16-Bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS,
1.8 V Analog-to-Digital Converter
Data Sheet
AD9266
Rev. A
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Fax: 781.461.3113 ©2010–2012 Analog Devices, Inc. All rights reserved.
FEATURES
1.8 V analog supply operation
1.8 V to 3.3 V output supply
SNR
77.6 dBFS at 9.7 MHz input
71.1 dBFS at 200 MHz input
SFDR
93 dBc at 9.7 MHz input
80 dBc at 200 MHz input
Low power
56 mW at 20 MSPS
113 mW at 80 MSPS
Differential input with 700 MHz bandwidth
On-chip voltage reference and sample-and-hold circuit
2 V p-p differential analog input
DNL = −0.6/+1.1 LSB
Interleaved data output for reduced pin-count interface
Serial port control options
Offset binary, Gray code, or twos complement data format
Optional clock duty cycle stabilizer
Integer 1-to-8 input clock divider
Built-in selectable digital test pattern generation
Energy-saving power-down modes
Data clock output (DCO) with programmable clock and
data alignment
APPLICATIONS
Communications
Diversity radio systems
Multimode digital receivers
GSM, EDGE, W-CDMA, LT E, CDMA2000, WiMAX, TD-SCDMA
Smart antenna systems
Battery-powered instruments
Handheld scope meters
Portable medical imaging
Ultrasound
Radar/LIDAR
PET/SPECT imaging
FUNCTIONAL BLOCK DIAGRAM
VIN+
VIN–
VREF
SENSE
OR
D1_D0
D15_D14
8
DCO
SDIOAGND DRVDDAVDD SCLK
SPI
PROGRAMM ING DATA
VCM
RBIAS
PDWN DFSCLK+ CLK–
MODE
CONTROLS
DUTY CYCLE
STABILIZER
DIVIDE
1 TO 8
MODE
CSB
REF
SELECT
ADC
CORE
CMOS
OUTPUT BUFFER
AD9266
08678-001
Figure 1.
PRODUCT HIGHLIGHTS
1. The AD9266 operates from a single 1.8 V analog power
supply and features a separate digital output driver supply
to accommodate 1.8 V to 3.3 V logic families.
2. The patented sample-and-hold circuit maintains excellent
performance for input frequencies up to 200 MHz and is
designed for low cost, low power, and ease of use.
3. A standard serial port interface supports various product
features and functions, such as data output formatting,
internal clock divider, power-down, DCO and data output
(D15_D14 to D1_D0) timing and offset adjustments, and
voltage reference modes.
4. The AD9266 is packaged in a 32-lead RoHS-compliant
LFCSP that is pin compatible with the AD9609 10-bit
ADC, the AD9629 12-bit ADC, and the AD9649 14-bit
ADC, enabling a simple migration path between 10-bit and
16-bit converters sampling from 20 MSPS to 80 MSPS.
AD9266 Data Sheet
Rev. A | Page 2 of 32
TABLE OF CONTENTS
‘Features ............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
General Description ......................................................................... 3
Specifications ..................................................................................... 4
DC Specifications ......................................................................... 4
AC Specifications .......................................................................... 5
Digital Specifications ................................................................... 6
Switching Specifications .............................................................. 7
Timing Specifications .................................................................. 8
Absolute Maximum Ratings ............................................................ 9
Thermal Characteristics .............................................................. 9
ESD Caution .................................................................................. 9
Pin Configuration and Function Descriptions ........................... 10
Typical Performance Characteristics ........................................... 11
AD9266-80 .................................................................................. 11
AD9266-65 .................................................................................. 13
AD9266-40 .................................................................................. 14
AD9266-20 .................................................................................. 15
Equivalent Circuits ......................................................................... 16
Theory of Operation ...................................................................... 17
Analog Input Considerations .................................................... 17
Voltage Reference ....................................................................... 19
Clock Input Considerations ...................................................... 20
Power Dissipation and Standby Mode .................................... 22
Digital Outputs ........................................................................... 22
Timing ......................................................................................... 23
Output Test ...................................................................................... 24
Output Test Modes ..................................................................... 24
Serial Port Interface (SPI) .............................................................. 25
Configuration Using the SPI ..................................................... 25
Hardware Interface ..................................................................... 26
Configuration Without the SPI ................................................ 26
SPI Accessible Features .............................................................. 26
Memory Map .................................................................................. 27
Reading the Memory Map Register Table ............................... 27
Open Locations .......................................................................... 27
Default Values ............................................................................. 27
Memory Map Register Table ..................................................... 28
Memory Map Register Descriptions ........................................ 30
Applications Information .............................................................. 31
Design Guidelines ...................................................................... 31
Outline Dimensions ....................................................................... 32
Ordering Guide .......................................................................... 32
REVISION HISTORY
6/12—Rev. 0 to Rev. A
Changes to Table 1 ............................................................................. 4
Changes to Table 4 ............................................................................. 7
Changed Built-In Self-Test (BIST) and Output Test Section to
Output Test Section ......................................................................... 24
Changes to Output Test Section; Deleted Built-In Self-Test
(BIST) Section .................................................................................. 24
Changes to Table 16 ......................................................................... 28
04/10—Revision 0: Initial Version
Data Sheet AD9266
Rev. A | Page 3 of 32
GENERAL DESCRIPTION
The AD9266 is a monolithic, single-channel 1.8 V supply,
16-bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS analog-to-digital
converter (ADC). It features a high performance sample-and-
hold circuit and on-chip voltage reference.
The product uses multistage differential pipeline architecture
with output error correction logic to provide 16-bit accuracy at
80 MSPS data rates and to guarantee no missing codes over the
full operating temperature range.
The ADC contains several features designed to maximize
flexibility and minimize system cost, such as programmable
clock and data alignment and programmable digital test pattern
generation. The available digital test patterns include built-in
deterministic and pseudorandom patterns, along with custom
user-defined test patterns entered via the serial port interface (SPI).
A differential clock input with a selectable internal 1-to-8 divide
ratio controls all internal conversion cycles. An optional duty cycle
stabilizer (DCS) compensates for wide variations in the clock duty
cycle while maintaining excellent overall ADC performance.
The interleaved digital output data is presented in offset binary,
gray code, or twos complement format. A data output clock
(DCO) is provided to ensure proper latch timing with receiving
logic. Both 1.8 V and 3.3 V CMOS levels are supported.
The AD9266 is available in a 32-lead RoHS-compliant LFCSP
and is specified over the industrial temperature range (−40°C
to +85°C).
AD9266 Data Sheet
Rev. A | Page 4 of 32
SPECIFICATIONS
DC SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
Table 1.
Parameter Temp
AD9266-20/AD9266-40 AD9266-65 AD9266-80
Unit Min Typ Max Min Typ Max Min Typ Max
RESOLUTION Full 16 16 16 Bits
ACCURACY
No Missing Codes Full Guaranteed Guaranteed Guaranteed
Offset Error Full +0.05 ±0.30 +0.05 ±0.30 +0.05 ±0.30 % FSR
Gain Error1 Full −2.5/−2.0 −1.0 +1.0 % FSR
Differential Nonlinearity
(DNL)2
Full −0.9/+1.2 −0.9/+1.7 −0.9/+1.7 LSB
25°C −0.5/+0.6 −0.5/+1.0 −0.6/+1.1 LSB
Integral Nonlinearity
(INL)2
Full ±5.5 ±6.5 ±6.2 LSB
25°C ±1.8 ±2.4 ±3.5 LSB
TEMPERATURE DRIFT
Offset Error Full ±2 ±2 ±2 ppm/°C
INTERNAL VOLTAGE
REFERENCE
Output Voltage (1 V Mode) Full 0.983 0.995 1.007 0.983 0.995 1.007 0.983 0.995 1.007 V
Load Regulation Error
at 1.0 mA
Full 2 2 2 mV
INPUT-REFERRED NOISE
VREF = 1.0 V 25°C 2.8 2.8 2.8 LSB rms
ANALOG INPUT
Input Span, VREF = 1.0 V Full 2 2 2 V p-p
Input Capacitance3 Full 6.5 6.5 6.5 pF
Input Common-Mode
Voltage
Full 0.9 0.9 0.9 V
Input Common-Mode
Range
Full 0.5 1.3 0.5 1.3 0.5 1.3 V
REFERENCE INPUT
RESISTANCE
Full 7.5 7.5 7.5 kΩ
POWER SUPPLIES
Supply Voltage
AVDD Full 1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.9 V
DRVDD Full 1.7 3.6 1.7 3.6 1.7 3.6 V
Supply Current
IAVDD2 Full 31.4/40.7 33.2/42.5 54.5 57.6 62.5 65.7 mA
IDRVDD2 (1.8 V) Full 1.7/3.3 5.2 6.3 mA
IDRVDD2 (3.3 V) Full 3.0/5.9 9.3 11.6 mA
POWER CONSUMPTION
DC Input Full 57/73 98 113 mW
Sine Wave Input2
(DRVDD = 1.8 V)
Full 60/79 63/82 107 113 124 130 mW
Sine Wave Input2
(DRVDD = 3.3 V)
Full 66/93 129 151 mW
Standby Power
4
Full 40 44 44 mW
Power-Down Power Full 0.5 0.5 0.5 mW
1 Measured with 1.0 V external reference.
2 Measured with a 10 MHz input frequency at rated sample rate, full-scale sine wave, with approximately 5 pF loading on each output bit.
3 Input capacitance refers to the effective capacitance between the differential inputs.
4 Standby power is measured with a dc input and the CLK active.
Data Sheet AD9266
Rev. A | Page 5 of 32
AC SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
Table 2.
