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14-Bit, 150 MSPS, 1.8 V Analog-to-Digital Converter AD9254
FEATURES
1.8 V analog supply operation 1.8 V to 3.3 V output supply SNR = 71.8 dBc (72.8 dBFS) to 70 MHz input SFDR = 84 dBc to 70 MHz input Low power: 430 mW @ 150 MSPS Differential input with 650 MHz bandwidth On-chip voltage reference and sample-and-hold amplifier DNL = 0.4 LSB Flexible analog input: 1 V p-p to 2 V p-p range Offset binary, Gray code, or twos complement data format Clock duty cycle stabilizer Data output clock Serial port control Built-in selectable digital test pattern generation Programmable clock and data alignment
FUNCTIONAL BLOCK DIAGRAM
AVDD DRVDD
AD9254
VIN+ VIN- SHA MDAC1 4 REFT REFB CORRECTION LOGIC 15 OUTPUT BUFFERS VREF SENSE REF SELECT DCO D13 (MSB) D0 (LSB) 0.5V CLOCK DUTY CYCLE STABILIZER MODE SELECT SCLK/DFS SDIO/DCS CSB
06216-001
8-STAGE 1 1/2-BIT PIPELINE 8
A/D 3
A/D
OR
APPLICATIONS
Ultrasound equipment IF sampling in communications receivers CDMA2000, WCDMA, TD-SCDMA, and WiMax Battery-powered instruments Hand-held scopemeters Low cost digital oscilloscopes Macro, micro, and pico cell infrastructure
AGND
CLK+
CLK-
PDWN
DRGND
Figure 1.
GENERAL DESCRIPTION
The AD9254 is a monolithic, single 1.8 V supply, 14-bit, 150 MSPS analog-to-digital converter (ADC), featuring a high performance sample-and-hold amplifier (SHA) and on-chip voltage reference. The product uses a multistage differential pipeline architecture with output error correction logic to provide 14-bit accuracy at 150 MSPS data rates and guarantees no missing codes over the full operating temperature range. The wide bandwidth, truly differential SHA allows a variety of user-selectable input ranges and offsets, including single-ended applications. It is suitable for multiplexed systems that switch full-scale voltage levels in successive channels and for sampling single-channel inputs at frequencies well beyond the Nyquist rate. Combined with power and cost savings over previously available ADCs, the AD9254 is suitable for applications in communications, imaging, and medical ultrasound. A differential clock input controls all internal conversion cycles. A duty cycle stabilizer (DCS) compensates for wide variations in the clock duty cycle while maintaining excellent overall ADC performance.
Rev. 0
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.
The digital output data is presented in offset binary, Gray code, or twos complement formats. A data output clock (DCO) is provided to ensure proper latch timing with receiving logic. The AD9254 is available in a 48-lead LFCSP_VQ and is specified over the industrial temperature range (-40C to +85C).
PRODUCT HIGHLIGHTS
1. The AD9254 operates from a single 1.8 V power supply and features a separate digital output driver supply to accommodate 1.8 V to 3.3 V logic families. The patented SHA input maintains excellent performance for input frequencies up to 225 MHz. The clock DCS maintains overall ADC performance over a wide range of clock pulse widths. A standard serial port interface supports various product features and functions, such as data formatting (offset binary, twos complement, or Gray coding), enabling the clock DCS, power-down, and voltage reference mode. The AD9254 is pin-compatible with the AD9233, allowing a simple migration from 12 bits to 14 bits.
2. 3. 4.
5.
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)2006 Analog Devices, Inc. All rights reserved.
AD9254 TABLE OF CONTENTS
Features .............................................................................................. 1 Applications....................................................................................... 1 General Description ......................................................................... 1 Functional Block Diagram .............................................................. 1 Product Highlights ........................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 DC Specifications ......................................................................... 3 AC Specifications.......................................................................... 4 Digital Specifications ................................................................... 5 Switching Specifications .............................................................. 6 Timing Diagram ........................................................................... 6 Absolute Maximum Ratings............................................................ 7 Thermal Resistance ...................................................................... 7 ESD Caution.................................................................................. 7 Pin Configuration and Function Descriptions............................. 8 Equivalent Circuits ........................................................................... 9 Typical Performance Characteristics ........................................... 10 Theory of Operation ...................................................................... 14 Analog Input Considerations.................................................... 14 Differential Input Configurations ............................................ 15 Voltage Reference ....................................................................... 16 Clock Input Considerations ...................................................... 17 Jitter Considerations .................................................................. 19 Power Dissipation and Standby Mode..................................... 19 Digital Outputs ........................................................................... 20 Timing ......................................................................................... 20 Serial Port Interface (SPI).............................................................. 21 Configuration Using the SPI..................................................... 21 Hardware Interface..................................................................... 21 Configuration Without the SPI ................................................ 21 Memory Map .................................................................................. 22 Reading the Memory Map Register Table............................... 22 Memory Map Register Table..................................................... 23 Layout Considerations................................................................... 25 Power and Ground Recommendations ................................... 25 CML ............................................................................................. 25 RBIAS........................................................................................... 25 Reference Decoupling................................................................ 25 Evaluation Board ............................................................................ 26 Power Supplies ............................................................................ 26 Input Signals................................................................................ 26 Output Signals ............................................................................ 26 Default Operation and Jumper Selection Settings................. 27 Alternative Clock Configurations............................................ 27 Alternative Analog Input Drive Configuration...................... 27 Schematics................................................................................... 29 Evaluation Board Layout........................................................... 34 Bill of Materials........................................................................... 37 Outline Dimensions ....................................................................... 40 Ordering Guide .......................................................................... 40
REVISION HISTORY
10/06--Revision 0: Initial Version
Rev. 0 | Page 2 of 40
AD9254 SPECIFICATIONS
DC SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 2.5 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = -1.0 dBFS, DCS enabled, unless otherwise noted. Table 1.
Parameter RESOLUTION ACCURACY No Missing Codes Offset Error Gain Error Differential Nonlinearity (DNL) 1 Integral Nonlinearity (INL)1 TEMPERATURE DRIFT Offset Error Gain Error INTERNAL VOLTAGE REFERENCE Output Voltage Error (1 V Mode) Load Regulation @ 1.0 mA INPUT REFERRED NOISE VREF = 1.0 V ANALOG INPUT Input Span, VREF = 1.0 V Input Capacitance 2 REFERENCE INPUT RESISTANCE POWER SUPPLIES Supply Voltage AVDD DRVDD Supply Current IAVDD1 IDRVDD1(DRVDD = 1.8 V) IDRVDD1 (DRVDD = 3.3 V) POWER CONSUMPTION DC Input Sine Wave Input1 (DRVDD = 1.8 V) Sine Wave Input1 (DRVDD = 3.3 V) Standby Power 3 Power-Down Power
1 2
Temperature Full Full Full Full 25C Full 25C Full Full Full Full Full 25C Full Full Full
Min 14
AD9254BCPZ-150 Typ Max
Unit Bits
Guaranteed 0.3 0.8 0.6 4.5 0.4 1.0 1.5 5.0 15 95 5 7 1.3 2 8 6 35
% FSR % FSR LSB LSB LSB LSB ppm/C ppm/C mV mV LSB rms V p-p pF k
Full Full Full Full Full Full Full Full Full Full
1.7 1.7
1.8 2.5 240 11 23 430 450 506 40 1.8
1.9 3.6 260
V V mA mA mA mW mW mW mW mW
470
Measured with a low input frequency, full-scale sine wave, with approximately 5 pF loading on each output bit. Input capacitance refers to the effective capacitance between one differential input pin and AGND. Refer to Figure 4 for the equivalent analog input structure. 3 Standby power is measured with a dc input, the CLK pin inactive (set to AVDD or AGND).
Rev. 0 | Page 3 of 40
AD9254
AC SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 2.5 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = -1.0 dBFS, DCS enabled, unless otherwise noted. Table 2.
Parameter 1 SIGNAL-TO-NOISE-RATIO (SNR) fIN = 2.4 MHz fIN = 70 MHz fIN = 100 MHz fIN = 170 MHz SIGNAL-TO-NOISE AND DISTORTION (SINAD) fIN = 2.4 MHz fIN = 70 MHz fIN = 100 MHz fIN = 170 MHz EFFECTIVE NUMBER OF BITS (ENOB) fIN = 2.4 MHz fIN = 70 MHz fIN = 100 MHz fIN = 170 MHz WORST SECOND OR THIRD HARMONIC fIN = 2.4 MHz fIN = 70 MHz fIN = 100 MHz fIN = 170 MHz SPURIOUS-FREE DYNAMIC RANGE (SFDR) fIN = 2.4 MHz fIN = 70 MHz fIN = 100 MHz fIN = 170 MHz WORST OTHER (HARMONIC OR SPUR) fIN = 2.4 MHz fIN = 70 MHz fIN = 100 MHz fIN = 170 MHz TWO-TONE SFDR fIN = 29 MHz (-7 dBFS ), 32 MHz (-7 dBFS ) fIN = 169 MHz (-7 dBFS ), 172 MHz (-7 dBFS ) ANALOG INPUT BANDWIDTH
1
Temperature 25C 25C Full 25C 25C 25C 25C Full 25C 25C 25C 25C 25C 25C 25C 25C Full 25C 25C 25C 25C Full 25C 25C 25C 25C Full 25C 25C 25C 25C 25C
Min
AD9254BCPZ-150 Typ Max 72.0 71.8
Unit dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc Bits Bits Bits Bits dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBc dBFS dBFS MHz
70.0 71.6 70.8 71.7 71.0 69.0 70.6 69.8 11.7 11.7 11.6 11.5 -90 -84 -74 -83 -80 90 84 74 83 80 -93 -93 -85 -90 -90 90 90 650
See Application Note AN-835, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions.
Rev. 0 | Page 4 of 40
AD9254
DIGITAL SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 2.5 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = -1.0 dBFS, 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 Voltage (VIH) Low Level Input Voltage (VIL) High Level Input Current (IIH) Low Level Input Current (IIL) Input Resistance Input Capacitance LOGIC INPUTS (SCLK/DFS, OEB, PWDN) High Level Input Voltage (VIH) Low Level Input Voltage (VIL) High Level Input Current (IIH) Low Level Input Current (IIL) Input Resistance Input Capacitance LOGIC INPUTS (CSB) High Level Input Voltage (VIH) Low Level Input Voltage (VIL) High Level Input Current (IIH) Low Level Input Current (IIL) Input Resistance Input Capacitance LOGIC INPUTS (SDIO/DCS) High Level Input Voltage (VIH) Low Level Input Voltage (VIL) High Level Input Current (IIH) Low Level Input Current (IIL) Input Resistance Input Capacitance DIGITAL OUTPUTS DRVDD = 3.3 V High Level Output Voltage (VOH, IOH = 50 A) High Level Output Voltage (VOH, IOH = 0.5 mA) Low Level Output Voltage (VOL, IOL = 1.6 mA) Low Level Output Voltage (VOL, IOL = 50 A) DRVDD = 1.8 V High Level Output Voltage (VOH, IOH = 50 A) High Level Output Voltage (VOH, IOH = 0.5 mA) Low Level Output Voltage (VOL, IOL = 1.6 mA) Low Level Output Voltage (VOL, IOL = 50 A) Temperature Min AD9254BCPZ-150 Typ CMOS/LVDS/LVPECL 1.2 0.2 AVDD - 0.3 1.1 1.2 0 -10 -10 8 6 AVDD + 1.6 AVDD 3.6 0.8 +10 +10 12 Max Unit
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
10 4
V V p-p V V V V A A k pF V V A A k pF V V A A k pF V V A A k pF
1.2 0 -50 -10 30 2 1.2 0 -10 +40 26 2 1.2 0 -10 +40 26 5
3.6 0.8 -75 +10
3.6 0.8 +10 +135
DRVDD + 0.3 0.8 +10 +130
Full Full Full Full Full Full Full Full
3.29 3.25 0.2 0.05 1.79 1.75 0.2 0.05
V V V V V V V V
Rev. 0 | Page 5 of 40
AD9254
SWITCHING SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 2.5 V, unless otherwise noted. Table 4.
