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14-Bit, 170 MSPS/210 MSPS/250 MSPS, 1.8 V Dual Analog-to-Digital Converter (ADC) AD9643
FEATURES
SNR = 70.6 dBFS at 185 MHz AIN and 250 MSPS SFDR = 85 dBc at 185 MHz AIN and 250 MSPS -151.6 dBFS/Hz input noise at 185 MHz, -1 dBFS AIN and 250 MSPS Total power consumption: 785 mW at 250 MSPS 1.8 V supply voltages LVDS (ANSI-644 levels) outputs Integer 1-to-8 input clock divider (625 MHz maximum input) Sample rates of up to 250 MSPS IF sampling frequencies of up to 400 MHz Internal ADC voltage reference Flexible analog input range 1.4 V p-p to 2.0 V p-p (1.75 V p-p nominal) ADC clock duty cycle stabilizer 95 dB channel isolation/crosstalk Serial port control Energy saving power-down modes User-configurable, built-in self-test (BIST) capability
FUNCTIONAL BLOCK DIAGRAM
AVDD AGND DRVDD
VIN+A VIN-A VCM VIN+B VIN-B REFERENCE
PIPELINE 14-BIT ADC
14 PARALLEL DDR LVDS AND DRIVERS
D0
AD9643
PIPELINE 14-BIT ADC 14
. . . . .
D13 DCO OR
SERIAL PORT
1 TO 8 CLOCK DIVIDER
OEB PDWN
SCLK SDIO CSB CLK+ CLK- SYNC NOTES 1. THE D0 TO D13 PINS REPRESENT BOTH THE CHANNEL A AND CHANNE L B LVDS OUTPUT DATA.
Figure 1.
APPLICATIONS
Communications Diversity radio systems Multimode digital receivers (3G) TD-SCDMA, WiMax, WCDMA, CDMA2000, GSM, EDGE, LTE I/Q demodulation systems Smart antenna systems General-purpose software radios Ultrasound equipment Broadband data applications
GENERAL DESCRIPTION
The AD9643 is a dual, 14-bit analog-to-digital converter (ADC) with sampling speeds of up to 250 MSPS. The AD9643 is designed to support communications applications, where low cost, small size, wide bandwidth, and versatility are desired. The dual ADC cores feature a multistage, differential pipelined architecture with integrated output error correction logic. Each ADC features wide bandwidth inputs supporting a variety of user-selectable input ranges. An integrated voltage reference eases design considerations. A duty cycle stabilizer is provided to compensate for variations in the ADC clock duty cycle, allowing the converters to maintain excellent performance. The ADC output data is routed directly to the two external 14-bit LVDS output ports and formatted as either interleaved or channel multiplexed. Flexible power-down options allow significant power savings, when desired.
Rev. A
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.
Programming for setup and control are accomplished using a 3-wire SPI-compatible serial interface. The AD9643 is available in a 64-lead LFCSP and is specified over the industrial temperature range of -40C to +85C. This product is protected by a U.S. patent.
PRODUCT HIGHLIGHTS
1. Integrated dual, 14-bit, 170 MSPS/210 MSPS/250 MSPS ADCs. 2. Operation from a single 1.8 V supply and a separate digital output driver supply accommodating LVDS outputs. 3. Proprietary differential input maintains excellent SNR performance for input frequencies of up to 400 MHz. 4. SYNC input allows synchronization of multiple devices. 5. 3-pin, 1.8 V SPI port for register programming and register readback. 6. Pin compatibility with the AD9613, allowing a simple migration down from 14 bits to 12 bits. This part is also pin compatible with the AD6649 and the AD6643.
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 (c)2011 Analog Devices, Inc. All rights reserved.
09636-001
AD9643 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications ....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Product Highlights ........................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 ADC DC Specifications ............................................................... 3 ADC AC Specifications ............................................................... 4 Digital Specifications ................................................................... 6 Switching Specifications .............................................................. 8 Timing Specifications .................................................................. 9 Absolute Maximum Ratings.......................................................... 11 Thermal Characteristics ............................................................ 11 ESD Caution ................................................................................ 11 Pin Configurations and Function Descriptions ......................... 12 Typical Performance Characteristics ........................................... 16 Equivalent Circuits ......................................................................... 22 Theory of Operation ...................................................................... 23 ADC Architecture ...................................................................... 23 Analog Input Considerations ................................................... 23 Voltage Reference ....................................................................... 25 Clock Input Considerations ...................................................... 25 Power Dissipation and Standby Mode .................................... 26 Digital Outputs ........................................................................... 27 Channel/Chip Synchronization .................................................... 28 Serial Port Interface (SPI) .............................................................. 29 Configuration Using the SPI ..................................................... 29 Hardware Interface..................................................................... 29 SPI Accessible Features .............................................................. 30 Memory Map .................................................................................. 31 Reading the Memory Map Register Table............................... 31 Memory Map Register Table ..................................................... 32 Memory Map Register Description ......................................... 34 Applications Information .............................................................. 35 Design Guidelines ...................................................................... 35 Outline Dimensions ....................................................................... 36 Ordering Guide .......................................................................... 36
REVISION HISTORY
5/11--Rev. 0 to Rev. A Changes to Table 2, Worst Other (Harmonic or Spur) Max Values......................................................................................... 4 4/11--Revision 0: Initial Version
Rev. A | Page 2 of 36
AD9643 SPECIFICATIONS
ADC DC SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = -1.0 dBFS differential input, 1.75 V p-p full-scale input range, duty cycle stabilizer (DCS) enabled, unless otherwise noted. Table 1.
Parameter RESOLUTION ACCURACY No Missing Codes Offset Error Gain Error Differential Nonlinearity (DNL) Integral Nonlinearity (INL) 1 MATCHING CHARACTERISTIC Offset Error Gain Error TEMPERATURE DRIFT Offset Error Gain Error INPUT REFERRED NOISE VREF = 1.0 V ANALOG INPUT Input Span Input Capacitance 2 Input Resistance 3 Input Common-Mode Voltage POWER SUPPLIES Supply Voltage AVDD DRVDD Supply Current IAVDD1 IDRVDD1 POWER CONSUMPTION Sine Wave Input (DRVDD = 1.8 V) Standby Power 4 Power-Down Power
1 2 3
Temperature Full Full Full Full Full 25C Full 25C Full Full
Min 14
AD9643-170 Typ Max
Min 14
AD9643-210 Typ Max
Min 14
AD9643-250 Typ Max
Unit Bits
Guaranteed 10 +2/-6 0.75 0.25 1.8 1.5 13 2.5/ +3.5 15 50 1.33 1.75 2.5 20 0.9
Guaranteed 10 +3/-5 0.75 0.25 2 1.5 13 -2/ +3.5 15 50 1.33 1.75 2.5 20 0.9
Guaranteed 10 4 0.75 0.25 3.5 1.5 13 -2.5/ +3.5 15 50 1.33 1.75 2.5 20 0.9 mV %FSR LSB LSB LSB LSB mV %FSR
Full Full 25C Full Full Full Full
ppm/C ppm/C LSB rms V p-p pF k V
Full Full Full Full Full Full Full
1.7 1.7
1.8 1.8 196 145 614 90 10
1.9 1.9 250 160
1.7 1.7
1.8 1.8 217 160 680 90 10
1.9 1.9 265 185
1.7 1.7
1.8 1.8 256 180 785 90 10
1.9 1.9 275 210
V V mA mA mW mW mW
Measured with a low input frequency, full-scale sine wave. Input capacitance refers to the effective capacitance between one differential input pin and its complement. Input resistance refers to the effective resistance between one differential input pin and its complement. 4 Standby power is measured with a dc input and the CLK pin inactive (that is, set to AVDD or AGND).
Rev. A | Page 3 of 36
AD9643
ADC AC SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = -1.0 dBFS differential input, 1.75 V p-p full-scale input range, unless otherwise noted. Table 2.
Parameter 1 SIGNAL-TO-NOISE-RATIO (SNR) fIN = 30 MHz fIN = 90 MHz fIN = 140 MHz fIN = 185 MHz fIN = 220 MHz SIGNAL-TO-NOISE AND DISTORTION (SINAD) fIN = 30 MHz fIN = 90 MHz fIN = 140 MHz fIN = 185 MHz fIN = 220 MHz EFFECTIVE NUMBER OF BITS (ENOB) fIN = 30 MHz fIN = 90 MHz fIN = 140 MHz fIN = 185 MHz fIN = 220 MHz WORST SECOND OR THIRD HARMONIC fIN = 30 MHz fIN = 90 MHz fIN = 140 MHz fIN = 185 MHz fIN = 220 MHz SPURIOUS-FREE DYNAMIC RANGE (SFDR) fIN = 30 MHz fIN = 90 MHz fIN = 140 MHz fIN = 185 MHz fIN = 220 MHz WORST OTHER (HARMONIC OR SPUR) fIN = 30 MHz fIN = 90 MHz fIN = 140 MHz fIN = 185 MHz fIN = 220 MHz TWO-TONE SFDR fIN = 184.12 MHz (-7 dBFS ), 187.12 MHz (-7 dBFS ) Temperature 25C 25C Full 25C 25C Full 25C 71.1 70.9 Min AD9643-170 Typ Max 72.2 72.0 70.4 71.8 71.4 69.9 71.6 71.2 68.8 70.5 71.4 70.9 Min AD9643-210 Typ Max 72.2 72.0 Min AD9643-250 Typ Max 72.0 71.7 Unit dBFS dBFS dBFS dBFS dBFS dBFS dBFS
25C 25C Full 25C 25C Full 25C 25C 25C 25C 25C 25C 25C 25C Full 25C 25C Full 25C
71.2 71.0 70.4 70.8 70.4 70.1 11.5 11.5 11.5 11.4 11.4 -95 -92 -78 -88 -83 -83 69.9
71.2 71.0 70.6 70.2 67.5 69.9 11.5 11.5 11.5 11.4 11.3 -90 -90 -80 -88 -87 -85
71.0 70.7 70.4 69.9 69.5 11.5 11.5 11.4 11.3 11.3 -90 -88 -85 -85 -80 -85
dBFS dBFS dBFS dBFS dBFS dBFS dBFS Bits Bits Bits Bits Bits dBc dBc dBc dBc dBc dBc dBc
25C 25C Full 25C 25C Full 25C 25C 25C Full 25C 25C Full 25C 25C
95 92 78 88 83 83 -98 -97 -78 -97 -96 -94 88 80
90 90 88 87 80 85 -95 -95 -80 -93 -92 -90 88
90 88 86 85 85 -94 -93 -92 -92 -80 -88 88
dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc
Rev. A | Page 4 of 36
AD9643
Parameter 1 CROSSTALK 2 FULL POWER BANDWIDTH 3 NOISE BANDWIDTH 4
1 2
Temperature Full 25C 25C
Min
AD9643-170 Typ Max 95 400 1000
Min
AD9643-210 Typ Max 95 400 1000
Min
AD9643-250 Typ Max 95 400 1000
Unit dB MHz MHz
See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions. Crosstalk is measured at 100 MHz with -1.0 dBFS on one channel and no input on the alternate channel. 3 Full power bandwidth is the bandwidth of operation in which proper ADC performance can be achieved. 4 Noise bandwidth is the -3 dB bandwidth for the ADC inputs across which noise can enter the ADC and is not attenuated internally.
