16-Bit, 125 MSPS/105 MSPS/80 MSPS,
1.8 V Analog-to-Digital Converter
AD9265
Data Sheet
FEATURES
PRODUCT HIGHLIGHTS
SNR = 79.0 dBFS at 70 MHz and 125 MSPS
SFDR = 93 dBc at 70 MHz and 125 MSPS
Low power: 373 mW at 125 MSPS
1.8 V analog supply operation
1.8 V CMOS or LVDS output supply
Integer 1-to-8 input clock divider
IF sampling frequencies to 300 MHz
−154.3 dBm/Hz small signal input noise with 200 Ω input
impedance at 70 MHz and 125 MSPS
Optional on-chip dither
Programmable internal ADC voltage reference
Integrated ADC sample-and-hold inputs
Flexible analog input range: 1 V p-p to 2 V p-p
Differential analog inputs with 650 MHz bandwidth
ADC clock duty cycle stabilizer
Serial port control
User-configurable, built-in self-test (BIST) capability
Energy-saving power-down modes
1.
On-chip dither option for improved SFDR performance
with low power analog input.
Proprietary differential input that maintains excellent SNR
performance for input frequencies up to 300 MHz.
Operation from a single 1.8 V supply and a separate digital
output driver supply accommodating 1.8 V CMOS or
LVDS outputs.
Standard serial port interface (SPI) that supports various
product features and functions, such as data formatting
(offset binary, twos complement, or gray coding), enabling
the clock duty cycle stabilizer, DCS, power-down, test
modes, and voltage reference mode.
Pin compatibility with the AD9255, allowing a simple
migration from 16 bits down to 14 bits.
2.
3.
4.
5.
APPLICATIONS
Communications
Multimode digital receivers (3G)
GSM, EDGE, W-CDMA, LTE, CDMA2000, WiMAX,
and TD-SCDMA
Smart antenna systems
General-purpose software radios
Broadband data applications
Ultrasound equipment
FUNCTIONAL BLOCK DIAGRAM
SENSE RBIAS
VREF
PDWN
AGND
AVDD (1.8V)
REFERENCE
LVDS LVDS_RS
AD9265
VCM
VIN+
VIN–
DRVDD (1.8V)
TRACK-AND-HOLD
ADC
16-BIT
CORE
DITHER
CLK+
CLK–
SYNC
OUTPUT
STAGING 16
CMOS OR
LVDS
(DDR)
16
CLOCK
MANAGEMENT
D15 TO D0
OR
SERIAL PORT
SVDD SCLK/ SDIO/ CSB
DFS DCS
08502-001
DCO
Figure 1.
Rev. D
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AD9265
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Voltage Reference ...................................................................... 28
Applications ...................................................................................... 1
Clock Input Considerations ..................................................... 29
Product Highlights ........................................................................... 1
Power Dissipation and Standby Mode .................................... 31
Functional Block Diagram .............................................................. 1
Digital Outputs ........................................................................... 32
Revision History ............................................................................... 2
Timing ......................................................................................... 32
General Description ......................................................................... 3
Built-In Self-Test (BIST) and Output Test ................................. 33
Specifications .................................................................................... 4
Built-In Self-Test (BIST) ........................................................... 33
ADC DC Specifications ............................................................... 4
Output Test Modes .................................................................... 33
ADC AC Specifications ................................................................. 5
Serial Port Interface (SPI) ............................................................. 34
Digital Specifications ................................................................... 6
Configuration Using the SPI .................................................... 34
Switching Specifications ................................................................ 8
Hardware Interface .................................................................... 34
Timing Specifications .................................................................. 9
Configuration Without the SPI ................................................ 35
Absolute Maximum Ratings ......................................................... 10
SPI Accessible Features ............................................................. 35
Thermal Characteristics ............................................................ 10
Memory Map .................................................................................. 36
ESD Caution................................................................................ 10
Reading the Memory Map Register Table .............................. 36
Pin Configurations and Function Descriptions ......................... 11
Memory Map Register Table .................................................... 37
Typical Performance Characteristics ........................................... 15
Memory Map Register Descriptions ....................................... 39
Equivalent Circuits ......................................................................... 23
Applications Information ............................................................. 40
Theory of Operation ...................................................................... 25
Design Guidelines ...................................................................... 40
ADC Architecture ...................................................................... 25
Outline Dimensions ....................................................................... 41
Analog Input Considerations ................................................... 25
Ordering Guide .......................................................................... 41
REVISION HISTORY
11/2020—Rev. C to Rev. D
Changed CP-48-8 to CP-48-9 ...................................... Throughout
Changes to Figure 4........................................................................ 11
Changes to Figure 5........................................................................ 13
Updated Outline Dimensions ....................................................... 41
Changes to Ordering Guide .......................................................... 41
8/2013—Rev. B to Rev. C
Changes to Data Clock Output (DCO) Section ......................... 32
Changes to Ordering Guide .......................................................... 41
3/2013—Rev. A to Rev. B
Changes to Table 17 ....................................................................... 37
Updated Outline Dimensions ...................................................... 41
1/2010—Rev. 0 to Rev. A
Changes to Worst Other (Harmonic or Spur) Parameter,
Table 2 .................................................................................................5
Changes to Figure 77 ..................................................................... 29
Changes to Input Clock Divider Section .................................... 30
Changes to Table 17 ....................................................................... 37
Updated Outline Dimensions ...................................................... 41
10/2009—Revision 0: Initial Version
Rev. D | Page 2 of 44
Data Sheet
AD9265
GENERAL DESCRIPTION
The AD9265 is a 16-bit, 125 MSPS analog-to-digital converter
(ADC). The AD9265 is designed to support communications
applications where high performance combined with low cost,
small size, and versatility is desired.
The ADC core features a multistage, differential pipelined
architecture with integrated output error correction logic to
provide 16-bit accuracy at 125 MSPS data rates and guarantees
no missing codes over the full operating temperature range.
The ADC features a wide bandwidth differential sample-andhold analog input amplifier supporting a variety of user-selectable
input ranges. 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 AD9265 is suitable for applications in communications,
instrumentation and medical imaging.
A differential clock input controls all internal conversion cycles. A
duty cycle stabilizer provides the means to compensate for variations in the ADC clock duty cycle, allowing the converters to
maintain excellent performance over a wide range of input clock
duty cycles. An integrated voltage reference eases design considerations.
The ADC output data format is either parallel 1.8 V CMOS or
LVDS (DDR). A data output clock is provided to ensure proper
latch timing with receiving logic.
Programming for setup and control is accomplished using a 3-wire
SPI-compatible serial interface. Flexible power-down options
allow significant power savings, when desired. An optional onchip dither function is available to improve SFDR performance
with low power analog input signals.
The AD9265 is available in a Pb-free, 48-lead LFCSP and is specified over the industrial temperature range of −40°C to +85°C.
Rev. D | Page 3 of 44
AD9265
Data Sheet
SPECIFICATIONS
ADC DC SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 1.8 V, SVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference,
DCS enabled, unless otherwise noted.
Table 1.
Parameter
RESOLUTION
ACCURACY
No Missing Codes
Offset Error
Gain Error
Differential Nonlinearity (DNL)2
Integral Nonlinearity (INL)2
TEMPERATURE DRIFT
Offset Error
Gain Error
INTERNAL VOLTAGE REFERENCE
Output Voltage Error (1 V Mode)
Load Regulation at 1.0 mA
INPUT REFERRED NOISE
VREF = 1.0 V
ANALOG INPUT
Input Span, VREF = 1.0 V
Input Capacitance3
Input Common-Mode Voltage
REFERENCE INPUT RESISTANCE
POWER SUPPLIES
Supply Voltage
AVDD
DRVDD
SVDD
Supply Current
IAVDD2
IDRVDD2
1.8 V CMOS
1.8 V LVDS
POWER CONSUMPTION
DC Input
Sine Wave Input2
DRVDD = 1.8 V
CMOS Output Mode
LVDS Output Mode
Standby Power4
Power-Down Power
Temp
Full
AD9265BCPZ-801
Min
Typ
Max
16
AD9265BCPZ-1051
Min
Typ
Max
16
AD9265BCPZ-1251
Min
Typ
Max
16
Unit
Bits
Full
Full
Full
Full
25°C
Full
25°C
Guaranteed
±0.05
±0.25
±0.2
±2.5
−1.0
+1.25
±0.6
±2.5
±1.5
Guaranteed
±0.05
±0.25
±0.2
±2.5
−1.0
+1.25
±0.65
±3.5
±2.0
Guaranteed
±0.05
±0.25
±0.4
±2.5
−1.0
+1.25
±0.7
±4.5
±3.0
% FSR
% FSR
LSB
LSB
LSB
LSB
Full
Full
±2
±15
Full
Full
+8
3
25°C
2.17
2.26
2.17
LSB rms
Full
Full
Full
Full
2
8
0.9
6
2
8
0.9
6
2
8
0.9
6
V p-p
pF
V
kΩ
±12
1.8
1.8
1.9
1.9
3.5
Full
126
131
Full
Full
14
43
Full
241
Full
Full
Full
Full
254
308
54
0.05
Full
Full
Full
1.7
1.7
1.7
±2
±15
+8
3
1.7
1.7
1.7
±2
±15
±12
1.8
1.8
1.9
1.9
3.5
169
176
20
46
258
323
0.15
341
391
54
0.05
1
The suffix following the part number refers to the model found in the Ordering Guide section.
Measured with a low input frequency, full-scale sine wave, with approximately 5 pF loading on each output bit.
3
Input capacitance refers to the effective capacitance between one differential input pin and AGND.
4
Standby power is measured with a dc input, the CLK pins (CLK+, CLK−) inactive (set to AVDD or AGND).
2
Rev. D | Page 4 of 44
+8
3
1.7
1.7
1.7
ppm/°C
ppm/°C
±12
mV
mV
1.8
1.8
1.9
1.9
3.5
V
V
V
194
202
mA
24
49
343
373
0.15
394
439
54
0.05
mA
mA
392
mW
.015
mW
mW
mW
mW
Data Sheet
AD9265
ADC AC SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 1.8 V, SVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference,
DCS enabled, unless otherwise noted.
Table 2.
1
Parameter
SIGNAL-TO-NOISE-RATIO (SNR)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
SIGNAL-TO-NOISE-AND DISTORTION (SINAD)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
EFFECTIVE NUMBER OF BITS (ENOB)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
WORST SECOND OR THIRD HARMONIC
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
SPURIOUS-FREE DYNAMIC RANGE (SFDR)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
SPURIOUS-FREE DYNAMIC RANGE (SFDR)
Without Dither (AIN at −23 dBFS)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
With On-Chip Dither (AIN at −23 dBFS)
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
Temp
25°C
25°C
Full
25°C
25°C
25°C
25°C
Full
25°C
25°C
AD9265BCPZ-802
Min
Typ
Max
AD9265BCPZ-1052
Min
Typ
Max
80.2
79.7
79.7
79.2
78.7
AD9265BCPZ-1252
Min
Typ
Max
79.0
79.0
78.2
dBFS
dBFS
dBFS
dBFS
dBFS
77.3
78.4
77.1
78.3
76.9
77.5
75.6
79.6
79.6
79.4
78.8
78.7
78.7
Unit
77.3
76.0
77.5
75.7
77.0
74.4
dBFS
dBFS
dBFS
dBFS
dBFS
25°C
25°C
25°C
25°C
12.9
12.9
12.5
12.3
12.9
12.8
12.6
12.3
12.8
12.8
12.5
12.1
Bits
Bits
Bits
Bits
25°C
25°C
Full
25°C
25°C
−88
−94
−90
−89
−88
−93
−82
−81
−86
−81
−89
−80
dBc
dBc
dBc
dBc
dBc
25°C
25°C
Full
25°C
25°C
88
94
90
89
88
93
78.6
77.9
77.0
−92
−88
−85
82
81
86
81
89
80
dBc
dBc
dBc
dBc
dBc
25°C
25°C
25°C
25°C
103
103
104
102
98
96
96
101
96
98
98
97
dBFS
dBFS
dBFS
dBFS
25°C
25°C
25°C
25°C
110
110
110
110
108
109
109
109
108
110
109
109
dBFS
dBFS
dBFS
dBFS
92
88
Rev. D | Page 5 of 44
85
AD9265
1
Parameter
WORST OTHER (HARMONIC OR SPUR)
Without Dither
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
With On-Chip Dither
fIN = 2.4 MHz
fIN = 70 MHz
fIN = 140 MHz
fIN = 200 MHz
TWO-TONE SFDR
Without Dither
fIN = 29 MHz (−7 dBFS ), 32 MHz (−7 dBFS )
fIN = 169 MHz (−7 dBFS ), 172 MHz (−7 dBFS )
ANALOG INPUT BANDWIDTH
1
2
Data Sheet
AD9265BCPZ-802
Min
Typ
Max
AD9265BCPZ-1052
Min
Typ
Max
AD9265BCPZ-1252
Min
Typ
Max
25°C
25°C
Full
25°C
25°C
−106
−106
−105
−104
−101
−103
−104
−102
−103
−103
−104
−100
25°C
25°C
Full
25°C
25°C
−106
−106
−105
−105
−102
−103
−104
−101
−103
−101
25°C
25°C
25°C
93
80
650
90
78
650
Temp
−97
−92
dBc
dBc
dBc
dBc
dBc
−98
−104
−100
dBc
dBc
dBc
dBc
dBc
95
79
650
dBc
dBc
MHz
−95
−97
Unit
−99
See Application Note AN-835, Understanding High Speed ADC Testing and Evaluation, for a complete set of definitions.