Parameter 1 CLOCK INPUT PARAMETERS Conversion Rate, DCS Enabled Conversion Rate, DCS Disabled CLK Period CLK Pulse Width High, DCS Enabled CLK Pulse Width High, DCS Disabled DATA OUTPUT PARAMETERS Data Propagation Delay (tPD) 2 DCO Propagation Delay (tDCO) Setup Time (tS) Hold Time (tH) Pipeline Delay (Latency) Aperture Delay (tA) Aperture Uncertainty (Jitter, tJ) Wake-Up Time 3 OUT-OF-RANGE RECOVERY TIME SERIAL PORT INTERFACE 4 SCLK Period (tCLK) SCLK Pulse Width High Time (tHI) SCLK Pulse Width Low Time (tLO) SDIO to SCLK Setup Time (tDS) SDIO to SCLK Hold Time (tDH) CSB to SCLK Setup Time (tS) CSB to SCLK Hold Time (tH)
1 2 3
Temperature Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full Full
Min 20 10 6.7 2.0 3.0 3.1 1.9 3.0
AD9254BCPZ-150 Typ Max 150 150 3.3 3.3 3.9 4.4 2.9 3.8 12 0.8 0.1 350 3 4.7 3.7 4.8
Unit MSPS MSPS ns ns ns ns ns ns ns Cycles ns ps rms s Cycles ns ns ns ns ns ns ns
40 16 16 5 2 5 2
See Application Note AN-835, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions. Output propagation delay is measured from CLK 50% transition to DATA 50% transition, with 5 pF load. Wake-up time is dependent on the value of the decoupling capacitors, values shown with 0.1 F capacitor across REFT and REFB. 4 See Figure 50 and the Serial Port Interface (SPI) section.
TIMING DIAGRAM
N+1 N N+2 N+3 N+4
tA tCLK
N+8 N+5 N+6 N+7
CLK+ CLK-
tPD
DATA N - 13 N - 12 N - 11 N - 10 N-9 N-8 N-7 N-6 N-5 N-4
tS
DCO
Figure 2. Timing Diagram
Rev. 0 | Page 6 of 40
06216-002
tH
tDCO
tCLK
AD9254 ABSOLUTE MAXIMUM RATINGS
Table 5.
Parameter ELECTRICAL AVDD to AGND DRVDD to DGND AGND to DGND AVDD to DRVDD D0 through D13 to DGND DCO to DGND OR to DGND CLK+ to AGND CLK- to AGND VIN+ to AGND VIN- to AGND VREF to AGND SENSE to AGND REFT to AGND REFB to AGND SDIO/DCS to DGND PDWN to AGND CSB to AGND SCLK/DFS to AGND OEB to AGND ENVIRONMENTAL Storage Temperature Range Operating Temperature Range Lead Temperature (Soldering 10 Sec) Junction Temperature Rating -0.3 V to +2.0 V -0.3 V to +3.9 V -0.3 V to +0.3 V -3.9 V to +2.0 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 +3.9 V -0.3 V to +3.9 V -0.3 V to AVDD + 0.2 V -0.3 V to AVDD + 0.2 V -0.3 V to AVDD + 0.2 V -0.3 V to AVDD + 0.2 V -0.3 V to AVDD + 0.2 V -0.3 V to AVDD + 0.2 V -0.3 V to DRVDD + 0.3 V -0.3 V to +3.9 V -0.3 V to +3.9 V -0.3 V to +3.9 V -0.3 V to +3.9 V -65C to +125C -40C to +85C 300C 150C
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.
THERMAL RESISTANCE
The exposed paddle must be soldered to the ground plane for the LFCSP_VQ package. Soldering the exposed paddle to the customer board increases the reliability of the solder joints, maximizing the thermal capability of the package. Table 6. Thermal Resistance
Package Type 48-lead LFCSP_VQ (CP-48-3) JA 26.4 JC 2.4 Unit C/W
Typical JA and JC are specified for a 4-layer board in still air. Airflow increases heat dissipation, effectively reducing JA. In addition, metal in direct contact with the package leads from metal traces and through holes, ground, and power planes, reduces the JA.
ESD CAUTION
Rev. 0 | Page 7 of 40
AD9254 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
48 47 46 45 44 43 42 41 40 39 38 37 DRVDD DRGND D1 D0 (LSB) DCO OEB AVDD AGND AVDD CLK- CLK+ AGND
D2 D3
1 2
PIN 1 INDICATOR
D4 3 D5 4 D6 5 D7 6 DRGND 7 DRVDD 8 D8 9 D9 10 D10 11 D11 12
AD9254
TOP VIEW (Not to Scale)
36 35 34 33 32 31 30 29 28 27 26 25
PDWN RBIAS CML AVDD AGND VIN- VIN+ AGND REFT REFB VREF SENSE
D12 D13 (MSB) OR DRGND DRVDD SDIO/DCS SCLK/DFS CSB AGND AVDD AGND AVDD
13 14 15 16 17 18 19 20 21 22 23 24
Figure 3. Pin Configuration
Table 7. Pin Function Description
Pin No. 0, 21, 23, 29, 32, 37, 41 45, 46, 1 to 6, 9 to 14 7, 16, 47 8, 17, 48 15 18 19 20 22, 24, 33, 40, 42 25 26 27 28 30 31 34 35 36 38 39 43 44 Mnemonic AGND D0 (LSB) to D13 (MSB) DRGND DRVDD OR SDIO/DCS SCLK/DFS CSB AVDD SENSE VREF REFB REFT VIN+ VIN- CML RBIAS PDWN CLK+ CLK- OEB DCO Description Analog Ground. (Pin 0 is the exposed thermal pad on the bottom of the package.) Data Output Bits. Digital Output Ground. Digital Output Driver Supply (1.8 V to 3.3 V). Out-of-Range Indicator. Serial Port Interface (SPI) Data Input/Output (Serial Port Mode); Duty Cycle Stabilizer Select (External Pin Mode). See Table 10. Serial Port Interface Clock (Serial Port Mode); Data Format Select Pin (External Pin Mode). Serial Port Interface Chip Select (Active Low). See Table 10. Analog Power Supply. Reference Mode Selection. See Table 9. Voltage Reference Input/Output. Differential Reference (-). Differential Reference (+). Analog Input Pin (+). Analog Input Pin (-). Common-Mode Level Bias Output. External Bias Resistor Connection. A 10 k resistor must be connected between this pin and analog ground (AGND). Power-Down Function Select. Clock Input (+). Clock Input (-). Output Enable (Active Low). Data Clock Output.
Rev. 0 | Page 8 of 40
06216-003
AD9254 EQUIVALENT CIRCUITS
VIN
SCLK/DFS OEB PDWN
1k 30k
06216-004
Figure 4. Equivalent Analog Input Circuit
AVDD
Figure 8. Equivalent SCLK/DFS, OEB, PDWN Input Circuit
AVDD
1.2V CLK+ 10k 10k CLK-
26k CSB
1k
06216-005
Figure 5. Equivalent Clock Input Circuit
DRVDD
Figure 9. Equivalent CSB Input Circuit
SENSE 1k
1k SDIO/DCS
06216-006
Figure 6. Equivalent SDIO/DCS Input Circuit
DRVDD
Figure 10. Equivalent Sense Circuit
AVDD
VREF 6k
06216-011
DRGND
06216-007
Figure 7. Equivalent Digital Output Circuit
Figure 11. Equivalent VREF Circuit
Rev. 0 | Page 9 of 40
06216-010
06216-009
06216-008
AD9254 TYPICAL PERFORMANCE CHARACTERISTICS
AVDD = 1.8 V; DRVDD = 2.5 V; maximum sample rate, DCS enabled, 1 V internal reference; 2 V p-p differential input; AIN = -1.0 dBFS; 64k sample; TA = 25C, unless otherwise noted.