Rev. A | Page 5 of 36
AD9643
DIGITAL SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 1.8 V, maximum sample rate, VIN = -1.0 dBFS differential input, 1.75 V p-p full-scale input range, DCS enabled, unless otherwise noted. Table 3.
Parameter DIFFERENTIAL CLOCK INPUTS (CLK+, CLK-) Logic Compliance Internal Common-Mode Bias Differential Input Voltage Input Voltage Range Input Common-Mode Range High Level Input Current Low Level Input Current Input Capacitance Input Resistance SYNC INPUT Logic Compliance Internal Bias Input Voltage Range High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Capacitance Input Resistance LOGIC INPUT (CSB) 1 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUT (SCLK) 2 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUTS (SDIO)1 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance LOGIC INPUTS (OEB, PDWN)2 High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current Input Resistance Input Capacitance
Rev. A | Page 6 of 36
Temp
Min
Typ
Max
Unit
Full Full Full Full Full Full Full Full
CMOS/LVDS/LVPECL 0.9 0.3 3.6 AGND AVDD 0.9 1.4 -10 +22 -22 -10 4 8 10 12 CMOS/LVDS 0.9 AGND 1.2 AGND -5 -5 12 1.22 0 -5 -80 26 2 1.22 0 45 -5 26 2 1.22 0 45 -5 26 5 1.22 0 45 -5 26 5 2.1 0.6 70 +5 2.1 0.6 70 +5 2.1 0.6 70 +5 1 16 AVDD AVDD 0.6 +5 +5 20 2.1 0.6 +5 -45
V V p-p V V A A pF k
Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full
V V V V A A pF k V V A A k pF V V A A k pF V V A A k pF V V A A k pF
AD9643
Parameter DIGITAL OUTPUTS LVDS Data and OR Outputs Differential Output Voltage (VOD), ANSI Mode Output Offset Voltage (VOS), ANSI Mode Differential Output Voltage (VOD), Reduced Swing Mode Output Offset Voltage (VOS), Reduced Swing Mode
1 2
Temp
Min
Typ
Max
Unit
Full Full Full Full
250 1.15 150 1.15
350 1.25 200 1.25
450 1.35 280 1.35
mV V mV V
Pull-up. Pull-down.
Rev. A | Page 7 of 36
AD9643
SWITCHING SPECIFICATIONS
Table 4.
Parameter CLOCK INPUT PARAMETERS Input Clock Rate Conversion Rate 1 CLK Period--Divide-by-1 Mode (tCLK) CLK Pulse Width High (tCH) Divide-by-1 Mode, DCS Enabled Divide-by-1 Mode, DCS Disabled Divide-by-2 Mode Through Divide-by-8 Mode Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) DATA OUTPUT PARAMETERS LVDS Mode Data Propagation Delay (tPD) DCO Propagation Delay (tDCO) DCO-to-Data Skew (tSKEW) Pipeline Delay (Latency) Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) Wake-Up Time (from Standby) Wake-Up Time (from Power-Down) Out-of-Range Recovery Time
1
Temp Full Full Full Full Full Full Full Full
Min
AD9643-170 Typ Max 625 170
Max
AD9643-210 Typ Max 625 210
Min
AD9643-250 Typ Max 625 250
Unit MHz MSPS ns ns ns ns ns ps rms
40 5.8 2.61 2.76 0.8 2.9 2.9
40 4.8 2.16 2.28 0.8 2.4 2.4
40 4 1.8 1.9 0.8 2.0 2.0
3.19 3.05
2.64 2.52
2.2 2.1
1.0 0.1
1.0 0.1
1.0 0.1
Full Full Full Full Full Full Full Full Full
0.1
4.8 5.5 0.7 10 1.0 0.1 10 250 3
1.3
0.1
4.8 5.5 0.7 10 1.0 0.1 10 250 3
1.3
0.1
4.8 5.5 0.7 10 1.0 0.1 10 250 3
1.3
ns ns ns Cycles ns ps rms s s Cycles
Conversion rate is the clock rate after the divider.
Rev. A | Page 8 of 36
AD9643
TIMING SPECIFICATIONS
Table 5.
Parameter SYNC TIMING REQUIREMENTS tSSYNC tHSYNC SPI TIMING REQUIREMENTS tDS tDH tCLK tS tH tHIGH tLOW tEN_SDIO tDIS_SDIO Conditions SYNC to the rising edge of CLK setup time SYNC to the rising edge of CLK hold time Setup time between the data and the rising edge of SCLK Hold time between the data and the rising edge of SCLK Period of the SCLK Setup time between CSB and SCLK Hold time between CSB and SCLK Minimum period that SCLK should be in a logic high state Minimum period that SCLK should be in a logic low state 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 10 Min Typ 0.3 0.4 Max Unit ns ns ns ns ns ns ns ns ns ns ns
Rev. A | Page 9 of 36
AD9643
Timing Diagrams
tA
N-1 N VIN N+1 N+2 N+4 N+5 N+3
tCH
CLK+ CLK-
tCLK
tDCO
DCO- DCO+
tSKEW tPD
CH A N - 10 CH B N - 10 CH A N-9 CH B N-9 CH A N-8 CH B N-8 CH A N-7 CH B N-7 CH A N-6
PARALLEL INTERLEAVED
D0 (LSB)
CHANNEL A AND CHANNEL B
. . .
D13 (MSB)
CH A N - 10
CH B N - 10
CH A N-9
CH B N-9
CH A N-8
CH B N-8
CH A N-7
CH B N-7
CH A N-6
CHANNEL MULTIPLEXED D0/D1 (EVEN/ODD) MODE (LSB) CHANNEL A
. . .
CH A0 N - 10
CH A1 N - 10
CH A0 N-9
CH A1 N-9
CH A0 N-8
CH A1 N-8
CH A0 N-7
CH A1 N-7
CH A0 N-6
D12/D13 (MSB) CHANNEL MULTIPLEXED (EVEN/ODD) MODE D0/D1 (LSB)
CH A12 N - 10 CH B0 N - 10
CH A13 N - 10 CH B1 N - 10
CH A12 N-9 CH B0 N-9
CH A13 N-9 CH B1 N-9
CH A12 N-8 CH B0 N-8
CH A13 N-8 CH B1 N-8
CH A12 N-7 CH B0 N-7
CH A13 N-7 CH B1 N-7
CH A12 N-6 CH B0 N-6
CHANNEL B
. . .
CH B12 N - 10
CH B13 N - 10
CH B12 N-9
CH B13 N-9
CH B12 N-8
CH B13 N-8
CH B12 N-7
CH B13 N-7
CH B12 N-6
Figure 2. LVDS Modes for Data Output Timing
CLK+
tSSYNC
SYNC
tHSYNC
09636-003
Figure 3. SYNC Timing Inputs
Rev. A | Page 10 of 36
09636-002
D12/D13 (MSB)
AD9643 ABSOLUTE MAXIMUM RATINGS
Table 6.
Parameter Electrical AVDD to AGND DRVDD to AGND VIN+A/VIN+B, VIN-A/VIN-B to AGND CLK+, CLK- to AGND SYNC to AGND VCM to AGND CSB to AGND SCLK to AGND SDIO to AGND OEB to AGND PDWN to AGND OR+/OR- to AGND D0-/D0+ Through D13-/D13+ to AGND DCO+/DCO- to AGND Environmental Operating Temperature Range (Ambient) Maximum Junction Temperature Under Bias Storage Temperature Range (Ambient) Rating -0.3 V to +2.0 V -0.3 V to +2.0 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 -0.3 V to DRVDD + 0.3 V -0.3 V to DRVDD + 0.3 V -40C to +85C 150C -65C to +125C
THERMAL CHARACTERISTICS
The exposed paddle must be soldered to the ground plane for the LFCSP package. This increases the reliability of the solder joints, maximizing the thermal capability of the package. Table 7. Thermal Resistance
Airflow Velocity (m/sec) 0 1.0 2.0
Package Type 64-Lead LFCSP 9 mm x 9 mm (CP-64-4)
1 2 3
JA1, 2 26.8 21.6 20.2
JC1, 3 1.14
JB1, 4 10.4
Unit C/W C/W C/W
Per JEDEC 51-7, plus JEDEC 25-5 2S2P test board. Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air). Per MIL-Std 883, Method 1012.1. 4 Per JEDEC JESD51-8 (still air).
Typical JA is specified for a 4-layer PCB with a solid ground plane. As shown in Table 7, airflow increases heat dissipation, which reduces JA. In addition, metal in direct contact with the package leads from metal traces, through holes, ground, and power planes, reduces the JA.
