14-Bit, 80 MSPS/155 MSPS, 1.8 V Dual Serial Output Analog-to-Digital Converter (ADC) AD9644 Data Sheet FUNCTIONAL BLOCK DIAGRAM AVDD AGND DRVDD AD9644 VIN+A VIN–A PIPELINE 14-BIT ADC 14 VCMA VIN+B VIN–B PIPELINE 14-BIT ADC 14 VCMB REFERENCE PDWN SERIAL PORT (SPI) SCLK SDIO CSB DRGND DOUT+A DOUT–A DSYNC+A DSYNC–A DOUT+B DOUT–B DSYNC+B DSYNC–B PLL 1 TO 8 CLOCK DIVIDER CLK+ CLK– SYNC 09180-001 JESD204A coded serial digital outputs SNR = 73.7 dBFS at 70 MHz and 80 MSPS SNR = 71.7 dBFS at 70 MHz and 155 MSPS SFDR = 92 dBc at 70 MHz and 80 MSPS SFDR = 92 dBc at 70 MHz and 155 MSPS Low power: 423 mW at 80 MSPS, 567 mW at 155 MSPS 1.8 V supply operation Integer 1-to-8 input clock divider IF sampling frequencies to 250 MHz −148.6 dBFS/Hz input noise at 180 MHz and 80 MSPS −150.3 dBFS/Hz input noise at 180 MHz and 155 MSPS Programmable internal ADC voltage reference Flexible analog input range: 1.4 V p-p to 2.1 V p-p ADC clock duty cycle stabilizer Serial port control User-configurable, built-in self-test (BIST) capability Energy-saving power-down modes JESD204A 8-BIT/10-BIT CODING, SERIALIZER AND CML DRIVERS FEATURES Figure 1. 48-Lead 7 mm × 7 mm LFCSP APPLICATIONS Communications Diversity radio systems Multimode digital receivers (3G and 4G) GSM, EDGE, W-CDMA, LTE, CDMA2000, WiMAX, TD-SCDMA I/Q demodulation systems Smart antenna systems General-purpose software radios Broadband data applications Ultrasound equipment PRODUCT HIGHLIGHTS 1. 2. 3. 4. 5. An on-chip PLL allows users to provide a single ADC sampling clock; the PLL multiplies the ADC sampling clock to produce the corresponding JESD204A data rate clock. The configurable JESD204A output block supports up to 1.6 Gbps per channel data rate when using a dedicated data link per ADC or 3.2 Gbps data rate when using a single shared data link for both ADCs. Proprietary differential input that maintains excellent SNR performance for input frequencies up to 250 MHz. Operation from a single 1.8 V power supply. Standard serial port interface (SPI) that supports various product features and functions, such as data formatting (offset binary, twos complement, or gray coding), controlling the clock DCS, power-down, test modes, voltage reference mode, and serial output configuration. 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 ©2010–2012 Analog Devices, Inc. All rights reserved. AD9644 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Voltage Reference ....................................................................... 22 Applications ....................................................................................... 1 Clock Input Considerations ...................................................... 22 Functional Block Diagram .............................................................. 1 Channel/Chip Synchronization ................................................ 24 Product Highlights ........................................................................... 1 Power Dissipation and Standby Mode .................................... 24 Revision History ............................................................................... 2 Digital Outputs ........................................................................... 24 General Description ......................................................................... 3 Built-In Self-Test (BIST) and Output Test .................................. 29 Specifications..................................................................................... 4 Built-In Self-Test (BIST) ............................................................ 29 ADC DC Specifications ............................................................... 4 Output Test Modes ..................................................................... 29 ADC AC Specifications ............................................................... 5 Serial Port Interface (SPI) .............................................................. 31 Digital Specifications ................................................................... 6 Configuration Using the SPI ..................................................... 31 Switching Specifications .............................................................. 8 Hardware Interface..................................................................... 32 Timing Specifications .................................................................. 9 SPI Accessible Features .............................................................. 32 Absolute Maximum Ratings.......................................................... 10 Memory Map .................................................................................. 33 Thermal Characteristics ................................................................ 10 Reading the Memory Map Register Table............................... 33 ESD Caution ................................................................................ 10 Memory Map Register Table ..................................................... 34 Pin Configuration and Function Descriptions ........................... 11 Memory Map Register Descriptions ........................................ 38 Typical Performance Characteristics ........................................... 13 Applications Information .............................................................. 42 Equivalent Circuits ......................................................................... 19 Design Guidelines ...................................................................... 42 Theory of Operation ...................................................................... 20 Outline Dimensions ....................................................................... 43 ADC Architecture ...................................................................... 20 Ordering Guide .......................................................................... 43 Analog Input Considerations.................................................... 20 REVISION HISTORY 1/12—Rev. B to Rev. C Change to General Description Section ........................................ 3 6/11—Rev. A to Rev. B Added Figure 23 to Figure 40; Renumbered Sequentially ........ 16 Changes to Clock Input Considerations Section........................ 22 Added Figure 61.............................................................................. 24 Changes to Digital Outputs and Timing Section ....................... 27 Added Figure 69.............................................................................. 28 Changes to Output Test Modes Section ...................................... 29 Changes to SPI Accessible Features Section ............................... 32 4/11—Rev. 0 to Rev. A Added Model -155 ......................................................... Throughout Changes to Features Section and Figure 1 .....................................1 Changes to General Description Section .......................................3 Changes to Table 1.............................................................................4 Changes to Table 2.............................................................................5 Changes to Table 4.............................................................................8 Additions to TPC Introductory Statement ................................. 13 Changes to Speed Grade ID Bits in Table 17 .............................. 31 Changes to Ordering Guide .......................................................... 40 6/10—Revision 0: Initial Version Rev. C | Page 2 of 44 Data Sheet AD9644 GENERAL DESCRIPTION The AD9644 is a dual, 14-bit, analog-to-digital converter (ADC) with a high speed serial output interface and sampling speeds of either 80 MSPS or 155 MSPS. The AD9644 is designed to support communications applications where high performance, combined with low cost, small size, and versatility, is desired. The JESD204A high speed serial interface reduces board routing requirements and lowers pin count requirements for the receiving device. The dual ADC core features a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC features wide bandwidth differential sample-and-hold analog input amplifiers that support a variety of user-selectable input ranges. An integrated voltage reference eases design considerations. A duty cycle stabilizer is provided to compensate for variations in the ADC clock duty cycle, allowing the converters to maintain excellent performance. By default, the ADC output data is routed directly to the two external JESD204A serial output ports. These outputs are at CML voltage levels. Two modes are supported such that output coded data is either sent through one data link or two. (L = 1; F = 4 or L = 2; F = 2). Independent synchronization inputs (DSYNC) are provided for each channel. Flexible power-down options allow significant power savings, when desired. Programming for setup and control is accomplished using a 3-wire SPI-compatible serial interface. The AD9644 is available in a 48-lead LFCSP and is specified over the industrial temperature range of −40°C to +85°C. This product is protected by a U.S. patent. Rev. C | Page 3 of 44 AD9644 Data Sheet SPECIFICATIONS ADC DC SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, 1.75 V p-p differential input, VIN = −1.0 dBFS differential input, DCS enabled, unless otherwise noted. Table 1. Parameter RESOLUTION ACCURACY No Missing Codes Offset Error Gain Error Differential Nonlinearity (DNL) 1 Integral Nonlinearity (INL)1 MATCHING CHARACTERISTIC Offset Error Gain Error TEMPERATURE DRIFT Offset Error Gain Error INPUT REFERRED NOISE ANALOG INPUT Input Span Input Capacitance 2 Input Resistance VCM OUTPUT LEVEL POWER SUPPLIES Supply Voltage AVDD DRVDD Supply Current IAVDD1 IDRVDD1 POWER CONSUMPTION Sine Wave Input1 Standby Power 3 Power-Down Power Temperature Full Full Full Full Full 25°C Full 25°C Full Full Min 14 −7 AD9644-80 Typ Max Guaranteed ±2 −2.5 ±10 +1 ±0.55 Min 14 −6 ±0.3 AD9644-155 Typ Max Guaranteed ±2.2 −1.5 ±0.3 ±1.1 ±1.25 ±0.5 −7 −1.5 Full Full 25°C +1.5 +0.6 ±0.55 +10 +2.75 −6 −3.1 ±2 ±35 0.7 Full Full Full Full 1.383 Full Full 2.087 1.383 0.88 0.92 1.7 1.7 1.8 1.8 1.9 1.9 Full Full 175 60 Full Full Full 423 85 15 Rev. C | Page 4 of 44 +9 +5 mV % FSR LSB LSB LSB LSB mV % FSR ppm/°C ppm/°C LSB rms 2.087 0.87 1.75 5 20 0.9 0.93 V p-p pF kΩ V 1.7 1.7 1.8 1.8 1.9 1.9 V V 190 67 226 89 242 97 mA mA 460 567 168 18 610 mW mW mW 27 Measured with a low input frequency, full-scale sine wave. Input capacitance refers to the effective capacitance between one differential input pin and AGND. 3 Standby power is measured with a dc input and with the CLK pins inactive (set to AVDD or AGND). 2 +1.5 +0.75 ±2 ±144 0.7 1.75 7 20 0.9 1 ±11 +4 ±0.55 Unit Bits 27 Data Sheet AD9644 ADC AC SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, 1.75 V p-p differential input, VIN = −1.0 dBFS differential input, DCS enabled, unless otherwise noted. Table 2. Parameter 1 SIGNAL-TO-NOISE-RATIO (SNR) fIN = 10 MHz fIN = 70 MHz fIN = 180 MHz AD9644BCPZ-80 AD9644CCPZ-80 AD9644BCPZ-155 fIN = 220 MHz SIGNAL-TO-NOISE AND DISTORTION (SINAD) fIN = 10 MHz fIN = 70 MHz fIN = 180 MHz AD9644BCPZ-80 AD9644CCPZ-80 AD9644BCPZ-155 fIN = 220 MHz EFFECTIVE NUMBER OF BITS (ENOB) fIN = 10 MHz fIN = 70 MHz fIN = 180 MHz fIN = 220 MHz WORST SECOND OR THIRD HARMONIC fIN = 10 MHz fIN = 70 MHz fIN = 180 MHz AD9644BCPZ-80 AD9644CCPZ-80 AD9644BCPZ-155 fIN = 220 MHz SPURIOUS-FREE DYNAMIC RANGE (SFDR) fIN = 10 MHz fIN = 70 MHz fIN = 180 MHz AD9644BCPZ-80 AD9644CCPZ-80 AD9644BCPZ-155 fIN = 220 MHz WORST OTHER (HARMONIC OR SPUR) fIN = 10 MHz fIN = 70 MHz fIN = 180 MHz AD9644BCPZ-80 AD9644CCPZ-80 AD9644BCPZ-155 fIN = 220 MHz Temperature 25°C 25°C 25°C Full Full Full 25°C 25°C 25°C 25°C Full Full Full 25°C Min AD9644-80 Typ Max Min 73.8 73.7 72.6 AD9644-155 Typ Max 71.9 71.7 71.4 dBFS dBFS dBFS dBFS dBFS dBFS dBFS 71.8 70.0 69.8 72.0 71.0 72.7 72.6 71.5 70.8 70.7 70.3 Unit 71.1 69.9 dBFS dBFS dBFS dBFS dBFS dBFS dBFS 25°C 25°C 25°C 25°C 11.8 11.8 11.6 11.5 11.5 11.5 11.4 11.3 Bits Bits Bits Bits 25°C 25°C 25°C Full Full Full 25°C −94 −92 −87 −94 −92 −92 −85 −90 dBc dBc dBc dBc dBc dBc dBc 25°C 25°C 25°C Full Full Full 25°C 94 92 87 94 92 92 25°C 25°C 25°C Full Full Full 25°C Rev. C | Page 5 of 44 70.4 68.6 68.7 −80 −73 −80 dBc dBc dBc dBc dBc dBc dBc 80 73 80 85 90 −98 −98 −96 −97 −97 −95 −90 −87 −89 −95 −94 dBc dBc dBc dBc dBc dBc dBc AD9644 Parameter 1 TWO-TONE SFDR fIN = +30 MHz (−7 dBFS ), +33 MHz (−7 dBFS ) fIN = +169 MHz (−7 dBFS ), +172 MHz (−7 dBFS ) CROSSTALK 2 ANALOG INPUT BANDWIDTH 3 Data Sheet Temperature Min AD9644-80 Typ Max 25°C 25°C Full 25°C Min 93 89 −105 780 AD9644-155 Typ Max 90 89 −105 780 Unit dBc dBc dB MHz See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions. Crosstalk is measured at 100 MHz with −1.0 dBFS on one channel and no input on the alternate channel. 