12-Bit, 80 MSPS/105 MSPS ADC AD9432 FEATURES GENERAL INTRODUCTION On-chip reference and track-and-hold On-chip input buffer Power dissipation: 850 mW typical at 105 MSPS 500 MHz analog bandwidth SNR: 67 dB @ 49 MHz AIN at 105 MSPS SFDR: 80 dB @ 49 MHz AIN at 105 MSPS 2.0 V p-p analog input range 5.0 V supply operation 3.3 V CMOS/TTL outputs Twos complement output format The AD9432 is a 12-bit, monolithic sampling analog-to-digital converter (ADC) with an on-chip track-and-hold circuit and is optimized for high speed conversion and ease of use. The product operates up to a 105 MSPS conversion rate with outstanding dynamic performance over its full operating range. The ADC requires only a single 5.0 V power supply and a 105 MHz encode clock for full performance operation. No external reference or driver components are required for many applications. The digital outputs are TTL-/CMOS-compatible, and a separate output power supply pin supports interfacing with 3.3 V logic. The encode input supports either differential or single-ended mode and is TTL-/CMOS-compatible. APPLICATIONS Communications Base stations and zero-IF subsystems Wireless local loop (WLL) Local multipoint distribution service (LMDS) HDTV broadcast cameras and film scanners Fabricated on an advanced BiCMOS process, the AD9432 is available in a 52-lead low profile quad flat package (LQFP) and in a 52-lead thin quad flat package (TQFP_EP). The AD9432 is specified over the industrial temperature range of −40°C to +85°C. FUNCTIONAL BLOCK DIAGRAM VCC BUF T/H AIN PIPELINE ADC 12 12 OR ENCODE ENCODE D11 TO D0 OUTPUT STAGING TIMING REF AD9432 GND VREFOUT VREFIN 00587-001 AIN VDD Figure 1. Rev. F 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 ©2002–2009 Analog Devices, Inc. All rights reserved. AD9432 TABLE OF CONTENTS Features .............................................................................................. 1 Terminology .................................................................................... 11 Applications ....................................................................................... 1 Equivalent Circuits ......................................................................... 12 General Introduction ....................................................................... 1 Theory of Operation ...................................................................... 13 Functional Block Diagram .............................................................. 1 Analog Input ............................................................................... 13 Revision History ............................................................................... 2 Encode Input ............................................................................... 13 Specifications..................................................................................... 3 Encode Voltage Level Definition.............................................. 13 Timing Diagram ........................................................................... 5 Digital Outputs ........................................................................... 14 Absolute Maximum Ratings............................................................ 6 Voltage Reference ....................................................................... 14 Explanation of Test Levels ........................................................... 6 Timing ......................................................................................... 14 Thermal Characteristics .............................................................. 6 Applications Information .............................................................. 