ADC08D1500 Datasheet by Texas Instruments

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I TEXAS INSTRUMENTS
ADC08D1500
www.ti.com
SNAS316G JUNE 2005REVISED APRIL 2013
ADC08D1500 High Performance, Low Power, Dual 8-Bit, 1.5 GSPS A/D Converter
Check for Samples: ADC08D1500
1FEATURES DESCRIPTION
The ADC08D1500 is a dual, low power, high
2 Internal Sample-and-Hold performance CMOS analog-to-digital converter that
Single +1.9V ±0.1V Operation digitizes signals to 8 bits resolution at sample rates
Choice of SDR or DDR Output Clocking up to 1.7 GSPS. Consuming a typical 1.8 Watts at
1.5 GSPS from a single 1.9 Volt supply, this device is
Interleave Mode for 2x Sample Rate ensured to have no missing codes over the full
Multiple ADC Synchronization Capability operating temperature range. The unique folding and
Ensured No Missing Codes interpolating architecture, the fully differential
comparator design, the innovative design of the
Serial Interface for Extended Control internal sample-and-hold amplifier and the self-
Fine Adjustment of Input Full-Scale Range and calibration scheme enable a very flat response of all
Offset dynamic parameters beyond Nyquist, producing a
Duty Cycle Corrected Sample Clock high 7.25 ENOB with a 748 MHz input signal and a
1.5 GHz sample rate while providing a 10-18 C.E.R.
APPLICATIONS Output formatting is binary and the LVDS digital
outputs are compatible with IEEE 1596.3-1996, with
Direct RF Down Conversion the exception of an adjustable common mode voltage
Digital Oscilloscopes between 0.8V and 1.2V.
Satellite Set-Top Boxes Each converter has a 1:2 demultiplexer that feeds
Communications Systems two LVDS buses and reduces the output data rate on
each bus to half the sample rate. The two converters
Test Instrumentation can be interleaved and used as a single 3 GSPS
ADC.
KEY SPECIFICATIONS The converter typically consumes less than 3.5 mW
Resolution 8 Bits in the Power Down Mode and is available in a 128-
Max Conversion Rate 1.5 GSPS (min) lead, thermally enhanced exposed pad HLQFP and
Error Rate 10-18 (typ) operates over the Industrial (-40°C TA+85°C)
temperature range.
ENOB @ 748 MHz Input 7.25 Bits (typ)
DNL ±0.15 LSB (typ)
Power Consumption
Operating 1.8 W (typ)
Power Down Mode 3.5 mW (typ)
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 2005–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
*9 TEXAS INSTRUMENTS
2
VREF
CLK/2
8-BIT
ADC
VINI+
VINI-
DCLK+
Output
Clock
Generator DCLK-
Data Bus Output
16 LVDS Pairs
DIOUT
DIOUTD
1:2 DEMUX
& LATCH
OR
Control
Logic
I CHANNEL
8-BIT
ADC
VINQ+
VINQ- Data Bus Output
16 LVDS Pairs
DQOUT
DQOUTD
Q CHANNEL
3
CalRun
INPUT
MUX
+
-
+
-
S/H
S/H
VBG
CLK+
CLK-
Control
Inputs
Serial
Interface
1:2 DEMUX
& LATCH
ADC08D1500
SNAS316G JUNE 2005REVISED APRIL 2013
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Block Diagram
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GND
VA
OUTV/SCLK
OutEdge/DDR/SDATA
VA
GND
VCMO
GND
VINI-
VINI+
GND
DR GND
12
16
DR GND
FSR/ECE
CLK+
CLK-
GND
VINQ+
VINQ-
GND
PD
GND
ADC08D1500
20
24
28
CAL
VBG
REXT
DR GND
32
31
30
29
27
26
25
23
22
21
19
18
17
15
14
13
11
10
1
4
8
9
7
6
5
3
2
Tdiode_p
Tdiode_n
DQd0+
DQd0-
DQd1+
DQd1-
GND
DR GND
DQd2+
DQd2-
DQd3+
DQd3-
DQd4+
DQd4-
DQd5+
DQd5-
NC
37
41
DR GND
DQd6+
DQd6-
DQd7+
DQd7-
DQ0+
DQ0-
DQ1+
DQ1-
NC
33
34
35
36
38
39
40
42
43
44
46
47
48
50
51
52
54
55
56
58
59
60
62
63
64
45
49
53
57
61
DQ7+
DQ7-
OR+
OR-
DCLK-
DCLK+
DI7-
DI7+
DI6-
DI6+
DR GND
DI5-
DI5+
DI4-
DI4+
DI3-
DI3+
DI2-
DI2+
71
81
86
91
96
DQ4+
DQ4-
DQ5+
DQ5-
DR GND
DQ6+
DQ6-
DQ2+
DQ2-
DQ3+
DQ3-
76
66
65
67
68
69
70
73
72
74
75
78
77
79
80
83
82
84
85
88
87
89
90
93
92
94
95
128
123
118
108
113
124
127
126
125
119
122
121
120
114
117
116
115
109
112
111
110
104
107
106
105
99
102
101
100
103
98
97
VA
VA
VA
PDQ
VA
VA
VA
VA
DCLK_RST
VA
VDR
VDR
VDR
VDR
VDR
CalDly/DES/SCS
CalRun
DId0+
DId0-
DId1+
DId1-
VDR
NC
DId2+
DId2-
DId3+
DId3-
DId4+
DId4-
DId5+
DId5-
NC
DId6+
DId6-
DId7+
DId7-
DI0+
DI0-
DI1+
DI1-
VDR
NC
VDR
VA
DR GND
*
ADC08D1500
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SNAS316G JUNE 2005REVISED APRIL 2013
Pin Configuration
* Exposed pad on back of package must be soldered to ground plane to ensure rated performance.
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GND
VA
50k
50k
200k
8 pF
GND
VA
50 k:
GND
VA
GND
VA
50k
50k
200k
8 pF
VA
SDATA
DDR
GND
VA
50k
ADC08D1500
SNAS316G JUNE 2005REVISED APRIL 2013
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Pin Descriptions and Equivalent Circuits
Pin Functions
Pin No. Symbol Equivalent Circuit Description
Output Voltage Amplitude and Serial Interface Clock. Tie this pin
high for normal differential DCLK and data amplitude. Ground this
pin for a reduced differential output amplitude and reduced power
consumption. See The LVDS Outputs. When the extended control
3 OutV / SCLK mode is enabled, this pin functions as the SCLK input which clocks
in the serial data. See NORMAL/EXTENDED CONTROL for details
on the extended control mode. See THE SERIAL INTERFACE for
description of the serial interface.
DCLK Edge Select, Double Data Rate Enable and Serial Data
Input. This input sets the output edge of DCLK+ at which the output
data transitions. (See OutEdge Setting). When this pin is floating or
OutEdge / DDR / connected to 1/2 the supply voltage, DDR clocking is enabled.
4SDATA When the extended control mode is enabled, this pin functions as
the SDATA input. See NORMAL/EXTENDED CONTROL for details
on the extended control mode. See THE SERIAL INTERFACE for
description of the serial interface.
DCLK Reset. A positive pulse on this pin is used to reset and
15 DCLK_RST synchronize the DCLK outs of multiple converters. See MULTIPLE
ADC SYNCHRONIZATION for detailed description.
Power Down Pins. A logic high on the PD pin puts the entire device
26 PD into the Power Down Mode.
Calibration Cycle Initiate. A minimum 80 input clock cycles logic low
followed by a minimum of 80 input clock cycles high on this pin
30 CAL initiates the self calibration sequence. See Self Calibration for an
overview of self-calibration and On-Command Calibration for a
description of on-command calibration.
A logic high on the PDQ pin puts only the "Q" ADC into the Power
29 PDQ Down mode.
Full Scale Range Select and Extended Control Enable. In non-
extended control mode, a logic low on this pin sets the full-scale
differential input range to 650 mVP-P. A logic high on this pin sets
the full-scale differential input range to 870 mVP-P. See The Analog
14 FSR/ECE Inputs. To enable the extended control mode, whereby the serial
interface and control registers are employed, allow this pin to float
or connect it to a voltage equal to VA/2. See NORMAL/EXTENDED
CONTROL for information on the extended control mode.
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VA
GND
GND
VA
200k
8 pF
VCMO
Enable AC
Coupling
50k
VA
AGND
VA
AGND
50k
Control from VCMO
VCMO
100
GND
VA
50k
50k
ADC08D1500
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SNAS316G JUNE 2005REVISED APRIL 2013
Pin Functions
Pin No. Symbol Equivalent Circuit Description
Calibration Delay, Dual Edge Sampling and Serial Interface Chip
Select. With a logic high or low on pin 14, this pin functions as
Calibration Delay and sets the number of input clock cycles after
power up before calibration begins (See Self-Calibration). With pin
14 floating, this pin acts as the enable pin for the serial interface
CalDly / DES /
127 input and the CalDly value becomes "0" (short delay with no
SCS provision for a long power-up calibration delay). When this pin is
floating or connected to a voltage equal to VA/2, DES (Dual Edge
Sampling) mode is selected where the "I" input is sampled at twice
the input clock rate and the "Q" input is ignored. See Dual-Edge
Sampling.
LVDS Clock input pins for the ADC. The differential clock signal
must be a.c. coupled to these pins. The input signal is sampled on
18 CLK+ the falling edge of CLK+. See Acquiring the Input for a description
19 CLK- of acquiring the input and THE CLOCK INPUTS for an overview of
the clock inputs.
Analog signal inputs to the ADC. The differential full-scale input
11 VINI+ range of this input is programmable using the FSR pin 14 in normal
10 VINImode and the Input Full-Scale Voltage Adjust register in the
extended control mode. Refer to the VIN specification in the
22 VINQ+ Converter Electrical Characteristics for the full-scale input range in
23 VINQthe normal mode. Refer to REGISTER DESCRIPTION for the full-
scale input range in the extended control mode.
Common Mode Voltage. This pin is the common mode voltage
output in d.c. coupling mode and also serves as the a.c. coupling
mode select input. When d.c. coupling is used, the voltage output
7 VCMO at this pin is required to be the common mode input voltage at VIN+
and VIN. To select a.c. coupling at the analog input, this pin
should be grounded. This pin is capable of sourcing or sinking
100μA. See THE ANALOG INPUT.
31 VBG Bandgap output voltage capable of 100 μA source/sink.
Calibration Running indication. This pin is at a logic high when
126 CalRun calibration is running.
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VDR
DR GND
+
-
+
-
Tdiode_P
Tdiode_N
V
VA
GND
ADC08D1500
SNAS316G JUNE 2005REVISED APRIL 2013
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Pin Functions
Pin No. Symbol Equivalent Circuit Description
External bias resistor connection. Nominal value is 3.3k-Ohms
32 REXT 0.1%) to ground. See Self-Calibration.
Temperature Diode Positive (Anode) and Negative (Cathode).
These pins may be used for die temperature measurements,
34 Tdiode_P however no specified accuracy is implied or ensured. Noise
35 Tdiode_N coupling from adjacent output data signals has been shown to
affect temperature measurements using this feature. See Thermal
Management.
83 / 78 DI7/ DQ7
84 / 77 DI7+ / DQ7+
85 / 76 DI6/ DQ6
86 / 75 DI6+ / DQ6+
89 / 72 DI5/ DQ5
90 / 71 DI5+ / DQ5+
91 / 70 DI4/ DQ4I and Q channel LVDS Data Outputs that are not delayed in the
92 / 69 DI4+ / DQ4+ output demultiplexer. Compared with the DId and DQd outputs,
93 / 68 DI3/ DQ3these outputs represent the later time samples. These outputs
94 / 67 DI3+ / DQ3+ should always be terminated with a 100differential resistor.
95 / 66 DI2/ DQ2
96 / 65 DI2+ / DQ2+
100 / 61 DI1/ DQ1
101 / 60 DI1+ / DQ1+
102 / 59 DI0/ DQ0
103 / 58 DI0+ / DQ0+
104 / 57 DId7/ DQd7
105 / 56 DId7+ / DQd7+
106 / 55 DId6/ DQd6
107 / 54 DId6+ / DQd6+
111 / 50 DId5/ DQd5
112 / 49 DId5+ / DQd5+ I and Q channel LVDS Data Outputs that are delayed by one CLK
113 / 48 DId4/ DQd4cycle in the output demultiplexer. Compared with the DI/DQ
114 / 47 DId4+ / DQd4+ outputs, these outputs represent the earlier time sample. These
115 / 46 DId3/ DQd3outputs should always be terminated with a 100differential
116 / 45 DId3+ / DQd3+ resistor.
117 / 44 DId2/ DQd2
118 / 43 DId2+ / DQd2+
122 / 39 DId1/ DQd1
123 / 38 DId1+ / DQd1+
124 / 37 DId0/ DQd0
125 / 36 DId0+ / DQd0+
Out Of Range output. A differential high at these pins indicates that
the differential input is out of range (outside the range ±VIN/2 as
79 OR+ programmed by the FSR pin in non-extended control mode or the
80 OR- Input Full-Scale Voltage Adjust register setting in the extended
control mode).
Differential Clock outputs used to latch the output data. Delayed
and non-delayed data outputs are supplied synchronous to this
82 DCLK+ signal. This signal is at 1/2 the input clock rate in SDR mode and at
81 DCLK- 1/4 the input clock rate in the DDR mode. The DCLK outputs are
not active during a calibration cycle, therefore this is not
recommended as a system clock.
2, 5, 8, 13,
16, 17, 20, VAAnalog power supply pins. Bypass these pins to ground.
25, 28, 33,
128
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Pin Functions
Pin No. Symbol Equivalent Circuit Description
40, 51 ,62,
73, 88, 99, VDR Output Driver power supply pins. Bypass these pins to DR GND.
110, 121
1, 6, 9, 12,
21, 24, 27, GND Ground return for VA.