3 Analog input bandwidth specifies the −3 dB input BW of the AD9644 input. The usable full-scale BW of the part with good performance is 250 MHz. 1 2 DIGITAL SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, 1.75 V p-p differential input, VIN = −1.0 dBFS differential input, and DCS enabled, unless otherwise noted. Table 3. Parameter DIFFERENTIAL CLOCK INPUTS (CLK+, CLK−) Logic Compliance Internal Common-Mode Bias Differential Input Voltage Input Voltage Range Input Common-Mode Range High Level Input Current Low Level Input Current Input Capacitance Input Resistance SYNC INPUT Logic Compliance Internal Bias Input Voltage Range High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Capacitance Input Resistance DSYNC INPUT Logic Compliance Internal Bias Input Voltage Range High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Capacitance Input Resistance 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 Rev. C | Page 6 of 44 Min AD9644-80/AD9644-155 Typ Max CMOS/LVDS/LVPECL 0.9 0.3 AGND 0.9 −100 −100 8 3.6 AVDD 1.4 +100 +100 4 10 12 CMOS 0.9 AGND 1.2 AGND −100 −100 12 AVDD AVDD 0.6 +100 +100 1 16 20 CMOS/LVDS 0.9 AGND 1.2 AGND −100 −100 12 AVDD AVDD 0.6 +100 +100 1 16 20 Unit V V p-p V V µA µA pF kΩ V V V V µA µA pF kΩ V V V V µA µA pF kΩ Data Sheet Parameter LOGIC INPUT (CSB) 1 Logic Compliance High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUT (SCLK, PDWN) 2 Logic Compliance High Level Input Voltage Low Level Input Voltage High Level Input Current (VIN = 1.8 V) Low Level Input Current Input Resistance Input Capacitance LOGIC INPUT/OUTPUT (SDIO)1 Logic Compliance High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance DIGITAL OUTPUTS Logic Compliance Differential Output Voltage (VOD) Output Offset Voltage (VOS) 1 2 AD9644 Temperature Min Full Full Full Full Full Full 1.22 0 −10 40 Full Full Full Full Full Full 1.22 0 −92 −10 Full Full Full Full Full Full 1.22 0 −10 38 AD9644-80/AD9644-155 Typ Max Unit CMOS 2.1 0.6 +10 132 V V µA µA kΩ pF 2.1 0.6 −135 +10 V V µA µA kΩ pF 2.1 0.6 +10 128 V V µA µA kΩ pF 1.1 1.05 V V 26 2 CMOS 26 2 CMOS Full Full Full Pull up. Pull down. Rev. C | Page 7 of 44 26 5 0.6 0.75 CML 0.8 DRVDD/2 AD9644 Data Sheet SWITCHING SPECIFICATIONS AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, 1.75 V p-p differential input, VIN = −1.0 dBFS differential input, and DCS enabled, unless otherwise noted. Table 4. Parameter CLOCK INPUT PARAMETERS Input Clock Rate Conversion Rate 1 CLK Period—Divide-by-1 Mode (tCLK) CLK Pulse Width High (tCH) Divide-by-1 Mode, DCS Enabled Divide-by-1 Mode, DCS Disabled Divide-by-2 Mode Through Divide-by-8 Mode Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) DATA OUTPUT PARAMETERS Data Output Period or UI (Unit Interval) Data Output Duty Cycle Data Valid Time PLL Lock Time (tLOCK) Wake Up Time (Standby) Wake Up Time (Power-Down) 2 Pipeline Delay (Latency) Data Rate per Channel (NRZ) Deterministic Jitter Random Jitter at 1.6 Gbps Random Jitter at 3.2 Gbps Output Rise/Fall Time TERMINATION CHARACTERISTICS Differential Termination Resistance OUT-OF-RANGE RECOVERY TIME 1 2 Temperature Min Full Full Full 40 12.5 Full Full Full 3.75 5.95 0.8 AD9644-80 Typ Max 640 80 6.25 6.25 8.75 6.55 Min AD9644-155 Typ 40 6.45 1.935 3.065 0.8 3.225 3.225 Max Unit 640 155 MHz MSPS ns 4.515 3.385 ns ns ns Full Full 0.78 0.125 0.78 0.125 ns ps rms Full 25°C 25°C 25°C 25°C 25°C Full 1/(20 × fCLK) 1/(20 × fCLK) 50 0.74 4 5 2.5 Seconds % UI µs µs ms CLK cycles Gbps ps ps rms ps rms ps 50 0.78 4 5 2.5 23 24 23 24 25°C 25°C 25°C 25°C 25°C 1.6 40 9.5 5.2 50 5.2 50 25°C 25°C 100 2 100 2 Conversion rate is the clock rate after the divider. Wake-up time is defined as the time required to return to normal operation from power-down mode. Rev. C | Page 8 of 44 3.1 40 Ω CLK cycles Data Sheet AD9644 TIMING SPECIFICATIONS Table 5. Parameter SYNC TIMING REQUIREMENTS tSSYNC tHSYNC SPI TIMING REQUIREMENTS tDS tDH tCLK tS tH tHIGH tLOW tEN_SDIO tDIS_SDIO Conditions Limit SYNC to rising edge of CLK+ setup time SYNC to rising edge of CLK+ hold time 0.30 ns typ 0.30 ns typ 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 SCLK pulse width high SCLK pulse width low Time required for the SDIO pin to switch from an input to an output relative to the SCLK falling edge Time required for the SDIO pin to switch from an output to an input relative to the SCLK rising edge 2 ns min 2 ns min 40 ns min 2 ns min 2 ns min 10 ns min 10 ns min 10 ns min 10 ns min Timing Diagrams SAMPLE N N – 23 ANALOG INPUT SIGNAL N – 22 N+1 N – 21 N–1 N – 20 CLK– CLK+ CLK– CLK+ DOUT+ SAMPLE N – 23 ENCODED INTO 2 8b/10b SYMBOLS SAMPLE N – 22 ENCODED INTO 2 8b/10b SYMBOLS SAMPLE N – 21 ENCODED INTO 2 8b/10b SYMBOLS Figure 2. Data Output Timing CLK+ tHSYNC 09180-004 tSSYNC SYNC Figure 3. SYNC Input Timing Requirements Rev. C | Page 9 of 44 09180-002 DOUT– AD9644 Data Sheet ABSOLUTE MAXIMUM RATINGS THERMAL CHARACTERISTICS Table 6. Parameter ELECTRICAL AVDD to AGND DRVDD to AGND VIN+A/VIN+B, VIN−A/VIN−B to AGND CLK+, CLK− to AGND SYNC to AGND VCMA, VCMB to AGND CSB to AGND SCLK to AGND SDIO to AGND PDWN to AGND DOUT+A, DOUT0−A, DOUT0+B, DOUT−B to AGND DSYNC+A, DSYNC−A, DSYNC+B, DSYNC−B to AGND ENVIRONMENTAL Operating Temperature Range (Ambient) Maximum Junction Temperature Under Bias Storage Temperature Range (Ambient) Rating −0.3 V to +2.0 V −0.3 V to +2.0V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to AVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V −0.3 V to DRVDD + 0.2 V The exposed paddle must be soldered to the ground plane for the LFCSP package. Soldering the exposed paddle to the PCB increases the reliability of the solder joints and maximizes the thermal capability of the package. Table 7. Thermal Resistance Package Type 48-Lead LFCSP 7 mm × 7 mm (CP-48-8) Airflow Velocity (m/sec) 0 1.0 2.5 θJA1, 2 25 22 20 θJC1, 3 2 θJB1, 4 14 Unit °C/W °C/W °C/W Per JEDEC 51-7, plus JEDEC 25-5 2S2P test board. Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air). 3 Per MIL-STD 883, Method 1012.1. 4 Per JEDEC JESD51-8 (still air). 1 2 Typical θJA is specified for a 4-layer PCB with a solid ground plane. As shown Table 7, airflow improves heat dissipation, which reduces θJA. In addition, metal in direct contact with the package leads from metal traces, through holes, ground, and power planes, reduces θJA. −40°C to +85°C 150°C −65°C to +150°C ESD CAUTION Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. C | Page 10 of 44 Data Sheet AD9644 48 47 46 45 44 43 42 41 40 39 38 37 AVDD AVDD VIN–B VIN+B AVDD AVDD AVDD AVDD VIN+A VIN–A AVDD AVDD PIN CONFIGURATION AND FUNCTION DESCRIPTIONS AD9644 TOP VIEW (Not to Scale) 36 35 34 33 32 31 30 29 28 27 26 25 VCMA DNC DNC PDWN DNC CSB SCLK SDIO DRVDD DRVDD DRGND DNC NOTES 1. DNC = DO NOT CONNECT. 2. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART. THIS EXPOSED PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION. 09180-104 DSYNC–B DSYNC+B DRVDD DRGND DOUT–B DOUT+B DOUT–A DOUT+A DRGND DRVDD DSYNC–A DSYNC+A 13 14 15 16 17 18 19 20 21 22 23 24 VCMB 1 AVDD 2 DNC 3 AVDD 4 CLK+ 5 CLK– 6 AVDD 7 SYNC 8 AVDD 9 DRGND 10 DRVDD 11 DNC 12 Figure 4. LFCSP Pin Configuration (Top View) Table 8. Pin Function Descriptions Pin No. ADC Power Supplies 11, 15, 22, 27, 28 2, 4, 7, 9, 37, 38, 41, 42, 43, 44, 47, 48 3, 12, 25, 32, 34, 35 10, 16, 21, 26 0 ADC Analog 40 39 45 46 36 1 5 6 Digital Input 8 24 Mnemonic Type Description DRVDD AVDD Supply Supply Digital Output Driver Supply (1.8 V Nominal). Analog Power Supply (1.8 V Nominal). DNC DRGND AGND, Exposed Pad Driver Ground Ground Do Not Connect. Digital Driver Supply Ground. The exposed thermal pad on the bottom of the package provides the analog ground for the part. This exposed pad must be connected to ground for proper operation. VIN+A VIN−A VIN+B VIN−B VCMA VCMB CLK+ CLK− Input Input Input Input Output Output Input Input Differential Analog Input Pin (+) for Channel A. Differential Analog Input Pin (−) for Channel A. Differential Analog Input Pin (+) for Channel B. Differential Analog Input Pin (−) for Channel B. Common-Mode Level Bias Output for Channel A Analog Input. Common-Mode Level Bias Output for Channel B Analog Input. ADC Clock Input—True. ADC Clock Input—Complement. SYNC DSYNC+A Input Input 23 14 DSYNC−A DSYNC+B Input Input 13 DSYNC−B Input Input Clock Divider Synchronization Pin. Active Low JESD204A LVDS Channel A SYNC Input—True/JESD204A CMOS Channel A SYNC Input. Active Low JESD204A LVDS Channel A SYNC Input—Complement. Active Low JESD204A LVDS Channel B SYNC Input—True/JESD204A CMOS Channel A SYNC Input. Active Low JESD204A LVDS Channel B SYNC Input—Complement. Rev. C | Page 11 of 44 AD9644 Pin No. Digital Outputs 20 19 18 17 SPI Control 30 29 31 ADC Configuration 33 Data Sheet Mnemonic Type Description DOUT+A DOUT−A DOUT+B DOUT−B Output Output Output Output Channel A CML Output Data—True. Channel A CML Output Data—Complement. Channel B CML Output Data—True. Channel B CML Output Data—Complement. SCLK SDIO CSB Input Input/Output Input SPI Serial Clock. SPI Serial Data Input/Output. SPI Chip Select (Active Low). PDWN Input Power-Down Input. Using the SPI interface, this input can be configured as power-down or standby. Rev. C | Page 12 of 44 Data Sheet AD9644 TYPICAL PERFORMANCE CHARACTERISTICS AVDD = 1.8 V, DRVDD = 1.8 V, DCS enabled, 1.75 V p-p differential input, VIN = −1.0 dBFS, and 32k sample, TA = 25°C, unless otherwise noted. 0 0 –20 –80 THIRD HARMONIC –100 –120 –120 10 20 30 40 –140 09180-005 0 FREQUENCY (MHz) 0 10 20 30 Figure 8. AD9644-80 Single-Tone FFT with fIN = 140.1 MHz 0 0 80MSPS 30.1MHz @ –1dBFS SNR = 72.7dB (73.7dBFS) SFDR = 94dBc AMPLITUDE (dBFS) –60 SECOND HARMONIC –80 THIRD HARMONIC –40 –60 SECOND HARMONIC –80 –100 –100 –120 –120 0 10 20 30 40 FREQUENCY (MHz) –140 09180-106 –140 80MSPS 180.1MHz @ –1dBFS SNR = 71.6dB (72.6dBFS) SFDR = 93dBc –20 –40 0 10 20 30 Figure 9. AD9644-80 Single-Tone FFT with fIN = 180.1 MHz 0 0 80MSPS 70.1MHz @ –1dBFS SNR = 72.5dB (73.5dBFS) SFDR = 94.0dBc AMPLITUDE (dBFS) –60 SECOND HARMONIC –80 THIRD HARMONIC –40 –60 THIRD HARMONIC –80 SECOND HARMONIC –100 –100 –120 –120 –140 0 10 20 30 FREQUENCY (MHz) 80MSPS 220.1MHz @ –1dBFS SNR = 71.1dB (72.1dBFS) SFDR = 92dBc –20 –40 40 40 FREQUENCY (MHz) Figure 6. AD9644-80 Single-Tone FFT with fIN = 30.1 MHz –20 40 FREQUENCY (MHz) Figure 5. AD9644-80 Single-Tone FFT with fIN = 10.1 MHz –20 AMPLITUDE (dBFS) –80 –100 –140 AMPLITUDE (dBFS) –60 Figure 7. AD9644-80 Single-Tone FFT with fIN = 70.1 MHz –140 0 10 20 30 FREQUENCY (MHz) Figure 10. AD9644-80 Single-Tone FFT with fIN = 220.1 MHz Rev. C | Page 13 of 44 09180-108 –60 –40 09180-109 AMPLITUDE (dBFS) –40 09180-107 AMPLITUDE (dBFS) –20 80MSPS 140.3MHz @ –1dBFS SNR = 72.2dB (73.2dBFS) SFDR = 94.0dBc 40 09180-110 80MSPS 10.1MHz @ –1dBFS SNR = 73.0dB (74.0dBFS) SFDR = 95dBc AD9644 Data Sheet 100 120 95 SNR/SFDR (dBFS/dBc) 80 SFDR (dBFS) SFDR (dBc) SNR (dBFS) SNR (dBc) 60 40 20 80 75 Figure 11. AD9644-80 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 10.1 MHz, fS = 80 MSPS –20 SFDR/IMD3 (dBc/dBFS) 100 SFDR (dBFS) SFDR (dBc) SNR (dBFS) SNR (dBc) 40 150 200 250 Figure 14. AD9644-80 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and Temperature with 2.0 V p-p Full-Scale, fS = 80 MSPS 0 60 100 INPUT FREQUENCY (MHz) 120 80 50 09180-114 0 09180-111 –100 –95 –90 –85 –80 –75 –70 –65 –60 –55 –50 –45 –40 –35 –30 –25 –20 –15 –10 –5 0 65 INPUT AMPLITUDE (dBFS) –40 –60 –80 SFDR (dBc) IMD3 (dBc) SFDR (dBFS) IMD3 (dBFS) –100 20 –120 –90 INPUT AMPLITUDE (dBFS) 09180-112 –100 –95 –90 –85 –80 –75 –70 –65 –60 –55 –50 –45 –40 –35 –30 –25 –20 –15 –10 –5 0 0 Figure 12. AD9644-80 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 180 MHz, fS = 80 MSPS –78 –66 –54 –42 –30 –18 –6 INPUT AMPLITUDE (dBFS) 09180-015 SNR/SFDR (dBc/dBFS) SNR @ –40°C SFDR @ –40°C SNR @ +25°C SFDR @ +25°C SNR @ +85°C SFDR @ +85°C 85 70 0 Figure 15. AD9644-80 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 29.9 MHz, fIN2 = 32.9 MHz, fS = 80 MSPS 100 0 95 –20 90 SFDR/IMD3 (dBc/dBFS) SNR/SFDR (dBFS/dBc) 90 SNR @ –40°C SFDR @ –40°C SNR @ +25°C SFDR @ +25°C SNR @ +85°C SFDR @ +85°C 85 80 75 –40 –60 –80 SFDR (dBc) IMD3 (dBc) SFDR (dBFS) IMD3 (dBFS) –100 70 0 50 100 150 INPUT FREQUENCY (MHz) 200 250 –120 –90 09180-113 65 Figure 13. AD9644-80 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and Temperature with 1.75 V p-p Full-Scale, fS = 80 MSPS –78 –66 –54 –42 –30 INPUT AMPLITUDE (dBFS) –18 –6 09180-116 SNR/SFDR (dBc/dBFS) 100 Figure 16. AD9644-80 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 169.1 MHz, fIN2 = 172.1 MHz, fS = 80 MSPS Rev. C | Page 14 of 44 Data Sheet AD9644 0 14,000 80MSPS 29.9MHz @ –7dBFS 32.9MHz @ –7dBFS SFDR = 94.4dBc (101.4dBFS) 12,000 –40 NUMBER OF HITS 10,000 –80 8000 6000 –100 4000 –120 2000 –140 0 10 20 30 40 FREQUENCY (MHz) 0 N–4 N–3 N–2 N–1 Figure 17. AD9644-80 Two-Tone FFT with fIN1 = 29.9 MHz and fIN2 = 32.9 MHz N+1 N+2 N+3 N+4 Figure 20. AD9644-80 Grounded Input Histogram 0 1.0 80MSPS 169.1MHz @ –7dBFS 172.1MHz @ –7dBFS SFDR = 91.9dBc (98.9dBFS) –20 0.8 0.6 –40 0.4 INL ERROR (LSB) AMPLITUDE (dBFS) N OUTPUT CODE 09180-020 –60 09180-117 AMPLITUDE (dBFS) –20 –60 –80 0.2 0 –0.2 –0.4 –100 –0.6 –120 10 20 30 40 FREQUENCY (MHz) –1.0 09180-118 0 0 200 400 600 800 1000 1200 1400 1600 OUTPUT CODE Figure 18. AD9644-80 Two-Tone FFT with fIN1 = 169.1 MHz and fIN2 = 172.1 MHz 09180-121 –0.8 –140 Figure 21. AD9644-80 INL with fIN = 30.3 MHz 100 0.50 0.25 DNL ERROR (LSB) 90 SNR CHANNEL B SFDR CHANNEL B SNR CHANNEL A SFDR CHANNEL A 85 80 0 –0.25 70 45 50 55 60 65 70 75 80 SAMPLE RATE (MSPS) Figure 19. AD9644-80 Single-Tone SNR/SFDR vs. Sample Rate (fS) with fIN = 70. MHz –0.50 0 2000 4000 6000 8000 10,000 12,000 14,000 16,000 OUTPUT CODE Figure 22. AD9644-80 DNL with fIN = 30.3 MHz Rev. C | Page 15 of 44 09180-122 75 09180-119 SNR/SFDR (dBFS/dBc) 95 AD9644 Data Sheet 0 0 155MSPS 10.1MHz @ –1dBFS SNR = 70.9dB (71.9dBFS) SFDR = 94dBc –20 –40 AMPLITUDE (dBFS) –60 THIRD HARMONIC –80 –100 –100 –120 0 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) –140 09180-123 –140 0 Figure 23. AD9644-155 Single-Tone FFT with fIN = 10.1 MHz 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) Figure 26. AD9644-155 Single-Tone FFT with fIN = 140.1 MHz 0 0 155MSPS 30.1MHz @ –1dBFS SNR = 70.8dB (71.8dBFS) SFDR = 93dBc –20 155MSPS 180.1MHz @ –1dBFS SNR = 70.4dB (71.4dBFS) SFDR = 92dBc –20 –40 –40 –60 SECOND HARMONIC –80 AMPLITUDE (dBFS) THIRD HARMONIC –100 –120 –60 THIRD HARMONIC –80 –100 –120 0 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) –140 09180-124 –140 0 Figure 24. AD9644-155 Single-Tone FFT with fIN = 30.1 MHz 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) 09180-127 AMPLITUDE (dBFS) THIRD HARMONIC –80 09180-126 –120 SECOND HARMONIC –60 Figure 27. AD9644-155 Single-Tone FFT with fIN = 180.1 MHz 0 0 155MSPS 70.1MHz @ –1dBFS SNR = 70.7dB (71.7dBFS) SFDR = 92dBc –20 155MSPS 220.1MHz @ –1dBFS SNR = 70.0dB (71.0dBFS) SFDR = 90dBc –20 –40 AMPLITUDE (dBFS) –40 –60 –80 –100 THIRD HARMONIC –80 –100 –120 –140 0 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) 09180-125 –120 –60 Figure 25. AD9644-155 Single-Tone FFT with fIN = 70.1 MHz –140 0 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) Figure 28. AD9644-155 Single-Tone FFT with fIN = 220.1 MHz Rev. C | Page 16 of 44 09180-128 AMPLITUDE (dBFS) –40 AMPLITUDE (dBFS) 155MSPS 140.1MHz @ –1dBFS SNR = 70.5dB (71.5dBFS) SFDR = 92dBc –20 Data Sheet AD9644 100 120 SNR @ –40°C SFDR @ –40°C SNR @ +25°C SFDR @ +25°C SNR @ +85°C SFDR @ +85°C SFDR (dBFS) 95 80 SNR/SFDR (dBFS/dBc) SNR (dBFS) 60 SFDR (dBc) 40 SNR (dBc) 20 85 80 75 70 –80 –70 –60 –50 –40 –30 INPUT AMPLITUDE (dBFS) –20 –10 0 65 09180-129 0 –90 90 0 Figure 29. AD9644-155 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 10.1 MHz, fS = 80 MSPS 50 100 150 200 INPUT FREQUENCY (MHz) 250 300 09180-132 SNR/SFDR (dBc AND dBFS) 100 Figure 32. AD9644-155 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and Temperature with 2.0 V p-p Full-Scale, fS = 80 MSPS 120 0 SFDR (dBFS) –20 80 SFDR/IMD3 (dBc AND dBFS) SNR/SFDR (dBc AND dBFS) 100 SNR (dBFS) 60 SFDR (dBc) 40 SNR (dBc) 20 –40 SFDR (dBc) –60 IMD3 (dBc) –80 –100 SFDR (dBFS) –70 –60 –50 –40 –30 INPUT AMPLITUDE (dBFS) –20 –10 0 09180-130 –80 –120 –90 Figure 30. AD9644-155 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 180 MHz, fS = 80 MSPS –66 –54 –42 –30 INPUT AMPLITUDE (dBFS) –18 –6 Figure 33. AD9644-155 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 29.9 MHz, fIN2 = 32.9 MHz, fS = 80 MSPS 100 0 95 –20 SFDR/IMD3 (dBc AND dBFS) SNR/SFDR (dBFS/dBc) –78 09180-133 IMD3 (dBFS) 0 –90 90 SNR @ –40°C SFDR @ –40°C SNR @ +25°C SFDR @ +25°C SNR @ +85°C SFDR @ +85°C 85 80 75 –40 SFDR (dBc) –60 IMD3 (dBc) –80 SFDR (dBFS) –100 70 50 100 150 200 INPUT FREQUENCY (MHz) 250 300 09180-131 0 –120 –90 Figure 31. AD9644-155 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and Temperature with 1.75 V p-p Full-Scale, fS = 80 MSPS –78 –66 –54 –42 –30 INPUT AMPLITUDE (dBFS) –18 –6 09180-134 IMD3 (dBFS) 65 Figure 34. AD9644-155 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 169.1 MHz, fIN2 = 172.1 MHz, fS = 80 MSPS Rev. C | Page 17 of 44 AD9644 Data Sheet 0 4000 155MSPS 29.9MHz @ –7dBFS 32.9MHz @ –7dBFS SFDR = 89.8dBc (96.8dBFS) –20 3500 3000 NUMBER OF HITS AMPLITUDE (dBFS) –40 –60 –80 2500 2000 1500 –100 1000 –120 0 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) 0 09180-135 –140 N–5N–4N–3N–2N–1 N N+1N+2N+3N+4N+5 OUTPUT CODE Figure 35. AD9644-155 Two-Tone FFT with fIN1 = 29.9 MHz and fIN2 = 32.9 MHz Figure 38. AD9644-155 Grounded Input Histogram 0 1 155MSPS 169.1MHz @ –7dBFS 172.1MHz @ –7dBFS SFDR = 89.1dBc (96.1dBFS) –20 0.8 0.6 –40 0.4 INL ERROR (LSB) AMPLITUDE (dBFS) 09180-138 500 –60 –80 0.2 0 –0.2 –0.4 –100 –0.6 –120 7.75 15.50 23.25 31.00 38.75 46.50 54.25 62.00 69.75 77.50 FREQUENCY (MHz) –1 09180-136 0 0 Figure 36. AD9644-155 Two-Tone FFT with fIN1 = 169.1 MHz and fIN2 = 172.1 MHz 2000 4000 6000 8000 10000 OUTPUT CODE 12000 14000 16000 09180-139 –0.8 –140 Figure 39. AD9644-155 INL with fIN = 30.3 MHz 100 0.5 0.25 90 DNL ERROR (LSB) SNR/SFDR (dBFS/dBc 95 85 SNR, CHANNEL B SFDR, CHANNEL B SNR, CHANNEL A SFDR, CHANNEL A 80 0 –0.25 65 80 95 110 125 SAMPLE RATE (MSPS) 140 155 –0.5 0 Figure 37. AD9644-155 Single-Tone SNR/SFDR vs. Sample Rate (fS) with fIN = 70. MHz 2000 4000 6000 8000 10000 OUTPUT CODE 12000 14000 16000 Figure 40. AD9644-155 DNL with fIN = 30.3 MHz Rev. C | Page 18 of 44 09180-140 70 50 09180-137 75 Data Sheet AD9644 EQUIVALENT CIRCUITS AVDD 350Ω SCLK OR PDWN 30kΩ 09180-012 09180-008 VIN Figure 41. Equivalent Analog Input Circuit Figure 45. Equivalent SCLK or PDWN Input Circuit AVDD AVDD AVDD AVDD 30kΩ 0.9V 15kΩ 350Ω CLK– 09180-014 09180-009 CLK+ CSB 15kΩ Figure 42. Equivalent Clock Input Circuit Figure 46. Equivalent CSB Input Circuit DRVDD RTERM VCM DOUT±A/B AVDD 4mA DOUT±A/B DSYNC±A/B OR SYNC 0.9V Figure 43. Digital CML Output Figure 47. Equivalent SYNC and DSYNC Input Circuit DRVDD 350Ω 30kΩ 09180-011 SDIO 0.9V 16kΩ 4mA 09180-089 4mA AVDD 09180-025 4mA Figure 44. Equivalent SDIO Circuit Rev. C | Page 19 of 44 AD9644 Data Sheet THEORY OF OPERATION In nondiversity applications, the AD9644 can be used as a baseband or direct downconversion receiver, in which one ADC is used for I input data, and the other is used for Q input data. Synchronization capability is provided to allow synchronized timing between multiple devices. Programming and control of the AD9644 are accomplished using a 3-wire SPI-compatible serial interface. ADC ARCHITECTURE The AD9644 architecture consists of a dual front-end sampleand-hold circuit, followed by a pipelined, switched-capacitor ADC. 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 on a new input sample and the remaining stages to operate on the preceding samples. Sampling occurs on the rising edge of the clock. Each stage of the pipeline, excluding the last, consists of a low resolution flash ADC connected to a switched-capacitor digitalto-analog converter (DAC) and an interstage residue amplifier (MDAC). The MDAC magnifies the difference between the reconstructed DAC output and the flash input for the next stage in the pipeline. One bit of redundancy is used in each stage to facilitate digital correction of flash errors. The last stage simply consists of a flash ADC. The input stage of each channel contains a differential sampling circuit that can be ac- or dc-coupled in differential or singleended modes. The output staging block aligns the data, corrects errors, and passes the data to the output buffers. The output buffers are powered from a separate supply, allowing digital output noise to be separated from the analog core. During power-down, the output buffers go into a high impedance state. ANALOG INPUT CONSIDERATIONS The analog input to the AD9644 is a differential switchedcapacitor circuit that has been designed for optimum performance while processing a differential input signal. The clock signal alternatively switches the input between sample mode and hold mode (see Figure 48). When the input is switched into sample mode, the signal source must be capable of charging the sample capacitors and settling within ½ of a clock cycle. A small resistor in series with each input can help reduce the peak transient current required from the output stage of the driving source. A shunt capacitor can be placed across the inputs to provide dynamic charging currents. This passive network creates a low-pass filter at the ADC input; therefore, the precise values are dependent on the application. In intermediate frequency (IF) undersampling applications, any shunt capacitors or series resistors should be reduced since the input sample capacitor is unbuffered. In combination with the driving source impedance, the shunt capacitors limit the input bandwidth. Refer to the AN-742 Application Note, Frequency Domain Response of Switched-Capacitor ADCs; the AN-827 Application Note, A Resonant Approach to Interfacing Amplifiers to Switched-Capacitor ADCs; and the Analog Dialog article, “Transformer-Coupled Front-End for Wideband A/D Converters,” for more information on this subject (refer to www.analog.com). BIAS S S CFB CS VIN+ CPAR1 CPAR2 H S S CS VIN– CPAR1 CPAR2 S CFB S BIAS 09180-034 The AD9644 dual-core analog-to-digital converter (ADC) can be used for diversity reception of signals, in which the ADCs are operating identically on the same carrier but from two separate antennae. The ADCs can also be operated with independent analog inputs. The user can sample any fS/2 frequency segment from dc to 250 MHz, using appropriate low-pass or band-pass filtering at the ADC inputs with little loss in ADC performance. Figure 48. Switched-Capacitor Input For best dynamic performance, the source impedances driving VIN+ and VIN− should be matched, and the inputs should be differentially balanced. Input Common Mode The analog inputs of the AD9644 are not internally dc biased. In ac-coupled applications, the user must provide this bias externally. Setting the device so that VCM = 0.5 × AVDD (or 0.9 V) is recommended for optimum performance. An onboard common-mode voltage reference is included in the design and is available from the VCMA and VCMB pins. Using the VCMA and VCMB outputs to set the input common mode is recommended. Optimum performance is achieved when the common-mode voltage of the analog input is set by the VCMA and VCMB pin voltages (typically 0.5 × AVDD). The VCMA and VCMB pins must be decoupled to ground by a 0.1 µF capacitor. This decoupling capacitor should be placed close to the pin to minimize the series resistance and inductance between the part and this capacitor. Rev. C | Page 20 of 44 Data Sheet AD9644 Differential Input Configurations The signal characteristics must be considered when selecting a transformer. Most RF transformers saturate at frequencies below a few megahertz (MHz). Excessive signal power can also cause core saturation, which leads to distortion. Optimum performance is achieved while driving the AD9644 in a differential input configuration. For baseband applications, the AD8138, ADA4937-2, and ADA4938-2 differential drivers provide excellent performance and a flexible interface to the ADC. At input frequencies in the second Nyquist zone and above, the noise performance of most amplifiers is not adequate to achieve the true SNR performance of the AD9644. For applications in which SNR is a key parameter, differential double balun coupling is the recommended input configuration (see Figure 51). In this configuration, the input is ac-coupled and the VCM is provided to each input through a 33 Ω resistor. These resistors compensate for losses in the input baluns to provide a 50 Ω impedance to the driver. The output common-mode voltage of the ADA4938-2 is easily set with the VCM pin of the AD9644 (see Figure 49), and the driver can be configured in a Sallen-Key filter topology to provide band limiting of the input signal. 