15 ESD Caution .................................................................................. 6 Using the AD8138 to Drive the AD9432 ................................ 15 Pin Configurations and Function Descriptions ........................... 7 Outline Dimensions ....................................................................... 16 Typical Performance Characteristics ............................................. 8 Ordering Guide .......................................................................... 16 REVISION HISTORY 6/09—Rev. E to Rev. F 1/02—Rev. D to Rev. E Updated Format .................................................................. Universal Reorganized Layout ............................................................ Universal Added TQFP_EP Package ................................................. Universal Deleted LQFP_ED Package ............................................... Universal Changes to Thermal Characteristics Section ................................ 6 Changes to Pin Configurations and Function Descriptions Section ................................................................................................ 7 Changes to Terminology Section.................................................. 11 Deleted Evaluation Board Section ................................................ 15 Updated Outline Dimensions ....................................................... 16 Changes to Ordering Guide .......................................................... 16 Edits to Specifications .......................................................................3 Edits to Absolute Maximum Ratings ..............................................4 Edits to Ordering Guide ...................................................................4 Addition of Text to Using the AD9432 Section .......................... 10 Edits to Figure 17a .......................................................................... 15 Edits to Figure 17b ......................................................................... 16 Addition of SQ-52 Package Outline............................................. 18 Rev. F | Page 2 of 16 AD9432 SPECIFICATIONS VDD = 3.3 V, VCC = 5.0 V; external reference; differential encode input, unless otherwise noted. Table 1. Parameter RESOLUTION DC ACCURACY Differential Nonlinearity (DNL) Integral Nonlinearity (INL) No Missing Codes Gain Error 1 Gain Tempco1 ANALOG INPUTS (AIN, AIN) Input Voltage Range Common-Mode Voltage Input Offset Voltage Input Resistance Input Capacitance Analog Bandwidth, Full Power ANALOG REFERENCE Output Voltage Tempco Input Bias Current SWITCHING PERFORMANCE Maximum Conversion Rate Minimum Conversion Rate Encode Pulse Width High (tEH) Encode Pulse Width Low (tEL) Aperture Delay (tA) Aperture Uncertainty (Jitter) Output Valid Time (tV) 2 Output Propagation Delay (tPD)2 Output Rise Time (tR)2 Output Fall Time (tF)2 Out-of-Range Recovery Time Transient Response Time Latency DIGITAL INPUTS Encode Input Common Mode Differential Input (ENCODE, ENCODE) Single-Ended Input Logic 1 Voltage Logic 0 Voltage Input Resistance Input Capacitance DIGITAL OUTPUTS Logic 1 Voltage (VDD = 3.3 V) Logic 0 Voltage (VDD = 3.3 V) Output Coding Temp Test Level 80 MSPS Typ 12 25°C Full 25°C Full Full 25°C Full I VI I VI VI I V Full Full Full Full 25°C 25°C V V VI VI V V Full Full Full VI V VI 2.4 Full Full 25°C 25°C 25°C 25°C Full Full Full Full 25°C 25°C Full VI IV IV IV V V VI VI V V V V IV 80 Full Full V V Full Full Full 25°C IV IV VI V 2.0 Full Full VI VI VDD − 0.05 Min −0.75 −1.0 −1.0 −1.5 ±0.25 ±0.5 ±0.5 ±1.0 Guaranteed +2 150 −5 2 3.0 ±0 3 4 500 −5 2 2.5 50 15 Max Min +0.75 +1.0 +1.0 +1.5 −0.75 −1.0 −1.0 −1.5 +7 −5 +5 4 −5 2 2.6 2.4 105 MSPS Typ Max 12 ±0.25 ±0.5 ±0.5 ±1.0 Guaranteed +2 150 2 3.0 ±0 3 4 500 2.5 50 15 50 +0.75 +1.0 +1.0 +1.5 LSB LSB LSB LSB +7 % FS ppm/°C +5 4 2.6 50 105 1 4.0 4.0 6.2 6.2 2.0 0.25 5.3 5.5 2.1 1.9 2 2 10 3.0 1 4.0 4.0 4.8 4.8 2.0 0.25 5.3 5.5 2.1 1.9 2 2 10 3.0 8.0 1.6 750 8.0 1.6 750 3 5 4.5 0.05 Twos complement Rev. F | Page 3 of 16 3 5 4.5 V p-p V mV kΩ pF MHz V ppm/°C μΑ MSPS MSPS ns ns ns ps rms ns ns ns ns ns ns Cycles V mV 2.0 0.8 8 Unit Bits 0.8 8 VDD − 0.05 0.05 Twos complement V V kΩ pF V V AD9432 Parameter POWER SUPPLY Power Dissipation 3 IVCC IVDD Power Supply Rejection Ratio (PSRR) DYNAMIC PERFORMANCE 4 Signal-to-Noise Ratio (SNR) (Without Harmonics) fIN = 10 MHz fIN = 40 MHz fIN = 49 MHz fIN = 70 MHz Signal-to-Noise and Distortion (SINAD) Ratio (with Harmonics) fIN = 10 MHz fIN = 40 MHz fIN = 49 MHz fIN = 70 MHz Effective Number of Bits (ENOB) fIN = 10 MHz fIN = 40 MHz fIN = 49 MHz fIN = 70 MHz Second-Order and Third-Order Harmonic Distortion fIN = 10 MHz fIN = 40 MHz fIN = 49 MHz fIN = 70 MHz Worst Other Harmonic or Spur (Excluding Second-Order and Third-Order Harmonics) fIN = 10 MHz fIN = 40 MHz fIN = 49 MHz fIN = 70 MHz Two-Tone Intermodulation Distortion (IMD) fIN1 = 29.3 MHz; fIN2 = 30.3 MHz fIN1 = 70.3 MHz; fIN2 = 71.3 MHz Temp Test Level Min 80 MSPS Typ Max Full Full Full 25°C VI VI VI I −5 790 158 9.5 +0.5 1000 200 12.2 +5 25°C 25°C 25°C 25°C I I I V 65.5 65 25°C 25°C 25°C 25°C I I I V 65 64.5 25°C 25°C 25°C 25°C V V V V 25°C 25°C 25°C 25°C I I I V −75 −73 25°C 25°C 25°C 25°C I I I V −80 −80 25°C 25°C V V 67.5 67.2 67.0 66.1 67.2 66.9 66.7 65.8 Min 105 MSPS Typ Max Unit −5 850 170 12.5 +0.5 mW mA mA mV/V 65.5 64 65 63 11.0 10.9 10.9 10.7 −85 −85 −83 −80 −90 −90 −90 −90 −75 −66 1 −75 −72 −80 −80 1100 220 16 +5 67.5 67.2 67.0 66.1 dB dB dB dB 67.2 66.9 66.7 65.8 dB dB dB dB 11.0 10.9 10.9 10.7 Bits Bits Bits Bits −85 −83 −80 −78 dBc dBc dBc dBc −90 −90 −90 −90 dBc dBc dBc dBc −75 −66 dBc dBc Gain error and gain temperature coefficients are based on the ADC only (with a fixed 2.5 V external reference and a 2 V p-p differential analog input). tV and tPD are measured from the transition points of the ENCODE input to the 50%/50% levels of the digital output swing. The digital output load during testing is not to exceed an ac load of 10 pF or a dc current of ±40 μA. Rise and fall times are measured from 10% to 90%. 3 Power dissipation measured with encode at rated speed and a dc analog input (outputs static, IVDD = 0). 4 SNR/harmonics based on an analog input voltage of –0.5 dBFS referenced to a 2 V full-scale input range. 2 Rev. F | Page 4 of 16 AD9432 TIMING DIAGRAM SAMPLE N – 1 SAMPLE N SAMPLE N + 10 SAMPLE N + 11 AIN tA SAMPLE N + 1 tEH tEL SAMPLE N + 9 1/fS ENCODE ENCODE D11 TO D0 DATA N – 11 DATA N – 10 DATA N–9 DATA N–2 DATA N – 1 Figure 2. Timing Diagram Rev. F | Page 5 of 16 tV DATA N DATA N + 1 00587-003 tPD AD9432 ABSOLUTE MAXIMUM RATINGS THERMAL CHARACTERISTICS Table 2. Parameter VDD VCC Analog Inputs Digital Inputs VREFIN Digital Output Current Operating Temperature Range Storage Temperature Range Maximum Junction Temperature Maximum Case Temperature Table 3 lists AD9432 thermal characteristics for simulated typical performance in a 4-layer JEDEC board, horizontal orientation. Rating 6V 6V −0.5 V to VCC + 0.5 V −0.5 V to VDD + 0.5 V −0.5 V to VCC + 0.5 V 20 mA −55°C to +125°C −65°C to +150°C 150°C 150°C Table 3. Thermal Resistance Package Type 52-Lead LQFP (ST-52) No Airflow 52-Lead TQFP_EP (SV-52-2)1 No Airflow 1.0 m/s Airflow 1 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. θJA EXPLANATION OF TEST LEVELS I II 100% production tested. 