0 150MSPS 2.3MHz @ -1dBFS SNR = 72.0dBc (73.0dBFS) ENOB = 11.7 BITS SFDR = 90.0dBc
AMPLITUDE (dBFS)
0
-20
-20
150MSPS 100.3MHz @ -1dBFS SNR = 71.6dBc (72.6dBFS) ENOB = 11.6 BITS SFDR = 83dBc
AMPLITUDE (dBFS)
-40
-40
-60
-60
-80
-80
-100
-100
06216-012
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
Figure 12. AD9254 Single-Tone FFT with fIN = 2.3 MHz
0 0
Figure 15. AD9254 Single-Tone FFT with fIN = 100.3 MHz
-20
150MSPS 30.3MHz @ -1dBFS SNR = 71.9dBc (72.9dBFS) ENOB = 11.7 BITS SFDR = 88dBc
AMPLITUDE (dBFS)
-20
150MSPS 140.3MHz @ -1dBFS SNR = 71.5dBc (72.5dBFS) ENOB = 11.5 BITS SFDR = 81dBc
AMPLITUDE (dBFS)
-40
-40
-60
-60
-80
-80
-100
-100
06216-013
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
Figure 13. AD9254 Single-Tone FFT with fIN = 30.3 MHz
0 0
Figure 16. AD9254 Single-Tone FFT with fIN = 140.3 MHz
-20
150MSPS 70.3MHz @ -1dBFS SNR = 71.8dBc (72.8dBFS) ENOB = 11.7 BITS SFDR = 84dBc
AMPLITUDE (dBFS)
-20
150MSPS 170.3MHz @ -1dBFS SNR = 70.8dBc (71.8dBFS) ENOB = 11.5 BITS SFDR = 80dBc
AMPLITUDE (dBFS)
-40
-40
-60
-60
-80
-80
-100
-100
06216-014
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
Figure 14. AD9254 Single-Tone FFT with fIN = 70.3 MHz
Figure 17. AD9254 Single-Tone FFT with fIN = 170.3 MHz
Rev. 0 | Page 10 of 40
06216-017
-120
-120
06216-016
-120
-120
06216-015
-120
-120
AD9254
0 150MSPS 250.3MHz @ -1dBFS SNR = 69.3dBc (70.3dBFS) ENOB = 11.3 BITS SFDR = 79dBc 120 SFDR (dBFS) 100
SNR/SFDR (dBc and dBFS)
-20
AMPLITUDE (dBFS)
-40
80
SNR (dBFS)
-60
60
-80
40
SFDR (dBc)
-100
20 SNR (dBc)
06216-018
85dBc REFERENCE LINE
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
-80
-70
-60
-50
-40
-30
-20
-10
0
INPUT AMPLITUDE (dBFS)
Figure 18. AD9254 Single-Tone FFT with fIN = 250.3 MHz
0
Figure 21. AD9254 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with fIN = 2.4 MHz
0
-20
SFDR/WORST IMD3 (dBc and dBFS)
150MSPS fIN1 = 29.1MHz @ -7dBFS fIN2 = 32.1MHz @ -7dBFS SFDR = 83.2dBc (90.2dBFS) WoIMD3 = -83.9dBc (-90.9dBFS)
-20 SFDR (-dBc) -40 WORST IMD3 (dBc) -60
AMPLITUDE (dBFS)
-40
-60
-80
-80 SFDR (-dBFS) -100 WORST IMD3 (dBFS) -78 -66 -54 -42 -30 -18 -6 INPUT AMPLITUDE (dBFS)
06216-022 06216-023
-100
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
06216-019
-120
-120 -90
Figure 19. AD9254 Two-Tone FFT with fIN1 = 29.1 MHz, fIN2 = 32.1 MHz
90 SFDR -40C 85 SFDR +25C
SNR/SFDR (dBc)
Figure 22. AD9254 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 29.1 MHz, fIN2 = 32.1 MHz
90 SFDR +25C SFDR -40C 85
SNR/SFDR (dBc)
80
80 SFDR +85C
75 SNR -40C 70 SFDR +85C
75
70
SNR +25C
SNR -40C
65
SNR +25C
65 SNR +85C
06216-020
60
0
50
100
150
200
250
300
350
400
60
SNR +85C 0 50 100 150 200 250 300 350 400 INPUT FREQUENCY (MHz)
INPUT FREQUENCY (MHz)
Figure 20. AD9254 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and Temperature with 2 V p-p Full Scale
Figure 23. AD9254 Single-Tone SNR/SFDR vs. Input Frequency (fIN) and Temperature with 1 V p-p Full Scale
Rev. 0 | Page 11 of 40
06216-021
-120
0 -90
AD9254
0
2.0
-20
150MSPS fIN1 = 169.1MHz @ -7dBFS fIN2 = 172.1MHz @ -7dBFS SFDR = 83dBc (90dBFS) WoIMD3 = -83dBc (90dBFS)
1.5 1.0
AMPLITUDE (dBFS)
INL ERROR (LSB)
-40
0.5 0 -0.5 -1.0
-60
-80
-100
-1.5 -2.0
06216-024
0
18.75
37.50 FREQUENCY (MHz)
56.25
75.00
0
2048
4096
6144
8192
10240
12288
14336
16384
OUTPUT CODE
Figure 24. AD9254 Two-Tone FFT with fIN1 = 169.1 MHz, fIN2 = 172.1 MHz
95
12000
Figure 27. AD9254 INL with fIN = 10.3 MHz
32768 SAMPLES 1.25 LSB rms
90 SFDR
10000
NUMBER OF HITS
SNR/SFDR (dBc)
85
8000
80
6000
75 SNR 70
4000
2000
06216-025
20
30
40
50
60
70
80
90 100 110 120 130 140 150
N-5N-4N-3N-2N-1
N CODE
N+1N+2N+3N+4N+5
CLOCK FREQUENCY (MSPS)
Figure 25. AD9254 Single-Tone SNR/SFDR vs. Clock Frequency (fCLK) with fIN = 2.4 MHz
0
0
Figure 28. AD9254 Grounded Input Histogram
SFDR/WORST IMD3 (dBc and dBFS)
-20 SFDR (-dBc) -40
OFFSET ERROR -0.5
ERROR (%FS)
WORST IMD3 (dBc) -60
-1.0
-1.5 GAIN ERROR
-80 SFDR (-dBFS) -100 WORST IMD3 (dBFS)
06216-027
-2.0
-78
-66
-54
-42
-30
-18
-6
-20
0
20
40
60
80
INPUT AMPLITUDE (dBFS)
TEMPERATURE (C)
Figure 26. AD9254 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 169.1 MHz, fIN2 = 172.11 MHz
Figure 29. AD9254 Gain and Offset vs. Temperature
Rev. 0 | Page 12 of 40
06216-033
-120 -90
-2.5 -40
06216-032
65 10
0
06216-031
-120
AD9254
0.5 0.4 0.3
DNL ERROR (LSB)
0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 0 2048 4096 6144 8192 10240 12288 14336 16384
06216-034
-0.5
OTUPUT CODE
Figure 30. AD9254 DNL with fIN = 10.3 MHz
Rev. 0 | Page 13 of 40
AD9254 THEORY OF OPERATION
The AD9254 architecture consists of a front-end sample-andhold amplifier (SHA) 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 pipeline architecture permits the first stage to operate on a new input sample, while the remaining stages operate on 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 DAC and interstage residue amplifier (MDAC). The residue amplifier magnifies the difference between the reconstructed DAC output and the flash input for the next stage in the pipeline. One bit of redundancy is used in each stage to facilitate digital correction of flash errors. The last stage consists only of a flash ADC. The input stage contains a differential SHA that can be ac- or dc-coupled in differential or single-ended modes. The output staging block aligns the data, carries out the error correction, and passes the data to the output buffers. The output buffers are powered from a separate supply, allowing adjustment of the output voltage swing. During power-down, the output buffers go into a high impedance state.
S CH S CS VIN+ CPIN, PAR VIN- CPIN, PAR CH S H
CS
S
Figure 31. Switched-Capacitor SHA Input
For best dynamic performance, the source impedances driving VIN+ and VIN- should match such that common-mode settling errors are symmetrical. These errors are reduced by the common-mode rejection of the ADC. An internal differential reference buffer creates two reference voltages used to define the input span of the ADC core. The span of the ADC core is set by the buffer to be 2 x VREF. The reference voltages are not available to the user. Two bypass points, REFT and REFB, are brought out for decoupling to reduce the noise contributed by the internal reference buffer. It is recommended that REFT be decoupled to REFB by a 0.1 F capacitor, as described in the Layout Considerations section.
ANALOG INPUT CONSIDERATIONS
The analog input to the AD9254 is a differential switched capacitor SHA that has been designed for optimum performance while processing a differential input signal. The clock signal alternately switches the SHA between sample mode and hold mode (see Figure 31). When the SHA is switched into sample mode, the signal source must be capable of charging the sample capacitors and settling within one-half of a clock cycle. A small resistor in series with each input can help reduce the peak transient current 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 lowpass filter at the ADC input; therefore, the precise values are dependent upon the application. In IF undersampling applications, any shunt capacitors should be reduced. In combination with the driving source impedance, these capacitors would limit the input bandwidth. For more information, see Application Note AN-742, Frequency Domain Response of Switched-Capacitor ADCs; Application Note AN-827, A Resonant Approach to Interfacing Amplifiers to SwitchedCapacitor ADCs; and the Analog Dialogue article, "TransformerCoupled Front-End for Wideband A/D Converters."
Input Common Mode
The analog inputs of the AD9254 are not internally dc-biased. In ac-coupled applications, the user must provide this bias externally. Setting the device such that VCM = 0.55 x AVDD is recommended for optimum performance; however, the device functions over a wider range with reasonable performance (see Figure 30). An on-board common-mode voltage reference is included in the design and is available from the CML pin. Optimum performance is achieved when the common-mode voltage of the analog input is set by the CML pin voltage (typically 0.55 x AVDD). The CML pin must be decoupled to ground by a 0.1 F capacitor, as described in the Layout Considerations section.
Rev. 0 | Page 14 of 40
06216-035
AD9254
DIFFERENTIAL INPUT CONFIGURATIONS
Optimum performance is achieved by driving the AD9254 in a differential input configuration. For baseband applications, the AD8138 differential driver provides excellent performance and a flexible interface to the ADC. The output common-mode voltage of the AD8138 is easily set with the CML pin of the AD9254 (see Figure 32), and the driver can be configured in a Sallen-Key filter topology to provide band limiting of the input signal.
1V p-p 49.9 499 R 499 VIN+ C R 499 AVDD
As an alternative to using a transformer-coupled input at frequencies in the second Nyquist zone, the AD8352 differential driver can be used (see Figure 36). In any configuration, the value of the shunt capacitor, C, is dependent on the input frequency and source impedance and may need to be reduced or removed. Table 8 displays recommended values to set the RC network. However, these values are dependent on the input signal and should only be used as a starting guide. Table 8. RC Network Recommended Values
Frequency Range (MHz) 0 to 70 70 to 200 200 to 300 >300 R Series () 33 33 15 15 C Differential (pF) 15 5 5 Open
AD8138
0.1F 523
AD9254
06216-036
VIN-
CML
Figure 32. Differential Input Configuration Using the AD8138
Single-Ended Input Configuration
Although not recommended, it is possible to operate the AD9254 in a single-ended input configuration, as long as the input voltage swing is within the AVDD supply. Single-ended operation can provide adequate performance in cost-sensitive applications. In this configuration, SFDR and distortion performance degrade due to the large input common-mode swing. If the source impedances on each input are matched, there should be little effect on SNR performance. Figure 34 details a typical single-ended input configuration.
10F AVDD 1k R 1V p-p 49.9 0.1F 1k C R VIN+
For baseband applications where SNR is a key parameter, differential transformer coupling is the recommended input configuration (see Figure 33). The CML voltage can be connected to the center tap of the secondary winding of the transformer to bias the analog input. The signal characteristics must be considered when selecting a transformer. Most RF transformers saturate at frequencies below a few megahertz, and excessive signal power can cause core saturation, which leads to distortion.
R VIN+ C R
2V p-p
49.9
AD9254
VIN- CML
AVDD 1k 10F 0.1F 1k
AD9254
VIN-
06216-038
0.1F
Figure 33. Differential Transformer-Coupled Configuration
06216-037
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 AD9254. For applications where SNR is a key parameter, transformer coupling is the recommended input. For applications where SFDR is a key parameter, differential double balun coupling is the recommended input configuration (see Figure 35).
Figure 34. Single-Ended Input Configuration
Rev. 0 | Page 15 of 40
AD9254
0.1F 2V p-p 25 PA S S P 0.1F 25 0.1F R C 0.1F R VIN+
AD9254
VIN- CML
06216-039
Figure 35. Differential Double Balun Input Configuration
VCC
0.1F 0.1F 0 16 1 2 200 CD RD RG 3 4 5 0.1F 0 14 0.1F
06216-040
8, 13 11
0.1F
R VIN+ C R
AD8352
10 0.1F
200
AD9254
VIN- CML
0.1F
Figure 36. Differential Input Configuration Using the AD8352
Table 9. Reference Configuration Summary
Selected Mode External Reference Internal Fixed Reference Programmable Reference Internal Fixed Reference SENSE Voltage AVDD VREF 0.2 V to VREF AGND to 0.2 V Resulting VREF (V) N/A 0.5 Resulting Differential Span (V p-p) 2 x external reference 1.0 2 x VREF 2.0
R2 0.5 x 1 + (see Figure 38) R1
1.0
VOLTAGE REFERENCE
A stable and accurate voltage reference is built into the AD9254. The input range is adjustable by varying the reference voltage applied to the AD9254, using either the internal reference or an externally applied reference voltage. The input span of the ADC tracks reference voltage changes linearly. The various reference modes are summarized in the following sections. The Reference Decoupling section describes the best practices and requirements for PCB layout of the reference.
Connecting the SENSE pin to VREF switches the reference amplifier input to the SENSE pin, completing the loop and providing a 0.5 V reference output. If a resistor divider is connected external to the chip, as shown in Figure 38, the switch sets to the SENSE pin. This puts the reference amplifier in a noninverting mode with the VREF output defined as
R2 VREF = 0.5 1 + R1
Internal Reference Connection
A comparator within the AD9254 detects the potential at the SENSE pin and configures the reference into four possible states, as summarized in Table 9. If SENSE is grounded, the reference amplifier switch is connected to the internal resistor divider (see Figure 37), setting VREF to 1 V.
If the SENSE pin is connected to AVDD, the reference amplifier is disabled, and an external reference voltage can be applied to the VREF pin (see the External Reference Operation section). The input range of the ADC always equals twice the voltage at the reference pin for either an internal or an external reference.