15pF 200Ω 33Ω 90Ω 15Ω VIN– AVDD 5pF 33Ω 15Ω VCM VIN+ 15pF 200Ω 09180-039 120Ω In the double balun and transformer configurations, the value of the input capacitors and resistors is dependent on the input frequency and source impedance. Based on these parameters the value of the input resistors and capacitors may need to be adjusted or some components may need to be removed. Table 9 displays recommended values to set the RC network for different input frequency ranges. However, these values are dependent on the input signal and bandwidth and should be used only as a starting guide. Note that the values given in Table 9 are for each R1, R2, C2, and R3 component shown in Figure 50 and Figure 51. ADC ADA4938-2 0.1µF Figure 49. Differential Input Configuration Using the ADA4938-2 For baseband applications in which SNR is a key parameter, differential transformer coupling is the recommended input configuration. An example is shown in Figure 50. To bias the analog input, the VCM voltage can be connected to the center tap of the secondary winding of the transformer. Table 9. Example RC Network C2 R3 R2 VIN+ R1 49.9Ω C1 ADC R2 R1 0.1µF VCM VIN– R3 C2 R2 Series (Ω) 0 0 C1 Differential (pF) 8.2 3.9 Figure 50. Differential Transformer-Coupled Configuration C2 R3 R1 0.1µF 0.1µF 2V p-p R2 VIN+ 33Ω PA S S P C1 0.1µF C2 Shunt (pF) 8.2 Open R3 Shunt (Ω) 49.9 Open An alternative to using a transformer-coupled input at frequencies in the second Nyquist zone is to use the AD8376 variable gain amplifier. An example drive circuit including a band-pass filter is shown in Figure 52. See the AD8376 data sheet for more information. 09180-040 2V p-p R1 Series (Ω) 33 15 Frequency Range (MHz) 0 to 100 100 to 250 33Ω ADC 0.1µF R1 R2 R3 C2 Figure 51. Differential Double Balun Input Configuration Rev. C | Page 21 of 44 VIN– VCM 09180-041 76.8Ω VIN AD9644 Data Sheet 1000pF 180nH 220nH 1µH 165Ω VPOS AD8376 301Ω 5.1pF 1nF 1µH 3.9pF 165Ω 15pF VCM 1nF 1000pF AD9644 68nH 180nH 220nH 09180-115 NOTES 1. ALL INDUCTORS ARE COILCRAFT 0603CS COMPONENTS WITH THE EXCEPTION OF THE 1µH CHOKE INDUCTORS (0603LS). Figure 52. Differential Input Configuration Using the AD8376 (Filter Values Shown Are for a 20 MHz Bandwidth Filter Centered at 140 MHz) A stable and accurate voltage reference is built into the AD9644. The input full scale range can be adjusted through the SPI port by adjusting Bit 0 through Bit 4 of Register 0x18. These bits can be used to change the full scale between 1.383 V p-p and 2.087 V p-p in 0.022 V steps, as shown in Table 17. secondary limit clock excursions into the AD9644 to approximately 0.8 V p-p differential. This limit helps prevent the large voltage swings of the clock from feeding through to other portions of the AD9644 while preserving the fast rise and fall times of the signal that are critical to a low jitter performance. CLOCK INPUT CONSIDERATIONS For optimum performance, the AD9644 sample clock inputs, CLK+ and CLK−, should be clocked with a differential signal. The signal is typically ac-coupled into the CLK+ and CLK− pins by means of a transformer or a passive component configuration. These pins are biased internally (see Figure 53) and require no external bias. If the inputs are floated, the CLK− pin is pulled low to prevent inadvertent clocking. Mini-Circuits® ADT1-1WT, 1:1Z 0.1µF XFMR 0.1µF CLOCK INPUT ADC CLK+ 100Ω 50Ω 0.1µF CLK– SCHOTTKY DIODES: HSMS2822 0.1µF 09180-048 VOLTAGE REFERENCE Figure 54. Transformer-Coupled Differential Clock (Up to 200 MHz) AVDD ADC 1nF CLOCK INPUT CLK– 0.1µF 1nF 2pF CLK– SCHOTTKY DIODES: HSMS2822 09180-044 2pF CLK+ 50Ω Figure 55. Balun-Coupled Differential Clock (Up to 640 MHz) Figure 53. Equivalent Clock Input Circuit Clock Input Options The AD9644 has a very flexible clock input structure. Clock input can be a CMOS, LVDS, LVPECL, or sine wave signal. Regardless of the type of signal being used, clock source jitter is of the most concern, as described in the Jitter Considerations section. The minimum conversion rate of the AD9644 is 40 MSPS. At clock rates below 40 MSPS, dynamic performance of the AD9644 can degrade. Figure 54 and Figure 55 show two preferred methods for clocking the AD9644 (at clock rates up to 640 MHz). A low jitter clock source is converted from a single-ended signal to a differential signal using either an RF balun or an RF transformer. If a low jitter clock source is not available, another option is to ac couple a differential PECL signal to the sample clock input pins, as shown in Figure 56. The AD9510/AD9511/AD9512/ AD9513/AD9514/AD9515/AD9516/AD9517/AD9518/AD9520 /AD9522 clock drivers offer excellent jitter performance. 0.1µF 0.1µF CLOCK INPUT CLK+ AD95xx 0.1µF CLOCK INPUT The RF balun configuration is recommended for clock frequencies between 125 MHz and 640 MHz, and the RF transformer is recommended for clock frequencies from 40 MHz to 200 MHz. The back-to-back Schottky diodes across the transformer/balun Rev. C | Page 22 of 44 PECL DRIVER 100Ω ADC 0.1µF CLK– 50kΩ 50kΩ 240Ω 240Ω Figure 56. Differential PECL Sample Clock (Up to 640 MHz) 09180-050 CLK+ 0.1µF 09180-049 0.9V Data Sheet AD9644 A third option is to ac-couple a differential LVDS signal to the sample clock input pins, as shown in Figure 57. The AD9510/ AD9511/AD9512/AD9513/AD9514/AD9515/AD9516/AD9517/ AD9518/AD9520/AD9522 clock drivers offer excellent jitter performance. 0.1µF 0.1µF CLOCK INPUT CLK+ AD95xx 0.1µF ADC 0.1µF CLK– 50kΩ 09180-051 CLOCK INPUT LVDS DRIVER 100Ω 50kΩ Jitter Considerations Figure 57. Differential LVDS Sample Clock (Up to 640 MHz) In some applications, it may be acceptable to drive the sample clock inputs with a single-ended CMOS signal. In such applications, the CLK+ pin should be driven directly from a CMOS gate, and the CLK− pin should be bypassed to ground with a 0.1 μF capacitor (see Figure 58). VCC CLOCK INPUT 0.1µF 1kΩ AD95xx OPTIONAL 0.1µF 100Ω CMOS DRIVER 50Ω 1 CLK+ ADC 1kΩ CLK– 09180-052 0.1µF 150Ω Jitter in the rising edge of the input is still of paramount concern and is not easily reduced by the internal stabilization circuit. The loop has a time constant associated with it that must be considered in applications in which the clock rate can change dynamically. A wait time of 1.5 μs to 5 μs is required after a dynamic clock frequency increase or decrease before the DCS loop is relocked to the input signal. During the time period that the loop is not locked, the DCS loop is bypassed, and internal device timing is dependent on the duty cycle of the input clock signal. In such applications, it may be appropriate to disable the duty cycle stabilizer. In all other applications, enabling the DCS circuit is recommended to maximize ac performance. RESISTOR IS OPTIONAL. High speed, high resolution ADCs are sensitive to the quality of the clock input. For inputs near full scale, the degradation in SNR from the low frequency SNR (SNRLF) at a given input frequency (fINPUT) due to jitter (tJRMS) can be calculated by SNRHF = −10 log[(2π × fINPUT × tJRMS)2 + 10 ( SNR LF / 10 ) ] In the equation, the rms aperture jitter represents the clock input jitter specification. IF undersampling applications are particularly sensitive to jitter, as illustrated in Figure 59. The measured curve in Figure 59 was taken using an ADC clock source with approximately 65 fs of jitter, which combines with the 125 fs of jitter inherent in the AD9644 to produce the result shown. 75 Figure 58. Single-Ended 1.8 V CMOS Input Clock (Up to 200 MHz) 70 The AD9644 clock divider can be synchronized using the external SYNC input. Bit 1 and Bit 2 of Register 0x3A allow the clock divider to be resynchronized on every SYNC signal or only on the first SYNC signal after the register is written. A valid SYNC causes the clock divider to reset to its initial state. This synchronization feature allows multiple parts to have their clock dividers aligned to guarantee simultaneous input sampling. Clock Duty Cycle Typical high speed ADCs use both clock edges to generate a variety of internal timing signals and, as a result, may be sensitive to clock duty cycle. The AD9644 requires a tight tolerance on the clock duty cycle to maintain dynamic performance characteristics. The AD9644 contains a duty cycle stabilizer (DCS) that retimes the nonsampling (falling) edge, providing an internal clock signal with a nominal 50% duty cycle. This allows the user to provide a wide range of clock input duty cycles without affecting the performance of the AD9644. Noise and distortion performance are nearly flat for a wide range of duty cycles with the DCS enabled. 0.05ps 0.2ps 0.5ps 1ps 1.5ps MEASURED 65 60 55 50 1 10 100 INPUT FREQUENCY (MHz) 1000 09180-043 The AD9644 contains an input clock divider with the ability to divide the input clock by integer values between 1 and 8. For divide ratios other than 1 the duty cycle stabilizer is automatically enabled. SNR (dBFS) Input Clock Divider Figure 59. SNR vs. Input Frequency and Jitter The clock input should be treated as an analog signal in cases in which aperture jitter may affect the dynamic range of the AD9644. Power supplies for clock drivers should be separated from the ADC output driver supplies to avoid modulating the clock signal with digital noise. Low jitter, crystal-controlled oscillators make the best clock sources. If the clock is generated from another type of source (by gating, dividing, or another method), it should be retimed by the original clock at the last step. Refer to the AN-501 Application Note and the AN-756 Application Note (visit www.analog.com) for more information about jitter performance as it relates to ADCs. Rev. C | Page 23 of 44 AD9644 Data Sheet CHANNEL/CHIP SYNCHRONIZATION By asserting PDWN (either through the SPI port or by asserting the PDWN pin high), the AD9644 is placed in power-down mode. In this state, the ADC typically dissipates 15 mW. During powerdown, the output drivers are placed in a high impedance state. Asserting the PDWN pin low returns the AD9644 to its normal operating mode. The AD9644 has a SYNC input that offers the user flexible synchronization options for synchronizing the clock divider. The clock divider sync feature is useful for guaranteeing synchronized sample clocks across multiple ADCs. The input clock divider can be enabled to synchronize on a single occurrence of the SYNC signal or on every occurrence. The SYNC input is internally synchronized to the sample clock; however, to ensure that there is no timing uncertainty between multiple parts, the SYNC input signal should be externally synchronized to the input clock signal, meeting the setup and hold times shown in Table 5. The SYNC input should be driven using a single-ended CMOS-type signal. POWER DISSIPATION AND STANDBY MODE As shown in Figure 60 and Figure 61, the power dissipated by the AD9644 varies with its sample rate (AD9644-80 shown). JESD204A Transmit Top Level Description The AD9644 digital output complies with the JEDEC Standard No. 204A (JESD204A), which describes a serial interface for data converters. JESD204A uses 8B/10B encoding as well as optional scrambling. K28.5 and K28.7 comma symbols are used for frame synchronization and the K28.3 control symbol is used for lane synchronization. The receiver is required to lock onto the serial data stream and recover the clock with the use of a PLL. For details on the output interface, users are encouraged to refer to the JESD204A standard. 