ESD CAUTION
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Rev. A | Page 11 of 36
AD9643 PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
PIN 1 INDICATOR CLK+ CLK- SYNC DNC DNC DNC DNC (LSB) D0- (LSB) D0+ DRVDD D1- D1+ D2- D2+ D3- D3+ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AVDD AVDD VIN+B VIN-B AVDD AVDD DNC VCM DNC DNC AVDD AVDD VIN-A VIN+A AVDD AVDD
AD9643
PARALLEL LVDS TOP VIEW (Not to Scale)
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
PDWN OEB CSB SCLK SDIO OR+ OR- D13+ (MSB) D13- (MSB) D12+ D12- DRVDD D11+ D11- D10+ D10-
NOTES 1. DNC = DO NOT CONNECT. DO NOT CONNECT TO THIS PIN. 2. THE EXPOSED THERMAL PADDLE ON THE BOTTOM OF THE PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART. THIS EXPOSED PADDLE MUST BE CONNECTED TO GROUND FOR PROPER OPERATION.
D4- D4+ DRVDD D5- D5+ D6- D6+ DCO- DCO+ D7- D7+ DRVDD D8- D8+ D9- D9+
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Figure 4. LFCSP Interleaved Parallel LVDS Pin Configuration (Top View)
Table 8. Pin Function Descriptions for Interleaved Parallel LVDS Mode
Pin No. ADC Power Supplies 10, 19, 28, 37 49, 50, 53, 54, 59, 60, 63, 64 4, 5, 6, 7, 55, 56, 58 0 Mnemonic DRVDD AVDD DNC AGND, Exposed Paddle Type Supply Supply Ground Description Digital Output Driver Supply (1.8 V Nominal). Analog Power Supply (1.8 V Nominal). Do Not Connect. Do not connect to this pin. Analog Ground. The exposed thermal paddle on the bottom of the package provides the analog ground for the part. This exposed paddle must be connected to ground for proper operation. Differential Analog Input Pin (+) for Channel A. Differential Analog Input Pin (-) for Channel A. Differential Analog Input Pin (+) for Channel B. Differential Analog Input Pin (-) for Channel B. Common-Mode Level Bias Output for Analog Inputs. This pin should be decoupled to ground using a 0.1 F capacitor. ADC Clock Input--True. ADC Clock Input--Complement. Digital Synchronization Pin. Slave mode only. Channel A/Channel B LVDS Output Data 0--True. Channel A/Channel B LVDS Output Data 0--Complement. Channel A/Channel B LVDS Output Data 1--True. Channel A/Channel B LVDS Output Data 1--Complement. Channel A/Channel B LVDS Output Data 2--True. Channel A/Channel B LVDS Output Data 2--Complement. Channel A/Channel B LVDS Output Data 3--True. Channel A/Channel B LVDS Output Data 3--Complement. Channel A/Channel B LVDS Output Data 4--True.
ADC Analog 51 52 62 61 57 1 2 Digital Input 3 Digital Outputs 9 8 12 11 14 13 16 15 18
VIN+A VIN-A VIN+B VIN-B VCM CLK+ CLK- SYNC D0+ (LSB) D0- (LSB) D1+ D1- D2+ D2- D3+ D3- D4+
Input Input Input Input Output Input Input Input Output Output Output Output Output Output Output Output Output
Rev. A | Page 12 of 36
09636-004
AD9643
Pin No. 17 21 20 23 22 27 26 30 29 32 31 34 33 36 35 39 38 41 40 43 42 25 24 SPI Control 45 44 46 Output Enable and Power-Down 47 48 Mnemonic D4- D5+ D5- D6+ D6- D7+ D7- D8+ D8- D9+ D9- D10+ D10- D11+ D11- D12+ D12- D13+ (MSB) D13- (MSB) OR+ OR- DCO+ DCO- SCLK SDIO CSB OEB PDWN Type Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Input Input/Output Input Input/Output Input/Output Description Channel A/Channel B LVDS Output Data 4--Complement. Channel A/Channel B LVDS Output Data 5--True. Channel A/Channel B LVDS Output Data 5--Complement. Channel A/Channel B LVDS Output Data 6--True. Channel A/Channel B LVDS Output Data 6--Complement. Channel A/Channel B LVDS Output Data 7--True. Channel A/Channel B LVDS Output Data 7--Complement. Channel A/Channel B LVDS Output Data 8--True. Channel A/Channel B LVDS Output Data 8--Complement. Channel A/Channel B LVDS Output Data 9--True. Channel A/Channel B LVDS Output Data 9--Complement. Channel A/Channel B LVDS Output Data 10--True. Channel A/Channel B LVDS Output Data 10--Complement. Channel A/Channel B LVDS Output Data 11--True. Channel A/Channel B LVDS Output Data 11--Complement. Channel A/Channel B LVDS Output Data 12--True. Channel A/Channel B LVDS Output Data 12--Complement. Channel A/Channel B LVDS Output Data 13--True. Channel A/Channel B LVDS Output Data 13--Complement. Channel A/Channel B LVDS Overrange--True. Channel A/Channel B LVDS Overrange--Complement. Channel A/Channel B LVDS Data Clock Output--True. Channel A/Channel B LVDS Data Clock Output--Complement. SPI Serial Clock. SPI Serial Data I/O. SPI Chip Select (Active Low). Output Enable Input (Active Low). Power-Down Input (Active High). The operation of this pin depends on the SPI mode and can be configured as power-down or standby (see Table 14).
Rev. A | Page 13 of 36
AD9643
PIN 1 INDICATOR CLK+ CLK- SYNC DNC DNC DNC DNC (LSB) B D0-/D1- (LSB) B D0+/D1+ DRVDD B D2-/D3- B D2+/D3+ B D4-/D5- B D4+/D5+ B D6-/D7- B D6+/D7+ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 AVDD AVDD VIN+B VIN-B AVDD AVDD DNC VCM DNC DNC AVDD AVDD VIN-A VIN+A AVDD AVDD
AD9643
CHANNEL MULTIPLEXED (EVEN/ODD) LVDS TOP VIEW (Not to Scale)
48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33
PDWN OEB CSB SCLK SDIO OR+ OR- A D12+/D13+ (MSB) A D12-/D13- (MSB) A D10+/D11+ A D10-/D11- DRVDD A D8+/D9+ A D8-/D9- A D6+/D7+ A D6-/D7-
NOTES 1. DNC = DO NOT CONNECT. DO NOT CONNECT TO THIS PIN. 2. THE EXPOSED THERMAL PADDLE ON THE BOTTOM OF THE PACKAGE PROVIDES THE ANALOG GROUND FOR THE PART. THIS EXPOSED PADDLE MUST BE CONNECTED TO GROUND FOR PROPER OPERATION.
B D8-/D9- B D8+/D9+ DRVDD B D10-/D11- B D10+/D11+ (MSB) B D12-/D13- (MSB) B D12+/D13+ DCO- DCO+ (LSB) A D0-/D1- (LSB) A D0+/D1+ DRVDD A D2-/D3- A D2+/D3+ A D4-/D5- A D4+/D5+
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Figure 5. LFCSP Channel Multiplexed (Even/Odd) LVDS Pin Configuration (Top View)
Table 9. Pin Function Descriptions for Channel Multiplexed (Even/Odd) LVDS Mode
Pin No. ADC Power Supplies 10, 19, 28, 37 49, 50, 53, 54, 59, 60, 63, 64 4, 5, 6, 7 0 Mnemonic DRVDD AVDD DNC AGND, Exposed Paddle Type Supply Supply Ground Description Digital Output Driver Supply (1.8 V Nominal). Analog Power Supply (1.8 V Nominal). Do Not Connect. Do not connect to this pin. Analog Ground. The exposed thermal paddle on the bottom of the package provides the analog ground for the part. This exposed paddle must be connected to ground for proper operation. Differential Analog Input Pin (+) for Channel A. Differential Analog Input Pin (-) for Channel A. Differential Analog Input Pin (+) for Channel B. Differential Analog Input Pin (-) for Channel B. Do Not Connect. Do not connect to this pin. Do Not Connect. Do not connect to this pin. Do Not Connect. Do not connect to this pin. Common-Mode Level Bias Output for Analog Inputs. This pin should be decoupled to ground using a 0.1 F capacitor. ADC Clock Input--True. ADC Clock Input--Complement. Digital Synchronization Pin. Slave mode only. Channel B LVDS Output Data 0/Data 1--Complement. Channel B LVDS Output Data 0/Data 1--True. Channel B LVDS Output Data 2/Data 3--Complement. Channel B LVDS Output Data 2/Data 3--True. Channel B LVDS Output Data 4/Data 5--Complement.
ADC Analog 51 52 62 61 55 56 58 57 1 2 Digital Input 3 Digital Outputs 8 9 11 12 13
VIN+A VIN-A VIN+B VIN-B DNC DNC DNC VCM CLK+ CLK- SYNC B D0-/D1- (LSB) B D0+/D1+ (LSB) B D2-/D3- B D2+/D3+ B D4-/D5-
Input Input Input Input
Output Input Input Input Output Output Output Output Output
Rev. A | Page 14 of 36
09636-005
AD9643
Pin No. 14 15 16 17 18 20 21 22 23 26 27 29 30 31 32 33 34 35 36 38 39 40 41 43 42 25 24 SPI Control 45 44 46 Output Enable and Power-Down 47 48 Mnemonic B D4+/D5+ B D6-/D7- B D6+/D7+ B D8-/D9- B D8+/D9+ B D10-/D11- B D10+/D11+ B D12-/D13- (MSB) B D12+/D13+ (MSB) A D0-/D1- (LSB) A D0+/D1+ (LSB) A D2-/D3- A D2+/D3+ A D4-/D5- A D4+/D5+ A D6-/D7- A D6+/D7+ A D8-/D9- A D8+/D9+ A D10-/D11- A D10+/D11+ A D12-/D13- (MSB) A D12+/D13+ (MSB) OR+ OR- DCO+ DCO- SCLK SDIO CSB OEB PDWN Type Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Output Input Input/Output Input Input Input Description Channel B LVDS Output Data 4/Data 5--True. Channel B LVDS Output Data 6/Data 7--Complement. Channel B LVDS Output Data 6/Data 7--True. Channel B LVDS Output Data 8/Data 9--Complement. Channel B LVDS Output Data 8/Data 9--True. Channel B LVDS Output Data 10/Data 11--Complement. Channel B LVDS Output Data 10/Data 11--True. Channel B LVDS Output Data 12/Data 13--Complement. Channel B LVDS Output Data 12/Data 13--True. Channel A LVDS Output Data 0/Data 1--Complement. Channel A LVDS Output Data 0/Data 1--True. Channel A LVDS Output Data 2/Data 3--Complement. Channel A LVDS Output Data 2/Data 3--True. Channel A LVDS Output Data 4/Data 5--Complement. Channel A LVDS Output Data 4/Data 5--True. Channel A LVDS Output Data 6/Data 7--Complement. Channel A LVDS Output Data 6/Data 7--True. Channel A LVDS Output Data 8/Data 9--Complement. Channel A LVDS Output Data 8/Data 9--True. Channel A LVDS Output Data 10/Data 11--Complement. Channel A LVDS Output Data 10/Data 11--True. Channel A LVDS Output Data 12/Data 13--Complement. Channel A LVDS Output Data 12/Data 13--True. Channel A/Channel B LVDS Overrange Output--True. Channel A/Channel B LVDS Overrange Output--Complement. Channel A/Channel B LVDS Data Clock Output--True. Channel A/Channel B LVDS Data Clock Output--Complement. SPI Serial Clock. SPI Serial Data Input/Output. SPI Chip Select (Active Low). Output Enable Input (Active Low). Power-Down Input (Active High). The operation of this pin depends on the SPI mode and can be configured as powerdown or standby (see Table 14).