Parameter1 Temp
AD9266-20/AD9266-40 AD9266-65 AD9266-80
Unit Min Typ Max Min Typ Max Min Typ Max
SIGNAL-TO-NOISE RATIO (SNR)
fIN = 9.7 MHz 25°C 78.2 77.9 77.6 dBFS
fIN = 30.5 MHz 25°C 77.6 77.5 77.3 dBFS
Full 76.7 76.6 dBFS
fIN = 70 MHz 25°C 75.8/76.4 76.6 76.6 dBFS
Full 75.5 dBFS
fIN = 200 MHz 25°C 72.1 dBFS
SIGNAL-TO-NOISE-AND-DISTORTION (SINAD)
fIN = 9.7 MHz 25°C 78.0 77.7 77.4 dBFS
fIN = 30.5 MHz 25°C 77.5 77.3 77.1 dBFS
Full 76.2 76.2 dBFS
f
IN
= 70 MHz
25°C
75.7/76.3
76.5
76.6
dBFS
Full 75.5 dBFS
fIN = 200 MHz 25°C 69.4 dBFS
EFFECTIVE NUMBER OF BITS (ENOB)
fIN = 9.7 MHz 25°C 12.7 12.6 12.6 Bits
fIN = 30.5 MHz 25°C 12.6 12.5 12.5 Bits
fIN = 70 MHz 25°C 12.3/12.4 12.4 12.4 Bits
fIN = 200 MHz 25°C 11.2 Bits
WORST SECOND OR THIRD HARMONIC
fIN = 9.7 MHz 25°C −97 −96 −95 dBc
fIN = 30.5 MHz 25°C −96/−93 −94 −93 dBc
Full
−80
−80
dBc
fIN = 70 MHz 25°C −97/−95 −98 −95 dBc
Full −80 dBc
fIN = 200 MHz 25°C −80 dBc
SPURIOUS-FREE DYNAMIC RANGE (SFDR)
fIN = 9.7 MHz 25°C 95 95 94 dBc
fIN = 30.5 MHz 25°C 93 92 92 dBc
Full 80 80 dBc
fIN = 70 MHz 25°C 93 95 93 dBc
Full 80 dBc
fIN = 200 MHz 25°C 80 dBc
WORST OTHER (HARMONIC OR SPUR)
fIN = 9.7 MHz 25°C −102 −101 −99 dBc
fIN = 30.5 MHz 25°C −102 −101 −98 dBc
Full −89 −89 dBc
fIN = 70 MHz 25°C −101 −100 −98 dBc
Full −89 dBc
f
IN
= 200 MHz
25°C
−86
dBc
TWO-TONE SFDR
fIN = 30.5 MHz (−7 dBFS), 32.5 MHz (−7 dBFS) 25°C 90 90 90 dBc
ANALOG INPUT BANDWIDTH 25°C 700 700 700 MHz
1 See the AN-835 Application Note, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions.
AD9266 Data Sheet
Rev. A | Page 6 of 32
DIGITAL SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
Table 3.
Parameter Temp
AD9266-20/AD9266-40/AD9266-65/AD9266-80
Unit Min Typ Max
DIFFERENTIAL CLOCK INPUTS (CLK+, CLK−)
Logic Compliance CMOS/LVDS/LVPECL
Internal Common-Mode Bias Full 0.9 V
Differential Input Voltage Full 0.2 3.6 V p-p
Input Voltage Range Full GND − 0.3 AVDD + 0.2 V
High Level Input Current Full −10 +10 µA
Low Level Input Current Full −10 +10 µA
Input Resistance Full 8 10 12 kΩ
Input Capacitance Full 4 pF
LOGIC INPUTS (SCLK/DFS, MODE, SDIO/PDWN)1
High Level Input Voltage Full 1.2 DRVDD + 0.3 V
Low Level Input Voltage Full 0 0.8 V
High Level Input Current Full −50 −75 µA
Low Level Input Current Full −10 +10 µA
Input Resistance Full 30 kΩ
Input Capacitance Full 2 pF
LOGIC INPUTS (CSB)2
High Level Input Voltage Full 1.2 DRVDD + 0.3 V
Low Level Input Voltage Full 0 0.8 V
High Level Input Current Full −10 +10 µA
Low Level Input Current Full 40 135 µA
Input Resistance Full 26 kΩ
Input Capacitance
Full
2
pF
DIGITAL OUTPUTS
DRVDD = 3.3 V
High Level Output Voltage, I
OH
= 50 µA
Full
3.29
V
High Level Output Voltage, IOH = 0.5 mA Full 3.25 V
Low Level Output Voltage, IOL = 1.6 mA Full 0.2 V
Low Level Output Voltage, IOL = 50 µA Full 0.05 V
DRVDD = 1.8 V
High Level Output Voltage, IOH = 50 µA Full 1.79 V
High Level Output Voltage, IOH = 0.5 mA Full 1.75 V
Low Level Output Voltage, IOL = 1.6 mA Full 0.2 V
Low Level Output Voltage, IOL = 50 µA Full 0.05 V
1 Internal 30 kΩ pull-down.
2 Internal 30 kΩ pull-up.
Data Sheet AD9266
Rev. A | Page 7 of 32
SWITCHING SPECIFICATIONS
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
Table 4.
Parameter Temp
AD9266-20/AD9266-40 AD9266-65 AD9266-80
Unit Min Typ Max Min Typ Max Min Typ Max
CLOCK INPUT PARAMETERS
Input Clock Rate Full 80/320 520 625 MHz
Conversion Rate1 Full 3 20/40 3 65 3 80 MSPS
CLK Period—Divide-by-1 Mode (tCLK) Full 50/25 15.38 12.5 ns
CLK Pulse Width High (tCH) 25.0/12.5 7.69 6.25 ns
Aperture Delay (tA) Full 1.0 1.0 1.0 ns
Aperture Uncertainty (Jitter, tJ) Full 0.1 0.1 0.1 ps rms
DATA OUTPUT PARAMETERS
Data Propagation Delay (tPD) Full 1.84 3 3.90 1.84 3 3.90 1.84 3 3.90 ns
DCO Propagation Delay (tDCO) Full 1.86 3 4.04 1.86 3 4.04 1.86 3 4.04 ns
DCO to Data Skew (tSKEW) Full −0.53 0.1 0.72 −0.53 0.1 0.72 −0.53 0.1 0.72 ns
Pipeline Delay (Latency)
Full
9
9
9
Cycles
Wake-Up Time2 Full 350 350 350 µs
Standby Full 600/400 300 260 ns
OUT-OF-RANGE RECOVERY TIME Full 2 2 2 Cycles
1 Conversion rate is the clock rate after the CLK divider.
2 Wake-up time is dependent on the value of the decoupling capacitors.
08678-002
tCLK
tA
tDCO
tSKEW tSKEW
tPD
VIN
CLK+
CLK–
DCO
D1_D0
N – 1 NN + 1
N + 2 N + 3
N + 5
N + 6 N + 7
N + 8
D1
N–9
D0
N–9
D1
N–8
D0
N–8
D1
N–7
D0
N–7
D1
N–6
D0
N–6
D1
N–5
D0
N–5
D1
N–4
D0
N–4
D15
N–9
D14
N–9
D15
N–8
D14
N–8
D15
N–7
D14
N–7
D15
N–6
D14
N–6
D15
N–5
D14
N–5
D15
N–4
D14
N–4
D15_D14
Figure 2. CMOS Output Data Timing
AD9266 Data Sheet
Rev. A | Page 8 of 32
TIMING SPECIFICATIONS
Table 5.
Parameter Conditions Min Typ Max Unit
SPI TIMING REQUIREMENTS
tDS Setup time between the data and the rising edge of SCLK 2 ns
tDH Hold time between the data and the rising edge of SCLK 2 ns
tCLK Period of the SCLK 40 ns
t
S
Setup time between CSB and SCLK
2
ns
tH Hold time between CSB and SCLK 2 ns
tHIGH SCLK pulse width high 10 ns
tLOW SCLK pulse width low 10 ns
tEN_SDIO Time required for the SDIO pin to switch from an input to an output
relative to the SCLK falling edge
10 ns
tDIS_SDIO Time required for the SDIO pin to switch from an output to an input
relative to the SCLK rising edge
10 ns
Data Sheet AD9266
Rev. A | Page 9 of 32
ABSOLUTE MAXIMUM RATINGS
Table 6.
Parameter Rating
AVDD to AGND −0.3 V to +2.0 V
DRVDD to AGND −0.3 V to +3.9 V
VIN+, VIN− to AGND −0.3 V to AVDD + 0.2 V
CLK+, CLK− to AGND −0.3 V to AVDD + 0.2 V
VREF to AGND −0.3 V to AVDD + 0.2 V
SENSE to AGND −0.3 V to AVDD + 0.2 V
VCM to AGND −0.3 V to AVDD + 0.2 V
RBIAS to AGND −0.3 V to AVDD + 0.2 V
CSB to AGND −0.3 V to DRVDD + 0.3 V
SCLK/DFS to AGND −0.3 V to DRVDD + 0.3 V
SDIO/PDWN to AGND −0.3 V to DRVDD + 0.3 V
MODE/OR to AGND −0.3 V to DRVDD + 0.3 V
D1_D0 Through D15_D14 to AGND
−0.3 V to DRVDD + 0.3 V
DCO to AGND
−0.3 V to DRVDD + 0.3 V
Operating Temperature Range (Ambient) −40°C to +85°C
Maximum Junction Temperature Under Bias 150°C
Storage Temperature Range (Ambient) −65°C to +150°C
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 CHARACTERISTICS
The exposed paddle is the only ground connection for the chip.
