12-Bit, 400 MSPS A/D Converter
AD12401
FEATURES
APPLICATIONS
Communications test equipment
Radar and satellite subsystems
Phased array antennas, digital beams
Multichannel, multimode receivers
Secure communications
Wireless and wired broadband communications
Wideband carrier frequency systems
FUNCTIONAL BLOCK DIAGRAM
DATA
READY
A
AD12401
ADC
A
CLK DISTRIBUTION
DA0–DA11
POSTPROCESSING
ADC
B
DR_EN
DATA
READY
B
CLOCK DISTRIBUTION
DIVIDE BY 2
ENC
ENC
OROUT
Figure 1.
GENERAL DESCRIPTION
PRODUCT HIGHLIGHTS
The AD12401 is a 12-bit analog-to-digital converter (ADC)
with a transformer-coupled analog input and digital postprocessing for enhanced SFDR. The product operates at up to
400 MSPS conversion rate with outstanding dynamic performance
in wideband carrier systems.
1. Guaranteed sample rate up to 400 MSPS.
The AD12401 requires a 3.7 V analog supply and 3.3 V and
1.5 V digital supplies, and provides a flexible ENCODE signal
that can be differential or single ended. No external reference is
required.
DB0–DB11
AIN
005649-001
Up to 400 MSPS sample rate
SNR of 63 dBFS @128 MHz
SFDR of 70 dBFS @128 MHz
VSWR of 1:1.5
High or low gain grades
Wideband ac-coupled input signal conditioning
Enhanced spurious-free dynamic range
Single-ended or differential ENCODE signal
LVDS output levels
Twos complement output data
2. Input signal conditioning with optimized dynamic
performance to 175 MHz.
3. High and low gain grades available.
4. Additional performance options available (sample rates
>400 MSPS or second Nyquist zone operation); contact
sales.
5. Proprietary Advanced Filter Bank (AFB™) digital postprocessing from V Corp Technologies, Inc.
The AD12401 package style is an enclosed 2.9" × 2.6" × 0.6"
module. Performance is rated over a 0°C to 60°C case
temperature range.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2006 Analog Devices, Inc. All rights reserved.
AD12401
TABLE OF CONTENTS
Features .............................................................................................. 1
Time-Interleaving ADCs........................................................... 18
Applications....................................................................................... 1
Analog Input ............................................................................... 18
Functional Block Diagram .............................................................. 1
Clock Input.................................................................................. 18
General Description ......................................................................... 1
Digital Outputs ........................................................................... 19
Product Highlights ........................................................................... 1
Power Supplies............................................................................ 19
Revision History ............................................................................... 2
Start-Up and RESET .................................................................. 19
Specifications..................................................................................... 3
DR_EN......................................................................................... 19
DC Specifications ......................................................................... 3
Overrange.................................................................................... 19
AC Specifications—ENCODE = 400 MSPS.............................. 4
Gain Select................................................................................... 20
AC Specifications—ENCODE = 360 MSPS.............................. 5
Thermal Considerations............................................................ 20
AC Specifications—ENCODE = 326 MSPS.............................. 6
Package Integrity/Mounting Guidelines ................................. 20
Absolute Maximum Ratings............................................................ 8
AD12401 Evaluation Kit ........................................................... 21
Explanation of Test Levels ........................................................... 8
Data Outputs............................................................................... 21
ESD Caution.................................................................................. 8
Layout Guidelines........................................................................... 26
Pin Configuration and Function Descriptions........................... 10
PCB Interface .............................................................................. 26
Terminology .................................................................................... 13
Outline Dimensions ....................................................................... 28
Typical Performance Characteristics ........................................... 15
Ordering Guide .......................................................................... 28
Theory of Operation ...................................................................... 18
REVISION HISTORY
4/06—Rev. 0 to Rev. A
Changes to Features and Product Highlights ............................... 1
Changes to Table 1............................................................................ 3
Changes to Table 2............................................................................ 4
Changes to Table 4............................................................................ 6
Changes to Table 7............................................................................ 9
Changes to Figure 5........................................................................ 10
Changes to Table 9.......................................................................... 11
Added Gain Select Section ............................................................ 20
Added H/L_GAIN Section............................................................ 21
Changes to Figure 25...................................................................... 23
Changes to the Ordering Guide.................................................... 28
7/05—Revision 0: Initial Version
Rev. A | Page 2 of 28
AD12401
SPECIFICATIONS
DC SPECIFICATIONS
VA = 3.7 V, VC = 3.3 V, VD = 1.5 V, 0°C ≤ TCASE ≤ 60°C, unless otherwise noted.