0.25 TOTAL POWER 0.20 IAVDD 0.3 0.15 0.2 0.10 SUPPLY CURRENT (A) TOTAL POWER (W) 0.4 IDRVDD 0.1 0.05 50 60 70 0 80 09180-144 0 40 ENCODE FREQUENCY (MSPS) Figure 60. AD9644-80 Power and Current vs. Encode Frequency with fIN = 10.1 MHz 0.60 0.35 TOTAL POWER 0.20 0.30 0.15 0.20 IDRVDD 0.10 0.10 0 80 0.05 0 90 100 110 120 130 140 ENCODE FREQUENCY (MSPS) 150 Figure 61. AD9644-155 Power and Current vs. Encode Frequency with fIN = 10.1 MHz 09180-061 TOTAL POWER (W) 0.25 IAVDD 0.40 SUPPLY CURRENT (A) 0.30 0.50 When using the SPI port interface, the user can place the ADC in power-down mode or standby mode. Standby mode allows the user to keep the internal reference circuitry powered and the JESD204A outputs running when faster wake-up times are required. DIGITAL OUTPUTS The data in Figure 60 and Figure 61 was taken in JESD204A serial output mode, using the same operating conditions as those used for the Typical Performance Characteristics. 0.5 Low power dissipation in power-down mode is achieved by shutting down the reference, reference buffer, biasing networks, clock, and JESD204A outputs . Internal capacitors are discharged when entering power-down mode and then must be recharged when returning to normal operation. The JESD204A transmit block is used to multiplex data from the two analog-to-digital converters onto two independent JESD204A Links. Each JESD204A Link is considered a separate instance of the JESD204A specification, has an independent DSYNC signal, and contains one or more lanes. Note that the JESD204 specification only allows one lane per link, while the JESD204A specification adds multilane support through an alignment procedure. Each JESD204A Link is described according to the following nomenclature: • S = samples transmitted/single converter/frame cycle • M = number of converters/converter device (link) • L = number of lanes/converter device (link) • N = converter resolution • N’ = total number of bits per sample • CF = number of control words/frame clock cycle/converter device (link) • CS = number of control bits/conversion sample • K = number of frames per multiframe • HD = high density mode • F = octets/frame • C = control bit (overrange, overflow, underflow) • T = tail bit • SCR = scrambler enable/disable • FCHK = checksum Rev. C | Page 24 of 44 Data Sheet AD9644 Figure 62 shows a simplified block diagram of the AD9644 JESD204A links. The two links each have a primary and a secondary converter input and lane output. By default, the primary Input 0 of Link A is ADC Converter A and its primary lane Output 0 is sent on output Lane A. The primary Input 0 of Link B is ADC Converter B and its primary lane Output 0 is sent on output Lane B. Muxes throughout the design are used to enable secondary inputs/outputs and swap lane outputs for other configurations. The JESD204A block for AD9644 is designed to support the configurations described in Table 10 via a quick configuration register at Address 0x5E accessible via the SPI bus. In addition to the default mode, the user can program the AD9644 to output both ADC channels on a single lane (F = 4). This mode allows use of a single high speed data lane, which simplifies board layout and connector requirements. In Figure 64 the ADC A output is represented by Word 0 and the ADC B output by Word 1. The third output mode utilizes a single link to support both channels. In single link mode, the DSYNCA pin is used to support both outputs. This mode is useful for optimal alignment between the output channels. The 8B/10B encoding works by taking eight bits of data (an octet) and encoding them into a 10-bit symbol. By default in the AD9644, the 14-bit converter word is broken into two octets. Bit 13 through Bit 6 are in the first octet. The second octet contains Bit 5 through Bit 0 and two tail bits. The MSB of the tail bits can also be used to indicate an out-of-range condition. The tail bits are configured using the JESD204A link control Register 1, Address 0x60, Bit 6. The two resulting octets are optionally scrambled and encoded into their corresponding 10-bit code. The scrambling function is controlled by the JESD204A scrambling and lane configuration register, Address 0x06E, Bit 7. Figure 63 shows how the 14-bit data is taken from the ADC, the tail bits are added, the two octets are scrambled, and how the octets are encoded into two 10-bit symbols. Figure 63 illustrates the default data format. The scrambler uses a self-synchronizing polynomial-based algorithm defined by the equation 1 + x14 + x15. The descrambler in the receiver should be a self-synchronizing version of the scrambler polynomial. Figure 65 shows the corresponding receiver data path. Refer to JEDEC Standard No. 204A-April 2008, Section 5.1, for complete transport layer and data format details and Section 5.2 for a complete explanation of scrambling and descrambling. AD9644 DUAL ADC CONVERTER A CONVERTER A SAMPLE PRIMARY LANE 0 A PRIMARY CONVERTER LANE INPUT [0] OUTPUT [0] JESD204A LINK A (M = 0, 1, 2; L = 0, 1, 2) B SECONDARY CONVERTER INPUT [1] SECONDARY LANE 1 LANE OUTPUT [1] A SECONDARY SECONDARY LANE 1 CONVERTER LANE INPUT [1] OUTPUT [1] JESD204A LINK B (M = 0, 1, 2; L = 0, 1, 2) CONVERTER B INPUT CONVERTER B CONVERTER B SAMPLE B PRIMARY CONVERTER INPUT [0] LANE A PRIMARY LANE 0 LANE OUTPUT [0] LANE MUX (SPI REGISTER 0x5F) LANE B LINK B ~SYNC Figure 62. AD9644 Transmit Link Simplified Block Diagram Rev. C | Page 25 of 44 09180-045 CONVERTER A INPUT LINK A ~SYNC AD9644 Data Sheet Table 10. AD9644 JESD204A Typical Configurations JESK204A Link A Settings M = 1; L = 1; S = 1; F = 2 N’ = 16; CF = 0 CS = 0, 1, 2; K = N/A SCR = 0, 1; HD = 0 M = 2; L = 2; S = 1; F = 2 N’ = 16 Two Converters Two JESD204A Links One Lane Per Link Two Converters One JESD204A Link Two Lanes Per Link CF = 0; CS = 0, 1, 2 K = 16; SCR = 0, 1; HD = 0 M = 2; L = 1; S = 1; F = 4 N’ = 16 CF = 0; CS = 0, 1, 2 K = 8; SCR = 0, 1; HD = 0 Two Converters One JESD204A Link One Lane Per Link DATA FROM ADC JESD204A Link B Settings M = 1; L = 1; S = 1; F = 2 N’ = 16; CF = 0 CS = 0, 1, 2; K = N/A SCR = 0, 1; HD = 0 Disabled Disabled FRAME ASSEMBLER (ADD TAIL BITS) Comments Maximum sample rate = 80 MSPS or 155 MSPS Maximum sample rate = 80 MSPS or 155 MSPS Required for applications needing two aligned samples (I/Q applications) Maximum sample rate = 80 MSPS OPTIONAL SCRAMBLER 1 + x14 + x15 8B/10B ENCODER TO RECEIVER 09180-201 AD9644 Configuration Figure 63. AD9644 ADC Output Data Path WORD 0[13:6] SYMBOL 0[9:0] FRAME 0 WORD 0[5:0],TAIL BITS[1:0] SYMBOL 1[9:0] WORD 1[13:6] SYMBOL 2[9:0] WORD 1[5:0], TAIL BITS[1:0] SYMBOL 3[9:0] TIME 09180-200 FRAME 1 FROM TRANSMITTER 8B/10B DECODER OPTIONAL DESCRAMBLER 1 + x14 + x15 FRAME ALIGNMENT DATA OUT 09180-202 Figure 64. AD9644 14-Bit Data Transmission with Tail Bits Figure 65. Required Receiver Data Path Initial Frame Synchronization The serial interface must synchronize to the frame boundaries before data can be properly decoded. The JESD204A standard has a synchronization routine to identify the frame boundary. When the DSYNC pin is taken low for at least two clock cycles, the AD9644 enters the code group synchronization mode. The AD9644 transmits the K28.5 comma symbol until the receiver achieves synchronization. The receiver should then deassert the sync signal (take DSYNC high) and the AD9644 begins the initial lane alignment sequence (when enabled through Bits[3:2] of Address 0x60) and subsequently begins transmitting sample data. The first non-K28.5 symbol corresponds to the first octet in a frame. The DSYNC input can be driven either from a differential LVDS source or by using a single-ended CMOS driver circuit. The DSYNC input default to LVDS mode but can be set to CMOS mode by setting Bit 4 in SPI Address 0x61. If it is driven differentially from an LVDS source, then an external 100 Ω termination resistor should be provided. If the DSYNC input is driven single-ended then the CMOS signal should be connected to the DSYNC+ signal and the DSYNC− signal should be left disconnected. Rev. C | Page 26 of 44 Data Sheet AD9644 Table 11. AD9644 JESD204A Frame Alignment Monitoring and Correction Replacement Characters Character to be Replaced Last octet in frame repeated from previous frame Last octet in frame repeated from previous frame Last octet in frame repeated from previous frame Last octet in frame equals D28.7 (0xFC) Last octet in frame equals D28.3 (0x7C) Last octet in frame equals D28.7 (0x7C) Frame and Lane Alignment Monitoring and Correction Frame alignment monitoring and correction is part of the JESD204A specification. The 14-bit word requires two octets to transmit all the data. The two octets (MSB and LSB), where F = 2, make up a frame. During normal operating conditions frame alignment is monitored via alignment characters, which are inserted under certain conditions at the end of a frame. Table 11 summarizes the conditions for character insertion along with the expected characters under the various operation modes. If lane synchronization is enabled, the replacement character value depends on whether the octet is at the end of a frame or at the end of a multiframe. Based on the operating mode, the receiver can ensure that it is still synchronized to the frame boundary by correctly receiving the replacement characters. Last Octet in Multiframe No Yes Not applicable No Yes Not applicable Replacement Character K28.7 (0xFC) K28.3 (0x7C) K28.7 (0xFC) K28.7 (0xFC) K28.3 (0x7C) K28.7 (0xFC) common mode of the digital output automatically biases itself to half the supply of the receiver (that is, the common-mode voltage is 0.9 V for a receiver supply of 1.8 V) if dc-coupled connecting is used (see Figure 67). For receiver logic that is not within the bounds of the DRVDD supply, an ac-coupled connection should be used. Simply place a 0.1 μF capacitor on each output pin and derive a 100 Ω differential termination close to the receiver side. If there is no far-end receiver termination or if there is poor differential trace routing, timing errors may 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. VRXCM DRVDD Digital Outputs and Timing The AD9644 has differential digital outputs that power up by default. The driver current is derived on chip and sets the output current at each output equal to a nominal 4 mA. Each output presents a 100 Ω dynamic internal termination to reduce unwanted reflections. A 100 Ω differential termination resistor should be placed at each receiver input to result in a nominal 400 mV peak-to-peak swing at the receiver (see Figure 66). Alternatively, single-ended 50 Ω termina-tion can be used. When single-ended termination is used, the termination voltage should be DRVDD/2; otherwise, ac coupling capacitors can be used to terminate to any singleended voltage. The AD9644 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 logic as possible. The Rev. C | Page 27 of 44 100Ω DIFFERENTIAL 0.1µF TRACE PAIR DOUT+x 100Ω DOUT–x OR RECEIVER 0.1µF VCM = Rx VCM OUTPUT SWING = 400mV p-p 09180-093 Lane Synchronization On On Off On On Off Figure 66. AC-Coupled Digital Output Termination Example DRVDD 100Ω DIFFERENTIAL TRACE PAIR DOUT+x 100Ω RECEIVER DOUT–x OUTPUT SWING = 400mV p-p VCM = DRVDD/2 Figure 67. DC-Coupled Digital Output Termination Example 09180-092 Scrambling Off Off Off On On On AD9644 Data Sheet HEIGHT1: EYE DIAGRAM PERIOD1: HISTOGRAM 1 – 100 4 25,000 + WIDTH@BER1: BATHTUB 3 + 10–2 400 20,000 10–4 0 10–6 15,000 BER HITS 10–8 10,000 –200 10–10 5000 –400 EYE: TRANSITION BITS OFFSET: –0.004 ULS: 8000; 639999, TOTAL: 8000; 639999 –600 –400 –200 0 200 TIME (ps) 400 0 600 10–12 610 615 620 625 630 TIME (ps) 0.781 10–14 –0.5 635 0 ULS 09180-094 VOLTAGE (mV) 200 0.5 Figure 68. AD9644-80 Digital Outputs Data Eye, Histogram and Bathtub, External 100 Ω Terminations HEIGHT1: EYE DIAGRAM PERIOD1: HISTOGRAM 1 500 50,000 – 400 WIDTH@BER1: BATHTUB 3 – 10–2 40,000 200 10–4 35,000 0 –100 10–6 30,000 BER 100 HITS 25,000 10–8 20,000 –200 10–10 15,000 –300 10,000 –400 EYE: TRANSITION BITS OFFSET: –0.004 ULS: 8000; 124,0001, TOTAL: 8000; 124,0001 –300 –200 –100 0 100 TIME (ps) 200 300 10–12 0.742 5000 0 305 310 315 320 325 TIME (ps) 330 335 10–14 –0.5 0 ULS 0.5 09180-069 VOLTAGE (mV) – 45,000 300 –500 100 4 Figure 69. AD9644-155 Digital Outputs Data Eye, Histogram and Bathtub, External 100 Ω Terminations Figure 68 and Figure 69 shows an example of the digital output (default) data eye and a time interval error (TIE) jitter histogram. Additional SPI options allow the user to further increase the output driver voltage swing of all four outputs to drive longer trace lengths (see Address 0x15 in Table 17). Even though this produces sharper rise and fall times on the data edges and is less prone to bit errors, the power dissipation of the DRVDD supply increases when this option is used. See the Memory Map section for more