The suffix following the part number refers to the model found in the Ordering Guide section.
DIGITAL SPECIFICATIONS
AVDD = 1.8 V, DRVDD = 1.8 V, SVDD = 1.8 V, maximum sample rate, VIN = −1.0 dBFS differential input, 1.0 V internal reference, and DCS
enabled, unless otherwise noted.
Table 3.
Parameter
DIFFERENTIAL CLOCK INPUTS (CLK+, CLK−)
Logic Compliance
Internal Common-Mode Bias
Differential Input Voltage
Input Voltage Range
Input Common-Mode Range
High Level Input Current
Low Level Input Current
Input Capacitance
Input Resistance
SYNC INPUT
Logic Compliance
Internal Bias
Input Voltage Range
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
Input Capacitance
Input Resistance
Temperature
Min
Full
Full
Full
Full
Full
Full
Full
Full
CMOS/LVDS/LVPECL
0.9
0.3
3.6
AGND
AVDD
0.9
1.4
−100
+100
−100
+100
4
8
10
12
Full
Full
Full
Full
Full
Full
Full
Full
Rev. D | Page 6 of 44
Typ
Max
CMOS
0.9
AGND
1.2
AGND
−100
−100
12
AVDD
AVDD
0.6
+100
+100
1
16
20
Unit
V
V p-p
V
V
μA
μA
pF
kΩ
V
V
V
V
μA
μA
pF
kΩ
Data Sheet
Parameter
LOGIC INPUT (CSB)1
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
Input Resistance
Input Capacitance
LOGIC INPUT (SCLK/DFS)2
High Level Input Voltage
Low Level Input Voltage
High Level Input Current (VIN = 1.8 V)
Low Level Input Current
Input Resistance
Input Capacitance
LOGIC INPUT/OUTPUT (SDIO/DCS)1
High Level Input Voltage
Low Level Input Voltage
High Level Input Current
Low Level Input Current
Input Resistance
Input Capacitance
High Level Output Voltage
Low Level Output Voltage
LOGIC INPUTS (OEB, PDWN, DITHER, LVDS, LVDS_RS)2
High Level Input Voltage
Low Level Input Voltage
High Level Input Current (VIN = 1.8 V)
Low Level Input Current
Input Resistance
Input Capacitance
DIGITAL OUTPUTS (DRVDD = 1.8 V)
CMOS Mode
High Level Output Voltage
IOH = 50 μA
IOH = 0.5 mA
Low Level Output Voltage
IOL = 1.6 mA
IOL = 50 μA
LVDS Mode
ANSI Mode
Differential Output Voltage (VOD)
Output Offset Voltage (VOS)
Reduced Swing Mode
Differential Output Voltage (VOD)
Output Offset Voltage (VOS)
1
2
AD9265
Temperature
Min
Full
Full
Full
Full
Full
Full
1.22
0
−10
40
Full
Full
Full
Full
Full
Full
1.22
0
−92
−10
Full
Full
Full
Full
Full
Full
Full
Full
1.22
0
−10
38
Full
Full
Full
Full
Full
Full
1.22
0
−90
−10
Full
Full
1.79
1.75
Typ
Max
Unit
SVDD
0.6
+10
132
V
V
μA
μA
kΩ
pF
SVDD
0.6
−135
+10
V
V
μA
μA
kΩ
pF
SVDD
0.6
+10
128
V
V
μA
μA
kΩ
pF
V
V
26
2
26
2
26
5
1.70
0.2
2.1
0.6
−134
+10
26
5
V
V
μA
μA
kΩ
pF
V
V
Full
Full
0.2
0.05
V
V
Full
Full
290
1.15
345
1.25
400
1.35
mV
V
Full
Full
160
1.15
200
1.25
230
1.35
mV
V
Pull-up.
Pull-down.
Rev. D | Page 7 of 44
AD9265
Data Sheet
SWITCHING SPECIFICATIONS
−1.0 dBFS differential input, 1.0 V internal reference, and DCS enabled, unless otherwise noted.
Table 4.
Parameter
CLOCK INPUT PARAMETERS
Input Clock Rate
Conversion Rate2
DCS Enabled
DCS Disabled
CLK Period—Divide-by-1 Mode (tCLK)
CLK Pulse Width High (tCH)
Divide-by-1 Mode, DCS Enabled
Divide-by-1 Mode, DCS Disabled
Divide-by-3 Mode, Divide-by-5 Mode, and
Divide-by-7 Mode, DCS Enabled3
Divide-by-2 Mode, Divide-by-4 Mode, Divideby-6 Mode and Divide-by-8 Mode, DCS
Enabled or DCS Disabled3
Aperture Delay (tA)
Aperture Uncertainty (Jitter, tJ)
DATA OUTPUT PARAMETERS
CMOS Mode
Data Propagation Delay (tPD)
DCO Propagation Delay (tDCO)4
DCO to Data Skew (tSKEW)
Pipeline Delay (Latency)
LVDS Mode
Data Propagation Delay (tPD)
DCO Propagation Delay (tDCO)4
DCO to Data Skew (tSKEW)
Pipeline Delay (Latency)
Wake-Up Time5
OUT-OF-RANGE RECOVERY TIME
Temp
AD9265BCPZ-801
Min
Typ Max
Full
AD9265BCPZ-1051
Min
Typ Max
625
Full
Full
Full
20
10
12.5
Full
Full
3.75
5.9
0.8
Full
0.8
Full
Full
6.25
6.25
AD9265BCPZ-1251
Min Typ Max
625
80
80
20
10
9.5
8.75
6.6
2.85
4.5
0.8
4.75
4.75
105
105
20
10
8
6.65
5.0
2.4
3.8
0.8
0.8
1.0
0.07
4
4
625
MHz
125
125
MSPS
MSPS
ns
5.6
4.2
ns
ns
ns
0.8
1.0
0.07
Unit
ns
1.0
0.07
ns
ps rms
Full
Full
Full
Full
2.4
2.7
0.3
2.8
3.4
0.6
12
3.4
4.2
0.9
2.4
2.7
0.3
2.8
3.4
0.6
12
3.4
4.2
0.9
2.4
2.7
0.3
2.8
3.4
0.6
12
3.4
4.2
0.9
ns
ns
ns
Cycles
Full
Full
Full
Full
Full
Full
2.6
3.3
−0.3
3.4
3.8
0.4
12.5
500
2
4.2
4.3
1.2
2.6
3.3
−0.3
3.4
3.8
0.4
12.5
500
2
4.2
4.3
1.2
2.6
3.3
−0.3
3.4
3.8
0.4
12.5
500
2
4.2
4.3
1.2
ns
ns
ns
Cycles
μs
Cycles
1
The suffix following the part number refers to the model found in the Ordering Guide section.
Conversion rate is the clock rate after the divider.
See the Input Clock Divider section for additional information on using the DCS with the input clock divider.
4
Additional DCO delay can be added by writing to Bit 0 through Bit 4 in SPI Register 0x17 (see Table 17).
5
Wake-up time is defined as the time required to return to normal operation from power-down mode.
2
3
Rev. D | Page 8 of 44
Data Sheet
AD9265
TIMING SPECIFICATIONS
Table 5.
Parameter
SYNC TIMING REQUIREMENTS
tSSYNC
tHSYNC
SPI TIMING REQUIREMENTS
tDS
tDH
tCLK
tS
tH
tHIGH
tLOW
tEN_SDIO
tDIS_SDIO
Conditions
Min
Typ
SYNC to rising edge of CLK setup time
SYNC to rising edge of CLK hold time
Max
0.30
0.40
Setup time between the data and the rising edge of SCLK
Hold time between the data and the rising edge of SCLK
Period of the SCLK
Setup time between CSB and SCLK
Hold time between CSB and SCLK
SCLK pulse width high
SCLK pulse width low
Time required for the SDIO pin to switch from an input to an
output relative to the SCLK falling edge
Time required for the SDIO pin to switch from an output to an
input relative to the SCLK rising edge
ns
ns
2
2
40
2
2
10
10
10
ns
ns
ns
ns
ns
ns
ns
ns
10
ns
Timing Diagrams
N–1
N+4
tA
N+5
N
N+3
VIN
N+1
tCH
tCL
N+2
tCLK
CLK+
CLK–
tDCO
DCO/DCO+
DCO–
LVDS (DDR) MODE
tPD
D0/1+ TO D14/D15+
tSKEW
DEx
– 12
D0/1– TO D14/D15–
DOx
– 12
DEx
– 11
DOx
– 11
DEx
– 10
DOx
– 10
DEx
–9
DOx
–9
DEx
–8
DOx
–8
CMOS MODE
D0 TO D15
Dx – 12
Dx – 11
Dx – 10
Dx – 9
Dx – 8
08502-002
NOTES
1. DEx DENOTES EVEN BIT.
2. DOx DENOTES ODD BIT.
Figure 2. LVDS (DDR) and CMOS Output Mode Data Output Timing
CLK+
tHSYNC
08502-104
tSSYNC
SYNC
Figure 3. SYNC Input Timing Requirements
Rev. D | Page 9 of 44
Unit
AD9265
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 6.
Parameter
Electrical
AVDD to AGND
DRVDD to AGND
SVDD to AGND
VIN+, VIN− to AGND
CLK+, CLK− to AGND
SYNC to AGND
VREF to AGND
SENSE to AGND
VCM to AGND
RBIAS to AGND
CSB to AGND
SCLK/DFS to AGND
SDIO/DCS to AGND
OEB to AGND
PDWN to AGND
LVDS to AGND
LVDS_RS to AGND
DITHER to AGND
D0 through D15 to AGND
DCO to AGND
Environmental
Operating Temperature Range
(Ambient)
Maximum Junction Temperature
Under Bias
Storage Temperature Range
(Ambient)
Rating
−0.3 V to +2.0 V
−0.3 V to +2.0V
−0.3 V to +3.6 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 AVDD + 0.2 V
−0.3 V to SVDD +0.3 V
−0.3 V to SVDD +0.3 V
−0.3V to SVDD + 0.3 V
−0.3 V to DRVDD + 0.2 V
−0.3 V to DRVDD + 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 + 0.2 V
−0.3 V to DRVDD + 0.2 V
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 must be soldered to the ground plane for
the LFCSP package. Soldering the exposed paddle to the customer
board increases the reliability of the solder joints and maximizes
the thermal capability of the package.
Typical θJA is specified for a 4-layer PCB with a solid ground
plane. As shown, 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.
Table 7. Thermal Resistance
Package Type
48-Lead LFCSP
(CP-48-9)
−40°C to +85°C
1
150°C
−65°C to +150°C
Airflow
Velocity
(m/s)
0
1.0
2.5
θJA1, 2
24.5
21.4
19.2
θJC1, 3
1.3
Per JEDEC 51-7, plus JEDEC 25-5 2S2P test board.
Per JEDEC JESD51-2 (still air) or JEDEC JESD51-6 (moving air).
Per MIL-Std 883, Method 1012.1.
4
Per JEDEC JESD51-8 (still air).