Rev. A | Page 15 of 36
AD9643 TYPICAL PERFORMANCE CHARACTERISTICS
AVDD = 1.8 V, DRVDD = 1.8 V, sample rate = 250 MSPS, DCS enabled, 1.75 V p-p differential input, VIN = -1.0 dBFS, 32k sample, TA = 25C, unless otherwise noted.
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 170MSPS 90.1MHz @ -1dBFS SNR = 70.8dB (71.8dBFS) SFDR = 88dBc
120 SFDR (dBFS) 100
SNR/SFDR (dBc AND dBFS)
80
SNR (dBFS)
60 SFDR (dBc) 40 SNR (dBc) 20
SECOND HARMONIC
THIRD HARMONIC
09636-013
0
10
20
30 40 50 60 FREQUENCY (MHz)
70
80
-90
-80
-70 -60 -50 -40 -30 INPUT AMPLITUDE (dBFS)
-20
-10
0
Figure 6. AD9643-170 Single-Tone FFT with fIN = 90.1 MHz
Figure 9. AD9643-170 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 90.1 MHz
100
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 170MSPS 185.1MHz @ -1dBFS SNR = 69.8dB (70.8dBFS) SFDR = 85dBc
SFDR (dBc) 95
SNR/SFDR (dBc AND dBFS)
90 85 80 75 SNR (dBFS) 70 65
THIRD HARMONIC SECOND HARMONIC
09636-014
0
10
20
30 40 50 FREQUENCY (MHz)
60
70
80
90
120 150 180 210 240 270 300 FREQUENCY (MHz)
330 360 390
Figure 7. AD9643-170 Single-Tone FFT with fIN = 185.1 MHz
Figure 10. AD9643-170 Single-Tone SNR/SFDR vs. Input Frequency (fIN)
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 SECOND HARMONIC THIRD HARMONIC 170MSPS 305.1MHz @ -1dBFS SNR = 68.3dB (69.3dBFS) SFDR = 79dBc
0
-20
SFDR/IMD3 (dBc AND dBFS)
SFDR (dBc) -40 IMD3 (dBc) -60
-80 SFDR (dBFS) -100 IMD3 (dBFS)
09636-015
0
10
20
30 40 50 FREQUENCY (MHz)
60
70
80
-78.5
-67.0 -55.5 -44.0 -32.5 INPUT AMPLITUDE (dBFS)
-21.0
-7.0
Figure 8. AD9643-170 Single-Tone FFT with fIN = 305.1 MHz
Figure 11. AD9643-170 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 89.12, fIN2 = 92.12 MHz, fS = 170 MSPS
Rev. A | Page 16 of 36
09636-018
-120 -90.0
09636-017
60 60
09636-016
0 -100
AD9643
0 100 95 SFDR (dBc) -40 IMD3 (dBc) -60 SNR/SFDR (dBc AND dBFS)
-20
SFDR/IMD3 (dBc AND dBFS)
90
85 SFDR, CHANNEL B SNR, CHANNEL B SFDR, CHANNEL A SNR, CHANNEL A
-80 SFDR (dBFS) -100 IMD3 (dBFS)
09636-019
80
75
-78.5
-67.0 -55.5 -44.0 -32.5 INPUT AMPLITUDE (dBFS)
-21.0
-7.0
50
60
70
80 90 100 110 120 130 140 150 160 170 SAMPLE RATE (MSPS)
Figure 12. AD9643-170 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184.12, fIN2 = 187.12 MHz, fS = 170 MSPS
Figure 15. AD9643-170 Single-Tone SNR/SFDR vs. Sample Rate (fS) with fIN = 90.1 MHz
0 -20 -40
AMPLITUDE (dBFS)
6000
170MSPS 89.12MHz @ -7dBFS 92.12MHz @ -7dBFS SFDR = 89dBc (96dBFS)
NUMBER OF HITS
1.34LSB rms 16,379 TOTAL HITS 5000
4000
-60 -80 -100 -120 -140
3000
2000
1000
09636-020
0
10
20
30 40 50 60 FREQUENCY (MHz)
70
80
N-5 N-4N-3N-2N-1 N N+1N+2N+3N+4N+5 OUTPUT CODE
Figure 13. AD9643-170 Two-Tone FFT with fIN1 = 89.12, fIN2 = 92.12 MHz, fS = 170 MSPS
Figure 16. AD9643-170 Grounded Input Histogram
0 -20 -40
AMPLITUDE (dBFS)
0
170MSPS 184.12MHz @ -7dBFS 187.12MHz @ -7dBFS SFDR = 84dBc (91dBFS)
AMPLITUDE (dBFS)
-20 -40 -60 -80 -100 -120 -140
210MSPS 90.1MHz @ -1dBFS SNR = 70.6dB (71.6dBFS) SFDR = 88dBc
-60 -80 -100 -120 -140
SECOND HARMONIC THIRD HARMONIC
09636-021
0
10
20
30 40 50 FREQUENCY (MHz)
60
70
80
0
10
20
30
40 50 60 70 FREQUENCY (Hz)
80
90
100
Figure 14. AD9643-170 Two-Tone FFT with fIN1 = 184.12, fIN2 = 187.12 MHz, fS = 170 MSPS
Figure 17. AD9643-210 Single-Tone FFT with fIN = 90.1 MHz
Rev. A | Page 17 of 36
09636-024
09636-023
0
09636-022
-120 -90.0
70 40
AD9643
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 210MSPS 185.1MHz @ -1dBFS SNR = 70.3dB (71.3dBFS) SFDR = 86dBc
100 95 SFDR (dBc)
SNR/SFDR (dBc AND dBFS)
90 85 80 75 SNR (dBFS) 70 65
SECOND HARMONIC THIRD HARMONIC
09636-025
0
10
20
30
40 50 60 70 FREQUENCY (MHz)
80
90
100
90
120 150
180 210 240 270 300 FREQUENCY (MHz)
330 360 390
Figure 18. AD9643-210 Single-Tone FFT with fIN = 185.1 MHz
Figure 21. AD9643-210 Single-Tone SNR/SFDR vs. Input Frequency (fIN)
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 THIRD HARMONIC SECOND HARMONIC 210MSPS 305.1MHz @ -1dBFS SNR = 67.3dB (68.3dBFS) SFDR = 75dBc
0
-20
SFDR/IMD3 (dBc AND dBFS)
SFDR (dBc) -40 IMD3 (dBc) -60
-80 SFDR (dBFS) -100 IMD3 (dBFS)
0
10
20
30
40 50 60 70 FREQUENCY (MHz)
80
90
100
-78.5
-67.0 -55.5 -44.0 -32.5 INPUT AMPLITUDE (dBFS)
-21.0
-7.0
Figure 19. AD9643-210 Single-Tone FFT with fIN = 305.1 MHz
Figure 22. AD9643-210 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 89.12, fIN2 = 92.12 MHz, fS = 210 MSPS
0
120 SFDR (dBFS) 100
SFDR/IMD3 (dBc AND dBFS)
-20 SFDR (dBc) -40 IMD3 (dBc) -60
SNR/SFDR (dBc AND dBFS)
80
SNR (dBFS)
60 SFDR (dBc) 40 SNR (dBc) 20
-80 SFDR (dBFS) -100 IMD3 (dBFS) -78.5 -67.0 -55.5 -44.0 -32.5 INPUT AMPLITUDE (dBFS) -21.0 -7.0
09636-030
-90
-80
-70 -60 -50 -40 -30 INPUT AMPLITUDE (dBFS)
-20
-10
0
09636-027
0 -100
-120 -90.0
Figure 20. AD9643-210 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 90.1 MHz
Figure 23. AD9643-210 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184.12, fIN2 = 187.12 MHz, fS = 210 MSPS
Rev. A | Page 18 of 36
09636-029
09636-026
-120 -90.0
09636-028
60 60
AD9643
0 -20 -40 210MSPS 89.12MHz @ -7dBFS 92.12MHz @ -7dBFS SFDR = 88dBc (95dBFS)
5000 4500 4000 3500 NUMBER OF HITS 3000 2500 2000 1500 1000 1.44LSB rms 16,378 TOTAL HITS
AMPLITUDE (dBFS)
-60 -80 -100 -120
500
0 10 20 30 40 50 60 70 FREQUENCY (MHz) 80 90 100
N-5 N-4N-3N-2N-1 N N+1N+2N+3N+4N+5 OUTPUT CODE
Figure 24. AD9643-210 Two-Tone FFT with fIN1 = 89.12, fIN2 = 92.12 MHz, fS = 210 MSPS
Figure 27. AD9643-210 Grounded Input Histogram
0 -20 -40 210MSPS 184.12MHz @ -7dBFS 187.12MHz @ -7dBFS SFDR = 88dBc (95dBFS)
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 250MSPS 90.1MHz @ -1dBFS SNR = 70.6dB (71.6dBFS) SFDR = 88dBc
AMPLITUDE (dBFS)
-60 -80 -100 -120 -140
THIRD HARMONIC SECOND HARMONIC
09636-032
0
10
20
30
40 50 60 70 FREQUENCY (MHz)
80
90
100
0
10
20
30
40
50 60 70 80 FREQUENCY (MHz)
90
100 110 120
Figure 25. AD9643-210 Two-Tone FFT with fIN1 = 184.12, fIN2 = 187.12 MHz, fS = 210 MSPS
100
Figure 28. AD9643-250 Single-Tone FFT with fIN = 90.1 MHz
0 -20 -40 250MSPS 185.1MHz @ -1dBFS SNR = 70.6dB (71.6dBFS) SFDR = 85dBc
95
SNR/SFDR (dBc AND dBFS)
90
AMPLITUDE (dBFS)
-60 -80 -100 -120 -140
85 SNR, CHANNEL B SFDR, CHANNEL B SNR, CHANNEL A SFDR, CHANNEL A
THIRD HARMONIC SECOND HARMONIC
80
75
09636-033
60
80
100 120 140 160 SAMPLE RATE (MSPS)
180
200
0
10
20
30
40
50 60 70 80 FREQUENCY (MHz)
90 100 110 120
Figure 26. AD9643-210 Single-Tone SNR/SFDR vs. Sample Rate (fS) with fIN = 90.1 MHz
Figure 29. AD9643-250 Single-Tone FFT with fIN = 185.1 MHz
Rev. A | Page 19 of 36
09636-036
70 40
09636-035
09636-034
09636-031
-140
0
AD9643
0 -20 -40 AMPLITUDE (dBFS) -60 -80 -100 -120 -140 250MSPS 305.1MHz @ -1dBFS SNR = 68.6dB (71.6dBFS) SFDR = 83dBc
0
-20
SFDR/IMD3 (dBc AND dBFS)
SFDR (dBc) -40 IMD3 (dBc) -60
SECOND HARMONIC THIRD HARMONIC
-80 SFDR (dBFS) -100 IMD3 (dBFS)
09636-037
0
10
20
30
40
50 60 70 80 FREQUENCY (MHz)
90 100 110 120
-78.5
