16-Bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS, 1.8 V Analog-to-Digital Converter AD9266 Data Sheet FEATURES FUNCTIONAL BLOCK DIAGRAM 1.8 V analog supply operation 1.8 V to 3.3 V output supply SNR 77.6 dBFS at 9.7 MHz input 71.1 dBFS at 200 MHz input SFDR 93 dBc at 9.7 MHz input 80 dBc at 200 MHz input Low power 56 mW at 20 MSPS 113 mW at 80 MSPS Differential input with 700 MHz bandwidth On-chip voltage reference and sample-and-hold circuit 2 V p-p differential analog input DNL = −0.6/+1.1 LSB Interleaved data output for reduced pin-count interface Serial port control options Offset binary, Gray code, or twos complement data format Optional clock duty cycle stabilizer Integer 1-to-8 input clock divider Built-in selectable digital test pattern generation Energy-saving power-down modes Data clock output (DCO) with programmable clock and data alignment AVDD APPLICATIONS Communications Diversity radio systems Multimode digital receivers GSM, EDGE, W-CDMA, LTE, CDMA2000, WiMAX, TD-SCDMA Smart antenna systems Battery-powered instruments Handheld scope meters Portable medical imaging Ultrasound Radar/LIDAR PET/SPECT imaging Rev. B SDIO SCLK CSB AGND RBIAS SPI AD9266 PROGRAMMING DATA VIN+ ADC CORE VIN– CMOS OUTPUT BUFFER VCM DRVDD OR D15_D14 8 VREF D1_D0 DCO SENSE REF SELECT DUTY CYCLE STABILIZER MODE CONTROLS PDWN DFS MODE CLK+ CLK– 08678-001 DIVIDE 1 TO 8 Figure 1. PRODUCT HIGHLIGHTS 1. 2. 3. 4. The AD9266 operates from a single 1.8 V analog power supply and features a separate digital output driver supply to accommodate 1.8 V to 3.3 V logic families. The sample-and-hold circuit maintains excellent performance for input frequencies up to 200 MHz and is designed for low cost, low power, and ease of use. A standard serial port interface supports various product features and functions, such as data output formatting, internal clock divider, power-down, DCO and data output (D15_D14 to D1_D0) timing and offset adjustments, and voltage reference modes. The AD9266 is packaged in a 32-lead RoHS-compliant LFCSP that is pin compatible with the AD9609 10-bit ADC, the AD9629 12-bit ADC, and the AD9649 14-bit ADC, enabling a simple migration path between 10-bit and 16-bit converters sampling from 20 MSPS to 80 MSPS. Document Feedback 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 ©2010–2016 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com AD9266* PRODUCT PAGE QUICK LINKS Last Content Update: 02/23/2017 COMPARABLE PARTS TOOLS AND SIMULATIONS View a parametric search of comparable parts. • Visual Analog • AD9266 IBIS Model EVALUATION KITS • AD9269LFCSP/AD9266LFCSP S Parameter • AD9266 Evaluation Board REFERENCE MATERIALS DOCUMENTATION Solutions Bulletins & Brochures Application Notes • AN-1142: Techniques for High Speed ADC PCB Layout • Analog-to-Digital Converter and Drivers ICs Solutions Bulletin, Volume 10, Issue 2 • AN-586: LVDS Outputs for High Speed A/D Converters Technical Articles • AN-742: Frequency Domain Response of SwitchedCapacitor ADCs • Improve The Design Of Your Passive Wideband ADC Front-End Network • AN-807: Multicarrier WCDMA Feasibility • MS-2210: Designing Power Supplies for High Speed ADC • AN-808: Multicarrier CDMA2000 Feasibility • AN-812: MicroController-Based Serial Port Interface (SPI) Boot Circuit DESIGN RESOURCES • AD9266 Material Declaration • AN-827: A Resonant Approach to Interfacing Amplifiers to Switched-Capacitor ADCs • PCN-PDN Information • AN-878: High Speed ADC SPI Control Software • Symbols and Footprints • AN-935: Designing an ADC Transformer-Coupled Front End Data Sheet • Quality And Reliability DISCUSSIONS View all AD9266 EngineerZone Discussions. • AD9266-DSCC: Military Data Sheet • AD9266-EP: Enhanced Product Data Sheet SAMPLE AND BUY • AD9266: 16-Bit, 20/40/65/80 MSPS, 1.8 V Analog-to-Digital Converter Data Sheet Visit the product page to see pricing options. 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AD9266 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Voltage Reference ....................................................................... 19 Applications ....................................................................................... 1 Clock Input Considerations ...................................................... 20 Functional Block Diagram .............................................................. 1 Power Dissipation and Standby Mode .................................... 22 Product Highlights ........................................................................... 1 Digital Outputs ........................................................................... 22 Revision History ............................................................................... 2 Timing ......................................................................................... 23 General Description ......................................................................... 3 Output Test ...................................................................................... 24 Specifications..................................................................................... 4 Output Test Modes ..................................................................... 24 DC Specifications ......................................................................... 4 Serial Port Interface (SPI) .............................................................. 25 AC Specifications.......................................................................... 5 Configuration Using the SPI ..................................................... 25 Digital Specifications ................................................................... 6 Hardware Interface..................................................................... 26 Switching Specifications .............................................................. 7 Configuration Without the SPI ................................................ 26 Timing Specifications .................................................................. 8 SPI Accessible Features .............................................................. 26 Absolute Maximum Ratings............................................................ 9 Memory Map .................................................................................. 27 Thermal Characteristics .............................................................. 9 Reading the Memory Map Register Table............................... 27 ESD Caution .................................................................................. 9 Open Locations .......................................................................... 27 Pin Configuration and Function Descriptions ........................... 10 Default Values ............................................................................. 27 Typical Performance Characteristics ........................................... 11 Memory Map Register Table ..................................................... 28 AD9266-80 .................................................................................. 11 Memory Map Register Descriptions ........................................ 30 AD9266-65 .................................................................................. 13 Applications Information .............................................................. 31 AD9266-40 .................................................................................. 14 Design Guidelines ...................................................................... 31 AD9266-20 .................................................................................. 15 Outline Dimensions ....................................................................... 32 Equivalent Circuits ......................................................................... 16 Ordering Guide .......................................................................... 