initial reset value of each PAW is determined by the POW described in the Setting Up the NCO FTW and POW section. The phase increment value of each PAW is determined by the FTW. Using the SPI. The DDC NCO soft reset bit in the DDC synchronization control register (Register 0x300, Bit 4) can be used to reset all the PAWs in the chip. This is accomplished by toggling the DDC NCO soft reset bit. This method can only be used to synchronize DDC channels within the same AD9680 chip. Using the SYSREF± pin. When the SYSREF± pin is enabled in the SYSREF± control registers (Register 0x120 and Register 0x121), and the DDC synchronization is enabled in Bits[1:0] in the DDC synchronization control register (Register 0x300), any subsequent SYSREF± event resets all the PAWs in the chip. This method can be used to synchronize DDC channels within the same AD9680 chip, or DDC channels within separate AD9680 chips. Mixer The NCO is accompanied by a mixer, whose operation is similar to an analog quadrature mixer. The mixer performs the downconversion of input signals (real or complex) by using the NCO frequency as a local oscillator. For real input signals, this mixer performs a real mixer operation (with two multipliers). For complex input signals, the mixer performs a complex mixer operation (with four multipliers and two adders). The mixer adjusts its operation based on the input signal (real or complex) provided to each individual channel. The selection of real or complex inputs can be controlled individually for each DDC block by using Bit 7 of the DDC control register (Register 0x310, Register 0x330, Register 0x350, and Register 0x370). Rev. C | Page 56 of 97 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 FIR FILTERS FIR FILTERS GENERAL DESCRIPTION There are four sets of decimate-by-2, low-pass, half-band, finite impulse response (FIR) filters (HB1 FIR, HB2 FIR, HB3 FIR, and HB4 FIR, shown in Figure 146). These filters follow the frequency translation stage. After the carrier of interest is tuned down to dc (carrier frequency = 0 Hz), these filters efficiently lower the sample rate while providing sufficient alias rejection from unwanted adjacent carriers around the bandwidth of interest. HB1 FIR is always enabled and cannot be bypassed. The HB2, HB3, and HB4 FIR filters are optional and can be bypassed for higher output sample rates. Table 17 shows the different bandwidth options by including different half-band filters. In all cases, the DDC filtering stage of the AD9680 provides less than −0.001 dB of pass-band ripple and >100 dB of stop-band alias rejection. Table 18 shows the amount of stop-band alias rejection for multiple pass-band ripple/cutoff points. The decimation ratio of the filtering stage of each DDC can be controlled individually through Bits[1:0] of the DDC control registers (0x310, 0x330, 0x350, and 0x370). Table 17. DDC Filter Characteristics ADC Sample Rate (MSPS) 1250 1000 820 500 1 Half Band Filter Selection HB1 Real Output Output Sample Decimation Rate Ratio (MSPS) 1 1250 HB1 + HB2 2 625 HB1 + HB2 + HB3 HB1 + HB2 + HB3 + HB4 HB1 4 312.5 8 156.25 1 1000 HB1 + HB2 2 500 HB1 + HB2 + HB3 HB1 + HB2 + HB3 + HB4 HB1 4 250 8 125 1 820 HB1 + HB2 2 410 HB1 + HB2 + HB3 HB1 + HB2 + HB3 + HB4 HB1 4 205 8 102.5 1 500 HB1 + HB2 2 250 HB1 + HB2 + HB3 HB1 + HB2 + HB3 + HB4 4 125 8 62.5 Complex (I/Q) Output Output Sample Decimation Rate Ratio (MSPS) 2 625 (I) + 625 (Q) 4 312.5 (I) + 312.5 (Q) 8 156.25 (I) + 156.25 (Q) 16 78.125 (I) + 78.125 (Q) 2 500 (I) + 500 (Q) 4 250 (I) + 250 (Q) 8 125 (I) + 125 (Q) 16 62.5 (I) + 62.5 (Q) 2 410 (I) + 410 (Q) 4 205 (I) + 205 (Q) 8 102.5 (I) + 102.5 (Q) 16 51.25 (I) + 51.25 (Q) 2 250 (I) + 250 (Q) 4 125 (I) + 125 (Q) 8 62.5 (I) + 62.5 (Q) 16 31.25 (I) + 31.25 (Q) Ideal SNR improvement due to oversampling and filtering = 10log(bandwidth/(fS/2)). Rev. C | Page 57 of 97 Alias Protected Bandwidth (MHz) 481.25 Ideal SNR Improvement (dB)1 1 240.62 4 120.31 7 60.15 10 385.0 1 192.5 4 96.3 7 48.1 10 315.7 1 157.8 4 78.9 7 39.4 10 192.5 1 96.3 4 48.1 7 24.1 10 PassBand Ripple (dB) <−0.001 Alias Rejection (dB) >100 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet Table 18. DDC Filter Alias Rejection Alias Rejection (dB) >100 90 85 63.3 25 19.3 10.7 1 Pass-Band Ripple/ Cutoff Point (dB) <−0.001 <−0.001 <−0.001 <−0.006 −0.5 −1.0 −3.0 Alias Protected Bandwidth for Complex (I/Q) Outputs1 <77% × fOUT <77.4% × fOUT <77.8% × fOUT <80% × fOUT 88.8% × fOUT 91.2% × fOUT 96% × fOUT Alias Protected Bandwidth for Real (I) Outputs1 <38.5% × fOUT <38.7% × fOUT <38.9% × fOUT <40% × fOUT 44.4% × fOUT 45.6% × fOUT 48% × fOUT fOUT is the ADC input sample rate fS/DDC decimation ratio. HALF-BAND FILTERS HB3 Filter The AD9680 offers four half-band filters to enable digital signal processing of the ADC converted data. These half-band filters are bypassable and can be individually selected. The second decimate-by-2, half-band, low-pass, FIR filter (HB3) uses an 11-tap, symmetrical, fixed coefficient filter implementation, optimized for low power consumption. The HB3 filter is only used when complex outputs (decimate by 8 or 16) or real outputs (decimate by 4 or 8) are enabled; otherwise, the filter is bypassed. Table 20 and Figure 151 show the coefficients and response of the HB3 filter. The first decimate-by-2, half-band, low-pass FIR filter (HB4) uses an 11-tap, symmetrical, fixed-coefficient filter implementation, optimized for low power consumption. The HB4 filter is only used when complex outputs (decimate by 16) or real outputs (decimate by 8) are enabled; otherwise, the filter is bypassed. Table 19 and Figure 150 show the coefficients and response of the HB4 filter. Table 19. HB4 Filter Coefficients Normalized Coefficient 0.006042 0 −0.049316 0 0.293273 0.500000 Decimal Coefficient (15-Bit) 99 0 −808 0 4805 8192 0 –20 –40 Normalized Coefficient 0.006554 0 −0.050819 0 0.294266 0.500000 Decimal Coefficient (18-Bit) 859 0 −6661 0 38,570 65,536 0 –20 –40 –60 –80 –60 –100 –80 –120 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 NORMALIZED FREQUENCY (× π RAD/SAMPLE) –100 Figure 151. HB3 Filter Response –120 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 NORMALIZED FREQUENCY (× π RAD/SAMPLE) 11752-045 MAGNITUDE (dB) HB3 Coefficient Number C1, C11 C2, C10 C3, C9 C4, C8 C5, C7 C6 MAGNITUDE (dB) HB4 Coefficient Number C1, C11 C2, C10 C3, C9 C4, C8 C5, C7 C6 Table 20. HB3 Filter Coefficients Figure 150. HB4 Filter Response Rev. C | Page 58 of 97 11752-046 HB4 Filter Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 HB2 Filter 0 Table 21 and Figure 152 show the coefficients and response of the HB2 filter. –20 MAGNITUDE (dB) The third decimate-by-2, half-band, low-pass FIR filter (HB2) uses a 19-tap, symmetrical, fixed coefficient filter implementation that is optimized for low power consumption. The HB2 filter is only used when complex outputs (decimate by 4, 8, or 16) or real outputs (decimate by 2, 4, or 8) are enabled; otherwise, the filter is bypassed. –40 –60 –80 –100 Table 21. HB2 Filter Coefficients Normalized Coefficient 0.000614 0 −0.005066 0 0.022179 0 −0.073517 0 0.305786 0.500000 Decimal Coefficient (19-Bit) 161 0 −1328 0 5814 0 −19,272 0 80,160 131,072 0 MAGNITUDE (dB) –20 –40 –60 –80 –100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 NORMALIZED FREQUENCY (× π RAD/SAMPLE) 11752-047 –120 Figure 152. HB2 Filter Response HB1 Filter The fourth and final decimate-by-2, half-band, low-pass FIR filter (HB1) uses a 55-tap, symmetrical, fixed coefficient filter implementation, optimized for low power consumption. The HB1 filter is always enabled and cannot be bypassed. Table 22 and Figure 153 show the coefficients and response of the HB1 filter. –120 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 NORMALIZED FREQUENCY (× π RAD/SAMPLE) 11752-048 HB2 Coefficient Number C1, C19 C2, C18 C3, C17 C4, C16 C5, C15 C6, C14 C7, C13 C8, C12 C9, C11 C10 Figure 153. HB1 Filter Response Table 22. HB1 Filter Coefficients HB1 Coefficient Number C1, C55 C2, C54 C3, C53 C4, C52 C5, C51 C6, C50 C7, C49 C8, C48 C9, C47 C10, C46 C11, C45 C12, C44 C13, C43 C14, C42 C15, C41 C16, C40 C17, C39 C18, C38 C19, C37 C20, C36 C21, C35 C22, C34 C23, C33 C24, C32 C25, C31 C26, C30 C27, C29 C28 Rev. C | Page 59 of 97 Normalized Coefficient −0.000023 0 0.000097 0 −0.000288 0 0.000696 0 −0.0014725 0 0.002827 0 −0.005039 0 0.008491 0 −0.013717 0 0.021591 0 −0.033833 0 0.054806 0 −0.100557 0 0.316421 0.500000 Decimal Coefficient (21-Bit) −24 0 102 0 −302 0 730 0 −1544 0 2964 0 −5284 0 8903 0 −14,383 0 22,640 0 −35,476 0 57,468 0 −105,442 0 331,792 524,288 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet DDC GAIN STAGE DDC COMPLEX TO REAL CONVERSION Each DDC contains an independently controlled gain stage. The gain is selectable as either 0 dB or 6 dB. When mixing a real input signal down to baseband, it is recommended that the user enable the 6 dB of gain to recenter the dynamic range of the signal within the full scale of the output bits. Each DDC contains an independently controlled complex to real conversion block. The complex to real conversion block reuses the last filter (HB1 FIR) in the filtering stage, along with an fS/4 complex mixer to upconvert the signal. After up converting the signal, the Q portion of the complex mixer is no longer needed and is dropped. When mixing a complex input signal down to baseband, the mixer has already recentered the dynamic range of the signal within the full scale of the output bits and no additional gain is necessary. However, the optional 6 dB gain can be used to compensate for low signal strengths. The downsample by 2 portion of the HB1 FIR filter is bypassed when using the complex to real conversion stage (see Figure 154). HB1 FIR Figure 154 shows a simplified block diagram of the complex to real conversion. GAIN STAGE COMPLEX TO REAL ENABLE LOW-PASS FILTER I 2 0dB OR 6dB I 0 I/REAL 1 COMPLEX TO REAL CONVERSION 0dB OR 6dB I cos(ωt) + REAL 90° fS/4 0° – sin(ωt) LOW-PASS FILTER 2 Q 0dB OR 6dB Q Q 11752-049 Q 0dB OR 6dB HB1 FIR Figure 154. Complex to Real Conversion Block Rev. C | Page 60 of 97 Design Resources Online Documentation Product Overview Discussion Data Sheet Sample & Buy AD9680 DDC EXAMPLE CONFIGURATIONS Table 23 describes the register settings for multiple DDC example configurations. Table 23. DDC Example Configurations Chip Application Layer One DDC Chip Decimation Ratio 2 DDC Input Type Complex DDC Output Type Complex Bandwidth per DDC1 38.5% × fS No. of Virtual Converters Required 2 Two DDCs 4 Complex Complex 19.25% × fS 4 Two DDCs 4 Complex Real 9.63% × fS 2 Two DDCs 4 Real Real 9.63% × fS 2 Two DDCs 4 Real Complex 19.25% × fS 4 Rev. C | Page 61 of 97 Register Settings2 Register 0x200 = 0x01 (one DDC; I/Q selected) Register 0x201 = 0x01 (chip decimate by 2) Register 0x310 = 0x83 (complex mixer; 0 dB gain; variable IF; complex outputs; HB1 filter) Register 0x311 = 0x04 (DDC I input = ADC Channel A; DDC Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x200 = 0x02 (two DDCs; I/Q selected) Register 0x201 = 0x02 (chip decimate by 4) Register 0x310, Register 0x330 = 0x80 (complex mixer; 0 dB gain; variable IF; complex outputs; HB2 + HB1 filters) Register 0x311, Register 0x331 = 0x04 (DDC I input = ADC Channel A; DDC Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x200 = 0x22 (two DDCs; I only selected) Register 0x201 = 0x02 (chip decimate by 4) Register 0x310, Register 0x330 = 0x89 (complex mixer; 0 dB gain; variable IF; real output; HB3 + HB2 + HB1 filters) Register 0x311, Register 0x331 = 0x04 (DDC I Input = ADC Channel A; DDC Q Input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x200 = 0x22 (two DDCs; I only selected) Register 0x201 = 0x02 (chip decimate by 4) Register 0x310, Register 0x330 = 0x49 (real mixer; 6 dB gain; variable IF; real output; HB3 + HB2 + HB1 filters) Register 0x311 = 0x00 (DDC 0 I input = ADC Channel A; DDC 0 Q input = ADC Channel A) Register 0x331 = 0x05 (DDC 1 I input = ADC Channel B; DDC 1 Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x200 = 0x02 (two DDCs; I/Q selected) Register 0x201 = 0x02 (chip decimate by 4) Register 0x310, Register 0x330 = 0x40 (real mixer; 6 dB gain; variable IF; complex output; HB2 + HB1 filters) Register 0x311 = 0x00 (DDC 0 I input = ADC Channel A; DDC 0 Q input = ADC Channel A) Register 0x331 = 0x05 (DDC 1 I input = ADC Channel B; DDC 1 Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Design Resources Online Documentation Product Overview AD9680 Discussion Sample & Buy Data Sheet Chip Application Layer Two DDCs Chip Decimation Ratio 8 DDC Input Type Real DDC Output Type Real Bandwidth per DDC1 4.81% × fS No. of Virtual Converters Required 2 Four DDCs 8 Real Complex 9.63% × fS 8 Four DDCs 8 Real Real 4.81% × fS 4 Rev. C | Page 62 of 97 Register Settings2 Register 0x200 = 0x22 (two DDCs; I only selected) Register 0x201 = 0x03 (chip decimate by 8) Register 0x310, Register 0x330 = 0x4A (real mixer; 6 dB gain; variable IF; real output; HB4 + HB3 + HB2 + HB1 filters) Register 0x311 = 0x00 (DDC 0 I input = ADC Channel A; DDC 0 Q input = ADC Channel A) Register 0x331 = 0x05 (DDC 1 I input = ADC Channel B; DDC 1 Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x200 = 0x03 (four DDCs; I/Q selected) Register 0x201 = 0x03 (chip decimate by 8) Register 0x310, Register 0x330, Register 0x350, Register 0x370 = 0x41 (real mixer; 6 dB gain; variable IF; complex output; HB3+HB2+HB1 filters) Register 0x311 = 0x00 (DDC 0 I input = ADC Channel A; DDC 0 Q input = ADC Channel A) Register 0x331 = 0x00 (DDC 1 I input = ADC Channel A; DDC 1 Q input = ADC Channel A) Register 0x351 = 0x05 (DDC 2 I input = ADC Channel B; DDC 2 Q input = ADC Channel B) Register 0x371 = 0x05 (DDC 3 I input = ADC Channel B; DDC 3 Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x354, Register 0x355, Register 0x360, Register 0x361 = FTW and POW set as required by application for DDC 2 Register 0x374, Register 0x375, Register 0x380, Register 0x381 = FTW and POW set as required by application for DDC 3 Register 0x200 = 0x23 (four DDCs; I only selected) Register 0x201 = 0x03 (chip decimate by 8) Register 0x310, Register 0x330, Register 0x350, Register 0x370 = 0x4A (real mixer; 6 dB gain; variable IF; real output; HB4 + HB3 + HB2 + HB1 filters) Register 0x311 = 0x00 (DDC 0 I input = ADC Channel A; DDC 0 Q input = ADC Channel A) Register 0x331 = 0x00 (DDC 1 I input = ADC Channel A; DDC 1 Q input = ADC Channel A) Register 0x351 = 0x05 (DDC 2 I input = ADC Channel B; DDC 2 Q input = ADC Channel B) Register 0x371 = 0x05 (DDC 3 I input = ADC Channel B; DDC 3 Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x354, Register 0x355, Register 0x360, Register 0x361 = FTW and POW set as required by application for DDC 2 Register 0x374, Register 0x375, Register 0x380, Register 0x381 = FTW and POW set as required by application for DDC 3 Design Resources Online Documentation Product Overview Data Sheet Chip Application Layer Four DDCs 1 2 Chip Decimation Ratio 16 Discussion Sample & Buy AD9680 DDC Input Type Real DDC Output Type Complex Bandwidth per DDC1 4.81% × fS No. of Virtual Converters Required 8 Register Settings2 Register 0x200 = 0x03 (four DDCs; I/Q selected) Register 0x201 = 0x04 (chip decimate by 16) Register 0x310, Register 0x330, Register 0x350, Register 0x370 = 0x42 (real mixer; 6 dB gain; variable IF; complex output; HB4 + HB3 + HB2 + HB1 filters) Register 0x311 = 0x00 (DDC 0 I input = ADC Channel A; DDC 0 Q input = ADC Channel A) Register 0x331 = 0x00 (DDC 1 I input = ADC Channel A; DDC 1 Q input = ADC Channel A) Register 0x351 = 0x05 (DDC 2 I input = ADC Channel B; DDC 2 Q input = ADC Channel B) Register 0x371 = 0x05 (DDC 3 I input = ADC Channel B; DDC 3 Q input = ADC Channel B) Register 0x314, Register 0x315, Register 0x320, Register 0x321 = FTW and POW set as required by application for DDC 0 Register 0x334, Register 0x335, Register 0x340, Register 0x341 = FTW and POW set as required by application for DDC 1 Register 0x354, Register 0x355, Register 0x360, Register 0x361 = FTW and POW set as required by application for DDC 2 Register 0x374, Register 0x375, Register 0x380, Register 0x381 = FTW and POW set as required by application for DDC 3 fS is the ADC sample rate. Bandwidths listed are <−0.001 dB of pass-band ripple and >100 dB of stop-band alias rejection. The NCOs must be synchronized either through the SPI or through the SYSREF± pin after all writes to the FTW or POW registers have completed, to ensure the proper operation of the NCO. See the NCO Synchronization section for more information. Rev. C | Page 63 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet DIGITAL OUTPUTS INTRODUCTION TO THE JESD204B INTERFACE • The AD9680 digital outputs are designed to the JEDEC standard JESD204B, serial interface for data converters. JESD204B is a protocol to link the AD9680 to a digital processing device over a serial interface with lane rates of up to 12.5 Gbps. The benefits of the JESD204B interface over LVDS include a reduction in required board area for data interface routing, and an ability to enable smaller packages for converter and logic devices. JESD204B OVERVIEW • • • K is the number of frames per multiframe (AD9680 value = 4, 8, 12, 16, 20, 24, 28, or 32 ) S is the samples transmitted/single converter/frame cycle (AD9680 value = set automatically based on L, M, F, and N΄) HD is the high density mode (AD9680 = set automatically based on L, M, F, and N΄) CF is the number of control words/frame clock cycle/ converter device (AD9680 value = 0) The JESD204B data transmit block assembles the parallel data from the ADC into frames and uses 8-bit/10-bit encoding as well as optional scrambling to form serial output data. Lane synchronization is supported through the use of special control characters during the initial establishment of the link. Additional control characters are embedded in the data stream to maintain synchronization thereafter. A JESD204B receiver is required to complete the serial link. For additional details on the JESD204B interface, refer to the JESD204B standard. Figure 155 shows a simplified block diagram of the AD9680 JESD204B link. By default, the AD9680 is configured to use two converters and four lanes. Converter A data is output to SERDOUT0± and/or SERDOUT1±, and Converter B is output to SERDOUT2± and/or SERDOUT3±. The AD9680 allows other configurations such as combining the outputs of both converters onto a single lane, or changing the mapping of the A and B digital output paths. These modes are set up via a quick configuration register in the SPI register map, along with additional customizable options. The AD9680 JESD204B data transmit block maps up to two physical ADCs or up to eight virtual converters (when DDCs are enabled) over a link. A link can be configured to use one, two, or four JESD204B lanes. The JESD204B specification refers to a number of parameters to define the link, and these parameters must match between the JESD204B transmitter (the AD9680 output) and the JESD204B receiver (the logic device input). By default in the AD9680, the 14-bit converter word from each converter is broken into two octets (eight bits of data). Bit 13 (MSB) through Bit 6 are in the first octet. The second octet contains Bit 5 through Bit 0 (LSB) and two tail bits. The tail bits can be configured as zeros or a pseudorandom number sequence. The tail bits can also be replaced with control bits indicating overrange, SYSREF±, or fast detect output. The JESD204B link is described according to the following parameters: The two resulting octets can be scrambled. Scrambling is optional; however, it is recommended to avoid spectral peaks when transmitting similar digital data patterns. The scrambler uses a self-synchronizing, polynomial-based algorithm defined by the equation 1 + x14 + x15. The descrambler in the receiver is a self-synchronizing version of the scrambler polynomial. • • • • • L is the number of lanes/converter device (lanes/link) (AD9680 value = 1, 2, or 4) M is the number of converters/converter device (virtual converters/link) (AD9680 value = 1, 2, 4, or 8) F is the octets/frame (AD9680 value = 1, 2, 4, 8, or 16) N΄ is the number of bits per sample (JESD204B word size) (AD9680 value = 8 or 16) N is the converter resolution (AD9680 value = 7 to 16) CS is the number of control bits/sample (AD9680 value = 0, 1, 2, or 3) The two octets are then encoded with an 8-bit/10-bit encoder. The 8-bit/10-bit encoder works by taking eight bits of data (an octet) and encoding them into a 10-bit symbol. Figure 156 shows how the 14-bit data is taken from the ADC, how the tail bits are added, how the two octets are scrambled, and how the octets are encoded into two 10-bit symbols. Figure 156 illustrates the default data format. CONVERTER 0 CONVERTER A INPUT ADC A MUX/ FORMAT (SPI REG 0x561, REG 0x564) CONVERTER B INPUT JESD204B LINK CONTROL (L.M.F) (SPI REG 0x570) ADC B LANE MUX AND MAPPING (SPI REG 0x5B0, REG 0x5B2, REG 0x5B3, REG 0x5B5, REG 0x5B6) SERDOUT0–, SERDOUT0+ SERDOUT1–, SERDOUT1+ SERDOUT2–, SERDOUT2+ SERDOUT3–, SERDOUT3+ CONVERTER 1 11752-050 • SYSREF± SYNCINB± Figure 155. Transmit Link Simplified Block Diagram Showing Full Bandwidth Mode (Register 0x200 = 0x00) Rev. C | Page 64 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 JESD204B INTERFACE TEST PATTERN (REG 0x573, REG 0x551 TO REG 0x558) JESD204B LONG TRANSPORT TEST PATTERN REG 0x571[5] SERIALIZER MSB A13 A12 A11 A10 A9 A8 A7 LSB A6 A5 A4 A3 A2 A1 A0 C2 T MSB S7 S6 S5 S4 S3 S2 S1 LSB S0 S7 S6 S5 S4 S3 S2 S1 S0 8-BIT/10-BIT ENCODER a b a b c d e f g h i j SERDOUT0± SERDOUT1± i j a b SYMBOL0 i j SYMBOL1 a b c d e f g h i j 11752-051 TAIL BITS 0x571[6] SCRAMBLER 1 + x14 + x15 (OPTIONAL) OCTET 1 JESD204B SAMPLE CONSTRUCTION MSB A13 A12 A11 A10 A9 A8 A7 A6 A5 A4 A3 A2 A1 LSB A0 OCTET 1 OCTET 0 FRAME CONSTRUCTION OCTET 0 ADC TEST PATTERNS (RE0x550, REG 0x551 TO REG 0x558) ADC JESD204B DATA LINK LAYER TEST PATTERNS REG 0x574[2:0] C2 CONTROL BITS C1 C0 Figure 156. ADC Output Data Path Showing Data Framing TRANSPORT LAYER SAMPLE CONSTRUCTION FRAME CONSTRUCTION SCRAMBLER ALIGNMENT CHARACTER GENERATION 8-BIT/10-BIT ENCODER CROSSBAR MUX SERIALIZER Tx OUTPUT 11752-052 PROCESSED SAMPLES FROM ADC PHYSICAL LAYER DATA LINK LAYER SYSREF± SYNCINB± Figure 157. Data Flow FUNCTIONAL OVERVIEW Physical Layer The block diagram in Figure 157 shows the flow of data through the JESD204B hardware from the sample input to the physical output. The processing can be divided into layers that are derived from the open source initiative (OSI) model widely used to describe the abstraction layers of communications systems. These layers are the transport layer, data link layer, and physical layer (serializer and output driver). The physical layer consists of the high speed circuitry clocked at the serial clock rate. In this layer, parallel data is converted into one, two, or four lanes of high speed differential serial data. Transport Layer The transport layer handles packing the data (consisting of samples and optional control bits) into JESD204B frames that are mapped to 8-bit octets. These octets are sent to the data link layer. The transport layer mapping is controlled by rules derived from the link parameters. Tail bits are added to fill gaps where required. The following equation can be used to determine the number of tail bits within a sample (JESD204B word): T = N΄ – N – CS Data Link Layer The data link layer is responsible for the low level functions of passing data across the link. These include optionally scrambling the data, inserting control characters for multichip synchronization/lane alignment/monitoring, and encoding 8-bit octets into 10-bit symbols. The data link layer is also responsible for sending the initial lane alignment sequence (ILAS), which contains the link configuration data used by the receiver to verify the settings in the transport layer. JESD204B LINK ESTABLISHMENT The AD9680 JESD204B transmitter (Tx) interface operates in Subclass 1 as defined in the JEDEC Standard 204B (July 2011 specification). The link establishment process is divided into the following steps: code group synchronization and SYNCINB±, initial lane alignment sequence, and user data and error correction. Code Group Synchronization (CGS) and SYNCINB± The CGS is the process by which the JESD204B receiver finds the boundaries between the 10-bit symbols in the stream of data. During the CGS phase, the JESD204B transmit block transmits /K28.5/ characters. The receiver must locate /K28.5/ characters in its input data stream using clock and data recovery (CDR) techniques. The receiver issues a synchronization