-67.0 -55.5 -44.0 -32.5 INPUT AMPLITUDE (dBFS)
-21.0
-7.0
Figure 30. AD9643-250 Single-Tone FFT with fIN = 305.1 MHz
Figure 33. AD9643-250 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 89.12, fIN2 = 92.12 MHz, fS = 250 MSPS
120 SFDR (dBFS) 100
SFDR/IMD3 (dBc AND dBFS)
0
-20 SFDR (dBc) -40 IMD3 (dBc) -60
SNR/SFDR (dBc AND dBFS)
80
SNR (dBFS)
60 SFDR (dBc) 40 SNR (dBc)
-80 SFDR (dBFS) -100 IMD3 (dBFS)
20
09636-038
-90
-80
-70 -60 -50 -40 -30 INPUT AMPLITUDE (dBFS)
-20
-10
0
-78.5
-67.0 -55.5 -44.0 -32.5 INPUT AMPLITUDE (dBFS)
-21.0
-7.0
Figure 31. AD9643-250 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 185.1 MHz
Figure 34. AD9643-250 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 184.12, fIN2 = 187.12 MHz, fS = 250 MSPS
100 95
SNR/SFDR (dBc AND dBFS)
0 -20 250MSPS 89.12MHz @ -7dBFS 92.12MHz @ -7dBFS SFDR = 87dBc (94dBFS)
90 85 80 75
SFDR (dBc)
-40
AMPLITUDE (dBFS)
-60 -80 -100 -120 -140
SNR (dBFS) 70 65
09636-039
80
100
120
140 160 180 200 FREQUENCY (MHz)
220
240
260
0
10
20
30
40
50 60 70 80 FREQUENCY (MHz)
90 100 110 120
Figure 32. AD9643-250 Single-Tone SNR/SFDR vs. Input Frequency (fIN)
Figure 35. AD9643-250 Two-Tone FFT with fIN1 = 89.12, fIN2 = 92.12 MHz, fS = 250 MSPS
Rev. A | Page 20 of 36
09636-042
60 60
09636-041
0 -100
-120 -90.0
09636-040
-120 -90.0
AD9643
0 -20 -40 250MSPS 184.12MHz @ -7dBFS 187.12MHz @ -7dBFS SFDR = 87dBc (94dBFS)
5000 4500 4000 3500 NUMBER OF HITS 3000 2500 2000 1500 1000 1.33LSB rms 16,378 TOTAL HITS
AMPLITUDE (dBFS)
-60 -80 -100 -120
500
0 10 20 30 40 50 60 70 80 FREQUENCY (MHz) 90 100 110 120
N-5 N-4N-3N-2N-1 N N+1N+2N+3N+4N+5 OUTPUT CODE
Figure 36. AD9643-250 Two-Tone FFT with fIN1 = 184.12, fIN2 = 187.12 MHz, fS = 250 MSPS
Figure 38. AD9643-250 Grounded Input Histogram
100
95
SNR/SFDR (dBc AND dBFS)
90
85 SNR, CHANNEL B SFDR, CHANNEL B SNR, CHANNEL A SFDR, CHANNEL A
80
75
60
80
100
120 140 160 180 SAMPLE RATE (MSPS)
200
220
240
Figure 37. AD9643-250 Single-Tone SNR/SFDR vs. Sample Rate (fS) with fIN = 90.1 MHz
09636-044
70 40
Rev. A | Page 21 of 36
09636-045
09636-043
-140
0
AD9643 EQUIVALENT CIRCUITS
AVDD
SCLK OR PDWN 350 26k
VIN
09636-006
Figure 39. Equivalent Analog Input Circuit
Figure 43. Equivalent SCLK or PDWN Input Circuit
AVDD
AVDD
AVDD 0.9V CLK+ 15k 15k
AVDD
CSB OR OEB
26k
350
CLK-
09636-007
Figure 40. Equivalent Clock lnput Circuit
Figure 44. Equivalent CSB Input Circuit
DRVDD
AVDD
AVDD
V+ DATAOUT- V-
V- DATAOUT+ V+
SYNC 16k
09636-063
0.9V
0.9V
Figure 41. Equivalent LVDS Output Circuit
Figure 45. Equivalent SYNC Input Circuit
DRVDD
SDIO
350
Figure 42. Equivalent SDIO Circuit
09636-009
26k
Rev. A | Page 22 of 36
09636-012
09636-011
09636-010
AD9643 THEORY OF OPERATION
The AD9643 has two analog input channels and two digital output channels. The intermediate frequency (IF) signal passes through several stages before appearing at the output port(s). The dual ADC design can be used for diversity reception of signals, where the ADCs operate identically on the same carrier but from two separate antennae. The ADCs can also be operated with independent analog inputs. The user can sample frequencies from dc to 300 MHz using appropriate low-pass or band-pass filtering at the ADC inputs with little loss in ADC performance. Operation to 400 MHz analog input is permitted but occurs at the expense of increased ADC noise and distortion. Synchronization capability is provided to allow synchronized timing between multiple devices. Programming and control of the AD9643 are accomplished using a 3-pin, SPI-compatible serial interface. A small resistor in series with each input can help reduce the peak transient current required from the output stage of the driving source. A shunt capacitor can be placed across the inputs to provide dynamic charging currents. This passive network creates a low-pass filter at the ADC input; therefore, the precise values are dependent on the application. In intermediate frequency (IF) undersampling applications, the shunt capacitors should be reduced. In combination with the driving source impedance, the shunt capacitors limit the input bandwidth. Refer to the AN-742 Application Note, Frequency Domain Response of Switched-Capacitor ADCs; the AN-827 Application Note, A Resonant Approach to Interfacing Amplifiers to Switched-Capacitor ADCs; and the Analog Dialogue article, "Transformer-Coupled Front-End for Wideband A/D Converters," for more information on this subject.
BIAS S CS VIN+ CPAR1 CPAR2 H CS VIN- S
09636-050
ADC ARCHITECTURE
The AD9643 architecture consists of a dual front-end sampleand-hold circuit, followed by a pipelined switched-capacitor ADC. The quantized outputs from each stage are combined into a final 14-bit result in the digital correction logic. The pipelined architecture permits the first stage to operate on a new input sample and the remaining stages to operate on the preceding samples. Sampling occurs on the rising edge of the clock. Each stage of the pipeline, excluding the last, consists of a low resolution flash ADC connected to a switched-capacitor digitalto-analog converter (DAC) and an interstage residue amplifier (MDAC). The MDAC magnifies the difference between the reconstructed DAC output and the flash input for the next stage in the pipeline. One bit of redundancy is used in each stage to facilitate digital correction of flash errors. The last stage simply consists of a flash ADC. The input stage of each channel contains a differential sampling circuit that can be ac- or dc-coupled in differential or singleended modes. The output staging block aligns the data, corrects errors, and passes the data to the output buffers. The output buffers are powered from a separate supply, allowing digital output noise to be separated from the analog core. During power-down, the output buffers go into a high impedance state.
S CFB
S
S
CPAR1
CPAR2 BIAS
S
CFB
Figure 46. Switched-Capacitor Input
For best dynamic performance, the source impedances driving VIN+ and VIN- should be matched, and the inputs should be differentially balanced.
Input Common Mode
The analog inputs of the AD9643 are not internally dc biased. In ac-coupled applications, the user must provide this bias externally. Setting the device so that VCM = 0.5 x AVDD (or 0.9 V) is recommended for optimum performance. An on-board common-mode voltage reference is included in the design and is available from the VCM pin. Using the VCM output to set the input common mode is recommended. Optimum performance is achieved when the common-mode voltage of the analog input is set by the VCM pin voltage (typically 0.5 x AVDD). The VCM pin must be decoupled to ground by a 0.1 F capacitor, as described in the Applications Information section. This decoupling capacitor should be placed close to the pin to minimize the series resistance and inductance between the part and this capacitor.