2
3
ESD CAUTION
Rev. D | Page 10 of 44
θJB1, 4
12.7
Unit
°C/W
°C/W
°C/W
Data Sheet
AD9265
48
47
46
45
44
43
42
41
40
39
38
37
PDWN
RBIAS
VCM
AVDD
LVDS
VIN–
VIN+
LVDS_RS
DNC
DNC
VREF
SENSE
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
SYNC 1
CLK+ 2
CLK– 3
AVDD 4
AVDD 5
OEB 6
DNC 7
DCO 8
D0 (LSB) 9
D1 10
D2 11
D3 12
AD9265
TOP VIEW
(Not to Scale)
AVDD
DITHER
AVDD
SVDD
CSB
SCLK/DFS
SDIO/DCS
DRVDD
DNC
OR
D15 (MSB)
D14
NOTES
1. DNC = DO NOT CONNECT.
2. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE
PROVIDES THE ANALOG GROUND FOR THE INPUT. THIS EXPOSED
PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION.
08502-003
DRVDD
D4
D5
D6
D7
D8
D9
DRVDD
D10
D11
D12
D13
13
14
15
16
17
18
19
20
21
22
23
24
PARALLEL
CMOS
36
35
34
33
32
31
30
29
28
27
26
25
Figure 4. LFCSP Parallel CMOS Pin Configuration (Top View)
Table 8. Pin Function Descriptions (Parallel CMOS Mode)
Pin No.
Mnemonic
ADC Power Supplies
13, 20, 29
DRVDD
4, 5, 34, 36, 45
AVDD
33
SVDD
7, 28, 39, 40
DNC
0
AGND
ADC Analog
42
43
38
37
47
46
2
3
Digital Input
1
Digital Outputs
9
10
11
12
14
15
16
17
18
19
21
Type
Description
Supply
Supply
Supply
Digital Output Driver Supply (1.8 V Nominal).
Analog Power Supply (1.8 V Nominal).
SPI Input/Output Voltage.
Do Not Connect.
Analog Ground. The exposed thermal pad on the bottom of the package provides
the analog ground for the input. This exposed pad must be connected to ground for
proper operation.
Ground
VIN+
VIN−
VREF
SENSE
RBIAS
VCM
CLK+
CLK−
Input
Input
Input/output
Input
Input/output
Output
Input
Input
Differential Analog Input Pin (+).
Differential Analog Input Pin (−).
Voltage Reference Input/Output.
Voltage Reference Mode Select. See Table 11 for details.
External Reference Bias Resistor.
Common-Mode Level Bias Output for Analog Inputs.
ADC Clock Input—True.
ADC Clock Input—Complement.
SYNC
Input
Digital Synchronization Pin. Slave mode only.
D0 (LSB)
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
Output
Output
Output
Output
Output
Output
Output
Output
Output
Output
Output
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
Rev. D | Page 11 of 44
AD9265
Data Sheet
Pin No.
Mnemonic
22
D11
23
D12
24
D13
25
D14
26
D15 (MSB)
27
OR
8
DCO
SPI Control
31
SCLK/DFS
30
SDIO/DCS
32
CSB
ADC Configuration
6
OEB
35
DITHER
Type
Output
Output
Output
Output
Output
Output
Output
Description
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
CMOS Output Data.
Overrange Output.
Data Clock Output.
Input
Input/output
Input
SPI Serial Clock/Data Format Select Pin in External Pin Mode.
SPI Serial Data I/O/Duty Cycle Stabilizer Pin in External Pin Mode.
SPI Chip Select (Active Low).
Input
Input
41
LVDS_RS
Input
44
LVDS
Input
48
PDWN
Input
Output Enable Input (Active Low).
In external pin mode, this pin sets dither to on (active high). Pull low for control via
SPI in SPI mode.
In external pin mode, this pin sets LVDS reduced swing output mode (active high).
Pull low for control via SPI in SPI mode.
In external pin mode, this pin sets LVDS output mode (active high). Pull low for
control via SPI in SPI mode.
Power-Down Input in External Pin Mode. In SPI mode, this input can be configured
as power-down or standby.
Rev. D | Page 12 of 44
AD9265
48
47
46
45
44
43
42
41
40
39
38
37
PDWN
RBIAS
VCM
AVDD
LVDS
VIN–
VIN+
LVDS_RS
DNC
DNC
VREF
SENSE
Data Sheet
AD9265
TOP VIEW
(Not to Scale)
INTERLEAVED
LVDS
36
35
34
33
32
31
30
29
28
27
26
25
AVDD
DITHER
AVDD
SVDD
CSB
SCLK/DFS
SDIO/DCS
DRVDD
OR+
OR–
D14/15+
D14/15–
NOTES
1. DNC = DO NOT CONNECT.
2. THE EXPOSED THERMAL PAD ON THE BOTTOM OF THE PACKAGE
PROVIDES THE ANALOG GROUND FOR THE INPUT. THIS EXPOSED
PAD MUST BE CONNECTED TO GROUND FOR PROPER OPERATION.
08502-004
DRVDD
D4/5–
D4/5+
D6/7–
D6/7+
D8/9–
D8/9+
DRVDD
D10/11–
D10/11+
D12/13–
D12/13+
13
14
15
16
17
18
19
20
21
22
23
24
SYNC 1
CLK+ 2
CLK– 3
AVDD 4
AVDD 5
OEB 6
DCO– 7
DCO+ 8
D0/1– 9
D0/1+ 10
D2/3– 11
D2/3+ 12
Figure 5. LFCSP Interleaved Parallel LVDS Pin Configuration (Top View)
Table 9. Pin Function Descriptions (Interleaved Parallel LVDS Mode)
Pin No.
Mnemonic
ADC Power Supplies
13, 20, 29
DRVDD
4, 5, 34, 36, 45 AVDD
33
SVDD
39, 40
DNC
0
AGND
ADC Analog
42
43
38
37
47
46
2
3
Digital Input
1
Digital Outputs
10
9
12
11
15
14
17
16
19
18
22
21
24
Type
Description
Supply
Supply
Supply
Digital Output Driver Supply (1.8 V Nominal).
Analog Power Supply (1.8 V Nominal).
SPI Input/Output Voltage.
Do Not Connect.
Analog Ground. The exposed thermal pad on the bottom of the package provides the
analog ground for the input. This exposed pad must be connected to ground for
proper operation.
Ground
VIN+
VIN−
VREF
SENSE
RBIAS
VCM
CLK+
CLK−
Input
Input
Input/output
Input
Input/output
Output
Input
Input
Differential Analog Input Pin (+).
Differential Analog Input Pin (−).
Voltage Reference Input/Output.
Voltage Reference Mode Select. See Table 11 for details.
External Reference Bias Resistor.
Common-Mode Level Bias Output for Analog Inputs.
ADC Clock Input—True.
ADC Clock Input—Complement.
SYNC
Input
Digital Synchronization Pin. Slave mode only.
D0/1+
D0/1−
D2/3+
D2/3−
D4/5+
D4/5−
D6/7+
D6/7−
D8/9+
D8/9−
D10/11+
D10/11−
D12/13+
Output
Output
Output
Output
Output
Output
Output
Output
Output
Output
Output
Output
Output
LVDS Output Data Bit 0/Bit 1 (LSB)—True.
LVDS Output Data Bit 0/Bit 1 (LSB)—Complement.
LVDS Output Data Bit 2/Bit 3—True.
LVDS Output Data Bit 2/Bit 3—Complement.
LVDS Output Data Bit 4/Bit 5—True.
LVDS Output Data Bit 4/Bit 5—Complement.
LVDS Output Data Bit 6/Bit 7—True.
LVDS Output Data Bit 6/Bit 7—Complement.
LVDS Output Data Bit 8/Bit 9 —True.
LVDS Output Data Bit 8/Bit 9—Complement.
LVDS Output Data Bit 10/Bit 11—True.
LVDS Output Data Bit 10/Bit 11—Complement.
LVDS Output Data Bit 12/Bit 13—True.
Rev. D | Page 13 of 44
AD9265
Data Sheet
Pin No.
Mnemonic
23
D12/13−
26
D14/15+
25
D14/15−
28
OR+
27
OR−
8
DCO+
7
DCO−
SPI Control
31
SCLK/DFS
30
SDIO/DCS
32
CSB
ADC Configuration
6
OEB
35
DITHER
Type
Output
Output
Output
Output
Output
Output
Output
Description
LVDS Output Data Bit 12/Bit 13—Complement.
LVDS Output Data Bit 14/Bit 15 (MSB)—True.
LVDS Output Data Bit 14/Bit 15 (MSB)—Complement.
LVDS Overrange Output—True.
LVDS Overrange Output—Complement.
LVDS Data Clock Output—True.
LVDS Data Clock Output—Complement.
Input
Input/output
Input
SPI Serial Clock/Data Format Select Pin in External Pin Mode.
SPI Serial Data I/O/Duty Cycle Stabilizer Pin in External Pin Mode.
SPI Chip Select (Active Low).
Input
Input
41
LVDS_RS
Input
44
LVDS
Input
48
PDWN
Input
Output Enable Input (Active Low).
In external pin mode, this pin sets dither to on (active high). Pull low for control via SPI
in SPI mode.
In external pin mode, this pin sets LVDS reduced swing output mode (active high). Pull
low for control via SPI in SPI mode.
In external pin mode, this pin sets LVDS output mode (active high). Pull low for control
via SPI in SPI mode.
Power-Down Input in External Pin Mode. In SPI mode, this input can be configured as
power-down or standby.
Rev. D | Page 14 of 44
Data Sheet
AD9265
TYPICAL PERFORMANCE CHARACTERISTICS
AVDD = 1.8 V, DRVDD = 1.8 V, SVDD = 1.8 V, sample rate = 125 MSPS, DCS enabled, 1.0 V internal reference, 2 V p-p differential input,
VIN = −1.0 dBFS, and 32k sample, TA = 25°C, unless otherwise noted.
0
–20
–40
–60
SECOND
HARMONIC
–80
THIRD
HARMONIC
–100
10
20
30
40
0
–100
20
30
40
80MSPS
70.1MHz @ –6dBFS
SNR = 74.0dB (80.0dBFS)
SFDR = 100dBc
–20
–60
SECOND
HARMONIC
10
0
–40
–80
0
Figure 9. AD9265-80 Single-Tone FFT with fIN = 200.3 MHz
AMPLITUDE (dBFS)
THIRD
HARMONIC
–100
–60
–80
SECOND
HARMONIC
–100
THIRD
HARMONIC
–120
10
20
30
40
FREQUENCY (MHz)
–140
08502-107
0
Figure 7. AD9265-80 Single-Tone FFT with fIN = 70.1 MHz
0
10
20
30
40
FREQUENCY (MHz)
08502-110
–120
–40
Figure 10. AD9265-80 Single-Tone FFT with fIN = 70.1 MHz @ −6 dBFS with
Dither Enabled
120
0
80MSPS
140.1MHz @ –1dBFS
SNR = 77.7dB (78.7dBFS)
SFDR = 82.2dBc
SFDR (dBFS)
100
SNR/SFDR (dBc AND dBFS)
–20
–40
THIRD
HARMONIC
–60
SECOND
HARMONIC
–80
–100
SNR (dBFS)
80
60
SFDR (dBc)
40
SNR (dBc)
20
–120
10
20
30
FREQUENCY (MHz)
Figure 8. AD9265-80 Single-Tone FFT with fIN = 140.1 MHz
40
0
–100
08502-108
0
–90
–80
–70
–60
–50
–40
–30
INPUT AMPLITUDE (dBFS)
–20
–10
0
08502-111
AMPLITUDE (dBFS)
SECOND
HARMONIC
FREQUENCY (MHz)
80MSPS
70.1MHz @ –1dBFS
SNR = 78.7dB (79.7dBFS)
SFDR = 93.8dBc
–20
AMPLITUDE (dBFS)
THIRD
HARMONIC
–80
–140
08502-106
0
Figure 6. AD9265-80 Single-Tone FFT with fIN = 2.4 MHz
–140
–60
–120
FREQUENCY (MHz)
–140
–40
08502-109
–120
–140
80MSPS
200.3MHz @ –1dBFS
SNR = 76.5dB (77.5dBFS)
SFDR = 81.2dBc
–20
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
80MSPS
2.4MHz @ –1dBFS
SNR = 79.2dB (80.2dBFS)
SFDR = 88.2dBc
Figure 11. AD9265-80 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 98.12 MHz
Rev. D | Page 15 of 44
AD9265
Data Sheet
120
450,000
SFDRFS (DITHER ON)
350,000
NUMBER OF HITS
100
SFDRFS (DITHER OFF)
90
SNRFS (DITHER OFF)
250,000
200,000
150,000
100,000
SNRFS (DITHER ON)
–80
–70
–60
–50
–40
–30
–20
–10
0
INPUT AMPLITUDE (dBFS)
0
08502-112
–90
50,000
08502-115
80
300,000
N – 11
N – 10
N–9
N–8
N –7
N–6
N–5
N–4
N–3
N–2
N–1
N
N+1
N+2
N+3
N+4
N+5
N+6
N+7
N+8
N +9
N + 10
N + 11
SNR/SFDR (dBFS)
110
70
–100
2.17 LSB RMS
400,000
OUTPUT CODE
Figure 15. AD9265-80 Grounded Input Histogram
Figure 12. AD9265-80 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 30 MHz With and Without Dither Enabled
100
4
95
3
SFDR @ +25°C
2
90
85
INL ERROR (LSB)
SNR @ –40°C
80
SFDR @ –40°C
75
SNR @ +25°C
0
–1
–2
SNR @ +85°C
70
0
50
100
150
200
250
300
INPUT FREQUENCY (MHz)
–4
0
10,000
Figure 13. AD9265-80 Single-Tone SNR/SFDR vs.