Rev. 0 | Page 16 of 40
AD9254
VIN+ VIN-
-
ADC CORE
External Reference Operation
REFT
-
0.1F
The use of an external reference may be necessary to enhance the gain accuracy of the ADC or improve thermal drift characteristics. Figure 40 shows the typical drift characteristics of the internal reference in both 1 V and 0.5 V modes.
10
REFB VREF SELECT LOGIC SENSE 0.5V
06216-041
REFERENCE VOLTAGE ERROR (mV)
0.1F
0.1F
8
VREF = 1V
6
VREF = 0.5V
AD9254
Figure 37. Internal Reference Configuration
4
2
VIN+ VIN-
-
REFT
-20
0
20
40
60
80
TEMPERATURE (C)
0.1F
Figure 40. Typical VREF Drift
REFB VREF 0.1F 0.1F R2 SENSE SELECT LOGIC
R1
0.5V
06216-042
When the SENSE pin is tied to AVDD, the internal reference is disabled, allowing the use of an external reference. An internal resistor divider loads the external reference with an equivalent 6 k load (see Figure 11). In addition, an internal buffer generates the positive and negative full-scale references for the ADC core. Therefore, the external reference must be limited to a maximum of 1 V.
AD9254
Figure 38. Programmable Reference Configuration
CLOCK INPUT CONSIDERATIONS
For optimum performance, the AD9254 sample clock inputs (CLK+ and CLK-) should be clocked with a differential signal. The signal is typically ac-coupled into the CLK+ pin and the CLK- pin via a transformer or capacitors. These pins are biased internally (see Figure 5) and require no external bias.
If the internal reference of the AD9254 is used to drive multiple converters to improve gain matching, the loading of the reference by the other converters must be considered. Figure 39 depicts how the internal reference voltage is affected by loading.
0 VREF = 0.5V
Clock Input Options
The AD9254 has a very flexible clock input structure. The clock input can be a CMOS, LVDS, LVPECL, or sine wave signal. Regardless of the type of signal used, the jitter of the clock source is of the most concern, as described in the Jitter Considerations section. Figure 41 shows one preferred method for clocking the AD9254. A low jitter clock source is converted from singleended to a differential signal using an RF transformer. The back-to-back Schottky diodes across the transformer secondary limit clock excursions into the AD9254 to approximately 0.8 V p-p differential. This helps prevent the large voltage swings of the clock from feeding through to other portions of the AD9254, while preserving the fast rise and fall times of the signal, which are critical to a low jitter performance.
REFERENCE VOLTAGE ERROR (%)
-0.25 VREF = 1V -0.50
-0.75
-1.00
0
0.5
1.0 LOAD CURRENT (mA)
1.5
2.0
Figure 39. VREF Accuracy vs. Load
06216-043
-1.25
Rev. 0 | Page 17 of 40
06216-044
ADC CORE
-
0 -40
AD9254
0.1F CLOCK INPUT 50 MINI-CIRCUITS ADT1-1WT, 1:1Z 0.1F XFMR 100 0.1F 0.1F SCHOTTKY DIODES: HMS2812
VCC 0.1F CLOCK INPUT 1k 1k AD951x CMOS DRIVER OPTIONAL 0.1F 100 CLK+
CLK+
ADC AD9254
06216-045
501
ADC AD9254
CLK- 0.1F
06216-048
CLK-
39k
Figure 41. Transformer Coupled Differential Clock
150
RESISTOR IS OPTIONAL.
Figure 44. Single-Ended 1.8 V CMOS Sample Clock
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 42. The AD9510/AD9511/AD9512/ AD9513/AD9514/AD9515 family of clock drivers offers excellent jitter performance.
VCC CLOCK INPUT 0.1F 501 1k 1k 0.1F AD951x CMOS DRIVER OPTIONAL 0.1F 100 CLK+
ADC AD9254
06216-049
CLK-
0.1F CLK AD951x 0.1F PECL DRIVER CLK 501
150
CLOCK INPUT
0.1F CLK+ 100 0.1F 240
06216-046
150 RESISTOR IS OPTIONAL.
ADC AD9254
CLK-
Figure 45. Single-Ended 3.3 V CMOS Sample Clock
Clock Duty Cycle
Typical high speed ADCs use both clock edges to generate a variety of internal timing signals. As a result, these ADCs may be sensitive to clock duty cycle. Commonly, a 5% tolerance is required on the clock duty cycle to maintain dynamic performance characteristics. The AD9254 contains a duty cycle stabilizer (DCS) that retimes the nonsampling, or falling edge, providing an internal clock signal with a nominal 50% duty cycle. This allows a wide range of clock input duty cycles without affecting the performance of the AD9254. Noise and distortion performance are nearly flat for a wide range of duty cycles when the DCS is on, as shown in Figure 28. Jitter in the rising edge of the input is still of paramount concern and is not reduced by the internal stabilization circuit. The duty cycle control loop does not function for clock rates less than 20 MHz nominally. The loop has a time constant associated with it that needs to be considered in applications where the clock rate can change dynamically. This requires a wait time of 1.5 s to 5 s after a dynamic clock frequency increase (or decrease) before the DCS loop is relocked to the input signal. During the time period the loop is not locked, the DCS loop is bypassed, and the internal device timing is dependent on the duty cycle of the input clock signal. In such an application, it may be appropriate to disable the duty cycle stabilizer. In all other applications, enabling the DCS circuit is recommended to maximize ac performance.
CLOCK INPUT
501
240
RESISTORS ARE OPTIONAL.
Figure 42. Differential PECL Sample Clock
A third option is to ac-couple a differential LVDS signal to the sample clock input pins, as shown in Figure 43. The AD9510/ AD9511/AD9512/AD9513/AD9514/AD9515 family of clock drivers offers excellent jitter performance.
0.1F CLOCK INPUT CLK AD951x 0.1F LVDS DRIVER CLK 501 501
0.1F CLK+ 100 0.1F
ADC AD9254
CLK-
06216-047
CLOCK INPUT
150 RESISTORS ARE OPTIONAL.
Figure 43. Differential LVDS Sample Clock
In some applications, it is acceptable to drive the sample clock inputs with a single-ended CMOS signal. In such applications, directly drive CLK+ from a CMOS gate, while bypassing the CLK- pin to ground using a 0.1 F capacitor in parallel with a 39 k resistor (see Figure 44). CLK+ can be directly driven from a CMOS gate. This input is designed to withstand input voltages up to 3.6 V, making the selection of the drive logic voltage very flexible. When driving CLK+ with a 1.8 V CMOS signal, biasing the CLK- pin with a 0.1 F capacitor in parallel with a 39 k resistor (see Figure 44) is required. The 39 k resistor is not required when driving CLK+ with a 3.3 V CMOS signal (see Figure 45).
Rev. 0 | Page 18 of 40
AD9254
The DCS can be enabled or disabled by setting the SDIO/DCS pin when operating in the external pin mode (see Table 10), or via the SPI, as described in Table 13. Table 10. Mode Selection (External Pin Mode)
Voltage at Pin AGND AVDD SCLK/DFS Binary (default) Twos complement SDIO/DCS DCS disabled DCS enabled (default)
POWER DISSIPATION AND STANDBY MODE
The power dissipated by the AD9254 is proportional to its sample rate (see Figure 47). The digital power dissipation is determined primarily by the strength of the digital drivers and the load on each output bit. Maximum DRVDD current (IDRVDD) can be calculated as
I DRVDD = VDRVDD x CLOAD x
fCLK xN 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) is calculated as follows: SNR = -20 log (2 x fIN x tJ) In the equation, the rms aperture jitter represents the root mean square of all jitter sources, which include the clock input, analog input signal, and ADC aperture jitter specification. IF undersampling applications are particularly sensitive to jitter, as shown in Figure 46.
75
where N is the number of output bits, 14 in the AD9254. This maximum current occurs when every output bit switches on every clock cycle, that is, a full-scale square wave at the Nyquist frequency, fCLK/2. In practice, the DRVDD current is established by the average number of output bits switching, which is determined by the sample rate and the characteristics of the analog input signal. Reducing the capacitive load presented to the output drivers can minimize digital power consumption. The data in Figure 47 was taken under the same operating conditions as the data for the Typical Performance Characteristics section, with a 5 pF load on each output driver.
500 480
0.05ps
300
70 MEASURED PERFORMANCE
460 I (AVDD) 440
POWER (mW)
0.20ps
250
420 400 POWER 380 360 340 320 300 0 I (DRVDD) 100 150
60 0.5ps 55 1.0ps 50 1.50ps 45 40 2.00ps 2.50ps 3.00ps 1 10 100 1000
06216-050
50
CLOCK FREQUENCY (MHz)
INPUT FREQUENCY (MHz)
Figure 46. SNR vs. Input Frequency and Jitter
Figure 47. AD9254 Power and Current vs. Clock Frequency fIN = 30 MHz
Power-Down Mode
Treat the clock input as an analog signal in cases where aperture jitter can affect the dynamic range of the AD9254. Power supplies for clock drivers should be separated from the ADC output driver supplies to avoid modulating the clock signal with digital noise. The power supplies should also not be shared with analog input circuits, such as buffers, to avoid the clock modulating onto the input signal or vice versa. Low jitter, crystal-controlled oscillators make the best clock sources. If the clock is generated from another type of source (by gating, dividing, or other methods), it should be retimed by the original clock at the last step. Refer to Application Notes AN-501, Aperture Uncertainty and ADC System Performance; and AN-756, Sampled Systems and the Effects of Clock Phase Noise and Jitter, for more in-depth information about jitter performance as it relates to ADCs.
By asserting the PDWN pin high, the AD9254 is placed in powerdown mode. In this state, the ADC typically dissipates 1.8 mW. During power-down, the output drivers are placed in a high impedance state. Reasserting the PDWN pin low returns the AD9254 to its normal operational mode. This pin is both 1.8 V and 3.3 V tolerant. Low power dissipation in power-down mode is achieved by shutting down the reference, reference buffer, biasing networks, and clock. The decoupling capacitors on REFT and REFB are discharged when entering power-down mode and then must be recharged when returning to normal operation. As a result, the 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. With the recommended 0.1 F decoupling capacitors on REFT and REFB, it takes approximately 0.25 ms to fully discharge the reference buffer decoupling capacitors and 0.35 ms to restore full operation.
Rev. 0 | Page 19 of 40
06216-051
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
CURRENT (mA)
65
200
SNR (dBc)
AD9254
Standby Mode
When using the SPI port interface, the user can place the ADC in power-down or standby modes. Standby mode allows the user to keep the internal reference circuitry powered when faster wake-up times are required (see the Memory Map section). By logically AND'ing the OR bit with the MSB and its complement, overrange high or underrange low conditions can be detected. Table 11 is a truth table for the overrange/underrange circuit in Figure 49, which uses NAND gates.
MSB OR MSB UNDER = 1
06216-053
OVER = 1
DIGITAL OUTPUTS
The AD9254 output drivers can be configured to interface with 1.8 V to 3.3 V logic families by matching DRVDD to the digital supply of the interfaced logic. The output drivers are sized to provide sufficient output current to drive a wide variety of logic families. However, large drive currents tend to cause current glitches on the supplies that may affect converter performance. Applications requiring the ADC to drive large capacitive loads or large fan-outs may require external buffers or latches. The output data format can be selected for either offset binary or twos complement by setting the SCLK/DFS pin when operating in the external pin mode (see Table 10). As detailed in the Interfacing to High Speed ADCs via SPI user manual, the data format can be selected for either offset binary, twos complement, or Gray code when using the SPI control.