100% production tested at 25°C and sample tested at specified temperatures. III Sample tested only. IV Parameter is guaranteed by design and characterization testing. V Parameter is a typical value only. VI 100% production tested at 25°C; guaranteed by design and characterization testing for industrial temperature range. Rev. F | Page 6 of 16 θJC 50 2 19.3 Bottom of package (soldered exposed pad). ESD CAUTION θJMA 16 Unit °C/W °C/W °C/W °C/W AD9432 VCC 2 PIN 1 GND DNC VCC GND VCC VREFIN VREFOUT VCC GND AIN GND 1 39 GND VCC 2 38 GND GND 3 39 GND PIN 1 38 GND 37 VCC GND 3 37 VCC GND 4 GND 4 36 VCC VCC 5 AD9432 VCC 5 VCC 6 VCC 6 TOP VIEW (Not to Scale) ENCODE 7 ENCODE 8 32 VDD GND 9 31 DGND AD9432 35 GND TOP VIEW (Not to Scale) 34 GND ENCODE 33 GND ENCODE 8 36 VCC 7 35 GND 34 GND 33 GND 32 VDD GND 9 31 DGND VCC 10 30 D0 (LSB) GND 11 29 D1 GND 11 29 D1 DGND 12 28 D2 DGND 12 28 D2 VDD 13 VDD 13 27 D3 30 D0 (LSB) D4 D5 DGND VDD VDD DGND D6 D7 D8 D9 D10 OR 00587-002 D4 D5 DGND VDD VDD DGND D6 D7 D8 D9 D10 OR D11 (MSB) 14 15 16 17 18 19 20 21 22 23 24 25 26 NOTES 1. DNC = DO NOT CONNECT. 27 D3 14 15 16 17 18 19 20 21 22 23 24 25 26 D11 (MSB) VCC 10 NOTES 1. ALTHOUGH NOT REQUIRED IN ALL APPLICATIONS, THE EXPOSED PADDLE ON THE UNDERSIDE OF THE PACKAGE SHOULD BE SOLDERED TO THE GROUND PLANE. SOLDERING THE EXPOSED PADDLE TO THE PCB INCREASES THE RELIABILITY OF THE SOLDER JOINTS, MAXIMIZING THE THERMAL CAPABILITY OF THE PACKAGE. Figure 3. Pin Configuration, LQFP 00587-044 GND AIN 52 51 50 49 48 47 46 45 44 43 42 41 40 52 51 50 49 48 47 46 45 44 43 42 41 40 1 GND VCC GND DNC VCC GND VCC VREFIN VREFOUT VCC GND AIN AIN GND VCC PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS Figure 4. Pin Configuration, TQFP_EP Table 4. Pin Function Descriptions Pin No. 1, 3, 4, 9, 11, 33, 34, 35, 38, 39, 40, 43, 48, 51 2, 5, 6, 10, 36, 37, 42, 44, 47, 52 7 8 12, 21, 24, 31 13, 22, 23, 32 14 15 to 20, 25 to 30 41 45 46 49 50 Mnemonic GND Description Analog Ground. VCC Analog Supply (5 V). ENCODE ENCODE DGND VDD OR D11 to D6, D5 to D0 DNC VREFIN VREFOUT AIN AIN Exposed Pad (TQFP_EP) Encode Clock for ADC, Complementary. Encode Clock for ADC, True. ADC samples on rising edge of ENCODE. Digital Output Ground. Digital Output Power Supply (2.7 V to 3.6 V). Out-of-Range Output. Digital Output. Do Not Connect. Reference Input for ADC (2.5 V Typical). Bypass with 0.1 μF capacitor to ground. Internal Reference Output (2.5 V Typical). Analog Input, True. Analog Input, Complementary. Although not required in all applications, the exposed paddle on the underside of the TQFP_EP package should be soldered to the ground plane. Soldering the exposed paddle to the PCB increases the reliability of the solder joints, maximizing the thermal capability of the package. Rev. F | Page 7 of 16 AD9432 TYPICAL PERFORMANCE CHARACTERISTICS 70 90 AIN = –0.5dBFS AIN = 10.3MHz 85 65 80 SNR (dB) SNR/SINAD/SFDR (dB) SFDR 75 70 SNR 60 55 SINAD 60 0 20 40 60 80 100 120 140 50 160 00587-012 00587-009 65 0 50 100 150 200 250 ANALOG INPUT FREQUENCY (MHz) ENCODE (MSPS) Figure 5. SNR/SINAD/SFDR vs. fS, fIN = 10.3 MHz Figure 8. SNR vs. fIN, Encode = 105 MSPS 100 –50 AIN = 10.3MHz ENCODE = 105MSPS –55 90 –60 HARMONICS (dBc) –70 –75 –80 –85 80 2ND or 3RD (–6.0dBFS) 70 60 3RD 2ND or 3RD (–0.5dBFS) –90 50 –95 00587-010 2ND –100 0 20 40 60 80 100 120 140 2ND or 3RD (–3.0dBFS) 40 0 160 20 40 60 80 100 120 140 160 180 200 ANALOG INPUT FREQUENCY (MHz) ENCODE (MSPS) Figure 6. Second-Order and Third-Order Harmonics vs. fS, fIN = 10.3 MHz Figure 9. Second-Order and Third-Order Harmonics vs. fIN, fS = 105 MSPS 100 70 ENCODE = 105MSPS ENCODE = 105MSPS WORST OTHER (–0.5dBFS) 90 WORST OTHER (dBc) 65 60 