Input Frequency (fIN) and Temperature with 2 V p-p Full Scale
30,000
40,000
OUTPUT CODE
50,000
60,000
Figure 16. AD9265-80 INL with fIN = 12.5 MHz
105
1.00
0.75
100
0.50
DNL ERROR (LSB)
95
SFDR
90
85
0.25
0
–0.25
–0.50
SNR
80
–0.75
75
25
30
35
40
45
50
55
60
65
70
75
80
SAMPLE RATE (MSPS)
08502-114
SNR/SFDR (dBFS/dBc)
20,000
08502-116
–3
08502-113
65
1
Figure 14. AD9265-80 Single-Tone SNR/SFDR vs. Sample Rate (fS)
with fIN = 70.1 MHz
–1.00
0
10,000
20,000
30,000
40,000
OUTPUT CODE
50,000
Figure 17. AD9265-80 DNL with fIN = 12.5 MHz
Rev. D | Page 16 of 44
60,000
08502-117
SNR/SFDR (dBFS/dBc)
SFDR @ +85°C
INL WITHOUT DITHER
INL WITH DITHER
Data Sheet
AD9265
0
–20
–40
–60
SECOND
HARMONIC
–80
THIRD
HARMONIC
–100
10
20
30
40
50
0
0
–60
SECOND
HARMONIC
THIRD
HARMONIC
10
20
30
40
50
105MSPS
70.1MHz @ –6dBFS
SNR = 73.7dB (79.7dBFS)
SFDR = 92dBc
–20
–40
–80
0
Figure 21. AD9265-105 Single-Tone FFT with fIN = 200.3 MHz
AMPLITUDE (dBFS)
–100
–60
–80
SECOND
HARMONIC
THIRD
HARMONIC
–100
–120
10
20
30
40
50
FREQUENCY (MHz)
–140
08502-119
0
Figure 19. AD9265-105 Single-Tone FFT with fIN = 70.1 MHz
0
10
20
30
40
08502-122
–120
–40
50
FREQUENCY (MHz)
Figure 22. AD9265-105 Single-Tone FFT with fIN = 70.1 MHz at −6dBFS with
Dither Enabled
120
0
105MSPS
140.1MHz @ –1dBFS
SNR = 77.3dB (78.3dBFS)
SFDR = 86dBc
100
SNR/SFDR (dBc AND dBFS)
–20
SFDR (dBFS)
–40
–60
THIRD
HARMONIC
SECOND
HARMONIC
–80
–100
SNR (dBFS)
80
60
SFDR (dBc)
40
SNR (dBc)
20
–120
10
20
30
40
50
FREQUENCY (MHz)
Figure 20. AD9265-105 Single-Tone FFT with fIN = 140.1 MHz
0
–100
08502-120
0
–90
–80
–70
–60
–50
–40
–30
INPUT AMPLITUDE (dBFS)
–20
–10
0
08502-123
AMPLITUDE (dBFS)
–100
FREQUENCY (MHz)
105MSPS
70.1MHz @ –1dBFS
SNR = 78.3dB (79.3dBFS)
SFDR = 89dBc
–20
AMPLITUDE (dBFS)
THIRD
HARMONIC
SECOND
HARMONIC
–80
–140
08502-118
0
Figure 18. AD9265-105 Single-Tone FFT with fIN = 2.4 MHz
–140
–60
–120
FREQUENCY (MHz)
–140
–40
08502-121
–120
–140
105MSPS
200.3MHz @ –1dBFS
SNR = 75.9dB (76.9dBFS)
SFDR = 82dBc
–20
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
105MSPS
2.4MHz @ –1dBFS
SNR = 78.8dB (79.8dBFS)
SFDR = 91dBc
Figure 23. AD9265-105 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 98.12 MHz
Rev. D | Page 17 of 44
AD9265
Data Sheet
120
400,000
SFDRFS (DITHER ON)
2.28 LSB RMS
350,000
110
NUMBER OF HITS
100
SFDRFS (DITHER OFF)
90
SNRFS (DITHER OFF)
150,000
100,000
SNRFS (DITHER ON)
–90
–80
–70
–60
–50
–40
50,000
–30
–20
–10
0
INPUT AMPLITUDE (dBFS)
0
08502-124
70
–100
200,000
08502-127
80
250,000
N – 11
N – 10
N–9
N–8
N –7
N–6
N–5
N–4
N–3
N–2
N–1
N
N+1
N+2
N+3
N+4
N+5
N+6
N+7
N+8
N +9
N + 10
N + 11
SNR/SFDR (dBFS)
300,000
OUTPUT CODE
Figure 27. AD9265-105 Grounded Input Histogram
Figure 24. AD9265-105 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 30 MHz with and without Dither Enabled
100
4
SFDR @ +25°C
SFDR @ –40°C
INL WITHOUT DITHER
INL WITH DITHER
3
95
2
85
INL ERROR (LSB)
SNR @ –40°C
80
75
SNR @ +25°C
0
–1
–2
SNR @ +85°C
70
0
50
100
150
200
250
300
INPUT FREQUENCY (MHz)
–4
0
10,000
Figure 25. AD9265-105 Single-Tone SNR/SFDR vs.
Input Frequency (fIN) and Temperature with 2 V p-p Full Scale
30,000
40,000
OUTPUT CODE
50,000
60,000
Figure 28. AD9265-105 INL with fIN = 12.5 MHz
105
1.00
0.75
100
0.50
SFDR
DNL ERROR (LSB)
95
90
85
0.25
0
–0.25
–0.50
80
SNR
–0.75
75
25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105
SAMPLE RATE (MSPS)
08502-126
SNR/SFDR (dBFS/dBc)
20,000
08502-128
–3
08502-125
65
1
Figure 26. AD9265-105 Single-Tone SNR/SFDR vs. Sample Rate (fS)
with fIN = 70.1 MHz
–1.00
0
10,000
20,000
30,000
40,000
OUTPUT CODE
50,000
Figure 29. AD9265-105 DNL with fIN = 12.5 MHz
Rev. D | Page 18 of 44
60,000
08502-129
SNR/SFDR (dBFS/dBc)
SFDR @ +85°C
90
Data Sheet
AD9265
0
–20
–40
–60
SECOND
HARMONIC
–80
THIRD
HARMONIC
–100
10
20
30
40
50
60
0
–100
0
–60
–80
10
20
30
40
50
60
125MSPS
200.3MHz @ –1dBFS
SNR = 74.7dB (75.7dBFS)
SFDR = 80dBc
–20
–40
THIRD
HARMONIC
0
Figure 33. AD9265-125 Single-Tone FFT with fIN = 140.1 MHz
AMPLITUDE (dBFS)
SECOND
HARMONIC
–100
THIRD
HARMONIC
–60
SECOND
HARMONIC
–80
–100
–120
10
20
30
40
50
60
FREQUENCY (MHz)
–140
08502-131
0
0
AMPLITUDE (dBFS)
–60
–80
30
40
50
60
125MSPS
220.1MHz @ –1dBFS
SNR = 74.3dB (75.3dBFS)
SFDR = 80dBc
–20
–40
SECOND
HARMONIC
20
Figure 34. AD9265-125 Single-Tone FFT with fIN = 200.3 MHz
125MSPS
70.1MHz @ –1dBFS
SNR = 78.0dB (79.0dBFS)
SFDR = 94dBc
–20
10
FREQUENCY (MHz)
Figure 31. AD9265-125 Single-Tone FFT with fIN = 30.3 MHz
0
0
08502-134
–120
–40
THIRD
HARMONIC
–100
THIRD
HARMONIC
–60
SECOND
HARMONIC
–80
–100
–120
0
10
20
30
40
50
60
FREQUENCY (MHz)
08502-132
–120
–40
Figure 32. AD9265-125 Single-Tone FFT with fIN = 70.1 MHz
–140
0
10
20
30
40
50
60
FREQUENCY (MHz)
Figure 35. AD9265-125 Single-Tone FFT with fIN = 220.1 MHz
Rev. D | Page 19 of 44
08502-135
AMPLITUDE (dBFS)
THIRD
HARMONIC
FREQUENCY (MHz)
125MSPS
30.3MHz @ –1dBFS
SNR = 78.6dB (79.6dBFS)
SFDR = 95dBc
–20
AMPLITUDE (dBFS)
SECOND
HARMONIC
–80
–140
08502-130
0
Figure 30. AD9265-125 Single-Tone FFT with fIN = 2.4 MHz
–140
–60
–120
FREQUENCY (MHz)
–140
–40
08502-133
–120
–140
125MSPS
140.1MHz @ –1dBFS
SNR = 76.6dB (77.6dBFS)
SFDR = 89dBc
–20
AMPLITUDE (dBFS)
AMPLITUDE (dBFS)
0
125MSPS
2.4MHz @ –1dBFS
SNR = 78.0dB (79.0dBFS)
SFDR = 88dBc
AD9265
0
120
125MSPS
70.1MHz @ –6dBFS
SNR = 73.5dB (79.5dBFS)
SFDR = 98dBc
SFDR (dBFS)
100
SNR/SFDR (dBc AND dBFS)
–20
–40
–60
–80
SECOND
HARMONIC
THIRD
HARMONIC
–100
10
20
30
40
50
60
Figure 36. AD9265-125 Single-Tone FFT with fIN = 70.1 MHz at −6 dBFS with
Dither Enabled
–15
40
SNR (dBc)
–50
–40
–30
–20
–10
0
Figure 39. AD9265-125 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 2.4 MHz
SNR/SFDR (dBc AND dBFS)
5
3
6
+
4
–120
–60
100
–75
–105
–70
SFDR (dBFS)
–60
2
–80
120
–45
–90
–90
INPUT AMPLITUDE (dBFS)
125MSPS
70.1MHz @ –23dBFS
SNR = 57.3dBc (80.3dBFS)
SFDR = 75.1dBc
–30
AMPLITUDE (dBFS)
SFDR (dBc)
0
–100
08502-136
0
FREQUENCY (MHz)
0
60
20
–120
–140
SNR (dBFS)
80
08502-139
AMPLITUDE (dBFS)
Data Sheet
SNR (dBFS)
80
60
SFDR (dBc)
40
SNR (dBc)
20
18
24
30
36
42
48
54
60
FREQUENCY (MHz)
Figure 37. AD9265-125 Single-Tone FFT with fIN = 70.1 MHz at −23 dBFS with
Dither Disabled, 1M Sample
0
–15
0
–100
SNR/SFDR (dBFS)
AMPLITUDE (dBFS)
–90
4
3
18
24
–20
–10
0
SFDRFS (DITHER OFF)
90
SNRFS (DITHER OFF)
6
80
30
36
42
FREQUENCY (MHz)
48
54
60
70
–100
08502-138
12
–30
100
SNRFS (DITHER ON)
–135
6
–40
110
–75
5
–50
SFDRFS (DITHER ON)
–60
2
–60
120
–45
+
–70
Figure 40. AD9265-125 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 98.12 MHz
125MSPS
70.1MHz @ –23dBFS
SNR = 56.8dBc (79.8dBFS)
SFDR = 86.8dBc
–120
–80
INPUT AMPLITUDE (dBFS)
–30
–105
–90
Figure 38. AD9265-125 Single-Tone FFT with fIN = 70.1 MHz at −23 dBFS with
Dither Enabled, 1M Sample
–90
–80
–70
–60
–50
–40
–30
INPUT AMPLITUDE (dBFS)
–20
–10
0
08502-141
12
08502-137
6
08502-140
–135
Figure 41. AD9265-125 Single-Tone SNR/SFDR vs. Input Amplitude (AIN) with
fIN = 30 MHz With and Without Dither Enabled
Rev. D | Page 20 of 44
Data Sheet
AD9265
100
0
SFDR @ –40°C
95
SFDR/IMD3 (dBc AND dBFS)
SFDR @ +25°C
SNR/SFDR (dBFS/dBc)
SFDR (dBc)
–20
90
SFDR @ +85°C
85
SNR @ –40°C
80
75
SNR @ +25°C
SNR @ +85°C
70
–40
IMD3 (dBc)
–60
–80
SFDR (dBFS)
–100
–120
100
150
200
250
300
INPUT FREQUENCY (MHz)
Figure 42. AD9265-125 Single-Tone SNR/SFDR vs.