Table 1.
Parameter
RESOLUTION
ACCURACY
No Missing Codes
Offset Error
Gain Error @ 10 MHz
Differential Nonlinearity (DNL)
Integral Nonlinearity (INL)
TEMPERATURE DRIFT
Gain Error
ANALOG INPUT (AIN)
Full-Scale Input Voltage Range
Flatness (10 MHz to 175 MHz)
Input VSWR, 50 Ω (300 kHz to 175 MHz)
Analog Input Bandwidth
POWER SUPPLY 1
Supply Voltage
VA
VC
VD
Supply Current
IVA (VA = 3.7 V)
IVC (VC = 3.3 V)
IVD (VD = 1.5 V)
Total Power Dissipation
ENCODE INPUTS
Differential Inputs (ENC, ENC)
Input Voltage
Input Resistance
Input Capacitance
Common-Mode Voltage
Single-Ended Inputs (ENC)
Input Voltage
Input Resistance
LOGIC INPUTS (RESET) 2
Logic 1 Voltage
Logic 0 Voltage
Source IIH
Sink IIL
LOGIC INPUTS (DR_EN)
Logic 1 Voltage
Logic 0 Voltage
Source IIH
Sink IIL
Case Temp
Test Level
Full
Full
Full
60°C
60°C
IV
I
I
V
V
60°C
Min
AD12401-xxxKWS
Typ
Max
12
AD12401-xxxJWS
Min
Typ Max
Unit
Bits
Guaranteed
−12
−10
+12
+10
±0.3
±0.5
±0.3
±0.5
LSB
%FS
LSB
LSB
V
0.02
0.02
%/°C
60°C
Full
60°C
60°C
V
IV
V
V
3.2
0.5
1.5
480
Full
Full
Full
IV
IV
IV
Full
Full
Full
Full
I
I
I
I
Full
60°C
60°C
60°C
IV
V
V
V
0.4
Full
60°C
IV
V
0.4
Full
Full
60°C
60°C
IV
IV
IV
IV
2.0
Full
Full
60°C
60°C
IV
IV
IV
IV
1.7
3.6
3.2
1.45
3.6
3.2
1.45
1.2
500
1.2
6.8
0.95
400
0.8
5.7
1
3.8
3.4
1.55
V
V
V
1.2
500
1.2
6.8
A
mA
A
W
V
Ω
pF
V
100
35
±3
2
0.4
50
2
50
2.0
3.4
0.9
0.8
6
1
20
30
0.7
50
160
V p-p
dB
MHz
0.4
100
35
±3
Rev. A | Page 3 of 28
+12
+10
1.6
0.5
1.5
480
1
3.8
3.4
1.55
0.95
400
0.8
5.7
−12
−10
V p-p
Ω
3.4
0.9
0.8
6
1
V
V
mA
mA
20
30
0.7
50
160
V
V
μA
μA
1.7
AD12401
Parameter
LOGIC OUTPUTS (DRA, DRB, OUTPUT BITS) 3
Differential Output Voltage
Output Common-Mode Voltage
Output High Voltage
Output Low Voltage
1
2
3
AD12401-xxxKWS
Typ
Max
Case Temp
Test Level
Min
Full
Full
60°C
60°C
IV
IV
IV
IV
247
1.125
350
1.25
AD12401-xxxJWS
Min
Typ Max
454
1.375
1.602
0.898
247
1.125
350
1.25
454
1.375
1.602
0.898
Unit
mV
V
V
V
Tested using input frequency of 70 MHz (see Figure 17).
Refer to Table 8 for logic convention on all logic inputs.
Digital output logic levels: VC = 3.3 V, CLOAD = 8 pF, 2.5 V LVDS, RT = 100 Ω.
AC SPECIFICATIONS 1 —ENCODE = 400 MSPS
VA = 3.7 V, VC = 3.3 V, VD = 1.5 V, ENCODE = 400 MSPS, 0°C ≤ TCASE ≤ 60°C, unless otherwise noted.
Table 2.