The exposed paddle must be soldered to the AGND plane of the
user’s circuit board. Soldering the exposed paddle to the user’s
board also increases the reliability of the solder joints and
maximizes the thermal capability of the package.
Table 7. Thermal Resistance
Package
Type
Airflow
Velocity
(m/sec) θJA1, 2 θJC1, 3 θJB1, 4
Ψ
JT1, 2 Unit
32-Lead LFCSP
5 mm × 5 mm
0 37.1 3.1 20.7 0.3 °C/W
1.0 32.4 0.5 °C/W
2.5 29.1 0.8 °C/W
1 Per JEDEC 51-7, plus JEDEC 51-5 2S2P test board.
2 Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air).
3 Per MIL-Std 883, Method 1012.1.
4 Per JEDEC JESD51-8 (still air).
Typical θJA is specified for a 4-layer PCB with a solid ground
plane. As shown in Table 7, airflow improves heat dissipation,
which reduces θJA. In addition, metal in direct contact with the
package leads from metal traces, through holes, ground, and
power planes reduces the θJA.
ESD CAUTION
AD9266 Data Sheet
Rev. A | Page 10 of 32
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
NOTES
1. NC = NO CONNECT.
2. THE EXPOSED PADDLE (PIN 0) IS THE ONLY G ND
CONNE CTION O N THE CHI P AND M US T BE CONNECT E D
TO THE P CB AGND.
08678-003
CLK+
CLK–
AVDD
CSB
SCLK/DFS
SDIO/PDWN
NC
NC
AVDD
MODE/OR
DCO
(MS B) D15_D14
D13_D12
D11_D10
D9_D8
D7_D6
NC
NC
NC
NC
DRVDD
D1_D0 (L S B)
D3_D2
D5_D4
AVDD
VIN+
VIN–
AVDD
RBIAS
VCM
SENSE
VREF
TOP VIEW
(No t t o Scal e)
AD9266
24
23
22
21
20
19
18
17
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
32
31
30
29
28
27
26
25
Figure 3. Pin Configuration
Table 8. Pin Function Descriptions
Pin No. Mnemonic Description
0, Exposed Paddle AGND The exposed paddle is the only ground connection on the chip. It must be soldered to the analog
ground of the PCB to ensure proper functionality and heat dissipation, noise, and mechanical strength
benefits.
1, 2 CLK+, CLK− Differential Encode Clock for PECL, LVDS, or 1.8 V CMOS Inputs.
3, 24, 29, 32 AVDD 1.8 V Supply Pin for ADC Core Domain.
4 CSB SPI Chip Select. Active low enable, 30 kΩ internal pull-up.
5 SCLK/DFS SPI Clock Input in SPI Mode (SCLK). 30 kΩ internal pull-down.
Data Format Select in Non-SPI Mode (DFS). Static control of data output format. 30 kΩ internal pull-down.
DFS high = twos complement output; DFS low = offset binary output.
6 SDIO/PDWN SPI Data Input/Output (SDIO). Bidirectional SPI data I/O with 30 kΩ internal pull-down.
Non-SPI Mode Power-Down (PDWN). Static control of chip power-down with 30 kΩ internal pull-
down. See Table 14 for details.
7 to 12
NC
No Connect.
14 to 21 D1_D0 (LSB) to
(MSB) D15_D14
ADC Digital Outputs.
13 DRVDD 1.8 V to 3.3 V Supply Pin for Output Driver Domain.
22 DCO Data Clock Digital Output.
23 MODE/OR Chip Mode Select Input (MODE)/Out-of-Range Digital Output in SPI Mode (OR).
Default = out-of-range (OR) digital output (SPI Register 0x2A, Bit 0 = 1).
Option = chip mode select input (SPI Register 0x2A, Bit 0 = 0).
Chip power-down (SPI Register 0x08, Bits[7:5] = 100b).
Chip standby (SPI Register 0x08, Bits[7:5] = 101b).
Normal operation, output disabled (SPI Register 0x08, Bits[7:5] = 110b).
Normal operation, output enabled (SPI Register 0x08, Bits[7:5] = 111b).
Out-of-range (OR) digital output only in non-SPI mode.
25 VREF 1.0 V Voltage Reference Input/Output. See Table 10.
26 SENSE Reference Mode Selection. See Table 10.
27 VCM Analog Output Voltage at Mid AVDD Supply. Sets common mode of the analog inputs.
28 RBIAS Set Analog Current Bias. Connect to 10 kΩ (1% tolerance) resistor to ground.
30, 31 VIN−, VIN+ ADC Analog Inputs.
Data Sheet AD9266
Rev. A | Page 11 of 32
TYPICAL PERFORMANCE CHARACTERISTICS
AD9266-80
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
0
–140
–20
–40
–60
–80
–100
–120
0 5 10 15 20 25 30 35 40
AMPLITUDE (dBFS)
FREQUENCY (MHz)
80MSPS
9.7M Hz @ –1d BFS
SNR = 76. 8dB (77.8d BFS)
SF DR = 94.3d Bc
08678-033
Figure 4. AD9266-80 Single-Tone FFT with fIN = 9.7 MHz
0
–140
–20
–40
–60
–80
–100
–120
0 5 10 15 20 25 30 35 40
AMPLITUDE (dBFS)
FREQUENCY (MHz)
80MSPS
69MHz @ –1d BFS
SNR = 75. 1dB (76.1d BFS)
SF DR = 89.5d Bc
08678-035
Figure 5. AD9266-80 Single-Tone FFT with fIN = 69 MHz
0
–15
–30
–45
–60
–90
–75
–105
–120
–135 4 8 12 16 20 24 28 32 36
FREQUENCY (MHz)
AMPLITUDE (dBFS)
F2 – F1 F1 + F2 2F1 – F2
2F2 + F1
2F1 + F2
2F2 – F1
80MSPS
28.3M Hz @ –7d BFS
30.6M Hz @ –7d BFS
SF DR = 89.5d Bc ( 96.5d BFS)
08678-053
Figure 6. AD9266-80 Two-Tone FFT with fIN1 = 28.3 MHz and fIN2 = 30.6 MHz
0
–140
–20
–40
–60
–80
–100
–120
0 5 10 15 20 25 30 35 40
AMPLITUDE (dBFS)
FREQUENCY (MHz)
80MSPS
30.6M Hz @ –1d BFS
SNR = 76. 5dB (77.5d BFS)
SF DR = 85.7d Bc
08678-034
Figure 7. AD9266-80 Single-Tone FFT with fIN = 30.6 MHz
0
–140
–20
–40
–60
–80
–100
–120
0 5 10 15 20 25 30 35 40
AMPLITUDE (dBFS)
FREQUENCY (MHz)
80MSPS
210MHz @ –1d BFS
SNR = 70d B ( 71dBF S )
SF DR = 79.7d Bc
08678-036
Figure 8. AD9266-80 Single-Tone FFT with fIN = 210 MHz
10
–30
–10
–50
–70
–90
–110
–130
–95 –65–75–85 –55 –45 –35 –25 –15
INPUT AMPLITUDE (dBFS)
SF DR/IM D3 ( dBc/ dBFS )
SF DR ( dBc)
SF DR ( dBFS )
IM D3 ( dBc)
IM D3 ( dBFS )
08678-054
Figure 9. Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN) with fIN1 = 28.3 MHz
and fIN2 = 30.6 MHz
AD9266 Data Sheet
Rev. A | Page 12 of 32
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
100
90
80
70
60
50
40
30
20
10
0050 100 150 200
INP UT FRE QUENCY ( M Hz )
SNR/ S FDR (d BFS/dBc)
SF DR ( dBc)
SNR (dBFS )
08678-057
Figure 10. AD9266-80 SNR/SFDR vs. Input Frequency (AIN) with 2 V p-p Full Scale
100
90
80
70
30
40
50
60
20
10
010 20 30 40 50 60 70 80
SAMPLE RATE (MSPS)
SNR/ S FDR (d BFS/dBc)
SF DR ( dBc)
SNR (dBFS )
08678-055
Figure 11. AD9266-80 SNR/SFDR vs. Sample Rate with AIN = 9.7 MHz
120
0
20
40
60
80
100
–65 –60 0–10
–20–30–40–50 INPUT AMPLITUDE (dBFS)
SNR/ S FDR (d BFS/dBc)
SNR
SNRFS
SFDR
SFDRFS
08678-061
Figure 12. AD9266-80 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz
1.5
1.0
0.5
–0.5
0
–1.0
–1.5016,384 32,768 49,152 65,536
OUTPUT CODE
DNL E RROR (L S B)
08678-038
Figure 13. DNL Error with fIN = 9.7 MHz
0
6
4
2
–2
–4
–6016,384 32,768 49,152 65,536
OUTPUT CODE
INL ERRO R ( LSB)
08678-037
Figure 14. INL with fIN = 9.7 MHz
4.0M
0
500k
1.0M
1.5M
2.0M
2.5M
3.0M
3.5M
NUMBER OF HIT S
OUTPUT CODE
N + 10
N + 9
N + 8
N + 7
N + 6
N + 5
N + 4
N + 3
N + 2
N + 1
N
N – 1
N – 2
N – 3
N – 4
N – 5
N – 6
N – 7
N – 8
N – 9
N – 10
N – 11
N – 12
2.8 LSB RMS
08678-048
Figure 15. Grounded Input Histogram
Data Sheet AD9266
Rev. A | Page 13 of 32
AD9266-65
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
0
–140
–120
–100
–80
–60
–40
–20
030252015105
AMPLITUDE (dBFS)
FREQUENCY (MHz)
65MSPS
9.7M Hz @ –1d BFS
SNR = 76. 9dB (77.9d BFS)
SF DR = 95.9d Bc
08678-030
Figure 16. AD9266-65 Single-Tone FFT with fIN = 9.7 MHz
0
–140
–120
–100
–80
–60
–40
–20
030252015105
AMPLITUDE (dBFS)
FREQUENCY (MHz)
65MSPS
69MHz @ –1d BFS
SNR = 75. 5dB (76.5d BFS)
SF DR = 87.4d Bc
08678-032
Figure 17. AD9266-65 Single-Tone FFT with fIN = 69 MHz
0
–140
–120
–100
–80
–60
–40
–20
030252015105
AMPLITUDE (dBFS)
FREQUENCY (MHz)
65MSPS
30.6M Hz @ –1d BFS
SNR = 76. 6dB (77.6d BFS)