Figure 49. Overrange/Underrange Logic
Table 11. Overrange/Underrange Truth Table
OR 0 0 1 1 MSB 0 1 0 1 Analog Input Is: Within range Within range Underrange Overrange
Digital Output Enable Function (OEB)
The AD9254 has three-state ability. 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 is not intended for rapid access to the data bus. Note that OEB is referenced to the digital supplies (DRVDD) and should not exceed that supply voltage.
Out-of-Range (OR) Condition
An out-of-range condition exists when the analog input voltage is beyond the input range of the ADC. OR is a digital output that is updated along with the data output corresponding to the particular sampled input voltage. Thus, OR has the same pipeline latency as the digital data.
OR DATA OUTPUTS 1 11 1111 1111 1111 0 11 1111 1111 1111 0 11 1111 1111 1110 +FS - 1 LSB OR
TIMING
The lowest typical conversion rate of the AD9254 is 10 MSPS. At clock rates below 10 MSPS, dynamic performance can degrade. The AD9254 provides latched data outputs with a pipeline delay of twelve 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 the loads placed on them should be minimized to reduce transients within the AD9254. These transients can degrade the dynamic performance of the converter.
-FS + 1/2 LSB 0 0 1 00 0000 0000 0001 00 0000 0000 0000 00 0000 0000 0000 -FS -FS - 1/2 LSB +FS +FS - 1/2 LSB
06216-052
Data Clock Output (DCO)
The AD9254 also provides data clock output (DCO) intended for capturing the data in an external register. The data outputs are valid on the rising edge of DCO, unless the DCO clock polarity has been changed via the SPI. See Figure 2 for a graphical timing description.
Figure 48. OR Relation to Input Voltage and Output Data
OR is low when the analog input voltage is within the analog input range and high when the analog input voltage exceeds the input range, as shown in Figure 48. OR remains high until the analog input returns to within the input range and another conversion is completed. Table 12. Output Data Format
Input (V) VIN+ - VIN- VIN+ - VIN- VIN+ - VIN- VIN+ - VIN- VIN+ - VIN- Condition (V) < -VREF - 0.5 LSB = -VREF =0 = +VREF - 1.0 LSB > +VREF - 0.5 LSB 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 10 0000 0000 0000 10 0000 0000 0000 00 0000 0000 0000 01 1111 1111 1111 01 1111 1111 1111
Gray Code Mode (SPI Accessible) 11 0000 0000 0000 11 0000 0000 0000 00 0000 0000 0000 10 0000 0000 0000 10 0000 0000 0000
OR 1 0 0 0 1
Rev. 0 | Page 20 of 40
AD9254 SERIAL PORT INTERFACE (SPI)
The AD9254 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. This provides the user added flexibility and customization depending on the application. Addresses are accessed via the serial port and may be written to or read from via the port. Memory is organized into bytes that are further divided into fields, as documented in the Memory Map section. For detailed operational information, see the Interfacing to High Speed ADCs via SPI user manual. In addition to word length, the instruction phase determines if the serial frame is a read or write operation, allowing the serial port to be used to both program the chip as well as 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- or in LSB-first mode. MSB first is the default on power-up and can be changed via the configuration register. For more information, see the Interfacing to High Speed ADCs via SPI user manual. Table 14. SPI Timing Diagram Specifications
Name tDS tDH tCLK tS tH tHI tLO Description Setup time between data and rising edge of SCLK Hold time between data and rising edge of SCLK Period of the clock 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
CONFIGURATION USING THE SPI
As summarized in Table 13, three pins define the SPI of this ADC. The SCLK/DFS pin synchronizes the read and write data presented to the ADC. The SDIO/DCS dual-purpose pin allows data to be sent to and read from the internal ADC memory map registers. The CSB pin is an active low control that enables or disables the read and write cycles. Table 13. Serial Port Interface Pins
Pin Name SCLK/DFS SDIO/DCS Function SCLK (serial clock) is the serial shift clock in. SCLK synchronizes serial interface reads and writes. SDIO (serial data input/output) is a dual-purpose pin. The typical role for this pin is an input and output, depending on the instruction being sent and the relative position in the timing frame. CSB (chip select bar) is an active-low control that gates the read and write cycles.
HARDWARE INTERFACE
The pins described in Table 13 comprise the physical interface between the user's programming device and the serial port of the AD9254. The SCLK and CSB pins 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 PROM or PIC microcontrollers. This provides the user with the ability to use an alternate method to program the ADC. One method is described in detail in Application Note AN-812, Microcontroller-Based Serial Port Interface Boot Circuit. When the SPI interface is not used, some pins serve a dual function. When strapped to AVDD or ground during device power on, the pins are associated with a specific function.
CSB
The falling edge of the CSB in conjunction with the rising edge of the SCLK determines the start of the framing. Figure 50 and Table 14 provide examples of the serial timing and its definitions. Other modes involving the CSB are available. The CSB can be held low indefinitely to permanently enable 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 the length is determined by the W0 bit and the W1 bit. 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.
CONFIGURATION WITHOUT THE SPI
In applications that do not interface to the SPI control registers, the SDIO/DCS and SCLK/DFS pins serve as stand-alone CMOS-compatible control pins. When the device is powered up, it is assumed that the user intends to use the pins as static control lines for the output data format and duty cycle stabilizer (see Table 10). In this mode, the CSB chip select should be connected to AVDD, which disables the serial port interface. For more information, see the Interfacing to High Speed ADCs via SPI user manual.
Rev. 0 | Page 21 of 40
AD9254 MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Each row in the memory map register table has eight address locations. The memory map is roughly divided into three sections: the chip configuration registers map (Address 0x00 to Address 0x02), the device index and transfer registers map (Address 0xFF), and the ADC functions map (Address 0x08 to Address 0x18). Table 15 displays the register address number in hexadecimal in the first column. The last column displays the default value for each hexadecimal address. The Bit 7 (MSB) column is the start of the default hexadecimal value given. For example, Hexadecimal Address 0x14, output_phase, has a hexadecimal default value of 0x00. This means Bit 3 = 0, Bit 2 = 0, Bit 1 = 1, and Bit 0 = 1 or 0011 in binary. This setting is the default output clock or DCO phase adjust option. The default value adjusts the DCO phase 90 relative to the nominal DCO edge and 180 relative to the data edge. For more information on this function, consult the Interfacing to High Speed ADCs via SPI user manual.
Default Values
Coming out of reset, critical registers are loaded with default values. The default values for the registers are shown in Table 15.
Logic Levels
An explanation of two registers 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."
SPI-Accessible Features
A list of features accessible via the SPI and a brief description of what the user can do with these features follows. These features are described in detail in the Interfacing to High Speed ADCs via SPI user manual. * * * * * * * Modes: Set either power-down or standby mode. Clock: Access the DCS via the SPI. Offset: Digitally adjust the converter offset. Test I/O: Set test modes to have known data on output bits. Output Mode: Setup outputs, vary the strength of the output drivers. Output Phase: Set the output clock polarity. VREF: Set the reference voltage.
Open Locations
Locations marked as open are currently not supported for this device. When required, these locations should be written with 0s. Writing to these locations is required only when part of an address location is open (for example, Address 0x14). If the entire address location is open (Address 0x13), then the address location does not need to be written.
tDS tS
CSB
tHI tDH tLO
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 50. Serial Port Interface Timing Diagram
Rev. 0 | Page 22 of 40
06216-054
AD9254
MEMORY MAP REGISTER TABLE
Table 15. Memory Map Register
Addr. Bit 7 (Hex) Parameter Name (MSB) Chip Configuration Registers 00 chip_port_config 0 Bit 6 LSB first 0 = Off (Default) 1 = On Bit 5 Soft reset 0 = Off (Default) 1 = On Bit 4 1 Bit 3 1 Bit 2 Soft reset 0 = Off (Default) 1 = On Bit 1 LSB first 0 = Off (Default) 1 = On Bit 0 (LSB) 0 Default Value (Hex) 0x18 Default Notes/ Comments The nibbles should be mirrored. See the Interfacing to High Speed ADCs via SPI user manual. Default is unique chip ID, different for each device. Child ID used to differentiate speed grades. Synchronously transfers data from the master shift register to the slave. Determines various generic modes of chip operation. See the Power
01
chip_id
8-bit Chip ID Bits 7:0 (AD9254 = 0x00), (default) Open Open Open Open Child ID 0 = 150 MSPS Open Open Open Open
Read only Read only
02
chip_grade
Device Index and Transfer Registers FF device_update Open
Open
Open
Open
Open
Open
SW transfer
0x00
Global ADC Functions 08 modes
Open
Open
PDWN 0--Full 1-- Standby
Open
Open
Internal power-down mode 000--normal (power-up) 001--full power-down 010--standby 011--normal (power-up) Note: External PDWN pin overrides this setting.
0x00
Dissipation and Standby Mode and the SPIAccessible Features
sections. 0x01 See the Clock
09
clock
Open
Open
Open
Open
Open
Open
Open
Duty cycle stabilizer 0-- disabled 1-- enabled
Duty Cycle
section and the
SPI-Accessible Features section.
Rev. 0 | Page 23 of 40
AD9254
Addr. Bit 7 (Hex) Parameter Name (MSB) Flexible ADC Functions 10 offset Bit 0 (LSB) Default Value (Hex) 0x00 Default Notes/ Comments Adjustable for offset inherent in the converter. See
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
0D
test_io
Digital Offset Adjust<5:0> 011111 011110 011101 ... 000010 000001 000000 111111 111110 111101 ... 100001 100000 PN9 PN23 0 = normal 0 = normal (Default) (Default) 1 = reset 1 = reset
Offset in LSBs +31 +30 +29 +2 +1 0 (Default) 1 -2 -3 -31 -32 Global Output Test Options 000--off 001--midscale short 010--+FS short 011---FS short 100--checker board output 101--PN 23 sequence 110--PN 9 111--one/zero word toggle Data Format Select Output 00--offset binary Data (default) Invert 01--twos 1= complement invert 10--Gray Code Open Open Open
SPIAccessible Features
section.
0x00
See the Interfacing to High Speed ADCs via SPI user manual.
14
output_mode
Output Driver Configuration 00 for DRVDD = 2.5 V to 3.3 V 10 for DRVDD = 1.8 V Open Output Clock Polarity 1 = inverted 0 = normal (Default) Internal Reference Resistor Divider 00--VREF = 1.25 V 01--VREF = 1.5 V 10--VREF = 1.75 V 11--VREF = 2.00 V (Default)
Open
16
output_phase
Open
Output Disable 1-- disabled 0-- enabled 1 Open
Open
0x00
Configures the outputs and the format of the data.
Open
0x00
See the SPIAccessible Features section. See the SPIAccessible Features section.
18
VREF
Open
Open
Open
Open
Open
Open
0xC0
1
External output enable (OEB) pin must be high.
Rev. 0 | Page 24 of 40
AD9254 LAYOUT CONSIDERATIONS
POWER AND GROUND RECOMMENDATIONS
When connecting power to the AD9254, it is recommended that two separate supplies be used: one for analog (AVDD, 1.8 V nominal) and one for digital (DRVDD, 1.8 V to 3.3 V nominal). If only a single 1.8 V supply is available, it is routed to AVDD first, then tapped off and isolated with a ferrite bead or filter choke with decoupling capacitors proceeding connection to DRVDD. The user can employ several different decoupling capacitors to cover both high and low frequencies. These should be located close to the point of entry at the PC board level and close to the parts with minimal trace length. A single PC board ground plane is sufficient when using the AD9254. With proper decoupling and smart partitioning of analog, digital, and clock sections of the PC board, optimum performance is easily achieved.