Parameter
DYNAMIC PERFORMANCE
SNR
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
175 MHz
SINAD 2
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
175 MHz
Spurious-Free Dynamic Range 3
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
175 MHz
Image Spur 4
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
175 MHz
Offset Spur4
Analog Input @ −1.0 dBFS
Two-Tone IMD 5
F1, F2 @ −6 dBFS
ANALOG INPUT
Frequency Range
DIGITAL INPUT (DR_EN)
Minimum Time (Low)
SWITCHING SPECIFICATIONS
Conversion Rate 6
Encode Pulse Width High (tEH)1
Encode Pulse Width Low (tEL)1
Case Temp
Test Level
AD12401-400KWS
Min
Typ
Max
AD12401-400JWS
Min
Typ
Max
Unit
Full
Full
Full
Full
I
I
I
I
62
61.5
60
60
64
63.5
63
62.5
60
59.5
58
57.5
62
61.5
61
60.5
dBFS
dBFS
dBFS
dBFS
Full
Full
Full
Full
I
I
I
I
59
58.5
57.5
55
63.5
63
61.5
60
57
56.5
55.5
53
61.5
61
59.5
58
dBFS
dBFS
dBFS
dBFS
Full
Full
Full
Full
I
I
I
I
69
69
66
62
85
80
72
68
69
69
66
62
85
80
72
68
dBFS
dBFS
dBFS
dBFS
Full
Full
Full
Full
I
I
I
I
60
60
60
57
75
72
66
63
60
60
60
57
75
72
66
63
dBFS
dBFS
dBFS
dBFS
60°C
V
65
65
dBFS
60°C
V
−75
−75
dBc
Full
IV
10
Full
IV
5.0
Full
60°C
60°C
IV
V
V
396
Rev. A | Page 4 of 28
175
10
175
5.0
400
1.25
1.25
404
396
MHz
ns
400
1.25
1.25
404
MSPS
ns
ns
AD12401
Parameter
DIGITAL OUTPUT PARAMETERS
Valid Time (tV)
Propagation Delay (tPD)
Rise Time, tR (20% to 80%)
Fall Time, tF (20% to 80%)
DR Propagation Delay (tEDR)
Data to DR Skew (tEDR − tPD)
Pipeline Latency 7
Start-Up Time
Postprocessing Configuration Time
APERTURE DELAY (tA)
APERTURE UNCERTAINTY (Jitter, tJ)
Case Temp
Test Level
Full
60°C
60°C
60°C
60°C
60°C
Full
Full
Full
60°C
60°C
IV
V
V
V
V
V
IV
IV
IV
V
V
AD12401-400KWS
Min
Typ
Max
AD12401-400JWS
Min
Typ
Max
3.9
8.7
0.3
0.3
11.2
2.5
74
44
2.8
2.3
0.4
3.9
8.7
0.3
0.3
11.2
2.5
74
44
2.8
2.3
0.4
29
87
29
Unit
ns
ns
ns
ns
ns
ns
Cycles
ms
sec
ns
ps rms
87
All ac specifications tested with a single-ended, 2.0 V p-p encode on ENCODE and ENCODE floating.
The image spur is included in the SINAD measurement.
3
The image spur is not included in the SFDR specification.
4
The image spur is at fS/2 – AIN; the offset spur is at fS/2.
5
F1 = 70 MHz, F2 = 73 MHz.
6
Parts are tested with 400 MSPS encode. Device can be clocked at lower encode rates, but specifications are not guaranteed. Specifications are guaranteed by design
for encode 400 MSPS ± 1%.
7
Pipeline latency is exactly 74 cycles with an additional tPD required for data to emerge.
1
2
AC SPECIFICATIONS 1 —ENCODE = 360 MSPS
VA = 3.7 V, VC = 3.3 V, VD = 1.5 V, encode = 360 MSPS, 0°C ≤ TCASE ≤ 60°C, unless otherwise noted.
Table 3.