Input Frequency (fIN) and Temperature with 2 V p-p Full Scale
–78
–66
–54
–42
0
95
–20
AMPLITUDE (dBFS)
85
80
75
SNR
50
100
150
200
250
300
INPUT FREQUENCY (MHz)
Figure 43. AD9265-125 Single-Tone SNR/SFDR vs.
Input Frequency (fIN) with 1 V p-p Full Scale
–80
–100
0
10
20
30
40
50
60
FREQUENCY (MHz)
Figure 46. AD9265-125 Two-Tone FFT with fIN1 = 29.1 MHz and fIN2 = 32.1 MHz
0
SFDR (dBc)
–20
125MSPS
169.1MHz @ –7dBFS
172.1MHz @ –7dBFS
SFDR = 79.4dBc (86.4dBFS)
–20
–40
AMPLITUDE (dBFS)
SFDR/IMD3 (dBc AND dBFS)
–60
–140
0
IMD3 (dBc)
–60
–80
–100
–40
–120
08502-143
SNR/SFDR (dBFS/dBc)
90
0
–6
125MSPS
29.1MHz @ –7dBFS
32.1MHz @ –7dBFS
SFDR = 94.9dBc (101.9dBFS)
SFDR
65
–18
Figure 45. AD9265-125 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN)
with fIN1 = 169.1 MHz, fIN2 = 172.1 MHz, fS = 125 MSPS
100
70
–30
INPUT AMPLITUDE (dBFS)
08502-146
50
08502-142
0
–140
–90
08502-145
IMD3 (dBFS)
65
SFDR (dBFS)
–120
–40
–60
–80
–100
–120
–78
–66
–54
–42
–30
INPUT AMPLITUDE (dBFS)
–18
–6
Figure 44. AD9265-125 Two-Tone SFDR/IMD3 vs. Input Amplitude (AIN)
with fIN1 = 29.1 MHz, fIN2 = 32.1 MHz, fS = 125 MSPS
Rev. D | Page 21 of 44
–140
0
10
20
30
40
50
60
FREQUENCY (MHz)
Figure 47. AD9265-125 Two-Tone FFT with fIN1 = 169.1 MHz and
fIN2 = 172.1 MHz
08502-147
–140
–90
08502-144
IMD3 (dBFS)
AD9265
Data Sheet
105
1.00
0.75
100
DNL ERROR (LSB)
SNR/SFDR (dBFS/dBc)
0.50
95
SFDR
90
85
0.25
0
–0.25
–0.50
SNR
80
35
45
55
65
75
85
95
105
115
125
SAMPLE RATE (MSPS)
–1.00
08502-148
75
25
0
20,000
30,000
40,000
OUTPUT CODE
50,000
60,000
Figure 51. AD9265-125 DNL with fIN = 9.7 MHz
Figure 48. AD9265-125 Single-Tone SNR/SFDR vs. Sample Rate (fS)
with fIN = 70.1 MHz
450,000
10,000
08502-151
–0.75
100
2.13 LSB RMS
SFDR
400,000
90
SNR/SFDR (dBFS AND dBc)
300,000
250,000
200,000
150,000
100,000
Figure 49. AD9265-125 Grounded Input Histogram
4
2
1
0
–1
–2
–4
10,000
20,000
30,000
40,000
OUTPUT CODE
50,000
60,000
08502-150
–3
0
60
40
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
INPUT COMMON-MODE VOLTAGE (V)
Figure 52. AD9265-125 SNR/SFDR vs. Input Common Mode (VCM)
with fIN = 30 MHz
INL WITHOUT DITHER
INL WITH DITHER
3
70
Figure 50. AD9265-125 INL with fIN = 9.7 MHz
Rev. D | Page 22 of 44
08502-152
OUTPUT CODE
08502-149
N – 11
N – 10
N–9
N–8
N –7
N–6
N–5
N–4
N–3
N–2
N–1
N
N+1
N+2
N+3
N+4
N+5
N+6
N+7
N+8
N +9
N + 10
N + 11
0
SNR
80
50
50,000
INL ERROR (LSB)
NUMBER OF HITS
350,000
Data Sheet
AD9265
EQUIVALENT CIRCUITS
AVDD
VIN+ OR
VIN–
VREF
08502-012
08502-005
6kΩ
Figure 57. Equivalent VREF Circuit
Figure 53. Equivalent Analog Input Circuit
AVDD
SVDD
0.9V
26kΩ
10kΩ
CLK–
350Ω
SDIO/DCS
08502-006
CLK+
08502-008
10kΩ
Figure 58. Equivalent SDIO/DCS Circuit
Figure 54. Equivalent Clock Input Circuit
SVDD
DRVDD
350Ω
SCLK/DFS
PAD
08502-007
08502-009
26kΩ
Figure 59. Equivalent SCLK/DFS Input Circuit
Figure 55. Digital Output
SVDD
AVDD
26kΩ
08502-011
CSB
350Ω
08502-010
SENSE
350Ω
Figure 60. Equivalent CSB Input Circuit
Figure 56. Equivalent SENSE Circuit
Rev. D | Page 23 of 44
AD9265
Data Sheet
AVDD
DITHER,
LVDS OR
LVDS_RS
350Ω
PDWN
26kΩ
08502-061
08502-063
26kΩ
Figure 63. Equivalent DITHER, LVDS, and LVDS_RS Input Circuit
Figure 61. Equivalent PDWN Circuit
DRVDD
26kΩ
350Ω
08502-062
OEB
350Ω
Figure 62. Equivalent OEB Input Circuit
Rev. D | Page 24 of 44
Data Sheet
AD9265
THEORY OF OPERATION
Synchronization capability is provided to allow synchronized
timing between multiple devices.
Programming and control of the AD9265 are accomplished
using a 3-wire SPI-compatible serial interface.
ADC ARCHITECTURE
The AD9265 architecture consists of a front-end sample-andhold input network, followed by a pipelined, switchedcapacitor ADC. The quantized outputs from each stage
combine into a final 16-bit result in the digital correction logic. The
pipelined architecture permits the first stage to operate on a
new input sample and the remaining stages to operate on the
preceding samples. Sampling occurs on the rising edge of the clock.
Each stage of the pipeline, excluding the last, consists of a low
resolution flash ADC connected to a switched-capacitor digitalto-analog converter (DAC) and an interstage residue amplifier
(MDAC). The 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 input stage can be ac- or dc-coupled in differential or
single-ended modes. The output staging block aligns the data,
corrects errors, and passes the data to the output buffers. The
output buffers are powered from a separate supply, allowing
adjustment of the output voltage swing. During power-down,
the output buffers go into a high impedance state.
ANALOG INPUT CONSIDERATIONS
A small resistor in series with each input can help reduce the
peak transient current required from the output stage of the
driving source. A shunt capacitor can be placed across the
inputs to provide dynamic charging currents. This passive
network creates a low-pass filter at the ADC input; therefore,
the precise values are dependent on the application.
In intermediate frequency (IF) undersampling applications, any
shunt capacitors should be reduced. In combination with the
driving source impedance, the shunt capacitors limit the input
bandwidth. Refer to 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,” for more
information on this subject.
BIAS
S
S
CFB
CS
VIN+
CPAR1
CPAR2
H
S
S
CS
VIN–
CPAR1
CPAR2
S
S
BIAS
CFB
08502-037
With the AD9265, the user can sample any fS/2 frequency
segment from dc to 200 MHz, using appropriate low-pass or
band-pass filtering at the ADC inputs with little loss in ADC
performance. Operation to 300 MHz analog input is permitted,
but it occurs at the expense of increased ADC noise and distortion.
Figure 64. Switched Capacitor Input
For best dynamic performance, the source impedances driving
VIN+ and VIN− should be matched, and the inputs should be
differentially balanced.
An internal differential reference buffer creates positive and
negative reference voltages that define the input span of the ADC
core. The span of the ADC core is set by this buffer to 2 × VREF.
Input Common Mode
The analog input to the AD9265 is a differential switchedcapacitor network that has been designed to give optimum
performance while processing a differential input signal.
The clock signal alternatively switches between sample mode
and hold mode (see Figure 64). When the input is switched into
sample mode, the signal source must be capable of charging the
sample capacitors and settling within 1/2 of a clock cycle.
The analog inputs of the AD9265 are not internally dc biased.
In ac-coupled applications, the user must provide this bias
externally. Setting the device so that VCM = 0.5 × AVDD is
recommended for optimum performance, but the device
functions over a wider range with reasonable performance (see
Figure 52). An on-board common-mode voltage reference is
included in the design and is available from the VCM pin.
Optimum performance is achieved when the common-mode
voltage of the analog input is set by the VCM pin voltage
(typically 0.5 × AVDD). The VCM pin must be decoupled to
ground by a 0.1 μF capacitor, as described in the Applications
Information section.
Rev. D | Page 25 of 44
AD9265
Data Sheet
Dither
Static Linearity
The AD9265 has an optional dither mode that can be selected
either through the SPI bus or by using the DITHER pin. Dithering
is the act of injecting a known but random amount of white noise,
commonly referred to as dither, into the input of the ADC.
Dithering has the effect of improving the local linearity at
various points along the ADC transfer function. Dithering
can significantly improve the SFDR when quantizing small
signal inputs, typically when the input level is below −6 dBFS.
Dithering also removes sharp local discontinuities in the INL
transfer function of the ADC and reduces the overall peak-topeak INL.
As shown in Figure 65, the dither that is added to the input of
the ADC through the dither DAC is precisely subtracted out
digitally to minimize SNR degradation. When dithering is enabled,
the dither DAC is driven by a pseudorandom number generator
(PN gen). In the AD9265, the dither DAC is precisely calibrated
to result in only a very small degradation in SNR and SINAD.
The typical SNR and SINAD degradation values, with dithering
enabled, are only 1 dB and 0.8 dB, respectively.
Differential Input Configurations
VIN
ADC CORE
In receiver applications, utilizing dither helps to reduce DNL errors
that cause small signal gain errors. Often this issue is overcome
by setting the input noise 5 dB to 10 dB above the converter
noise. By utilizing dither within the converter to correct the
DNL errors, the input noise requirement can be reduced.
Optimum performance is achieved while driving the AD9265 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 is easily set
with the VCM pin of the AD9265 (see Figure 66), and the
driver can be configured in the filter topology shown to provide
band limiting of the input signal.
DOUT
15pF
200Ω
DITHER
DAC
76.8Ω
VIN
33Ω
90Ω
15Ω
VIN–
ADA4938-2
ADC
33Ω
15Ω
120Ω
200Ω
Large Signal FFT
08502-039
Figure 65. Dither Block Diagram
VCM
VIN+
15pF
Figure 66. Differential Input Configuration Using the ADA4938-2
In most cases, dithering does not improve SFDR for large signal
inputs close to full scale, for example, with a −1 dBFS input. For
large signal inputs, the SFDR is typically limited by front-end
sampling distortion, which dithering cannot improve. However,
even for such large signal inputs, dithering may be useful for
certain applications because it makes the noise floor whiter.
As is common in pipeline ADCs, the AD9265 contains small
DNL errors caused by random component mismatches that
produce spurs or tones that make the noise floor somewhat
randomly colored part-to-part. Although these tones are
typically at very low levels and do not limit SFDR when the
ADC is quantizing large signal inputs, dithering converts these
tones to noise and produces a whiter noise floor.
For baseband applications where SNR is a key parameter,
differential transformer coupling is the recommended input
configuration. An example is shown in Figure 67. To bias the
analog input, the VCM voltage can be connected to the center
tap of the secondary winding of the transformer.
C2
R2
VIN+
R1
2V p-p
49.9Ω
C1
R1
0.1µF
ADC
R2
VIN–
VCM
C2
08502-040
DITHER ENABLE
0.1µF
08502-038
PN GEN
AVDD
5pF
Figure 67. Differential Transformer-Coupled Configuration
Small Signal FFT
For small signal inputs, the front-end sampling circuit typically
contributes very little distortion, and, therefore, the SFDR is
likely to be limited by tones caused by DNL errors due to random
com-ponent mismatches. Therefore, for small signal inputs
(typically, those below −6 dBFS), dithering can significantly
improve SFDR by converting these DNL tones to white noise.