SINAD (–3.0dBFS) 55 SINAD (–6.0dBFS) 50 SINAD (–0.5dBFS) 80 WORST OTHER (–6.0dBFS) 70 WORST OTHER (–3.0dBFS) 60 40 0 20 40 60 80 100 120 140 160 180 00587-014 50 45 00587-011 SINAD (dB) 00587-013 HARMONICS (dBc) –65 40 0 200 20 40 60 80 100 120 140 160 180 200 ANALOG INPUT FREQUENCY (MHz) ANALOG INPUT FREQUENCY (MHz) Figure 7. SINAD vs. fIN, fS = 105 MSPS Figure 10. Worst Other (Excluding Second-Order and Third-Order Harmonics) vs. fIN, fS = 105 MSPS Rev. F | Page 8 of 16 AD9432 0 ENCODE = 105MSPS AIN = 10.3MHz (–0.53dBFS) SNR = 67.32dB SINAD = 67.07dB SFDR = –85dBc –20 –20 AMPLITUDE (dBFS) –30 –40 –50 –60 –70 –80 –50 –60 –70 –80 –90 –100 –100 –110 –120 –110 –120 FREQUENCY FREQUENCY Figure 11. FFT: fS = 105 MSPS, fIN = 10.3 MHz Figure 14. FFT: fS = 105 MSPS, fIN = 50.3 MHz 0 0 –20 –60 –70 –80 –40 –50 –60 –70 –80 –90 –90 –100 –100 –120 –110 –120 FREQUENCY FREQUENCY Figure 12. FFT: fS = 105 MSPS, fIN = 27 MHz Figure 15. Two-Tone FFT, Wideband: fS = 105 MSPS, AIN1 = 29.3 MHz, AIN2 = 30.3 MHz 0 –20 –10 –20 –50 –60 –70 –80 –40 –50 –60 –70 –80 –90 –90 –100 –100 –110 –120 AIN1 = 70.3MHz (–7dBFS) AIN2 = 71.3MHz (–7dBFS) ENCODE = 105MSPS –30 –40 00587-017 AMPLITUDE (dBFS) –30 0 ENCODE = 105MSPS AIN = 40.9MHz (–0.56dBFS) SNR = 67.2dB SINAD = 66.9dB SFDR = –80dBc AMPLITUDE (dBFS) –10 00587-019 –50 –110 AIN1 = 29.3MHz (–7dBFS) AIN2 = 30.3MHz (–7dBFS) ENCODE = 105MSPS –30 –40 00587-016 AMPLITUDE (dBFS) –30 –10 00587-020 –20 ENCODE = 105MSPS AIN = 27.0MHz (–0.52dBFS) SNR = 67.3dB SINAD = 67.0dB SFDR = –83.1dBc AMPLITUDE (dBFS) –10 ENCODE = 105MSPS AIN = 50.3MHz (–0.46dBFS) SNR = 67.0dB SINAD = 66.7dB SFDR = –80dBc –40 –90 00587-015 AMPLITUDE (dBFS) –30 –10 00587-018 0 –10 –110 –120 FREQUENCY FREQUENCY Figure 13. FFT: fS = 105 MSPS, fIN = 40.9 MHz Figure 16. Two-Tone FFT, Wideband: fS = 105 MSPS, AIN1 = 70.3 MHz, AIN2 = 71.3 MHz Rev. F | Page 9 of 16 AD9432 1.00 100 0.75 dBFS 90 0.50 80 ENCODE = 105MSPS AIN = 50.3MHz 0.25 INL (LSB) 70 60 50 dBc 0 40 –0.25 30 –0.50 20 –70 –60 –50 –40 –30 –20 –10 00587-023 10 0 –80 –0.75 00587-021 WORST-CASE SPURIOUS (dBc and dBFS) 110 –1.00 0 ANALOG INPUT POWER LEVEL (dBFS) Figure 19. Integral Nonlinearity, fS = 105 MSPS Figure 17. Single-Tone SFDR, fS = 105 MSPS, fIN = 50.3 MHz 1.00 3.0 0.75 0.50 2.5 VOLTAGE (V) 0 –0.25 2.0 –0.75 –1.00 00587-024 –0.50 00587-022 DNL (LSB) 0.25 1.5 0 2 4 6 8 CURRENT (mA) Figure 20. Voltage Reference Output vs. Current Load Figure 18. Differential Nonlinearity, fS = 105 MSPS Rev. F | Page 10 of 16 10 AD9432 TERMINOLOGY Analog Bandwidth The analog input frequency at which the spectral power of the fundamental frequency (as determined by the FFT analysis) is reduced by 3 dB. Output Propagation Delay The delay between a differential crossing of ENCODE and ENCODE and the time when all output data bits are within valid logic levels. Aperture Delay The delay between a differential crossing of ENCODE and ENCODE and the instant at which the analog input is sampled. Power Supply Rejection Ratio (PSRR) The ratio of a change in input offset voltage to a change in power supply voltage. Aperture Uncertainty (Jitter) The sample-to-sample variation in aperture delay. Signal-to-Noise and Distortion (SINAD) Ratio The ratio of the rms signal amplitude (set at 1 dB below full scale) to the rms value of the sum of all other spectral components, including harmonics but excluding dc. Differential Nonlinearity (DNL) The deviation of any code from an ideal 1 LSB step. Signal-to-Noise Ratio (SNR) The ratio of the rms signal amplitude (set at 1 dB below full scale) to the rms value of the sum of all other spectral components, excluding the first five harmonics and dc. Effective Number of Bits (ENOB) The