details. The format of the output data is twos complement by default. Table 12 provides an example of this output coding format. To change the output data format to offset binary or gray code, see the Memory Map section (Address 0x14 in Table 17). Table 12. Digital Output Coding Code 8191 0 −1 −8192 (VIN+ ) − (VIN− ), Input Span = 1.75 V p-p (V) +0.875 0.00 −0.000107 −0.875 Digital Output Twos Complement ([D13:D0]) 01 1111 1111 1111 00 0000 0000 0000 11 1111 1111 1111 10 0000 0000 0000 The lowest typical clock rate is 40 MSPS. For clock rates slower than 60 MSPS, the user should set Bit 3 to 0 in the serial control register (Address 0x21 in Table 17). This option sets the PLL loop bandwidth to use clock rates between 40 MSPS and 60 MSPS. Setting Bit 2 in the output mode register (Address 0x14) allows the user to invert the digital samples from their nominal state. As shown in Figure 64, the MSB is transmitted first in the data output serial stream. Rev. C | Page 28 of 44 Data Sheet AD9644 BUILT-IN SELF-TEST (BIST) AND OUTPUT TEST The AD9644 includes built-in test features designed to enable verification of the integrity of each channel as well as facilitate board level debugging. A BIST (built-in self-test) feature is included that verifies the integrity of the digital datapath of the AD9644. Various output test options are also provided to place predictable values on the outputs of the AD9644. BUILT-IN SELF-TEST (BIST) The BIST is a thorough test of the digital portion of the selected AD9644 signal path. When enabled, the test runs from an internal pseudorandom noise (PN) source through the digital datapath starting at the ADC block output. The BIST sequence runs for 512 cycles and stops. The BIST signature value for Channel A and/or Channel B is placed in Register 0x24 and Register 0x25. The outputs are not disconnected during this test, so the PN sequence can be observed as it runs. The PN sequence can be continued from its last value or reset from the beginning, based on the value programmed in Register 0x0E, Bit 2. The BIST signature result varies based on the channel configuration. OUTPUT TEST MODES Digital Test patterns can be inserted at various points along the signal path within the AD9644 as shown in Figure 70. The ability to inject these signals at several locations facilitates debugging of the JESD204A serial communication link. The Register 0x0D allows test signals generated at the output of the ADC core to be fed directly into the input of the serial Link. The output test options available from Register 0x0D are shown in Table 17. 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 seed value for the PN sequence tests can be forced if the PN reset bits are used to hold the generator in reset mode by setting Bit 4 or Bit 5 of Register 0x0D. These tests can be performed with or without an analog signal (if present, the analog signal is ignored), but they do require an encode clock. For more information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. There are nine digital output test pattern options available that can be initiated through the SPI (see Table 14 for the output bit sequencing options). This feature is useful when validating receiver capture and timing. Some test patterns have two serial sequential words and can be alternated in various ways, depending on the test pattern selected. Note that some patterns do not adhere to the data format select option. In addition, custom user-defined test patterns can be assigned in the user pattern registers (Address 0x19 through Address 0x20). The PN sequence short pattern produces a pseudorandom bit sequence that repeats itself every 29 − 1 (511) bits. A description of the PN sequence short and how it is generated can be found in Section 5.1 of the ITU-T O.150 (05/96) recommendation. The only difference is that the starting value must be a specific value instead of all 1s (see Table 13 for the initial values). The PN sequence long pattern produces a pseudorandom bit sequence that repeats itself every 223 − 1 (8,388,607) bits. A description of the PN sequence long and how it is generated can be found in Section 5.6 of the ITU-T O.150 (05/96) standard. The only differences are that the starting value must be a specific value instead of all 1s (see Table 13 for the initial values) and that the AD9644 inverts the bit stream with relation to the ITU-T standard. Table 13. PN Sequence Sequence PN Sequence Short PN Sequence Long Initial Value 0x0092 0x3AFF First Three Output Samples (MSB First) 0x125B, 0x3C9A, 0x2660 0x3FD7, 0x0002, 0x36E0 The Register 0x62 allows patterns similar to those described in Table 14 to be input at different points along the data path. This allows the user to provide predictable output data on the serial link without it having been manipulated by the internal formatting logic. Refer to Table 17 for additional information on the test modes available in Register 0x62. Rev. C | Page 29 of 44 AD9644 Data Sheet Table 14. Flexible Output Test Modes from SPI Register 0x0D 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 test mode 1001 to 1110 1111 Not used Ramp output ADC TEST PATTERNS 14-BIT SPI REGISTER 0x0D BITS 3:0 ≠ 0000 Digital Output Word 1 (Default Twos Complement Format) Not applicable 00 0000 0000 0000 01 1111 1111 1111 10 0000 0000 0000 10 1010 1010 1010 Not applicable Not applicable 1111 1111 1111 User data from Register 0x19 to Register 0x20 Not applicable N Digital Output Word 2 (Default Twos Complement Format) Not applicable Same Same Same 01 0101 0101 0101 Not applicable Not applicable 0000 0000 0000 User data from Register 0x19 to Register 0x20 Not applicable N+1 Subject to Data Format Select Yes Yes Yes Yes No Yes Yes No Yes No JESD204A TEST PATTERNS 10-BIT SPI REGISTER 0x62 BITS 5:4 = 01 AND BITS 2:0 ≠ 000 JESD204A TEST PATTERNS 16-BIT SPI REGISTER 0x62 BITS 5:4 = 00 AND BITS 2:0 ≠ 000 SERALIZER JESD204A SAMPLE CONSTRUCTION ADC CORE FRAME CONSTRUCTION SCRAMBLER (OPTIONAL) 8-BIT/10-BIT ENCODER OUTPUT 09180-149 FRAMER TAIL BITS Figure 70. Block Diagram Showing Digital Test Modes Rev. C | Page 30 of 44 Data Sheet AD9644 SERIAL PORT INTERFACE (SPI) The AD9644 serial port interface (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, which are documented in the Memory Map section. For detailed operational information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. The falling edge of the CSB, in conjunction with the rising edge of the SCLK, determines the start of the framing. An example of the serial timing and its definitions can be found in Figure 71 and Table 5. CONFIGURATION USING THE SPI During an instruction phase, a 16-bit instruction is transmitted. Data follows the instruction phase, and its length is determined by the W0 and W1 bits. Other modes involving the CSB are available. The CSB can be held low indefinitely, which permanently enables the device; this is called streaming. The CSB can stall high between bytes to allow for additional external timing. When CSB is tied high, SPI functions are placed in high impedance mode. Three pins define the SPI of this ADC: the SCLK pin, the SDIO pin, and the CSB pin (see Table 15). The SCLK (a serial clock) is used to synchronize the read and write data presented from and to the ADC. The SDIO (serial data input/output) is a dualpurpose pin that allows data to be sent to and read from the internal ADC memory map registers. The CSB (chip select bar) is an active-low control that enables or disables the read and write cycles. 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. The first bit of the first byte in a multibyte serial data transfer frame indicates whether a read command or a write command is issued. If the instruction is a readback operation, performing a readback causes the serial data input/output (SDIO) pin to change direction from an input to an output at the appropriate point in the serial frame. Table 15. Serial Port Interface Pins Pin SCLK SDIO CSB Function Serial Clock. The serial shift clock input 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. tHIGH tDS tS tDH All data is composed of 8-bit words. Data can be sent in MSBfirst 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 AN-877 Application Note, Interfacing to High Speed ADCs via SPI. tCLK tH tLOW CSB SDIO DON’T CARE DON’T CARE R/W W1 W0 A12 A11 A10 A9 A8 A7 D5 Figure 71. Serial Port Interface Timing Diagram Rev. C | Page 31 of 44 D4 D3 D2 D1 D0 DON’T CARE 09180-152 SCLK DON’T CARE AD9644 Data Sheet HARDWARE INTERFACE SPI ACCESSIBLE FEATURES The pins described in Table 15 comprise the physical interface between the user programming device and the serial port of the AD9644. 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. Table 16 provides a brief description of the general features that are accessible via the SPI. These features are described in detail in the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. The AD9644 part-specific features are described in detail in the Memory Map Register Descriptions section. 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. The SPI port should not be active 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 AD9644 to prevent these signals from transitioning at the converter inputs during critical sampling periods. Table 16. Features Accessible Using the SPI Feature Name Mode Clock Offset Test I/O Full Scale JESD204A Rev. C | Page 32 of 44 Description Allows the user to set either power-down mode or standby mode Allows the user to access the DCS, set the clock divider, set the clock divider phase, and enable the sync Allows the user to digitally adjust the converter offset Allows the user to set test modes to have known data on output bits Allows the user to set the input full scale voltage Allows user to configure the JESD204A output Data Sheet AD9644 MEMORY MAP Logic Levels READING THE MEMORY MAP REGISTER TABLE Each row in the memory map register table has eight bit locations. The memory map is roughly divided into four sections: the chip configuration registers (Address 0x00 to Address 0x02); the channel index and transfer registers (Address 0x05 and Address 0xFF); the ADC functions registers, including setup, control, and test (Address 0x08 to Address 0x3A); and the JESD204A configuration registers (Address 0x5E to Address 0x79). The memory map register table (see Table 17) lists 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 0x18, the input span select register, has a hexadecimal default value of 0x00. This means that Bit 0 through Bit 4 = 0, and the remaining bits are 0s. This setting is the default reference selection setting. The default value uses a 1.75 V p-p reference. For more information on this function and others, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. This application note details the functions con-trolled by Register 0x00 to Register 0xFF. Open Locations All address and bit locations that are not included in Table 17 are not currently supported for this device. Unused bits of a valid address location should be written with 0s. Writing to these locations is required only when part of an address location is open (for example, Address 0x18). If the entire address location is open (for example, Address 0x13), this address location should not be written. Default Values After the AD9644 is reset, critical registers are loaded with default values. The default values for the registers are given in the memory map register table, Table 17. An explanation of logic level terminology follows: • • “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.” Transfer Register Map Address 0x08 through Address 0x79 are shadowed. Writes to these addresses do not affect part operation until a transfer command is issued by writing 0x01 to Address 0xFF, setting the transfer bit. This allows these registers to be updated internally and simultaneously when the transfer bit is set. The internal update takes place when the transfer bit is set, and the bit autoclears. Channel-Specific Registers Some channel setup functions, such as the channel output mode, can be programmed differently for each ADC or link channel. In these cases, channel address locations are internally duplicated for each channel. These registers and bits are designated in Table 17 as local. These local registers and bits can be accessed by setting the appropriate Channel A/Link A or Channel B/Link B bits in Register 0x05. If both