41
42, 53, 64,
74, 87, 97, DR GND Ground return for VDR.
108, 119
52, 63, 98, NC No Connection. Make no connection to these pins.
109, 120
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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Absolute Maximum Ratings(1)(2)(3)
Analog Supply Voltage (VA) 2.2V
Supply Difference
VDR - VA0V to 100 mV
Voltage on Any Input Pin
(Except VIN+, VIN- ) 0.15V to (VA+0.15V)
Voltage on VIN+, VIN-
(Maintaining Common Mode) -0.15V to 2.5V
Ground Difference
|GND - DR GND| 0V to 100 mV
Input Current at Any Pin(4) ±25 mA
Package Input Current(4) ±50 mA
Power Dissipation at TA85°C 2.3 W
Human Body Model 2500V
ESD Susceptibility(5)
Machine Model 250V
Soldering Temperature, Infrared,
10 seconds, (Applies to standard plated package only) 235°C
Storage Temperature 65°C to +150°C
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. There is no specification of operation at the
Absolute Maximum Ratings. Operating Ratings indicate conditions for which the device is functional, but do not ensure specific
performance limits. For ensured specifications and test conditions, see the Electrical Characteristics. The ensured specifications apply
only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
(2) All voltages are measured with respect to GND = DR GND = 0V, unless otherwise specified.
(3) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.
(4) When the input voltage at any pin exceeds the power supply limits (that is, less than GND or greater than VA), the current at that pin
should be limited to 25 mA. The 50 mA maximum package input current rating limits the number of pins that can safely exceed the
power supplies with an input current of 25 mA to two. This limit is not placed upon the power, ground and digital output pins.
(5) Human body model is 100 pF capacitor discharged through a 1.5 kresistor. Machine model is 220 pF discharged through ZERO
Ohms.
Operating Ratings(1)(2)
Ambient Temperature Range 40°C TA+85°C
Supply Voltage (VA) +1.8V to +2.0V
Driver Supply Voltage (VDR) +1.8V to VA
Analog Input Common Mode Voltage VCMO ±50mV
0V to 2.15V
(100% duty cycle)
VIN+, VIN- Voltage Range (Maintaining Common Mode) 0V to 2.5V
(10% duty cycle)
Ground Difference
(|GND - DR GND|) 0V
CLK Pins Voltage Range 0V to VA
Differential CLK Amplitude 0.4VP-P to 2.0VP-P
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. There is no specification of operation at the
Absolute Maximum Ratings. Operating Ratings indicate conditions for which the device is functional, but do not ensure specific
performance limits. For ensured specifications and test conditions, see the Electrical Characteristics. The ensured specifications apply
only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
(2) All voltages are measured with respect to GND = DR GND = 0V, unless otherwise specified.
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I / O
GND
VA
TO INTERNAL
CIRCUITRY
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Package Thermal Resistance(1)
Package θJA θJC (Top of Package) θJ-PAD (Thermal Pad)
128-Lead Exposed Pad HLQFP 26°C / W 10°C / W 2.8°C / W
(1) Soldering process must comply with TI’s Reflow Temperature Profile specifications. Refer to www.ti.com/packaging.
Converter Electrical Characteristics
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
STATIC CONVERTER CHARACTERISTICS
DC Coupled, 1MHz LSB
INL Integral Non-Linearity (Best fit) Sine Wave ±0.3 ±0.9 (max)
Overranged
DC Coupled, 1MHz LSB
DNL Differential Non-Linearity Sine Wave ±0.15 ±0.6 (max)
Overranged
Resolution with No Missing Codes 8Bits
LSB
1.5 (min)
VOFF Offset Error -0.45 1.0 LSB
(max)
VOFF_A Extended Control
Input Offset Adjustment Range ±45 mV
DJ Mode
mV
PFSE Positive Full-Scale Error See (4) 0.6 ±25 (max)
mV
NFSE Negative Full-Scale Error See (4) 1.31 ±25 (max)
FS_AD Extended Control
Full-Scale Adjustment Range ±20 ±15 %FS
J Mode
(1) The analog inputs are protected as shown below. Input voltage magnitudes beyond the Absolute Maximum Ratings may damage this
device.
(2) To ensure accuracy, it is required that VAand VDR be well bypassed. Each supply pin must be decoupled with separate bypass
capacitors. Additionally, achieving rated performance requires that the backside exposed pad be well grounded.
(3) Typical figures are at TA= 25°C, and represent most likely parametric norms. Test limits are specified to TI's AOQL (Average Outgoing
Quality Level).
(4) Calculation of Full-Scale Error for this device assumes that the actual reference voltage is exactly its nominal value. Full-Scale Error for
this device, therefore, is a combination of Full-Scale Error and Reference Voltage Error. See Figure 2. For relationship between Gain
Error and Full-Scale Error, see Specification Definitions for Gain Error.
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Converter Electrical Characteristics (continued)
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
NORMAL MODE (Non DES) DYNAMIC CONVERTER CHARACTERISTICS
Normal Mode (non
FPBW Full Power Bandwidth 1.7 GHz
DES)
Error/
B.E.R. Bit Error Rate 10-18 Sample
d.c. to 500 MHz ±0.5 dBFS
Gain Flatness d.c. to 1 GHz ±1.0 dBFS
fIN = 373 MHz, VIN = Bits
7.4 7.0
FSR 0.5 dB (min)
ENOB Effective Number of Bits fIN = 748 MHz, VIN = Bits
7.25
FSR 0.5 dB (min)
fIN = 373 MHz, VIN = dB
46.3 43.9
FSR 0.5 dB (min)
SINAD Signal-to-Noise Plus Distortion Ratio fIN = 748 MHz, VIN = dB
45.4
FSR 0.5 dB (min)
fIN = 373 MHz, VIN = dB
47 44.5
FSR 0.5 dB (min)
SNR Signal-to-Noise Ratio fIN = 748 MHz, VIN = dB
46.3
FSR 0.5 dB (min)
fIN = 373 MHz, VIN = dB
-54.5 -47
FSR 0.5 dB (max)
THD Total Harmonic Distortion fIN = 748 MHz, VIN = dB
-53
FSR 0.5 dB (max)
fIN = 373 MHz, VIN =60 dB
FSR 0.5 dB
2nd Second Harmonic Distortion
Harm fIN = 748 MHz, VIN =57 dB
FSR 0.5 dB
fIN = 373 MHz, VIN =62 dB
FSR 0.5 dB
3rd Third Harmonic Distortion
Harm fIN = 748 MHz, VIN =65 dB
FSR 0.5 dB
fIN = 373 MHz, VIN = dB
56 48.5
FSR 0.5 dB (min)
SFDR Spurious-Free dynamic Range fIN = 748 MHz, VIN = dB
53
FSR 0.5 dB (min)
fIN1 = 321 MHz, VIN
= FSR 7 dB
IMD Intermodulation Distortion -50 dB
fIN2 = 326 MHz, VIN
= FSR 7 dB
(VIN+) (VIN) > + 255
Full Scale
Out of Range Output Code
(In addition to OR Output high) (VIN+) (VIN) < 0
Full Scale
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Converter Electrical Characteristics (continued)
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
INTERLEAVE MODE (DES Pin 127=Float) - DYNAMIC CONVERTER CHARACTERISTICS
FPBW Dual Edge Sampling
Full Power Bandwidth 900 MHz
(DES) Mode
fIN = 748 MHz, VIN = Bits
ENOB Effective Number of Bits 7.2
FSR 0.5 dB (min)
fIN = 748 MHz, VIN = dB
SINAD Signal to Noise Plus Distortion Ratio 45
FSR 0.5 dB (min)
fIN = 748 MHz, VIN = dB
SNR Signal to Noise Ratio 45.5
FSR 0.5 dB (min)
fIN = 748 MHz, VIN = dB
THD Total Harmonic Distortion -53.5
FSR 0.5 dB (max)
2nd fIN = 748 MHz, VIN =
Second Harmonic Distortion -54 dB
Harm FSR 0.5 dB
3rd fIN = 748 MHz, VIN =
Third Harmonic Distortion -64 dB
Harm FSR 0.5 dB
fIN = 748 MHz, VIN = dB
SFDR Spurious Free Dynamic Range 53.4
FSR 0.5 dB (min)
ANALOG INPUT AND REFERENCE CHARACTERISTICS
mVP-P
570 (min)
FSR pin 14 Low 650 mVP-P
730 (max)
VIN Full Scale Analog Differential Input Range mVP-P
790 (min)
FSR pin 14 High 870 mVP-P
950 (max)
mV
VCMO 50 (min)
VCMI Analog Input Common Mode Voltage VCMO VCMO + 50 mV
(max)
Differential 0.02 pF
Analog Input Capacitance, Normal operation(5) (6) Each input pin to 1.6 pF
ground
CIN Differential 0.08 pF
Analog Input Capacitance, DES Mode (6) (5) Each input pin to 2.2 pF
ground
94 (min)
RIN Differential Input Resistance 100 106 (max)
(5) This parameter is specified by design and is not tested in production.
(6) The analog and clock input capacitances are die capacitances only. Additional package capacitances of 0.65 pF differential and 0.95 pF
each pin to ground are isolated from the die capacitances by lead and bond wire inductances.
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Converter Electrical Characteristics (continued)
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
ANALOG OUTPUT CHARACTERISTICS
0.95 V (min)
VCMO Common Mode Output Voltage ICMO = ±100 µA 1.26 1.45 V (max)
TC TA=40°C to
Common Mode Output Voltage Temperature Coefficient 118 ppm/°C
VCMO +85°C
VA= 1.8V 0.60 V
VCMO_L VCMO input threshold to set DC Coupling mode
VL VA= 2.0V 0.66 V
CLOAD Maximum VCMO load Capacitance 80 pF
VCMO
1.20 V (min)
VBG Bandgap Reference Output Voltage IBG = ±100 µA 1.26 1.33 V (max)
TA=40°C to
TC VBG Bandgap Reference Voltage Temperature Coefficient +85°C, 28 ppm/°C
IBG = ±100 µA
CLOAD Maximum Bandgap Reference load Capacitance 80 pF
VBG
TEMPERATURE DIODE CHARACTERISTICS
192 µA vs. 12 µA, 71.23 mV
TJ= 25°C
ΔVBE Temperature Diode Voltage 192 µA vs. 12 µA, 85.54 mV
TJ= 85°C
CHANNEL-TO-CHANNEL CHARACTERISTICS
Offset Match 1 LSB
Zero offset selected
Positive Full-Scale Match 1 LSB
in Control Register
Zero offset selected
Negative Full-Scale Match 1 LSB
in Control Register
Phase Matching (I, F.S.Q) FIN = 1.0 GHz < 1 Degree
Aggressor = 867
MHz F.S.
X-TALK Crosstalk from I (Aggressor) to Q (Victim) Channel -71 dB
Victim = 100 MHz
F.S.
Aggressor = 867
MHz F.S.
X-TALK Crosstalk from Q (Aggressor) to I (Victim) Channel -71 dB
Victim = 100 MHz
F.S.
CLOCK INPUT CHARACTERISTICS
VP-P
0.4 (min)
Sine Wave Clock 0.6 2.0 VP-P
(max)
VID Differential Clock Input Level VP-P
0.4 (min)
Square Wave Clock 0.6 2.0 VP-P
(max)
IIInput Current VIN = 0 or VIN = VA±1 µA
Differential 0.02 pF
CIN Input Capacitance(7)(8)
Each input to ground 1.5 pF
(7) The analog and clock input capacitances are die capacitances only. Additional package capacitances of 0.65 pF differential and 0.95 pF
each pin to ground are isolated from the die capacitances by lead and bond wire inductances.
(8) This parameter is specified by design and is not tested in production.
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Converter Electrical Characteristics (continued)
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
DIGITAL CONTROL PIN CHARACTERISTICS
VIH Logic High Input Voltage See (9) 0.85 x VAV (min)
VIL Logic Low Input Voltage See (9) 0.15 x VAV (max)
CIN Input Capacitance(10)(11) Each input to ground 1.2 pF
DIGITAL OUTPUT CHARACTERISTICS
mVP-P
Measured 400 (min)
differentially, OutV = 710
VA, VBG = Floating mVP-P
920
(12) (max)
VOD LVDS Differential Output Voltage mVP-P
Measured 280 (min)
differentially, OutV = 510
GND, VBG = Floating mVP-P
720
(12) (max)
ΔVOChange in LVDS Output Swing Between Logic Levels ±1 mV
DIFF
VOS Output Offset Voltage, see Figure 1 VBG = Floating 800 mV
VOS Output Offset Voltage, see Figure 1 VBG = VA(12) 1200 mV
ΔVOS Output Offset Voltage Change Between Logic Levels ±1 mV
Output+ & Output-
IOS Output Short Circuit Current ±4 mA
connected to 0.8V
ZODifferential Output Impedance 100 Ohms
VOH CalRun High level output IOH = -400uA (9) 1.65 1.5 V
VOL CalRun Low High level output IOH = 400uA (9) 0.15 0.3 V
POWER SUPPLY CHARACTERISTICS
870 mA
PD = PDQ = Low 770 600 (max)
PD = Low, PDQ =
IAAnalog Supply Current 524 mA
High 1.8 (max)
PD = PDQ = High mA
207 290 mA
PD = PDQ = Low 116 165 (max)
PD = Low, PDQ =
IDR Output Driver Supply Current 0.012 mA
High (max)
PD = PDQ = High mA
1.8 2.2 W
PD = PDQ = Low 1.2 1.45 (max)
PD = Low, PDQ =
PDPower Consumption 3.5 W
High (max)
PD = PDQ = High mW
Change in Full Scale
PSRR1 D.C. Power Supply Rejection Ratio Error with change in 30 dB
VAfrom 1.8V to 2.0V
248 MHz, 50mVP-P
PSRR2 A.C. Power Supply Rejection Ratio 51 dB
riding on VA
(9) This parameter is specified by design and/or characterization and is not tested in production.