Parameter
DYNAMIC PERFORMANCE
SNR
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
SINAD 2
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
Spurious-Free Dynamic Range 3
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
Image Spur 4
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
Offset Spur4
Analog Input @ −1.0 dBFS
Two-Tone IMD 5
F1, F2 @ −6 dBFS
ANALOG INPUT
Frequency Range
DIGITAL INPUT (DR_EN)
Minimum Time (Low)
AD12401-360KWS
Typ
Max
Case Temp
Test Level
Min
Full
Full
Full
I
I
I
62
61.5
60
64
63.5
63
dBFS
dBFS
dBFS
Full
Full
Full
I
I
I
59
58.5
57.5
63.5
63
61.5
dBFS
dBFS
dBFS
Full
Full
Full
I
I
I
69
69
66
85
80
72
dBFS
dBFS
dBFS
Full
Full
Full
I
I
I
60
60
60
75
72
66
dBFS
dBFS
dBFS
60°C
V
65
dBFS
60°C
V
−75
dBc
Full
IV
10
Full
IV
5.6
Rev. A | Page 5 of 28
160
Unit
MHz
ns
AD12401
Parameter
SWITCHING SPECIFICATIONS
Conversion Rate 6
Encode Pulse Width High (tEH)1
Encode Pulse Width Low (tEL)1
DIGITAL OUTPUT PARAMETERS
Valid Time (tV)
Propagation Delay (tPD)
Rise Time, tR (20% to 80%)
Fall Time, tF (20% to 80%)
DR Propagation Delay (tEDR)
Data to DR Skew (tEDR − tPD)
Pipeline Latency 7
Start-Up Time
Postprocessing Configuration Time
APERTURE DELAY (tA)
APERTURE UNCERTAINTY (Jitter, tJ)
Case Temp
Test Level
Min
Full
60°C
60°C
IV
V
V
356
Full
60°C
60°C
60°C
60°C
60°C
Full
Full
Full
60°C
60°C
IV
V
V
V
V
V
IV
IV
IV
V
V
AD12401-360KWS
Typ
Max
29
360
1.38
1.38
364
4.5
8.7
0.3
0.3
11.5
2.8
74
44
87
3.1
2.3
0.4
Unit
MSPS
ns
ns
ns
ns
ns
ns
ns
ns
Cycles
ms
sec
ns
ps rms
All ac specifications tested with a single-ended, 2.0 V p-p encode on ENCODE and ENCODE floating.
The image spur is included in the SINAD specification.
The image spur is not included in the SFDR specification.
4
The image spur is at fS/2 – AIN; the offset spur is at fS/2.
5
F1 = 70 MHz, F2 = 73 MHz.
6
Parts are tested with 360 MSPS encode. Device can be clocked at lower encode rates, but specifications are not guaranteed. Specifications are guaranteed by design
for encode 360 MSPS ± 1%.
7
Pipeline latency is exactly 74 cycles with an additional tPD required for data to emerge.
1
2
3
AC SPECIFICATIONS 1 —ENCODE = 326 MSPS
VA = 3.7 V, VC = 3.3 V, VD = 1.5 V, ENCODE = 326 MSPS, 0°C ≤ TCASE ≤ 60°C, unless otherwise noted.
Table 4.
Parameter
DYNAMIC PERFORMANCE
SNR
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
SINAD 2
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
Spurious-Free Dynamic Range 3
Analog Input 10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
Image Spur 4
Analog Input
10 MHz
@ −1.0 dBFS
70 MHz
128 MHz
Offset Spur5
Analog Input @ −1.0 dBFS
Two-Tone IMD 5
F1, F2 @ −6 dBFS
Case Temp
Test Level
AD12401-326KWS
Min
Typ
Max
AD12401-326JWS
Min
Typ
Max
Unit
Full
Full
Full
I
I
I
62
61.5
60
64
63.5
63
60
59.5
58
62
61.5
61
dBFS
dBFS
dBFS
Full
Full
Full
I
I
I
59
58.5
57.5
63.5
63
61.5
57
56.5
55.5
61.5
61
59.5
dBFS
dBFS
dBFS
Full
Full
Full
I
I
I
69
69
66
85
80
72
69
69
66
85
80
72
dBFS
dBFS
dBFS
Full
Full
Full
I
I
I
60
60
60
75
72
66
60
60
60
75
72
66
dBFS
dBFS
dBFS
60°C
V
65
65
dBFS
60°C
V
−75
−75
dBc
Rev. A | Page 6 of 28
AD12401
Parameter
ANALOG INPUT
Frequency Range
DIGITAL INPUT (DR_EN)
Minimum Time (Low)
SWITCHING SPECIFICATIONS
Conversion Rate 6
Encode Pulse Width High (tEH)1