bits are set in register 0x05, the subsequent write affects the registers of both channels/links. In a SPI read cycle, only Channel A/Link A or Channel B/Link B should be set to read one of the two registers. If both bits are set during an SPI read cycle, the part returns the value for Channel A/Link A. Registers and bits designated as global in Table 17 affect the entire part or the channel features for which independent settings are not allowed between channels. The settings in Register 0x05 do not affect the global registers and bits. Rev. C | Page 33 of 44 AD9644 Data Sheet MEMORY MAP REGISTER TABLE All address and bit locations that are not included in Table 17 are not currently supported for this device. Table 17. Memory Map Registers Addr Register Bit 7 (Hex) Name (MSB) Chip Configuration Registers 0x00 0 SPI port configuration (global) 1 0x01 Chip ID (global) 0x02 Chip grade (global) Open Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 (LSB) LSB first Soft reset 1 1 Soft reset LSB first 0 8-bit chip ID[7:0] (AD9644 = 0x7E) (default) Speed grade ID Open 00 = 80 MSPS 10 = 155 MSPS Open Default Value (Hex) 0x18 0x7E Open Open Open Open Open Open Open ADC B and Link B (default) ADC A and Link A (default) 0x03 0xFF Transfer 0x00 Open Open Open Open Open Open Open ADC Functions 0x08 Power modes (local) Open Open External powerdown pin function (local) 0 = powerdown 1 = standby Open Open Open 0x09 Global clock (global) Open Open Open Open Open Open 0x0A PLL status (global) Clock divide (global) PLL Locked Open Open Open Open Open Open Internal power-down mode (local) 00 = normal operation 01 = full power-down 10 = standby 11 = reserved Open Duty cycle stabilizer (default) Open Open 0x0B Open Input clock divider phase adjust 000 = no delay 001 = 1 input clock cycle 010 = 2 input clock cycles 011 = 3 input clock cycles 100 = 4 input clock cycles 101 = 5 input clock cycles 110 = 6 input clock cycles 111 = 7 input clock cycles Rev. C | Page 34 of 44 Clock divide ratio 000 = divide by 1 001 = divide by 2 010 = divide by 3 011 = divide by 4 100 = divide by 5 101 = divide by 6 110 = divide by 7 111 = divide by 8 Nibbles are mirrored so that LSB-first or MSB-first mode is set correctly, regardless of shift mode. To control this register, all channel index bits in Register 0x05 must be set. Read only Speed grade ID differentiates devices; read only Channel Index and Transfer Registers 0x05 Open Channel index Open (global) Transfer (global) Default/ Comments 0x00 Bits set to determine which device on the chip receives next write command; local registers only Synchronously transfers data from master shift register to slave Determines various generic modes of chip operation 0x01 0x00 Read Only 0x00 Clock divide values other than 000 automatically causes duty cycle stabilizer to become active Data Sheet AD9644 Addr (Hex) 0x0D Register Name Test mode (local) Bit 7 (MSB) User test mode control 0= continuo us/repeat pattern 1 = single pattern 0x0E BIST enable (global) Offset adjust (local) Output mode 0x15 Bit 6 Open Bit 5 Reset PN long generator Bit 4 Reset PN short generat or Bit 3 Open Open Open Open Open Open Open Open Open Open Output adjust (global) Open Open Open 0x18 Input span select (global) Open Open Open 0x19 User Test Pattern 1 LSB (global) User Test Pattern 1 MSB (global) User Test Pattern 2 LSB (global) User Test Pattern 2 MSB (global) User Test Pattern 3 LSB (global) User Test Pattern 3 MSB (global) User Test Pattern 4 LSB (global) User Test Pattern 4 MSB (global) PLL Control (global) 0x10 0x14 0x1A 0x1B 0x1C 0x1D 0x1E 0x1F 0x20 0x21 Open Open Bit 0 (LSB) Bit 2 Bit 1 Output test mode 0000 = off (default) 0001 = midscale short 0010 = positive FS 0011 = negative FS 0100 = alternating checkerboard 0101 = PN long sequence 0110 = PN short sequence 0111 = one/zero word toggle 1000 = user test mode 1001 to 1110 = unused 1111 = ramp output Open BIST enable Reset BIST sequence Open Open Output format 00 = offset binary 01 = twos complement (default) 10 = gray code 11 = offset binary (local) Open Open Open Output drive level adjust 11 = 320 mV 00 = 400 mV 10 = 440 mV 01 = 500 mV Full-scale input voltage selection 01111 = 2.087 V p-p … 00001 = 1.772 V p-p 00000 = 1.75 V p-p (default) 11111 = 1.727 V p-p … 10000 = 1.383 V p-p User Test Pattern 1 [7:0] 0x00 Output invert (local) 0x01 0x00 User Test Pattern 2 [7:0] 0x00 User Test Pattern 2 [15:8] 0x00 User Test Pattern 3 [7:0] 0x00 User Test Pattern 3 [15:8] 0x00 User Test Pattern 4 [7:0] 0x00 User Test Pattern 4 [15:8] 0x00 Rev. C | Page 35 of 44 Open Open Open Full-scale input adjustment in 0.022 V steps 0x00 0x00 PLL Low encode rate enable Configures outputs and the format of the data 0x00 User Test Pattern 1 [15:8] Open Default/ Comments When this register is set, test data is used in place of normal ADC data 0x00 Offset adjust in LSBs from +31 to −32 (twos complement format) Output disable (local) Default Value (Hex) 0x00 0x00 Bit 3 must be enabled if ADC clock rate is less than 60 MSPS AD9644 Addr (Hex) 0x24 0x25 0x3A Register Name BIST signature LSB (local) BIST signature MSB (local) Sync control (global) Data Sheet Bit 7 (MSB) Bit 6 Bit 5 Bit 4 Bit 3 BIST signature[7:0] Open Clock divider next sync only Open Open Open Open 000 = default—configuration determined by other registers 001 = two converters using two links with one lane per link 010 = two converters using one link with two lanes per link 011 = two converters using one link and a single lane 100 to 111: reserved 0x00 JESD204A serial lane control 0000 = one lane per link. Link A: Lane 0 sent on Lane A, Link B: Lane 0 Sent on Lane B 0001 = one lane per link. Link A: Lane 0 sent on Lane B, Link B: Lane 0 Sent on Lane A. 0010 = two lanes per link. Link A: Lane 0, Lane 1 sent on Lane A, Lane B. Link B disabled. 0011 = two lanes per link. Link A: Lane 0, Lane 1 sent on Lane B, Lane A. Link B disabled. 0100 = two lanes per link. Link B: Lane 0, Lane 1 sent on Lane A, Lane B. Link A disabled. 0101 = two lanes per link. Link B: Lane 0, 1 sent on Lane B, Lane A. Link A disabled. 0110 to 1111: reserved Serial lane alignment Frame Serial sequence mode alignment transmit link character powered 00 = disabled insertion down 01 = enabled disable 10 = reserved 0x00 Open Open 0x60 JESD204A Link Control Register 1 (local) Open Serial tail bit enable Serial test sample enable Serial lane synchro nization enable JESD204A Link Control Register 4 (local) JESD204A device identification number (DID) (local) 0x64 Read only Open Open 0x63 0x00 Open Open JESD204A Link Control Register 3 (local) Default/ Comments Read only Open JESD204A lane assignment (global) 0x62 Default Value (Hex) 0x00 Open 0x5F JESD204A Link Control Register 2 (local) Bit 1 BIST signature[15:8] JESD204A Configuration Registers 0x5E Open JESD204A quick configure (global) 0x61 Bit 2 Bit 0 (LSB) Local DSYNC mode 00 = individual mode 01 = global mode 10 = DSYNC active mode 11 = DSYNC pin disabled Open Disable CHKSUM 11 = always on test mode Open Bypass 8b/10b encoding Clock divider sync enable Master sync buffer enable 0x00 0x00 Mirror serial output bits 0x00 Link test generation mode 000 = normal operation 001 = alternating checker board 010 = 1/0 word toggle 011 = PN sequence—long 100 = PN sequence—short 101 = user test pattern data continuous 110 = user test pattern data single 111 = ramp output Initial lane assignment sequence repeat count 0x00 DSYNC pin input inverted CMOS DSYNC input 0= LVDS 1= CMOS Link test generation input selection 00 = 16-bit data injected at sample input to the link 01 = 10-bit data injected at output of 8b/10b encoder 10 = reserved 11 = reserved Open JESD204A serial device identification (DID) number Rev. C | Page 36 of 44 Invert transmit bits 0x00 0x00 Changes settings of Address 0x5F to Address 0x60 and Address 0x6E to Address 0x72 (self clearing) Data Sheet Addr (Hex) 0x65 0x66 0x67 0x6E 0x6F 0x70 0x71 Register Name JESD204A bank identification number (BID) (local) JESD204A lane identification number (LID) for Lane 0 (local) JESD204A lane identification number (LID) for Lane 1 (local) JESD204A scrambler (SCR) and lane (L) configuration register JESD204A number of octets per frame (F) (global) JESD204A number of frames per multiframe (K) (local) JESD204A number of converters per link (M) (global) 0x72 JESD 204A ADC resolution (N) and control bits per sample (CS) (local) 0x73 JESD204A total bits per sample (N’) (global) JESD204A samples per converter (S) frame cycle (global) JESD204A HD and CF configuration (global) 0x74 0x75 AD9644 Default Value (Hex) 0x00 Bit 7 (MSB) Open Bit 6 Open Bit 5 Open Open Open Open JESD204A serial lane identification (LID) number for Lane 0 0x00 Open Open Open JESD204A serial lane identification (LID) number for Lane 1 0x01 Open Open Bit 4 Open 0x80 Lane control (global) 0 = one lane per link (L = 1) 1 = two lanes per link (L = 2) JESD204A number of octets per frame (F)—these bits are calculated based on the equation: F = M × (2 ÷ L) 0x01 Enable serial scrambler mode (SCR) (local) Open Open Open Open Open Open Open Bit 0 Bit 3 Bit 2 Bit 1 (LSB) JESD204A serial bank identification number (BID) Open Open Open JESD204A number of frames per multiframe (K) Open Open Open Default/ Comments Open Number of converters per link (M) 0 = link connected to one ADC (M = 1) 1 = link connected to two ADCs (M = 2) Read only 0x0F 0x00 Number of control bits per sample (CS) 00 = no control bits (CS = 0) 01 = one control bit (CS = 1) 10 = two control bits (CS = 2) 11 = unused Open Open Open Converter resolution (N) (read only) 0x4D Open Total bits per sample (N’) (read only) 0x0F Read only Open Open Open Samples per converter (S) frame cycle (read only) Always 1 for the AD9644 0x00 Read only Enable high density format (HD = 0, read only) Open Open Number of control words per frame clock cycle per Link (CF) – always 0 for the AD9644 (read only) 0x00 Read only Rev. C | Page 37 of 44 AD9644 Addr (Hex) 0x76 0x77 0x78 0x79 1 Register Name JESD204A serial reserved Field 1 (RES1) JESD204A serial reserved Field 2 (RES2) JESD204A checksum value (FCHK) for Lane 0 (local) JESD204A checksum value (FCHK) for lane 1 (local) Data Sheet Bit 7 (MSB) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Serial Reserved Field 1 (RES1) – these registers are available for customer use Bit 0 (LSB) Default Value (Hex) 0x00 Default/ Comments Serial Reserved Field 2 (RES2) – these registers are available for customer use 0x00 Serial checksum value for Lane 0 (FCHK) 0x00 Read only Serial checksum value for Lane 1 (FCHK) 0x00 Read only The channel index register at Address 0x05 should be set to 0x03 (default) when writing to Address 0x00. MEMORY MAP REGISTER DESCRIPTIONS 000: default—configuration determined by other registers For additional information about functions controlled in Register 0x00 to Register 0x25, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. 001: two converters using two links with one lane per link (maximum sample rate = 80 MHz or 155 MHz) Each link configuration: M = 1; N’ = 16; CF = 0; K = 16; S = 1; F = 2; L = 1; HD = 0; Sync Control (Register 0x3A) Bits[7:3]—Open Bit 2—Clock Divider Next Sync Only If the master sync buffer enable bit (Address 0x3A, Bit 0) and the clock divider sync enable bit (Address 0x3A, Bit 1) are high, Bit 2 allows the clock divider to sync to the first sync pulse it receives and to ignore the rest. The clock divider sync enable bit (Address 0x3A, Bit 1) resets after it syncs. Bit 1—Clock Divider Sync Enable Bit 1 gates the sync pulse to the clock divider. The sync signal is enabled when Bit 1 is high and Bit 0 is high. This is continuous sync mode. Bit 0—Master Sync Buffer Enable 010 = two converters using one link with two lanes per link (Maximum sample rate = 80 MHz or 155 MHz). Each link configuration: M = 2; N’ = 16; CF = 0; K = 16; S = 1; F = 2; L = 2; HD = 0; uses DSYNCA pin for synchronization. Setting this mode sets Address 0x5F = 0x02 and sets Address 0x60 = 0x14 for Link A and sets Address 0x60 = 0x01 for Link B. 011 = two converters using one link and a single lane (maximum sample rate = 78.125 MHz). Each link configuration: M = 2; N’ = 16; CF = 0; K = 8;S = 1; F = 4; L = 1; HD = 0; uses DSYNCA pin for synchronization and DOUTA for output signals. 