(10) This parameter is specified by design and is not tested in production.
(11) The digital control pin capacitances are die capacitances only. Additional package capacitance of 1.6 pF each pin to ground are isolated
from the die capacitances by lead and bond wire inductances.
(12) Tying VBG to the supply rail will increase the output offset voltage (VOS) by 400mv (typical), as shown in the VOS specification above.
Tying VBG to the supply rail will also affect the differential LVDS output voltage (VOD), causing it to increase by 40mV (typical).
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Converter Electrical Characteristics (continued)
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
AC ELECTRICAL CHARACTERISTICS
Normal Mode (non GHz
fCLK1 Maximum Input Clock Frequency 1.7 1.5
DES) or DES Mode (min)
Normal Mode (non
fCLK2 Minimum Input Clock Frequency 200 MHz
DES)
fCLK2 Minimum Input Clock Frequency DES Mode 500 MHz
200 MHz Input % (min)
clock frequency 20
Input Clock Duty Cycle 50 %
1.5 GHz (Normal 80 (max)
Mode)(13)
500MHz Input % (min)
clock frequency 20
Input Clock Duty Cycle 50 %
1.5 GHz (DES 80 (max)
Mode)(13)
tCL Input Clock Low Time See (14) 333 133 ps (min)
tCH Input Clock High Time See (14) 333 133 ps (min)
% (min)
45
DCLK Duty Cycle See (14) 50 %
55 (max)
tRS Reset Setup Time See (14) 150 ps
tRH Reset Hold Time See (14) 250 ps
tSD Synchronizing Edge to DCLK Output Delay tOD + tOSK
Clock
tRPW Reset Pulse Width See (14) 4Cycles
(min)
10% to 90%, CL=
tLHT Differential Low to High Transition Time 250 ps
2.5 pF
10% to 90%, CL=
tHLT Differential High to Low Transition Time 250 ps
2.5 pF
50% of DCLK
transition to 50% of
Data transition, SDR ps
tOSK DCLK to Data Output Skew ±50
Mode (max)
and DDR Mode, 0°
DCLK (14)
DDR Mode, 90°
tSU Data to DCLK Set-Up Time 400 ns
DCLK (14)
DDR Mode, 90°
tHDCLK to Data Hold Time 560 ns
DCLK (14)
Input CLK+ Fall to
tAD Sampling (Aperture) Delay 1.3 ns
Acquisition of Data
tAJ Aperture Jitter 0.4 ps rms
50% of Input Clock
tOD Input Clock to Data Output Delay (in addition to Pipeline Delay) transition to 50% of 3.1 ns
Data transition
(13) This parameter is specified by design and/or characterization and is not tested in production.
(14) This parameter is specified by design and is not tested in production.
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Converter Electrical Characteristics (continued)
The following specifications apply after calibration for VA= VDR = +1.9VDC, OutV = 1.9V, VIN FSR (a.c. coupled) = differential
870mVP-P, CL= 10 pF, Differential, a.c. coupled Sinewave Input Clock, fCLK = 1.5 GHz at 0.5VP-P with 50% duty cycle, VBG =
Floating, Non-Extended Control Mode, SDR Mode, REXT = 3300±0.1%, Analog Signal Source Impedance = 100Ω
Differential. Boldface limits apply for TA= TMIN to TMAX. All other limits TA= 25°C, unless otherwise noted.(1)(2)
Typical Limits Units
Symbol Parameter Conditions (3) (3) (Limits)
DI Outputs 13
DId Outputs 14
Normal 13
Mode
DQ Input
Outputs DES
Pipeline Delay (Latency)(15)(16) Clock
13.5
Mode Cycles
Normal 14
Mode
DQd
Outputs DES 14.5
Mode
Differential VIN step Input
from ±1.2V to 0V to
Over Range Recovery Time 1 Clock
get accurate Cycle
conversion
tWU PD low to Rated Accuracy Conversion (Wake-Up Time) 500 ns
DCS See (15) 1μs
fSCLK Serial Clock Frequency See (15) 100 MHz
tSSU Data to Serial Clock Setup Time See (15) 2.5 ns (min)
tSH Data to Serial Clock Hold Time See (15) 1 ns (min)
Serial Clock Low Time 4ns (min)
Serial Clock High Time 4ns (min)
Clock
tCAL Calibration Cycle Time 1.4 x 105Cycles
Clock
See and Figure 9
tCAL_L CAL Pin Low Time 80 Cycles
(15) (min)
Clock
See , Figure 9 and
tCAL_H CAL Pin High Time 80 Cycles
(15) (min)
CalDly = Low Clock
See Self-Calibration, 225 Cycles
Figure 9 and (15) (min)
tCalDly Calibration delay determined by pin 127 CalDly = High Clock
SeeSelf-Calibration, 231 Cycles
Figure 9 and (15) (max)
(15) This parameter is specified by design and is not tested in production.
(16) Each of the two converters of the ADC08D1500 has two LVDS output buses, which each clock data out at one half the sample rate. The
data at each bus is clocked out at one half the sample rate. The second bus (D0 through D7) has a pipeline latency that is one Input
Clock cycle less than the latency of the first bus (Dd0 through Dd7).
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VD+
VD-
VOS
GND VOD = | VD+ - VD- |
VOD
VD-
VD+
ADC08D1500
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Specification Definitions
APERTURE (SAMPLING) DELAY is the amount of delay, measured from the sampling edge of the CLK input,
after which the signal present at the input pin is sampled inside the device.
APERTURE JITTER (tAJ)is the sample to sample variation in aperture delay. Aperture jitter shows up as input
noise.
CODE ERROR RATE (C.E.R.) is the probability of error and is defined as the probable number of word errors on
the ADC output per unit of time divided by the number of words seen in that amount of time. A C.E.R. of 10-18
corresponds to a statistical error in one word about every four (4) years.
CLOCK DUTY CYCLE is the ratio of the time that the clock wave form is at a logic high to the clock period.
DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1
LSB. Measured at sample rate = 1500 MSPS with a 1MHz input sinewave.
EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) is another method of specifying Signal-to-Noise
and Distortion Ratio, or SINAD. ENOB is defined as (SINAD 1.76) / 6.02 and says that the converter is
equivalent to a perfect ADC of this (ENOB) number of bits.
FULL POWER BANDWIDTH (FPBW) is a measure of the frequency at which the reconstructed output
fundamental drops 3 dB below its low frequency value for a full scale input.
GAIN ERROR is the deviation from the ideal slope of the transfer function. It can be calculated from Offset and
Full-Scale Errors:
Pos. Gain Error = Offset Error Pos. Full-Scale Error
Neg. Gain Error = (Offset Error Neg. Full-Scale Error)
Gain Error = Neg. Full-Scale Error Pos. Full-Scale Error = Pos. Gain Error + Neg. Gain Error
INTEGRAL NON-LINEARITY (INL) is a measure of worst case deviation of the ADC transfer function from an
ideal straight line drawn through the ADC transfer function. The deviation of any given code from this straight line
is measured from the center of that code value step. The best fit method is used.
INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components as a result of two
sinusoidal frequencies being applied to the ADC input at the same time. It is defined as the ratio of the power in
the second and third order intermodulation products to the power in one of the original frequencies. IMD is
usually expressed in dBFS.
LSB (LEAST SIGNIFICANT BIT) is the bit that has the smallest value or weight of all bits. This value is
VFS / 2n
where VFS is the differential full-scale amplitude VIN as set by the FSR input and "n" is the ADC resolution in bits,
which is 8 for the ADC08D1500.
LVDS DIFFERENTIAL OUTPUT VOLTAGE (VOD)is the absolute value of the difference between the VD+ & VD-
outputs; each measured with respect to Ground.
Figure 1.
LVDS OUTPUT OFFSET VOLTAGE (VOS)is the midpoint between the D+ and D- pins output voltage with
respect to ground; i.e., [(VD+) +( VD-)]/2.
MISSING CODES are those output codes that are skipped and will never appear at the ADC outputs. These
codes cannot be reached with any input value.
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THD = 20 x log + . . . + AAf22
f102
Af1
2
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MSB (MOST SIGNIFICANT BIT) is the bit that has the largest value or weight. Its value is one half of full scale.
NEGATIVE FULL-SCALE ERROR (NFSE) is a measure of how far the first code transition is from the ideal 1/2
LSB above a differential -VIN/2. For the ADC08D1500 the reference voltage is assumed to be ideal, so this error
is a combination of full-scale error and reference voltage error.
OFFSET ERROR (VOFF)is a measure of how far the mid-scale point is from the ideal zero voltage differential
input. Offset Error = Actual Input causing average of 8k samples to result in an average code of 127.5.
OUTPUT DELAY (tOD)is the time delay (in addition to Pipeline Delay) after the falling edge of CLK+ before the
data update is present at the output pins.
OVER-RANGE RECOVERY TIME is the time required after the differential input voltages goes from ±1.2V to 0V
for the converter to recover and make a conversion with its rated accuracy.
PIPELINE DELAY (LATENCY) is the number of input clock cycles between initiation of conversion and when
that data is presented to the output driver stage. New data is available at every clock cycle, but the data lags the
conversion by the Pipeline Delay plus the tOD.
POSITIVE FULL-SCALE ERROR (PFSE) is a measure of how far the last code transition is from the ideal 1-1/2
LSB below a differential +VIN/2. For the ADC08D1500 the reference voltage is assumed to be ideal, so this error
is a combination of full-scale error and reference voltage error.
POWER SUPPLY REJECTION RATIO (PSRR) can be one of two specifications. PSRR1 (DC PSRR) is the ratio
of the change in full-scale error that results from a power supply voltage change from 1.8V to 2.0V. PSRR2 (AC
PSRR) is a measure of how well an a.c. signal riding upon the power supply is rejected from the output and is
measured with a 248 MHz, 50 mVP-P signal riding upon the power supply. It is the ratio of the output amplitude of
that signal at the output to its amplitude on the power supply pin. PSRR is expressed in dB.
SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in dB, of the rms value of the input signal at the output
to the rms value of the sum of all other spectral components below one-half the sampling frequency, not
including harmonics or d.c.
SIGNAL TO NOISE PLUS DISTORTION (S/(N+D) or SINAD) is the ratio, expressed in dB, of the rms value of
the input signal at the output to the rms value of all of the other spectral components below half the input clock
frequency, including harmonics but excluding d.c.
SPURIOUS-FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the rms values of the
input signal at the output and the peak spurious signal, where a spurious signal is any signal present in the
output spectrum that is not present at the input, excluding d.c.
TOTAL HARMONIC DISTORTION (THD) is the ratio expressed in dB, of the rms total of the first nine harmonic
levels at the output to the level of the fundamental at the output. THD is calculated as
where Af1 is the RMS power of the fundamental (output) frequency and Af2 through Af10 are the RMS power of
the first 9 harmonic frequencies in the output spectrum.
– Second Harmonic Distortion (2nd Harm) is the difference, expressed in dB, between the RMS power in the
input frequency seen at the output and the power in its 2nd harmonic level at the output.
– Third Harmonic Distortion (3rd Harm) is the difference expressed in dB between the RMS power in the input
frequency seen at the output and the power in its 3rd harmonic level at the output.
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l TEXAS INSTRUMENTS FULLVSCALE TRANSITION MIDVSCALE TRANSWON 1 OFFSET ' ‘ ERROR
ACTUAL
POSITIVE
FULL-SCALE
TRANSITION
-VIN/2
ACTUAL NEGATIVE
FULL-SCALE TRANSITION
1111 1111 (255)
1111 1110 (254)
1111 1101 (253)
MID-SCALE
TRANSITION
(VIN+) < (VIN-) (VIN+) > (VIN-)
0.0V
Differential Analog Input Voltage (+VIN/2) - (-VIN/2)
Output
Code
OFFSET
ERROR
1000 0000 (128)
0111 1111 (127)
0000 0000 (0)
0000 0001 (1)
0000 0010 (2)
IDEAL
POSITIVE
FULL-SCALE
TRANSITION
POSITIVE
FULL-SCALE
ERROR
NEGATIVE
FULL-SCALE
ERROR
IDEAL NEGATIVE
FULL-SCALE TRANSITION
+VIN/2
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Transfer Characteristic
Figure 2. Input / Output Transfer Characteristic
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l TEXAS INSTRUMENTS , —‘ ,_ W M m \
SCLK
1 12 13 16 17 32
Single Register Access
SCS
SDATA Fixed Header Pattern Register Address
MSB LSB
Register Write Data
tSSU
tSH
tOD
tAD
Sample N
D
Sample N+1
Dd
Sample N-1
VIN
CLK, CLK
DCLK+, DCLK-
(0° Phase)
DId, DI
DQd, DQ Sample N-14 and Sample N-13
Sample N-16 and Sample N-15
Sample N-18 and
Sample N-17
tOSK
DCLK+, DCLK-
(90° Phase)
tSU tH
tOD
tAD
Sample N
D
Sample N+1
Dd
Sample N-1
VIN
CLK, CLK
DCLK+, DCLK-
(OutEdge = 0)
DId, DI
DQd, DQ Sample N-16 and Sample N-15
Sample N-18 and
Sample N-17 Sample N-14 and Sample N-13
DCLK+, DCLK-
(OutEdge = 1)
tOSK
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Timing Diagrams
Figure 3. ADC08D1500 Timing — SDR Clocking
Figure 4. ADC08D1500 Timing — DDR Clocking
Figure 5. Serial Interface Timing
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tRH
Synchronizing Edge
tRPW
tRS tSD
CLK
DCLK_RST
DCLK+
OUTEDGE
tRH
Synchronizing Edge
tRPW
tRS tSD
CLK
DCLK_RST
DCLK+
OUTEDGE
CLK
DCLK_RST
tRH
Synchronizing Edge
tRPW
tRS
DCLK+
tSD
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Figure 6. Clock Reset Timing in DDR Mode
Figure 7. Clock Reset Timing in SDR Mode with OUTEDGE Low
Figure 8. Clock Reset Timing in SDR Mode with OUTEDGE High
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CalRun
POWER
SUPPLY
CAL
tCAL
tCAL
Calibration Delay
determined by
CalDly Pin (127)
tCalDly
tCAL_L
tCAL_H
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Figure 9. Self Calibration and On-Command Calibration Timing
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l TEXAS INSTRUMENTS 1U 1U 08 ‘TNL 05 05 04 E °2 E j on 3 on 2 J02 Z 04 >05 -06 m; VINL 710 710 u 255 -50 .25 o 25 50 75 100 OUTPUT CODE TEMPERATURE PC) 1U 1U 08 05 05 04 mm fl °2 fl I DD I DD 2 z a M a 04 rDNL >05 -06 05 710 710 u 255 -50 .25 o 25 50 75 100 OUTPUT CODE TEMPERATURE (°C) 75 | rm. mm: is 74 ‘ E E I6 g 73 F MH “1 z g m ’— ‘ E 14 72 12 71 I0 70 n 400 500 1200 160m -50 .25 u 25 5a 75 mo CLOCK FREQUENCY (MHzp TEMPERATURE WC)
ADC08D1500
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Typical Performance Characteristics
VA=VDR=1.9V, FCLK=1500MHz, TA=25°C unless otherwise stated.