request by asserting the SYNCINB± pin of the AD9680 low. The JESD204B Tx then begins sending /K/ characters. Once the receiver has synchronized, it waits for the correct reception of at least four consecutive /K/ symbols. It then deasserts SYNCINB±. The AD9680 then transmits an ILAS on the following local multiframe clock (LMFC) boundary. For more information on the code group synchronization phase, refer to the JEDEC Standard JESD204B, July 2011, Section 5.3.3.1. Rev. C | Page 65 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet User Data and Error Detection The SYNCINB± pin operation can also be controlled by the SPI. The SYNCINB± signal is a differential dc-coupled LVDS mode signal by default, but it can also be driven single-ended. For more information on configuring the SYNCINB± pin operation, refer to Register 0x572. After the initial lane alignment sequence is complete, the user data is sent. Normally, within a frame, all characters are considered user data. However, to monitor the frame clock and multiframe clock synchronization, there is a mechanism for replacing characters with /F/ or /A/ alignment characters when the data meets certain conditions. These conditions are different for unscrambled and scrambled data. The scrambling operation is enabled by default, but it can be disabled using the SPI. The SYNCINB± pins can also be configured to run in CMOS (single-ended) mode, by setting Bit[4] in Register 0x572. When running SYNCINB± in CMOS mode, connect the CMOS SYNCINB signal to Pin 21 (SYNCINB+) and leave Pin 20 (SYNCINB−) floating. For scrambled data, any 0xFC character at the end of a frame is replaced by an /F/, and any 0x7C character at the end of a multiframe is replaced with an /A/. The JESD204B receiver (Rx) checks for /F/ and /A/ characters in the received data stream and verifies that they only occur in the expected locations. If an unexpected /F/ or /A/ character is found, the receiver handles the situation by using dynamic realignment or asserting the SYNCINB± signal for more than four frames to initiate a resynchronization. For unscrambled data, if the final character of two subsequent frames is equal, the second character is replaced with an /F/ if it is at the end of a frame, and an /A/ if it is at the end of a multiframe. Initial Lane Alignment Sequence (ILAS) The ILAS phase follows the CGS phase and begins on the next LMFC boundary. The ILAS consists of four multiframes, with an /R/ character marking the beginning and an /A/ character marking the end. The ILAS begins by sending an /R/ character followed by 0 to 255 ramp data for one multiframe. On the second multiframe, the link configuration data is sent, starting with the third character. The second character is a /Q/ character to confirm that the link configuration data will follow. All undefined data slots are filled with ramp data. The ILAS sequence is never scrambled. Insertion of alignment characters can be modified using SPI. The frame alignment character insertion (FACI) is enabled by default. More information on the link controls is available in the Memory Map section, Register 0x571. The ILAS sequence construction is shown in Figure 158. The four multiframes include the following: • • • Multiframe 1. Begins with an /R/ character (/K28.0/) and ends with an /A/ character (/K28.3/). Multiframe 2. Begins with an /R/ character followed by a /Q/ character (/K28.4/), followed by link configuration parameters over 14 configuration octets (see Table 24) and ends with an /A/ character. Many of the parameter values are of the value – 1 notation. Multiframe 3. Begins with an /R/ character (/K28.0/) and ends with an /A/ character (/K28.3/). Multiframe 4. Begins with an /R/ character (/K28.0/) and ends with an /A/ character (/K28.3/). K K R D D A R Q C C D D A 8-Bit/10-Bit Encoder The 8-bit/10-bit encoder converts 8-bit octets into 10-bit symbols and inserts control characters into the stream when needed. The control characters used in JESD204B are shown in Table 24. The 8-bit/10-bit encoding ensures that the signal is dc balanced by using the same number of ones and zeros across multiple symbols. The 8-bit/10-bit interface has options that can be controlled via the SPI. These operations include bypass and invert. These options are troubleshooting tools for the verification of the digital front end (DFE). See the Memory Map section, Register 0x572[2:1] for information on configuring the 8-bit/10-bit encoder. R D D A R D D A D END OF MULTIFRAME START OF ILAS START OF LINK CONFIGURATION DATA START OF USER DATA Figure 158. Initial Lane Alignment Sequence Rev. C | Page 66 of 97 11752-053 • Design Resources Online Documentation Product Overview Discussion Data Sheet Sample & Buy AD9680 Table 24. AD9680 Control Characters used in JESD204B Abbreviation /R/ /A/ /Q/ /K/ /F/ 1 Control Symbol /K28.0/ /K28.3/ /K28.4/ /K28.5/ /K28.7/ 10-Bit Value, RD1 = −1 001111 0100 001111 0011 001111 0100 001111 1010 001111 1000 8-Bit Value 000 11100 011 11100 100 11100 101 11100 111 11100 10-Bit Value, RD1 = +1 110000 1011 110000 1100 110000 1101 110000 0101 110000 0111 Description Start of multiframe Lane alignment Start of link configuration data Group synchronization Frame alignment RD means running disparity. PHYSICAL LAYER (DRIVER) OUTPUTS If there is no far-end receiver termination, or if there is poor differential trace routing, timing errors can result. To avoid such timing errors, it is recommended that the trace length be less than six inches, and that the differential output traces be close together and at equal lengths. Digital Outputs, Timing, and Controls The AD9680 physical layer consists of drivers that are defined in the JEDEC Standard JESD204B, July 2011. The differential digital outputs are powered up by default. The drivers use a dynamic 100 Ω internal termination to reduce unwanted reflections. Figure 161 to Figure 166 show an example of the digital output data eye, time interval error (TIE) jitter histogram, and bathtub curve for one AD9680 lane running at 10 Gbps and 6 Gbps, respectively. The format of the output data is twos complement by default. To change the output data format, see the Memory Map section (Register 0x561 in Table 36). Place a 100 Ω differential termination resistor at each receiver input to result in a nominal 300 mV p-p swing at the receiver (see Figure 159). Alternatively, single-ended 50 Ω termination can be used. When single-ended termination is used, the termination voltage is DRVDD/2. Otherwise, 0.1 µF ac coupling capacitors can be used to terminate to any single-ended voltage. De-Emphasis VRXCM DRVDD 0.1µF 100Ω DIFFERENTIAL TRACE PAIR 50Ω 50Ω SERDOUTx+ 100Ω OR RECEIVER SERDOUTx– OUTPUT SWING = 300mV p-p 11752-054 0.1µF VCM = VRXCM Figure 159. AC-Coupled Digital Output Termination Example The AD9680 digital outputs can interface with custom ASICs and FPGA receivers, providing superior switching performance in noisy environments. Single point-to-point network topologies are recommended with a single differential 100 Ω termination resistor placed as close to the receiver inputs as possible. The common mode of the digital output automatically biases itself to half the DRVDD supply of 1.2 V (VCM = 0.6 V). See Figure 160 for dc coupling the outputs to the receiver logic. DRVDD De-emphasis enables the receiver eye diagram mask to be met in conditions where the interconnect insertion loss does not meet the JESD204B specification. Use the de-emphasis feature only when the receiver is unable to recover the clock due to excessive insertion loss. Under normal conditions, it is disabled to conserve power. Additionally, enabling and setting too high a de-emphasis value on a short link can cause the receiver eye diagram to fail. Use the de-emphasis setting with caution because it can increase electromagnetic interference (EMI). See the Memory Map section (Register 0x5C1 to Register 0x5C5 in Table 36) for more details. Phase-Locked Loop The phase-locked loop (PLL) is used to generate the serializer clock, which operates at the JESD204B lane rate. The status of the PLL lock can be checked in the PLL locked status bit (Register 0x56F, Bit 7). This read only bit lets the user know if the PLL has achieved a lock for the specific setup. The JESD204B lane rate control, Bit 4 of Register 0x56E, must be set to correspond with the lane rate. 100Ω DIFFERENTIAL TRACE PAIR SERDOUTx+ 100Ω RECEIVER OUTPUT SWING = 300mV p-p VCM = DRVDD/2 11752-055 SERDOUTx– Figure 160. DC-Coupled Digital Output Termination Example Rev. C | Page 67 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet 400 400 300 300 200 VOLTAGE (mV) VOLTAGE (mV) 200 100 0 Tx EYE MASK –100 100 0 Tx EYE MASK –100 –200 –200 –300 –300 –400 –80 –60 –40 –20 0 20 40 60 80 TIME (ps) –150 –100 –50 0 50 100 150 TIME (ps) Figure 161. Digital Outputs Data Eye, External 100 Ω Terminations at 10 Gbps 11752-503 –100 11752-500 –400 Figure 164. Digital Outputs Data Eye, External 100 Ω Terminations at 6 Gbps 8000 12000 7000 10000 6000 4000 HITS HITS 8000 6000 4000 3000 4000 2000 2000 –2 0 2 4 6 TIME (ps) Figure 162. Digital Outputs Histogram, External 100 Ω Terminations at 10 Gbps 1–2 1–2 1–4 1–4 1–6 1–6 BER 1 1–10 1–12 1–12 1–14 1–14 –0.4 –0.3 –0.2 –0.1 0 UI 0.1 0.2 0.3 0.4 0.5 Figure 163. Digital Outputs Bathtub Curve, External 100 Ω Terminations at 10 Gbps –1 1 0 2 3 4 1–8 1–10 1–16 –0.5 –2 Figure 165. Digital Outputs Histogram, External 100 Ω Terminations at 6 Gbps 1 1–8 –3 TIME (ps) 1–16 –0.5 11752-502 BER 0 –4 –0.4 –0.3 –0.2 –0.1 0 UI 0.1 0.2 0.3 0.4 0.5 11752-505 –4 11752-501 0 11752-504 1000 Figure 166. Digital Outputs Bathtub Curve, External 100 Ω Terminations at 6 Gbps Rev. C | Page 68 of 97 Online Documentation Product Overview Design Resources Sample & Buy Discussion Data Sheet AD9680 Figure 167 shows a block diagram of the two scenarios described for I/Q transport layer mapping. JESD204B TX CONVERTER MAPPING To support the different chip operating modes, the AD9680 design treats each sample stream (real or I/Q) as originating from separate virtual converters. The I/Q samples are always mapped in pairs with the I samples mapped to the first virtual converter and the Q samples mapped to the second virtual converter. With this transport layer mapping, the number of virtual converters are the same whether DIGITAL DOWNCONVERSION M=2 I CONVERTER 0 REAL ADC REAL DIGITAL DOWN CONVERSION JESD204B Tx L LANES JESD204B Tx L LANES Q CONVERTER 1 I/Q ANALOG MIXING M=2 I REAL Σ ADC I CONVERTER 0 90° PHASE Q ADC Q CONVERTER 1 Figure 167. I/Q Transport Layer Mapping REAL/I ADC A SAMPLING AT fS REAL/I REAL/Q REAL/I REAL/Q I/Q CROSSBAR MUX REAL/I REAL/Q REAL/Q ADC B SAMPLING AT fS REAL/I REAL/Q DDC 0 I I Q Q DDC 1 I I Q Q DDC 2 I I Q Q DDC 3 I I Q Q REAL/I CONVERTER 0 Q CONVERTER 1 REAL/I CONVERTER 2 Q CONVERTER 3 REAL/I CONVERTER 4 Q CONVERTER 5 REAL/I CONVERTER 6 Q CONVERTER 7 Figure 168. DDCs and Virtual Converter Mapping Rev. C | Page 69 of 97 OUTPUT INTERFACE 11752-059 A single real converter is used along with a digital downconverter block producing I/Q outputs, or An analog downconversion is used with two real converters producing I/Q outputs. 11752-058 The JESD204B Tx block for AD9680 supports up to four DDC blocks. Each DDC block outputs either two sample streams (I/Q) for the complex data components (real + imaginary), or one sample stream for real (I) data. The JESD204B interface can be configured to use up to eight virtual converters depending on the DDC configuration. Figure 168 shows the virtual converters and their relationship to the DDC outputs when complex outputs are used. Table 25 shows the virtual converter mapping for each chip operating mode when channel swapping is disabled. Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Data Sheet Table 25. Virtual Converter Mapping Number of Virtual Converters Supported 1 to 2 Chip Operating Mode (0x200, Bits[1:0]) Full bandwidth mode (0x0) 1 One DDC mode (0x1) One DDC mode (0x1) Two DDC mode (0x2) Two DDC mode (0x2) Four DDC mode (0x3) Four DDC mode (0x3) 2 2 4 4 8 Chip Q Ignore (0x200, Bit 5) Real or complex (0x0) Real (I only) (0x1) Virtual Converter Mapping 0 ADC A samples 1 ADC B samples 2 Unused 3 Unused 4 Unused 5 Unused 6 Unused 7 Unused DDC 0 I samples Unused Unused Unused Unused Unused Unused Unused Complex (I/Q) (0x0) DDC 0 I samples DDC 0 Q samples Unused Unused Unused Unused Unused Unused Real (I only) (0x1) DDC 0 I samples DDC 1 I samples Unused Unused Unused Unused Unused Unused Complex (I/Q) (0x0) DDC 0 I samples DDC 0 Q samples DDC 1 I samples DDC 1 Q samples Unused Unused Unused Unused Real (I only) (0x1) DDC 0 I samples DDC 1 I samples DDC 2 I samples DDC 3 I samples Unused Unused Unused Unused Complex (I/Q) (0x0) DDC 0 I samples DDC 0 Q samples DDC 1 I samples DDC 1 Q samples DDC 2 I samples DDC 2 Q samples DDC 3 I samples DDC 3 Q samples Rev. C | Page 70 of 97 Product Overview Design Resources Online Documentation Sample & Buy Discussion Data Sheet AD9680 CONFIGURING THE JESD204B LINK The decimation ratio (DCM) is the parameter programmed in Register 0x201. The AD9680 has one JESD204B link. The device offers an easy way to set up the JESD204B link through the JESD04B quick configuration register (Register 0x570). The serial outputs (SERDOUT0± to SERDOUT3±) are considered to be part of one JESD204B link. The basic parameters that determine the link setup are • • • The following steps can be used to configure the output: 1. 2. 3. 4. 5. 6. Number of lanes per link (L) Number of converters per link (M) Number of octets per frame (F) If the lane line rate calculated is less than 6.25 Gbps, select the low line rate option by programming a value of 0x10 to Register 0x56E. If the internal DDCs are used for on-chip digital processing, M represents the number of virtual converters. The virtual converter mapping setup is shown in Figure 168. Table 26 and Table 27 show the JESD204B output configurations supported for both N΄ = 16 and N΄ = 8 for a given number of virtual converters. Take care to ensure that the serial line rate for a given configuration is within the supported range of 3.125 Gbps to 12.5 Gbps. The maximum lane rate allowed by the JESD204B specification is 12.5 Gbps. The lane line rate is related to the JESD204B parameters using the following equation: 10 M × N '× × f OUT 8 Lane Line Rate = L where f OUT = Power down the link. Select quick configuration options. Configure detailed options. Set output lane mapping (optional). Set additional driver configuration options (optional). Power up the link. f ADC _ CLOCK Decimation Ratio Table 26. JESD204B Output Configurations for N΄ = 16 Number of Virtual Converters Supported (Same Value as M) 1 2 4 8 JESD204B Quick Configuration (0x570) 0x01 0x40 0x41 0x80 0x81 0x0A 0x49 0x88 0x89 0x13 0x52 0x91 0x1C 0x5B 0x9A JESD204B Transport Layer Settings2 JESD204B Serial Line Rate1 20 × fOUT 10 × fOUT 10 × fOUT 5 × fOUT 5 × fOUT 40 × fOUT 20 × fOUT 10 × fOUT 10 × fOUT 80 × fOUT 40 × fOUT 20 × fOUT 160 × fOUT 80 × fOUT 40 × fOUT L 1 2 2 4 4 1 2 4 4 1 2 4 1 2 4 M 1 1 1 1 1 2 2 2 2 4 4 4 8 8 8 F 2 1 2 1 2 4 2 1 2 8 4 2 16 8 4 S 1 1 2 2 4 1 1 1 2 1 1 1 1 1 1 HD 0 1 0 1 0 0 0 1 0 0 0 0 0 0 0 N 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 8 to 16 N΄ 16 16 16 16 16 16 16 16 16 16 16 16 16 16 16 CS 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 0 to 3 K3 Only valid K values that are divisible by 4 are supported fOUT = output sample rate = ADC sample rate/chip decimation ratio. The JESD204B serial line rate must be ≥3125 Mbps and ≤12,500 Mbps; when the serial line rate is ≤12.5 Gbps and ≥ 6.25 Gbps, the low line rate mode must be disabled (set Bit 4 to 0x0 in 0x56E). When the serial line rate is <6.25 Gbps and ≥3.125 Gbps, the low line rate mode must be enabled (set Bit 4 to 0x1 in 0x56E). 2 JESD204B transport layer descriptions are as described in the JESD204B Overview section. 3 For F = 1, K = 20, 24, 28, and 32. For F = 2, K = 12, 16, 20, 24, 28, and 32. For F = 4, K = 8, 12, 16, 20, 24, 28, and 32. For F = 8 and F = 16, K = 4, 8, 12, 16, 20, 24, 28, and 32. 1 Rev. C | Page 71 of 97 Product Overview Design Resources Online Documentation Sample & Buy Discussion AD9680 Data Sheet Table 27. JESD204B Output Configurations for N΄ = 8 Number of Virtual Converters Supported (Same Value as M) 1 2 JESD204B Quick Configuration (0x570) 0x00 0x01 0x40 0x41 0x42 0x80 0x81 0x09 0x48 0x49 0x88 0x89 0x8A JESD204B Transport Layer Settings2 Serial Line Rate1 10 × fOUT 10 × fOUT 5 × fOUT 5 × fOUT 5 × fOUT 2.5 × fOUT 2.5 × fOUT 20 × fOUT 10 × fOUT 10 × fOUT 5 × fOUT 5 × fOUT 5 × fOUT L 1 1 2 2 2 4 4 1 2 2 4 4 4 M 1 1 1 1 1 1 1 2 2 2 2 2 2 F 1 2 1 2 4 1 2 2 1 2 1 2 4 S 1 2 2 4 8 4 8 1 1 2 2 4 8 HD 0 0 0 0 0 0 0 0 0 0 0 0 0 N 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 7 to 8 N΄ 8 8 8 8 8 8 8 8 8 8 8 8 8 CS 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 0 to 1 K3 Only valid K values which are divisible by 4 are supported fOUT = output sample rate = ADC sample rate/chip decimation ratio. The JESD204B serial line rate must be ≥3125 Mbps and ≤12,500 Mbps; when the serial line rate is ≤12.5 Gbps and ≥6.25 Gbps, the low line rate mode must be disabled (set Bit 4 to 0x0 in Register 0x56E). When the serial line rate is <6.25 Gbps and ≥3.125 Gbps, the low line rate mode must be enabled (set Bit 4 to 0x1 in Register 0x56E). 2 JESD204B transport layer descriptions are as described in the JESD204B Overview section. 3 For F = 1, K = 20, 24, 28, and 32. For F = 2, K = 12, 16, 20, 24, 28, and 32. For F = 4, K = 8, 12, 16, 20, 24, 28, and 32. For F = 8 and F = 16, K = 4, 8, 12, 16, 20, 24, 28, and 32. 1 See the Example 1: Full Bandwidth Mode section and the Example 2: ADC with DDC Option (Two ADCs Plus Four DDCs) section for two examples describing which JESD204B transport layer settings are valid for a given chip mode. CMOS FAST DETECTION REAL/I Example 1: Full Bandwidth Mode 14-BIT AT 1Gbps CONVERTER 0 JESD204B TRANSMIT INTERFACE Chip application mode = full bandwidth mode (see Figure 169). Two 14-bit converters at 1000 MSPS Full bandwidth application layer mode No decimation REAL/Q 14-BIT AT 1Gbps CONVERTER 1 FAST DETECTION JESD204B output configuration is as follows: • • CMOS Two virtual converters required (see Table 26) Output sample rate (fOUT) = 1000/1 = 1000 MSPS Figure 169. Full Bandwidth Mode Example 2: ADC with DDC Option (Two ADCs Plus Four DDCs) JESD204B supported output configurations (see Table 26) include: • • • • • • 11752-060 • • • L JESD204B LANES AT UP TO 12.5Gbps N΄ = 16 bits N = 14 bits L = 4, M = 2, and F = 1, or L = 4, M = 2, and F = 2 (quick configuration = 0x88 or 0x89) CS = 0 to 2 K = 32 Output serial line rate = 10 Gbps per lane, low line rate mode disabled Chip application mode = four-DDC mode. (see Figure 170). • • • • Two 14-bit converters at 1 GSPS Four DDC application layer mode with complex outputs (I/Q) Chip decimation ratio = 16 DDC decimation ratio = 16 (see Table 15). JESD204B output configuration is as follows: • • Rev. C | Page 72 of 97 Virtual converters required = 8 (see Table 26) Output sample rate (fOUT) = 1000/16 = 62.5 MSPS Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 For L = 1, low line rate mode is disabled. For L = 2, low line rate mode is enabled. JESD204B supported output configurations (see Table 26): • • • N΄ = 16 bits N = 14 bits L = 1, M = 8, and F = 16, or L = 2, M = 8, and F = 8 (quick configuration = 0x1C or 0x5B) CS = 0 to 1 K = 32 Output serial line rate = 10 Gbps per lane (L = 1) or 5 Gbps per lane (L = 2) REAL ADC A SAMPLING AT fS REAL/I REAL/Q Example 2 shows the flexibility in the digital and lane configurations for the AD9680. The sample rate is 1 GSPS; however, the outputs are all combined in either one or two lanes, depending on the I/O speed capability of the receiving device. DDC 0 I CONVERTER 0 Q CONVERTER 1 DDC 1 I CONVERTER 2 Q CONVERTER 3 DDC 2 I CONVERTER 4 Q CONVERTER 5 DDC 3 I CONVERTER 6 Q CONVERTER 7 I/Q CROSSBAR MUX REAL/I REAL SYSREF ADC B SAMPLING AT fS REAL/Q L JESD204B LANES UP TO 12.5Gbps L JESD204B LANES AT UP TO 12.5Gbps 11752-061 • • • SYNCHRONIZATION CONTROL CIRCUITS Figure 170. Two ADC Plus Four DDC Mode Rev. C | Page 73 of 97 Product Overview Design Resources Online Documentation AD9680 Discussion Sample & Buy Data Sheet MULTICHIP SYNCHRONIZATION The AD9680 has a SYSREF± input that provides flexible options for synchronizing the internal blocks. The SYSREF± input is a source synchronous system reference signal that enables multichip synchronization. The input clock divider, DDCs, signal monitor block, and JESD204B link can be synchronized using the SYSREF± input. For the highest level of timing accuracy, SYSREF± must meet setup and hold requirements relative to the CLK± input. The flowchart in Figure 171 describes the internal mechanism for multichip synchronization in the AD9680. The AD9680 supports several features that aid users in meeting the requirements set out for capturing a SYSREF± signal. The SYSREF sample event can be defined as either a synchronous low to high transition, or a synchronous high to low transition. Additionally, the AD9680 allows the SYSREF signal to be sampled using either the rising edge or falling edge of the CLK± input. The AD9680 also has the ability to ignore a programmable number (up to 16) of SYSREF± events. The SYSREF± control options can be selected using Register 0x120 and Register 0x121. Rev. C | Page 74 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 START INCREMENT SYSREF± IGNORE COUNTER NO NO RESET SYSREF± IGNORE COUNTER SYSREF± ENABLED? (0x120) NO NO SYSREF± ASSERTED? YES UPDATE SETUP/HOLD DETECTOR STATUS (0x128) YES SYSREF± IGNORE COUNTER EXPIRED? (0x121) YES ALIGN CLOCK DIVIDER PHASE TO SYSREF INPUT CLOCK DIVIDER ALIGNMENT REQUIRED? YES YES NO SYNCHRONIZATION MODE? (0x1FF) CLOCK DIVIDER AUTO ADJUST ENABLED? (0x10D) NO TIMESTAMP MODE SYSREF± TIMESTAMP DELAY (0x123) INCREMENT SYSREF± COUNTER (0x12A) CLOCK DIVIDER > 1? (0x10B) YES NO SYSREF± CONTROL BITS? (0x559, 0x55A, 0x58F) YES SYSREF± INSERTED IN JESD204B CONTROL BITS NO RAMP TEST MODE ENABLED? (0x550) NORMAL MODE YES SYSREF± RESETS RAMP TEST MODE GENERATOR BACK TO START NO YES ALIGN PHASE OF ALL INTERNAL CLOCKS (INCLUDING LMFC) TO SYSREF± SEND INVALID 8-BIT/10-BIT CHARACTERS (ALL 0's) SYNC~ ASSERTED NO SEND K28.5 CHARACTERS NORMAL JESD204B INITIALIZATION NO NO SIGNAL MONITOR ALIGNMENT ENABLED? (0x26F) YES YES ALIGN SIGNAL MONITOR COUNTERS DDC NCO ALIGNMENT ENABLED? (0x300) YES NO Figure 171. Multichip Synchronization Rev. C | Page 75 of 97 ALIGN DDC NCO PHASE ACCUMULATOR BACK TO START 11752-112 JESD204B LMFC ALIGNMENT REQUIRED? Design Resources Online Documentation Product Overview Discussion AD9680 Sample & Buy Data Sheet SYSREF± SETUP/HOLD WINDOW MONITOR To ensure a valid SYSREF signal capture, the AD9680 has a SYSREF± setup/hold window monitor. This feature allows the system designer to determine the location of the SYSREF± signals relative to the CLK± signals by reading back the amount of setup/hold margin on the interface through the memory map. Figure 172 and Figure 173 show the setup and hold status values for different phases of SYSREF±. The setup detector returns the status of the SYSREF± signal before the CLK± edge, and the hold detector returns the status of the SYSREF signal after the CLK± edge. Register 0x128 stores the status of SYSREF± and lets the user know if the SYSREF± signal is captured by the ADC. 0xF 0xE 0xD 0xC 0xB 0xA 0x9 REG 0x128[3:0] 0x8 0x7 0x6 0x5 0x4 0x3 0x2 0x1 0x0 CLK± INPUT SYSREF± INPUT VALID FLIP-FLOP HOLD (MIN) FLIP-FLOP HOLD (MIN) Figure 172. SYSREF± Setup Detector Rev. C | Page 76 of 97 11752-113 FLIP-FLOP SETUP (MIN) Online Documentation Product Overview Design Resources Discussion Data Sheet Sample & Buy AD9680 REG 0x128[7:4] 0xF 0xE 0xD 0xC 0xB 0xA 0x9 0x8 0x7 0x6 0x5 0x4 0x3 0x2 0x1 0x0 CLK± INPUT SYSREF± INPUT FLIP-FLOP SETUP (MIN) FLIP-FLOP HOLD (MIN) FLIP-FLOP HOLD (MIN) 11752-114 VALID Figure 173. SYSREF± Hold Detector Table 28 shows the description of the contents of Register 0x128 and how to interpret them. Table 28. SYSREF± Setup/Hold Monitor, Register 0x128 Register 0x128[7:4] Hold Status 0x0 0x0 to 0x8 0x8 0x8 0x9 to 0xF 0x0 Register 0x128[3:0] Setup Status 0x0 to 0x7 0x8 0x9 to 0xF 0x0 0x0 0x0 Description Possible setup error. The smaller this number, the smaller the setup margin. No setup or hold error (best hold margin). No setup or hold error (best setup and hold margin). No setup or hold error (best setup margin). Possible hold error. The larger this number, the smaller the hold margin. Possible setup or hold error. Rev. C | Page 77 of 97 Product