ANALOG INPUT CONSIDERATIONS
The analog input to the AD9643 is a differential switchedcapacitor circuit that has been designed for optimum performance while processing a differential input signal. The clock signal alternatively switches the input between sample mode and hold mode (see the configuration shown in Figure 46). When the input is switched into sample mode, the signal source must be capable of charging the sampling capacitors and settling within 1/2 clock cycle.
Differential Input Configurations
Optimum performance is achieved while driving the AD9643 in a differential input configuration. For baseband applications, the AD8138, ADA4937-2, ADA4938-2, and ADA4930-2
Rev. A | Page 23 of 36
AD9643
differential drivers provide excellent performance and a flexible interface to the ADC. The output common-mode voltage of the ADA4930-2 is easily set with the VCM pin of the AD9643 (see Figure 47), and the driver can be configured in a Sallen-Key filter topology to provide band-limiting of the input signal.
15pF 200 VIN 76.8 90 33 5pF 15 VIN- AVDD ADC 15 VIN+ VCM
the recommended input configuration (see Figure 50). In this configuration, the input is ac-coupled and the VCM voltage is provided to each input through a 33 resistor. These resistors compensate for losses in the input baluns to provide a 50 impedance to the driver. In the double balun and transformer configurations, the value of the input capacitors and resistors is dependent on the input frequency and source impedance. Based on these parameters, the value of the input resistors and capacitors may need to be adjusted or some components may need to be removed. Table 10 displays recommended values to set the RC network for different input frequency ranges. However, these values are dependent on the input signal and bandwidth and should be used only as a starting guide. Note that the values given in Table 10 are for each R1, R2, C2, and R3 component shown in Figure 48 and Figure 50. Table 10. Example RC Network
Frequency Range (MHz) 0 to 100 100 to 300 R1 Series () 33 15 C1 Differential (pF) 8.2 3.9 R2 Series () 0 0 C2 Shunt (pF) 15 8.2 R3 Shunt () 49.9 49.9
ADA4930-2
0.1F 120 200 33 15pF 33
0.1F
Figure 47. Differential Input Configuration Using the ADA4930-2
For baseband applications where SNR is a key parameter, differential transformer coupling is the recommended input configuration. An example is shown in Figure 48. To bias the analog input, the VCM voltage can be connected to the center tap of the secondary winding of the transformer.
C2 R3 R1 2V p-p 49.9 C1 R1 R2 VIN- ADC VCM R2 VIN+
09636-051
An alternative to using a transformer-coupled input at frequencies in the second Nyquist zone is to use an amplifier with variable gain. The AD8375 or AD8376 digital variable gain amplifier (DVGAs) provides good performance for driving the AD9643. Figure 49 shows an example of the AD8376 driving the AD9643 through a band-pass antialiasing filter.
1000pF 180nH 220nH
09636-052
0.1F C2
R3
33
0.1F
1H VPOS
165 5.1pF 1nF 301 3.9pF 165
15pF VCM 1nF 68nH
AD8376
1H
AD9643
2.5k2pF
Figure 48. Differential Transformer-Coupled Configuration
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 AD9643. For applications where SNR is a key parameter, differential double balun coupling is
Figure 49. Differential Input Configuration Using the AD8376
C2 0.1F 2V p-p PA S S P 0.1F 33 0.1F 33 0.1F C1 R1 R2 VIN- 33 ADC VCM R3 R1 R2
VIN+
R3 C2
Figure 50. Differential Double Balun Input Configuration
Rev. A | Page 24 of 36
09636-053
0.1F
09636-054
The signal characteristics must be considered when selecting a transformer. Most RF transformers saturate at frequencies below a few megahertz. Excessive signal power can also cause core saturation, which leads to distortion.
1000pF 180nH 220nH NOTES 1. ALL INDUCTORS ARE COILCRAFT(R) 0603CS COMPONENTS WITH THE EXCEPTION OF THE 1H CHOKE INDUCTORS (COIL CRAFT 0603LS). 2. FILTER VALUES SHOWN ARE FOR A 20MHz BANDWIDTH FILTER CENTERED AT 140MHz.
AD9643
VOLTAGE REFERENCE
A stable and accurate voltage reference is built into the AD9643. The full-scale input range can be adjusted by varying the reference voltage via SPI. The input span of the ADC tracks reference voltage changes linearly.
CLOCK INPUT 390pF 25 390pF
ADC
CLK+
390pF 1nF 25 SCHOTTKY DIODES: HSMS2822 CLK-
09636-057
CLOCK INPUT CONSIDERATIONS
For optimum performance, the AD9643 sample clock inputs, CLK+ and CLK-, should be clocked with a differential signal. The signal is typically ac-coupled into the CLK+ and CLK- pins via a transformer or via capacitors. These pins are biased internally (see Figure 51) and require no external bias. If the inputs are floated, the CLK- pin is pulled low to prevent spurious clocking.
AVDD
Figure 53. Balun-Coupled Differential Clock (Up to 625 MHz)
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 54. The AD9510, AD9511, AD9512, AD9513, AD9514, AD9515, AD9516, AD9517, AD9518, AD9520, AD9522, AD9523, AD9524, and ADCLK905/ADCLK907/ ADCLK925 clock drivers offer excellent jitter performance.
0.1F 0.1F
0.9V
ADC
CLK+ 100
CLK+ 4pF 4pF
CLK-
CLOCK INPUT
AD95xx
09636-055
50k
50k
240
240
Figure 51. Simplified Equivalent Clock Input Circuit
Figure 54. Differential PECL Sample Clock (Up to 625 MHz)
Clock Input Options
The AD9643 has a very flexible clock input structure. Clock input can be a CMOS, LVDS, LVPECL, or sine wave signal. Regardless of the type of signal being used, clock source jitter is of the most concern, as described in the Jitter Considerations section. Figure 52 and Figure 53 show two preferable methods for clocking the AD9643 (at clock rates of up to 625 MHz). A low jitter clock source is converted from a single-ended signal to a differential signal using an RF balun or RF transformer. 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. The back-to-back Schottky diodes across the transformer secondary limit clock excursions into the AD9643 to approximately 0.8 V p-p differential. This limit helps prevent the large voltage swings of the clock from feeding through to other portions of the AD9643 while preserving the fast rise and fall times of the signal, which are critical to low jitter performance.
Mini-Circuits(R) ADT1-1WT, 1:1Z 390pF XFMR 100 390pF CLK-
09636-056
A third option is to ac-couple a differential LVDS signal to the sample clock input pins, as shown in Figure 55. The AD9510, AD9511, AD9512, AD9513, AD9514, AD9515, AD9516, AD9517, AD9518, AD9520, AD9522, AD9523, and AD9524 clock drivers offer excellent jitter performance.
0.1F CLOCK INPUT 0.1F
ADC
CLK+
AD95xx
0.1F CLOCK INPUT 50k 50k LVDS DRIVER
100 0.1F CLK-
09636-059
Figure 55. Differential LVDS Sample Clock (Up to 625 MHz)
Input Clock Divider
The AD9643 contains an input clock divider with the ability to divide the input clock by integer values between 1 and 8. The duty cycle stabilizer (DCS) is enabled by default on power-up. The AD9643 clock divider can be synchronized using the external SYNC input. Bit 1 and Bit 2 of Register 0x3A allow the clock divider to be resynchronized on every SYNC signal or only on the first SYNC signal after the register is written. A valid SYNC causes the clock divider to reset to its initial state. This synchronization feature allows multiple parts to have their clock dividers aligned to guarantee simultaneous input sampling.
CLOCK INPUT
390pF 50
ADC
CLK+
SCHOTTKY DIODES: HSMS2822
Figure 52. Transformer-Coupled Differential Clock (Up to 200 MHz)
Rev. A | Page 25 of 36
09636-058
CLOCK INPUT
0.1F
PECL DRIVER
0.1F CLK-
AD9643
Clock Duty Cycle
Typical high speed ADCs use both clock edges to generate a variety of internal timing signals and, as a result, may be sensitive to clock duty cycle. Commonly, a 5% tolerance is required on the clock duty cycle to maintain dynamic performance characteristics. The AD9643 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 AD9643. Jitter on the rising edge of the input clock is still of paramount concern and is not reduced by the duty cycle stabilizer. The duty cycle control loop does not function for clock rates less than 40 MHz nominally. The loop has a time constant associated with it that must be considered when the clock rate can change dynamically. A wait time of 1.5 s to 5 s is required after a dynamic clock frequency increase or decrease before the DCS loop is relocked to the input signal. During the time period that the loop is not locked, the DCS loop is bypassed, and internal device timing is dependent on the duty cycle of the input clock signal. In such applications, it may be appropriate to disable the duty cycle stabilizer. In all other applications, enabling the DCS circuit is recommended to maximize ac performance. Power supplies for clock drivers should be separated from the ADC output driver supplies to avoid modulating the clock signal with digital noise. Low jitter, crystal controlled oscillators make the best clock sources. If the clock is generated from another type of source (by gating, dividing, or another method), it should be retimed by the original clock at the last step. Refer to the AN-501 Application Note, Aperture Uncertainty and ADC System Performance, and the AN-756 Application Note, Sampled Systems and the Effects of Clock Phase Noise and Jitter, for more information about jitter performance as it relates to ADCs.
POWER DISSIPATION AND STANDBY MODE
As shown in Figure 57, the power dissipated by the AD9643 is proportional to its sample rate. The data in Figure 57 was taken using the same operating conditions as those used for the Typical Performance Characteristics section.
0.8 0.7 0.6 0.5 0.4 0.3 IDRVDD 0.2 0.1
09636-061
0.5 TOTAL POWER 0.4
SUPPLY CURRENT (A)
TOTAL POWER (W)
0.3 IAVDD 0.2
Jitter Considerations
High speed, high resolution ADCs are sensitive to the quality of the clock input. The degradation in SNR at a given input frequency (fIN) due to jitter (tJ) can be calculated by SNRHF = -10 log[(2 x fIN x tJRMS)2 + 10 ( - SNR LF /10 ) ] In the equation, the rms aperture jitter represents the rootmean-square of all jitter sources, which include the clock input, the analog input signal, and the ADC aperture jitter specification. IF undersampling applications are particularly sensitive to jitter, as shown in Figure 56.