INL INL
vs. vs.
CODE TEMPERATURE
Figure 10. Figure 11.
DNL DNL
vs. vs.
CODE TEMPERATURE
Figure 12. Figure 13.
POWER CONSUMPTION ENOB
vs. vs.
SAMPLE RATE TEMPERATURE
Figure 14. Figure 15.
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l TEXAS INSTRUMENTS a a 7 a m N : 745 MHz 7;, 7 s o o z z m m 7 4 72 \ 7 o 17 1a 19 20 21 0 400 500 1200 1000 VA 1v; CLOCK FREQUENCY (MHz) so 470 7 7 7 F114 :74; MHz 75 455 m E \ m n \ o - z 70 n: 460 \ m z \ w as 455 so 450 0 400 500 1200 1000 -50 -25 u 25 50 75 100 INFuT FREDUENCWMHZ) TEMPERAYURE ("c1 47 a 47 a 45 5 4s 5 E E - /" 9 1: 450 n: 460 z / z w w 455 455 450 450 17 15 19 20 21 0 300 500 900 1200 1500 vA M CLOCK FREQUENCY 1mm
ADC08D1500
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Typical Performance Characteristics (continued)
VA=VDR=1.9V, FCLK=1500MHz, TA=25°C unless otherwise stated.
ENOB ENOB
vs. vs.
SUPPLY VOLTAGE SAMPLE RATE
Figure 16. Figure 17.
ENOB SNR
vs. vs.
INPUT FREQUENCY TEMPERATURE
Figure 18. Figure 19.
SNR SNR
vs. vs.
SUPPLY VOLTAGE SAMPLE RATE
Figure 20. Figure 21.
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l TEXAS INSTRUMENTS 50 750 45 .52 \ \ \\ E46 35¢ \ 9 9' n: a z I "’44 “'55 42 -53 40 60 a nun son 1200 mun -50 .25 o 25 so 75 100 \NPUT FREQUENCY (MHZ) TEMPERATURE (‘6) 750 .52 \__ 35¢ \ Q, a 1 F756 -53 60 17 15 .9 20 2. a we 300 1200 mun VA (V) CLOCK FREQUENCY (MHz) AD 60 55 45 g 356 . n: 3 5° E $54 /_/"\z >55 52 60 50 a we 300 1200 mun -5o .25 a 25 so 75 100 INPUT FREQUENCY (MHZ) 1EMPERATURE 1°C}
ADC08D1500
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Typical Performance Characteristics (continued)
VA=VDR=1.9V, FCLK=1500MHz, TA=25°C unless otherwise stated.
SNR THD
vs. vs.
INPUT FREQUENCY TEMPERATURE
Figure 22. Figure 23.
THD THD
vs. vs.
SUPPLY VOLTAGE SAMPLE RATE
Figure 24. Figure 25.
THD SFDR
vs. vs.
INPUT FREQUENCY TEMPERATURE
Figure 26. Figure 27.
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Typical Performance Characteristics (continued)
VA=VDR=1.9V, FCLK=1500MHz, TA=25°C unless otherwise stated.
SFDR SFDR
vs. vs.
SUPPLY VOLTAGE SAMPLE RATE
Figure 28. Figure 29.
SFDR
vs.
INPUT FREQUENCY Spectral Response at FIN = 373 MHz
Figure 30. Figure 31.
CROSSTALK
vs.
Spectral Response at FIN = 745 MHz SOURCE FREQUENCY
Figure 32. Figure 33.
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Typical Performance Characteristics (continued)
VA=VDR=1.9V, FCLK=1500MHz, TA=25°C unless otherwise stated.
FULL POWER BANDWIDTH
Figure 34.
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FUNCTIONAL DESCRIPTION
The ADC08D1500 is a versatile A/D Converter with an innovative architecture permitting very high speed
operation. The controls available ease the application of the device to circuit solutions. Optimum performance
requires adherence to the provisions discussed here and in the Applications Information Section.
While it is generally poor practice to allow an active pin to float, pins 4, 14 and 127 of the ADC08D1500 are
designed to be left floating without jeopardy. In all discussions throughout this data sheet, whenever a function is
called by allowing a control pin to float, connecting that pin to a potential of one half the VAsupply voltage will
have the same effect as allowing it to float.
OVERVIEW
The ADC08D1500 uses a calibrated folding and interpolating architecture that achieves 7.4 effective bits. The
use of folding amplifiers greatly reduces the number of comparators and power consumption. Interpolation
reduces the number of front-end amplifiers required, minimizing the load on the input signal and further reducing
power requirements. In addition to other things, on-chip calibration reduces the INL bow often seen with folding
architectures. The result is an extremely fast, high performance, low power converter.
The analog input signal that is within the converter's input voltage range is digitized to eight bits at speeds of 200
MSPS to 1.7 GSPS, typical. Differential input voltages below negative full-scale will cause the output word to
consist of all zeroes. Differential input voltages above positive full-scale will cause the output word to consist of
all ones. Either of these conditions at either the "I" or "Q" input will cause the OR (Out of Range) output to be
activated. This single OR output indicates when the output code from one or both of the channels is below
negative full scale or above positive full scale.
Each of the two converters has a 1:2 demultiplexer that feeds two LVDS output buses. The data on these buses
provide an output word rate on each bus at half the ADC sampling rate and must be interleaved by the user to
provide output words at the full conversion rate.
The output levels may be selected to be normal or reduced. Using reduced levels saves power but could result in
erroneous data capture of some or all of the bits, especially at higher sample rates and in marginally designed
systems.
Self-Calibration
A self-calibration is performed upon power-up and can also be invoked by the user upon command. Calibration
trims the 100analog input differential termination resistor and minimizes full-scale error, offset error, DNL and
INL, resulting in maximizing SNR, THD, SINAD (SNDR) and ENOB. Internal bias currents are also set with the
calibration process. All of this is true whether the calibration is performed upon power up or is performed upon
command. Running the self calibration is an important part of this chip's functionality and is required in order to
obtain adequate performance. In addition to the requirement to be run at power-up, self calibration must be re-
run whenever the sense of the FSR pin is changed. For best performance, we recommend that self calibration be
run 20 seconds or more after application of power and whenever the operating temperature changes significantly
relative to the specific system performance requirements. See On-Command Calibration for more information.
Calibration can not be initiated or run while the device is in the power-down mode. See Power Down for
information on the interaction between Power Down and Calibration.
During the calibration process, the input termination resistor is trimmed to a value that is equal to REXT / 33. This
external resistor is located between pin 32 and ground. REXT must be 3300 ±0.1%. With this value, the input
termination resistor is trimmed to be 100 . Because REXT is also used to set the proper current for the Track
and Hold amplifier, for the preamplifiers and for the comparators, other values of REXT should not be used.
In normal operation, calibration is performed just after application of power and whenever a valid calibration
command is given, which is holding the CAL pin low for at least tCAL_L clock cycles, then hold it high for at least
another tCAL_H clock cycles as defined in the Converter Electrical Characteristics. The time taken by the
calibration procedure is specified as tCALin Converter Electrical Characteristics. Holding the CAL pin high upon
power up will prevent the calibration process from running until the CAL pin experiences the above-mentioned
tCAL_L clock cycles followed by tCAL_H clock cycles.
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CalDly (pin 127) is used to select one of two delay times after the application of power to the start of calibration.
This calibration delay time is depedent on the setting of the CalDly pin and is specified as tCalDly in the Converter
Electrical Characteristics. These delay values allow the power supply to come up and stabilize before calibration
takes place. If the PD pin is high upon power-up, the calibration delay counter will be disabled until the PD pin is
brought low. Therefore, holding the PD pin high during power up will further delay the start of the power-up
calibration cycle. The best setting of the CalDly pin depends upon the power-on settling time of the power supply.
Calibration Operation Notes:
During the calibration cycle, the OR output may be active as a result of the calibration algorithm. All data on
the output pins and the OR output are invalid during the calibration cycle.
During the power-up calibration and during the on-command calibration, all clocks are halted on chip,
including internal clocks and DCLK, while the input termination resistor is trimmed to a value that is equal to
REXT / 33. This is to reduce noise during the input resistor calibration portion of the calibration cycle. See Self
Calibration.
This external resistor is located between pin 32 and ground. REXT must be 3300 ±0.1%. With this value,
the input termination resistor is trimmed to be 100 . Because REXT is also used to set the proper current
for the Track and Hold amplifier, for the preamplifiers and for the comparators, other values of REXT should
not be used.
The CalRun output is high whenever the calibration procedure is running. This is true whether the calibration
is done at power-up or on-command.
Acquiring the Input
Data is acquired at the falling edge of CLK+ (pin 18) and the digital equivalent of that data is available at the
digital outputs 13 input clock cycles later for the DI and DQ output buses and 14 input clock cycles later for the
DId and DQd output buses. There is an additional internal delay called tOD before the data is available at the
outputs. See the Timing Diagram. The ADC08D1500 will convert as long as the input clock signal is present. The
fully differential comparator design and the innovative design of the sample-and-hold amplifier, together with self
calibration, enables a very flat SINAD/ENOB response beyond 1.5 GHz. The ADC08D1500 output data signaling
is LVDS and the output format is offset binary.
Control Modes
Much of the user control can be accomplished with several control pins that are provided. Examples include
initiation of the calibration cycle, power down mode and full scale range setting. However, the ADC08D1500 also
provides an Extended Control mode whereby a serial interface is used to access register-based control of
several advanced features. The Extended Control mode is not intended to be enabled and disabled dynamically.
Rather, the user is expected to employ either the normal control mode or the Extended Control mode at all times.
When the device is in the Extended Control mode, pin-based control of several features is replaced with register-
based control and those pin-based controls are disabled. These pins are OutV (pin 3), OutEdge/DDR (pin 4),
FSR (pin 14) and CalDly/DES (pin 127). See NORMAL/EXTENDED CONTROL for details on the Extended
Control mode.
The Analog Inputs
The ADC08D1500 must be driven with a differential input signal. Operation with a single-ended signal is not
recommended. It is important that the inputs either be a.c. coupled to the inputs with the VCMO pin grounded, or
d.c. coupled with the VCMO pin left floating. An input common mode voltage equal to the VCMO output must be
provided when d.c. coupling is used.
Two full-scale range settings are provided with pin 14 (FSR). The input full-scale range is programmable in the
normal mode by setting a level on pin 14 (FSR) as defined in by the specification VIN in the Converter Electrical
Characteristics. The full-scale range setting operates equally on both ADCs.
In the Extended Control mode, programming the Input Full-Scale Voltage Adjust register allows the input full-
scale range to be adjusted as described in REGISTER DESCRIPTION and THE ANALOG INPUT.
Clocking
The ADC08D1500 must be driven with an a.c. coupled, differential clock signal. THE CLOCK INPUTS describes
the use of the clock input pins. A differential LVDS output clock is available for use in latching the ADC output
data into whatever device is used to receive the data.
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The ADC08D1500 offers two options for output clocking. These options include a choice of which DCLK edge the
output data transitions on and a choice of Single Data Rate (SDR) or Double Data Rate (DDR) outputs.
The ADC08D1500 also has the option to use a duty cycle corrected clock receiver as part of the input clock
circuit. This feature is enabled by default and provides improved ADC clocking. This circuitry allows the ADC to
be clocked with a signal source having a duty cycle ratio of 80 / 20 % (worst case).
Dual-Edge Sampling
The DES mode allows one of the ADC08D1500's inputs (I or Q Channel) to be sampled by both ADCs. One
ADC samples the input on the positive edge of the input clock and the other ADC samples the same input on the
other edge of the input clock. A single input is thus sampled twice per input clock cycle, resulting in an overall
sample rate of twice the input clock frequency, or 3 GSPS with a 1.5 GHz input clock.
In this mode the outputs are interleaved such that the data is effectively demultiplexed 1:4. Since the sample rate
is doubled, each of the 4 output buses have a 750 MHz output rate with a 1.5 GHz input clock. All data is
available in parallel. The four bytes of parallel data that are output with each clock is in the following sampling
order, from the earliest to the latest: DQd, DId, DQ, DI. Table 1 indicates what the outputs represent for the
various sampling possibilities.
In the non-extended mode of operation only the "I" input can be sampled in the DES mode. In the extended
mode of operation the user can select which input is sampled.
The ADC08D1500 also includes an automatic clock phase background calibration feature which can be used in
DES mode to automatically and continuously adjust the clock phase of the I and Q channel. This feature
removes the need to adjust the clock phase setting manually and provides optimal Dual-Edge Sampling ENOB
performance.