Overview Design Resources Online Documentation AD9680 Discussion Sample & Buy Data Sheet TEST MODES ADC TEST MODES The AD9680 has various test options that aid in the system level implementation. The AD9680 has ADC test modes that are available in Register 0x550. These test modes are described in Table 29. When an output test mode is enabled, the analog section of the ADC is disconnected from the digital back-end blocks, and the test pattern is run through the output formatting block. Some of the test patterns are subject to output formatting, and some are not. The PN generators from the PN sequence tests can be reset by setting Bit 4 or Bit 5 of Register 0x550. These tests can be performed with or without an analog signal (if present, the analog signal is ignored); however, they do require an encode clock. If the application mode is set to select a DDC mode of operation, the test modes must be enabled for each DDC enabled. The test patterns can be enabled via Bit 2 and Bit 0 of Register 0x327, Register 0x347, and Register 0x367, depending on which DDC(s) are selected. The (I) data uses the test patterns selected for Channel A, and the (Q) data uses the test patterns selected for Channel B. For DDC3 only, the (I) data uses the test patterns from Channel A, and the (Q) data does not output test patterns. Bit 0 of Register 0x387 selects the Channel A test patterns to be used for the (I) data. For more information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. Table 29. ADC Test Modes1 Output Test Mode Bit Sequence 0000 0001 0010 0011 0100 0101 0110 0111 1000 Pattern Name Off (default) Midscale short +Full-scale short −Full-scale short Checkerboard PN sequence long PN sequence short One-/zero-word toggle User input Expression N/A 00 0000 0000 0000 01 1111 1111 1111 10 0000 0000 0000 10 1010 1010 1010 X23 + X18 + 1 X9 + X5 + 1 11 1111 1111 1111 Register 0x551 to Register 0x558 1111 Ramp Output (X) % 214 1 Default/ Seed Value N/A N/A N/A N/A N/A 0x3AFF 0x0092 N/A N/A N/A N/A means not applicable. Rev. C | Page 78 of 97 Sample (N, N + 1, N + 2, …) N/A N/A N/A N/A 0x1555, 0x2AAA, 0x1555, 0x2AAA, 0x1555 0x3FD7, 0x0002, 0x26E0, 0x0A3D, 0x1CA6 0x125B, 0x3C9A, 0x2660, 0x0c65, 0x0697 0x0000, 0x3FFF, 0x0000, 0x3FFF, 0x0000 User Pattern 1[15:2], User Pattern 2[15:2], User Pattern 3[15:2], User Pattern 4[15:2], User Pattern 1[15:2] … for repeat mode User Pattern 1[15:2], User Pattern 2[15:2], User Pattern 3[15:2], User Pattern 4[15:2], 0x0000 … for single mode (X) % 214, (X +1) % 214, (X +2) % 214, (X +3) % 214 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet AD9680 JESD204B BLOCK TEST MODES In addition to the ADC pipeline test modes, the AD9680 also has flexible test modes in the JESD204B block. These test modes are listed in Register 0x573 and Register 0x574. These test patterns can be injected at various points along the output data path. These test injection points are shown in Figure 156. Table 30 describes the various test modes available in the JESD204B block. For the AD9680, a transition from test modes (Register 0x573 ≠ 0x00) to normal mode (Register 0x573 = 0x00) requires an SPI soft reset. This is done by writing 0x81 to Register 0x00 (self cleared). Transport Layer Sample Test Mode The transport layer samples are implemented in the AD9680 as defined by Section 5.1.6.3 in the JEDEC JESD204B Specification. These tests are shown in Register 0x571[5]. The test pattern is equivalent to the raw samples from the ADC. Interface Test Modes The interface test modes are described in Register 0x573, Bits[3:0]. These test modes are also explained in Table 30. The interface tests can be injected at various points along the data. See Figure 156 for more information on the test injection points. Register 0x573, Bits[5:4] show where these tests are injected. Table 31, Table 32, and Table 33 show examples of some of the test modes when injected at the JESD sample input, PHY 10-bit input, and scrambler 8-bit input. UP in the tables represent the user pattern control bits from the customer register map. Table 30. JESD204B Interface Test Modes Output Test Mode Bit Sequence 0000 0001 0010 0011 0100 0101 0110 0111 1000 1110 1111 Pattern Name Off (default) Alternating checker board 1/0 word toggle 31-bit PN sequence 23-bit PN sequence 15-bit PN sequence 9-bit PN sequence 7-bit PN sequence Ramp output Continuous/repeat user test Single user test Expression Not applicable 0x5555, 0xAAAA, 0x5555, … 0x0000, 0xFFFF, 0x0000, … X31 + X28 + 1 X23 + X18 + 1 X15 + X14 + 1 X9 + X5 + 1 X7 + X6 + 1 (X) % 216 Register 0x551 to Register 0x558 Register 0x551 to Register 0x558 Default Not applicable Not applicable Not applicable 0x0003AFFF 0x003AFF 0x03AF 0x092 0x07 Ramp size depends on test injection point User Pattern 1 to User Pattern 4, then repeat User Pattern 1 to User Pattern 4, then zeros Table 31. JESD204B Sample Input for M = 2, S = 2, N' = 16 (Register 0x573[5:4] = 'b00) Frame Number 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 Converter Number 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 Sample Number 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Alternating Checkerboard 0x5555 0x5555 0x5555 0x5555 0xAAAA 0xAAAA 0xAAAA 0xAAAA 0x5555 0x5555 0x5555 0x5555 0xAAAA 0xAAAA 0xAAAA 0xAAAA 0x5555 0x5555 0x5555 0x5555 1/0 Word Toggle 0x0000 0x0000 0x0000 0x0000 0xFFFF 0xFFFF 0xFFFF 0xFFFF 0x0000 0x0000 0x0000 0x0000 0xFFFF 0xFFFF 0xFFFF 0xFFFF 0x0000 0x0000 0x0000 0x0000 Ramp (X) % 216 (X) % 216 (X) % 216 (X) % 216 (X +1) % 216 (X +1) % 216 (X +1) % 216 (X +1) % 216 (X +2) % 216 (X +2) % 216 (X +2) % 216 (X +2) % 216 (X +3) % 216 (X +3) % 216 (X +3) % 216 (X +3) % 216 (X +4) % 216 (X +4) % 216 (X +4) % 216 (X +4) % 216 Rev. C | Page 79 of 97 PN9 0x496F 0x496F 0x496F 0x496F 0xC9A9 0xC9A9 0xC9A9 0xC9A9 0x980C 0x980C 0x980C 0x980C 0x651A 0x651A 0x651A 0x651A 0x5FD1 0x5FD1 0x5FD1 0x5FD1 PN23 0xFF5C 0xFF5C 0xFF5C 0xFF5C 0x0029 0x0029 0x0029 0x0029 0xB80A 0xB80A 0xB80A 0xB80A 0x3D72 0x3D72 0x3D72 0x3D72 0x9B26 0x9B26 0x9B26 0x9B26 User Repeat UP1[15:0] UP1[15:0] UP1[15:0] UP1[15:0] UP2[15:0] UP2[15:0] UP2[15:0] UP2[15:0] UP3[15:0] UP3[15:0] UP3[15:0] UP3[15:0] UP4[15:0] UP4[15:0] UP4[15:0] UP4[15:0] UP1[15:0] UP1[15:0] UP1[15:0] UP1[15:0] User Single UP1[15:0] UP1[15:0] UP1[15:0] UP1[15:0] UP2[15:0] UP2[15:0] UP2[15:0] UP2[15:0] UP3[15:0] UP3[15:0] UP3[15:0] UP3[15:0] UP4[15:0] UP4[15:0] UP4[15:0] UP4[15:0] 0x0000 0x0000 0x0000 0x0000 Product Overview Design Resources Online Documentation Discussion Sample & Buy AD9680 Data Sheet Table 32. Physical Layer 10-bit Input (Register 0x573[5:4] = 'b01) 10-Bit Symbol Number 0 1 2 3 4 5 6 7 8 9 10 11 Alternating Checkerboard 0x155 0x2AA 0x155 0x2AA 0x155 0x2AA 0x155 0x2AA 0x155 0x2AA 0x155 0x2AA 1/0 Word Toggle 0x000 0x3FF 0x000 0x3FF 0x000 0x3FF 0x000 0x3FF 0x000 0x3FF 0x000 0x3FF Ramp (X) % 210 (X + 1) % 210 (X + 2) % 210 (X + 3) % 210 (X + 4) % 210 (X + 5) % 210 (X + 6) % 210 (X + 7) % 210 (X + 8) % 210 (X + 9) % 210 (X + 10) % 210 (X + 11) % 210 PN9 0x125 0x2FC 0x26A 0x198 0x031 0x251 0x297 0x3D1 0x18E 0x2CB 0x0F1 0x3DD PN23 0x3FD 0x1C0 0x00A 0x1B8 0x028 0x3D7 0x0A6 0x326 0x10F 0x3FD 0x31E 0x008 User Repeat UP1[15:6] UP2[15:6] UP3[15:6] UP4[15:6] UP1[15:6] UP2[15:6] UP3[15:6] UP4[15:6] UP1[15:6] UP2[15:6] UP3[15:6] UP4[15:6] User Single UP1[15:6] UP2[15:6] UP3[15:6] UP4[15:6] 0x000 0x000 0x000 0x000 0x000 0x000 0x000 0x000 Table 33. Scrambler 8-bit Input (Register 0x573[5:4] = 'b10) 8-Bit Octet Number 0 1 2 3 4 5 6 7 8 9 10 11 Alternating Checkerboard 0x55 0xAA 0x55 0xAA 0x55 0xAA 0x55 0xAA 0x55 0xAA 0x55 0xAA 1/0 Word Toggle 0x00 0xFF 0x00 0xFF 0x00 0xFF 0x00 0xFF 0x00 0xFF 0x00 0xFF Ramp (X) % 28 (X + 1) % 28 (X + 2) % 28 (X + 3) % 28 (X + 4) % 28 (X + 5) % 28 (X + 6) % 28 (X + 7) % 28 (X + 8) % 28 (X + 9) % 28 (X + 10) % 28 (X + 11) % 28 Data Link Layer Test Modes The data link layer test modes are implemented in the AD9680 as defined by section 5.3.3.8.2 in the JEDEC JESD204B Specification. These tests are shown in Register 0x574 Bits[2:0]. PN9 0x49 0x6F 0xC9 0xA9 0x98 0x0C 0x65 0x1A 0x5F 0xD1 0x63 0xAC PN23 0xFF 0x5C 0x00 0x29 0xB8 0x0A 0x3D 0x72 0x9B 0x26 0x43 0xFF User Repeat UP1[15:9] UP2[15:9] UP3[15:9] UP4[15:9] UP1[15:9] UP2[15:9] UP3[15:9] UP4[15:9] UP1[15:9] UP2[15:9] UP3[15:9] UP4[15:9] User Single UP1[15:9] UP2[15:9] UP3[15:9] UP4[15:9] 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 Test patterns inserted at this point are useful for verifying the functionality of the data link layer. When the data link layer test modes are enabled, disable SYNCINB± by writing 0xC0 to Register 0x572. Rev. C | Page 80 of 97 Design Resources Online Documentation Product Overview Discussion Data Sheet Sample & Buy AD9680 SERIAL PORT INTERFACE The AD9680 SPI allows the user to configure the converter for specific functions or operations through a structured register space provided inside the ADC. The SPI gives the user added flexibility and customization, depending on the application. Addresses are accessed via the serial port and can be written to or read from via the port. Memory is organized into bytes that can be further divided into fields. These fields are documented in the Memory Map section. For detailed operational information, see the Serial Control Interface Standard (Rev. 1.0). CONFIGURATION USING THE SPI Three pins define the SPI of the AD9680 ADC: the SCLK pin, the SDIO pin, and the CSB pin (see Table 34). The SCLK (serial clock) pin is used to synchronize the read and write data presented from/to the ADC. The SDIO (serial data input/output) pin is a dual-purpose pin that allows data to be sent and read from the internal ADC memory map registers. The CSB (chip select bar) pin is an active low control that enables or disables the read and write cycles. Table 34. Serial Port Interface Pins Pin SCLK SDIO CSB Function Serial clock. The serial shift clock input that is used to synchronize serial interface, reads, and writes. Serial data input/output. A dual-purpose pin that typically serves as an input or an output, depending on the instruction being sent and the relative position in the timing frame. Chip select bar. An active low control that gates the read and write cycles. The falling edge of CSB, in conjunction with the rising edge of SCLK, determines the start of the framing. An example of the serial timing and its definitions can be found in Figure 4 and Table 5. Other modes involving the CSB pin are available. The CSB pin can be held low indefinitely, which permanently enables the device; this is called streaming. The CSB can stall high between bytes to allow additional external timing. When CSB is tied high, SPI functions are placed in a high impedance mode. This mode turns on any SPI pin secondary functions. All data is composed of 8-bit words. The first bit of each individual byte of serial data indicates whether a read or write command is issued, which allows the SDIO pin to change direction from an input to an output. In addition to word length, the instruction phase determines whether the serial frame is a read or write operation, allowing the serial port to be used both to program the chip and to read the contents of the on-chip memory. If the instruction is a readback operation, performing a readback causes the SDIO pin to change direction from an input to an output at the appropriate point in the serial frame. Data can be sent in MSB first mode or in LSB first mode. MSB first is the default on power-up and can be changed via the SPI port configuration register. For more information about this and other features, see the Serial Control Interface Standard (Rev. 1.0). HARDWARE INTERFACE The pins described in Table 34 comprise the physical interface between the user programming device and the serial port of the AD9680. The SCLK pin and the CSB pin function as inputs when using the SPI interface. The SDIO pin is bidirectional, functioning as an input during write phases and as an output during readback. The SPI interface is flexible enough to be controlled by either FPGAs or microcontrollers. One method for SPI configuration is described in detail in the AN-812 Application Note, Microcontroller-Based Serial Port Interface (SPI) Boot Circuit. Do not activate the SPI port during periods when the full dynamic performance of the converter is required. Because the SCLK