32 Theory of Operation ...................................................................... 17 Analog Input Considerations.................................................... 17 REVISION HISTORY 3/16—Rev. A to Rev. B Change to Product Highlights Section .......................................... 1 Changes to Pipeline Delay (Latency) Parameter, Table 4 ............ 7 Changes to Figure 3 and Table 8 ................................................... 10 Changes to Clock Input Options Section .................................... 20 Changes to Data Clock Output Section ....................................... 23 6/12—Rev. 0 to Rev. A Changes to Table 1 ............................................................................ 4 Changes to Table 4 ............................................................................ 7 Changed Built-In Self-Test (BIST) and Output Test Section to Output Test Section ........................................................................ 24 Changes to Output Test Section; Deleted Built-In Self-Test (BIST) Section ................................................................................. 24 Changes to Table 16 ........................................................................ 28 4/10—Revision 0: Initial Version Rev. B | Page 2 of 32 Data Sheet AD9266 GENERAL DESCRIPTION The AD9266 is a monolithic, single-channel 1.8 V supply, 16-bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS analog-to-digital converter (ADC). It features a high performance sample-andhold circuit and on-chip voltage reference. A differential clock input with a selectable internal 1-to-8 divide ratio controls all internal conversion cycles. An optional duty cycle stabilizer (DCS) compensates for wide variations in the clock duty cycle while maintaining excellent overall ADC performance. The product uses multistage differential pipeline architecture with output error correction logic to provide 16-bit accuracy at 80 MSPS data rates and to guarantee no missing codes over the full operating temperature range. The interleaved digital output data is presented in offset binary, gray code, or twos complement format. A DCO is provided to ensure proper latch timing with receiving logic. Both 1.8 V and 3.3 V CMOS levels are supported. The ADC contains several features designed to maximize flexibility and minimize system cost, such as programmable clock and data alignment and programmable digital test pattern generation. The available digital test patterns include built-in deterministic and pseudorandom patterns, along with custom user-defined test patterns entered via the serial port interface (SPI). The AD9266 is available in a 32-lead RoHS-compliant LFCSP and is specified over the industrial temperature range (−40°C to +85°C). Rev. B | Page 3 of 32 AD9266 Data Sheet SPECIFICATIONS DC SPECIFICATIONS AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. Table 1. Parameter RESOLUTION ACCURACY No Missing Codes Offset Error Gain Error 1 Differential Nonlinearity (DNL) 2 Integral Nonlinearity (INL)2 TEMPERATURE DRIFT Offset Error INTERNAL VOLTAGE REFERENCE Output Voltage (1 V Mode) Load Regulation Error at 1.0 mA INPUT-REFERRED NOISE VREF = 1.0 V ANALOG INPUT Input Span, VREF = 1.0 V Input Capacitance 3 Input Common-Mode Voltage Input Common-Mode Range REFERENCE INPUT RESISTANCE POWER SUPPLIES Supply Voltage AVDD DRVDD Supply Current IAVDD2 IDRVDD2 (1.8 V) IDRVDD2 (3.3 V) POWER CONSUMPTION DC Input Sine Wave Input2 (DRVDD = 1.8 V) Sine Wave Input2 (DRVDD = 3.3 V) Standby Power 4 Power-Down Power Temp Full AD9266-20/AD9266-40 Min Typ Max 16 Min 16 AD9266-65 Typ Max Min 16 AD9266-80 Typ Max Unit Bits Full Full Full Full Guaranteed +0.05 ±0.30 −2.5/−2.0 −0.9/+1.2 Guaranteed +0.05 ±0.30 −1.0 −0.9/+1.7 Guaranteed +0.05 ±0.30 +1.0 −0.9/+1.7 25°C Full −0.5/+0.6 −0.5/+1.0 −0.6/+1.1 25°C ±1.8 ±2.4 ±3.5 LSB Full ±2 ±2 ±2 ppm/°C Full Full ±5.5 0.983 0.995 2 ±6.5 1.007 0.983 0.995 2 1.007 ±6.2 0.983 0.995 2 1.007 % FSR % FSR LSB LSB LSB V mV 25°C 2.8 2.8 2.8 LSB rms Full Full Full 2 6.5 0.9 2 6.5 0.9 2 6.5 0.9 V p-p pF V Full 0.5 Full Full Full 1.3 0.5 7.5 1.7 1.7 1.3 0.5 7.5 1.7 1.7 1.3 7.5 1.9 3.6 54.5 57.6 1.9 3.6 Full 31.4/40.7 33.2/42.5 Full 1.7/3.3 5.2 6.3 mA Full 3.0/5.9 9.3 11.6 mA Full Full 57/73 60/79 Full 66/93 129 151 mW Full Full 40 0.5 44 0.5 44 0.5 mW mW 98 107 113 1.7 1.7 kΩ 1.8 63/82 1.8 V 1.8 1.9 3.6 V V 62.5 65.7 mA 113 124 Measured with 1.0 V external reference. Measured with a 10 MHz input frequency at rated sample rate, full-scale sine wave, with approximately 5 pF loading on each output bit. 3 Input capacitance refers to the effective capacitance between the differential inputs. 4 Standby power is measured with a dc input and the CLK active. 1 2 Rev. B | Page 4 of 32 130 mW mW Data Sheet AD9266 AC SPECIFICATIONS AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. Table 2. Parameter 1 SIGNAL-TO-NOISE RATIO (SNR) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 200 MHz SIGNAL-TO-NOISE-AND-DISTORTION (SINAD) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 200 MHz EFFECTIVE NUMBER OF BITS (ENOB) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 200 MHz WORST SECOND OR THIRD HARMONIC fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 200 MHz SPURIOUS-FREE DYNAMIC RANGE (SFDR) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 200 MHz WORST OTHER (HARMONIC OR SPUR) fIN = 9.7 MHz fIN = 30.5 MHz fIN = 70 MHz fIN = 200 MHz TWO-TONE SFDR fIN = 30.5 MHz (−7 dBFS), 32.5 MHz (−7 dBFS) ANALOG INPUT BANDWIDTH 1 Temp 25°C 25°C Full 25°C Full 25°C 25°C 25°C Full 25°C Full 25°C AD9266-20/AD9266-40 Min Typ Max Min AD9266-65 Typ Max 78.2 77.6 AD9266-80 Min Typ Max 77.9 77.5 76.7 77.6 77.3 dBFS dBFS dBFS dBFS dBFS dBFS 76.6 75.8/76.4 76.6 76.6 75.5 72.1 78.0 77.5 77.7 77.3 76.2 77.4 77.1 69.4 dBFS dBFS dBFS dBFS dBFS dBFS 76.2 75.7/76.3 76.5 Unit 76.6 75.5 25°C 25°C 25°C 25°C 12.7 12.6 12.3/12.4 12.6 12.5 12.4 12.6 12.5 12.4 11.2 Bits Bits Bits Bits 25°C 25°C Full 25°C Full 25°C −97 −96/−93 −96 −94 −95 −93 dBc dBc dBc dBc dBc dBc 25°C 25°C Full 25°C Full 25°C 95 93 −80 −80 −97/−95 −98 −95 −80 −80 95 92 80 94 92 dBc dBc dBc dBc dBc dBc 80 93 95 93 80 80 25°C 25°C Full 25°C Full 25°C −102 −102 25°C 25°C 90 700 −101 −101 −89 −101 −99 −98 −86 dBc dBc dBc dBc dBc dBc 90 700 dBc MHz −89 −100 −98 −89 90 700 See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions. Rev. B | Page 5 of 32 AD9266 Data Sheet DIGITAL SPECIFICATIONS AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. Table 3. Parameter DIFFERENTIAL CLOCK INPUTS (CLK+, CLK−) Logic Compliance Internal Common-Mode Bias Differential Input Voltage Input Voltage Range High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUTS (SCLK/DFS, MODE, SDIO/PDWN) 1 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUTS (CSB) 2 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance DIGITAL OUTPUTS DRVDD = 3.3 V High Level Output Voltage, IOH = 50 µA High Level Output Voltage, IOH = 0.5 mA Low Level Output Voltage, IOL = 1.6 mA Low Level Output Voltage, IOL = 50 µA DRVDD = 1.8 V High Level Output Voltage, IOH = 50 µA High Level Output Voltage, IOH = 0.5 mA Low Level Output Voltage, IOL = 1.6 mA Low Level Output Voltage, IOL = 50 µA 1 2 Temp Full Full Full Full Full Full Full Min AD9266-20/AD9266-40/AD9266-65/AD9266-80 Typ Max CMOS/LVDS/LVPECL 0.9 0.2 GND − 0.3 −10 −10 8 Full Full Full Full Full Full 1.2 0 −50 −10 Full Full Full Full Full Full 1.2 0 −10 40 Full Full Full Full 3.29 3.25 Full Full Full Full 1.79 1.75 10 4 3.6 AVDD + 0.2 +10 +10 12 V V µA µA kΩ pF DRVDD + 0.3 0.8 +10 135 V V µA µA kΩ pF 26 2 Rev. B | Page 6 of 32 V V p-p V µA µA kΩ pF DRVDD + 0.3 0.8 −75 +10 30 2 Internal 30 kΩ pull-down. Internal 30 kΩ pull-up. Unit 0.2 0.05 V V V V 0.2 0.05 V V V V Data Sheet AD9266 SWITCHING SPECIFICATIONS AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. Table 