SILKSCREEN PARTITION PIN 1 INDICATOR
Figure 51. Typical PCB Layout
CML
The CML pin should be decoupled to ground with a 0.1 F capacitor, as shown in Figure 33.
RBIAS
The AD9254 requires the user to place a 10 k resistor between the RBIAS pin and ground. This resister sets the master current reference of the ADC core and should have at least a 1% tolerance.
Exposed Paddle Thermal Heat Slug Recommendations
It is required that the exposed paddle on the underside of the ADC be connected to analog ground (AGND) to achieve the best electrical and thermal performance of the AD9254. An exposed, continuous copper plane on the PCB should mate to the AD9254 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 solder-filled or plugged. To maximize the coverage and adhesion between the ADC and PCB, partition the continuous plane by overlaying a silkscreen on the PCB into several uniform sections. This provides several tie points between the two during the reflow process. Using one continuous plane with no partitions guarantees only one tie point between the ADC and PCB. See Figure 51 for a PCB layout example. For detailed information on packaging and the PCB layout of chip scale packages, see Application Note AN-772, A Design and Manufacturing Guide for the Lead Frame Chip Scale Package.
REFERENCE DECOUPLING
The VREF pin should be externally decoupled to ground with a low ESR 1.0 F capacitor in parallel with a 0.1 F ceramic low ESR capacitor. In all reference configurations, REFT and REFB are bypass points provided for reducing the noise contributed by the internal reference buffer. It is recommended that an external 0.1 F ceramic capacitor be placed across REFT/REFB. While placement of this 0.1 F capacitor is not required, the SNR performance degrades by approximately 0.1 dB without it. All reference decoupling capacitors should be placed as close to the ADC as possible with minimal trace lengths.
Rev. 0 | Page 25 of 40
06216-055
AD9254 EVALUATION BOARD
The AD9254 evaluation board provides all of the support circuitry required to operate the ADC in its various modes and configurations. The converter can be driven differentially through a double balun configuration (default) or through the AD8352 differential driver. The ADC can also be driven in a single-ended fashion. Separate power pins are provided to isolate the DUT from the AD8352 drive circuitry. Each input configuration can be selected by proper connection of various components (see Figure 53 to Figure 63). Figure 52 shows the typical bench characterization setup used to evaluate the ac performance of the AD9254. It is critical that the signal sources used for the analog input and clock have very low phase noise (<1 ps rms jitter) to realize the optimum performance of the converter. Proper filtering of the analog input signal to remove harmonics and lower the integrated or broadband noise at the input is also necessary to achieve the specified noise performance. See Figure 53 to Figure 57 for the complete schematics and layout diagrams that demonstrate the routing and grounding techniques that should be applied at the system level. When operating the evaluation board in a nondefault condition, L501, L503, L504, L508, and L509 can be removed to disconnect the switching power supply. This enables the user to individually bias each section of the board. Use P501 to connect a different supply for each section. At least one 1.8 V supply is needed with a 1 A current capability for AVDD_DUT and DRVDD_DUT; however, it is recommended that separate supplies be used for analog and digital. To operate the evaluation board using the AD8352 option, a separate 5.0 V supply (AMP_VDD) with a 1 A current capability is needed. To operate the evaluation board using the alternate SPI options, a separate 3.3 V analog supply is needed, in addition to the other supplies. The 3.3 V supply (AVDD_3.3V) should have a 1 A current capability as well. Solder Jumpers J501, J502, and J505 allow the user to combine these supplies (see Figure 57 for more details).
INPUT SIGNALS
When connecting the clock and analog source, use clean signal generators with low phase noise, such as Rohde & Schwarz SMHU or Agilent HP8644 signal generators or the equivalent. Use one meter long, shielded, RG-58, 50 coaxial cable for making connections to the evaluation board. Enter the desired frequency and amplitude for the ADC. Typically, most evaluation boards from Analog Devices, Inc. can accept a ~2.8 V p-p or 13 dBm sine wave input for the clock. When connecting the analog input source, it is recommended to use a multipole, narrowband, band-pass filter with 50 terminations. Analog Devices uses TTE(R), Allen Avionics, and K&L(R) types of band-pass filters. Connect the filter directly to the evaluation board, if possible.
POWER SUPPLIES
This evaluation board comes with a wall-mountable switching power supply that provides a 6 V, 2 A maximum output. Connect the supply to the rated 100 V ac to 240 V ac wall outlet at 47 Hz to 63 Hz. The other end is a 2.1 mm inner diameter jack that connects to the PCB at P500. Once on the PC board, the 6 V supply is fused and conditioned before connecting to five low dropout linear regulators that supply the proper bias to each of the various sections on the board.
OUTPUT SIGNALS
The parallel CMOS outputs interface directly with the Analog Devices standard single-channel FIFO data capture board (HSC-ADC-EVALB-SC). For more information on the FIFO boards and their optional settings, visit www.analog.com/FIFO.
WALL OUTLET 100V TO 240V AC 47Hz TO 63Hz 6V DC 2A MAX SWITCHING POWER SUPPLY -
5.0V + -
1.8V +
2.5V - + -
3.3V + -
3.3V + -
3.3V +
GND
VDL
GND
GND
GND
GND
AMP_VDD
GND
DRVDD_DUT
AVDD_3.3V
AVDD_DUT
VCC
ROHDE & SCHWARZ, SMHU, 2V p-p SIGNAL SYNTHESIZER ROHDE & SCHWARZ, SMHU, 2V p-p SIGNAL SYNTHESIZER
BAND-PASS FILTER
AIN
AD9254
EVALUATION BOARD
CLK
14-BIT PARALLEL CMOS SPI
SPI
SPI
Figure 52. Evaluation Board Connection
Rev. 0 | Page 26 of 40
06216-056
HSC-ADC-EVALB-SC FIFO DATA CAPTURE BOARD USB CONNECTION
PC RUNNING ADC ANALYZER AND SPI USER SOFTWARE
AD9254
DEFAULT OPERATION AND JUMPER SELECTION SETTINGS
The following is a list of the default and optional settings or modes allowed on the AD9254 Rev. A evaluation board.
SCLK/DFS
If the SPI port is in external pin mode, the SCLK/DFS pin sets the data format of the outputs. If the pin is left floating, the pin is internally pulled down, setting the default condition to binary. Connecting JP2 Pin 2 and Pin 3 sets the format to twos complement. If the SPI port is in serial pin mode, connecting JP2 Pin 1 and Pin 2 connects the SCLK pin to the on-board SPI circuitry (see the Serial Port Interface (SPI) section).
POWER
Connect the switching power supply that is supplied in the evaluation kit between a rated 100 V ac to 240 V ac wall outlet at 47 Hz to 63 Hz and P500.
SDIO/DCS
If the SPI port is in external pin mode, the SDIO/DCS pin acts to set the duty cycle stabilizer. If the pin is left floating, the pin is internally pulled up, setting the default condition to DCS enabled. To disable the DCS, connect JP3 Pin 2 and Pin 3. If the SPI port is in serial pin mode, connecting JP3 Pin 1 and Pin 2 connects the SDIO pin to the on-board SPI circuitry (see the Serial Port Interface (SPI) section).
VIN
The evaluation board is set up for a double balun configuration analog input with optimum 50 impedance matching out to 70 MHz. For more bandwidth response, the differential capacitor across the analog inputs can be changed or removed (see Table 8). The common mode of the analog inputs is developed from the center tap of the transformer via the CML pin of the ADC (see the Analog Input Considerations section). VREF VREF is set to 1.0 V by tying the SENSE pin to ground via JP507 (Pin 1 and Pin 2). This causes the ADC to operate in 2.0 V p-p full-scale range. A separate external reference option is also included on the evaluation board. Connect JP507 between Pin 2 and Pin 3, connect JP501, and provide an external reference at E500. Proper use of the VREF options is detailed in the Voltage Reference section. RBIAS RBIAS requires a 10 k resistor (R503) to ground and is used to set the ADC core bias current.
ALTERNATIVE CLOCK CONFIGURATIONS
A differential LVPECL clock can also be used to clock the ADC input using the AD9515 (U500). When using this drive option, the components listed in Table 16 need to be populated. Consult the AD9515 data sheet for further information. To configure the analog input to drive the AD9515 instead of the default transformer option, the following components need to be added, removed, and/or changed. 1. 2. 3. Remove R507, R508, C532, and C533 in the default clock path. Populate R505 with a 0 resistor and C531 in the default clock path. Populate R511, R512, R513, R515 to R524, U500, R580, R582, R583, R584, C536, C537, and R586.
CLOCK
The default clock input circuitry is derived from a simple transformer-coupled circuit using a high bandwidth 1:1 impedance ratio transformer (T503) that adds a very low amount of jitter to the clock path. The clock input is 50 terminated and ac-coupled to handle single-ended sine wave inputs. The transformer converts the single-ended input to a differential signal that is clipped before entering the ADC clock inputs.
If using an oscillator, two oscillator footprint options are also available (OSC500) to check the performance of the ADC. JP508 provides the user flexibility in using the enable pin, which is common on most oscillators. Populate OSC500, R575, R587, and R588 to use this option.
PDWN
To enable the power-down feature, connect JP506, shorting the PDWN pin to AVDD.
ALTERNATIVE ANALOG INPUT DRIVE CONFIGURATION
This section provides a brief description of the alternative analog input drive configuration using the AD8352. When using this particular drive option, some components need to be populated, as listed in Table 16. For more details on the AD8352 differential driver, including how it works and its optional pin settings, consult the AD8352 data sheet.
CSB
The CSB pin is internally pulled-up, setting the chip into external pin mode, to ignore the SDIO and SCLK information. To connect the control of the CSB pin to the SPI circuitry on the evaluation board, connect JP1 Pin 1 and Pin 2. To set the chip into serial pin mode, and enable the SPI information on the SDIO and SCLK pins, tie JP1 low (connect Pin 2 and Pin 3) in the always enabled mode.
Rev. 0 | Page 27 of 40
AD9254
To configure the analog input to drive the AD8352 instead of the default transformer option, the following components need to be added, removed, and/or changed: 1. 2. 3. Remove C1 and C2 in the default analog input path. Populate R3 and R4 with 200 resistors in the analog input path. Populate the optional amplifier input path with all components except R594, R595, and C502. 4. Note that to terminate the input path, only one of the following components should be populated: R9, R592, or the combination of R590 and R591). Populate C529 with a 5 pF capacitor in the analog input path.
Currently, R561 and R562 are populated with 0 resistors to allow signal connection. This area allows the user to design a filter if additional requirements are necessary.
Rev. 0 | Page 28 of 40
SCHEMATICS
DOUBLE BALUN / XFMR INPUT
C1 .1UF C528 0.1UF
RC040 2
AMPOUT+
R561 0
RC0402 RC0402
R566 33
S500
RC0402 RC0402
VIN+
RC0402
SMAEDGE
R560 0
1
T500 T501
CC0402
2
R2 0
5 4
RC040 2
1 S 3 3 ETC1-1-13 4
C2 .1UF R1 DNI
RC0402
R3 25 R571 0
RC0402
Ain
P 2
R4 25 R562 0 C510 .1UF CML
RC0603
2 S P
R565 DNI R574 DNI
1
5
GND;3,4,5
RC0402
R563 DNI
CC0402
C529 20PF R567 33
RC0402
R502 50 DNI
ETC1-1-13
S503
C3 DNI CML
RC0402
SMAEDGE 3 4
CC0402
R7 DNI 2 5 R5 0
RC0402
RC060 3
VIN-
T502 DNI CML
RC0402
AMPOUT-
R6 DNI 1 6
1
C509 .1UF
2
VIN+
VIND501 DNI
Ain/
RC0603
When using R1, remove R3, R4,R6. Replace R5 with 0.1UF cap Replace C1, C2 with 0 ohm resistors.