signal, the CSB signal, and the SDIO signal are typically asynchronous to the ADC clock, noise from these signals can degrade converter performance. If the on-board SPI bus is used for other devices, it may be necessary to provide buffers between this bus and the AD9680 to prevent these signals from transitioning at the converter inputs during critical sampling periods. SPI ACCESSIBLE FEATURES Table 35 provides a brief description of the general features that are accessible via the SPI. These features are described in detail in the Serial Control Interface Standard (Rev. 1.0). The AD9680 device-specific features are described in the Memory Map section. Table 35. Features Accessible Using the SPI Feature Name Mode Clock DDC Test Input/Output Output Mode SERDES Output Setup Description Allows the user to set either power-down mode or standby mode. Allows the user to access the clock divider via the SPI. Allows the user to set up decimation filters for different applications. Allows the user to set test modes to have known data on output bits. Allows the user to set up outputs. Allows the user to vary SERDES settings such as swing and emphasis. Rev. C | Page 81 of 97 Product Overview Design Resources Online Documentation Discussion AD9680 Sample & Buy Data Sheet MEMORY MAP READING THE MEMORY MAP REGISTER TABLE Logic Levels Each row in the memory map register table has eight bit locations. The memory map is divided into four sections: the Analog Devices SPI registers (Register 0x000 to Register 0x00D), the analog input buffer control registers, the ADC function registers, the DDC function registers, and the digital outputs and test modes registers. An explanation of logic level terminology follows: Table 36 (see the Memory Map Register Table section) documents the default hexadecimal value for each hexadecimal address shown. The column with the heading Bit 7 (MSB) is the start of the default hexadecimal value given. For example, Address 0x561, the output mode register, has a hexadecimal default value of 0x01, which means that Bit 0 = 1, and the remaining bits are 0s. This setting is the default output format value, which is twos complement. For more information on this function and others, see Table 36. Open and Reserved Locations All address and bit locations that are not included in Table 36 are not currently supported for this device. Write unused bits of a valid address location with 0s unless the default value is set otherwise. Writing to these locations is required only when part of an address location is unassigned (for example, Address 0x561). If the entire address location is open (for example, Address 0x13), do not write to this address location. Default Values After the AD9680 is reset, critical registers are loaded with default values. The default values for the registers are given in the memory map register table, Table 36. • • • “Bit is set” is synonymous with “bit is set to Logic 1” or “writing Logic 1 for the bit.” “Clear a bit” is synonymous with “bit is set to Logic 0” or “writing Logic 0 for the bit.” X denotes a don’t care bit. Channel-Specific Registers Some channel setup functions, such as the input termination (Register 0x016), can be programmed to a different value for each channel. In these cases, channel address locations are internally duplicated for each channel. These registers and bits are designated in Table 36 as local. These local registers and bits can be accessed by setting the appropriate Channel A or Channel B bits in Register 0x008. If both bits are set, the subsequent write affects the registers of both channels. In a read cycle, set only Channel A or Channel B to read one of the two registers. If both bits are set during an SPI read cycle, the device returns the value for Channel A. Registers and bits designated as global in Table 36 affect the entire device and the channel features for which independent settings are not allowed between channels. The settings in Register 0x005 do not affect the global registers and bits. SPI Soft Reset After issuing a soft reset by programming 0x81 to Register 0x000, the AD9680 requires 5 ms to recover. When programming the AD9680 for application setup, ensure that an adequate delay is programmed into the firmware after asserting the soft reset and before starting the device setup. Rev. C | Page 82 of 97 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet AD9680 MEMORY MAP REGISTER TABLE All address locations that are not included in Table 36 are not currently supported for this device and should not be written. Table 36. Memory Map Registers Reg Addr Register Bit 7 (Hex) Name (MSB) Analog Devices SPI Registers INTERFACE_ Soft reset 0x000 CONFIG_A (self clearing) INTERFACE_ Single 0x001 CONFIG_B instruction 0x002 0x003 0x004 0x005 0x006 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (LSB) LSB first 0 = MSB 1 = LSB 0 Address ascension 0 0 0 0 0 0 0 0 0 Soft reset LSB first (self 0 = MSB clearing) 1 = LSB Datapath 0 0 soft reset (self clearing) 00 = normal operation 0 10 = standby 11 = power-down 011 = high speed ADC 0x03 Address ascension Default 0x00 0x00 DEVICE_ CONFIG (local) CHIP_TYPE 0 CHIP_ID (low byte) CHIP_ID (high byte) CHIP_ GRADE 1 1 0 0 0 1 0 1 0xC5 0 0 0 0 0 0 0 0 0x00 X X X X 0x008 0x00A 0x00B 0x00C Device index 0 Scratch pad 0 SPI revision 0 Vendor ID 0 (low byte) Vendor ID 0x00D 0 (high byte) Analog Input Buffer Control Registers Analog input 0x015 0 (local) 0x016 Input termination (local) 0x934 Input capacitance (local) 0 0 0 1 0 0 0 0 0 0 0 1 Channel B 0 0 1 Channel A 0 1 0 0x0 0x00 0x01 0x56 0 0 0 0 1 0 0 0x04 0 0 0 0 Analog input differential termination 0000 = 400 Ω (default) 0001 = 200 Ω 0010 = 100 Ω 0110 = 50 Ω 0 0x00 1100 = 1250 MSPS 1010 = 1000 MSPS 1000 = 820 MSPS 0101 = 500 MSPS 0 0 0 0 0 0 1 0 0 0 Input disable 0= normal operation 1 = input disabled 1110 = AD9680-1250 and AD9680-1000 1100 = AD9680-820 and AD9680-500 0 0 0x1F = 3 pF to GND (default) 0x00 = 1.5 pF to GND Rev. C | Page 83 of 97 Notes 0x00 0x0E for AD96801250 and AD96801000; 0x0C for AD9680820 and AD9680500 0x1F Read only Read only Read only Read only Read only Read only Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Reg Addr (Hex) 0x018 Register Name Buffer Control 1 (local) Data Sheet Bit 7 (MSB) Bit 6 Bit 5 Bit 4 0000 = 1.0× buffer current 0001 = 1.5× buffer current 0010 = 2.0× buffer current (default for AD9680-500) 0011 = 2.5× buffer current 0100 = 3.0× buffer current (default for AD9680-1000 and AD9680-820) 0101 = 3.5× buffer current (default for AD9680-1250) … 1111 = 8.5× buffer current 0100 = Setting 1 (default for AD9680-820) 0101 = Setting 2 (default for AD9680-1250 and AD9680-1000) 0110 = Setting 3 (default for AD9680-500) 0111 = Setting 4 Bit 3 0 Bit 2 0 0 Bit 1 0 0x019 Buffer Control 2 (local) 0x01A Buffer Control 3 (local) 0 0 0 0 0x11A Buffer Control 4 (local) 0 0 0 0 0x935 Buffer Control 5 (local) 0 0 High frequency setting 0 = off (default) 1 = on 0 0 0 0x025 Input fullscale range (local) 0 0 0 0 0x030 Input fullscale control (local) 0 0 0 Full-scale control See Table 10 for recommended settings for different frequency bands; default values: AD9680-1250, AD9680-1000 = 110 AD9680-820 = 101 AD9680-500 = 001 AD9680-500 = 110 (for <1.82 V) 0 0 Bit 0 (LSB) 0 0 1000 = Setting 1 1001 = Setting 2 (default for AD9680-1250, AD9680-1000 and AD9680-820) 1010 = Setting 3 (default for AD9680-500) 0 0 Rev. C | Page 84 of 97 Notes 0x09 for AD96801250; 0x0A for AD96801000 and AD9680820; 0x0C for AD9680500 V p-p differential; use in conjunction with Reg. 0x030 0 Low 0 0 frequency operation 0 = off 1 = on (default) Full-scale adjust 0000 = 1.94 V 1000 = 1.46 V 1001 = 1.58 V (default for AD9680-1250) 1010 = 1.70 V (default for AD9680-1000 and AD9680-820) 1011 = 1.82 V 1100 = 2.06 V (default for AD9680-500) 0 Default 0x50 for AD96801250; 0x40 for AD96801000 and AD9680820; 0x20 for AD9680500 0x50 for AD96801250 and AD96801000; 0x40 for AD9680820; 0x60 for AD9680500 0x09 for AD96801250, AD96801000 and AD9680820; 0x0A for AD9680500 0 Used in conjunction with Reg. 0x025 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet Reg Addr Register (Hex) Name ADC Function Registers V_1P0 0x024 control AD9680 Bit 7 (MSB) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (LSB) Default 0 0 0 0 0 0 0 0x00 0 0 0 0 0 0 0 0 1.0 V reference select 0= internal 1= external Diode selection 0= no diode selected 1= temperature diode selected 0 0x028 Temperature diode 0 0x03F PDWN/ STBY pin control (local) 0x040 Chip pin control 0 = PDWN/ 0 STBY enabled 1= disabled PDWN/STBY function 00 = power down 01 = standby 10 = disabled 0x10B Clock divider 0 0x10C Clock divider phase (local) 0 0x10D Clock divider and SYSREF control Clock divider auto phase adjust 0= disabled 1= enabled 0x117 Clock delay control 0 0 0 0 Fast Detect A (FD_A) 000 = Fast Detect A output 001 = JESD204B LMFC output 010 = JESD204B internal SYNC~ output 011 = temperature diode 111 = disabled 000 = divide by 1 0 001 = divide by 2 011 = divide by 4 111 = divide by 8 Independently controls Channel A and Channel B clock divider phase offset 0000 = 0 input clock cycles delayed 0001 = ½ input clock cycles delayed 0010 = 1 input clock cycles delayed 0011 = 1½ input clock cycles delayed 0100 = 2 input clock cycles delayed 0101 = 2½ input clock cycles delayed … 1111 = 7½ input clock cycles delayed Clock divider positive Clock divider negative skew window skew window 00 = no positive skew 00 = no negative skew 01 = 1 device clock of 01 = 1 device clock of positive skew negative skew 10 = 2 device clocks of 10 = 2 device clocks of positive skew negative skew 11 = 3 device clocks of 11 = 3 device clocks of positive skew negative skew Clock fine 0 0 0 delay adjust enable 0= disabled 1= enabled 0x00 Used in conjunction with Reg. 0x040 0x00 Used in conjunction with Reg. 0x040 Fast Detect B (FD_B) 000 = Fast Detect B output 001 = JESD204B LMFC output 010 = JESD204B internal SYNC~ output 111 = disabled 0x3F 0 0 0 0x00 0 0 0 0 0 0 0 0 0 Rev. C | Page 85 of 97 Notes 0x00 0x00 0x00 Clock divider must be >1 Enabling the clock fine delay adjust causes a datapath reset Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Reg Addr (Hex) 0x118 Data Sheet Register Name Clock fine delay (local) Bit 7 (MSB) 0x11C Clock status 0 0x120 SYSREF± Control 1 0 0x121 SYSREF± Control 2 0 0x123 SYSREF± timestamp delay control 0x128 SYSREF± Status 1 SYSREF± and clock divider status 0x129 0x12A 0x1FF Bit 6 Bit 4 Bit 3 Bit 2 Bit 1 Clock Fine Delay Adjust[7:0], twos complement coded control to adjust the fine sample clock skew in ~1.7 ps steps ≤ −88 = −151.7 ps skew −87 = −150 ps skew … 0 = 0 ps skew … ≥ +87 = +150 ps skew 0 0 0 0 0 0 SYSREF± flag reset 0= normal operation 1 = flags held in reset 0 Bit 5 Bit 0 (LSB) Default 0x00 Read only 0 SYSREF± transition select 0 = low to high 1 = high to low 0 = no input clock detected 1 = input clock detected 0 0 0 CLK± edge select 0 = rising 1 = falling SYSREF± mode select 00 = disabled 01 = continuous 10 = N shot SYSREF N-shot ignore counter select 0000 = next SYSREF± only 0001 = ignore the first SYSREF± transition 0010 = ignore the first two SYSREF± transitions … 1111 = ignore the first 16 SYSREF± transitions SYSREF± timestamp delay, Bits[6:0] 0x00 = no delay 0x01 = 1 clock delay … 0x7F = 127 clocks delay SYSREF± hold status, Register 0x128[7:4], SYSREF± setup status, Register 0x128[3:0], refer to Table 28 refer to Table 28 Clock divider phase when SYSREF± was captured 0 0 0 0 0000 = in-phase 0001 = SYSREF± is ½ cycle delayed from clock 0010 = SYSREF± is 1 cycle delayed from clock 0011 = 1½ input clock cycles delayed 0100 = 2 input clock cycles delayed 0101 = 2½ input clock cycles delayed … 1111 = 7½ input clock cycles delayed SYSREF counter, Bits[7:0] increments when a SYSREF± is captured SYSREF± counter Chip sync mode 0x200 Chip application mode 0 0 0x201 Chip decimation ratio 0 0 0x228 Customer offset Synchronization mode 00 = normal 01 = timestamp Chip operating mode Chip Q 0 0 0 00 = full bandwidth mode ignore 01 = DDC 0 on 0 = normal 10 = DDC 0 and DDC 1 on (I/Q) 11 = DDC 0, DDC 1, 1 = ignore DDC 2, and DDC 3 on (I only) Chip decimation ratio select 0 0 0 000 = full sample rate (decimate = 1) 001 = decimate by 2 010 = decimate by 4 011 = decimate by 8 100 = decimate by 16 Offset adjust in LSBs from +127 