effective number of bits (ENOB) is calculated from the measured SNR based on the following equation: ⎛ Full − Scale Amplitude ⎞ ⎟ SNR MEASURED − 1.76 dB + 20 log ⎜ ⎜ Input Amplitude ⎟ ⎠ ⎝ ENOB = 6.02 Encode Pulse Width/Duty Cycle Pulse width high is the minimum amount of time that the encode pulse should be left in the Logic 1 state to achieve the rated performance. Pulse width low is the minimum amount of time that the encode pulse should be left in the Logic 0 state. At a given clock rate, these specifications define an acceptable encode duty cycle. Harmonic Distortion The ratio of the rms signal amplitude fundamental frequency to the rms signal amplitude of a single harmonic component (second, third, and so on); reported in dBc. Integral Nonlinearity (INL) The deviation of the transfer function from a reference line measured in fractions of 1 LSB using a “best straight line” determined by a least square curve fit. Spurious-Free Dynamic Range (SFDR) The ratio of the rms signal amplitude to the rms value of the peak spurious spectral component. The peak spurious component may or may not be a harmonic. May be reported in dBc (degrades as signal level is lowered) or in dBFS (always related back to converter full scale). Two-Tone Intermodulation Distortion Rejection The ratio of the rms value of either input tone (f1, f2) to the rms value of the worst third-order intermodulation product; reported in dBc. Products are located at 2f1 − f2 and 2f2 − f1. Two-Tone SFDR The ratio of the rms value of either input tone (f1, f2) to the rms value of the peak spurious component. The peak spurious component may or may not be an IMD product. May be reported in dBc (degrades as signal level is lowered) or in dBFS (always related back to converter full scale). Worst Other Spur The ratio of the rms signal amplitude to the rms value of the worst spurious component (excluding the second-order and third-order harmonic); reported in dBc. Maximum Conversion Rate The maximum encode rate at which parametric testing is performed. Minimum Conversion Rate The encode rate at which the SNR of the lowest analog signal frequency drops by no more than 3 dB below the guaranteed limit. Rev. F | Page 11 of 16 AD9432 EQUIVALENT CIRCUITS VDD VCC VREFIN 00587-004 00587-007 Dx Figure 24. Digital Output Circuit Figure 21. Voltage Reference Input Circuit VCC VCC 5kΩ 5kΩ 7kΩ 7kΩ AIN VREFOUT 00587-008 00587-005 AIN Figure 25. Analog Input Circuit Figure 22. Voltage Reference Output Circuit VCC 17kΩ 17kΩ 100Ω 100Ω ENCODE ENCODE 8kΩ 00587-006 8kΩ Figure 23. Encode Input Circuit Rev. F | Page 12 of 16 AD9432 THEORY OF OPERATION The AD9432 is a 12-bit pipeline converter that uses a switchedcapacitor architecture. Optimized for high speed, this converter provides flat dynamic performance up to frequencies near Nyquist. DNL transitional errors are calibrated at final test to a typical accuracy of 0.25 LSB or less. Note that the encode inputs cannot be driven directly from PECL level signals (VIHD is 3.5 V maximum). PECL level signals can easily be accommodated by ac coupling, as shown in Figure 27. Good performance is obtained using an MC10EL16 translator in the circuit to drive the encode inputs. ANALOG INPUT AD9432 0.1µF PECL GATE ENCODE 510Ω 510Ω 0.1µF 00587-026 The analog input to the AD9432 is a differential buffer. The input buffer is self-biased by an on-chip resistor divider that sets the dc common-mode voltage to a nominal 3 V (see the Equivalent Circuits section). Rated performance is achieved by driving the input differentially. The minimum input offset voltage is obtained when driving from a source with a low differential source impedance, such as a transformer