80
0.1
0 40
0 60 80 100 120 140 160 180 200 ENCODE FREQUENCY (MSPS) 220 240
Figure 57. AD9643-250 Power and Current vs. Sample Rate
75
By asserting PDWN (either through the SPI port or by asserting the PDWN pin high), the AD9643 is placed in power-down mode. In this state, the ADC typically dissipates 10 mW. During power-down, the output drivers are placed in a high impedance state. Asserting the PDWN pin low returns the AD9643 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-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.
70
SNR (dBc)
65
60
55
0.05ps 0.2ps 0.5ps 1ps 1.5ps MEASURED 1 10 100 INPUT FREQUENCY (MHz) 1000
09636-060
50
Figure 56. AD9643-250 SNR vs. Input Frequency and Jitter
The clock input should be treated as an analog signal in cases where aperture jitter may affect the dynamic range of the AD9643.
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 Register Description section and the AN-877 Application Note, Interfacing to High Speed ADCs via SPI, for additional details.
Rev. A | Page 26 of 36
AD9643
DIGITAL OUTPUTS
The AD9643 output drivers can be configured for either ANSI LVDS or reduced drive LVDS using a 1.8 V DRVDD supply. 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. bar bit (Bit 4) in Register 0x14. Because the output data is interleaved, if only one of the two channels is disabled, the output data of the remaining channel is repeated in both the rising and falling output clock cycles.
Timing
The AD9643 provides latched data with a pipeline delay of 10 input sample clock cycles. Data outputs are available one propagation delay (tPD) after the rising edge of the clock signal. The length of the output data lines and loads placed on them should be minimized to reduce transients within the AD9643. These transients can degrade converter dynamic performance. The lowest typical conversion rate of the AD9643 is 40 MSPS. At clock rates below 40 MSPS, dynamic performance may degrade.
Digital Output Enable Function (OEB)
The AD9643 has a flexible three-state ability for the digital output pins. The three-state mode is enabled using the OEB pin or through the SPI interface. If the OEB pin is low, the output data drivers are enabled. If the OEB pin is high, the output data drivers are placed in a high impedance state. This OEB function is not intended for rapid access to the data bus. Note that OEB is referenced to the digital output driver supply (DRVDD) and should not exceed that supply voltage. When using the SPI interface, the data outputs of each channel can be independently three-stated by using the output enable Table 11. Output Data Format
Input (V) VIN+ - VIN- VIN+ - VIN- VIN+ - VIN- VIN+ - VIN- VIN+ - VIN- VIN+ - VIN-, Input Span = 1.75 V p-p (V) <-0.875 -0.875 0 +0.875 >+0.875
Data Clock Output (DCO)
The AD9643 also provides data clock output (DCO) intended for capturing the data in an external register. Figure 2 shows a graphical timing diagram of the AD9643 output modes.
Offset Binary Output Mode 00 0000 0000 0000 00 0000 0000 0000 10 0000 0000 0000 11 1111 1111 1111 11 1111 1111 1111
Twos Complement Mode (Default) 10 0000 0000 0000 10 0000 0000 0000 00 0000 0000 0000 01 1111 1111 1111 01 1111 1111 1111
OR 1 0 0 0 1
Rev. A | Page 27 of 36
AD9643 CHANNEL/CHIP SYNCHRONIZATION
The AD9643 has a SYNC input that allows the user flexible synchronization options for synchronizing the internal blocks. The SYNC feature is useful for guaranteeing synchronized operation across multiple ADCs. The input clock divider can be synchronized using the SYNC input. The divider can be enabled to synchronize on a single occurrence of the SYNC signal or on every occurrence by setting the appropriate bits in Register 0x3A. The SYNC input is internally synchronized to the sample clock. However, to ensure that there is no timing uncertainty between multiple parts, the SYNC input signal should be synchronized to the input clock signal. The SYNC input should be driven using a single-ended CMOS type signal. Using Bit 1 in Register 0x59, the SYNC input can be set to either level or edge sensitive mode. If the SYNC input is set to edge sensitive mode, Bit 0 of Register 0x59 can be used to determine whether the rising or falling edge is used.
Rev. A | Page 28 of 36
AD9643 SERIAL PORT INTERFACE (SPI)
The AD9643 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. These fields are documented in the Memory Map section. For detailed operational information, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. All data is composed of 8-bit words. The first bit of each individual byte of serial data indicates whether a read or write command is issued. This allows the serial data input/output (SDIO) pin to change direction from an input to an output. In addition to word length, the instruction phase determines whether the serial frame is a read or write operation, allowing the serial port to be used both to program the chip and to read the contents of the on-chip memory. If the instruction is a readback operation, performing a readback causes the serial data input/ output (SDIO) pin to change direction from an input to an output at the appropriate point in the serial frame. Data can be sent in MSB first mode or in LSB first mode. MSB first is the default on power-up and can be changed via the SPI port configuration register. For more information about this and other features, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI.
CONFIGURATION USING THE SPI
Three pins define the SPI of this ADC: the SCLK pin, the SDIO pin, and the CSB pin (see Table 12). The SCLK (serial clock) pin is used to synchronize the read and write data presented from/to the ADC. The SDIO (serial data input/output) pin is a dual-purpose pin that allows data to be sent and read from the internal ADC memory map registers. The CSB (chip select bar) pin is an active low control that enables or disables the read and write cycles. Table 12. Serial Port Interface Pins
Pin SCLK SDIO 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.
HARDWARE INTERFACE
The pins described in Table 12 comprise the physical interface between the user programming device and the serial port of the AD9643. 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 AD9643 to prevent these signals from transitioning at the converter inputs during critical sampling periods.
CSB
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 58 and Table 5. Other modes involving the CSB are available. The CSB can be held low indefinitely, which permanently enables the device; this is called streaming. The CSB can stall high between bytes to allow for additional external timing. When CSB is tied high, SPI functions are placed in a high impedance mode. This mode turns on any SPI pin secondary functions. During an instruction phase, a 16-bit instruction is transmitted. Data follows the instruction phase, and its length is determined by the W0 and the W1 bits.
Rev. A | Page 29 of 36
AD9643
SPI ACCESSIBLE FEATURES
Table 13 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 AD9643 part-specific features are described in the Memory Map Register Description section.
Table 13. Features Accessible Using the SPI
Feature Name Mode Clock Offset Test I/O Output Mode Output Phase Output Delay VREF 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 Allows the user to set the reference voltage
tDS tS
CSB
tHIGH tDH tLOW
tCLK
tH
SCLK DON'T CARE
DON'T CARE
SDIO DON'T CARE
R/W
W1
W0
A12
A11
A10
A9
A8
A7
D5
D4
D3
D2
D1
D0
DON'T CARE
Figure 58. Serial Port Interface Timing Diagram
Rev. A | Page 30 of 36
09636-062
AD9643 MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Each row in the memory map register table has eight bit locations. The memory map is roughly divided into three sections: the chip configuration registers (Address 0x00 to Address 0x02); the channel index and transfer registers (Address 0x05 and Address 0xFF); and the ADC functions registers, including setup, control, and test (Address 0x08 to Address 0x59). The memory map register table (see Table 14) 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 0x14, the output mode register, has a hexadecimal default value of 0x05. This means that Bit 0 = 1 and Bit 2 = 1, and the remaining bits are 0s. This setting is the default output format value, which is twos complement. For more information on this function and others, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI. This document details the functions controlled by Register 0x00 to Register 0x25. The remaining registers, Register 0x3A and Register 0x59, are documented in the Memory Map Register Description section.
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 0x20, Address 0x3A, and Address 0x59 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.
Channel-Specific Registers
Some channel setup functions, such as the signal monitor thresholds, can be programmed to a different value for each channel. In these cases, channel address locations are internally duplicated for each channel. These registers and bits are designated in Table 14 as local. These local registers and bits can be accessed by setting the appropriate Channel A or Channel B bits in Register 0x05. If both bits are set, the subsequent write affects the registers of both channels. In a read cycle, only Channel A or Channel B should be set to read one of the two registers. If both bits are set during an SPI read cycle, the part returns the value for Channel A. Registers and bits designated as global in Table 14 affect the entire part and the channel features for which independent settings are not allowed between channels. The settings in Register 0x05 do not affect the global registers and bits.
Open and Reserved Locations
All address and bit locations that are not included in Table 14 are not currently supported for this device. Unused bits of a valid address location should be written with 0s. Writing to these locations is required only when part of an address location is open (for example, Address 0x18). If the entire address location is open (for example, Address 0x13), this address location should not be written.
Default Values
After the AD9643 is reset, critical registers are loaded with default values. The default values for the registers are given in the memory map register table, Table 14.
Rev. A | Page 31 of 36
AD9643
MEMORY MAP REGISTER TABLE
All address and bit locations that are not included in Table 14 are not currently supported for this device. Table 14. Memory Map Registers
Addr Register Bit 7 (Hex) Name (MSB) Chip Configuration Registers 0x00 0 SPI port configuration (global) 1 Bit 6 LSB first Bit 5 Soft reset Bit 4 1 Bit 3 1 Bit 2 Soft reset Bit 1 LSB first Bit 0 (LSB) 0 Default Value (Hex) 0x18 Default Notes/ Comments The nibbles are mirrored so that LSB first mode or MSB first mode registers correctly, regardless of shift mode. Read only.
0x01
Chip ID (global) Chip grade (global) Open Open
0x02
8-bit chip ID[7:0] (AD9643 = 0x82) (default) Open Speed grade ID 00 = 250 MSPS
0x82
Open
Open
Open
Speed grade ID used to differentiate devices; read only. 0x03 Bits are set to determine which device on the chip receives the next write command; applies to local registers only. Synchronously transfers data from the master shift register to the slave. Determines various generic modes of chip operation.