NOTE
The background calibration feature in DES mode does not replace the requirement for On-
Command Calibration which should be run before entering DES mode, or if a large swing
in ambient temperature is experienced by the device.
Table 1. Input Channel Samples Produced at Data Outputs
Data Outputs Dual-Edge Sampling Mode (DES)
(Always sourced with Normal Sampling Mode I-Channel Selected Q-Channel Selected (1)
respect to fall of DCLK)
"I" Input Sampled with Fall of "I" Input Sampled with Fall of "Q" Input Sampled with Fall of
DI CLK 13 cycles earlier. CLK 13 cycles earlier. CLK 13 cycles earlier.
"I" Input Sampled with Fall of "I" Input Sampled with Fall of "Q" Input Sampled with Fall of
DId CLK 14 cycles earlier. CLK 14 cycles earlier. CLK 14 cycles earlier.
"Q" Input Sampled with Fall of "I" Input Sampled with Rise of "Q" Input Sampled with Rise of
DQ CLK 13 cycles earlier. CLK 13.5 cycles earlier. CLK 13.5 cycles earlier.
"Q" Input Sampled with Fall of "I" Input Sampled with Rise of "Q" Input Sampled with Rise of
DQd CLK 14 cycles after being CLK 14.5 cycles earlier. CLK 14.5 cycles earlier.
sampled.
(1) In DES + normal mode, only the I Channel is sampled. In DES + extended control mode, I or Q channel can be sampled.
OutEdge Setting
To help ease data capture in the SDR mode, the output data may be caused to transition on either the positive or
the negative edge of the output data clock (DCLK). This is chosen with the OutEdge input (pin 4). A high on the
OutEdge input pin causes the output data to transition on the rising edge of DCLK, while grounding this input
causes the output to transition on the falling edge of DCLK. See Output Edge Synchronization.
Double Data Rate
A choice of single data rate (SDR) or double data rate (DDR) output is offered. With single data rate the output
clock (DCLK) frequency is the same as the data rate of the two output buses. With double data rate the DCLK
frequency is half the data rate and data is sent to the outputs on both edges of DCLK. DDR clocking is enabled
in non-Extended Control mode by allowing pin 4 to float.
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The LVDS Outputs
The data outputs, the Out Of Range (OR) and DCLK, are LVDS. Output current sources provide 3 mA of output
current to a differential 100 Ohm load when the OutV input (pin 3) is high or 2.2 mA when the OutV input is low.
For short LVDS lines and low noise systems, satisfactory performance may be realized with the OutV input low,
which results in lower power consumption. If the LVDS lines are long and/or the system in which the
ADC08D1500 is used is noisy, it may be necessary to tie the OutV pin high.
The LVDS data output have a typical common mode voltage of 800mV when the VBG pin is unconnected and
floating. This common mode voltage can be increased to 1.2V by tying the VBG pin to VAif a higher common
mode is required.
NOTE
Tying the VBG pin to VAwill also increase the differential LVDS output voltage by up to 40
mV.
Power Down
The ADC08D1500 is in the active state when the Power Down pin (PD) is low. When the PD pin is high, the
device is in the power down mode. In this power down mode the data output pins (positive and negative) are
TRI-STATE and the device power consumption is reduced to a minimal level. The DCLK+/- and OR +/- are not at
TRI-STATE. They are weakly pulled down to ground internally. Therefore when both I and Q are powered down
the DCLK +/- and OR +/- should not be terminated to a DC voltage.
A high on the PDQ pin will power down the "Q" channel and leave the "I" channel active. There is no provision to
power down the "I" channel independently of the "Q" channel. Upon return to normal operation, the pipeline will
contain meaningless information.
If the PD input is brought high while a calibration is running, the device will not go into power down until the
calibration sequence is complete. However, if power is applied and PD is already high, the device will not begin
the calibration sequence until the PD input goes low. If a manual calibration is requested while the device is
powered down, the calibration will not begin at all. That is, the manual calibration input is completely ignored in
the power down state. Calibration will function with the "Q" channel powered down, but that channel will not be
calibrated if PDQ is high. If the "Q" channel is subsequently to be used, it is necessary to perform a calibration
after PDQ is brought low.
NORMAL/EXTENDED CONTROL
The ADC08D1500 may be operated in one of two modes. In the simpler standard control mode, the user affects
available configuration and control of the device through several control pins. The "extended control mode"
provides additional configuration and control options through a serial interface and a set of 9 registers. The two
control modes are selected with pin 14 (FSR/ECE: Extended Control Enable). The choice of control modes is
required to be a fixed selection and is not intended to be switched dynamically while the device is operational.
Table 2 shows how several of the device features are affected by the control mode chosen.
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Table 2. Features and Modes
Feature Normal Control Mode Extended Control Mode
Selected with nDE in the Configuration
DDR Clocking selected with pin 4 floating. Register (1h; bit-10). When the device is in
SDR or DDR Clocking SDR clocking selected when pin 4 not DDR mode, address 1h, bit-8 must be set to
floating. 0b.
Selected with DCP in the Configuration
DDR Clock Phase Not Selectable (0° Phase Only) Register (1h; bit-11).
SDR Data transitions with rising edge of
SDR Data transitions with rising or falling Selected with OE in the Configuration
DCLK+ when pin 4 is high and on falling
DCLK edge Register (1h; bit-8).
edge when low.
Normal differential data and DCLK amplitude Selected with the OV in the Configuration
LVDS output level selected when pin 3 is high and reduced Register (1h; bit-9).
amplitude selected when low.
Short delay selected when pin 127 is low and
Power-On Calibration Delay Short delay only.
longer delay selected when high.
Up to 512 step adjustments over a nominal
Normal input full-scale range selected when range specified in REGISTER
Full-Scale Range pin 14 is high and reduced range when low. DESCRIPTION. Selected using the Input
Selected range applies to both channels. Full-Scale Adjust register (3h; bits-7 thru 15).
512 steps of adjustment using the Input
Input Offset Adjust Not possible Offset register (2h; bits-7 thru 15) as
specified in
Dual Edge Sampling Selection Enabled with pin 127 Enabled through DES Enable Register.
Either I- or Q-Channel input may be sampled
Dual Edge Sampling Input Channel Selection Only I-Channel Input can be used by both ADCs.
Automatic Clock Phase control can be
selected by setting bit 14 in the DES Enable
DES Sampling Clock Adjustment The Clock Phase is adjusted automatically Register (Dh). The clock phase can also be
adjusted manually through the Coarse & Fine
Registers (Eh and Fh).
The default state of the Extended Control Mode is set upon power-on reset (internally performed by the device)
and is shown in Table 3.
Table 3. Extended Control Mode Operation
(Pin 14 Floating)
Feature Extended Control Mode Default State
SDR or DDR Clocking DDR Clocking
DDR Clock Phase Data changes with DCLK edge (0° phase)
Normal amplitude
LVDS Output Amplitude (710 mVP-P)
Calibration Delay Short Delay
Full-Scale Range 700 mV nominal for both channels
Input Offset Adjust No adjustment for either channel
Dual Edge Sampling (DES) Not enabled
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THE SERIAL INTERFACE
NOTE
During the initial write using the serial interface, all 8 user registers must be written with
desired or default values. In addition, the first write to the DES Enable register (Dh) must
load the default value (0x3FFFh). Once all registers have been written once, other desired
settings, including enabling DES can be loaded.
The 3-pin serial interface is enabled only when the device is in the Extended Control mode. The pins of this
interface are Serial Clock (SCLK), Serial Data (SDATA) and Serial Interface Chip Select (SCS) Eight write only
registers are accessible through this serial interface.
SCS: This signal should be asserted low while accessing a register through the serial interface. Setup and hold
times with respect to the SCLK must be observed.
SCLK: Serial data input is accepted with the rising edge of this signal. There is no minimum frequency
requirement for SCLK.
SDATA: Each register access requires a specific 32-bit pattern at this input. This pattern consists of a header,
register address and register value. The data is shifted in MSB first. Setup and hold times with respect to the
SCLK must be observed. See the Timing Diagram.
Each Register access consists of 32 bits, as shown in Figure 5 of the Timing Diagrams. The fixed header pattern
is 0000 0000 0001 (eleven zeros followed by a 1). The loading sequence is such that a "0" is loaded first. These
12 bits form the header. The next 4 bits are the address of the register that is to be written to and the last 16 bits
are the data written to the addressed register. The addresses of the various registers are indicated in Table 4.
See REGISTER DESCRIPTION for information on the data to be written to the registers.
Subsequent register accesses may be performed immediately, starting with the 33rd SCLK. This means that the
SCS input does not have to be de-asserted and asserted again between register addresses. It is possible,
although not recommended, to keep the SCS input permanently enabled (at a logic low) when using extended
control.
NOTE
The Serial Interface should not be used when calibrating the ADC. Doing so will impair the
performance of the device until it is re-calibrated correctly. Programming the serial
registers will also reduce dynamic performance of the ADC for the duration of the register
access time.
Table 4. Register Addresses
4-Bit Address
Loading Sequence:
A3 loaded after Fixed Header Pattern, A0 loaded last
A3 A2 A1 A0 Hex Register Addressed
0 0 0 0 0h Reserved
0 0 0 1 1h Configuration
0 0 1 0 2h "I" Ch Offset
0 0 1 1 3h "I" Ch Full-Scale Voltage Adjust
0 1 0 0 4h Reserved
0 1 0 1 5h Reserved
0 1 1 0 6h Reserved
0 1 1 1 7h Reserved
1 0 0 0 8h Reserved
1 0 0 1 9h Reserved
1 0 1 0 Ah "Q" Ch Offset
1 0 1 1 Bh "Q" Ch Full-Scale Voltage Adjust
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Table 4. Register Addresses (continued)
1 1 0 0 Ch Reserved
1 1 0 1 Dh DES Enable
1 1 1 0 Eh DES Coarse Adjust
1 1 1 1 Fh DES Fine Adjust
REGISTER DESCRIPTION
Eight write-only registers provide several control and configuration options in the Extended Control Mode. These
registers have no effect when the device is in the Normal Control Mode. Each register description below also
shows the Power-On Reset (POR) state of each control bit.
Table 5. Configuration Register
Addr: 1h (0001b) W only (0xB2FF)
D15 D14 D13 D12 D11 D10 D9 D8
1 0 1 DCS DCP nDE OV OE
D7 D6 D5 D4 D3 D2 D1 D0
11111111
IMPORTANT: The Configuration Register should not be written if the DES Enable bit = 1. The DES Enable bit should first be changed to 0,
then the Configuration Register can be written. Failure to follow this procedure can cause the internal DES clock generation circuitry to stop.
Bit 15 Must be set to 1b
Bit 14 Must be set to 0b
Bit 13 Must be set to 1b
Bit 12 DCS: Duty Cycle Stabilizer. When this bit is set to 1b , a duty cycle stabilization circuit is applied to the clock
input. When this bit is set to 0b the stabilization circuit is disabled.
POR State: 1b
Bit 11 DCP: DDR Clock Phase. This bit only has an effect in the DDR mode. When this bit is set to 0b, the DCLK
edges are time-aligned with the data bus edges ("0° Phase"). When this bit is set to 1b, the DCLK edges are
placed in the middle of the data bit-cells ("90° Phase"), using the one-half speed DCLK shown in Figure 4 as
the phase reference.
POR State: 0b
Bit 10 nDE: DDR Enable. When this bit is set to 0b, data bus clocking follows the DDR (Double Data Rate) mode
whereby a data word is output with each rising and falling edge of DCLK. When this bit is set to a 1b, data bus
clocking follows the SDR (single data rate) mode whereby each data word is output with either the rising or
falling edge of DCLK , as determined by the OutEdge bit.
POR State: 0b
Bit 9 OV: Output Voltage. This bit determines the LVDS outputs' voltage amplitude and has the same function as the
OutV pin that is used in the normal control mode. When this bit is set to 1b, the standard output amplitude of
710 mVP-P is used. When this bit is set to 0b, the reduced output amplitude of 510 mVP-P is used.
POR State: 1b
Bit 8 OE: Output Edge. This bit selects the DCLK edge with which the data words transition in the SDR mode and
has the same effect as the OutEdge pin in the normal control mode. When this bit is 1, the data outputs change
with the rising edge of DCLK+. When this bit is 0, the data output change with the falling edge of DCLK+.
POR State: 0b
Bits 7:0 Must be set to 1b.
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Table 6. I-Channel Offset
Addr: 2h (0010b) W only (0x007F)
D15 D14 D13 D12 D11 D10 D9 D8
(MSB) Offset Value (LSB)
D7 D6 D5 D4 D3 D2 D1 D0
Sign1111111
Bits 15:8 Offset Value. The input offset of the I-Channel ADC is adjusted linearly and monotonically by the value in this
field. 00h provides a nominal zero offset, while FFh provides a nominal 45 mV of offset. Thus, each code step
provides 0.176 mV of offset.
POR State: 0000 0000 b
Bit 7 Sign bit. 0b gives positive offset, 1b gives negative offset.
POR State: 0b
Bit 6:0 Must be set to 1b
Table 7. I-Channel Full-Scale Voltage Adjust
Addr: 3h (0011b) W only (0x807F)
D15 D14 D13 D12 D11 D10 D9 D8
(MSB) Adjust Value
D7 D6 D5 D4 D3 D2 D1 D0
(LSB) 1 1 1 1 1 1 1
Bit 15:7 Full Scale Voltage Adjust Value. The input full-scale voltage or gain of the I-Channel ADC is adjusted linearly
and monotonically with a 9 bit data value. The adjustment range is ±20% of the nominal 700 mVP-P differential
value.