in ac applications. Capacitive coupling at the inputs increases the input offset voltage by as much as ±25 mV. Driving the ADC single-ended degrades performance. For best dynamic performance, impedances at AIN and AIN should match. ENCODE Figure 27. AC Coupling to Encode Inputs ENCODE VOLTAGE LEVEL DEFINITION The voltage level definitions for driving ENCODE and ENCODE in single-ended and differential mode are shown in Figure 28. ENCODE VIHD VICM Special care was taken in the design of the analog input section of the AD9432 to prevent damage and corruption of data when the input is overdriven. The nominal input range is 2 V p-p. Each analog input is 1 V p-p when driven differentially. ENCODE ENCODE VID VILD VIHS 4.0 VILS 00587-027 0.1µF AIN 3.5 Figure 28. Differential and Single-Ended Input Levels Table 5. Encode Inputs Input Differential Signal Amplitude (VID) High Differential Input Voltage (VIHD) Low Differential Input Voltage (VILD) Common-Mode Input (VICM) High Single-Ended Voltage (VIHS) Low Single-Ended Voltage (VILS) 3.0 AIN 00587-025 2.5 2.0 Min 500 mV Nominal 750 mV Max 3.5 V 0V 1.25 V 2V 0V 1.6 V 3.5 V 0.8 V Figure 26. Full-Scale Analog Input Range ENCODE INPUT Any high speed ADC is extremely sensitive to the quality of the sampling clock provided by the user. A track-and-hold circuit is essentially a mixer, and any noise, distortion, or timing jitter on the clock is combined with the desired signal at the ADC output. For this reason, considerable care has been taken in the design of the encode input of the AD9432, and the user is advised to give commensurate thought to the clock source. The encode input supports differential or single-ended mode and is fully TTL-/CMOS-compatible. Often, the cleanest clock source is a crystal oscillator producing a pure sine wave. In this configuration, or with any roughly symmetrical clock input, the input can be ac-coupled and biased to a reference voltage that also provides the encode. This ensures that the reference voltage is centered on the encode signal. Rev. F | Page 13 of 16 AD9432 DIGITAL OUTPUTS VOLTAGE REFERENCE The digital outputs are 3.3 V (2.7 V to 3.6 V) TTL-/CMOScompatible for lower power consumption. The output data format is twos complement (see Table 6). A stable and accurate 2.5 V voltage reference is built into the AD9432 (VREFOUT). In normal operation, the internal reference is used by strapping Pin 45 to Pin 46 and placing a 0.1 μF decoupling capacitor at VREFIN. Table 6. Twos Complement Output Coding (VREF = 2.5 V) Code +2047 … 0 −1 … −2048 AIN − AIN (V) 1.000 … 0 −0.00049 … −1.000 The input range can be adjusted by varying the reference voltage applied to the AD9432. No appreciable degradation in performance occurs when the reference is adjusted ±5%. The full-scale range of the ADC tracks reference voltage changes linearly. Digital Output 0111 1111 1111 … 0000 0000 0000 1111 1111 1111 … 1000 0000 0000 TIMING The out-of-range (OR) output is logic low for normal operation. During any clock cycle when the ADC output data (Dx) reaches positive or negative full scale (+2047 or −2048), the OR output goes high. The OR output is internally generated each clock cycle. It has the same pipeline latency and propagation delay as the ADC output data and remains high until the output data reflects an in-range condition. The ADC output bits (Dx) do not roll over and, therefore, remain at positive or negative full scale (+2047 or −2048) while the OR output is high. The AD9432 provides latched data outputs, with 10 pipeline delays. Data outputs are included or available one propagation delay (tPD) after the rising edge of the encode command (see Figure 2). The length