to −128 (twos complement format) Rev. C | Page 86 of 97 Notes Used in conjunction with Reg. 0x0117 0x00 0x00 0x00 Read only Read only Read only 0x00 0x00 0x00 0x00 Mode select (Reg 0x120, Bits [2:1]) must be N-shot Ignored when Reg. 0x01FF = 0x00 Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet Reg Addr (Hex) 0x245 0x247 0x248 0x249 0x24A 0x24B 0x24C 0x26F Register Name Fast detect (FD) control (local) FD upper threshold LSB (local) FD upper threshold MSB (local) FD lower threshold LSB (local) FD lower threshold MSB (local) FD dwell time LSB (local) FD dwell time MSB (local) Signal monitor synchronization control 0x270 Signal monitor control (local) 0x271 Signal Monitor Period Register 0 (local) Signal Monitor Period Register 1 (local) Signal Monitor Period Register 2 (local) Signal monitor result control (local) 0x272 0x273 0x274 0x275 Signal Monitor Result Register 0 (local) AD9680 Bit 7 (MSB) 0 Bit 6 0 0 Bit 5 0 0 Bit 4 0 Bit 3 Bit 2 Force value of Force FD_A/FD_B FD_A/ FD_B pins; pins if force 0 = normal pins is true, this value is function; output on FD 1 = force pins to value Fast detect upper threshold, Bits[7:0] 0 Bit 1 0 Bit 0 (LSB) Enable fast detect output 0 Fast detect upper threshold, Bits[12:8] 0 0x00 0x00 Fast detect dwell time, Bits[7:0] 0x00 Fast detect dwell time, Bits[15:8] 0x00 0 0 0 0 0 0 0 0 0 0 0 0 0x00 Fast detect lower threshold, Bits[12:8] 0 Synchronization mode 00 = disabled 01 = continuous 11 = one shot Peak detector 0= disabled 1= enabled 0 0x00 0x80 Signal monitor period, Bits[15:8] 0x00 Signal monitor period, Bits[23:16] 0x00 0 Rev. C | Page 87 of 97 Refer to the Signal Monitor section 0x00 Signal monitor period, Bits[7:0] Result Result 0 0 0 selection update 0= 1= reserved update 1 = peak results detector (self clear) Signal monitor result, Bits[7:0] When Register 0x0274[0] = 1, Result Bits[19:7] = Peak Detector Absolute Value[12:0]; Result Bits[6:0] = 0 0 Notes 0x00 Fast detect lower threshold, Bits[7:0] 0 Default 0x00 In decimated output clock cycles In decimated output clock cycles In decimated output clock cycles 0x01 Read only Updated based on Reg. 0x274[4] Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Reg Addr (Hex) 0x276 0x277 0x278 0x279 0x27A Register Name Signal Monitor Result Register 1 (local) Signal Monitor Result Register 1 (local) Signal monitor period counter result (local) Signal monitor SPORT over JESD204B control (local) SPORT over JESD204B input selection (local) Data Sheet Bit 7 (MSB) 0 Bit 6 0 Bit 5 0 Bit 4 Bit 3 Bit 2 Signal monitor result, Bits[15:8] 0 DDC 0 input selection 0x314 DDC 0 frequency LSB DDC 0 frequency MSB DDC 0 phase LSB DDC 0 phase MSB 0x315 0x320 0x321 Bit 0 (LSB) Signal monitor result, Bits[19:16] Period count result, Bits[7:0] 0 0 0 0 0 0 0 0 0 0 0 0 DDC Function Registers (See the Digital Downconverter (DDC) Section) DDC NCO DDC 0 0 0 0x300 soft reset synchro0 = normal nization operation control 1 = reset IF (intermediate Gain DDC 0 Mixer 0x310 frequency) mode select control select 00 = variable IF mode 0 = 0 dB 0 = real (mixers and NCO gain mixer enabled) 1 = 6 dB 1= 01 = 0 Hz IF mode (mixer gain complex bypassed, NCO disabled) mixer 10 = fS/4 Hz IF mode (fs/4 downmixing mode) 11 = test mode (mixer inputs forced to +fS, NCO enabled) 0x311 Bit 1 0 X X 0 X X 0 X X 0 0 Complex to real enable 0= disabled 1= enabled 0 Q input select 0 = Ch A 1 = Ch B DDC 0 NCO frequency value, Bits[7:0] twos complement 0 X 0 00 = disabled 11 = enable Peak detector 0= disabled 1= enabled 0 Synchronization mode (triggered by SYSREF±) 00 = disabled 01 = continuous 11 = one shot Decimation rate select (complex to real disabled) 11 = decimate by 2 00 = decimate by 4 01 = decimate by 8 10 = decimate by 16 (complex to real enabled) 11 = decimate by 1 00 = decimate by 2 01 = decimate by 4 10 = decimate by 8 I input 0 select 0 = Ch A 1 = Ch B DDC 0 NCO frequency value, Bits[11:8] twos complement DDC 0 NCO phase value, Bits[7:0] twos complement DDC 0 NCO phase value, Bits[11:8] X twos complement Rev. C | Page 88 of 97 Default Read only Notes Updated based on Reg. 0x274[4] Read only Updated based on Reg. 0x274[4] Read only Updated based on Reg. 0x274[4] 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00 Refer to the DDC section Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet Reg Addr (Hex) 0x327 AD9680 Register Name DDC 0 output test mode selection Bit 7 (MSB) 0 0x330 DDC 1 control 0x331 DDC 1 input selection 0x334 DDC 1 frequency LSB DDC 1 frequency MSB DDC 1 phase LSB DDC 1 phase MSB DDC 1 output test mode selection 0x335 0x340 0x341 0x347 Bit 6 0 Bit 5 0 Mixer select 0 = real mixer 1= complex mixer Gain select 0 = 0 dB gain 1 = 6 dB gain 0 0 IF (intermediate frequency) mode 00 = variable IF mode (mixers and NCO enabled) 01 = 0 Hz IF mode (mixer bypassed, NCO disabled) 10 = fADC/4 Hz IF mode (fADC/4 downmixing mode) 11 = test mode (mixer inputs forced to +fS, NCO enabled) 0 0 X X X X 0 0 0x350 DDC 2 control Mixer select 0 = real mixer 1= complex mixer Gain select 0 = 0 dB gain 1 = 6 dB gain 0x351 DDC 2 input selection 0 0 0x354 DDC 2 frequency LSB Bit 4 0 Bit 3 0 Bit 2 Q output test mode enable 0 = disabled 1 = enabled from Channel B Complex to real enable 0= disabled 1= enabled 0 Q input select 0 = Ch A 1 = Ch B DDC 1 NCO frequency value, Bits[7:0] twos complement X X 0 Bit 1 0 Bit 0 (LSB) I output test mode enable 0= disabled 1= enabled from Channel A Decimation rate select (complex to real disabled) 11 = decimate by 2 00 = decimate by 4 01 = decimate by 8 10 = decimate by 16 (complex to real enabled) 11 = decimate by 1 00 = decimate by 2 01 = decimate by 4 10 = decimate by 8 I input 0 select 0 = Ch A 1 = Ch B DDC 1 NCO frequency value, Bits[11:8] twos complement DDC 1 NCO phase value, Bits[7:0] twos complement DDC 1 NCO phase value, Bits[11:8] X X twos complement I output Q output 0 0 0 0 test mode test mode enable enable 0= 0 = disabled disabled 1 = enabled 1= from Ch B enabled from Ch A IF mode Decimation rate select Complex 0 00 = variable IF mode (complex to real to real (mixers and NCO disabled) enable enabled) 11 = decimate by 2 0= 01 = 0 Hz IF mode (mixer disabled 00 = decimate by 4 bypassed, NCO disabled) 1 = 01 = decimate by 8 10 = fADC/4 Hz IF mode 10 = decimate by 16 enabled (complex to real (fADC/4 downmixing enabled) mode) 11 = decimate by 1 11 = test mode (mixer 00 = decimate by 2 inputs forced to +fS, 01 = decimate by 4 NCO enabled) 10 = decimate by 8 I input Q input 0 0 0 0 select select 0 = Ch A 0 = Ch A 1 = Ch B 1 = Ch B DDC 2 NCO frequency value, Bits[7:0] twos complement Rev. C | Page 89 of 97 Default 0x00 Notes Refer to the DDC section 0x00 0x05 Refer to the DDC section 0x00 0x00 0x00 0x00 0x00 Refer to the DDC section 0x00 0x00 0x00 Refer to the DDC section Design Resources Online Documentation Product Overview Discussion Sample & Buy AD9680 Reg Addr (Hex) 0x355 Data Sheet Register Name DDC2 frequency MSB DDC 2 phase LSB DDC 2 phase MSB DDC 2 output test mode selection Bit 7 (MSB) X 0x370 0x360 0x361 Bit 6 X X X 0 0 DDC 3 control Mixer select 0 = real mixer 1= complex mixer Gain select 0 = 0 db gain 1 = 6 db gain 0x371 DDC 3 input selection 0 0 0x374 DDC 3 frequency LSB DDC 3 frequency MSB DDC3 phase LSB DDC 3 phase MSB DDC 3 output test mode selection 0x367 0x375 0x380 0x381 0x387 X X Bit 5 X Bit 3 Bit 2 Bit 1 Bit 0 (LSB) DDC 2 NCO frequency value, Bits[11:8] twos complement DDC 2 NCO phase value, Bits[7:0] twos complement DDC 2 NCO phase value, Bits[11:8] X X twos complement I output Q output 0 0 0 0 test mode test mode enable enable 0= 0 = disabled disabled 1 = enabled 1= from Ch B enabled from Ch A IF mode Complex Decimation rate select 0 00 = variable IF mode to real (complex to real (mixers and NCO enable disabled) enabled) 0= 11 = decimate by 2 01 = 0 Hz IF mode(mixer disabled 00 = decimate by 4 bypassed, NCO disabled) 1 = 01 = decimate by 8 10 = fADC/4 Hz IF mode enabled 10 = decimate by 16 (complex to real (fADC/4 downmixing enabled) mode) 11 = decimate by 1 11 = test mode (mixer 00 = decimate by 2 inputs forced to +fS, 01 = decimate by 4 NCO enabled) 10 = decimate by 8 I input Q input 0 0 0 0 select select 0 = Ch A 0 = Ch A 1 = Ch B 1 = Ch B DDC 3 NCO frequency value, Bits[7:0] twos complement X X X X 0 0 0 0 Reset PN long gen 0 = long PN enable 1 = long PN reset Digital Outputs and Test Modes User ADC test 0x550 pattern modes selection (local) 0 = continuous repeat 1 = single pattern Bit 4 X DDC 3 NCO frequency value, Bits[11:8] twos complement X DDC 3 NCO phase value, Bits[7:0] twos complement DDC 3 NCO phase value, Bits[11:8] X twos complement I output 0 0 0 0 test mode enable 0= disabled 1= enabled from Ch A Reset PN short gen 0 = short PN enable 1 = short PN reset Test mode selection 0000 = off, normal operation 0001 = midscale short 0010 = positive full scale 0011 = negative full scale 0100 = alternating checker board 0101 = PN sequence, long 0110 = PN sequence, short 0111 = 1/0 word toggle 1000 = the user pattern test mode (used with Register 0x0550, Bit 7 and User Pattern 1 to User Pattern 4 registers) 1111 = ramp output Rev. C | Page 90 of 97 Default 0x00 Notes 0x00 0x00 0x00 Refer to the DDC section 0x00 0x05 Refer to the DDC section 0x00 0x00 0x00 0x00 0x00 0x00 Refer to the DDC section Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet Reg Addr (Hex) 0x551 AD9680 Register Name User Pattern 1 LSB Bit 7 (MSB) 0 Bit 6 0 Bit 5 0 Bit 4 0 Bit 3 0 Bit 2 0 Bit 1 0 Bit 0 (LSB) 0 Default 0x00 0x552 User Pattern 1 MSB 0 0 0 0 0 0 0 0 0x00 0x553 User Pattern 2 LSB 0 0 0 0 0 0 0 0 0x00 0x554 User Pattern 2 MSB 0 0 0 0 0 0 0 0 0x00 0x555 User Pattern 3 LSB 0 0 0 0 0 0 0 0 0x00 0x556 User Pattern 3 MSB 0 0 0 0 0 0 0 0 0x00 0x557 User Pattern 4 LSB 0 0 0 0 0 0 0 0 0x00 0x558 User Pattern 4 MSB 0 0 0 0 0 0 0 0 0x00 0x559 Output Mode Control 1 0 0 Converter Control Bit 0 selection 000 = tie low (1’b0) 001 = overrange bit 011 = fast detect (FD) bit 101 = SYSREF± Only used when CS (Register 0x58F) = 3 0x00 0x55A Output Mode Control 2 0 Converter Control Bit 1 selection 000 = tie low (1’b0) 001 = overrange bit 011 = fast detect (FD) bit 101 = SYSREF± Only used when CS (Register 0x58F) = 2 or 3 0 0 0 0 0x01 0x561 Output mode 0 0 0 0x562 Output overrange (OR) clear Converter Control Bit 2 selection 000 = tie low (1’b0) 001 = overrange bit 011 = fast detect (FD) bit 101 = SYSREF Used when CS (Register 0x58F) = 1, 2, or 3 Data format select Sample 00 = offset binary invert 01 = twos complement 0 = normal 1 = sample invert Virtual Virtual Virtual Converter 1 Converter Converter 2 0 OR OR OR 0 = OR bit 0 = OR bit 0 = OR bit enabled enabled enabled 1 = OR bit 1 = OR bit 1 = OR bit cleared cleared cleared Virtual Converter 7 OR 0 = OR bit enabled 1 = OR bit cleared Virtual Converter 6 OR 0 = OR bit enabled 1 = OR bit cleared 0 Virtual Converter 5 OR 0 = OR bit enabled 1 = OR bit cleared 0 Virtual Converter 4 OR 0 = OR bit enabled 1 = OR bit cleared Virtual Converter 3 OR 0 = OR bit enabled 1 = OR bit cleared Rev. C | Page 91 of 97 0x01 0x00 Notes Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Used with Reg. 0x550 and Reg. 0x573 Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Reg Addr (Hex) 0x563 Register Name Output OR status Data Sheet Bit 7 (MSB) Virtual Converter 7 OR 0 = no OR 1 = OR occurred Bit 6 Virtual Converter 6 OR 0 = no OR 1 = OR occurred 0 Bit 5 Virtual Converter 5 OR 0 = no OR 1 = OR occurred 0x564 Output channel select 0 0x56E JESD204B lane rate control 0 0 0 0x56F JESD204B PLL lock status PLL lock 0 = not locked 1 = locked 0 0 0x570 JESD204B quick configuration 0x571 JESD204B Link Mode Control 1 Standby mode 0 = all converter outputs 0 1 = CGS (/K28.5/) 0x572 JESD204B Link Mode Control 2 SYNCINB± pin control 00 = normal 10 = ignore SYNCINB± (force CGS) 11 = ignore SYNCINB± (force ILAS/user data) 0 Bit 4 Virtual Converter 4 OR 0 = no OR 1 = OR occurred 0 0 = serial lane rate ≥6.25 Gbps and ≤12.5 Gbps 1 = serial lane rate must be ≥ 3.125 Gbps and ≤6.25 Gbps 0 Bit 3 Virtual Converter 3 OR 0 = no OR 1 = OR occurred Bit 2 Virtual Converter 2 OR 0 = no OR 1 = OR occurred Bit 1 Virtual Converter 1 OR 0 = no OR 1 = OR occurred Bit 0 (LSB) Virtual Converter 0 OR 0 = no OR 1 = OR occurred Default 0x00 0x00 0x00 Read only 0x88 for AD96801250, AD96801000 and AD9680820; 0x49 for AD9680500 0x14 Refer to Table 26 and