Encode Pulse Width Low (tEL)1
DIGITAL OUTPUT PARAMETERS
Valid Time (tV)
Propagation Delay (tPD)
Rise Time, tR (20% to 80%)
Fall Time, tF (20% to 80%)
DR Propagation Delay (tEDR)
Data to DR Skew (tEDR − tPD)
Pipeline Latency 7
Start-Up Time
Postprocessing Configuration Time
APERTURE DELAY (tA)
APERTURE UNCERTAINTY (Jitter, tJ)
Case Temp
Test Level
AD12401-326KWS
Min
Typ
Max
AD12401-326JWS
Min
Typ
Max
Unit
Full
IV
10
10
MHz
Full
IV
6.2
Full
60°C
60°C
IV
V
V
323
Full
60°C
60°C
60°C
60°C
60°C
Full
Full
Full
60°C
60°C
IV
V
V
V
V
V
IV
IV
IV
V
V
29
140
140
6.2
326
1.53
1.53
5.0
8.7
0.3
0.3
11.8
3.1
74
44
2.3
0.4
329
87
3.4
323
29
ns
326
1.53
1.53
5.0
8.7
0.3
0.3
11.8
3.1
74
44
2.3
0.4
329
87
3.4
MSPS
ns
ns
ns
ns
ns
ns
ns
ns
Cycles
ms
sec
ns
ps rms
All ac specifications tested with a single-ended, 2.0 V p-p encode on ENCODE and ENCODE floating.
The image spur is included in the SINAD measurement.
3
The image spur is not included in the SFDR specification.
4
The image spur is at fS/2 − AIN; the offset spur is at fS/2.
5
F1 = 70 MHz, F2 = 73 MHz.
6
Parts are tested with 326 MSPS encode. Device can be clocked at lower encode rates, but specifications are not guaranteed. Specifications are guaranteed by design
for encode 326 MSPS ±1%.
7
Pipeline latency is exactly 74 cycles with an additional tPD required for data to emerge.
1
2
Rev. A | Page 7 of 28
AD12401
ABSOLUTE MAXIMUM RATINGS
Table 5.
Parameter
VA to AGND
VC to DGND
VD to DGND
Analog Input Voltage
Analog Input Power
ENCODE Input Voltage
ENCODE Input Power
Logic Inputs
Storage Temperature Range, Ambient
Operating Temperature Range
Value
5V
4V
1.6 V max
6 V (dc)
18 dBm (ac)
6 V (dc)
12 dBm (ac)
−0.3 V to +4 V
−65°C to +150°C
0°C to 60°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
EXPLANATION OF TEST LEVELS
Table 6.
Level
I
II
III
IV
V
VI
Description
100% production tested.
100% production tested at 25°C and sample tested at specified temperatures.
Sample tested only.
Parameter is guaranteed by design and characterization testing.
Parameter is a typical value only.
100% production tested at 25°C; guaranteed by design and characterization testing for industrial temperature range; 100%
production tested at temperature extremes for military devices.
ESD CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on
the human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. A | Page 8 of 28
AD12401
Table 7. Output Coding (Twos Complement)
KWS
+1.6
.
.
.
0
−0.000781 to
.
.
−1.6 to
AIN (V)
JWS
+0.8
.
.
.
0
+0.0003905
.
.
+0.8
Digital Output
0111 1111 1111
.
.
.
0000 0000 0000
1111 1111 1111
.
.
1000 0000 0000
Pin
Name
RESET
DR_EN
Logic
Level
Type
LVTTL
LVTTL
Active
High
Low
High
Default
Level
High
High
Associated Circuitry
Within Part
3.74 kΩ Pull-Up
Weak Pull-Up (>16 kΩ)
3.3V
100Ω
ENCODE
3.3V
100Ω
100Ω
PECL
DRIVER
05649-002
ENCODE
100Ω
Figure 2. ENCODE Equivalent Circuit
N–1
N
N+1
N+2
N+3
tEL
tEH
1/fS
ENC
400MHZ
74 CLOCK CYCLES
N – 74
DATA OUT A
1
N
N – 73
N+4
N+2
N+6
N+8
DRA
DRA
1
N+1
DATA OUT B
N+3
N+5
N+7
DRB
DRB
NOTES
1. DATA LOST DUE TO ASSERTION OF DR_EN. LATENCY OF 74 ENCODE CLOCK CYCLES BEFORE DATA VALID.
2. IF A SINGLE-ENDED SINE WAVE IS USED FOR ENCODE, USE THE ZERO CROSSING POINT (AC-COUPLED) AS
THE 50% POINT AND APPLY THE SAME TIMING INFORMATION.