of the output data lines and the loads placed on them should be minimized to reduce transients within the AD9432; these transients can detract from the dynamic performance of the converter. The minimum guaranteed conversion rate of the AD9432 is 1 MSPS. At internal clock rates below 1 MSPS, dynamic performance may degrade. Therefore, input clock rates below 1 MHz should be avoided. During initial power-up, or whenever the clock to the AD9432 is interrupted, the output data will not be accurate for 200 ns or 10 clock cycles, whichever is longer. Rev. F | Page 14 of 16 AD9432 APPLICATIONS INFORMATION 66 USING THE AD8138 TO DRIVE THE AD9432 The AD8138 differential output op amp can be used to drive the AD9432 in dc-coupled applications. The AD8138 was specifically designed for ADC driver applications. Superior SNR performance is maintained up to analog frequencies of 30 MHz. The AD8138 op amp provides single-ended-to-differential conversion, which allows for a low cost alternative to transformer coupling for ac applications, as well. 65 SNR/SINAD (dB) SNR The circuit in Figure 29 was breadboarded, and the measured performance is shown in Figure 30 and Figure 31. These figures are for ±5 V supplies at the AD8138; with a single 5 V supply at the AD8138, performance dropped by about 1 dB to 2 dB. 00587-029 –70 H2 H3 –90 00587-030 HARMONICS (dB) –80 0 22pF 20 40 60 AIN (MHz) 50Ω Figure 31. Measured Second-Order and Third-Order Harmonic Distortion (Encode = 105 MSPS) AIN 5V 2kΩ 500Ω 3kΩ 0.1µF 00587-028 10pF 60 Figure 30. Measured SNR and SINAD (Encode = 105 MSPS) –100 AD8138 500Ω 40 AIN VOCM 25Ω 20 AIN (MHz) AD9432 500Ω 50Ω 62 0 500Ω 50Ω SINAD 60 The dc common-mode voltage for the AD8138 outputs can be adjusted via the VOCM input to provide the 3 V common-mode voltage that the AD9432 inputs require. VIN 63 61 Figure 30 shows SNR and SINAD for a −1 dBFS analog input frequency varied from 2 MHz to 40 MHz with an encode rate of 105 MSPS. The measurements are for nominal conditions at room temperature. Figure 31 shows the second-order and third-order harmonic distortion performance under the same conditions. 10pF 64 Figure 29. AD8138/AD9432 Schematic Rev. F | Page 15 of 16 AD9432 OUTLINE DIMENSIONS 0.75 0.60 0.45 12.20 12.00 SQ 11.80 1.60 MAX 52 40 39 1 PIN 1 10.20 10.00 SQ 9.80 TOP VIEW (PINS DOWN) 1.45 1.40 1.35 0.15 0.05 0.20 0.09 7° 3.5° 0° SEATING PLANE 13 27 14 0.10 COPLANARITY VIEW A VIEW A 26 0.38 0.32 0.22 0.65 BSC LEAD PITCH 051706-A ROTATED 90° CCW COMPLIANT TO JEDEC STANDARDS MS-026-BCC Figure 32. 52-Lead Low Profile Quad Flat Package [LQFP] (ST-52) Dimensions shown in millimeters 1.20 MAX 12.00 BSC SQ 52 0.15 0.05 0.20 0.09 7° 3.5° 0° 0.08 MAX COPLANARITY 1 PIN 1 10.00 BSC SQ TOP VIEW 0° MIN 39 39 (PINS DOWN) 1.05 1.00 0.95 52 40 40 1 SEATING PLANE 7.30 BSC SQ EXPOSED PAD BOTTOM VIEW 13 27 14 26 VIEW A (PINS UP) 27 26 0.65 BSC LEAD PITCH 0.38 0.32 0.22 VIEW A ROTATED 90° CCW 13 14 COMPLIANT TO JEDEC STANDARDS MS-026-ACC FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. 072508-A 0.75 0.60 0.45 Figure 33. 52-Lead Thin Quad Flat Package, Exposed Pad [TQFP_EP] (SV-52-2) Dimensions shown in millimeters ORDERING GUIDE Model AD9432BSTZ-801 AD9432BSTZ-1051 AD9432BSVZ-801 AD9432BSVZ-1051 1 Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Package Description 52-Lead Low Profile Quad Flat Package [LQFP] 52-Lead Low Profile Quad Flat Package [LQFP] 52-Lead Thin Quad Flat Package, Exposed Pad [TQFP_EP] 52-Lead Thin Quad Flat Package, Exposed Pad [TQFP_EP] Z = RoHS Compliant Part. ©2002–2009 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00587-0-6/09(F) Rev. F | Page 16 of 16 Package Option ST-52 ST-52 SV-52-2 SV-52-2