Table 27 0 0 0 0 0 0 Converter channel swap 0= normal channel ordering 1= channel swap enabled 0 0 0 0 0 JESD204B quick configuration L = number of lanes = 2Register 0x570, Bits[7:6] M = number of converters = 2Register 0x570, Bits[5:3] F = number of octets/frame = 2 Register 0x570, Bits[2:0] Tail bit (t) PN 0= disable 1= enable T = N΄ − N − CS Long transport layer test 0= disable 1= enable SYNCINB± pin invert 0 = active low 1 = active high Lane synchronization 0 = disable FACI uses /K28.7/ 1 = enable FACI uses /K28.3/ and /K28.7/ SYNCINB± pin type 0= differential 1 = CMOS ILAS sequence mode 00 = ILAS disabled 01 = ILAS enabled 11 = ILAS always on test mode 0 Rev. C | Page 92 of 97 8-bit/10-bit bypass 0 = normal 1 = bypass FACI 0= enabled 1= disabled Link control 0 = active 1 = power down 8-/10-bit bit invert 0= normal 1 = invert the abcd efghij symbols 0 Notes Read only 0x00 for AD96801250, AD96801000 and AD9680820; 0x10 for AD9680500 0x00 Design Resources Online Documentation Product Overview Discussion Sample & Buy Data Sheet Reg Addr (Hex) 0x573 AD9680 Register Name JESD204B Link Mode Control 3 Bit 7 (MSB) Bit 6 CHKSUM mode 00 = sum of all 8-bit link config registers 01 = sum of individual link config fields 10 = checksum set to zero 0x574 JESD204B Link Mode Control 4 0x578 JESD204B LMFC offset JESD204B DID config JESD204B BID config JESD204B LID Config 1 JESD204B LID Config 2 JESD204B LID Config 3 JESD204B LID Config 4 JESD204B parameters SCR/L ILAS delay 0000 = transmit ILAS on first LMFC after SYNCINB± deasserted 0001 = transmit ILAS on second LMFC after SYNCINB± deasserted … 1111 = transmit ILAS on 16th LMFC after SYNCINB± deasserted 0 0 0 0x580 0x581 0x583 0x584 0x585 0x586 0x58B 0 Bit 2 Bit 1 Bit 0 (LSB) JESD204B test mode patterns 0000 = normal operation (test mode disabled) 0001 = alternating checker board 0010 = 1/0 word toggle 0011 = 31-bit PN sequence—X31 + X28 + 1 0100 = 23-bit PN sequence—X23 + X18 + 1 0101 = 15-bit PN sequence—X15 + X14 + 1 0110 = 9-bit PN sequence—X9 + X5 + 1 0111 = 7-bit PN sequence—X7 + X6 + 1 1000 = ramp output 1110 = continuous/repeat user test 1111 = single user test Link layer test mode 000 = normal operation (link layer test mode disabled) 001 = continuous sequence of /D21.5/ characters 100 = modified RPAT test sequence 101 = JSPAT test sequence 110 = JTSPAT test sequence LMFC phase offset value[4:0] Default 0x00 0x00 JESD204B Tx DID value[7:0] 0x00 0 0x00 0 0 0 0 Lane 0 LID value, Bits[4:0] 0x00 0 0 0 Lane 1 LID value, Bits[4:0] 0x01 0 0 0 Lane 2 LID value, Bits[4:0] 0x01 0 0 0 Lane 3 LID value, Bits[4:0] 0x03 JESD204B scrambling (SCR) 0= disabled 1= enabled 0 0 0x58D JESD204B K config JESD204B M config 0 JESD204B CS/N config Number of control bits (CS) per sample 00 = no control bits (CS = 0) 01 = 1 control bit (CS = 1); Control Bit 2 only 10 = 2 control bits (CS = 2); Control Bit 2 and 1 only 11 = 3 control bits (CS = 3); all control bits (2, 1, 0) 0 JESD204B Tx BID value, Bits[3:0] 0 0 JESD204B lanes (L) 00 = 1 lane 01 = 2 lanes 11 = 4 lanes Read only, see Register 0x570 Number of octets per frame, F = Register 0x58C[7:0] + 1 0 Number of frames per multiframe, K = Register 0x58D[4:0] + 1 Only values where (F × K) mod 4 = 0 are supported Number of Converters per Link[7:0] 0x00 = link connected to one virtual converter (M = 1) 0x01 = link connected to two virtual converters (M = 2) 0x03 = link connected to four virtual converters (M = 4) 0x07 = link connected to eight virtual converters (M = 8) ADC converter resolution (N) 0 0x06 = 7-bit resolution 0x07 = 8-bit resolution 0x08 = 9-bit resolution 0x09 = 10-bit resolution 0x0A = 11-bit resolution 0x0B = 12-bit resolution 0x0C = 13-bit resolution 0x0D = 14-bit resolution 0x0E = 15-bit resolution 0x0F = 16-bit resolution 0 Rev. C | Page 93 of 97 Notes 0x00 0 JESD204B F config 0x58F Bit 3 0 0x58C 0x58E Bit 5 Bit 4 Test injection point 00 = N΄ sample input 01 = 10-bit data at 8-bit/10-bit output (for PHY testing) 10 = 8-bit data at scrambler input 0x8X 0x88 0x1F 0x0F Read only, see Reg. 0x570 See Reg. 0x570 Read only Design Resources Online Documentation Product Overview Sample & Buy Discussion AD9680 Reg Addr (Hex) 0x590 0x591 0x592 0x5A0 0x5A1 0x5A2 0x5A3 Data Sheet Register Name JESD204B N’ config Bit 7 (MSB) 0 Bit 6 0 JESD204B S config JESD204B HD and CF config 0 0 HD value 0= disabled 1= enabled 0 JESD204B CHKSUM 0 JESD204B CHKSUM 1 JESD204B CHKSUM 2 JESD204B CHKSUM 3 JESD204B lane powerdown Bit 5 Subclass support (Subclass V) 0= Subclass 0 (no deterministic latency) 1= Subclass 1 1 Bit 4 Bit 3 Bit 2 Bit 1 ADC number of bits per sample (N’) 0x7 = 8 bits 0xF = 16 bits Samples per converter frame cycle (S) S value = Register 0x591[4:0] + 1 Control words per frame clock cycle per link (CF) CF value = Register 0x592, Bits[4:0] 0 0x20 Read only Read only 0x80 CHKSUM value for SERDOUT1±, Bits[7:0] 0x82 CHKSUM value for SERDOUT2±, Bits[7:0] 0x82 CHKSUM value for SERDOUT3±, Bits[7:0] 0x84 X SERDOUT2± 0 = on 1 = off X JESD204B lane SERDOUT0± assign X 0 0x5B3 JESD204B lane SERDOUT1± assign X X X X 0 0x5B5 JESD204B lane SERDOUT2± assign X X X X 0 0x5B6 JESD204B lane SERDOUT3± assign X X X X 0 0x5BF JESD serializer drive adjust 0 0 0 0 1 Notes 0x81 0x5B2 1 Default 0x2F CHKSUM value for SERDOUT0±, Bits[7:0] SERDOUT3± 0 = on 1 = off X 0x5B0 Bit 0 (LSB) 1 Rev. C | Page 94 of 97 SERDSERD1 OUT1± OUT0± 0 = on 0 = on 1 = off 1 = off SERDOUT0± lane assignment 000 = Logical Lane 0 001 = Logical Lane 1 010 = Logical Lane 2 011 = Logical Lane 3 SERDOUT1± lane assignment 000 = Logical Lane 0 001 = Logical Lane 1 010 = Logical Lane 2 011 = Logical Lane 3 SERDOUT2± lane assignment 000 = Logical Lane 0 001 = Logical Lane 1 010 = Logical Lane 2 011 = Logical Lane 3 SERDOUT3± lane assignment 000 = Logical Lane 0 001 = Logical Lane 1 010 = Logical Lane 2 011 = Logical Lane 3 Swing voltage 0000 = 237.5 mV 0001 = 250 mV 0010 = 262.5 mV 0011 = 275 mV 0100 = 287.5 mV 0101 = 300 mV (default) 0110 = 312.5 mV 0111 = 325 mV 1000 = 337.5 mV 1001 = 350 mV 1010 = 362.5 mV 1011 = 375 mV 1100 = 387.5 mV 1101 = 400 mV 1110 = 412.5 mV 1111 = 425 mV 0xAA 0x00 0x11 0x22 0x33 0x05 Read only Read only Read only Read only Design Resources Online Documentation Product Overview Sample & Buy Discussion Data Sheet Reg Addr (Hex) 0x5C1 AD9680 Register Name De-emphasis select Bit 7 (MSB) 0 0x5C2 De-emphasis setting for SERDOUT0± 0x5C3 0 Bit 6 SERDOUT3± 0= disable 1= enable 0 Bit 5 0 0 Bit 4 SERDOUT2± 0= disable 1= enable 0 De-emphasis setting for SERDOUT1± 0 0 0 0 0x5C4 De-emphasis setting for SERDOUT2± 0 0 0 0 0x5C5 De-emphasis setting for SERDOUT3± 0 0 0 0 Bit 3 0 Rev. C | Page 95 of 97 Bit 2 SERDOUT1± 0 = disable 1 = enable Bit 1 0 Bit 0 (LSB) SERDOUT0± 0 = disable 1 = enable SERDOUT0± de-emphasis settings 0000 = 0 dB 0001 = 0.3 dB 0010 = 0.8 dB 0011 = 1.4 dB 0100 = 2.2 dB 0101 = 3.0 dB 0110 = 4.0 dB 0111 = 5.0 dB SERDOUT1± de-emphasis settings 0000 = 0 dB 0001 = 0.3 dB 0010 = 0.8 dB 0011 = 1.4 dB 0100 = 2.2 dB 0101 = 3.0 dB 0110 = 4.0 dB 0111 = 5.0 dB SERDOUT2± de-emphasis settings 0000 = 0 dB 0001 = 0.3 dB 0010 = 0.8 dB 0011 = 1.4 dB 0100 = 2.2 dB 0101 = 3.0 dB 0110 = 4.0 dB 0111 = 5.0 dB SERDOUT3± de-emphasis settings 0000 = 0 dB 0001 = 0.3 dB 0010 = 0.8 dB 0011 = 1.4 dB 0100 = 2.2 dB 0101 = 3.0 dB 0110 = 4.0 dB 0111 = 5.0 dB Default 0x00 0x00 0x00 0x00 0x00 Notes Product Overview Design Resources Online Documentation AD9680 Discussion Sample & Buy Data Sheet APPLICATIONS INFORMATION POWER SUPPLY RECOMMENDATIONS The AD9680 must be powered by the following seven supplies: AVDD1 = 1.25 V, AVDD2 = 2.5 V, AVDD3 = 3.3 V, AVDD1_SR = 1.25 V, DVDD = 1.25 V, DRVDD = 1.25 V, and SPIVDD = 1.80 V. For applications requiring an optimal high power efficiency and low noise performance, it is recommended that the ADP2164 and ADP2370 switching regulators be used to convert the 3.3 V, 5.0 V, or 12 V input rails to an intermediate rail (1.8 V and 3.8 V). These intermediate rails are then postregulated by very low noise, low dropout (LDO) regulators (ADP1741, ADM7172, and ADP125). Figure 174 shows the recommended power supply scheme for the AD9680. ADP1741 1.8V AVDD1 1.25V plane must have several vias to achieve the lowest possible resistive thermal path for heat dissipation to flow through the bottom of the PCB. These vias must be solder filled or plugged. The number of vias and the fill determine the resulting θJA measured on the board. To maximize the coverage and adhesion between the ADC and PCB, partition the continuous copper plane by overlaying a silkscreen on the PCB into several uniform sections. This provides several tie points between the ADC and PCB during the reflow process, whereas using one continuous plane with no partitions only guarantees one tie point. See Figure 175 for a PCB layout example. For detailed information on packaging and the PCB layout of chip scale packages, see the AN-772 Application Note, A Design and Manufacturing Guide for the Lead Frame Chip Scale Package (LFCSP). AVDD1_SR 1.25V ADP1741 DVDD 1.25V DRVDD 1.25V 3.6V ADP125 AVDD3 3.3V 3.3V ADM7172 OR ADP1741 AVDD2 2.5V 11752-063 SPIVDD (1.8V OR 3.3V) It is not necessary to split all of these power domains in all cases. The recommended solution shown in Figure 174 provides the lowest noise, highest efficiency power delivery system for the AD9680. If only one 1.25 V supply is available, route to AVDD1 first and then tap it off and isolate it with a ferrite bead or a filter choke, preceded by decoupling capacitors for AVDD1_SR, DVDD, and DRVDD, in that order. This is shown as the optional path in Figure 174. The user can employ several different decoupling capacitors to cover both high and low frequencies. These capacitors must be located close to the point of entry at the PCB level and close to the devices, with minimal trace lengths. EXPOSED PAD THERMAL HEAT SLUG RECOMMENDATIONS The exposed pad on the underside of the ADC must be connected to AGND to achieve the best electrical and thermal performance of the AD9680. Connect an exposed continuous copper plane on the PCB to the AD9680 exposed pad, Pin 0. The copper 11752-064 Figure 174. High Efficiency, Low Noise Power Solution for the AD9680 Figure 175. Recommended PCB Layout of Exposed Pad for the AD9680 AVDD1_SR (PIN 57) AND AGND (PIN 56 AND PIN 60) AVDD1_SR (Pin 57) and AGND (Pin 56 and Pin 60) can be used to provide a separate power supply node to the SYSREF± circuits of AD9680. If running in Subclass 1, the AD9680 can support periodic one-shot or gapped signals. To minimize the coupling of this supply into the AVDD1 supply node, adequate supply bypassing is needed. Rev. C | Page 96 of 97 Online Documentation Product Overview Design Resources Discussion Sample & Buy Data Sheet AD9680 OUTLINE DIMENSIONS 9.10 9.00 SQ 8.90 0.30 0.25 0.18 PIN 1 INDICATOR 49 1 0.50 BSC EXPOSED PAD 7.70 7.60 SQ 7.50 33 0.80 0.75 0.70 0.45 0.40 0.35 16 32 17 BOTTOM VIEW 7.50 REF 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.203 REF PKG-004396 SEATING PLANE 0.20 MIN FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. COMPLIANT TO JEDEC STANDARDS MO-220-WMMD 02-12-2014-A TOP VIEW PIN 1 INDICATOR 64 48 Figure 176. 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 9 mm × 9 mm Body, Very Thin Quad (CP-64-15) Dimensions shown in millimeters ORDERING GUIDE Model1 AD9680BCPZ-1250 AD9680BCPZ-1000 AD9680BCPZ-820 AD9680BCPZ-500 AD9680BCPZRL7-1250 AD9680BCPZRL7-1000 AD9680BCPZRL7-820 AD9680BCPZRL7-500 AD9680-1250EBZ AD9680-1000EBZ AD9680-LF1000EBZ AD9680-820EBZ AD9680-LF820EBZ AD9680-500EBZ AD9680-LF500EBZ 1 2 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Package Description2 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_WQ] Evaluation Board for AD9680-1250 Evaluation Board for AD9680-1000 Evaluation Board for AD9680-1000 with 1 GHz Bandwidth Evaluation Board for AD9680-820 Evaluation Board for AD9680-820 with 1 GHz Bandwidth Evaluation Board for AD9680-500 Evaluation Board for AD9680-500 with 1 GHz Bandwidth Package Option CP-64-15 CP-64-15 CP-64-15 CP-64-15 CP-64-15 CP-64-15 CP-64-15 CP-64-15 Z = RoHS Compliant Part. The AD9680-1250EBZ, AD9680-1000EBZ, AD9680-820EBA, and AD9680-500EBZ evaluation boards are optimized for full analog input frequency range of 2 GHz. ©2014–2015 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D11752-0-11/15(C) Rev. C | Page 97 of 97