100 to 111: reserved. JESD204A Lane Assignment (Register 0x5F) Bits[7:4]—Reserved Bit 0 must be high to enable any of the sync functions. If the sync capability is not used this bit should remain low to conserve power. Bits[3:0]—JESD204A Serial Lane Control These bits set the lane usage. See Figure 62. JESD204A Quick Configure (Register 0x5E) Bits[7:3]—Reserved 0000: one lane per link. Link A: Lane 0 sent on Lane A, Link B: Lane 0 sent on Lane B. Bits[2:0]—Register Quick Configuration Writes to Bits[2:0] of this register configure the part for the most popular modes of operation for the JESD204A link. The intent of this register is to simplify the part setup for typical serial link operation modes. Writing values other than 0x0 to this register causes registers throughout the JESD204A memory map to be updated. Once these registers have been written the affected JESD204A configuration register reads back with their new values and can be updated. These bits are self clearing and always read back as 0b000. 0001: one lane per link. Link A: Lane 0 sent on Lane B, Link B: Lane 0 sent on Lane A. 0010: two lanes per link. Link A: Lane 0, one sent on Lane A, Link B disabled. 0011: two lanes per link. Link A: Lane 0, one sent on Lane B, Lane A. Link B disabled. 0100: two lanes per link. Link B: Lane 0, one sent on Lane A, Lane B. Link A disabled. 0101: two lanes per link. Link B: Lane 0, one sent on Lane B, Lane A. Link A disabled. 0110 to 1111: reserved for future use. Rev. C | Page 38 of 44 Data Sheet AD9644 JESD204A Link Control Register 1 (Register 0x60) Bit 7—Reserved Bit 3—Open Bit 2—Bypass 8b/10b Encoding Bit 6—Serial Tail Bit Enable If this bit is set, the unused tail bits are padded with a pseudo random number sequence from a 31-bit LFSR (see JESD204A 5.1.4). Bit 5—Serial Test Sample Enable If this bit is set, JESD204A test samples are enabled—transport layer test sample sequence (as specified in JESD204A section 5.1.6.2) is sent on all link lanes. Bit 4—Serial Lane Synchronization Enable If this bit is set, lane synchronization is enabled. Both sides perform lane sync. Frame alignment character insertion uses either /K28.3/ or /K28.7/ control characters (see JESD204A 5.3.3.4). If this bit is set the 8b/10b encoding is bypassed and the most significant bits are set to 0. Bit 1—Invert Transmit Bits Setting this bit inverts the 10 serial output bits. This effectively inverts the output signals. Bit 0—Mirror Serial Output Bits Setting this bit reverses the order of the 10b outputs. JESD204A Link Control Register 3 (Register 0x62) Bit 7—Disable CHKSUM Setting this bit high disables the CHKSUM configuration parameter (for testing purposes only). Bit 6—Open Bits[3:2]—Serial Lane Alignment Sequence Mode Bits[5:4]—Link Test Generation Input Selection 00: initial lane alignment sequence disabled. 00: 16-bit test generation data injected at sample input to the link. 01: initial lane alignment sequence enabled. 10: reserved. 11: initial lane alignment sequence always on test mode— JESD204A data link layer test mode where repeated lane alignment sequence is sent on all lanes. 01: 10-bit test generation data injected at output of 8b/10b encoder (at input to PHY). 10: reserved. 11: reserved. Bit 1—Frame Alignment Character Insertion Disable Bit 3—Open If Bit 1 is set, the frame alignment character insertion is disabled per JESD204A section 5.3.3.4. Bits[2:0]—Link Test Generation Mode Bit 0—Serial Transmit Link Powered Down 001: alternating checker board. If Bit 0 is set high, the serial transmit link is held in reset with its clock gated off. The JESD204A transmitter should be powered down when changing any of the link configuration bits. 010: 1/0 word toggle. 000: normal operation (test mode disabled). JESD204A Link Control Register 2 (Register 0x61) Bits[7:6]—Local DSYNC Mode 00: individual/separate mode. Each link is controlled by a separate DSYNC pin that independently controls code group synchronization. 01: global mode. Any DSYNC signal causes the link to begin code group synchronization. 10: sync active mode. DSYNC signal is active—force code group synchronization. 11: DSYNC pin disabled. If this bit is set, the DSYNC pin of the link is inverted (active high). 0: LVDS differential pair DSYNC input (default) 1: CMOS single ended DSYNC input 100: PN sequence—short. 101: continuous/repeat user test mode—most significant bits from user pattern (1, 2, 3, 4) placed on the output for 1 clock cycle and then repeat. (output user pattern 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4…). 110: single user test mode—most significant bits from user pattern (1, 2, 3, 4) placed on the output for 1 clock cycle and then output all zeros. (output user pattern 1, 2, 3, 4, then output all zeros). 111: ramp output. JESD204A Link Control Register 4 (Register 0x63) Bits[7:0]—Initial Lane Alignment Sequence Repeat Count Bit 5—DSYNC Pin Input Inverted Bit 4—CMOS DSYNC Input 011: PN sequence—long. Specifies the number of times the initial lane alignment sequence (ILAS) is repeated. If 0 is programmed the ILAS does not repeat. If 1 is programmed the ILAS repeat one time and so on. See Register 0x60, Bits[3:2] to enable the ILAS and for a test mode to continuously enable the initial lane alignment sequence. Rev. C | Page 39 of 44 AD9644 Data Sheet JESD204A Device Identification Number (DID) (Register 0x64) Bits[7:0]—Serial Device Identification (DID) Number JESD204A Number of Converters Per Link (M) (Register 0x71) Bits[7:1]—Reserved JESD204A Bank Identification Number (BID) (Register 0x65) Bits[7:4]—Open Bit 0—Number of Converters per Link per Device (M). 0: link connected to one ADC. Only primary input used (M = 1). Bits[3:0]—Serial Bank Identification (DID) Number 1: link connected to two ADCs. Primary and secondary inputs used (M = 2). JESD204A Lane Identification Number (LID) for Lane 0 (Register 0x66) Bits[7:5]—Open JESD204A ADC Resolution (N) and Control Bits Per Sample (CS) (Register 0x72) Bits[7:6]—Number of Control Bits per Sample (CS) Bits[4:0]—Serial Lane Identification (LID) Number for Lane 0. JESD204A Lane Identification Number (LID) for Lane 1 (Register 0x67) Bits[7:5]—Open Bits[4:0]—Serial Lane Identification (LID) Number for Lane 1. JESD204A Scrambler (SCR) and Lane Configuration Registers (Register 0x6E) Bit 7—Enable Serial Scrambler Mode 10: two control bits sent per sample—overflow/underflow bits enabled (CS = 2). 11: unused. Bit 5—Open Read only bits showing the converter resolution (reads back 13 (0xD) for 14-bit resolution). JESD204A Total Bits Per Sample (N’) (Register 0x73) Bits[7:5]—Open Bits[6:1]—Open Bit[0]—Serial Lane Control. Bits[4:0]—Total Number of Bits per Sample (N’) 00000: one lane per link (L = 1). Read only bits showing the total number of bits per sample—1 (reads back 15 (0xF) for 16 bits per sample). 00001: two lanes per link (L = 2). 00010: 11111—reserved. JESD204A Samples Per Converter (S) Frame Cycle (Register 0x74) Bits[7:5]—Open JESD204A Number of Octets Per Frame (F) (Register 0x6F—Read Only) Bits[7:0]—Number of Octets per Frame (F) The readback from this register is calculated from the following equation: F = (M × 2)/L F = 2, with M = 1 and L = 1 01: one control bits sent per sample—overrange bit enabled. (CS = 1). Bits[4:0]—Converter Resolution (N) Setting this bit high enables the scrambler (SCR = 1). Valid values for F for the AD9644 are: 00: no control bits sent per sample (CS = 0). Bits[4:0]—Samples per Converter Frame Cycle (S) Read only bits showing the number of samples per converter frame cycle −1 (reads back 0 (0x0) for 1 sample per converter frame). F = 4, with M = 2 and L = 1 JESD204A HD and CF Configuration (Register 0x75) Bit 7—Enable High Density Format (Read Only) F = 2, with M = 2 and L = 2 Read only bit—always 0 in the AD9644. JESD204A Number of Frames Per Multiframe (Register 0x70) Bits[7:5]—Reserved Bits[6:5]—Reserved Bits[4:0]—Number of Frames per Multiframe (K). Bits[4:0]—Number of Control Words per Frame Clock Cycle per Link (CF) Read only bits—reads back 0x0 for the AD9644. Rev. C | Page 40 of 44 Data Sheet JESD204A Serial Reserved Field 1 (Register 0x76) Bits[7:0]—Serial Reserved Field 1 (RES1) This read/write register is available for customer use. JESD204A Serial Reserved Field 2 (Register 0x77) Bits[7:0]—Serial Reserved Field 2 (RES2) This read/write register is available for customer use. AD9644 JESD204A Serial Checksum Value for Lane 0 (Register 0x78) Bits[7:0]—Serial Checksum Value for Lane 0 This read only register is automatically calculated for each lane. Sum (all link configuration parameters for Lane 0) mode 256. JESD204A Serial Checksum Value for Lane 1 (Register 0x79) Bits[7:0]—Serial Checksum Value for Lane 1 This read only register is automatically calculated for each lane. Sum (all link configuration parameters for Lane 1) mode 256. Rev. C | Page 41 of 44 AD9644 Data Sheet APPLICATIONS INFORMATION DESIGN GUIDELINES Before starting design and layout of the AD9644 as a system, it is recommended that the designer become familiar with these guidelines, which discuss the special circuit connections and layout requirements that are needed for certain pins. Power and Ground Recommendations When connecting power to the AD9644, it is recommended that two separate 1.8 V supplies be used. Use one supply for analog (AVDD); use a separate supply for the digital outputs (DRVDD). For both AVDD and DRVDD several different decoupling capacitors should be used to cover both high and low frequencies. Place these capacitors close to the point of entry at the PCB level and close to the pins of the part, with minimal trace length. A single PCB ground plane should be sufficient when using the AD9644. With proper decoupling and smart partitioning of the PCB analog, digital, and clock sections, optimum performance is easily achieved. Exposed Paddle Thermal Heat Slug Recommendations It is mandatory that the exposed paddle on the underside of the ADC be connected to analog ground (AGND) to achieve the best electrical and thermal performance. A continuous, exposed (no solder mask) copper plane on the PCB should mate to the AD9644 exposed paddle, Pin 0. The copper plane should have several vias to achieve the lowest possible resistive thermal path for heat dissipation to flow through the bottom of the PCB. These vias should be filled or plugged to prevent solder wicking through the vias, which can compromise the connection. To maximize the coverage and adhesion between the ADC and the PCB, a silkscreen should be overlaid to partition the continuous plane on the PCB into several uniform sections. This provides several tie points between the ADC and the PCB during the reflow process. Using one continuous plane with no partitions guarantees only one tie point between the ADC and the PCB. For detailed information about packaging and 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), at www.analog.com. VCMA and VCMB The VCMA and VCMB pins should be decoupled to ground with a 0.1 μF capacitor, as shown in Figure 50. SPI Port The SPI port should not be active during periods when the full dynamic performance of the converter is required. Because the SCLK, CSB, and SDIO signals 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 AD9644 to keep these signals from transitioning at the converter inputs during critical sampling periods. Rev. C | Page 42 of 44 Data Sheet AD9644 OUTLINE DIMENSIONS 0.30 0.23 0.18 0.60 MAX 0.60 MAX 37 36 PIN 1 INDICATOR 6.85 6.75 SQ 6.65 48 0.50 REF 1.00 0.85 0.80 0.80 MAX 0.65 TYP 12° MAX 13 12 0.22 MIN 5.50 REF 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF SEATING PLANE 5.50 SQ 5.45 (BOTTOM VIEW) 0.50 0.40 0.30 PIN 1 INDICATOR *5.55 EXPOSED PAD 25 24 TOP VIEW 1 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-VKKD-2 WITH EXCEPTION TO EXPOSED PAD DIMENSION. 02-23-2010-C 7.10 7.00 SQ 6.90 Figure 72. 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 7 mm × 7 mm Body, Very Thin Quad (CP-48-8) Dimensions shown in millimeters ORDERING GUIDE Model 1 AD9644BCPZ-80 AD9644BCPZRL7-80 AD9644CCPZ-80 AD9644CCPZRL7-80 AD9644BCPZ-155 AD9644BCPZRL7-155 AD9644-80KITZ AD9644-155KITZ 1F1F 1 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 Package Description 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] Evaluation Board Evaluation Board Z = RoHS Compliant Part. Rev. C | Page 43 of 44 Package Option CP-48-8 CP-48-8 CP-48-8 CP-48-8 CP-48-8 CP-48-8 AD9644 Data Sheet NOTES ©2010–2012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09180-0-1/12(C) Rev. C | Page 44 of 44