4. Parameter CLOCK INPUT PARAMETERS Input Clock Rate Conversion Rate1 CLK Period—Divide-by-1 Mode (tCLK) CLK Pulse Width High (tCH) Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) DATA OUTPUT PARAMETERS Data Propagation Delay (tPD) DCO Propagation Delay (tDCO) DCO to Data Skew (tSKEW) Pipeline Delay (Latency) Wake-Up Time2 Standby OUT-OF-RANGE RECOVERY TIME 2 AD9266-20/AD9266-40 Min Typ Max Full Full Full 3 50/25 80/320 20/40 AD9266-65 Typ Max 1.84 1.86 −0.53 3 3 0.1 8 350 600/400 2 520 65 3 15.38 25.0/12.5 1.0 0.1 Full Full Full Full Full Full Full Full Full Min Min AD9266-80 Typ Max 3 12.5 7.69 1.0 0.1 3.90 4.04 0.72 1.84 1.86 −0.53 3 3 0.1 8 350 300 2 625 80 MHz MSPS ns ns ns ps rms 3.90 4.04 0.72 ns ns ns Cycles μs ns Cycles 6.25 1.0 0.1 3.90 4.04 0.72 1.84 1.86 −0.53 3 3 0.1 8 350 260 2 Unit Conversion rate is the clock rate after the CLK divider. Wake-up time is dependent on the value of the decoupling capacitors. tA N–1 N N+6 N+1 N+7 N+5 VIN N+8 N+2 tCLK N+3 CLK+ CLK– tDCO DCO tSKEW tSKEW D1_D0 D1N–9 D0N–9 D1N–8 D0 N–8 D1N–7 D0N–7 D1N–6 D0 N–6 D15 N–9 D14 N–9 D15N–8 D14 N–8 D15N–7 D14 N–7 D15N–6 D14 N–6 D1 N–5 D0N–5 D1N–4 D0N–4 tPD D15_D14 D15 N–5 D14 N–5 Figure 2. CMOS Output Data Timing Rev. B | Page 7 of 32 D15 N–4 D14 N–4 08678-002 1 Temp AD9266 Data Sheet TIMING SPECIFICATIONS Table 5. Parameter SPI TIMING REQUIREMENTS tDS tDH tCLK tS tH tHIGH tLOW tEN_SDIO tDIS_SDIO Test Conditions/Comments Min 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 2 40 2 2 10 10 10 ns ns ns ns ns ns ns ns 10 ns Rev. B | Page 8 of 32 Typ Max Unit Data Sheet AD9266 ABSOLUTE MAXIMUM RATINGS THERMAL CHARACTERISTICS Table 6. Parameter AVDD to AGND DRVDD to AGND VIN+, VIN− to AGND CLK+, CLK− to AGND VREF to AGND SENSE to AGND VCM to AGND RBIAS to AGND CSB to AGND SCLK/DFS to AGND SDIO/PDWN to AGND MODE/OR to AGND D1_D0 Through D15_D14 to AGND DCO to AGND 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 +3.9 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 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 + 0.3 V −0.3 V to DRVDD + 0.3 V −0.3 V to DRVDD + 0.3 V −0.3 V to DRVDD + 0.3 V −0.3 V to DRVDD + 0.3 V −0.3 V to DRVDD + 0.3 V −40°C to +85°C 150°C −65°C to +150°C Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. The exposed paddle is the only ground connection for the chip. The exposed paddle must be soldered to the AGND plane of the user’s circuit board. Soldering the exposed paddle to the user’s board also increases the reliability of the solder joints and maximizes the thermal capability of the package. Table 7. Thermal Resistance Package Type 32-Lead LFCSP, 5 mm × 5 mm Airflow Velocity (m/sec) 0 θJA1, 2 37.1 1.0 2.5 32.4 29.1 θJC1, 3 3.1 θJB1, 4 20.7 ΨJT1, 2 0.3 Unit °C/W 0.5 0.8 °C/W °C/W Per JEDEC 51-7, plus JEDEC 51-5 2S2P test board. Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air). 3 Per 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 in 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 the θJA. ESD CAUTION Rev. B | Page 9 of 32 AD9266 Data Sheet 32 31 30 29 28 27 26 25 AVDD VIN+ VIN– AVDD RBIAS VCM SENSE VREF PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 1 2 3 4 5 6 7 8 AD9266 TOP VIEW (Not to Scale) 24 23 22 21 20 19 18 17 AVDD MODE/OR DCO (MSB) D15_D14 D13_D12 D11_D10 D9_D8 D7_D6 NOTES 1. DNC = DO NOT CONNECT. 2. THE EXPOSED PADDLE IS THE ONLY GROUND CONNECTION ON THE DEVICE. IT MUST BE SOLDERED TO THE ANALOG GROUND OF THE PCB TO ENSURE PROPER FUNCTIONALITY, HEAT DISSIPATION, NOISE, AND MECHANICAL STRENGTH. 08678-003 DNC DNC DNC DNC DRVDD D1_D0 (LSB) D3_D2 D5_D4 9 10 11 12 13 14 15 16 CLK+ CLK– AVDD CSB SCLK/DFS SDIO/PDWN DNC DNC Figure 3. Pin Configuration Table 8. Pin Function Descriptions Pin No. 0 Mnemonic EPAD 1, 2 3, 24, 29, 32 4 5 CLK+, CLK− AVDD CSB SCLK/DFS 6 SDIO/PDWN 7 to 12 14 to 21 13 22 23 DNC D1_D0 (LSB) to (MSB) D15_D14 DRVDD DCO MODE/OR 25 26 27 28 30, 31 VREF SENSE VCM RBIAS VIN−, VIN+ Description Exposed Paddle. The exposed paddle is the only ground connection on the device. It must be soldered to the analog ground of the PCB to ensure proper functionality, heat dissipation, noise, and mechanical strength. Differential Encode Clock for PECL, LVDS, or 1.8 V CMOS Inputs. 1.8 V Supply Pin for ADC Core Domain. SPI Chip Select. Active low enable, 30 kΩ internal pull-up. SPI Clock Input in SPI Mode (SCLK). 30 kΩ internal pull-down. Data Format Select in Non-SPI Mode (DFS). Static control of data output format. 30 kΩ internal pull-down. DFS high = twos complement output; DFS low = offset binary output. SPI Data Input/Output (SDIO). Bidirectional SPI data I/O with 30 kΩ internal pull-down. Non-SPI Mode Power-Down (PDWN). Static control of chip power-down with 30 kΩ internal pulldown. See Table 14 for details. Do Not Connect. ADC Digital Outputs. 1.8 V to 3.3 V Supply Pin for Output Driver Domain. Data Clock Digital Output. Chip Mode Select Input (MODE)/Out-of-Range Digital Output in SPI Mode (OR). Default = out-of-range (OR) digital output (SPI Register 0x2A, Bit 0 = 1). Option = chip mode select input (SPI Register 0x2A, Bit 0 = 0). Chip power-down (SPI Register 0x08, Bits[7:5] = 100b). Chip standby (SPI Register 0x08, Bits[7:5] = 101b). Normal operation, output disabled (SPI Register 0x08, Bits[7:5] = 110b). Normal operation, output enabled (SPI Register 0x08, Bits[7:5] = 111b). Out-of-range (OR) digital output only in non-SPI mode. 1.0 V Voltage Reference Input/Output. See Table 10. Reference Mode Selection. See Table 10. Analog Output Voltage at Mid AVDD Supply. Sets common mode of the analog inputs. Set Analog Current Bias. Connect to 10 kΩ (1% tolerance) resistor to ground. ADC Analog Inputs. Rev. B | Page 10 of 32 Data Sheet AD9266 TYPICAL PERFORMANCE CHARACTERISTICS AD9266-80 AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. 0 0 80MSPS 9.7MHz @ –1dBFS SNR = 76.8dB (77.8dBFS) SFDR = 94.3dBc –40 –60 –80 –100 –120 –60 –80 –100 10 15 20 25 30 35 40 FREQUENCY (MHz) –140 0 5 10 15 20 25 30 35 40 FREQUENCY (MHz) Figure 4. AD9266-80 Single-Tone FFT with fIN = 9.7 MHz 08678-034 5 08678-033 0 Figure 7. AD9266-80 Single-Tone FFT with fIN = 30.6 MHz 0 0 80MSPS 69MHz @ –1dBFS SNR = 75.1dB (76.1dBFS) SFDR = 89.5dBc –20 80MSPS 210MHz @ –1dBFS SNR = 70dB (71dBFS) SFDR = 79.7dBc –20 –40 AMPLITUDE (dBFS) –60 –80 –100 –120 –40 –60 –80 –100 0 5 10 15 20 25 30 35 FREQUENCY (MHz) 40 –140 08678-035 –140 0 15 20 25 30 35 40 Figure 8. AD9266-80 Single-Tone FFT with fIN = 210 MHz 0 10 80MSPS 28.3MHz @ –7dBFS 30.6MHz @ –7dBFS SFDR = 89.5dBc (96.5dBFS) –10 SFDR (dBc) SFDR/IMD3 (dBc/dBFS) –30 10 FREQUENCY (MHz) Figure 5. AD9266-80 Single-Tone FFT with fIN = 69 MHz –15 5 08678-036 –120 –45 –60 –75 2F1 + F2 2F2 + F1 –90 F2 – F1 –105 F1 + F2 2F2 – F1 2F1 – F2 –30 IMD3 (dBc) –50 –70 SFDR (dBFS) –90 –110 –120 IMD3 (dBFS) 4 8 12 16 20 24 28 FREQUENCY (MHz) 32 36 –130 –95 08678-053 –135 Figure 6. AD9266-80 Two-Tone FFT with fIN1 = 28.3 MHz and fIN2 = 30.6 MHz –85 –75 –65 –55 –45 –35 INPUT AMPLITUDE (dBFS) –25 –15 08678-054 AMPLITUDE (dBFS) –40 –120 –140 AMPLITUDE (dBFS) 80MSPS 30.6MHz @ –1dBFS SNR = 76.5dB (77.5dBFS) SFDR = 85.7dBc –20 AMPLITUDE (dBFS) AMPLITUDE (dBFS) –20 Figure 9. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 28.3 MHz and fIN2 = 30.6 MHz Rev. B | Page 11 of 32 AD9266 Data Sheet AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. 