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.
Rev. D | Page 26 of 44
Data Sheet
AD9265
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 AD9265. For applications in
which SNR is a key parameter, differential double balun coupling
is the recommended input configuration (see Figure 68). In this
configuration, the input is ac-coupled and the CML is provided
to each input through a 33 Ω resistor. These resistors compensate
for losses in the input baluns to provide a 50 Ω impedance to
the driver.
Table 10. Example RC Network
Frequency
Range
(MHz)
0 to 100
100 to 300
R1 Series
(Ω Each)
15
10
C1 Differential
(pF)
18
10
C2
0.1µF
2V p-p
R1
R2
VIN+
33Ω
S
S
P
0.1µF
33Ω
C1
0.1µF
R1
ADC
R2
VCM
VIN–
08502-041
PA
C2
Figure 68. Differential Double Balun Input Configuration
VCC
0.1µF
ANALOG INPUT
0Ω 2
1
5, 6, 7, 8
0.1µF
11 20Ω
0.1µF
10pF
15Ω
15Ω
VIN+
100Ω
0.1µF 0Ω
0.1µF
10
100Ω
15Ω
15Ω
0.1µF
10pF
20Ω
9
0.1µF
Figure 69. Differential Input Configuration Using the ADL5562
Rev. D | Page 27 of 44
VIN–
VCM
08502-042
ANALOG INPUT
3
AD9265
5pF
ADL5562
4
C2 Shunt
(pF Each)
Open
10
An alternative to using a transformer-coupled input at frequencies in the second Nyquist zone and higher is to use the
ADL5562 differential driver. The ADL5562 provides three
selectable gain options up to 15.5 dB. An example circuit is
shown in Figure 69; additional filtering between the ADL5562
output and the AD9265 input may be required to reduce outof-band noise. See the ADL5562 data sheet for more
information.
In the double balun and transformer configurations, the value of
the input capacitors and resistors is dependent on the input frequency and source impedance and may need to be reduced or
removed. Table 10 displays recommended values to set the RC
network. However, these values are dependent on the input
signal and should be used only as a starting guide.
0.1µF
R2 Series
(Ω Each)
15
10
AD9265
Data Sheet
VOLTAGE REFERENCE
A stable and accurate voltage reference is built into the AD9265.
The input range can be adjusted by varying the reference voltage
applied to the AD9265, 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 sections that follow. The Reference
Decoupling section describes the best practices PCB layout of
the reference.
This puts the reference amplifier in a noninverting mode with
the VREF output defined as follows:
R2
VREF 0.5 1
R1
The input range of the ADC always equals twice the voltage at
the reference pin for either an internal or an external reference.
VIN+
VIN–
Internal Reference Connection
ADC
CORE
A comparator within the AD9265 detects the potential at the
SENSE pin and configures the reference into four possible modes,
which are summarized in Table 11. If SENSE is grounded, the
reference amplifier switch is connected to the internal resistor
divider (see Figure 70), setting VREF to 1.0 V for a 2.0 V p-p fullscale input. In this mode, with SENSE grounded, the full scale can
also be adjusted through the SPI port by adjusting Bit 6 and Bit 7 of
Register 0x18. These bits can be used to change the full scale to
1.25 V p-p, 1.5 V p-p, 1.75 V p-p, or to the default of 2.0 V p-p,
as shown in Table 17.
Connecting the SENSE pin to the VREF pin switches the reference
amplifier output to the SENSE pin, completing the loop and providing a 0.5 V reference output for a 1 V p-p full-scale input.
VIN+
VIN–
VREF
0.1µF
R2
SENSE
SELECT
LOGIC
0.5V
R1
08502-044
1.0µF
ADC
Figure 71. Programmable Reference Configuration
If the internal reference of the AD9265 is used to drive multiple
converters to improve gain matching, the loading of the reference
by the other converters must be considered. Figure 72 shows
how the internal reference voltage is affected by loading.
0
REFERENCE VOLTAGE ERROR (%)
ADC
CORE
VREF
1.0µF
0.1µF
SELECT
LOGIC
SENSE
ADC
08502-043
0.5V
–0.5
VREF = 0.5V
–1.0
VREF = 1V
–1.5
–2.0
–2.5
–3.0
0.2
If a resistor divider is connected external to the chip, as
shown in Figure 71, the switch again sets to the SENSE pin.
0.4
0.6
0.8
1.0
1.2
1.4
LOAD CURRENT (mA)
1.6
1.8
2.0
Figure 72. VREF Accuracy vs. Load
Table 11. Reference Configuration Summary
Selected Mode
External Reference
SENSE Voltage
AVDD
Resulting VREF (V)
N/A
Resulting Differential Span (V p-p)
2 × external reference
Internal Fixed Reference
VREF
0.5
1.0
Programmable Reference
0.2 V to VREF
Internal Fixed Reference
AGND to 0.2 V
R2
0.5 1
(see Figure 71)
R1
1.0
Rev. D | Page 28 of 44
2 × VREF
2.0
08502-045
Figure 70. Internal Reference Configuration
Data Sheet
AD9265
External Reference Operation
The use of an external reference may be necessary to enhance
the gain accuracy of the ADC or improve thermal drift characteristics. Figure 73 shows the typical drift characteristics of the
internal reference in 1.0 V mode.
This limit helps prevent the large voltage swings of the clock
from feeding through to other portions of the AD9265 while
preserving the fast rise and fall times of the signal that are critical
to low jitter performance.
2.0
1.5
VREF = 1.0V
1.0
0.5
0
0.1µF
CLOCK
INPUT
–0.5
Mini-Circuits®
ADT1-1WT, 1:1Z
0.1µF
XFMR
ADC
AD9265
CLK+
100Ω
50Ω
0.1µF
CLK–
–1.0
–1.5
Figure 75. Transformer-Coupled Differential Clock (Up to 200 MHz)
–20
0
20
40
TEMPERATURE (°C)
60
80
ADC
Figure 73. Typical VREF Drift Update Figure
CLOCK INPUT CONSIDERATIONS
For optimum performance, the AD9265 sample clock inputs,
CLK+ and CLK−, should be clocked with a differential signal.
The signal is typically ac-coupled into the CLK+ and CLK−
pins via a transformer or capacitors. These pins are biased
internally (see Figure 74) and require no external bias.
CLOCK
INPUT
CLK+
50Ω
0.1µF
1nF
CLK–
SCHOTTKY
DIODES:
HSMS2822
Figure 76. Balun-Coupled Differential Clock (625 MHz)
If a low jitter clock source is not available, another option is to
ac couple a differential PECL signal to the sample clock input
pins, as shown in Figure 77. The AD9510/AD9511/AD9512/
AD9513/AD9514/AD9515/AD9516/AD9517/AD9518/AD9520/
AD9522 clock drivers offer excellent jitter performance.
0.1µF
CLOCK
INPUT
AVDD
AD9265
0.1µF
0.1µF
CLK+
AD95xx
CLK+
0.1µF
PECL DRIVER
100Ω
0.1µF
ADC
AD9265
CLK–
50kΩ
240Ω
50kΩ
08502-050
CLOCK
INPUT
0.9V
08502-049
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
6 kΩ load (see Figure 57). The internal buffer generates the
positive and negative full-scale references for the ADC core.
Therefore, the external reference must be limited to a
maximum of 1.0 V.
1nF
240Ω
CLK–
Figure 77. Differential PECL Sample Clock (Up To Rated Sample Rate)
4pF
A third option is to ac-couple a differential LVDS signal to the
sample clock input pins, as shown in Figure 78. The AD9510/
AD9511/AD9512/AD9513/AD9514/AD9515/AD9516/AD9517/
AD9518/AD9520/AD9522 clock drivers offer excellent jitter
performance.
08502-047
4pF
Figure 74. Equivalent Clock Input Circuit
Clock Input Options
The AD9265 has a very flexible clock input structure. Clock input
can be a CMOS, LVDS, LVPECL, or sine wave signal. Regardless
of the type of signal being used, clock source jitter is of the most
concern, as described in the Jitter Considerations section.
Figure 75 and Figure 76 show two preferred methods for clocking
the AD9265. A low jitter clock source is converted from a singleended signal to a differential signal using either an RF transformer
or an RF balun.
0.1µF
0.1µF
CLOCK
INPUT
CLK+
AD95xx
0.1µF
CLOCK
INPUT
LVDS DRIVER
100Ω
0.1µF
ADC
AD9265
CLK–
50kΩ
50kΩ
Figure 78. Differential LVDS Sample Clock (Up to Rated Sample Rate)
Rev. D | Page 29 of 44
08502-051
–2.0
–40
08502-048
SCHOTTKY
DIODES:
HSMS2822
0.1µF
08502-046
REFERENCE VOLTAGE ERROR (mV)
The RF balun configuration is recommended for clock frequencies
at 625 MHz and the RF transformer is recommended for clock
frequencies from 10 MHz to 200 MHz. The back-to-back Schottky
diodes across the transformer/balun secondary limit clock excursions into the AD9265 to approximately 0.8 V p-p differential.
AD9265
Data Sheet
CLOCK
INPUT
1kΩ
AD95xx
OPTIONAL
0.1µF
100Ω
CMOS DRIVER
50Ω1
CLK+
ADC
1kΩ
AD9265
150Ω RESISTOR IS OPTIONAL.
08502-052
CLK–
0.1µF
Figure 79. Single-Ended 1.8 V CMOS Input Clock (Up to 200 MHz)
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 AD9265 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 AD9265. Noise and distortion performance are
nearly flat for a wide range of duty cycles with the DCS enabled.
Jitter in the rising edge of the input is still of paramount 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.
During the time period that 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 applications, it may be
appropriate to disable the duty cycle stabilizer. The DCS can also
be disabled in some cases when using the input clock divider
circuit, see the Input Clock Divider section for additional
information. In all other applications, enabling the DCS circuit is
recommended to maximize ac performance.
The AD9265 contains an input clock divider with the ability to
divide the input clock by integer values between 2 and 8. For
clock divide ratios of 2, 4, 6, or 8, the duty cycle stabilizer (DCS)
is not required because the output of the divider inherently
produces a 50% duty cycle. Enabling the DCS with the clock
divider in these divide modes may cause a slight degradation
in SNR; therefore, disabling the DCS is recommended. For
other divide ratios, divide-by-3, divide-by-5, and divide-by-7,
the duty cycle output from the clock divider is related to the
input clock’s duty cycle. In these modes, if the input clock has
a 50% duty cycle, the DCS is again not required. However, if a
50% duty cycle input clock is not available, the DCS must be
enabled for proper part operation.
The AD9265 clock divider can be synchronized using an external
sync signal applied to the SYNC pin input. Bit 1 and Bit 2 of Register 0x100 allow the clock divider to be resynchronized on every
SYNC signal or only on the first SYNC signal after the register
is written. A valid signal at the SYNC pin causes the clock divider
to reset to its initial state. This synchronization feature allows
multiple parts to have their clock dividers aligned to guarantee
simultaneous input sampling. If the SYNC pin is not used, it
should be tied to AGND.
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 ( SNRLF /10) ]
In the equation, the rms aperture jitter represents the clock
input jitter specification. IF undersampling applications are
particularly sensitive to jitter, as illustrated in Figure 80.
80
0.05ps
75
MEASURED
70
The DCS is enabled by setting the SDIO/DCS pin high when
operating in the external pin mode (see Table 12). If the SPI
mode is enabled, the DCS is enabled by default and can be
disabled by writing a 0x00 to Address 0x09.
0.20ps
65
60
0.50ps
55
1.00ps
50
1.50ps
1
10
100
INPUT FREQUENCY (MHz)
Figure 80. SNR vs. Input Frequency and Jitter
Rev. D | Page 30 of 44
1k
08502-053
VCC
0.1µF
Input Clock Divider
SNR (dBc)
In some applications, it may be acceptable to drive the sample
clock inputs with a single-ended 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 79).
AD9265
0.5
0.20
0.4
0.16
IAVDD
TOTAL POWER (W)
Treat the clock input as an analog signal in cases in which
aperture jitter may affect the dynamic range of the AD9265. To
avoid modulating the clock signal with digital noise, separate
power supplies for clock drivers 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), the output clock should
be retimed by the original clock at the last step.