0000 0000 0 560mVP-P
1000 0000 0 Default Value 700mVP-P
1111 1111 1 840mVP-P
For best performance, it is recommended that the value in this field be limited to the range of 0110 0000 0b to
1110 0000 0b. i.e., limit the amount of adjustment to ±15%. The remaining ±5% headroom allows for the ADC's
own full scale variation. A gain adjustment does not require ADC re-calibration.
POR State: 1000 0000 0b (no adjustment)
Bits 6:0 Must be set to 1b
Table 8. Q-Channel Offset
Addr: Ah (1010b) W only (0x007F)
D15 D14 D13 D12 D11 D10 D9 D8
(MSB) Offset Value (LSB)
D7 D6 D5 D4 D3 D2 D1 D0
Sign1111111
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Bit 15:8 Offset Value. The input offset of the Q-Channel ADC is adjusted linearly and monotonically by the value in this
field. 00h provides a nominal zero offset, while FFh provides a nominal 45 mV of offset. Thus, each code step
provides about 0.176 mV of offset.
POR State: 0000 0000 b
Bit 7 Sign bit. 0b gives positive offset, 1b gives negative offset.
POR State: 0b
Bit 6:0 Must be set to 1b
Table 9. Q-Channel Full-Scale Voltage Adjust
Addr: Bh (1011b) W only (0x807F)
D15 D14 D13 D12 D11 D10 D9 D8
(MSB) Adjust Value
D7 D6 D5 D4 D3 D2 D1 D0
(LSB) 1 1 1 1 1 1 1
Bit 15:7 Full Scale Voltage Adjust Value. The input full-scale voltage or gain of the I-Channel ADC is adjusted linearly
and monotonically with a 9 bit data value. The adjustment range is ±20% of the nominal 700 mVP-P differential
value.
0000 0000 0 560mVP-P
1000 0000 0 700mVP-P
1111 1111 1 840mVP-P
For best performance, it is recommended that the value in this field be limited to the range of 0110 0000 0b to
1110 0000 0b. i.e., limit the amount of adjustment to ±15%. The remaining ±5% headroom allows for the ADC's
own full scale variation. A gain adjustment does not require ADC re-calibration.
POR State: 1000 0000 0b (no adjustment)
Bits 6:0 Must be set to 1b
Table 10. DES Enable
Addr: Dh (1101b) W only (0x3FFF)
D15 D14 D13 D12 D11 D10 D9 D8
DEN ACP 1 1 1 1 1 1
D7 D6 D5 D4 D3 D2 D1 D0
11111111
Bit 15 DES Enable. Setting this bit to 1b enables the Dual Edge Sampling mode. In this mode the ADCs in this device
are used to sample and convert the same analog input in a time-interleaved manner, accomplishing a sample
rate of twice the input clock rate. When this bit is set to 0b, the device operates in the normal dual channel
mode.
POR State: 0b
Bit 14 Automatic Clock Phase (ACP) Control. Setting this bit to 1b enables the Automatic Clock Phase Control. In this
mode the DES Coarse and Fine manual controls are disabled. A phase detection circuit continually adjusts the
I and Q sampling edges to be 180 degrees out of phase. When this bit is set to 0b, the sample (input) clock
delay between the I and Q channels is set manually using the DES Coarse and Fine Adjust registers. (See
Dual Edge Sampling for important application information) Using the ACP Control option is recommended
over the manual DES settings.
POR State: 0b
Bits 13:0 Must be set to 1b
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Table 11. DES Coarse Adjust
Addr: Eh (1110b) W only (0x07FF)
D15 D14 D13 D12 D11 D10 D9 D8
IS ADS CAM 1 1 1
D7 D6 D5 D4 D3 D2 D1 D0
11111111
Bit 15 Input Select. When this bit is set to 0b the "I" input is operated upon by both ADCs. When this bit is set to 1b
the "Q" input is operated on by both ADCs.
POR State: 0b
Bit 14 Adjust Direction Select. When this bit is set to 0b, the programmed delays are applied to the "I" channel sample
clock while the "Q" channel sample clock remains fixed. When this bit is set to 1b, the programmed delays are
applied to the "Q" channel sample clock while the "I" channel sample clock remains fixed.
POR State: 0b
Bits 13:11 Coarse Adjust Magnitude. Each code value in this field delays either the "I" channel or the "Q" channel sample
clock (as determined by the ADS bit) by approximately 20 picoseconds. A value of 000b in this field causes
zero adjustment.
POR State: 000b
Bits 10:0 Must be set to 1b
Table 12. DES Fine Adjust
Addr: Fh (1111b) W only (0x007F)
D15 D14 D13 D12 D11 D10 D9 D8
(MSB) FAM
D7 D6 D5 D4 D3 D2 D1 D0
(LSB) 1 1 1 1 1 1 1
Bits 15:7 Fine Adjust Magnitude. Each code value in this field delays either the "I" channel or the "Q" channel sample
clock (as determined by the ADS bit of the DES Coarse Adjust Register) by approximately 0.1 ps. A value of
0000 0000 0b in this field causes zero adjustment. Note that the amount of adjustment achieved with each
code will vary with the device conditions as well as with the Coarse Adjustment value chosen.
POR State: 0000 0000 0b
Bit 6:0 Must be set to 1b
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Note Regarding Extended Mode Offset Correction
When using the I or Q channel Offset Adjust registers, the following information should be noted.
For offset values of +0000 0000 and -0000 0000, the actual offset is not the same. By changing only the sign bit
in this case, an offset step in the digital output code of about 1/10th of an LSB is experienced. This is shown
more clearly in the Figure below.
Figure 35. Extended Mode Offset Behavior
MULTIPLE ADC SYNCHRONIZATION
The ADC08D1500 has the capability to precisely reset its sampling clock input to DCLK output relationship as
determined by the user-supplied DCLK_RST pulse. This allows multiple ADCs in a system to have their DCLK
(and data) outputs transition at the same time with respect to the shared CLK input that all the ADCs use for
sampling.
The DCLK_RST signal must observe some timing requirements that are shown in Figure 6,Figure 7and Figure 8
of the Timing Diagrams. The DCLK_RST pulse must be of a minimum width and its deassertion edge must
observe setup and hold times with respect to the CLK input rising edge. These timing specifications are listed as
tRH, tRS, and tRPW in the Converter Electrical Characteristics.
The DCLK_RST signal can be asserted asynchronous to the input clock. If DCLK_RST is asserted, the DCLK
output is held in a designated state. The state in which DCLK is held during the reset period is determined by the
mode of operation (SDR/DDR) and the setting of the Output Edge configuration pin or bit. (Refer to
Figure 6,Figure 7 and Figure 8 for the DCLK reset state conditions). Therefore, depending upon when the
DCLK_RST signal is asserted, there may be a narrow pulse on the DCLK line during this reset event. When the
DCLK_RST signal is de-asserted in synchronization with the CLK rising edge, the next CLK falling edge
synchronizes the DCLK output with those of other ADC08D1500s in the system. The DCLK output is enabled
again after a constant delay (relative to the input clock frequency) which is equal to the CLK input to DCLK
output delay (tSD). The device always exhibits this delay characteristic in normal operation.
The DCLK_RST pin should NOT be brought high while the calibration process is running (while CalRun is high).
Doing so could cause a digital glitch in the digital circuitry, resulting in corruption and invalidation of the
calibration.
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Applications Information
THE REFERENCE VOLTAGE
The voltage reference for the ADC08D1500 is derived from a 1.254V bandgap reference, a buffered version of
which is made available at pin 31, VBG, for user convenience. This output has an output current capability of
±100 μA and should be buffered if more current than this is required.
The internal bandgap-derived reference voltage has a nominal value of VIN, as determined by the FSR pin and
described in The Analog Inputs.
There is no provision for the use of an external reference voltage, but the full-scale input voltage can be adjusted
through a Configuration Register in the Extended Control mode, as explained in NORMAL/EXTENDED
CONTROL.
Differential input signals up to the chosen full-scale level will be digitized to 8 bits. Signal excursions beyond the
full-scale range will be clipped at the output. These large signal excursions will also activate the OR output for
the time that the signal is out of range. See Out Of Range (OR) Indication.
One extra feature of the VBG pin is that it can be used to raise the common mode voltage level of the LVDS
outputs. The output offset voltage (VOS) is typically 800mV when the VBG pin is used as an output or left
unconnected. To raise the LVDS offset voltage to a typical value of 1200mV the VBG pin can be connected
directly to the supply rails.
THE ANALOG INPUT
The analog input is a differential one to which the signal source may be a.c. coupled or d.c. coupled. In the
normal mode, the full-scale input range is selected using the FSR pin as specified in the Converter Electrical
Characteristics. In the Extended Control mode, the full-scale input range is selected by programming the Full-
Scale Voltage Adjust register through the Serial Interface. For best performance when adjusting the input full-
scale range in the Extended Control, refer to REGISTER DESCRIPTION. for guidelines on limiting the amount of
adjustment.
Table 13 gives the input to output relationship with the FSR pin high when the normal (non-extended) mode is
used. With the FSR pin grounded, the millivolt values; in are reduced to 75% of the values indicated. In the
Extended Control Mode, these values will be determined by the full scale range and offset settings in the Control
Registers.
Table 13. DIFFERENTIAL INPUT TO OUTPUT RELATIONSHIP
(Non-Extended Control Mode, FSR High)
VIN+ VINOutput Code
VCM 217.5mV VCM + 217.5mV 0000 0000
VCM 109 mV VCM + 109 mV 0100 0000
0111 1111 /
VCM VCM 1000 0000
VCM + 109 mV VCM 109 mV 1100 0000
VCM + 217.5mV VCM 217.5mV 1111 1111
The buffered analog inputs simplify the task of driving these inputs and the RC pole that is generally used at
sampling ADC inputs is not required. If it is desired to use an amplifier circuit before the ADC, use care in
choosing an amplifier with adequate noise and distortion performance and adequate gain at the frequencies used
for the application.
Note that a precise d.c. common mode voltage must be present at the ADC inputs. This common mode voltage,
VCMO, is provided on-chip when a.c. input coupling is used and the input signal is a.c. coupled to the ADC.
When the inputs are a.c. coupled, the VCMO output must be grounded, as shown in Figure 36. This causes the
on-chip VCMO voltage to be connected to the inputs through on-chip 50k-Ohm resistors.
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VIN+
50:
Source
VIN-
1:2 Balun
Ccouple
Ccouple
100:
ADC08D1500
VIN+
VIN-
VCMO
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NOTE
An Analog input channel that is not used (e.g. in DES Mode) should be left floating
when the inputs are a.c. coupled. Do not connect an unused analog input to ground.
Figure 36. Differential Input Drive
When the d.c. coupled mode is used, a common mode voltage must be provided at the differential inputs. This
common mode voltage should track the VCMO output pin. Note that the VCMO output potential will change with
temperature. The common mode output of the driving device should track this change.
NOTE
An analog input channel that is not used (e.g. in DES Mode) should be tied to the
VCMO voltage when the inputs are d.c. coupled. Do not connect unused analog inputs
to ground.
Full-scale distortion performance falls off rapidly as the input common mode voltage deviates from VCMO.
This is a direct result of using a very low supply voltage to minimize power. Keep the input common
voltage within 50 mV of VCMO.
Performance of the ADC08D1500 is as good in the d.c. coupled mode as it is in the a.c. coupled mode,
provided the input common mode voltage at both analog inputs remain within 50 mV of VCMO.
Handling Single-Ended Input Signals
There is no provision for the ADC08D1500 to adequately process single-ended input signals. The best way to
handle single-ended signals is to convert them to differential signals before presenting them to the ADC. The
easiest way to accomplish single-ended to differential signal conversion is with an appropriate balun-connected
transformer, as shown in Figure 37.
A.C. Coupled Input
The easiest way to accomplish single-ended a.c. input to differential a.c. signal is with an appropriate balun-
connected transformer, as shown in Figure 37.
Figure 37. Single-Ended to Differential Signal Conversion Using a Balun
Figure 37 is a generic depiction of a single-ended to differential signal conversion using a balun. The circuitry
specific to the balun will depend on the type of balun selected and the overall board layout. It is recommended
that the system designer contact the manufacturer of the balun they have selected to aid in designing the best
performing single-ended to differential conversion circuit using that particular balun.
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RADJ-
VIN-
VIN+
VCMO
50:
Signal
Input
LMV321
+
-
LMH6555
RADJ+
3.3V
RT2
50:
RT1
50:
RF1
RF2
RG1
RG2
VCM_REF
50:
100:
+
-
50:
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When selecting a balun, it is important to understand the input architecture of the ADC. There are specific balun
parameters of which the system designer should be mindful. They should match the impedance of their analog
source to the ADC08D1500's on-chip 100 differential input termination resistor. The range of this termination
resistor is described in the electrical table as the specification RIN.
Also, as a result of the ADC architecture, the phase and amplitude balance are important. The lowest possible
phase and amplitude imbalance is desired when selecting a balun. The phase imbalance should be no more than
±2.5° and the amplitude imbalance should be limited to less than 1dB at the desired input frequency range.
Finally, when selecting a balun, the VSWR (Voltage Standing Wave Ratio), bandwidth and insertion loss of the
balun should also be considered. The VSWR aids in determining the overall transmission line termination
capability of the balun when interfacing to the ADC input. The insertion loss should be considered so that the
signal at the balun output is within the specified input range of the ADC as described in the Converter Electrical
Characteristics as the specification VIN.
D.C. Coupled Input
When d.c. coupling to the ADC08D1500 analog inputs is required, single-ended to differential conversion may be
easily accomplished with the LMH6555, as shown in Figure 38. In such applications, the LMH6555 performs the
task of single-ended to differential conversion while delivering low distortion and noise, as well as output balance,
that supports the operation of the ADC08D1500. Connecting the ADC08D1500 VCMO pin to the VCM_REF pin of
the LMH6555, through the appropriate buffer, will ensure that the ADC08D1500 common mode input voltage is
as needed for optimum performance of the ADC08D1500. See Figure 38. The LMV321 was chosen as the buffer
in Figure 38 for its low voltage operation and reasonable offset voltage.