100 1.5 SFDR (dBc) 90 1.0 70 SNR (dBFS) DNL ERROR (LSB) SNR/SFDR (dBFS/dBc) 80 60 50 40 30 20 0.5 0 –0.5 –1.0 0 50 100 150 INPUT FREQUENCY (MHz) 200 –1.5 08678-057 0 0 Figure 10. AD9266-80 SNR/SFDR vs. Input Frequency (AIN) with 2 V p-p Full Scale 32,768 OUTPUT CODE 49,152 65,536 Figure 13. DNL Error with fIN = 9.7 MHz 100 6 90 SFDR (dBc) 4 80 70 SNR (dBFS) INL ERROR (LSB) SNR/SFDR (dBFS/dBc) 16,384 08678-038 10 60 50 40 30 20 2 0 –2 –4 20 30 40 50 60 SAMPLE RATE (MSPS) 70 80 –6 08678-055 0 10 0 Figure 11. AD9266-80 SNR/SFDR vs. Sample Rate with AIN = 9.7 MHz 16,384 32,768 OUTPUT CODE 49,152 65,536 08678-037 10 Figure 14. INL with fIN = 9.7 MHz 120 4.0M SFDRFS 2.8 LSB RMS 3.5M 100 NUMBER OF HITS SNR/SFDR (dBFS/dBc) 3.0M 80 SNRFS SFDR 60 SNR 40 2.5M 2.0M 1.5M 1.0M 20 500k –10 0 0 OUTPUT CODE Figure 12. AD9266-80 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz Rev. B | Page 12 of 32 Figure 15. Grounded Input Histogram 08678-048 –40 –30 –20 INPUT AMPLITUDE (dBFS) N – 12 N – 11 N – 10 N–9 N–8 N–7 N–6 N–5 N–4 N–3 N–2 N–1 N N+1 N+2 N+3 N+4 N+5 N+6 N+7 N+8 N+9 N + 10 –50 08678-061 0 –65 –60 Data Sheet AD9266 AD9266-65 AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. 120 0 65MSPS 9.7MHz @ –1dBFS SNR = 76.9dB (77.9dBFS) SFDR = 95.9dBc SFDRFS 100 –40 SNR/SFDR (dBFS/dBc) –60 –80 –100 SNRFS SFDR 60 SNR 40 20 –120 0 5 10 15 20 25 30 FREQUENCY (MHz) 0 –65 –60 08678-030 –140 –50 –40 –30 –20 INPUT AMPLITUDE (dBFS) –10 0 Figure 19. AD9266-65 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz Figure 16. AD9266-65 Single-Tone FFT with fIN = 9.7 MHz 100 0 65MSPS 69MHz @ –1dBFS SNR = 75.5dB (76.5dBFS) SFDR = 87.4dBc –20 SFDR (dBc) 90 80 SNR/SFDR (dBFS/dBc) –40 AMPLITUDE (dBFS) 80 08678-060 AMPLITUDE (dBFS) –20 –60 –80 –100 70 SNR (dBFS) 60 50 40 30 20 –120 5 10 15 20 25 30 FREQUENCY (MHz) 0 65MSPS 30.6MHz @ –1dBFS SNR = 76.6dB (77.6dBFS) SFDR = 89.9dBc –60 –80 –100 –120 0 5 10 15 20 25 30 FREQUENCY (MHz) 08678-031 AMPLITUDE (dBFS) –40 –140 0 50 100 150 INPUT FREQUENCY (MHz) 200 Figure 20. AD9266-65 SNR/SFDR vs. Input Frequency (AIN) with 2 V p-p Full Scale Figure 17. AD9266-65 Single-Tone FFT with fIN = 69 MHz –20 0 Figure 18. AD9266-65 Single-Tone FFT with fIN = 30.6 MHz Rev. B | Page 13 of 32 08678-056 0 08678-032 10 –140 AD9266 Data Sheet AD9266-40 AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. 120 0 40MSPS 9.7MHz @ –1dBFS SNR = 76.9dB (77.9dBFS) SFDR = 95.1dBc SFDRFS 100 –40 SNR/SFDR (dBFS/dBc) –60 –80 –100 SNRFS SFDR 60 SNR 40 20 –120 0 2 4 6 8 10 12 14 16 18 20 FREQUENCY (MHz) 0 –65 –60 08678-028 –140 0 40MSPS 30.6MHz @ –1dBFS SNR = 76.6dB (77.6dBFS) SFDR = 88.8dBc –20 –40 –60 –80 –100 –140 2 4 6 8 10 12 14 16 18 FREQUENCY (MHz) 20 08678-029 –120 0 –50 –40 –30 –20 INPUT AMPLITUDE (dBFS) –10 0 Figure 23. AD9266-40 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz Figure 21. AD9266-40 Single-Tone FFT with fIN = 9.7 MHz AMPLITUDE (dBFS) 80 08678-059 AMPLITUDE (dBFS) –20 Figure 22. AD9266-40 Single-Tone FFT with fIN = 30.6 MHz Rev. B | Page 14 of 32 Data Sheet AD9266 AD9266-20 AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty cycle clock, DCS disabled, unless otherwise noted. 0 120 20MSPS 9.7MHz @ –1dBFS SNR = 76.9dB (77.9dBFS) SFDR = 95.6dBc SFDRFS 100 –40 SNR/SFDR (dBFS/dBc) –60 –80 –100 60 SFDR (dBc) 40 SNR (dBc) 20 –120 0 1 2 3 4 5 6 7 8 9 10 FREQUENCY (MHz) 0 –90 08678-024 –140 Figure 24. AD9266-20 Single-Tone FFT with fIN = 9.7 MHz 20MSPS 30.6MHz @ –1dBFS SNR = 76.7dB (77.7dBFS) SFDR = 90.7dBc –20 –40 –60 –80 –100 –140 1 2 3 4 5 6 7 8 9 FREQUENCY (MHz) 10 08678-026 –120 0 –80 –70 –60 –50 –40 –30 –20 INPUT AMPLITUDE (dBFS) –10 0 Figure 26. AD9266-20 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz 0 AMPLITUDE (dBFS) SNRFS 80 08678-058 AMPLITUDE (dBFS) –20 Figure 25. AD9266-20 Single-Tone FFT with fIN = 30.6 MHz Rev. B | Page 15 of 32 AD9266 Data Sheet EQUIVALENT CIRCUITS DRVDD AVDD VIN± 08678-042 08678-039 D1_D0 TO D15_D14, OR Figure 27. Equivalent Analog Input Circuit Figure 31. Equivalent D1_D0 to D15_D14 and OR Digital Output Circuit DRVDD AVDD SCLK/DFS, MODE, SDIO/PDWN VREF 30kΩ 08678-047 7.5kΩ 350Ω 08678-043 375Ω Figure 32. Equivalent SCLK/DFS, MODE, and SDIO/PDWN Input Circuit Figure 28. Equivalent VREF Circuit AVDD DRVDD AVDD 375Ω CSB 30kΩ 350Ω 08678-045 08678-046 SENSE Figure 29. Equivalent SENSE Circuit Figure 33. Equivalent CSB Input Circuit AVDD 5Ω CLK+ AVDD 15kΩ 0.9V AVDD RBIAS AND VCM 375Ω 08678-044 08678-040 CLK– 15kΩ 5Ω Figure 30. Equivalent Clock Input Circuit Figure 34. Equivalent RBIAS and VCM Circuit Rev. B | Page 16 of 32 Data Sheet AD9266 THEORY OF OPERATION Each stage of the pipeline, excluding the last, consists of a low resolution flash ADC connected to a switched-capacitor DAC and an interstage residue amplifier (for example, a multiplying digital-to-analog converter (MDAC)). The residue amplifier 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. high IF frequencies. Either a shunt capacitor or two single-ended capacitors can be placed on the inputs to provide a matching passive network. This ultimately creates a low-pass filter at the input to limit unwanted broadband noise. See the AN-742 Application Note, the AN-827 Application Note, and the Analog Dialogue article “Transformer-Coupled Front-End for Wideband A/D Converters” (Volume 39, April 2005) for more information. In general, the precise values depend on the application. Input Common Mode The analog inputs of the AD9266 are not internally dc-biased. Therefore, in ac-coupled applications, the user must provide a dc bias externally. Setting the device so that VCM = AVDD/2 is recommended for optimum performance, but the device can function over a wider range with reasonable performance, as shown in Figure 36. 100 The output staging block aligns the data, corrects errors, and passes the data to the CMOS output buffers. The output buffers are powered from a separate (DRVDD) supply, allowing adjustment of the output voltage swing. During power-down, the output buffers go into a high impedance state. 95 SFDR (dBc) SNR/SFDR (dBFS/dBc) 90 ANALOG INPUT CONSIDERATIONS The analog input to the AD9266 is a differential switchedcapacitor circuit designed for processing differential input signals. This circuit can support a wide common-mode range while maintaining excellent performance. By using an input common-mode voltage of midsupply, users can minimize signal-dependent errors and achieve optimum performance. 85 80 SNR (dBFS) 75 70 65 60 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 INPUT COMMON-MODE VOLTAGE (V) Figure 36. SNR/SFDR vs. Input Common-Mode Voltage, fIN = 32.5 MHz, fS = 80 MSPS H An on-board, common-mode voltage reference is included in the design and is available from the VCM pin. The VCM pin must be decoupled to ground by a 0.1 μF capacitor, as described in the Applications Information section. H CSAMPLE S S S S CSAMPLE Differential Input Configurations H H Optimum performance is achieved while driving the AD9266 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. 08678-006 CPAR Figure 35. Switched-Capacitor Input Circuit The clock signal alternately switches the input circuit between sample-and-hold mode (see Figure 35). When the input circuit is switched to sample mode, the signal source must be capable of charging the sample capacitors and settling within one-half of a clock cycle. A small resistor in series with each input can help reduce the peak transient current injected from the output stage of the driving source. In addition, low Q inductors or ferrite beads can be placed on each leg of the input to reduce high differential capacitance at the analog inputs and, therefore, achieve the maximum bandwidth of the ADC. Such use of low Q inductors or ferrite beads is required when driving the converter front end at The output common-mode voltage of the ADA4938-2 is easily set with the VCM pin of the AD9266 (see Figure 37), and the driver can be configured in a Sallen-Key filter topology to provide band limiting of the input signal. 