GND;3,4,5
3
HSMS281 2
D500 DNI
3
When using T502, remove T500, T501. Repalce C1, C2 with 0 ohm resistors. Remove R3, R4. Place R6, R502,.
R594 10K DNI AMPVDD J500 C4 0 DNI R593 0 DNI C500 .1UF DNI
1
OPTIONAL AMP INPUT
1
2
DUTAVDD
HSMS281 2
R8 DNI
1
2
DUTAVDD
RC060 3
disable
3
DNI
GND;3,4,5 1 RDP 2
CC0402
Ampin/
RC0603
CC0402
Figure 53. Evaluation Board Schematic, DUT Analog Inputs
AMPVDD enable
2
Rev. 0 | Page 29 of 40
2
RC0603
S504
SMA200UP
R10 0 DNI
R595 10K DNI
C502 .1UF DNI
Ampin
R591 25 DNI R592 DNI C501 0.3PF R597 4.3K DNI DNI
1
16 VIP
15 ENB
14 VCM
13 VCC GND 12 11 VOP U511 VON 4 RDN VIN 10 9 GND GND 5 6 R596 0 DNI 7 VCC 8 AD8352 DNI SIGNAL=GND;17 RGP R598 100 RGN DNI 3
R535
0
DNI
RC0402
R9 DNI
AMPOUT+
C504 .1UF DNI
5
T1
1 S 3
R590 25 DNI
RC060 3
4
DNI
C5 0 DNI
P
2
R536
0
DNI
RC0402
AMPOUTC505 .1UF DNI
S505
2
SMA200UP
R12 0 DNI
1
DNI
GND;3,4,5
C503 .1UF DNI
AMPVDD
R11 0 DNI
RC060 3
06216-057
For amplifier (AD8352): Install all optional Amp input components. R590/R591,R9,R592 Only one should be installed at a time. Remove C1, C2. Set R3=R4=200 OHM.
AD9254
AD9254
DUT
24 23 22
CSB_DUT 2 SCLK_DTP 2 SDIO_ODM 2 1 3 1 JP3 JP2 3 DUTAVDD 1 JP1 3 DUTAVDD
SENSE
25
VREF
26 21 20 19 18 17 16 15
DOR TP503 TP501 D13 D12 DUTDRVDD
27
CC0402
C554 0.1UF
28
29
VIN+
30
VIN-
31
32
33 14 13
CML
34
35
C556 0.1UF
R503 10K
36 chip corners 12 11 10 9
D8 RP502 22 9 D13 11 RP502 22 12 RP502 22 4 RP502 22 14 RP502 22 2 RP502 22 16 RP501 22 RP501 22 RP501 22 4 RP501 22 14 RP501 22 2 RP501 22 16 RP500 22 5 RP500 22 6 7 RP500 22 3 2 1 4 15 3 5 6 11 12 13 1 15 3 13 5 6 RP502 22 8 DOR 10 7 RP502 22 D9 D10 D11
SENSE VREF REFB REFT AGND VIN+ VINAGND AVDD CML RBIAS PDWN
VDL
AVDD AGND AVDD AGND CSB SCLK/DFS SDIO/DCS DRVDD DRGND OR D13 (MSB) D12
CC0603
JP506 DNI
37
DUTAVDD
RC060 3
CLK
38 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 I6 GND7 I5 I4 VCC4 I3 I2 GND8 I1 I0 OE2 I7 I8 I9 GND6 I10 I11 VCC3 I12 O12 VCC2 O11 O10 GND3 O9 O8 O7 O6 GND2 O5 O4 VCC1 O3 O2 GND1 O1 O0 OE1 I13 O13 GND5 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
FD0 FIFOCLK FD2 FD1 FD4 FD3 FD8 FD7 FD6 FD5 FD10 FD9 FD12 FD11
CLK
39 OE3 24 23 22 I15 I14 O15 74VCX16224 OE4 O14 GND4 8 7 6
D7 D12 D6 D11 D5 D4 D10 D3 D2 TP502 D8 RP501 22 9 RP501 22 7 D5 D6 10 8 D7 D9
40
FIFOCLK FDOR FD13 FD13 FD12 FD11 FD10 FD9 FD8 FD7 FD6 FD5 FD4 FD3 FD2 FD1 FD0 FDOR
SDI_CHA
41
JP502 DNI
42
43 5 4 3 2 1
U509
TP504
DCO
44
CSB1_CHA
TP500
D0
45
D1
46
SDO_CHA
47
DUTDRVDD
48
D11 AGND D10 CLK+ EPAD D9 CLKD8 AVDD AGND DRVDD AVDD DRGND D7 OEB DCO D6 D0 (LSB) D5 U510 D1 D4 D3 DRGND D2 DRVDD AD9246LFCSP
Figure 54. Evaluation Board Schematic, DUT, VREF, and Digital Output Interface
3 2
JP500 SEN SE DNI R500 DNI
R0402
Rev. 0 | Page 30 of 40
JP507
SCLK_CHA
E500 D3
DUTAVDD
1
D4
JP501 D2 D1
E X T _V RE F
DNI
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16 A17 A18 A19 A20 J503
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 J503
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 J503
VREF D0 RP500 22 8 1 DCO R501
CC0805
R0402
OUTPUT CONNECTOR
CC0402
C555 0.1UF
C553 1.0UF DNI
OUTPUT BUFFER
06216-058
AVDD_3P3V R587
DISABLE RC0402
10K DNI 3
ENABLE RC0402
DNI JP508 1
XFMR/AD9515 Clock Circuitry
OSC500
14 VCC OE 1
DNI 0
2
AD9515 LOGIC SETUP
R588 10K DNI AVDD_3P3V R514 DNI
RC0603
R575 0 DNI
12 VCC OE GND GND 7 5 10 OUT 8 RC0402 CB3LV-3C OUT 3
R513
0
DNI
RC0603
S0 R525 DNI R506 0
CC0402
RC0603
0 R515
RC0603
0
C530 0.1UF R508 0 C533 0.1UF
DNI
RC0603
SMAEDGE S501
OPT_CLK
1
T503
RC0603
CLK
CLK
3
CC0402
6
S1
GND;3,4,5
2
D502 HSMS2812 R509 0 2 1
CC0402
RC0603
5
C532 0.1UF
R527 DNI
0 R517
RC0603
0 S2
DNI
RC0603
SMAEDGE S502
C531 0.1UF DNI R507 0 DNI
OPT_CLK
3
RC0603
4
CLK
CLK/
R512 0
RC060 3
CC0402
R526 DNI
0 R516
RC0603
0 S3 R531 DNI 0 R521
RC0603
DNI
RC0603
GND;3,4,5 C511 .1UF
R505 49.9 DNI
R504 49.9
0 S4 R530 DNI 0 R520
RC0603
DNI
RC0603
RC0402
RC0402
RC0402
CC0402
RC0402
CC0402
RC0402
R511 DNI
5 SYNCB
1
RC0603
2 AVDD_3P3V;1,4,17,20,21,24,26,29,30 NC=27,28
OUT1 S7 S8 S9 S10 OUT1B S0 S1 S2 S3 S4 S5 S6 19 18 RC0402 RC0402 VREF
RC0402
6
7
8
9
10
11
12
13
14
15
16
25
RC0402
R585 100 DNI
C534 0.1UF DNI
CC0402
C535 0.1UF DNI
06216-059
CC0402
Figure 55. Evaluation Board Schematic, DUT Clock Input
Rev. 0 | Page 31 of 40
AVDD_3P3V R576 DNI R581 DNI R580 10K DNI R586 4.12K DNI
RC0402
R510 DNI 1
RC0603
RC0402
RC060 3
RC060 3
To use AD9515 (OPT _CLK), remove R507, R508, C533, C532. Place C531,R505=0.
0 S5 R528 DNI 0 R518
RC0603
DNI
RC0603
0 S6
DNI
RC0603
C536 0.1UF DNI
R529 DNI
0 R519 0 DNI
CLK
RC0603
RC0603
S7 R534 DNI R582 100 DNI C537 0.1UF DNI 0 R524
RC0603
OPT_CLK
32 31 33
2 DNI U500
GN D OUT0 OUT0B 22 RSET 2 3 CLKB CLK 23 GND_PAD
0 S8
DNI
RC0603
R577 DNI AD9515
CLK
R533 DNI
0 R523
RC0603
0
DNI
RC0603
OPT_CLK
R579 DNI R578 DNI E501
R584 240 DNI
R583 240 DNI
S9 R532 DNI 0 R522
RC0603
0 S10 E502
DNI
RC0603
S0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10
E503
AD9254
AD9254
SDO_CHA
CSB1_CHA
SDI_CH A
SCLK_CHA
REMOVE WHEN USING OR PROGRAMMING PIC (U506)
RC0603 RC0603 RC0603 RC0603
SPI CIRCUITRY
1
A M PVD D R555 0 R554 0 R557 0 R556 0
+5V=PROGRAMMING ONLY=AMPVDD +3.3V=NORMAL OPERATION=AVDD_3P3V
JP509 3 DNI 2
A VD D _3 P3V
U506
1 2 GP5 GP4 SOIC8
RC0603
DNI VSS GP0 GP1 5
DNI R546 4.7K
RC0603
S1 VDD 7 6
DNI R545 4.7K DNI R547 4.7K
RC0603
DNI 8 3 4 MCLR GP2 PIC12F629 2
RC0603
1
3
DNI R558 4.7K
DUTAVDD AVDD_3P3V
RC0603 RC0603
RC060 3
C557 CC0603 0.1UF
DNI 1 2 DNI 1 R559 D505 261 Optional DNI
R551 1K
R553 1K
2
4
U508
E504
RC0603
GP0
GP1
MCLR-GP3 7 PICVCC 1
9
5
3
R550 10K
1 A1 2 GND 3 A2
6 Y1 5 VCC 4 Y2
PICVCC
R549 10K
RC0603
RC0603
Figure 56. Evaluation Board Schematic, SPI Circuitry
PIC-HEADER
Rev. 0 | Page 32 of 40
HEADER UP MALE
J504
DNI
AVDD_3P3V
NC7WZ07
R552 1K
RC0603
8 2
GP0 GP1
6
4
When using PICSPI controlled port, populate R545, R546, R547. When using PICSPI controlled port, remove R555, R556, R557. For FIFO controlled port, populate R555, R556, R557.