Be sure to limit output current from the ADC08D1500 VCMO pin to 100 μA.
Figure 38. Example of Servoing the Analog Input with VCMO
Figure 38,RADJ-and RADJ+ are used to adjust the differential offset that can be measured at the ADC inputs VIN+ /
VIN-. An unadjusted positive offset with reference to VIN-greater than |15mV| should be reduced with a resistor in
the RADJ-position. Likewise, an unadjusted negative offset with reference to VIN-greater than |15mV| should be
reduced with a resistor in the RADJ+ position. gives suggested RADJ-and RADJ+ values for various unadjusted
differential offsets to bring the VIN+ / VIN-offset back to within |15mV|.
Table 14. D.C. Coupled Offset Adjustment
Unadjusted Offset Reading Resistor Value
0mV to 10mV no resistor needed
11mV to 30mV 20.0k
31mV to 50mV 10.0k
51mV to 70mV 6.81k
71mV to 90mV 4.75k
91mV to 110mV 3.92k
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Out Of Range (OR) Indication
When the conversion result is clipped the Out of Range output is activated such that OR+ goes high and OR-
goes low. This output is active as long as accurate data on either or both of the buses would be outside the
range of 00h to FFh.
Full-Scale Input Range
As with all A/D Converters, the input range is determined by the value of the ADC's reference voltage. The
reference voltage of the ADC08D1500 is derived from an internal band-gap reference. The FSR pin controls the
effective reference voltage of the ADC08D1500 such that the differential full-scale input range at the analog
inputs is a normal amplitude with the FSR pin high, or a reduced amplitude with FSR pin low as defined by the
specification VIN in the Converter Electrical Characteristics. Best SNR is obtained with FSR high, but better
distortion and SFDR are obtained with the FSR pin low.
THE CLOCK INPUTS
The ADC08D1500 has differential LVDS clock inputs, CLK+ and CLK-, which must be driven with an a.c.
coupled, differential clock signal. Although the ADC08D1500 is tested and its performance is specified with a
differential 1.5 GHz clock, it typically will function well with input clock frequencies indicated in the Converter
Electrical Characteristic. The clock inputs are internally terminated and biased. The input clock signal must be
capacitively coupled to the clock pins as indicated in Figure 39.
Operation up to the sample rates indicated in the Converter Electrical Characteristic is typically possible if the
maximum ambient temperatures indicated are not exceeded. Operating at higher sample rates than indicated for
the given ambient temperature may result in reduced device reliability and product lifetime. This is because of the
higher power consumption and die temperatures at high sample rates. Important also for reliability is proper
thermal management . See Thermal Management.
Figure 39. Differential (LVDS) Input Clock Connection
The differential input clock line pair should have a characteristic impedance of 100and (when using a balun),
be terminated at the clock source in that (100) characteristic impedance. The input clock line should be as
short and as direct as possible. The ADC08D1500 clock input is internally terminated with an untrimmed 100
resistor.
Insufficient input clock levels will result in poor dynamic performance. Excessively high input clock levels could
cause a change in the analog input offset voltage. To avoid these problems, keep the clock level within the range
specified as VID in the Converter Electrical Characteristics.
The low and high times of the input clock signal can affect the performance of any A/D Converter. The
ADC08D1500 features a duty cycle clock correction circuit which can maintain performance over temperature.
The ADC will meet its performance specification if the input clock high and low times are maintained within the
duty cycle range as specified in the Converter Electrical Characteristics.
High speed, high performance ADCs such as the ADC08D1500 require a very stable input clock signal with
minimum phase noise or jitter. ADC jitter requirements are defined by the ADC resolution (number of bits),
maximum ADC input frequency and the input signal amplitude relative to the ADC input full scale range. The
maximum jitter (the sum of the jitter from all sources) allowed to prevent a jitter-induced reduction in SNR is
found to be
tJ(MAX) = (VINFSR / VIN(P-P)) x (1/(2(N+1) xπx fIN)) (1)
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where tJ(MAX) is the rms total of all jitter sources in seconds, VIN(P-P) is the peak-to-peak analog input signal, VINFSR
is the full-scale range of the ADC, "N" is the ADC resolution in bits and fIN is the maximum input frequency, in
Hertz, to the ADC analog input.
Note that the maximum jitter described above is the RSS sum of the jitter from all sources, including that in the
ADC input clock, that added by the system to the ADC input clock and input signals and that added by the ADC
itself. Since the effective jitter added by the ADC is beyond user control, the best the user can do is to keep the
sum of the externally added input clock jitter and the jitter added by the analog circuitry to the analog signal to a
minimum.
Input clock amplitudes above those specified in the Converter Electrical Characteristics may result in increased
input offset voltage. This would cause the converter to produce an output code other than the expected 127/128
when both input pins are at the same potential.
CONTROL PINS
Six control pins (without the use of the serial interface) provide a wide range of possibilities in the operation of
the ADC08D1500 and facilitate its use. These control pins provide Full-Scale Input Range setting, Self
Calibration, Calibration Delay, Output Edge Synchronization choice, LVDS Output Level choice and a Power
Down feature.
Full-Scale Input Range Setting
Power-on calibration begins after a time delay following the application of power. This time delay is determined
by the setting of CalDly, as described in the Calibration Delay Section, below.
The calibration process will be not be performed if the CAL pin is high at power up. In this case, the calibration
cycle will not begin until the on-command calibration conditions are met. The ADC08D1500 will function with the
CAL pin held high at power up, but no calibration will be done and performance will be impaired. A manual
calibration, however, may be performed after powering up with the CAL pin high. See .
Self Calibration
The ADC08D1500 self-calibration must be run to achieve specified performance. The calibration procedure is run
upon power-up and can be run any time on command. The calibration procedure is exactly the same whether
there is an input clock present upon power up or if the clock begins some time after application of power. The
CalRun output indicator is high while a calibration is in progress. Note that the DCLK outputs are not active
during a calibration cycle, therefore it is not recommended as a system clock.
Power-On Calibration
Power-on calibration begins after a time delay following the application of power. This time delay is determined
by the setting of CalDly, as described in the Calibration Delay Section, below.
The calibration process will be not be performed if the CAL pin is high at power up. In this case, the calibration
cycle will not begin until the on-command calibration conditions are met. The ADC08D1500 will function with the
CAL pin held high at power up, but no calibration will be done and performance will be impaired. A manual
calibration, however, may be performed after powering up with the CAL pin high. See On-Command Calibration.
The internal power-on calibration circuitry comes up in an unknown logic state. If the input clock is not running at
power up and the power on calibration circuitry is active, it will hold the analog circuitry in power down and the
power consumption will typically be less than 200 mW. The power consumption will be normal after the clock
starts.
On-Command Calibration
To initiate an on-command calibration, bring the CAL pin high for a minimum of tCAL_H input clock cycles after it
has been low for a minimum of tCAL_L input clock cycles. Holding the CAL pin high upon power up will prevent
execution of power-on calibration until the CAL pin is low for a minimum of tCAL_L input clock cycles, then brought
high for a minimum of another tCAL_H input clock cycles. The calibration cycle will begin tCAL_H input clock cycles
after the CAL pin is thus brought high. The CalRun signal should be monitored to determine when the calibration
cycle has completed.
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The minimum tCAL_H and tCAL_L input clock cycle sequences are required to ensure that random noise does not
cause a calibration to begin when it is not desired. As mentioned in Self-Calibration for best performance, a self
calibration should be performed 20 seconds or more after power up and repeated when the operating
temperature changes significantly according to the particular system performance requirements. ENOB drops
slightly as junction temperature increases and executing a new self calibration cycle will essentially eliminate the
change.
During a Power-On calibration cycle, both the ADC and the input termination resistor are calibrated. As ENOB
changes slightly with junction temperature, an On-Command calibration can be executed to bring the
performance of the ADC in line.
Calibration Delay
The CalDly input (pin 127) is used to select one of two delay times after the application of power to the start of
calibration, as described in Self-Calibration. The calibration delay values allow the power supply to come up and
stabilize before calibration takes place. With no delay or insufficient delay, calibration would begin before the
power supply is stabilized at its operating value and result in non-optimal calibration coefficients. If the PD pin is
high upon power-up, the calibration delay counter will be disabled until the PD pin is brought low. Therefore,
holding the PD pin high during power up will further delay the start of the power-up calibration cycle. The best
setting of the CalDly pin depends upon the power-on settling time of the power supply.
Note that the calibration delay selection is not possible in the Extended Control mode and the short delay time is
used.
Output Edge Synchronization
DCLK signals are available to help latch the converter output data into external circuitry. The output data can be
synchronized with either edge of these DCLK signals. That is, the output data transition can be set to occur with
either the rising edge or the falling edge of the DCLK signal, so that either edge of that DCLK signal can be used
to latch the output data into the receiving circuit.
When OutEdge (pin 4) is high, the output data is synchronized with (changes with) the rising edge of the DCLK+
(pin 82). When OutEdge is low, the output data is synchronized with the falling edge of DCLK+.
At the very high speeds of which the ADC08D1500 is capable, slight differences in the lengths of the DCLK and
data lines can mean the difference between successful and erroneous data capture. The OutEdge pin is used to
capture data on the DCLK edge that best suits the application circuit and layout.
LVDS Output Level Control
The output level can be set to one of two levels with OutV (pin3). The strength of the output drivers is greater
with OutV high. With OutV low there is less power consumption in the output drivers, but the lower output level
means decreased noise immunity.
For short LVDS lines and low noise systems, satisfactory performance may be realized with the OutV input low.
If the LVDS lines are long and/or the system in which the ADC08D1500 is used is noisy, it may be necessary to
tie the OutV pin high.
Dual Edge Sampling
NOTE
When using the ADC in Extended Control Mode, the Configuration Register must only be
written when the DES Enable bit = 0. Writing to the Configuration Register when the DES
Enable bit = 1 can cause the internal DES clock generation circuitry to stop.
The Dual Edge Sampling (DES) feature causes one of the two input pairs to be routed to both ADCs. The other
input pair is deactivated. One of the ADCs samples the input signal on one input clock edge (duty cycle
corrected), the other samples the input signal on the other input clock edge (duty cycle corrected). The result is a
1:4 demultiplexed output with a sample rate that is twice the input clock frequency.
To use this feature in the non-enhanced control mode, allow pin 127 to float and the signal at the "I" channel
input will be sampled by both converters. The Calibration Delay will then only be a short delay.
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In the enhanced control mode, either input may be used for dual edge sampling. See Power Down.
NOTE
1) For the Extended Control Mode - When using the Automatic Clock Phase Control
feature in dual edge sampling mode, it is important that the automatic phase control is
disabled (set bit 14 of DES Enable register Dh to 0) before the ADC is powered up. Not
doing so may cause the device not to wake-up from the power down state
2) For the Non-Extended Control Mode - When the ADC08D1500 is powered up and DES mode is required,
ensure that pin 127 (CalDly/DES/SCS) is initially pulled low during or after the power up sequence. The pin can
then be allowed to float or be tied to VA/ 2 to enter the DES mode. This will ensure that the part enters the DES
mode correctly.
3) The automatic phase control should also be disabled if the input clock is interrupted or stopped for any reason.
This is also the case if a large abrupt change in the clock frequency occurs.
4) If a calibration of the ADC is required in Auto DES mode, the device must be returned to the Normal Mode of
operation before performing a calibration cycle. Once the Calibration has been completed, the device can be
returned to the Auto DES mode and operation can resume.
Power Down Feature
The Power Down pins (PD and PDQ) allow the ADC08D1500 to be entirely powered down (PD) or the "Q"
channel to be powered down and the "I" channel to remain active. See Power Down for details on the power
down feature.
The digital data (+/-) output pins are put into a high impedance state when the PD pin for the respective channel
is high. Upon return to normal operation, the pipeline will contain meaningless information and must be flushed.
If the PD input is brought high while a calibration is running, the device will not go into power down until the
calibration sequence is complete. However, if power is applied and PD is already high, the device will not begin
the calibration sequence until the PD input goes low. If a manual calibration is requested while the device is
powered down, the calibration will not begin at all. That is, the manual calibration input is completely ignored in
the power down state.
THE DIGITAL OUTPUTS
The ADC08D1500 demultiplexes the output data of each of the two ADCs on the die onto two LVDS output
buses (total of four buses, two for each ADC). For each of the two converters, the results of successive
conversions started on the odd falling edges of the CLK+ pin are available on one of the two LVDS buses, while
the results of conversions started on the even falling edges of the CLK+ pin are available on the other LVDS bus.
This means that, the word rate at each LVDS bus is 1/2 the ADC08D1500 input clock rate and the two buses
must be multiplexed to obtain the entire 1.5 GSPS conversion result.
Since the minimum recommended input clock rate for this device is 200 MSPS (normal non DES mode), the
effective rate can be reduced to as low as 100 MSPS by using the results available on just one of the the two
LVDS buses and a 200 MHz input clock, decimating the 200 MSPS data by two.
There is one LVDS output clock pair (DCLK+/-) available for use to latch the LVDS outputs on all buses. Whether
the data is sent at the rising or falling edge of DCLK is determined by the sense of the OutEdge pin, as described
in Output Edge Synchronization.
DDR (Double Data Rate) clocking can also be used. In this mode a word of data is presented with each edge of
DCLK, reducing the DCLK frequency to 1/4 the input clock frequency. See the Timing Diagram section for
details.
The OutV pin is used to set the LVDS differential output levels. See LVDS Output Level Control.
The output format is Offset Binary. Accordingly, a full-scale input level with VIN+ positive with respect to VINwill
produce an output code of all ones, a full-scale input level with VINpositive with respect to VIN+ will produce an
output code of all zeros and when VIN+ and VINare equal, the output code will vary between codes 127 and
128.