Channel Index and Transfer Registers 0x05 Channel index Open (global)
Open
Open
Open
Open
Open
ADC B (default)
ADC A (default)
0xFF
Transfer (global)
Open
Open
Open
Open
Open
Open
Open
Transfer
0x00
ADC Functions 0x08 Power modes (local)
Open
Open
0x09
Global clock (global) Clock divide (global)
Open
Open
External powerdown pin function (local) 0 = powerdown 1 = standby Open
Open
Open
Open
Internal power-down mode (local) 00 = normal operation 01 = full power-down 10 = standby 11 = reserved
0x00
Open
Open
Open
Open
Duty cycle stabilizer (default)
0x01
0x0B
Open
Open
Input clock divider phase adjust 000 = no delay 001 = 1 input clock cycle 010 = 2 input clock cycles 011 = 3 input clock cycles 100 = 4 input clock cycles 101 = 5 input clock cycles 110 = 6 input clock cycles 111 = 7 input clock cycles
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
0x00
Clock divide values other than 000 automatically cause the duty cycle stabilizer to become active.
Rev. A | Page 32 of 36
AD9643
Addr (Hex) 0x0D Register Name Test mode (local) Bit 7 (MSB) User test mode control 0 = continuous/ repeat pattern 1 = single pattern, then 0s Bit 6 Open Bit 5 Reset PN long gen Bit 2 Bit 1 Output test mode 0000 = off (default) 0001 = midscale short 0010 = positive FS 0011 = negative FS 0100 = alternating checkerboard 0101 = PN long sequence 0110 = PN short sequence 0111 = one/zero word toggle 1000 = user test mode 1001 to 1110 = unused 1111 = ramp output Open Open Open BIST enable Reset BIST sequence Offset adjust in LSBs from +31 to -32 (twos complement format) Open Output format Output Output enable bar invert (local) 00 = offset binary (local) 1 = normal 01 = twos complement (default) (default) 0 = inverted 10 = gray code 11 = reserved (local) Open LVDS output drive current adjust 0000 = 3.72 mA output drive current 0001 = 3.5 mA output drive current (default) 0010 = 3.30 mA output drive current 0011 = 2.96 mA output drive current 0100 = 2.82 mA output drive current 0101 = 2.57 mA output drive current 0110 = 2.27 mA output drive current 0111 = 2.0 mA output drive current (reduced range) 1000 to 1111 = reserved Open Open Open Open Open Bit 4 Reset PN short gen Bit 3 Bit 0 (LSB) Default Value (Hex) 0x00 Default Notes/ Comments When this register is set, the test data is placed on the output pins in place of normal data.
0x0E 0x10 0x14
BIST enable (local) Offset adjust (local) Output mode
Open Open Open
Open Open Open
Open
0x00 0x00 0x05 Configures the outputs and the format of the data.
Open
0x15
Output Adjust (Global)
Open
Open
Open
0x01
0x16
0x17
Clock phase control (global) DCO output delay (global)
Invert DCO clock Enable DCO clock delay
Open
Open
0x00
Open
Open
0x18
Input Span select (global)
Open
Open
Open
0x19
0x1A
0x1B
0x1C
0x1D
0x1E
User Test Pattern 1 LSB (global) User Test Pattern 1 MSB (global) User Test Pattern 2 LSB (global) User Test Pattern 2 MSB (global) User Test Pattern 3 LSB (global) User Test Pattern 3 MSB (global)
DCO clock delay [delay = (3100 ps x register value/31 +100)] 00000 = 100 ps 00001 = 200 ps 00010 = 300 ps ... 11110 = 3100 ps 11111 = 3200 ps Full-scale input voltage selection 01111 = 2.087 V p-p ... 00001 = 1.772 V p-p 00000 = 1.75 V p-p (default) 11111 = 1.727 V p-p ... 10000 = 1.383 V p-p User Test Pattern 1[7:0]
0x00
0x00
Full-scale input adjustment in 0.022 V steps.
0x00
User Test Pattern 1[15:8]
0x00
User Test Pattern 2[7:0]
0x00
User Test Pattern 2[15:8]
0x00
User Test Pattern 3[7:0]
0x00
User Test Pattern 3[15:8]
0x00
Rev. A | Page 33 of 36
AD9643
Addr (Hex) 0x1F Register Name User Test Pattern 4 LSB (global) User Test Pattern 4 MSB (global) BIST signature LSB (local) BIST signature MSB (local) Sync control (global) Bit 7 (MSB) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 User Test Pattern 4[7:0] Bit 1 Bit 0 (LSB) Default Value (Hex) 0x00 Default Notes/ Comments
0x20
User Test Pattern 4[15:8]
0x00
0x24 0x25 0x3A
BIST signature[7:0] BIST signature[15:8] Open Open Open Open Open Clock divider next sync only Open Clock divider sync enable SYNC pin sensitivity 0 = sync on high level 1 = sync on edge Master sync buffer enable
0x00 0x00 0x00
Read only. Read only.
0x59
SYNC pin control (local)
Open
Open
Open
Open
Open
SYNC pin edge sensitivity 0 = sync on falling edge 1 = sync on rising edge
0x00
1
The channel index register at Address 0x05 should be set to 0x03 (default) when writing to Address 0x00.
MEMORY MAP REGISTER DESCRIPTION
For more information on functions controlled in Register 0x00 to Register 0x25, see the AN-877 Application Note, Interfacing to High Speed ADCs via SPI.
Bit 0--Master Sync Buffer Enable
Bit 0 must be set high to enable any of the sync functions. If the sync capability is not used, this bit should remain low to conserve power.
Sync Control (Register 0x3A) Bits[7:3]--Reserved Bit 2--Clock Divider Next Sync Only
If the master sync buffer enable bit (Address 0x3A, Bit 0) and the clock divider sync enable bit (Address 0x3A, Bit 1) are high, Bit 2 allows the clock divider to sync to the first sync pulse that it receives and to ignore the rest. The clock divider sync enable bit (Address 0x3A, Bit 1) resets after it syncs.
SYNC Pin Control (Register 0x59) Bits [7:2]--Reserved Bit 1--SYNC Pin Sensitivity
If Bit 1 is set to 0, the SYNC input responds to a level. If this bit is set low, the SYNC input responds to the edge (rising or falling) set in Bit 0 of Address 0x59.
Bit 0--SYNC Pin Edge Sensitivity
If Bit 1 is set high, setting Bit 0 to a 0 causes the SYNC input to respond to a falling edge. If this bit is set, the SYNC input respond to a rising edge.
Bit 1--Clock Divider Sync Enable
Bit 1 gates the sync pulse to the clock divider. The sync signal is enabled when Bit 1 is high and Bit 0 is high. This is continuous sync mode.
Rev. A | Page 34 of 36
AD9643 APPLICATIONS INFORMATION
DESIGN GUIDELINES
Before starting system level design and layout of the AD9643, it is recommended that the designer become familiar with these guidelines, which discuss the special circuit connections and layout requirements needed for certain pins.
VCM
The VCM pin should be decoupled to ground with a 0.1 F capacitor, as shown in Figure 48. For optimal channel-to-channel isolation, a 33 resistor should be included between the AD9643 VCM pin and the Channel A analog input network connection, as well as between the AD9643 VCM pin and the Channel B analog input network connection.
Power and Ground Recommendations
When connecting power to the AD9643, it is recommended that two separate 1.8 V supplies be used: one supply should be used for analog (AVDD), and a separate supply should be used for the digital outputs (DRVDD). The designer can employ several different decoupling capacitors to cover both high and low frequencies. These capacitors should be located close to the point of entry at the PC board level and close to the pins of the part with minimal trace length. A single PCB ground plane should be sufficient when using the AD9643. With proper decoupling and smart partitioning of the PCB analog, digital, and clock sections, optimum performance is easily achieved.
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 AD9643 to keep these signals from transitioning at the converter input pins during critical sampling periods.
Exposed Paddle Thermal Heat Slug Recommendations
It is mandatory that the exposed paddle on the underside of the ADC be connected to analog ground (AGND) to achieve the best electrical and thermal performance. A continuous, exposed (no solder mask) copper plane on the PCB should mate to the AD9643 exposed paddle, Pin 0. The copper plane should have several vias to achieve the lowest possible resistive thermal path for heat dissipation to flow through the bottom of the PCB. These vias should be filled or plugged with nonconductive epoxy. To maximize the coverage and adhesion between the ADC and the PCB, a silkscreen should be overlaid to partition the continuous plane on the PCB into several uniform sections. This provides several tie points between the ADC and the PCB during the reflow process. Using one continuous plane with no partitions guarantees only one tie point between the ADC and the PCB. See the evaluation board for a PCB layout example. For detailed information about the packaging and PCB layout of chip scale packages, refer to the AN-772 Application Note, A Design and Manufacturing Guide for the Lead Frame Chip Scale Package (LFCSP).
Rev. A | Page 35 of 36
AD9643 OUTLINE DIMENSIONS
9.00 BSC SQ 0.60 MAX 0.60 MAX
49 48 64 1
PIN 1 INDICATOR
PIN 1 INDICATOR TOP VIEW 8.75 BSC SQ 0.50 BSC EXPOSED PAD
(BOTTOM VIEW)
6.35 6.20 SQ 6.05
0.50 0.40 0.30
33 32
16 17
0.25 MIN 7.50 REF
1.00 0.85 0.80
12 MAX
0.80 MAX 0.65 TYP 0.05 MAX 0.02 NOM 0.30 0.23 0.18 0.20 REF
SEATING PLANE
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-VMMD-4
Figure 59. 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 9 mm x 9 mm Body, Very Thin Quad (CP-64-4) Dimensions shown in millimeters
ORDERING GUIDE
Model1 AD9643BCPZ-170 AD9643BCPZ-210 AD9643BCPZ-250 AD9643BCPZRL7-170 AD9643BCPZRL7-210 AD9643BCPZRL7-250 AD9643-170EBZ AD9643-210EBZ AD9643-250EBZ
1
Temperature Range -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C
Package Description 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 64-Lead Lead Frame Chip Scale Package [LFCSP_VQ] Evaluation Board with AD9643-170 Evaluation Board with AD9643-210 Evaluation Board with AD9643-250
Package Option CP-64-4 CP-64-4 CP-64-4 CP-64-4 CP-64-4 CP-64-4
Z = RoHS Compliant Part.
(c)2011 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D09636-0-5/11(A)
Rev. A | Page 36 of 36
091707-C

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