TOTAL
POWER
Refer to Application Note AN-501, Aperture Uncertainty and
ADC System Performance, and Application Note AN-756,
Sampled Systems and the Effects of Clock Phase Noise and
Jitter, for more information about jitter performance as it
relates to ADCs.
0.2
0.08
0.1
0.04
IDRVDD
This maximum current occurs when every output bit switches on
every clock cycle, that is, a full-scale square wave at the Nyquist
frequency of fCLK/2. In practice, the DRVDD current is established
by the average number of output bits switching, which is
determined by the sample rate and the characteristics of the
analog input signal.
Reducing the capacitive load presented to the output drivers
can minimize digital power consumption. The data shown in
Figure 81, Figure 82, and Figure 83 were taken using a 70 MHz
analog input signal with a 5 pF load on each output driver.
0.20
0.1
0.04
IDRVDD
0
25
50
75
100
0
125
CLOCK FREQUENCY (MSPS)
08502-179
TOTAL POWER (W)
0.08
SUPPLY CURRENT (A)
0.16
0.2
75
85
95
0
105
0.15
0.4
0.12
IAVDD
0.09
0.3
TOTAL
POWER
0.06
0.2
SUPPLY CURRENT (A)
0.5
0.03
0.1
IDRVDD
0
25
35
45
55
65
75
0
ENCODE FREQUENCY (MSPS)
Figure 83. AD9265-80 Power and Current vs. Sample Rate
By asserting PDWN (either through the SPI port or by asserting
the PDWN pin high), the AD9265 is placed in power-down mode.
In this state, the ADC typically dissipates 0.05 mW. During powerdown, the output drivers are placed in a high impedance state.
Asserting the PDWN pin low returns the AD9265 to its normal
operating mode.
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 powerdown mode and then must be recharged when returning to
normal operation.
IAVDD
0.12
65
08502-181
where N is the number of output bits (16 data bits plus 1 DCO,
in the case of the AD9265).
TOTAL POWER (W)
IDRVDD = VDRVDD × CLOAD × fCLK × N
TOTAL
POWER
55
Figure 82. AD9265-105 Power and Current vs. Sample Rate
The maximum DRVDD current (IDRVDD) can be
approximately calculated as
0.3
45
CLOCK FREQUENCY (MSPS)
As shown in Figure 81, the power dissipated by the AD9265 is
proportional to its sample rate. In CMOS output mode, the digital
power dissipation is determined primarily by the strength of the
digital drivers and the load on each output bit.
0.4
35
08502-180
0
25
POWER DISSIPATION AND STANDBY MODE
0.5
0.12
0.3
SUPPLY CURRENT (A)
Data Sheet
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. In addition, when using the SPI
mode, the user can change the function of the external PDWN pin
to either place the part in power-down or standby mode. See the
Memory Map Register Description section for more details.
Figure 81. AD9265-125 Power and Current vs. Sample Rate
Rev. D | Page 31 of 44
AD9265
Data Sheet
DIGITAL OUTPUTS
Digital Output Enable Function (OEB)
The AD9265 output drivers can be configured to interface with
1.8 V CMOS logic families. The AD9265 can also be configured
for LVDS outputs using a DRVDD supply voltage of 1.8 V. The
AD9265 defaults to CMOS output mode but can be placed into
LVDS mode either by setting the LVDS pin high or by using the
SPI port to place the part into LVDS mode. Because most users do
not toggle between CMOS and LVDS mode during operation, use
of the LVDS pin is recommended to avoid any power-up loading
issues on the CMOS configured outputs.
The AD9265 has a flexible three-state ability for the digital output
pins. The three-state mode is enabled using the OEB pin or
through the SPI interface. If the OEB pin is low, the output data
drivers and DCOs are enabled. If the OEB 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 OEB is referenced to the output driver supply (DRVDD)
and should not exceed that supply voltage.
In CMOS output mode, 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, which may affect converter performance.
Applications requiring the ADC to drive large capacitive loads
or large fanouts may require external buffers or latches.
In LVDS output mode two output drive levels can be selected,
either ANSI LVDS or reduced swing LVDS mode. Using the
reduced swing LVDS mode lowers the DRVDD current and
reduces power consumption. The reduced swing LVDS mode
can be selected by asserting the LVDS_RS pin or by selecting
this mode via the SPI port.
The output data format is selected for either offset binary or
twos complement by setting the SCLK/DFS pin when operating in
the external pin mode (see Table 12).
As detailed in Application Note AN-877, 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 12. SCLK/DFS Mode Selection (External Pin Mode)
Voltage at
Pin
AGND
SVDD
SCLK/DFS
Offset binary (default)
Twos complement
SDIO/DCS
DCS disabled
DCS enabled (default)
When using the SPI interface, the data and DCO outputs can be
three-stated by using the output enable bar bit in Register 0x14.
TIMING
The AD9265 provides latched data with a pipeline delay of
12 clock cycles (12.5 clock cycles in LVDS mode). 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 AD9265. These
transients can degrade converter dynamic performance.
The lowest typical conversion rate of the AD9265 is 10 MSPS.
At clock rates below 10 MSPS, dynamic performance can degrade.
Data Clock Output (DCO)
The AD9265 provides a single data clock output (DCO) pin in
CMOS output mode and two differential data clock output (DCO)
pins in LVDS mode intended for capturing the data in an external
register. In CMOS output mode, the data outputs are valid on the
rising edge of DCO, unless the DCO clock polarity has been
changed via the SPI. In LVDS output mode, data is output as
double data rate with the odd numbered output bits transitioning
near the rising edge of DCO and the even numbered output bits
transitioning near the falling edge of DCO. See Figure 2 for a
graphical timing description.
Table 13. Output Data Format
Input (V)
VIN+ − VIN−
VIN+ − VIN−
VIN+ − VIN−
VIN+ − VIN−
VIN+ − VIN−
Condition (V)
< −VREF − 0.5 LSB
= −VREF
=0
= +VREF − 1.0 LSB
> +VREF − 0.5 LSB
Offset Binary Output Mode
0000 0000 0000 0000
0000 0000 0000 0000
1000 0000 0000 0000
1111 1111 1111 1111
1111 1111 1111 1111
Rev. D | Page 32 of 44
Twos Complement Mode
1000 0000 0000 0000
1000 0000 0000 0000
0000 0000 0000 0000
0111 1111 1111 1111
0111 1111 1111 1111
OR
1
0
0
0
1
Data Sheet
AD9265
BUILT-IN SELF-TEST (BIST) AND OUTPUT TEST
The AD9265 includes built-in test features designed to enable
verification of the integrity of the part as well as facilitate board
level debugging. A BIST (built-in self-test) feature is included that
verifies the integrity of the digital datapath of the AD9265. Various
output test options are also provided to place predictable values on
the outputs of the AD9265.
The outputs are not disconnected during this test, so the PN
sequence can be observed as it runs. The PN sequence can be
continued from its last value or reset from the beginning, based
on the value programmed in Register 0x0E, Bit 2. The BIST
signature result varies based on the part configuration.
BUILT-IN SELF-TEST (BIST)
The output test options are shown in Table 17. 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 seed value for
the PN sequence tests can be forced if the PN reset bits are used
to hold the generator in reset mode 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
Application Note AN-877, Interfacing to High Speed ADCs via SPI.
The BIST is a thorough test of the digital portion of the selected
AD9265 signal path. When enabled, the test runs from an internal
pseudorandom noise (PN) source through the digital datapath
starting at the ADC block output. The BIST sequence runs for
512 cycles and stops. The BIST signature value is placed in
Register 0x24 and Register 0x25.
OUTPUT TEST MODES
Rev. D | Page 33 of 44
AD9265
Data Sheet
SERIAL PORT INTERFACE (SPI)
The AD9265 serial port interface (SPI) allows the user to configure
the converter for specific functions or operations through a
structured register space provided inside the ADC. The SPI
gives the user added flexibility and customization, depending on
the application. Addresses are accessed via the serial port and can
be written to or read from via the port. Memory is organized into
bytes that can be further divided into fields, which are documented
in the Memory Map section. For detailed operational
information, see Application Note AN-877, Interfacing to High
Speed ADCs via SPI.
CONFIGURATION USING THE SPI
Three pins define the SPI of this ADC: the SCLK/DFS pin, the
SDIO/DCS pin, and the CSB pin (see Table 14). The SCLK/DFS
(a serial clock) is used to synchronize the read and write data
presented from and to the ADC. The SDIO/DCS (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 14. Serial Port Interface Pins
Pin Mnemonic
SCLK/DFS
SDIO/DCS
CSB
Function
Serial clock. The SCLK function of the pin is for
the serial shift clock input, which is used to
synchronize serial interface reads and writes.
SDIO is the serial data input/output function of
the pin. A dual-purpose pin that typically
serves as an input or an output, depending on
the instruction being sent and the relative
position in the timing frame.
Chip select bar. An active low control that
gates the read and write cycles.
The falling edge of the CSB, in conjunction with the rising edge
of the SCLK, determines the start of the framing. See Figure 84
and Table 5 for an example of the serial timing and its
definitions.
Other modes involving the CSB are available. The CSB can be
held low indefinitely, which permanently enables the device;
this is called streaming. The CSB can stall high between bytes to
allow for additional external timing. When CSB is tied high at
power-up, SPI functions are placed in high impedance mode.
This mode turns on any SPI pin secondary functions. When
CSB is toggled low after power-up, the part remains in SPI
mode and does not revert back to pin mode.
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.
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.
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 Application Note AN-877, Interfacing to
High Speed ADCs via SPI.
HARDWARE INTERFACE
The pins described in Table 14 comprise the physical interface
between the user programming device and the serial port of the
AD9265. 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 AD9265 has a separate supply pin for the SPI interface,
SVDD. The SVDD pin can be set at any level between 1.8 V
and 3.3 V to enable operation with a SPI bus at these voltages
without requiring level translation. If the SPI port is not used,
SVDD can be tied to the DRVDD voltage.
The SPI interface is flexible enough to be controlled by either
FPGAs or microcontrollers. One method for SPI configuration
is described in detail in Application Note AN-812, MicrocontrollerBased 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 AD9265 to prevent these signals from transitioning at the converter inputs during critical sampling periods.
Some pins serve a dual function when the SPI interface is not
being used. When the pins are tied to AVDD or ground during
device power-on, they are associated with a specific function.
The Digital Outputs section describes those alternate functions
that are supported on the AD9265.
Rev. D | Page 34 of 44
Data Sheet
AD9265
CONFIGURATION WITHOUT THE SPI
SPI ACCESSIBLE FEATURES
In applications that do not interface to the SPI control registers,
the SDIO/DCS 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 duty cycle stabilizer and output data
format feature control. In this mode, connect the CSB chip
select to AVDD, which disables the serial port interface.
Table 16 provides a brief description of the general features that
are accessible via the SPI. These features are described in detail
in Application Note AN-877, Interfacing to High Speed ADCs via
SPI. The AD9265 part-specific features are described in detail
following Table 17, the external memory map register table.
Table 16. Features Accessible Using the SPI
Feature
Name
Mode
The OEB pin, the DITHER pin, the LVDS pin, the LVDS_RS
pin, and the PDWN pin are active control lines in both external
pin mode and SPI mode. The input from these pins or the SPI
register setting is used to determine the mode of operation for
the part.
Clock
Table 15. Mode Selection
Pin
SDIO/DCS
SCLK/DFS
OEB
PDWN
LVDS
LVDS_RS
DITHER
External
Voltage
SVDD (default)
AGND
SVDD
AGND (default)
DRVDD
AGND (default)
AVDD
AGND (default)
AGND (default)
AVDD
AGND (default)
AVDD
AGND (default)
AVDD
Offset
Configuration
Duty cycle stabilizer enabled
Duty cycle stabilizer disabled
Twos complement enabled
Offset binary enabled
Outputs in high impedance
Outputs enabled
Chip in power-down or standby
mode
Normal operation
CMOS output mode
LVDS output mode
ANSI LVDS output levels
Reduced swing LVDS output
levels
Dither disabled
Dither enabled
tHIGH
tDS
tS
tDH
Test I/O
Output Mode
Output Phase
Output Delay
VREF
Description
Allows the user to set either power-down mode or
standby mode
Allows the user to access the DCS, set the clock
divider, set the clock divider phase, and enable
the SYNC input
Allows the user to digitally adjust the converter
offset
Allows the user to set test modes to have
known data on output bits
Allows the user to set the output mode
Allows the user to set the output clock polarity
Allows the user to vary the DCO delay
Allows the user to set the reference voltage
tCLK
tH
tLOW
CSB
SCLK DON’T CARE
R/W
W1
W0
A12
A11
A10
A9
A8
A7
D5
D4
D3
D2
D1
D0
DON’T CARE
08502-055
SDIO DON’T CARE
DON’T CARE
Figure 84. Serial Port Interface Timing Diagram
Rev. D | Page 35 of 44
AD9265
Data Sheet
MEMORY MAP
READING THE MEMORY MAP REGISTER TABLE
Default Values
Each row in the memory map register table has eight bit locations.