SF DR = 89.9d Bc
08678-031
Figure 18. AD9266-65 Single-Tone FFT with fIN = 30.6 MHz
120
0
20
40
60
80
100
–65 –60 0–10–20–30–40–50 INPUT AMPLITUDE (dBFS)
SNR/ S FDR (d BFS/dBc)
SNR
SNRFS
SFDR
SFDRFS
08678-060
Figure 19. AD9266-65 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz
100
90
80
70
60
50
40
30
20
10
0050 100 150 200
INP UT FRE QUENCY ( M Hz )
SNR/ S FDR (d BFS/dBc)
SF DR ( dBc)
SNR (dBFS )
08678-056
Figure 20. AD9266-65 SNR/SFDR vs. Input Frequency (AIN) with
2 V p-p Full Scale
AD9266 Data Sheet
Rev. A | Page 14 of 32
AD9266-40
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
0
–140
–120
–100
–80
–60
–40
–20
0 2 4 6 8 10 12 14 16 18 20
AMPLITUDE (dBFS)
FREQUENCY (MHz)
40MSPS
9.7M Hz @ –1d BFS
SNR = 76. 9dB (77.9d BFS)
SF DR = 95.1d Bc
08678-028
Figure 21. AD9266-40 Single-Tone FFT with fIN = 9.7 MHz
0
–140
–120
–100
–80
–60
–40
–20
0 2 4 6 8 10 12 14 16 18 20
AMPLITUDE (dBFS)
FREQUENCY (MHz)
40MSPS
30.6M Hz @ –1d BFS
SNR = 76. 6dB (77.6d BFS)
SF DR = 88.8d Bc
08678-029
Figure 22. AD9266-40 Single-Tone FFT with fIN = 30.6 MHz
120
0
20
40
60
80
100
–65 –60 0–10–20–30–40–50 INPUT AMPLITUDE (dBFS)
SNR/ S FDR (d BFS/dBc)
SNR
SNRFS
SFDR
SFDRFS
08678-059
Figure 23. AD9266-40 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz
Data Sheet AD9266
Rev. A | Page 15 of 32
AD9266-20
AVDD = 1.8 V; DRVDD = 1.8 V, maximum sample rate, 2 V p-p differential input, 1.0 V internal reference; AIN = −1.0 dBFS, 50% duty
cycle clock, DCS disabled, unless otherwise noted.
0
–140
–120
–100
–80
–60
–40
–20
0 1 2 3 4 5 6 7 8 9 10
AMPLITUDE (dBFS)
FREQUENCY (MHz)
20MSPS
9.7M Hz @ –1d BFS
SNR = 76. 9dB (77.9d BFS)
SF DR = 95.6d Bc
08678-024
Figure 24. AD9266-20 Single-Tone FFT with fIN = 9.7 MHz
0
–140
–120
–100
–80
–60
–40
–20
0 1 2 3 4 5 6 7 8 9 10
AMPLITUDE (dBFS)
FREQUENCY (MHz)
20MSPS
30.6M Hz @ –1d BFS
SNR = 76. 7dB (77.7d BFS)
SF DR = 90.7d Bc
08678-026
Figure 25. AD9266-20 Single-Tone FFT with fIN = 30.6 MHz
120
100
80
60
40
20
0
–90 –80 –70 –60 –50 –40 –30 –20 –10 0
INPUT AMPLITUDE (dBFS)
SNR/ S FDR (d BFS/dBc)
SFDRFS
SNRFS
SF DR ( dBc)
SNR (dBc)
08678-058
Figure 26. AD9266-20 SNR/SFDR vs. Input Amplitude (AIN) with fIN = 9.7 MHz
AD9266 Data Sheet
Rev. A | Page 16 of 32
EQUIVALENT CIRCUITS
AVDD
VIN±
08678-039
Figure 27. Equivalent Analog Input Circuit
7.5kΩ
VREF 375Ω
AVDD
08678-047
Figure 28. Equivalent VREF Circuit
SENSE 375Ω
AVDD
08678-046
Figure 29. Equivalent SENSE Circuit
CLK+
CLK–
0.9V
15kΩ
5Ω
5Ω
15kΩ
AVDD
AVDD
08678-040
Figure 30. Equivalent Clock Input Circuit
DRVDD
D1_D0 TO D15_D14,
OR
08678-042
Figure 31. Equivalent D1_D0 to D15_D14 and OR Digital Output Circuit
350Ω
DRVDD
30kΩ
SCLK/DFS,
MODE,
SDIO/PDWN
08678-043
Figure 32. Equivalent SCLK/DFS, MODE, and SDIO/PDWN Input Circuit
30kΩ
CSB 350Ω
AVDD
DRVDD
08678-045
Figure 33. Equivalent CSB Input Circuit
RBIAS
AND VCM
375Ω
AVDD
08678-044
Figure 34. Equivalent RBIAS and VCM Circuit
Data Sheet AD9266
Rev. A | Page 17 of 32
THEORY OF OPERATION
The AD9266 architecture consists of a multistage, pipelined ADC.
Each stage provides sufficient overlap to correct for flash errors in
the preceding stage. The quantized outputs from each stage are
combined into a final 16-bit result in the digital correction logic.
The pipelined architecture permits the first stage to operate with
a new input sample, whereas the remaining stages operate with
preceding samples. Sampling occurs on the rising edge of the clock.
Each stage of the pipeline, excluding the last, consists of a low
resolution flash ADC connected to a switched-capacitor DAC
and an interstage residue amplifier (for example, a multiplying
digital-to-analog converter (MDAC)). The residue amplifier
magnifies the difference between the reconstructed DAC output
and the flash input for the next stage in the pipeline. One bit of
redundancy is used in each stage to facilitate digital correction
of flash errors. The last stage simply consists of a flash ADC.
The output staging block aligns the data, corrects errors, and
passes the data to the CMOS output buffers. The output buffers
are powered from a separate (DRVDD) supply, allowing adjust-
ment of the output voltage swing. During power-down, the
output buffers go into a high impedance state.
ANALOG INPUT CONSIDERATIONS
The analog input to the AD9266 is a differential switched-
capacitor circuit designed for processing differential input
signals. This circuit can support a wide common-mode range
while maintaining excellent performance. By using an input
common-mode voltage of midsupply, users can minimize
signal-dependent errors and achieve optimum performance.
S S
H
CPAR
CSAMPLE
CSAMPLE
CPAR
VIN–
H
S S
H
VIN+
H
08678-006
Figure 35. Switched-Capacitor Input Circuit
The clock signal alternately switches the input circuit between
sample-and-hold mode (see Figure 35). When the input circuit
is switched to sample mode, the signal source must be capable
of charging the sample capacitors and settling within one-half
of a clock cycle. A small resistor in series with each input can
help reduce the peak transient current injected from the output
stage of the driving source. In addition, low Q inductors or ferrite
beads can be placed on each leg of the input to reduce high differ-
ential capacitance at the analog inputs and, therefore, achieve
the maximum bandwidth of the ADC. Such use of low Q inductors
or ferrite beads is required when driving the converter front end at
high IF frequencies. Either a shunt capacitor or two single-ended
capacitors can be placed on the inputs to provide a matching
passive network. This ultimately creates a low-pass filter at the
input to limit unwanted broadband noise. See the AN-742
Application Note, the AN-827 Application Note, and the Analog
Dialogue article “Transformer-Coupled Front-End for Wideband
A/D Converters” (Volume 39, April 2005) for more information. In
general, the precise values depend on the application.
Input Common Mode
The analog inputs of the AD9266 are not internally dc-biased.
Therefore, in ac-coupled applications, the user must provide
a dc bias externally. Setting the device so that VCM = AVDD/2
is recommended for optimum performance, but the device can
function over a wider range with reasonable performance, as
shown in Figure 36.
100
95
90
85
80
75
70
65
600.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3
SNR/ S FDR (d BFS/dBc)
INPUT COMMON-MODE VOLT AGE (V)
SF DR ( dBc)
SNR (dBFS )
08678-049
Figure 36. SNR/SFDR vs. Input Common-Mode Voltage,
fIN = 32.5 MHz, fS = 80 MSPS
An on-board, common-mode voltage reference is included in
the design and is available from the VCM pin. The VCM pin
must be decoupled to ground by a 0.1 µF capacitor, as described
in the Applications Information section.
Differential Input Configurations
Optimum performance is achieved while driving the AD9266 in a
differential input configuration. For baseband applications, the
AD8138, ADA4937-2, and ADA4938-2 differential drivers provide
excellent performance and a flexible interface to the ADC.