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Linear
Regulator
210
110
100
+
10 PF
+
10 PF
VIN 1.9V
to ADC
+33 PF
ADC08D1500
www.ti.com
SNAS316G JUNE 2005REVISED APRIL 2013
POWER CONSIDERATIONS
A/D converters draw sufficient transient current to corrupt their own power supplies if not adequately bypassed. A
33 µF capacitor should be placed within an inch (2.5 cm) of the A/D converter power pins. A 0.1 µF capacitor
should be placed as close as possible to each VApin, preferably within one-half centimeter. Leadless chip
capacitors are preferred because they have low lead inductance.
The VAand VDR supply pins should be isolated from each other to prevent any digital noise from being coupled
into the analog portions of the ADC. A ferrite choke, such as the JW Miller FB20009-3B, is recommended
between these supply lines when a common source is used for them.
As is the case with all high speed converters, the ADC08D1500 should be assumed to have little power supply
noise rejection. Any power supply used for digital circuitry in a system where a lot of digital power is being
consumed should not be used to supply power to the ADC08D1500. The ADC supplies should be the same
supply used for other analog circuitry, if not a dedicated supply.
Supply Voltage
The ADC08D1500 is specified to operate with a supply voltage of 1.9V ±0.1V. It is very important to note that,
while this device will function with slightly higher supply voltages, these higher supply voltages may reduce
product lifetime.
No pin should ever have a voltage on it that is in excess of the supply voltage or below ground by more than 150
mV, not even on a transient basis. This can be a problem upon application of power and power shut-down. Be
sure that the supplies to circuits driving any of the input pins, analog or digital, do not come up any faster than
does the voltage at the ADC08D1500 power pins.
The Absolute Maximum Ratings should be strictly observed, even during power up and power down. A power
supply that produces a voltage spike at turn-on and/or turn-off of power can destroy the ADC08D1500. The
circuit of Figure 40 will provide supply overshoot protection.
Many linear regulators will produce output spiking at power-on unless there is a minimum load provided. Active
devices draw very little current until their supply voltages reach a few hundred millivolts. The result can be a turn-
on spike that can destroy the ADC08D1500, unless a minimum load is provided for the supply. The 100resistor
at the regulator output provides a minimum output current during power-up to ensure there is no turn-on spiking.
In the circuit of Figure 40, an LM317 linear regulator is satisfactory if its input supply voltage is 4V to 5V . If a
3.3V supply is used, an LM1086 linear regulator is recommended.
Figure 40. Non-Spiking Power Supply
The output drivers should have a supply voltage, VDR, that is within the range specified in the Operating Ratings
table. This voltage should not exceed the VAsupply voltage and should never spike to a voltage greater than (VA
+ 100 mV).
If the power is applied to the device without an input clock signal present, the current drawn by the device might
be below 200 mA. This is because the ADC08D1500 gets reset through clocked logic and its initial state is
unknown. If the reset logic comes up in the "on" state, it will cause most of the analog circuitry to be powered
down, resulting in less than 100 mA of current draw. This current is greater than the power down current
because not all of the ADC is powered down. The device current will be normal after the input clock is
established.
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0.33 mm, typ
0.25 mm, typ
1.2 mm, typ
5.0 mm, min
ADC08D1500
SNAS316G JUNE 2005REVISED APRIL 2013
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Thermal Management
The ADC08D1500 is capable of impressive speeds and performance at very low power levels for its speed.
However, the power consumption is still high enough to require attention to thermal management. For reliability
reasons, the die temperature should be kept to a maximum of 130°C. That is, TA(ambient temperature) plus
ADC power consumption times θJA (junction to ambient thermal resistance) should not exceed 130°C. This is not
a problem if the ambient temperature is kept to a maximum of +85°C as specified in the Operating Ratings
section.
As a convenience to the user, the ADC08D1500 incorporates a thermal diode to aid in temperature
measurement. However, this diode has not been characterized and TI has no information to provide regarding its
characteristics. Hence, no information is available as to the temperature accuracy attainable when using this
diode.
Please note that the following are general recommendations for mounting exposed pad devices onto a PCB. This
should be considered the starting point in PCB and assembly process development. It is recommended that the
process be developed based upon past experience in package mounting.
The package of the ADC08D1500 has an exposed pad on its back that provides the primary heat removal path
as well as excellent electrical grounding to the printed circuit board. The land pattern design for lead attachment
to the PCB should be the same as for a conventional HLQFP, but the exposed pad must be attached to the
board to remove the maximum amount of heat from the package, as well as to ensure best product parametric
performance.
To maximize the removal of heat from the package, a thermal land pattern must be incorporated on the PC
board within the footprint of the package. The exposed pad of the device must be soldered down to ensure
adequate heat conduction out of the package. The land pattern for this exposed pad should be at least as large
as the 5 x 5 mm of the exposed pad of the package and be located such that the exposed pad of the device is
entirely over that thermal land pattern. This thermal land pattern should be electrically connected to ground. A
clearance of at least 0.5 mm should separate this land pattern from the mounting pads for the package pins.
Figure 41. Recommended Package Land Pattern
Since a large aperture opening may result in poor release, the aperture opening should be subdivided into an
array of smaller openings, similar to the land pattern of Figure 41.
To minimize junction temperature, it is recommended that a simple heat sink be built into the PCB. This is done
by including a copper area of about 2 square inches (6.5 square cm) on the opposite side of the PCB. This
copper area may be plated or solder coated to prevent corrosion, but should not have a conformal coating, which
could provide some thermal insulation. Thermal vias should be used to connect these top and bottom copper
areas. These thermal vias act as "heat pipes" to carry the thermal energy from the device side of the board to the
opposite side of the board where it can be more effectively dissipated. The use of 9 to 16 thermal vias is
recommended.
The thermal vias should be placed on a 1.2 mm grid spacing and have a diameter of 0.30 to 0.33 mm. These
vias should be barrel plated to avoid solder wicking into the vias during the soldering process as this wicking
could cause voids in the solder between the package exposed pad and the thermal land on the PCB. Such voids
could increase the thermal resistance between the device and the thermal land on the board, which would cause
the device to run hotter.
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If it is desired to monitor die temperature, a temperature sensor may be mounted on the heat sink area of the
board near the thermal vias. .Allow for a thermal gradient between the temperature sensor and the ADC08D1500
die of θJ-PAD times typical power consumption = 2.8 x 1.8 = 5°C. Allowing for 6°C, including some margin for
temperature drop from the pad to the temperature sensor, then, would mean that maintaining a maximum pad
temperature reading of 124°C will ensure that the die temperature does not exceed 130°C, assuming that the
exposed pad of the ADC08D1500 is properly soldered down and the thermal vias are adequate. (The inaccuracy
of the temperature sensor is additional to the above calculation).
LAYOUT AND GROUNDING
Proper grounding and proper routing of all signals are essential to ensure accurate conversion. A single ground
plane should be used, instead of splitting the ground plane into analog and digital areas.
Since digital switching transients are composed largely of high frequency components, the skin effect tells us that
total ground plane copper weight will have little effect upon the logic-generated noise. Total surface area is more
important than is total ground plane volume. Coupling between the typically noisy digital circuitry and the
sensitive analog circuitry can lead to poor performance that may seem impossible to isolate and remedy. The
solution is to keep the analog circuitry well separated from the digital circuitry.
High power digital components should not be located on or near any linear component or power supply trace or
plane that services analog or mixed signal components as the resulting common return current path could cause
fluctuation in the analog input “ground” return of the ADC, causing excessive noise in the conversion result.
Generally, we assume that analog and digital lines should cross each other at 90° to avoid getting digital noise
into the analog path. In high frequency systems, however, avoid crossing analog and digital lines altogether. The
input clock lines should be isolated from ALL other lines, analog AND digital. The generally accepted 90°
crossing should be avoided as even a little coupling can cause problems at high frequencies. Best performance
at high frequencies is obtained with a straight signal path.
The analog input should be isolated from noisy signal traces to avoid coupling of spurious signals into the input.
This is especially important with the low level drive required of the ADC08D1500. Any external component (e.g.,
a filter capacitor) connected between the converter's input and ground should be connected to a very clean point
in the analog ground plane. All analog circuitry (input amplifiers, filters, etc.) should be separated from any digital
components.
DYNAMIC PERFORMANCE
The ADC08D1500 is a.c. tested and its dynamic performance is specified. To meet the published specifications
and avoid jitter-induced noise, the clock source driving the CLK input must exhibit low rms jitter. The allowable
jitter is a function of the input frequency and the input signal level, as described in THE CLOCK INPUTS .
It is good practice to keep the ADC input clock line as short as possible, to keep it well away from any other
signals and to treat it as a transmission line. Other signals can introduce jitter into the input clock signal. The
clock signal can also introduce noise into the analog path if not isolated from that path.
Best dynamic performance is obtained when the exposed pad at the back of the package has a good connection
to ground. This is because this path from the die to ground is a lower impedance than offered by the package
pins.
USING THE SERIAL INTERFACE
The ADC08D1500 may be operated in the non-extended control (non-Serial Interface) mode or in the extended
control mode. Table 15 and Table 16 describe the functions of pins 3, 4, 14 and 127 in the non-extended control
mode and the extended control mode, respectively.
Non-Extended Control Mode Operation
Non-extended control mode operation means that the Serial Interface is not active and all controllable functions
are controlled with various pin settings. That is, the full-scale range, the power on calibration delay, the output
voltage and the input coupling (a.c. or d.c.). The non-extended control mode is used by setting pin 14 high or
low, as opposed to letting it float. Table 15 indicates the pin functions of the ADC08D1500 in the non-extended
control mode.
Table 15. Non-Extended Control Mode Operation
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Table 15. Non-Extended Control Mode Operation
(Pin 14 High or Low) (continued)
(Pin 14 High or Low)
Pin Low High Floating
3 Reduced VOD Normal VOD n/a
4 OutEdge = Neg OutEdge = Pos DDR
127 CalDly Short CalDly Long DES
14 Reduced VIN Normal VIN Extended Control Mode
Pin 3 can be either high or low in the non-extended control mode. Pin 14 must not be left floating to select this
mode. See NORMAL/EXTENDED CONTROL for more information.
Pin 4 can be high or low or can be left floating in the non-extended control mode. In the non-extended control
mode, pin 4 high or low defines the edge at which the output data transitions. See Output Edge Synchronization
for more information. If this pin is floating, the output clock (DCLK) is a DDR (Double Data Rate) clock (see
Double Data Rate) and the output edge synchronization is irrelevant since data is clocked out on both DCLK
edges.
Pin 127 in the non-extended control mode sets the calibration delay. Pin 127 is not designed to remain floating.
Table 16. Extended Control Mode Operation
(Pin 14 Floating)
Pin Function
3 SCLK (Serial Clock)
4 SDATA (Serial Data)
127 SCS (Serial Interface Chip Select)
COMMON APPLICATION PITFALLS
Failure to write all register locations when using extended control mode. When using the serial interface, all
8 user registers must be written at least once with the default or desired values before calibration and
subsequent use of the ADC. In addition, the first write to the DES Enable register (Dh) must load the default
value (0x3FFFh). Once all registers have been written once, other desired settings, including enabling DES can
be loaded.
Driving the inputs (analog or digital) beyond the power supply rails. For device reliability, no input should go
more than 150 mV below the ground pins or 150 mV above the supply pins. Exceeding these limits on even a
transient basis may not only cause faulty or erratic operation, but may impair device reliability. It is not
uncommon for high speed digital circuits to exhibit undershoot that goes more than a volt below ground.
Controlling the impedance of high speed lines and terminating these lines in their characteristic impedance
should control overshoot.
Care should be taken not to overdrive the inputs of the ADC08D1500. Such practice may lead to conversion
inaccuracies and even to device damage.
Incorrect analog input common mode voltage in the d.c. coupled mode. As discussed in section The Analog
Inputs and THE ANALOG INPUT, the Input common mode voltage must remain within 50 mV of the VCMO
output , which has a variability with temperature that must also be tracked. Distortion performance will be
degraded if the input common mode voltage is more than 50 mV from VCMO .
Using an inadequate amplifier to drive the analog input. Use care when choosing a high frequency amplifier
to drive the ADC08D1500 as many high speed amplifiers will have higher distortion than will the ADC08D1500,
resulting in overall system performance degradation.
Driving the VBG pin to change the reference voltage. As mentioned in THE REFERENCE VOLTAGE, the
reference voltage is intended to be fixed by FSR pin or Full-Scale Voltage Adjust register settings. Over driving
this pin will not change the full scale value, but can otherwise upset operation.
Driving the clock input with an excessively high level signal. The ADC input clock level should not exceed
the level described in the Operating Ratings Table or the input offset could change.
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Inadequate input clock levels. As described in THE CLOCK INPUTS, insufficient input clock levels can result in
poor performance. Excessive input clock levels could result in the introduction of an input offset.
Using a clock source with excessive jitter, using an excessively long input clock signal trace, or having
other signals coupled to the input clock signal trace. This will cause the sampling interval to vary, causing
excessive output noise and a reduction in SNR performance.
Failure to provide adequate heat removal. As described in Thermal Management, it is important to provide
adequate heat removal to ensure device reliability. This can be done either with adequate air flow or the use of a
simple heat sink built into the board. The backside pad should be grounded for best performance.
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REVISION HISTORY
Changes from Revision F (April 2013) to Revision G Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 49
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Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead/Ball Finish
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
ADC08D1500CIYB LIFEBUY HLQFP NNB 128 60 TBD Call TI Call TI -40 to 85 ADC08D1500
CIYB
ADC08D1500CIYB/NOPB NRND HLQFP NNB 128 60 Green (RoHS
& no Sb/Br)
CU SN Level-3-260C-168 HR -40 to 85 ADC08D1500
CIYB
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
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Addendum-Page 2
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MECHANICAL DATA
NNB0128A
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VNX128A (Rev B)
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