10
MCLR-GP3
SDIO_ODM
U507
SCLK_DTP
1 A1 2 GND 3 A2
R548 10K
6 Y1 5 VCC 4 Y2
CSB_DUT
NC7WZ16
06216-060
TP506 U502 ADP3339AKC-1.8 L504 10UH
4 LC1210 DUTAVDDIN
Power Supply Input 6V, 2A max
FER500 CHOKE_COIL 4
1
F500 3 PWR_IN PWR_IN IN P U T 3 2 OU TP UT1 OUTPUT4
D503 3A SHOT_RECT DO-214AB
DUTAVDD=1.8V DUTDRVDD=2.5V VDL=3.3V AMPVDD=5V AVDD_3.3V=3.3V
TP507 U501 ADP3339AKC-5 PWR_IN IN P U T 3 2
4
P500
SMDC110F
C527 10UF
1
CR500
GND
1
C519 1UF
C518 1UF
2
L501 10UH O UTP UT 1 OUTPUT4
LC1210 AMPVDDIN
2
3
D504 S2A_RECT 2A DO-214AA
U503 ADP3339AKC-2.5 L503 10UH
4 LC1210 DUTDRVDDIN
PWR_IN IN P U T
3
2 OU TP UT1 OUTPUT4
1
R589 261 TP505
GND
7.5V POWER CON005 2.5MM JACK
C523 1UF
C522 1UF
TP513 C520 1UF
PWR_IN
GND
C521 1UF
1
U505 ADP3339AKC-3.3 3 IN P U T 2 O UTP UT 1 OUTPUT4 4
L509 10UH
LC1210 AVDD_3P3V
OPTIONAL POWER CONNECTION
TP508 U504 ADP3339AKC-3.3 L508 10UH 4
LC1210 VDLIN PWR_IN
L505 10UH 3 IN P U T 2 OU TP UT1 OUTPUT4
P501 1 P1 AMPVDD
AMPVDDIN
LC1210
2 P2 C549 1OUF 6.3V C514 0.1UF
GND
3 P3
ACASE
J505
4 P4
GND
5 P5 VDL
DUTDRVDDIN
L507 10UH
6 P6
GND
LC1210
7 P7
ACASE
VDLIN C550 1OUF 6.3V C515 0.1UF AMPVDD AVDD_3P3V
8 P8
GND
9 P9
AVDD_3P3VIN
TP510
TP512
LC1210 CC0603
AVDD_3P3V C569 0.1UF
CC0603
TP511
TP509
Figure 57. Evaluation Board Schematic, Power Supply Inputs
C513 1UF DUTAVDD
CC0603 CC0603
Rev. 0 | Page 33 of 40
1
C567 0.1UF C568 0.1UF
CC0402 ACASE
DUTAVDDIN
10 P10
GND
L502 10UH
LC1210
GND
C524 1UF C526 1UF
C545 0.1UF
CC0402
C544 0.1UF
CC0402
1
GND
C525 1UF
C546 0.1UF
CC0402
C543 0.1UF
J502 VDL 0.1UF DUTDRVDD
CC0603 CC0603 CC0603 CC0603
C551 1OUF 6.3V C516 0.1UF
AVDD_3P3V
L506 10UH 0.1UF C559 C564 0.1UF C558 C565 0.1UF
LC1210
CC0402
C540 0.1UF
CC0402
C539 0.1UF
CC0402
C542 0.1UF
CC0402
C538 0.1UF
GROUND TEST POINTS
J501
ACASE
C552 1OUF 6.3V C517 0.1UF DUTAVDD
L500 10UH C575 0.1UF
H501
H502
CC0603
C566 0.1UF
CC0603
C570 0.1UF
CC0603
C574 0.1UF
H500
H503
ACASE
C548 1OUF 6.3V C512 0.1UF
Mounting Holes Connected to Ground
DUTDRVDD
CC0603
C573 0.1UF
CC0603
C572 0.1UF
CC0603
C599 0.1UF
To use optional power connection
Remove L501,L503,L504,L508,L509.
06216-061
AD9254
AD9254
EVALUATION BOARD LAYOUT
Figure 58. Evaluation Board Layout, Primary Side
Figure 59. Evaluation Board Layout, Secondary Side (Mirrored Image)
Rev. 0 | Page 34 of 40
06216-063
06216-062
AD9254
Figure 60. Evaluation Board Layout, Ground Plane
Figure 61. Evaluation Board Layout, Power Plane
Rev. 0 | Page 35 of 40
06216-065
06216-064
AD9254
Figure 62. Evaluation Board Layout, Silkscreen Primary Side
Figure 63. Evaluation Board Layout, Silkscreen Secondary Side (Mirrored Image)
Rev. 0 | Page 36 of 40
06216-067
06216-066
AD9254
BILL OF MATERIALS
Table 16. Evaluation Board Bill of Materials (BOM)
Item 1 2 Qty. 1 24 Omit (DNP) Reference Designator AD9246CE_REVA C1, C2, C509, C510, C511, C512, C514, C515, C516, C517, C528, C530, C532, C533, C538, C539, C540, C542, C543, C544, C545, C546, C554, C555 C3, C500, C502, C503, C504, C505, C531, C534, C535, C536, C537, C557 C501 C4, C5 C513, C518, C519, C520, C521, C522, C523, C524, C525, C526 C527 C529 C548, C549, C550, C551, C552 C553 C556, C558, C559, C564, C565, C566, C567, C568, C569, C570, C572, C573, C574, C575, C599 CR500 D502 D500, D501 D503 Device PCB Capacitor Package 0402 Description PCB 0.1 F Supplier/Part Number ADI
12
3 4 5 6 7 8 9 10
1 2 10 1 1 5 1 15
Capacitor Resistor Capacitor Capacitor Capacitor Capacitor Capacitor Capacitor
0402 0402 0402 1206 0402 ACASE 0805 0603
0.3 pF 0 1.0 F 10 F 20 pF 10 F 1.0 F 0.1 F
11 12 13
1 1 2 1
LED Diode Diode
0603 SOT-23 DO-214AB
green 30 V, 20 mA, dual Schottky 3 A, 30 V, SMC
Panasonic LNJ314G8TRA HSMS2812 Micro Commercial Components SK33TPMSCT-ND Micro Commercial Components S2ATPMSTR-ND Amber LED Tyco, Raychem NANOSMDC110F-2 Murata DLW5BSN191SQ2
14
1
D504
Diode
DO-214AA
2 A, 50 V, SMC
15 16
1 1
D505 F500
LED Fuse
LN1461C 1210
AMB 6.0 V, 2.2 A trip current resettable fuse
17 18 19 20 21 22 23 24 25
1 1 3 1 1 3 4 1 2 10
FER500 J500 J501, J502, J505 J503 J504 JP1, JP2, JP3 JP500, JP501, JP502, JP506 JP507 JP508, JP509 L500, L501, L502, L503, L504, L505, L506, L507, L508, L509 OSC500 P500
Choke Jumper Jumper Connector Connector Jumper Jumper Jumper Ferrite Bead
2020 Solder jumper Solder jumper Male header Male, 2 x 5 Male, straight Male, straight Male, straight
120 pin 10 pin 3 pin 2 pin 3-pin jumper 3.2 mm x 2.5 mm x 1.6 mm SMT PJ-102A
Samtec TSW-140-08-G-T-RA
Samtec Samtec TSW-103-07-G-S Samtec TSW-102-07-G-S Samtec TSW-103-07-G-S Digikey P9811CT-ND
26 27 1
1
Oscillator Connector
Rev. 0 | Page 37 of 40
125 MHz or 105 MHz DC power jack
CTS Reeves CB3LV-3C Digikey CP-102A-ND
AD9254
Item 28 29 30 31 32 33 34 35 36 Qty. Omit (DNP) 1 6 6 2 6 6 4 1 1 9 23 Reference Designator P501 R1, R6, R563, R565, R574, R577 R2, R5, R561, R562, R571 R10, R11, R12, R535, R536, R575 R3, R4 R7, R8, R9, R502, R510, R511 R500, R501, R576, R578, R579, R581 R503, R548, R549, R550 R504 R505 R506, R508, R509, R512, R554, R555, R556, R557, R560 R507, R513, R514, R515, R516, R517, R518, R519, R520, R521, R522, R523, R524, R525, R526, R527, R528, R529, R530, R531, R532, R533, R534, R545, R546, R547, R558 R551, R552, R553 R559 R566, R567 R582, R585, R598 R583, R584 R586 R580, R587, R588 R589 R590, R591 R592 R593, R596 R594, R595 R597 RP500 RP501, RP502 S1 Device Connector Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Package 10 pin 0402 0402 0402 0603 0402 0603 0603 0603 Description Male, straight DNI 0 25 DNI DNI 10 k 49.9 0 Supplier/Part Number PTMICRO10
5
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
4 3 1 2 3 2 1 3 1 2 1 2 2 1 1 2 1
Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Resistor Switch
0603 0603 0603 0402 0402 0402 0402 0402 0603 0402 0402 0402 0402 0402 RCA74204 RCA74208
54 55 56 57 58 59
2 2 2 2 1 1 1 1 1
S500, S501 S502, S503 S504, S505 T500, T501 T1 T503 T502 U500 U501
Connector Connector Transformer Transformer IC IC
SMAEDGE SMA200UP SM-22 CD542 32-pin LFCSP _VQ SOT-223
4.7 k 1 k 261 33 100 240 4.12 k 10 k 261 25 DNI 0 10 k 4.3 k 22 22 Momentary (normally open) SMA edge right angle SMA RF 5-pin upright
Panasonic EVQ-PLDA15
M/A-Com ETC1-1-13 Mini-Circuits ADT1-1WT Clock distribution Voltage regulator ADI AD9515BCPZ ADI ADP3339AKCZ-5
Rev. 0 | Page 38 of 40
AD9254
Item 60 61 62 63 64 65 66 67 68 Total 128 1 1 1 1 1 107 Qty. 1 1 2 1 Omit (DNP) Reference Designator U502 U503 U504, U505 U506 U507 U508 U509 U510 U511 (or Z500) Device IC IC IC IC IC IC IC DUT (AD9254) IC Package SOT-223 SOT-223 SOT-223 8-pin SOIC SC70 SC70 48-pin TSSOP 48-pin LFCSP_VQ 16-pin LFCSP_VQ Description Voltage regulator Voltage regulator Voltage regulator 8-bit microcontroller Dual buffer Dual buffer Buffer/line driver ADC Differential amplifier Supplier/Part Number ADI ADP3339AKCZ-1.8 ADI ADP3339AKCZ-2.5 ADI ADP3339AKCZ-3.3 Microchip PIC12F629 Fairchild NC7WZ16 Fairchild NC7WZ07 Fairchild 74VCX162244 ADI AD9254BCPZ ADI AD8352ACPZ
Rev. 0 | Page 39 of 40
AD9254 OUTLINE DIMENSIONS
7.00 BSC SQ 0.60 MAX 0.60 MAX
37 36
0.30 0.23 0.18
48 1
PIN 1 INDICATOR
PIN 1 INDICATOR
TOP VIEW
6.75 BSC SQ
EXPOSED PAD
(BOTTOM VIEW)
4.25 4.10 SQ 3.95
0.50 0.40 0.30
25 24
12 13
0.25 MIN 5.50 REF
1.00 0.85 0.80
12 MAX
0.80 MAX 0.65 TYP 0.05 MAX 0.02 NOM 0.50 BSC
SEATING PLANE
0.20 REF
COPLANARITY 0.08
COMPLIANT TO JEDEC STANDARDS MO-220-VKKD-2
Figure 64. 48-Lead Lead Frame Chip Scale Package [LFCSP_VQ] 7 mm x 7 mm Body, Very Thin Quad (CP-48-3) Dimensions shown in millimeters
ORDERING GUIDE
Model AD9254BCPZ-150 1, 2 AD9254BCPZRL7-1501, 2 AD9254-150EBZ1
1 2
Temperature Range -40C to +85C -40C to +85C
Package Description 48-Lead Lead Frame Chip Scale Package (LFCSP_VQ) 48-Lead Lead Frame Chip Scale Package (LFCSP_VQ) Evaluation Board
Package Option CP-48-3 CP-48-3
Z = Pb-free part. It is required that the exposed paddle be soldered to the AGND plane to achieve the best electrical and thermal performance.
(c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D06216-0-10/06(0)
Rev. 0 | Page 40 of 40

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