The output common-mode voltage of the ADA4938-2 is easily
set with the VCM pin of the AD9266 (see Figure 37), and the
driver can be configured in a Sallen-Key filter topology to
provide band limiting of the input signal.
AVDD
VIN 76.8Ω
120Ω
0.1µF
33Ω
33Ω
10pF
200Ω
200Ω
90Ω
ADA4938-2
ADC
VIN–
VIN+ VCM
08678-007
Figure 37. Differential Input Configuration Using the ADA4938-2
AD9266 Data Sheet
Rev. A | Page 18 of 32
For baseband applications below ~10 MHz where SNR is a key
parameter, differential transformer coupling is the recommended
input configuration. An example is shown in Figure 38. To bias
the analog input, the VCM voltage can be connected to the
center tap of the secondary winding of the transformer.
2V p-p 49.9Ω
0.1µF
R
R
C
ADC
VCM
VIN+
VIN–
08678-008
Figure 38. Differential Transformer-Coupled Configuration
The signal characteristics must be considered when selecting
a transformer. Most RF transformers saturate at frequencies
below a few megahertz (MHz). Excessive signal power can also
cause core saturation, which leads to distortion.
At input frequencies in the second Nyquist zone and above, the
noise performance of most amplifiers is not adequate to achieve
the true SNR performance of the AD9266. For applications above
~10 MHz where SNR is a key parameter, differential double balun
coupling is the recommended input configuration (see Figure 40).
An alternative to using a transformer-coupled input at frequencies
in the second Nyquist zone is to use the AD8352 differential driver.
An example is shown in Figure 41. See the AD8352 data sheet
for more information.
In any configuration, the value of Shunt Capacitor C is dependent
on the input frequency and source impedance and may need to
be reduced or removed. Tabl e 9 displays the suggested values to set
the RC network. However, these values are dependent on the
input signal and should be used only as a starting guide.
Table 9. Example RC Network
Frequency Range (MHz)
R Series
(Ω Each) C Differential (pF)
0 to 70 33 22
70 to 200 125 Open
Single-Ended Input Configuration
A single-ended input can provide adequate performance in
cost-sensitive applications. In this configuration, SFDR and
distortion performance degrade due to the large input common-
mode swing. If the source impedances on each input are matched,
there should be little effect on SNR performance. Figure 39
shows a typical single-ended input configuration.
1V p-p
R
R
C
49.9Ω 0.1µF
10µF
10µF0.1µF
AVDD
1kΩ
1kΩ
1kΩ
1kΩ
ADC
AVDD
VIN+
VIN–
08678-009
Figure 39. Single-Ended Input Configuration
ADC
R0.1µF
0.1µF
2V p-p
VCM
C
R
0.1µF
S0.1µF
25Ω
25Ω
SP
A
P
VIN+
VIN–
08678-010
Figure 40. Differential Double Balun Input Configuration
AD8352
0Ω
0Ω
CDRDRG
0.1µF
0.1µF
0.1µF
0.1µF
16
1
2
3
4
5
11
0.1µF
0.1µF
10
14
0.1µF
8, 13
V
CC
200Ω
200Ω
ANALOG INPUT
ANALOG INPUT
R
R
C
ADC
VCM
VIN+
VIN–
08678-011
Figure 41. Differential Input Configuration Using the AD8352
Data Sheet AD9266
Rev. A | Page 19 of 32
VOLTAGE REFERENCE
A stable and accurate 1.0 V voltage reference is built into the
AD9266. The VREF can be configured using either the internal
1.0 V reference or an externally applied 1.0 V reference voltage.
The various reference modes are summarized in the sections that
follow. The Reference Decoupling section describes the best
practices for PCB layout of VREF.
Internal Reference Connection
A comparator within the AD9266 detects the potential at the
SENSE pin and configures the reference into two possible modes,
which are summarized in Table 10. If SENSE is grounded, the
reference amplifier switch is connected to the internal resistor
divider (see Figure 42), setting VREF to 1.0 V.
VREF
SENSE
0.5V
ADC
SELECT
LOGIC
0.1µF1.0µF
VIN–
VIN+
ADC
CORE
08678-012
Figure 42. Internal Reference Configuration
If the internal reference of the AD9266 is used to drive multiple
converters to improve gain matching, the loading of the reference
by the other converters must be considered. Figure 43 shows
how the internal reference voltage is affected by loading.
0
–3.0 02.0
LOAD CURRENT ( mA)
REF E RE NCE V OLTAG E E RROR (%)
–0.5
–1.0
–1.5
–2.0
–2.5
0.2 0.4 0.6 0.8 1.0 1.4 1.6 1.81.2
INTERNAL V
REF
= 0.995V
08678-014
Figure 43. VREF Accuracy vs. Load Current
External Reference Operation
The use of an external reference may be necessary to enhance
the gain accuracy of the ADC or improve thermal drift charac-
teristics. Figure 44 shows the typical drift characteristics of the
internal reference in 1.0 V mode.
4
3
2
1
0
–1
–2
–3
–4
–5
–6
–40 –20 020 40 60 80
TEMPERATURE (°C)
VREF ERRO R ( mV )
VREF ERRO R ( mV )
08678-052
Figure 44. Typical VREF Drift
When the SENSE pin is tied to AVDD, the internal reference is
disabled, allowing the use of an external reference. An internal
reference buffer loads the external reference with an equivalent
7.5 kΩ load (see Figure 28). The internal buffer generates the posi-
tive and negative full-scale references for the ADC core. Therefore,
the external reference must be limited to a maximum of 1.0 V.
Table 10. Reference Configuration Summary
Selected Mode SENSE Voltage (V) Resulting VREF (V) Resulting Differential Span (V p-p)
Fixed Internal Reference AGND to 0.2 1.0 internal 2.0
Fixed External Reference AVDD 1.0 applied to external VREF pin 2.0
AD9266 Data Sheet
Rev. A | Page 20 of 32
CLOCK INPUT CONSIDERATIONS
For optimum performance, clock the AD9266 sample clock inputs,
CLK+ and CLK−, with a differential signal. The signal is typically
ac-coupled into the CLK+ and CLK− pins via a transformer or
capacitors. These pins are biased internally (see Figure 45) and
require no external bias.
0.9V
AVDD
2pF 2pF
CLK–CLK+
08678-016
Figure 45. Equivalent Clock Input Circuit
Clock Input Options
The AD9266 has a very flexible clock input structure. The clock
input can be a CMOS, LVDS, LVPECL, or sine wave signal.
Regardless of the type of signal being used, clock source jitter is
of great concern, as described in the Jitter Considerations section.
Figure 46 and Figure 47 show two preferred methods for clock-
ing the AD9266 (at clock rates up to 625 MHz when using the
internal clock divider). A low jitter clock source is converted from
a single-ended signal to a differential signal using either an RF
transformer or an RF balun.
0.1µF
0.1µF
0.1µF0.1µF
SCHOTTKY
DIODES:
HSMS2822
CLOCK
INPUT 50Ω 100Ω
CLK–
CLK+
ADC
Mini-Circuits
®
ADT1-1WT , 1:1 Z
XFMR
08678-017
Figure 46. Transformer-Coupled Differential Clock (Up to 200 MHz)
0.1µF
0.1µF1nF
CLOCK
INPUT
1nF
50Ω
CLK–
CLK+
SCHOTTKY
DIODES:
HSMS2822
ADC
08678-018
Figure 47. Balun-Coupled Differential Clock (Up to 625 MHz)
The RF balun configuration is recommended for clock frequencies
between 125 MHz and 625 MHz, and the RF transformer is recom-
mended for clock frequencies from 10 MHz to 200 MHz.
The back-to-back Schottky diodes across the transformer/
balun secondary limit clock excursions into the AD9266 to
approximately 0.8 V p-p differential.
This limit helps prevent the large voltage swings of the clock
from feeding through to other portions of the AD9266 while
preserving the fast rise and fall times of the signal that are
critical to a low jitter performance.
If a low jitter clock source is not available, another option is to
ac couple a differential PECL signal to the sample clock input
pins, as shown in Figure 48. The AD9510/AD9511/AD9512/
AD9513/AD9514/AD9515/AD9516/AD9517 clock drivers offer
excellent jitter performance.
100Ω
0.1µF
0.1µF
0.1µF
0.1µF
240Ω240Ω
50kΩ 50kΩ
CLK–
CLK+
CLOCK
INPUT
CLOCK
INPUT
ADC
AD951x
PECL DRIVER
08678-019
Figure 48. Differential PECL Sample Clock (Up to 625 MHz)
A third option is to ac couple a differential LVDS signal to the
sample clock input pins, as shown in Figure 49. The AD9510/
AD9511/AD9512/AD9513/AD9514/AD9515/AD9516/AD9517
clock drivers offer excellent jitter performance.
100Ω
0.1µF
0.1µF
0.1µF
0.1µF
50kΩ 50kΩ
CLK–
CLK+
ADC
CLOCK
INPUT
CLOCK
INPUT
AD951x
LVDS DRIVER
08678-020
Figure 49. Differential LVDS Sample Clock (Up to 625 MHz)
In some applications, it may be acceptable to drive the sample
clock inputs with a single-ended 1.8 V CMOS signal. In such
applications, drive the CLK+ pin directly from a CMOS gate, and
bypass the CLK− pin to ground with a 0.1 μF capacitor (see
Figure 50).
OPTIONAL
100Ω 0.1µF
0.1µF
0.1µF
50Ω
1
1
50Ω RESISTOR IS OPTIONAL.