200Ω VIN 76.8Ω 33Ω ADA4938-2 0.1µF VIN– 90Ω 120Ω 10pF 33Ω AVDD ADC VIN+ VCM 200Ω Figure 37. Differential Input Configuration Using the ADA4938-2 Rev. B | Page 17 of 32 08678-007 CPAR VIN+ VIN– 08678-049 The AD9266 architecture consists of a multistage, pipelined ADC. Each stage provides sufficient overlap to correct for flash errors in the preceding stage. The quantized outputs from each stage are combined into a final 16-bit result in the digital correction logic. The pipelined architecture permits the first stage to operate with a new input sample, whereas the remaining stages operate with preceding samples. Sampling occurs on the rising edge of the clock. AD9266 Data Sheet In any configuration, the value of Shunt Capacitor C is dependent on the input frequency and source impedance and may need to be reduced or removed. Table 9 displays the suggested values to set the RC network. However, these values are dependent on the input signal and should be used only as a starting guide. For baseband applications less than approximately 10 MHz where SNR is a key parameter, differential transformer coupling is the recommended input configuration. An example is shown in Figure 38. To bias the analog input, the VCM voltage can be connected to the center tap of the secondary winding of the transformer. R VCM 08678-008 VIN– 0.1µF C Differential (pF) 22 Open Single-Ended Input Configuration Figure 38. Differential Transformer-Coupled Configuration A single-ended input can provide adequate performance in cost-sensitive applications. In this configuration, SFDR and distortion performance degrade due to the large input commonmode swing. If the source impedances on each input are matched, there should be little effect on SNR performance. Figure 39 shows a typical single-ended input configuration. 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. 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 AD9266. For applications greater than approximately 10 MHz where SNR is a key parameter, differential double balun coupling is the recommended input configuration (see Figure 40). 10µF AVDD 1kΩ 1V p-p 49.9Ω 0.1µF R 0.1µF ADC C 1kΩ 10µF VIN+ 1kΩ AVDD An alternative to using a transformer-coupled input at frequencies in the second Nyquist zone is to use the AD8352 differential driver. An example is shown in Figure 41. See the AD8352 data sheet for more information. R VIN– 1kΩ Figure 39. Single-Ended Input Configuration 0.1µF 0.1µF R Series (Ω Each) 33 125 Frequency Range (MHz) 0 to 70 70 to 200 ADC C R VIN+ 2V p-p 25Ω PA S S P 0.1µF 25Ω ADC C 0.1µF R VCM VIN– Figure 40. Differential Double Balun Input Configuration VCC ANALOG INPUT 0Ω 16 1 8, 13 11 0.1µF 2 CD RD RG 3 ANALOG INPUT 0.1µF 0Ω R VIN+ 200Ω 10 ADC C AD8352 4 5 0.1µF 0.1µF 200Ω R 14 0.1µF 0.1µF Figure 41. Differential Input Configuration Using the AD8352 Rev. B | Page 18 of 32 VIN– VCM 08678-011 0.1µF 08678-009 49.9Ω 08678-010 2V p-p Table 9. Example RC Network VIN+ R Data Sheet AD9266 0 Internal Reference Connection A comparator within the AD9266 detects the potential at the SENSE pin and configures the reference into two possible modes, which are summarized in Table 10. If SENSE is grounded, the reference amplifier switch is connected to the internal resistor divider (see Figure 42), setting VREF to 1.0 V. –0.5 –1.0 INTERNAL VREF = 0.995V –1.5 –2.0 –2.5 –3.0 0 0.6 0.8 1.0 1.2 1.4 1.6 2.0 1.8 Figure 43. VREF Accuracy vs. Load Current External Reference Operation VIN– The use of an external reference may be necessary to enhance the gain accuracy of the ADC or improve thermal drift characteristics. Figure 44 shows the typical drift characteristics of the internal reference in 1.0 V mode. ADC CORE VREF 4 SELECT LOGIC 3 2 SENSE 08678-012 ADC VREF ERROR (mV) 0.5V Figure 42. Internal Reference Configuration If the internal reference of the AD9266 is used to drive multiple converters to improve gain matching, the loading of the reference by the other converters must be considered. Figure 43 shows how the internal reference voltage is affected by loading. VREF ERROR (mV) 1 0 –1 –2 –3 –4 –5 –6 –40 –20 0 20 40 TEMPERATURE (°C) 60 80 08678-052 0.1µF 0.4 LOAD CURRENT (mA) VIN+ 1.0µF 0.2 08678-014 A stable and accurate 1.0 V voltage reference is built into the AD9266. The VREF can be configured using either the internal 1.0 V reference or an externally applied 1.0 V reference voltage. The various reference modes are summarized in the sections that follow. The Reference Decoupling section describes the best practices for PCB layout of VREF. REFERENCE VOLTAGE ERROR (%) VOLTAGE REFERENCE Figure 44. Typical VREF Drift When the SENSE pin is tied to AVDD, the internal reference is disabled, allowing the use of an external reference. An internal reference buffer loads the external reference with an equivalent 7.5 kΩ load (see Figure 28). The internal buffer generates the positive and negative full-scale references for the ADC core. Therefore, the external reference must be limited to a maximum of 1.0 V. Table 10. Reference Configuration Summary Selected Mode Fixed Internal Reference Fixed External Reference SENSE Voltage (V) AGND to 0.2 AVDD Resulting VREF (V) 1.0 internal 1.0 applied to external VREF pin Rev. B | Page 19 of 32 Resulting Differential Span (V p-p) 2.0 2.0 AD9266 Data Sheet CLOCK INPUT CONSIDERATIONS For optimum performance, clock the AD9266 sample clock inputs, CLK+ and CLK−, with a differential signal. The signal is typically ac-coupled into the CLK+ and CLK− pins via a transformer or capacitors. These pins are biased internally (see Figure 45) and require no external bias. AVDD CLK– 2pF 08678-016 2pF This limit helps prevent the large voltage swings of the clock from feeding through to other portions of the AD9266 while preserving the fast rise and fall times of the signal that are critical to a low jitter performance. 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 48. The AD9510/AD9511/AD9512/ AD9513/AD9514/AD9515/AD9516-0/AD9516-1/AD9516-2/ AD9516-3/AD9516-4/AD9516-5/AD9517-0/AD9517-1/ AD9517-2/AD9517-3/AD9517-4 clock drivers offer excellent jitter performance. 0.9V CLK+ The back-to-back Schottky diodes across the transformer/ balun secondary limit clock excursions into the AD9266 to approximately 0.8 V p-p differential. Figure 45. Equivalent Clock Input Circuit 0.1µF The AD9266 has a very flexible clock input structure. The 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 great concern, as described in the Jitter Considerations section. Figure 46 and Figure 47 show two preferred methods for clocking the AD9266 (at clock rates up to 625 MHz when using the internal clock divider). A low jitter clock source is converted from a single-ended signal to a differential signal using either an RF transformer or an RF balun. Mini-Circuits® ADT1-1WT, 1:1 Z XFMR 0.1µF CLOCK INPUT 100Ω ADC 0.1µF CLK– 50kΩ 50kΩ 240Ω 240Ω Figure 48. Differential PECL Sample Clock (Up to 625 MHz) A third option is to ac couple a differential LVDS signal to the sample clock input pins, as shown in Figure 49. The AD9510/ AD9511/AD9512/AD9513/AD9514/AD9515/AD9516-0/ AD9516-1/AD9516-2/AD9516-3/AD9516-4/AD9516-5/ AD9517-0/AD9517-1/AD9517-2/AD9517-3/AD9517-4 clock drivers offer excellent jitter performance. 0.1µF CLK+ 100Ω 50Ω CLK+ AD951x PECL DRIVER ADC 0.1µF 0.1µF 08678-017 SCHOTTKY DIODES: HSMS2822 0.1µF 0.1µF CLOCK INPUT CLK– Figure 46. Transformer-Coupled Differential Clock (Up to 200 MHz) CLK+ 0.1µF CLOCK INPUT AD951x LVDS DRIVER 100Ω ADC 0.1µF CLK– 50kΩ 08678-020 0.1µF CLOCK INPUT 0.1µF CLOCK INPUT 08678-019 Clock Input Options 50kΩ Figure 49. Differential LVDS Sample Clock (Up to 625 MHz) CLK+ 50Ω ADC 0.1µF 1nF CLK– SCHOTTKY DIODES: HSMS2822 08678-018 CLOCK INPUT 0.1µF In some applications, it may be acceptable to drive the sample clock inputs with a single-ended 1.8 V CMOS signal. In such applications, drive the CLK+ pin directly from a CMOS gate, and bypass the CLK− pin to ground with a 0.1 μF capacitor (see Figure 50). Figure 47. Balun-Coupled Differential Clock (Up to 625 MHz) VCC The RF balun configuration is recommended for clock frequencies between 125 MHz and 625 MHz, and the RF transformer is recommended for clock frequencies from 10 MHz to 200 MHz. 0.1µF CLOCK INPUT 50Ω1 1kΩ AD951x CMOS DRIVER OPTIONAL 0.1µF 100Ω 1kΩ CLK+ ADC CLK– 0.1µF 150Ω RESISTOR IS OPTIONAL. Figure 50. Single-Ended 1.8 V CMOS Input Clock (Up to 200 MHz) Rev. B | Page 20 of 32 08678-021 1nF Data Sheet AD9266 Input Clock Divider Jitter Considerations The AD9266 contains an input clock divider with the ability to divide the input clock by integer values between 1 and 8. Optimum performance can be obtained by enabling the internal duty cycle stabilizer (DCS) when using divide ratios other than 1, 2, or 4. High speed, high resolution ADCs are sensitive to the quality of the clock input. The degradation in SNR from the low frequency SNR (SNRLF) at a given input frequency (fINPUT) due to jitter (tJRMS) can be calculated by Clock Duty Cycle SNRHF = −10 log[(2π × fINPUT × tJRMS)2 + 10 ( − SNRLF /10) ] In the previous equation, the rms aperture jitter represents the clock input jitter specification. IF undersampling applications are particularly sensitive to jitter, as illustrated in Figure 52. 