3. THE DR_EN PIN IS USED TO SYNCHRONIZE THE COLLECTION OF DATA INTO EXTERNAL BUFFER MEMORIES.
THE DR_EN PIN CAN BE APPLIED SYNCHRONOUSLY OR ASYNCHRONOUSLY TO THE AD12401. IF APPLIED
ASYNCHRONOUSLY, DR_EN MUST BE HELD LOW FOR A MINIMUM OF 5ns TO ENSURE CORRECT OPERATION.
THE FUNCTION SHUTS OFF DRA AND DRB UNTIL THE DR_EN PIN IS SET HIGH AGAIN. DRA AND DRB RESUME
ON THE NEXT VALID DRA AFTER DR_EN IS RETURNED HIGH. IF THIS FEATURE IS NOT REQUIRED, TIE THIS
PIN TO 3.3V THROUGH A 3.74kΩ RESISTOR OR LEAVE IT FLOATING.
Figure 3. Timing Diagram
tEDR
ENC
ENC
tPD
tVD
DATA OUT
DR
DR
Figure 4. Highlighted Timing Diagram
Rev. A | Page 9 of 28
05649-003
DR_EN
05649-004
Code
4095
.
.
.
2048
2047
.
.
0
Table 8. Option Pin List with Necessary Associated Circuitry
AD12401
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
PIN 119
ENC
ENC
TOP VIEW
VA
VA
VA
VA
AGND
AGND
DNC
DNC
H/L_GAIN
DNC
DNC
DNC
AGND
AGND
AGND
AGND
AGND
AGND
AGND
AGND
JOHNSON SMA-50 Ω CONNECT NO. 142-0711-821
PIN 79
2-56 STUDS 4⋅
END VIEW
SAMTEC CONNECTOR
QTE-060-01-L-D-A-K-TR
BOARD
ENC
ENC
PIN 39
AIN
BOTTOM VIEW
LEFT SIDE VIEW
NOTE:
1. FOR MATING CONNECTOR, USE SAMTEC, INC.
PART NO. QSE-60-01-L-D-A-K.
INTEGRAL GROUND PLANE CONNECTIONS.
SECTION A = DGND, PINS 121–124.
SECTION B = DGND, PINS 125–128.
SECTION C = AGND, PINS 129–132.
PIN 1
Figure 5. Pin Configuration
Rev. A | Page 10 of 28
DNC
DR_EN
DA1
DA1
DA3
DA3
DA5
DA5
DA7
DA7
DA9
DA9
DA11
DA11
DNC
DNC
VD
VD
VD
VD
DB1
DB1
DB3
DB3
DB5
DB5
DB7
DB7
DB9
DB9
DB11
DB11
DNC
DNC
DNC
DNC
DNC
RESET
VC
VC
1
VA
VA
VA
VA
AGND
AGND
DNC
DNC
DNC
DNC
DNC
DNC
DNC
AGND
AGND
AGND
AGND
AGND
AGND
AGND
PIN 120
DRA
DRA
DA0
DA0
DA2
DA2
DA4
DA4
DA6
DA6
DA8
DA8
DA10
DA10
DNC
DNC
VD
VD
VD
VD
PIN 80
DB0
DB0
DB2
DB2
DB4
DB4
DB6
DB6
DB8
DB8
DB10
DB10
OROUT
OROUT
DRB
DRB
DNC
DNC
VC
VC
PIN 40
C
1
1
B
A
PIN 2
05649-005
PIN 1
AIN
AD12401
Table 9. Pin Function Descriptions
Pin No.
1 to 4
5
6 to 9, 11, 13 ,15,
49 to 52, 79, 96 to
102, 104 to108
10
12
14
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41 to 48
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
Mnemonic
VC
RESET
DNC
Description
Digital Supply, 3.3 V.
LVTTL. 0 = device reset. Minimum width = 200 ns. Device resumes operation after 600 ms maximum.
Do Not Connect.