CLK–
CLK+
ADC
V
CC
1kΩ
1kΩ
CLOCK
INPUT
AD951x
CMOS DRIVER
08678-021
Figure 50. Single-Ended 1.8 V CMOS Input Clock (Up to 200 MHz)
Data Sheet AD9266
Rev. A | Page 21 of 32
Input Clock Divider
The AD9266 contains an input clock divider with the ability
to divide the input clock by integer values between 1 and 8.
Optimum performance can be obtained by enabling the internal
duty cycle stabilizer (DCS) when using divide ratios other than
1, 2, or 4.
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 AD9266 contains a duty cycle stabilizer (DCS) that retimes
the nonsampling (falling) edge, providing an internal clock
signal with a nominal 50% duty cycle. This allows the user to
provide a wide range of clock input duty cycles without affecting
the performance of the AD9266. Noise and distortion perform-
ance are nearly flat for a wide range of duty cycles with the DCS on,
as shown in Figure 51.
80
79
78
77
76
70
71
72
73
74
75
30 35 40 45 50 55 60 65 70
SNR (dBFS )
POSIT I VE DUTY CYCLE (%)
DCS O FF
DCS O N
08678-064
Figure 51. SNR vs. DCS On/Off
Jitter in the rising edge of the input is still of concern and is not
easily reduced by the internal stabilization circuit. The duty
cycle control loop does not function for clock rates less than
20 MHz nominally. The loop has a time constant associated
with it that must be considered in applications in which the
clock rate can change dynamically. A wait time of 1.5 µs to 5 µs
is required after a dynamic clock frequency increase or decrease
before the DCS loop is relocked to the input signal.
Jitter Considerations
High speed, high resolution ADCs are sensitive to the quality of
the clock input. The degradation in SNR from the low frequency
SNR (SNRLF) at a given input frequency (fINPUT) due to jitter
(tJRMS) can be calculated by
SNRHF = −10 log[(2π × fINPUT × tJRMS)2 + 10
)10/( LF
SNR−
]
In the previous equation, the rms aperture jitter represents the
clock input jitter specification. IF undersampling applications
are particularly sensitive to jitter, as illustrated in Figure 52.
80
75
70
65
60
55
50
45110 100 1k
FREQUENCY (MHz)
SNR (dBFS )
0.5ps
0.2ps
0.05ps
1.0ps
1.5ps
2.0ps
2.5ps
3.0ps
08678-022
Figure 52. SNR vs. Input Frequency and Jitter
The clock input should be treated as an analog signal when
aperture jitter may affect the dynamic range of the AD9266. To
avoid modulating the clock signal with digital noise, keep power
supplies for clock drivers separate from the ADC output driver
supplies. Low jitter, crystal-controlled oscillators make the best
clock sources. If the clock is generated from another type of source
(by gating, dividing, or another method), it should be retimed by
the original clock at the last step.
For more information, see the AN-501 Application Note and
the AN-756 Application Note available at www.analog.com.
AD9266 Data Sheet
Rev. A | Page 22 of 32
POWER DISSIPATION AND STANDBY MODE
As shown in Figure 53, the analog core power dissipated by the
AD9266 is proportional to its sample rate. The digital power
dissipation of the CMOS outputs are determined primarily by
the strength of the digital drivers and the load on each output bit.
The maximum DRVDD current (IDRVDD) can be calculated as
IDRVDD = VDRVDD × CLOAD × fCLK × N
where N is the number of output bits (nine, in the case of the
AD9266).
This maximum current occurs when every output bit switches
on every clock cycle, that is, a full-scale square wave at the Nyquist
frequency of fCLK/2. In practice, the DRVDD current is estab-
lished by the average number of output bits switching, which
is determined by the sample rate and the characteristics of the
analog input signal.
Reducing the capacitive load presented to the output drivers can
minimize digital power consumption. The data in Figure 53 was
taken using the same operating conditions as those used for the
Typical Performance Characteristics, with a 5 pF load on each
output driver.
08678-067
45
55
65
75
85
95
105
115
10 20 30 40 50 60 70 80
ANALOG CORE P OWE R ( mW)
CLOCK RATE (MSPS)
AD9266-80
AD9266-65
AD9266-40
AD9266-20
Figure 53. Analog Core Power vs. Clock Rate
In SPI mode, the AD9266 can be placed in power-down mode
directly via the SPI port, or by using the programmable external
MODE pin. In non-SPI mode, power-down is achieved by assert-
ing the PDWN pin high. In this state, the ADC typically dissipates
500 µW. D u r i n g p o w e r -down, the output drivers are placed in
a high impedance state. Asserting PDWN low (or the MODE pin
in SPI mode) returns the AD9266 to its normal operating mode.
Note that PDWN is referenced to the digital output driver
supply (DRVDD) and should not exceed that supply voltage.
Low power dissipation in power-down mode is achieved by
shutting down the reference, reference buffer, biasing networks,
and clock. Internal capacitors are discharged when entering power-
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.
When using the SPI port interface, the user can place the ADC
in power-down mode or standby mode. Standby mode allows
the user to keep the internal reference circuitry powered when
faster wake-up times are required. See the Memory Map section
for more details.
DIGITAL OUTPUTS
The AD9266 output drivers can be configured to interface with
1.8 V to 3.3 V CMOS logic families. Output data can also be
multiplexed onto a single output bus to reduce the total number
of traces required.
The CMOS output drivers are sized to provide sufficient output
current to drive a wide variety of logic families. However, large
drive currents tend to cause current glitches on the supplies and
may affect converter performance.
Applications requiring the ADC to drive large capacitive loads
or large fanouts may require external buffers or latches.
The output data format can be selected to be either offset binary
or twos complement by setting the SCLK/DFS pin when operating
in the external pin mode (see Table 11).
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.
Table 11. SCLK/DFS and SDIO/PDWN Mode Selection
(External Pin Mode)
Voltage at Pin SCLK/DFS SDIO/PDWN
AGND Offset binary (default) Normal operation
(default)
DRVDD Twos complement Outputs disabled
Digital Output Enable Function (OEB)
When using the SPI interface, the data outputs and DCO can be
independently three-stated by using the programmable external
MODE pin. The MODE pin (OEB) function is enabled via Bits[6:5]
of Register 0x08.
If the MODE pin is configured to operate in traditional OEB
mode and the MODE pin is low, the output data drivers and
DCOs are enabled. If the MODE pin is high, the output data
drivers and DCOs are placed in a high impedance state. This
OEB function is not intended for rapid access to the data bus.
Note that the MODE pin is referenced to the digital output
driver supply (DRVDD) and should not exceed that supply
voltage.
Data Sheet AD9266
Rev. A | Page 23 of 32
TIMING
The AD9266 provides latched data with a pipeline delay of
eight clock cycles. Data outputs are available one propagation
delay (tPD) after the rising edge of the clock signal.
Minimize the length of the output data lines and loads placed
on them to reduce transients within the AD9266. These
transients can degrade converter dynamic performance.
The lowest typical conversion rate of the AD9266 is 3 MSPS. At
clock rates below 3 MSPS, dynamic performance may degrade.
Data Clock Output (DCO)
The AD9266 provides a data clock output (DCO) signal that is
intended for capturing the data in an external register. The CMOS
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.
Table 12. Output Data Format
Input (V) Condition (V) Offset Binary Output Mode Twos Complement Mode OR
VIN+ − VIN− < −VREF − 0.5 LSB 0000 0000 0000 0000 1000 0000 0000 0000 1
VIN+ − VIN− = −VREF 0000 0000 0000 0000 1000 0000 0000 0000 0
VIN+ − VIN−
= 0
1000 0000 0000 0000
0000 0000 0000 0000
0
VIN+ − VIN− = +VREF − 1.0 LSB 1111 1111 1111 1111 0111 1111 1111 1111 0
VIN+ − VIN− > +VREF − 0.5 LSB 1111 1111 1111 1111 0111 1111 1111 1111 1
AD9266 Data Sheet
Rev. A | Page 24 of 32
OUTPUT TEST
The AD9266 includes various output test options to place
predictable values on the outputs of the AD9266.
OUTPUT TEST MODES
The output test options are described in Tabl e 16 at Address 0x0D.
When an output test mode is enabled, the analog section of the
ADC is disconnected from the digital back end blocks and the
test pattern is run through the output formatting block. Some of
the test patterns are subject to output formatting, and some are
not. The PN generators from the PN sequence tests can be reset
by setting Bit 4 or Bit 5 of Register 0x0D. These tests can be
performed with or without an analog signal (if present, the analog
signal is ignored), but they do require an encode clock. For more
information, see the AN-877 Application Note, Interfacing to
High Speed ADCs via SPI.
Data Sheet AD9266
Rev. A | Page 25 of 32
SERIAL PORT INTERFACE (SPI)
The AD9266 serial port interface (SPI) allows the user to con-
figure the converter for specific functions or operations through
a structured register space provided inside the ADC. The SPI gives
the user added flexibility and customization, depending on the
application. Addresses are accessed via the serial port and can
be written to or read from via the port. Memory is organized
into bytes that can be further divided into fields, which are
documented in the Memory Map section. For more detailed
operational information, see the AN-877 Application Note,
Interfacing to High Speed ADCs via SPI.
CONFIGURATION USING THE SPI
Three pins define the SPI of this ADC: SCLK, SDIO, and CSB
(see Table 13). The SCLK (a serial clock) is used to synchronize
the read and write data presented from and to the ADC. SDIO
(serial data input/output) is a dual-purpose pin that allows data to
be sent and read from the internal ADC memory map registers.