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. Commonly, a ±5% tolerance is required on the clock duty cycle to maintain dynamic performance characteristics. 80 75 The AD9266 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 AD9266. Noise and distortion performance are nearly flat for a wide range of duty cycles with the DCS on, as shown in Figure 51. 0.05ps 70 0.5ps 60 55 80 1.0ps 1.5ps 50 DCS OFF DCS ON 79 3.0ps 45 1 78 SNR (dBFS) 100 FREQUENCY (MHz) 77 1k Figure 52. SNR vs. Input Frequency and Jitter 76 75 74 73 72 35 40 45 50 55 POSITIVE DUTY CYCLE (%) 60 65 70 08678-064 71 70 30 10 2.0ps 2.5ps 08678-022 SNR (dBFS) 0.2ps 65 Figure 51. SNR vs. DCS On/Off Jitter in the rising edge of the input is still of concern and is not easily reduced by the internal stabilization circuit. The duty cycle control loop does not function for clock rates less than 20 MHz nominally. 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. Treat the clock input as an analog signal when aperture jitter may affect the dynamic range of the AD9266. To avoid modulating the clock signal with digital noise, keep power supplies for clock drivers separate from the ADC output driver supplies. 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. For more information, see the AN-501 Application Note and the AN-756 Application Note. Rev. B | Page 21 of 32 AD9266 Data Sheet POWER DISSIPATION AND STANDBY MODE As shown in Figure 53, the analog core power dissipated by the AD9266 is proportional to its sample rate. The digital power dissipation of the CMOS outputs are determined primarily by the strength of the digital drivers and the load on each output bit. The maximum DRVDD current (IDRVDD) can be calculated as IDRVDD = VDRVDD × CLOAD × fCLK × N where N is the number of output bits (nine, in the case of the AD9266). This maximum current occurs when every output bit switches on every clock cycle, that is, a full-scale square wave at the Nyquist frequency of fCLK/2. In practice, the DRVDD current is established by the average number of output bits switching, which is determined by the sample rate and the characteristics of the analog input signal. Reducing the capacitive load presented to the output drivers can minimize digital power consumption. The data in Figure 53 was taken using the same operating conditions as those used for the Typical Performance Characteristics, with a 5 pF load on each output driver. AD9266-80 85 65 AD9266-20 45 20 30 40 50 The AD9266 output drivers can be configured to interface with 1.8 V to 3.3 V CMOS logic families. Output data can also be multiplexed onto a single output bus to reduce the total number of traces required. The CMOS output drivers are sized to provide sufficient output current to drive a wide variety of logic families. However, large drive currents tend to cause current glitches on the supplies and may affect converter performance. Applications requiring the ADC to drive large capacitive loads or large fanouts may require external buffers or latches. Table 11. SCLK/DFS and SDIO/PDWN Mode Selection (External Pin Mode) AD9266-40 10 DIGITAL OUTPUTS As detailed in the AN-877 Application Note, Interfacing to High Speed ADCs via SPI, the data format can be selected for offset binary, twos complement, or gray code when using the SPI control. AD9266-65 95 60 70 CLOCK RATE (MSPS) 80 08678-067 ANALOG CORE POWER (mW) 105 55 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 when faster wake-up times are required. See the Memory Map section for more details. The output data format can be selected to be either offset binary or twos complement by setting the SCLK/DFS pin when operating in the external pin mode (see Table 11). 115 75 down mode and then must be recharged when returning to normal operation. As a result, wake-up time is related to the time spent in power-down mode, and shorter power-down cycles result in proportionally shorter wake-up times. Voltage at Pin AGND SCLK/DFS Offset binary (default) DRVDD Twos complement SDIO/PDWN Normal operation (default) Outputs disabled Digital Output Enable Function (OEB) Figure 53. Analog Core Power vs. Clock Rate In SPI mode, the AD9266 can be placed in power-down mode directly via the SPI port, or by using the programmable external MODE pin. In non-SPI mode, power-down is achieved by asserting the PDWN pin high. In this state, the ADC typically dissipates 500 µW. During power-down, the output drivers are placed in a high impedance state. Asserting PDWN low (or the MODE pin in SPI mode) returns the AD9266 to its normal operating mode. Note that PDWN is referenced to the digital output driver supply (DRVDD) and should not exceed that supply voltage. Low power dissipation in power-down mode is achieved by shutting down the reference, reference buffer, biasing networks, and clock. Internal capacitors are discharged when entering power- When using the SPI interface, the data outputs and DCO can be independently three-stated by using the programmable external MODE pin. The MODE pin (OEB) function is enabled via Bits[6:5] of Register 0x08. If the MODE pin is configured to operate in traditional OEB mode and the MODE pin is low, the output data drivers and DCOs are enabled. If the MODE pin is high, the output data drivers and DCOs are placed in a high impedance state. This OEB function is not intended for rapid access to the data bus. Note that the MODE pin is referenced to the digital output driver supply (DRVDD) and should not exceed that supply voltage. Rev. B | Page 22 of 32 Data Sheet AD9266 TIMING The AD9266 provides latched data with a pipeline delay of eight clock cycles. Data outputs are available one propagation delay (tPD) after the rising edge of the clock signal. Minimize the length of the output data lines and loads placed on them to reduce transients within the AD9266. These transients can degrade converter dynamic performance. The lowest typical conversion rate of the AD9266 is 3 MSPS. At clock rates below 3 MSPS, dynamic performance may degrade. Data Clock Output (DCO) The AD9266 provides a DCO signal that is intended for capturing the data in an external register. The CMOS data outputs are valid on the rising and falling edge of DCO. See Figure 2 for a graphical timing description. Table 12. Output Data Format Input (V) VIN+ − VIN− VIN+ − VIN− VIN+ − VIN− VIN+ − VIN− VIN+ − VIN− Condition (V) < −VREF − 0.5 LSB = −VREF =0 = +VREF − 1.0 LSB > +VREF − 0.5 LSB Offset Binary Output Mode 0000 0000 0000 0000 0000 0000 0000 0000 1000 0000 0000 0000 1111 1111 1111 1111 1111 1111 1111 1111 Rev. B | Page 23 of 32 Twos Complement Mode 1000 0000 0000 0000 1000 0000 0000 0000 0000 0000 0000 0000 0111 1111 1111 1111 0111 1111 1111 1111 OR 1 0 0 0 1 AD9266 Data Sheet OUTPUT TEST The AD9266 includes various output test options to place predictable values on the outputs of the AD9266. OUTPUT TEST MODES The output test options are described in Table 16 at Address 0x0D. When an output test mode is enabled, the analog section of the ADC is disconnected from the digital back end blocks and the test pattern is run through the output formatting block. Some of the test patterns are subject to output formatting, and some are not. The PN generators from the PN sequence tests can be reset by setting Bit 4 or Bit 5 of Register 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. Rev. B | Page 24 of 32 Data Sheet AD9266 SERIAL PORT INTERFACE (SPI) The AD9266 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 more detailed operational information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. The falling edge of CSB, in conjunction with the rising edge of SCLK, determines the start of the framing. An example of the serial timing and its definitions can be found in Figure 54 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, as shown in Figure 54. Other modes involving the CSB pin are available. CSB can be held low indefinitely, which permanently enables the device; this is called streaming. 