DRB
DRB
OROUT
OROUT
DB11
DB10
DB11
DB10
DB9
DB8
DB9
DB8
DB7
DB6
DB7
DB6
DB5
DB4
DB5
DB4
DB3
DB2
DB3
DB2
DB1
DB0
DB1
DB0
VD
DA11
DA10
DA11
DA10
DA9
DA8
DA9
DA8
DA7
DA6
DA7
DA6
DA5
DA4
DA5
DA4
Channel B Data Ready. Complement output.
Channel B Data Ready. True output.
Overrange. Complement output.
Overrange. True Output 1 = overranged, 0 = normal operation.
Channel B Data Bit 11. Complement output bit.
Channel B Data Bit 10. Complement output bit.
Channel B Data Bit 11. True output bit.
Channel B Data Bit 10. True output bit.
Channel B Data Bit 9. Complement output bit.
Channel B Data Bit 8. Complement output bit.
Channel B Data Bit 9. True output bit.
Channel B Data Bit 8. True output bit.
Channel B Data Bit 7. Complement output bit.
Channel B Data Bit 6. Complement output bit.
Channel B Data Bit 7. True output bit.
Channel B Data Bit 6. True output bit.
Channel B Data Bit 5. Complement output bit.
Channel B Data Bit 4. Complement output bit.
Channel B Data Bit 5. True output bit.
Channel B Data Bit 4. True output bit.
Channel B Data Bit 3. Complement output bit.
Channel B Data Bit 2. Complement output bit.
Channel B Data Bit 3. True output bit.
Channel B Data Bit 2. True output bit.
Channel B Data Bit 1. Complement output bit.
Channel B Data Bit 0. Complement output bit. DB0 is LSB.
Channel B Data Bit 1. True output bit.
Channel B Data Bit 0. True output bit. DB0 is LSB.
Digital Supply, 1.5 V.
Channel A Data Bit 11. Complement output bit.
Channel A Data Bit 10. Complement output bit.
Channel A Data Bit 11. True output bit.
Channel A Data Bit 10. True output bit.
Channel A Data Bit 9. Complement output bit.
Channel A Data Bit 8. Complement output bit.
Channel A Data Bit 9. True output bit.
Channel A Data Bit 8. True output bit.
Channel A Data Bit 7. Complement output bit.
Channel A Data Bit 6. Complement output bit.
Channel A Data Bit 7. True output bit.
Channel A Data Bit 6. True output bit.
Channel A Data Bit 5. Complement output bit.
Channel A Data Bit 4. Complement output bit.
Channel A Data Bit 5. True output bit.
Channel A Data Bit 4. True output bit.
Rev. A | Page 11 of 28
AD12401
Pin No.
69
70
71
72
73
74
75
76
77
78
80
103
81 to 95, 109 to 112,
129 to 132 1
113 to 120
121 to 1281
1
Mnemonic
DA3
DA2
DA3
DA2
DA1
DA0
DA1
DA0
DR_EN
DRA
DRA
H/L GAIN
AGND
Description
Channel A Data Bit 3. Complement output bit.
Channel A Data Bit 2. Complement output bit.
Channel A Data Bit 3. True output bit.
Channel A Data Bit 2. True output bit.
Channel A Data Bit 1. Complement output bit.
Channel A Data Bit 0. Complement output bit. DA0 is LSB.
Channel A Data Bit 1. True output bit.
Channel A Data Bit 0. True output bit. DA0 is LSB.
Data Ready Enable, Typically DNC. See the DR_EN section.
Channel A Data Ready. Complement output.
Channel A Data Ready. True output.
Gain Select Pin. Ground for low gain mode (KWS); pull up to 3.3 V for high gain mode (JWS).
Analog Ground.
VA
DGND
Analog Supply, 3.7 V.
Digital Ground.
Internal ground plane connections: Section A = DGND, Pin 121 to Pin 124; Section B = DGND, Pin 125 to Pin 128; Section C = AGND, Pin 129 to Pin 132.
Rev. A | Page 12 of 28
AD12401
TERMINOLOGY
Analog Bandwidth
The analog input frequency at which the spectral power of the
fundamental frequency (as determined by the FFT analysis) is
reduced by 3 dB.
Full-Scale Input Power
Expressed in dBm. Computed using the equation
POWERFull-Scale = 10 log ((V2Full-Scalerms)/(|ZINPUT| × 0.001))
Aperture Delay
The delay between the 50% point on the rising edge of the
ENCODE command and the instant at which the analog input
is sampled.