The CSB (chip select bar) is an active-low control that enables
or disables the read and write cycles.
Table 13. Serial Port Interface Pins
Pin Function
SCLK Serial clock. The serial shift clock input, which is used to
synchronize serial interface reads and writes.
SDIO
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.
CSB Chip select bar. An active-low control that gates the read
and write cycles.
The falling edge of CSB, in conjunction with the rising edge of
SCLK, determines the start of the framing. An example of the
serial timing and its definitions can be found in Figure 54 and
Table 5.
Other modes involving the CSB pin are available. CSB can be
held low indefinitely, which permanently enables the device;
this is called streaming. CSB can stall high between bytes to
allow for additional external timing. When CSB is tied high,
SPI functions are placed in high impedance mode. This mode
turns on any SPI pin secondary functions.
During an instruction phase, a 16-bit instruction is transmitted.
Data follows the instruction phase, and its length is determined
by the W0 and W1 bits, as shown in Figure 54.
All data is composed of 8-bit words. The first bit of the first byte in
a multibyte serial data transfer frame indicates whether a read
command or a write command is issued. This allows the serial
data input/output (SDIO) pin to change direction from an input
to an output at the appropriate point in the serial frame.
In addition to word length, the instruction phase determines
whether the serial frame is a read or write operation, allowing
the serial port to be used both to program the chip and to read
the contents of the on-chip memory. If the instruction is a readback
operation, performing a readback causes the serial data input/
output (SDIO) pin to change direction from an input to an output
at the appropriate point in the serial frame.
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.
DON’ T CARE
DON’ T CAREDON’ T CARE
DON’ T CARE
SDIO
SCLK
CSB
tStDH
tCLK
tDS tH
R/W W1 W0 A12 A11 A10 A9 A8 A7 D5 D4 D3 D2 D1 D0
tLOW
tHIGH
08678-023
Figure 54. Serial Port Interface Timing Diagram
AD9266 Data Sheet
Rev. A | Page 26 of 32
HARDWARE INTERFACE
The pins described in Table 13 constitute the physical interface
between the programming device of the user and the serial port
of the AD9266. The SCLK pin and the CSB pin function as inputs
when using the SPI interface. The SDIO pin is bidirectional,
functioning as an input during write phases and as an output
during readback.
The SPI interface is flexible enough to be controlled by either
FPGAs or microcontrollers. One method for SPI configuration
is described in detail in the AN-812 Application Note, Micro-
controller-Based Serial Port Interface (SPI) Boot Circuit.
The SPI port should not be active during periods when the full
dynamic performance of the converter is required. Because the
SCLK signal, the CSB signal, and the SDIO signal are typically
asynchronous to the ADC clock, noise from these signals can
degrade converter performance. If the on-board SPI bus is used for
other devices, it may be necessary to provide buffers between
this bus and the AD9266 to prevent these signals from transi-
tioning at the converter inputs during critical sampling periods.
SDIO/PDWN and SCLK/DFS serve a dual function when the
SPI interface is not being used. When the pins are strapped to
DRVDD or ground during device power-on, they are associated
with a specific function. The Digital Outputs section describes
the strappable functions supported on the AD9266.
CONFIGURATION WITHOUT THE SPI
In applications that do not interface to the SPI control registers,
the SDIO/PDWN pin and the SCLK/DFS pin serve as standalone
CMOS-compatible control pins. When the device is powered up, it
is assumed that the user intends to use the pins as static control
lines for the power-down and output data format feature control.
In this mode, connect the CSB chip select to DRVDD, which
disables the serial port interface.
Table 14. Mode Selection
Pin
External
Voltage Configuration
SDIO/PDWN DRVDD Chip power-down mode
AGND (default) Normal operation (default)
SCLK/DFS DRVDD Twos complement enabled
AGND (default) Offset binary enabled
SPI ACCESSIBLE FEATURES
Table 15 provides a brief description of the general features that
are accessible via the SPI. These features are described in detail
in the AN-877 Application Note, Interfacing to High Speed ADCs
via SPI. The AD9266 part-specific features are described in
detail in Table 16.
Table 15. Features Accessible Using the SPI
Feature Description
Modes
Allows the user to set either power-down mode
or standby mode
Clock Allows the user to access the DCS via the SPI
Offset Allows the user to digitally adjust the converter
offset
Test I/O
Allows the user to set test modes to have known
data on output bits
Output Mode Allows the user to set up outputs
Output Phase Allows the user to set the output clock polarity
Output Delay Allows the user to vary the DCO delay
Data Sheet AD9266
Rev. A | Page 27 of 32
MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Each row in the memory map register table (see Table 16)
contains eight bit locations. The memory map is roughly
divided into four sections: the chip configuration registers
(Address 0x00 to Address 0x02); the device index and transfer
register (Address 0xFF); the program registers, including setup,
control, and test (Address 0x08 to Address 0x2A); and the
AD9266-specific customer SPI control register (Address 0x101).
Table 16 documents the default hexadecimal value for each hexa-
decimal address shown. The column with the heading Bit 7 (MSB)
is the start of the default hexadecimal value given. For example,
Address 0x2A, the OR/MODE select register, has a hexadecimal
default value of 0x01. This means that in Address 0x2A,
Bits[7:1] = 0, and Bit 0 = 1. This setting is the default OR/MODE
setting. The default value results in the programmable external
MODE/OR pin (Pin 23) functioning as an out-of-range digital
output. For more information on this function and others, see the
AN-877 Application Note, Interfacing to High Speed ADCs via SPI.
This application note details the functions controlled by Register
0x00 to Register 0xFF. The remaining register, Register 0x101, is
documented in the Memory Map Register Descriptions section
that follows Table 16.
OPEN LOCATIONS
All address and bit locations that are not included in the SPI map
are not currently supported for this device. Unused bits of a valid
address location should be written with 0s. Writing to these loca-
tions is required only when part of an address location is open
(for example, Address 0x2A). If the entire address location is
open, it is omitted from the SPI map (for example, Address 0x13)
and should not be written.
DEFAULT VALUES
After the AD9266 is reset, critical registers are loaded with
default values. The default values for the registers are given in
the memory map register table (see Table 16).
Logic Levels
An explanation of logic level terminology follows:
• “Bit is set” is synonymous with “bit is set to Logic 1” or
“writing Logic 1 for the bit.”
• “Clear a bit” is synonymous with “bit is set to Logic 0” or
“writing Logic 0 for the bit.”
Transfer Register Map
Address 0x08 to Address 0x18 are shadowed. Writes to these
addresses do not affect part operation until a transfer command
is issued by writing 0x01 to Address 0xFF, setting the transfer bit.
This allows these registers to be updated internally and simulta-
neously when the transfer bit is set. The internal update takes
place when the transfer bit is set, and then the bit autoclears.
AD9266 Data Sheet
Rev. A | Page 28 of 32
MEMORY MAP REGISTER TABLE
All address and bit locations that are not included in Table 16 are not currently supported for this device.
Table 16.
Addr
(Hex) Register Name
Bit 7
(MSB) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
Bit 0
(LSB)
Default
Value
(Hex) Comments
Chip Configuration Registers
0x00 SPI port
configuration
0 LSB
first
Soft
reset
1 1 Soft
reset
LSB first 0 0x18 The nibbles are
mirrored so that
LSB- or MSB-first
mode registers
correctly, regardless
of shift mode.
0x01
Chip ID
8-bit chip ID, Bits[7:0]
AD9266 = 0x78
Read
only
Unique chip ID
used to differentiate
devices; read only.
0x02 Chip grade Open Speed grade ID, Bits[6:4] (identify
device variants of chip ID)
20 MSPS = 000
40 MSPS = 001
65 MSPS = 010
80 MSPS = 011
Open Read
only
Unique speed
grade ID used
to differentiate
devices; read only.
Device Index and Transfer Register
0xFF Transfer Open Transfer 0x00 Synchronously
transfers data from
the master shift
register to the slave.
Program Registers
0x08 Modes External
Pin 23 mode
input enable
External Pin 23
function when high
00 = full power-
down
01 = standby
10 = normal mode:
output disabled
11 = normal mode:
output enabled
Open 00 = chip run
01 = full power-down
10 = standby
11 = chip wide digital
reset
0x00 Determines various
generic modes of
chip operation.
0x09 Clock Open Duty cycle
stabilize
0x01 Enable internal
duty cycle stabilizer
(DCS).
0x0B Clock divide Open Clock divider, Bits[2:0]
Clock divide ratio:
000 = divide by 1
001 = divide by 2
010 = divide by 3
011 = divide by 4
100 = divide by 5
101 = divide by 6
110 = divide by 7
111 = divide by 8
0x00 The divide ratio is
the value plus 1.
0x0D Test mode User test mode
00 = single
01 = alternate
10 = single once
11 = alternate once
Reset PN
long gen
Reset PN
short gen
Output test mode, Bits[3:0] (local)
0000 = off (default)
0001 = midscale short
0010 = positive FS
0011 = negative FS
0100 = alternating checkerboard
0101 = PN 23 sequence
0110 = PN 9 sequence
0111 = 1/0 word toggle
1000 = user input
1001 = 1/0 bit toggle
1010 = 1× sync
1011 = one bit high
1100 = mixed bit frequency
0x00 When set, the test
data is placed on
the output pins in
place of normal data.
0x10 Offset adjust 8-bit device offset adjustment, Bits[7:0] (local)
Offset adjust in LSBs from +127 to −128 (twos complement format)
0x00 Device offset trim.