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. This mode turns on any SPI pin secondary functions. Three pins define the SPI of this ADC: SCLK, SDIO, and CSB (see Table 13). The SCLK (a serial clock) is used to synchronize the read and write data presented from and to the ADC. SDIO (serial data input/output) is a dual-purpose pin that allows data to be sent and read from the internal ADC memory map registers. The CSB (chip select bar) is an active-low control that enables or disables the read and write cycles. All data is composed of 8-bit words. 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. This allows the serial data input/output (SDIO) pin to change direction from an input to an output at the appropriate point in the serial frame. In addition to word length, the instruction phase determines whether the serial frame is a read or write operation, allowing the serial port to be used both to program the chip and to read the contents of the on-chip memory. If the instruction is a readback operation, performing a readback causes the serial data input/ output (SDIO) pin to change direction from an input to an output at the appropriate point in the serial frame. Table 13. Serial Port Interface Pins Pin SCLK SDIO CSB Function Serial clock. The serial shift clock input, which 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 Data can be sent in MSB-first mode or in LSB-first mode. MSB first is the default on power-up and can be changed via the SPI port configuration register. For more information about this and other features, see the 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 54. Serial Port Interface Timing Diagram Rev. B | Page 25 of 32 D4 D3 D2 D1 D0 DON’T CARE 08678-023 SCLK DON’T CARE AD9266 Data Sheet HARDWARE INTERFACE The pins described in Table 13 constitute the physical interface between the programming device of the user and the serial port of the AD9266. The SCLK pin and the CSB pin function as inputs when using the SPI interface. The SDIO pin is bidirectional, functioning as an input during write phases and as an output during readback. The SPI interface is flexible enough to be controlled by either FPGAs or microcontrollers. One method for SPI configuration is described in detail in the AN-812 Application Note, Microcontroller-Based Serial Port Interface (SPI) Boot Circuit. 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 AD9266 to prevent these signals from transitioning at the converter inputs during critical sampling periods. SDIO/PDWN and SCLK/DFS serve a dual function when the SPI interface is not being used. When the pins are strapped to DRVDD or ground during device power-on, they are associated with a specific function. The Digital Outputs section describes the strappable functions supported on the AD9266. CONFIGURATION WITHOUT THE SPI In applications that do not interface to the SPI control registers, the SDIO/PDWN pin and the SCLK/DFS pin serve as standalone CMOS-compatible control pins. When the device is powered up, it is assumed that the user intends to use the pins as static control lines for the power-down and output data format feature control. In this mode, connect the CSB chip select to DRVDD, which disables the serial port interface. Table 14. Mode Selection Pin SDIO/PDWN SCLK/DFS External Voltage DRVDD AGND (default) DRVDD AGND (default) Configuration Chip power-down mode Normal operation (default) Twos complement enabled Offset binary enabled SPI ACCESSIBLE FEATURES Table 15 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 AD9266 part-specific features are described in detail in Table 16. Table 15. Features Accessible Using the SPI Feature Modes Clock Offset Test I/O Output Mode Output Phase Output Delay Rev. B | Page 26 of 32 Description Allows the user to set either power-down mode or standby mode Allows the user to access the DCS via the SPI 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 up outputs Allows the user to set the output clock polarity Allows the user to vary the DCO delay Data Sheet AD9266 MEMORY MAP READING THE MEMORY MAP REGISTER TABLE DEFAULT VALUES Each row in the memory map register table (see Table 16) contains eight bit locations. The memory map is roughly divided into four sections: the chip configuration registers (Address 0x00 to Address 0x02); the device index and transfer register (Address 0xFF); the program registers, including setup, control, and test (Address 0x08 to Address 0x2A); and the AD9266-specific customer SPI control register (Address 0x101). After the AD9266 is reset, critical registers are loaded with default values. The default values for the registers are given in the memory map register table (see Table 16). Table 16 documents the default hexadecimal value for each hexadecimal address shown. The column with the heading Bit 7 (MSB) is the start of the default hexadecimal value given. For example, Address 0x2A, the OR/MODE select register, has a hexadecimal default value of 0x01. This means that in Address 0x2A, Bits[7:1] = 0, and Bit 0 = 1. This setting is the default OR/MODE setting. The default value results in the programmable external MODE/OR pin (Pin 23) functioning as an out-of-range digital output. 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 controlled by Register 0x00 to Register 0xFF. The remaining register, Register 0x101, is documented in the Memory Map Register Descriptions section that follows Table 16. Logic Levels 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 to Address 0x18 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 then the bit autoclears. OPEN LOCATIONS All address and bit locations that are not included in the SPI map 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 0x2A). If the entire address location is open, it is omitted from the SPI map (for example, Address 0x13) and should not be written. Rev. B | Page 27 of 32 AD9266 Data Sheet MEMORY MAP REGISTER TABLE All address and bit locations that are not included in Table 16 are not currently supported for this device. Table 16. Addr Bit 7 (Hex) Register Name (MSB) Chip Configuration Registers 0x00 0 SPI port configuration 0x01 Chip ID 0x02 Chip grade 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, Bits[7:0] AD9266 = 0x78 Open Speed grade ID, Bits[6:4] (identify device variants of chip ID) 20 MSPS = 000 40 MSPS = 001 65 MSPS = 010 80 MSPS = 011 Device Index and Transfer Register 0xFF Transfer Program Registers 0x08 Modes 0x09 Clock 0x0B Clock divide 0x0D Test mode 0x10 Offset adjust 0x14 Output mode External Pin 23 mode input enable Read only Transfer Open External Pin 23 function when high 00 = full powerdown 01 = standby 10 = normal mode: output disabled 11 = normal mode: output enabled Open Open 00 = chip run 01 = full power-down 10 = standby 11 = chip wide digital reset Duty cycle stabilize Clock divider, Bits[2:0] 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 User test mode Output test mode, Bits[3:0] (local) Reset PN Reset PN long gen short gen 00 = single 0000 = off (default) 0001 = midscale short 01 = alternate 0010 = positive FS 10 = single once 0011 = negative FS 11 = alternate once 0100 = alternating checkerboard 0101 = PN 23 sequence 0110 = PN 9 sequence 0111 = 1/0 word toggle 1000 = user input 1001 = 1/0 bit toggle 1010 = 1× sync 1011 = one bit high 1100 = mixed bit frequency 8-bit device offset adjustment, Bits[7:0] (local) Offset adjust in LSBs from +127 to −128 (twos complement format) Open Open 00 = 3.3 V CMOS Output Output 00 = offset binary disable invert 01 = twos complement 10 = 1.8 V CMOS 10 = gray code 11 = offset binary Rev. B | Page 28 of 32 0x18 Read only Open Open Default Value (Hex) Comments The nibbles are mirrored so that LSB- or MSB-first mode registers correctly, regardless of shift mode. Unique chip ID used to differentiate devices; read only. Unique speed grade ID used to differentiate devices; read only. 0x00 Synchronously transfers data from the master shift register to the slave. 