The memory map is roughly divided into four sections: the chip
configuration registers (Address 0x00 to Address 0x02); the
transfer register (Address 0xFF); the ADC functions registers,
including setup, control, and test (Address 0x08 to Address 0x30);
and the digital feature control register (Address 0x100).
After the AD9265 is reset, critical registers are loaded with
default values. The default values for the registers are given in
the memory map register table, Table 17.
The memory map register table (see Table 17) documents the
default hexadecimal value for each hexadecimal address shown.
The column with the heading, Bit 7 (MSB), is the start of the
default hexadecimal value given. For example, Address 0x18,
the VREF select register, has a hexadecimal default value of 0xC0.
This means that Bit 7 = 1, Bit 6 = 1, and the remaining bits are 0s.
This setting is the default reference selection setting. The default
value uses a 2.0 V p-p reference. For more information on this
function and others, see Application Note AN-877, Interfacing to
High Speed ADCs via SPI. This document details the functions
controlled by Register 0x00 to Register 0xFF. The remaining
register, Register 0x100, is documented in the Memory Map
Register Description section.
Logic Levels
An explanation of logic level terminology follows:
“Bit is set” is synonymous with “bit is set to Logic 1” or
“writing Logic 1 for the bit.”
“Clear a bit” is synonymous with “bit is set to Logic 0” or
“writing Logic 0 for the bit.”
Transfer Register Map
Address 0x08 to Address 0x18 are shadowed. Writes to these
addresses do not affect part operation until a transfer command
is issued by writing 0x01 to Address 0xFF, setting the transfer bit.
This allows these registers to be updated internally and simultaneously when the transfer bit is set. The internal update takes
place when the transfer bit is set, and the bit autoclears.
Open Locations
All address and bit locations that are not included in Table 17
are not currently supported for this device. Unused bits of a
valid address location should be written with 0s. Writing to these
locations is required only when part of an address location is open
(for example, Address 0x18). If the entire address location is
open (for example, Address 0x13), this address location should not
be written.
Rev. D | Page 36 of 44
Data Sheet
AD9265
MEMORY MAP REGISTER TABLE
All address and bit locations that are not included in Table 17 are not currently supported for this device.
Table 17. Memory Map Registers
Addr. Register
(Hex)
Name
Bit 7 (MSB)
Chip Configuration Registers
0x00
SPI port
0
configuration
0x01
0x02
Chip ID
Chip grade
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0 (LSB)
Default
Value
(Hex)
LSB first
Soft reset
1
1
Soft reset
LSB
first
0
0x18
Open
Open
Open
Transfer
8-bit Chip ID[7:0], AD9265 = 0x64 (default)
Speed grade ID
Open Open
01 = 125 MSPS
10 = 105 MSPS
11 = 80 MSPS
Open
Open
Open
Open
Open
Open
Open
Open
ADC Functions Registers
0x08
Power
1
modes
Open
External
power-down
pin function
0 = powerdown
1 = standby
Open
Open
Open
0x09
Global clock
Open
Open
Open
Open
Open
0x0B
Clock divide
(global)
Open
Open
Open
Open
Open
0x0D
Test mode
Open
Open
Reset PN23
generator
Reset PN9
generator
Open
0x0E
BIST enable
Open
Open
Open
Open
Open
Transfer Register
0xFF
Transfer
Rev. D | Page 37 of 44
0x64
Internal
power-down
mode
00 = normal
operation
01 = full powerdown
10 = standby
11 = normal
operation
Open
Open
Duty
cycle
stabilizer
(default)
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
Output test mode
000 = off (default)
001 = midscale short
010 = positive FS
011 = negative FS
100 = alternating checkerboard
101 = PN 23 sequence
110 = PN 9 sequence
111 = one/zero word toggle
Reset BIST Open
BIST
sequence
enable
Default Notes/
Comments
The nibbles are
mirrored so
LSB-first mode
or MSB-first
mode registers
correctly,
regardless of
shift mode
Read only
Speed grade ID
used to
differentiate
devices; read
only
0x00
Synchronously
transfers data
from the
master shift
register to the
slave
0x80
Determines
various generic
modes of chip
operation
0x01
0x00
Clock divide
values other
than 000
automatically
cause the duty
stabilizer to
become active.
0x00
When this
register is set,
the test data is
placed on the
output pins in
place of normal
data
0x04
AD9265
Addr.
(Hex)
0x14
Register
Name
Output
mode
0x16
Data Sheet
Bit 7 (MSB)
Drive
strength
0 = ANSI LVDS
1 = reduced
LVDS
Bit 6
Output
type
0 = CMOS
1 = LVDS
Bit 5
Open
Bit 4
Output
enable
bar
Bit 3
Open
Clock phase
control
Invert DCO
clock
Open
Open
Open
Open
0x17
DCO output
delay
Open
Open
Open
0x18
VREF select
Reference voltage selection
00 = 1.25 V p-p
01 = 1.5 V p-p
10 = 1.75 V p-p
11 = 2.0 V p-p (default)
BIST
signature LSB
0x25
BIST
signature
MSB
0x30
Dither
Open
enable
Digital Feature Control Register
0x100 Sync control
Open
Open
0x24
Open
Open
Open
Open
Open
Bit 2
Output
invert
Bit 1
Bit 0 (LSB)
Output
format
00 = offset binary
01 = twos
complement
01 = gray code
11 = offset binary
Input clock divider phase adjust
000 = no delay
001 = 1 input clock cycle
010 = 2 input clock cycles
011 = 3 input clock cycles
100 = 4 input clock cycles
101 = 5 input clock cycles
110 = 6 input clock cycles
111 = 7 input clock cycles
DCO clock delay
(delay = 2500 ps × register value/31)
00000 = 0 ps
00001 = 81 ps
00010 = 161 ps
…
11110 = 2419 ps
11111 = 2500 ps
Open Open
Open
Open
Default
Value
(Hex)
0x00
0x00
Default Notes/
Comments
Configures the
outputs and
the format of
the data
Allows
selection of
clock delays
into the input
clock divider
0x00
0xC0
BIST Signature[7:0]
0x00
Read only
BIST Signature[15:8]
0x00
Read only
Dither
enable
Open
Open
Open
Open
Open
0x00
Open
Clock
divider
next sync
only
Clock
divider
sync
enable
Master
sync
enable
0x00
Rev. D | Page 38 of 44
Data Sheet
AD9265
MEMORY MAP REGISTER DESCRIPTIONS
For additional information about functions controlled in
Register 0x00 to Register 0xFF, see Application Note AN-877,
Interfacing to High Speed ADCs via SPI.
and to ignore the rest. The clock divider sync enable bit (Address
0x100, Bit 1) resets after it syncs.
Bit 1—Clock Divider Sync Enable
Bits[7:3]—Reserved
Bit 1 gates the sync pulse to the clock divider. The sync signal is
enabled when Bit 1 is high and Bit 0 is high. This is continuous
sync mode.
These bits are reserved.
Bit 0—Master Sync Enable
Bit 2—Clock Divider Next Sync Only
Bit 0 must be high to enable any of the sync functions. If the
sync capability is not used, this bit should remain low to
conserve power.
Sync Control (Register 0x100)
If the master sync enable bit (Address 0x100, Bit 0) and the
clock divider sync enable bit (Address 0x100, Bit 1) are high, Bit 2
allows the clock divider to sync to the first sync pulse it receives
Rev. D | Page 39 of 44
AD9265
Data Sheet
APPLICATIONS INFORMATION
DESIGN GUIDELINES
Before starting design and layout of the AD9265 as a system,
it is recommended that the designer become familiar with these
guidelines, which discuss the special circuit connections and
layout requirements that are needed for certain pins.
Power and Ground Recommendations
When connecting power to the AD9265, it is recommended
that two separate 1.8 V supplies be used. Use one supply for
analog (AVDD); use a separate supply for the digital outputs
(DRVDD). 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. The power supply for the
SPI port, SVDD, should not contain excessive noise and should
also be bypassed close to the part.
A single PCB ground plane should be sufficient when using the
AD9265. With proper decoupling and smart partitioning of the
PCB analog, digital, and clock sections, optimum performance
is easily achieved.
LVDS Operation
The AD9265 can be configured for CMOS or LVDS output mode
on power-up using the LVDS pin, Pin 44. If LVDS operation is
desired, connect Pin 44 to AVDD. LVDS operation can also be
enabled through the SPI port. If CMOS operation is desired,
connect Pin 44 to AGND.
Exposed Paddle Thermal Heat Slug Recommendations
It is mandatory that the exposed paddle on the underside of the
ADC be connected to the analog ground (AGND) to achieve
the best electrical and thermal performance. A continuous,
exposed (no solder mask) copper plane on the PCB should
mate to the AD9265 exposed paddle, Pin 0.
To maximize the coverage and adhesion between the ADC and
the PCB, overlay a silkscreen to partition the continuous plane on
the PCB into several uniform sections. This provides several tie
points between the ADC and the PCB during the reflow process.
Using one continuous plane with no partitions guarantees only
one tie point between the ADC and the PCB. For detailed
information about packaging and PCB layout of chip scale
packages, see Application Note AN-772, A Design and
Manufacturing Guide for the Lead Frame Chip Scale Package
(LFCSP).
VCM
Decouple the VCM pin to ground with a 0.1 μF capacitor, as
shown in Figure 67.
RBIAS
The AD9265 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
Decouple the VREF pin externally 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
AD9265 to keep these signals from transitioning at the converter
inputs during critical sampling periods.
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.
Rev. D | Page 40 of 44
Data Sheet
AD9265
OUTLINE DIMENSIONS
DETAIL A
(JEDEC 95)
7.10
7.00 SQ
6.90
37
36
48
1
0.50
BSC
5.65
5.50 SQ
5.35
EXPOSED
PAD
TOP VIEW
PKG-003641/004499
0.80
0.75
0.70
END VIEW
SEATING
PLANE
0.45
0.40
0.35
24
P IN 1
IN D IC ATO R AR E A OP T I O N S
(SEE DETAIL A)
13
BOTTOM VIEW
0.05 MAX
0.02 NOM
COPLANARITY
0.08
0.20 REF
0.20 MIN
5.50 REF
FOR PROPER CONNECTION OF
THE EXPOSED PAD, REFER TO
THE PIN CONFIGURATION AND
FUNCTION DESCRIPTIONS
SECTION OF THIS DATA SHEET.
COMPLIANT TO JEDEC STANDARDS MO-220-WKKD
10-10-2018-B
PIN 1
INDICATOR
AREA
0.30
0.23
0.18
Figure 85. 48-Lead Lead Frame Chip Scale Package [LFCSP]
7 mm × 7 mm Body and 0.75 mm Package Height
(CP-48-9)
Dimensions shown in millimeters
ORDERING GUIDE
Model1
AD9265BCPZ-125
AD9265BCPZRL7-125
AD9265BCPZ-105
AD9265BCPZRL7-105
AD9265BCPZ-80
AD9265BCPZRL7-80
AD9265-125EBZ
AD9265-FMC-125EBZ
AD9265-105EBZ
AD9265-80EBZ
1
Temperature Range
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
Package Description
48-Lead Lead Frame Chip Scale Package [LFCSP]
48-Lead Lead Frame Chip Scale Package [LFCSP]
48-Lead Lead Frame Chip Scale Package [LFCSP]
48-Lead Lead Frame Chip Scale Package [LFCSP]
48-Lead Lead Frame Chip Scale Package [LFCSP]
48-Lead Lead Frame Chip Scale Package [LFCSP]
Evaluation Board
Evaluation Board
Evaluation Board
Evaluation Board
Z = RoHS Compliant Part.
Rev. D | Page 41 of 44
Package Option
CP-48-9
CP-48-9
CP-48-9
CP-48-9
CP-48-9
CP-48-9
AD9265
Data Sheet
NOTES
Rev. D | Page 42 of 44
Data Sheet
AD9265
NOTES
Rev. D | Page 43 of 44
AD9265
Data Sheet
NOTES
©2009–2020 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D08502-11/20(D)
Rev. D | Page 44 of 44
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