0x14 Output mode 00 = 3.3 V CMOS
10 = 1.8 V CMOS
Open Output
disable
Open Output
invert
00 = offset binary
01 = twos complement
10 = gray code
11 = offset binary
0x00 Configures the
outputs and the
format of the data.
Data Sheet AD9266
Rev. A | Page 29 of 32
Addr
(Hex) Register Name
Bit 7
(MSB) Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1
Bit 0
(LSB)
Default
Value
(Hex) Comments
0x15 Output adjust 3.3 V DCO
drive strength
00 = 1 stripe (default)
01 = 2 stripes
10 = 3 stripes
11 = 4 stripes
1.8 V DCO
drive strength
00 = 1 stripe
01 = 2 stripes
10 = 3 stripes (default)
11 = 4 stripes
3.3 V data
drive strength
00 = 1 stripe (default)
01 = 2 stripes
10 = 3 stripes
11 = 4 stripes
1.8 V data drive strength
00 = 1 stripe
01 = 2 stripes
10 = 3 stripes (default)
11 = 4 stripes
0x22 Determines CMOS
output drive
strength properties.
0x16 Output phase DCO output
polarity
0 = normal
1 = inverted
Open Input clock phase adjust, Bits[2:0]
(Value is number of input clock
cycles of phase delay)
000 = no delay
001 = 1 input clock cycle
010 = 2 input clock cycles
011 = 3 input clock cycles
100 = 4 input clock cycles
101 = 5 input clock cycles
110 = 6 input clock cycles
111 = 7 input clock cycles
0x00 On devices that use
global clock divide,
determines which
phase of the divider
output is used to
supply the output
clock; internal
latching is
unaffected.
0x17 Output delay Enable DCO
delay
Open Enable
data
delay
Open DCO/data delay[2:0] (typical values)
000 = 0.56 ns
001 = 1.12 ns
010 = 1.68 ns
011 = 2.24 ns
100 = 2.80 ns
101 = 3.36 ns
110 = 3.92 ns
111 = 4.48 ns
0x00 Sets the fine
output delay of the
output clock but
does not change
internal timing.
(Typical values)
0x19 USER_PATT1_LSB B7 B6 B5 B4 B3 B2 B1 B0 0x00 User-defined
pattern, 1 LSB.
0x1A USER_PATT1_MSB B15 B14 B13 B12 B11 B10 B9 B8 0x00 User-defined
pattern, 1 MSB.
0x1B USER_PATT2_LSB B7 B6 B5 B4 B3 B2 B1 B0 0x00 User-defined
pattern, 2 LSB.
0x1C USER_PATT2_MSB B15 B14 B13 B12 B11 B10 B9 B8 0x00 User-defined
pattern, 2 MSB.
0x2A OR/MODE select Open 0 = MODE
1 = OR
(default)
0x01 Selects I/O
functionality in
conjunction with
Address 0x08 for
MODE (input) or
OR (output) on
External Pin 23.
AD9266-Specific Customer SPI Control Register
0x10
1
USR2 Open Enable
GCLK
detect
Run
GCLK
Open Disable
SDIO pull-
down
0x08 Enables internal
oscillator for clock
rates of <5 MHz.
AD9266 Data Sheet
Rev. A | Page 30 of 32
MEMORY MAP REGISTER DESCRIPTIONS
For additional information about functions that are controlled
in Register 0x00 to Register 0xFF, see the AN-877 Application
Note, Interfacing to High Speed ADCs via SPI at www.analog.com.
USR2 (Register 0x101)
Bit 3—Enable GCLK Detect
Normally set high, this bit enables a circuit that detects encode
rates below about 5 MSPS. When a low encode rate is detected,
an internal oscillator, GCLK, is enabled, ensuring the proper
operation of several circuits. If set low, the detector is disabled.
Bit 2—Run GCLK
This bit enables the GCLK oscillator. For some applications
with encode rates below 10 MSPS, it may be preferable to set
this bit high to supersede the GCLK detector.
Bit 0—Disable SDIO Pull-Down
This bit can be set high to disable the internal 30 kΩ pull-down
on the SDIO pin, which can be used to limit the loading when
many devices are connected to the SPI bus.
Data Sheet AD9266
Rev. A | Page 31 of 32
APPLICATIONS INFORMATION
DESIGN GUIDELINES
Before starting design and layout of the AD9266 as a system,
it is recommended that the designer become familiar with these
guidelines, which discuss the special circuit connections and
layout requirements needed for certain pins.
Power and Ground Recommendations
When connecting power to the AD9266, it is strongly recom-
mended that two separate supplies be used. Use one 1.8 V supply
for analog (AVDD); use a separate 1.8 V to 3.3 V supply for the
digital output supply (DRVDD). If a common 1.8 V AVDD and
DRVDD supply must be used, the AVDD and DRVDD domains
must be isolated with a ferrite bead or filter choke and separate
decoupling capacitors. Several different decoupling capacitors
can be used to cover both high and low frequencies. Locate
these capacitors close to the point of entry at the PCB level
and close to the pins of the part, with minimal trace length.
A single PCB ground plane should be sufficient when using the
AD9266. With proper decoupling and smart partitioning of the
PCB analog, digital, and clock sections, optimum performance
is easily achieved.
Exposed Paddle Thermal Heat Sink Recommendations
The exposed paddle (Pin 0) is the only ground connection for
the AD9266; therefore, it must be connected to analog ground
(AGND) on the customer’s PCB. To achieve the best electrical
and thermal performance, mate an exposed (no solder mask)
continuous copper plane on the PCB to the AD9266 exposed
paddle, Pin 0.
The copper plane should have several vias to achieve the
lowest possible resistive thermal path for heat dissipation to
flow through the bottom of the PCB. Fill or plug these vias
with nonconductive epoxy.
To maximize the coverage and adhesion between the ADC and
the PCB, a silkscreen should be overlaid to partition the continuous
plane on the PCB into several uniform sections. This provides
several tie points between the ADC and the PCB during the reflow
process. Using one continuous plane with no partitions guarantees
only one tie point between the ADC and the PCB. For detailed
information about packaging and PCB layout of chip scale
packages, see the AN-772 Application Note, A Design and
Manufacturing Guide for the Lead Frame Chip Scale Package
(LFCSP) at www.analog.com.
Encode Clock
For optimum dynamic performance, a low jitter encode clock
source with a 50% duty cycle ± 5% should be used to clock the
AD9266.
VCM
The VCM pin should be decoupled to ground with a 0.1 μF
capacitor, as shown in Figure 38.
RBIAS
The AD9266 requires that a 10 kΩ resistor be placed between
the RBIAS pin and ground. This resistor sets the master current
reference of the ADC core and should have at least a 1% tolerance.
Reference Decoupling
Externally decouple the VREF pin to ground with a low ESR,
1.0 μF capacitor in parallel with a low ESR, 0.1 μF ceramic
capacitor.
SPI Port
The SPI port should not be active during periods when the full
dynamic performance of the converter is required. Because the
SCLK, CSB, and SDIO signals are typically asynchronous to the
ADC clock, noise from these signals can degrade converter
performance. If the on-board SPI bus is used for other devices,
it may be necessary to provide buffers between this bus and the
AD9266 to keep these signals from transitioning at the converter
inputs during critical sampling periods.
AD9266 Data Sheet
Rev. A | Page 32 of 32
OUTLINE DIMENSIONS
08-16-2010-B
1
0.50
BSC
BOTTOM VIEWTOP VIEW
PIN 1
INDICATOR
32
9
16
17
2425
8
EXPOSED
PAD
PIN 1
INDICATOR
SEATING
PLANE
0.05 MAX
0.02 NOM
0.20 REF
COPLANARITY
0.08
0.30
0.25
0.18
5.10
5.00 SQ
4.90
0.80
0.75
0.70
FOR PROPER CONNECTION OF
THE EXPOSED PAD, REFER TO
THE PIN CONFIGURATION AND
FUNCTION DESCRIPTIONS
SECTION OF THIS DATA SHEET.
0.50
0.40
0.30
0.25 MIN
*3.75
3.60 SQ
3.55
*COMPLIANT TO JEDEC STANDARDS MO-220-WHHD-5
WITH EXCEPTION TO EXPOSED PAD DIMENSION.
Figure 55. 32-Lead Lead Frame Chip Scale Package [LFCSP_WQ]
5 mm × 5 mm Body, Very Very Thin Quad (CP-32-12)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
AD9266BCPZ-80 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266BCPZRL7-80 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266BCPZ-65 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266BCPZRL7-65 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266BCPZ-40
–40°C to +85°C
32-Lead Lead Frame Chip Scale Package (LFCSP_WQ)
CP-32-12
AD9266BCPZRL7-40 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266BCPZ-20 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266BCPZRL7-20 –40°C to +85°C 32-Lead Lead Frame Chip Scale Package (LFCSP_WQ) CP-32-12
AD9266-80EBZ Evaluation Board
AD9266-65EBZ Evaluation Board
AD9266-40EBZ
Evaluation Board
AD9266-20EBZ Evaluation Board
1 Z = RoHS Compliant Part.
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Analog Devices Inc.:
AD9266-20EBZ AD9266-40EBZ AD9266-65EBZ AD9266-80EBZ AD9266BCPZ-65 AD9266BCPZ-20
AD9266BCPZ-80 AD9266TCPZ-65EP AD9266BCPZ-40 AD9266BCPZRL7-65 AD9266BCPZRL7-20
AD9266BCPZRL7-80 AD9266TCPZRL7-65EP AD9266BCPZRL7-40