0x00 Determines various generic modes of chip operation. 0x01 Enable internal duty cycle stabilizer (DCS). The divide ratio is the value plus 1. 0x00 0x00 When set, the test data is placed on the output pins in place of normal data. 0x00 Device offset trim. 0x00 Configures the outputs and the format of the data. Data Sheet AD9266 Addr (Hex) 0x15 Register Name Output adjust 0x16 Output phase DCO output polarity 0 = normal 1 = inverted 0x17 Output delay Enable DCO delay Open Enable data delay 0x19 USER_PATT1_LSB B7 B6 B5 B4 0x1A USER_PATT1_MSB B15 B14 B13 0x1B USER_PATT2_LSB B7 B6 0x1C USER_PATT2_MSB B15 B14 0x2A OR/MODE select Bit 7 (MSB) Bit 6 3.3 V DCO drive strength 00 = 1 stripe (default) 01 = 2 stripes 10 = 3 stripes 11 = 4 stripes AD9266-Specific Customer SPI Control Register USR2 0x10 1 Bit 5 Bit 4 1.8 V DCO drive strength 00 = 1 stripe 01 = 2 stripes 10 = 3 stripes (default) 11 = 4 stripes Open Bit 3 Bit 2 3.3 V data drive strength 00 = 1 stripe (default) 01 = 2 stripes 10 = 3 stripes 11 = 4 stripes Bit 0 Bit 1 (LSB) 1.8 V data drive strength 00 = 1 stripe 01 = 2 stripes 10 = 3 stripes (default) 11 = 4 stripes Default Value (Hex) 0x22 B3 Input clock phase adjust, Bits[2:0] (Value is number of input clock cycles of phase delay) 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 DCO/data delay[2:0] (typical values) 000 = 0.56 ns 001 = 1.12 ns 010 = 1.68 ns 011 = 2.24 ns 100 = 2.80 ns 101 = 3.36 ns 110 = 3.92 ns 111 = 4.48 ns B2 B1 B0 B12 B11 B10 B9 B8 0x00 B5 B4 B3 B2 B1 B0 0x00 B13 B12 B11 B10 B9 B8 0x00 0 = MODE 1 = OR (default) 0x01 Disable SDIO pulldown 0x08 Open Open Open Enable GCLK detect Rev. B | Page 29 of 32 Run GCLK Open Comments Determines CMOS output drive strength properties. 0x00 On devices that use global clock divide, determines which phase of the divider output is used to supply the output clock; internal latching is unaffected. 0x00 Sets the fine output delay of the output clock but does not change internal timing. (Typical values) 0x00 User-defined pattern, 1 LSB. User-defined pattern, 1 MSB. User-defined pattern, 2 LSB. User-defined pattern, 2 MSB. Selects I/O functionality in conjunction with Address 0x08 for MODE (input) or OR (output) on External Pin 23. Enables internal oscillator for clock rates of <5 MHz. AD9266 Data Sheet MEMORY MAP REGISTER DESCRIPTIONS Bit 2—Run GCLK For additional information about functions that are controlled in Register 0x00 to Register 0xFF, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. This bit enables the GCLK oscillator. For some applications with encode rates below 10 MSPS, it may be preferable to set this bit high to supersede the GCLK detector. USR2 (Register 0x101) Bit 3—Enable GCLK Detect Bit 0—Disable SDIO Pull-Down Normally set high, this bit enables a circuit that detects encode rates below about 5 MSPS. When a low encode rate is detected, an internal oscillator, GCLK, is enabled, ensuring the proper operation of several circuits. If set low, the detector is disabled. This bit can be set high to disable the internal 30 kΩ pull-down on the SDIO pin, which can be used to limit the loading when many devices are connected to the SPI bus. Rev. B | Page 30 of 32 Data Sheet AD9266 APPLICATIONS INFORMATION DESIGN GUIDELINES Before starting design and layout of the AD9266 as a system, it is recommended that the designer become familiar with these guidelines, which discuss the special circuit connections and layout requirements needed for certain pins. Power and Ground Recommendations When connecting power to the AD9266, it is strongly recommended that two separate supplies be used. Use one 1.8 V supply for analog (AVDD); use a separate 1.8 V to 3.3 V supply for the digital output supply (DRVDD). If a common 1.8 V AVDD and DRVDD supply must be used, the AVDD and DRVDD domains must be isolated with a ferrite bead or filter choke and separate decoupling capacitors. Several different decoupling capacitors can be used to cover both high and low frequencies. Locate 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 AD9266. With proper decoupling and smart partitioning of the PCB analog, digital, and clock sections, optimum performance is easily achieved. Exposed Paddle Thermal Heat Sink Recommendations The exposed paddle (Pin 0) is the only ground connection for the AD9266; therefore, it must be connected to analog ground (AGND) on the PCB. To achieve the best electrical and thermal performance, mate an exposed (no solder mask) continuous copper plane on the PCB to the AD9266 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. Fill or plug these vias with nonconductive epoxy. To maximize the coverage and adhesion between the ADC and the PCB, overlay a silkscreen 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). Encode Clock For optimum dynamic performance, use a low jitter encode clock source with a 50% duty cycle ± 5% to clock the AD9266. VCM The VCM pin should be decoupled to ground with a 0.1 μF capacitor, as shown in Figure 38. RBIAS The AD9266 requires that a 10 kΩ resistor be placed between the RBIAS pin and ground. This resistor sets the master current reference of the ADC core and should have at least a 1% tolerance. Reference Decoupling Externally decouple the VREF pin to ground with a low ESR, 1.0 μF capacitor in parallel with a low ESR, 0.1 μF ceramic capacitor. 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 AD9266 to keep these signals from transitioning at the converter inputs during critical sampling periods. Rev. B | Page 31 of 32 AD9266 Data Sheet OUTLINE DIMENSIONS 0.30 0.25 0.18 32 25 1 24 0.50 BSC *3.75 3.60 SQ 3.55 EXPOSED PAD 17 TOP VIEW 0.80 0.75 0.70 0.50 0.40 0.30 8 16 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.20 REF SEATING PLANE PIN 1 INDICATOR 9 BOTTOM VIEW 0.25 MIN FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. *COMPLIANT TO JEDEC STANDARDS MO-220-WHHD-5 WITH EXCEPTION TO EXPOSED PAD DIMENSION. 08-16-2010-B PIN 1 INDICATOR 5.10 5.00 SQ 4.90 Figure 55. 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 5 mm × 5 mm Body, Very Very Thin Quad (CP-32-12) Dimensions shown in millimeters ORDERING GUIDE Model 1 AD9266BCPZ-80 AD9266BCPZRL7-80 AD9266BCPZ-65 AD9266BCPZRL7-65 AD9266BCPZ-40 AD9266BCPZRL7-40 AD9266BCPZ-20 AD9266BCPZRL7-20 AD9266-80EBZ AD9266-65EBZ AD9266-40EBZ AD9266-20EBZ 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 –40°C to +85°C –40°C to +85°C Package Description 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ] Evaluation Board Evaluation Board Evaluation Board Evaluation Board Z = RoHS Compliant Part. ©2010–2016 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D08678-0-3/16(B) Rev. B | Page 32 of 32 Package Option CP-32-12 CP-32-12 CP-32-12 CP-32-12 CP-32-12 CP-32-12 CP-32-12 CP-32-12