Full-Scale Input Voltage Range
The maximum peak-to-peak input signal magnitude that results
in a full-scale response, 0 dBFS on a single-tone input signal
case. Any magnitude increase from this value results in an
overrange condition.
Analog Input VSWR (50 Ω)
VSWR is a ratio of the transmitted and reflected signals. The
VSWR can be related to input impedance.
Gain Error
The difference between the measured and ideal full-scale input
voltage range of the ADC.
Γ = (ZL − ZS)/(ZL + ZS)
Harmonic Distortion, Second
The ratio of the rms signal amplitude to the rms value of the
second harmonic component, reported in dBFS.
where:
ZL = actual load impedance.
ZS = reference impedance.
Harmonic Distortion, Third
The ratio of the rms signal amplitude to the rms value of the
third harmonic component, reported in dBFS.
VSWR = (1 − |Γ|)/(1 +|Γ|)
Aperture Uncertainty (Jitter)
The sample-to-sample variation in aperture delay.
Integral Nonlinearity
The deviation of the transfer function from a reference line
measured in fractions of 1 LSB using a best straight line
determined by a least square curve fit.
Differential Nonlinearity
The deviation of any code width from an ideal 1 LSB step.
Distortion, Image Spur
The ratio of the rms signal amplitude to the rms signal amplitude of the image spur, reported in dBFS. The image spur, a
result of gain and phase errors between two time-interleaved
conversion channels, is located at fS/2 − fAIN.
Distortion, Offset Spur
The ratio of the rms signal amplitude to the rms signal amplitude of the offset spur, reported in dBFS. The offset spur, a
result of offset errors between two time-interleaved conversion
channels, is located at fS/2.
Minimum Conversion Rate
The minimum ENCODE rate at which the image spur calibration
degrades no more than 1 dB (when the image spur is 70 dB).
Offset Error
The dc offset imposed on the input signal by the ADC, reported
in LSB (codes).
Output Propagation Delay
The delay between a differential crossing of ENCODE and
ENCODE (or zero crossing of a single-ended ENCODE).
Effective Number of Bits (ENOB)
Calculated from the measured SNR based on the equation
ENOB =
Maximum Conversion Rate
The maximum ENCODE rate at which the image spur calibration
degrades no more than 1 dB (when the image spur is 70 dB).
SNRMEASURED − 1.76 dB
6.02
ENCODE Pulse Width/Duty Cycle
Pulse width high is the minimum amount of time the ENCODE
pulse should be left in Logic 1 state to achieve rated performance; pulse width low is the minimum time the ENCODE pulse
should be left in low state.
Pipeline Latency
The number of clock cycles the output data lags the corresponding clock cycle.
Power Supply Rejection Ratio (PSRR)
The ratio of power supply voltage change to the resulting ADC
output voltage change.
Rev. A | Page 13 of 28
AD12401
Signal-to-Noise-and-Distortion (SINAD)
The ratio of the rms signal amplitude (set 1 dB below full scale)
to the rms value of the sum of all other spectral components,
including harmonics, but excluding dc and image spur.
Signal-to-Noise Ratio (SNR)
The ratio of the rms signal amplitude (set at 1 dB below full
scale) to the rms value of the sum of all other spectral components, excluding the first five harmonics and dc.
Spurious-Free Dynamic Range (SFDR)
The ratio of the rms signal amplitude to the rms value of the
peak spurious spectral component, except the image spur. The
peak spurious component may or may not be a harmonic. It can
be reported in dBc (that is, degrades as signal level is lowered)
or dBFS (always related back to converter full-scale).
Total Noise
Calculated as
− SignaldBFS
( FSdBm − SNRdBc
)
10
VNOISE = Z × 0.001 × 10
where:
Z is the input impedance.
FS is the full scale of the device for the frequency in question.
SNR is the value of the particular input level.
Signal is the signal level within the ADC reported in dB below
full scale. This value includes both thermal and quantization noise.
Two-Tone Intermodulation Distortion Rejection
The ratio of the rms value of either input tone to the rms value
of the worst third-order intermodulation product; reported in dBc.
Two-Tone SFDR
The ratio of the rms value of either input tone to the rms value
of the peak spurious component. The peak spurious component
may or may not be an IMD product. It can be reported in dBc
(that is, degrades as signal level is lowered) or in dBFS (always
related back to converter full-scale).
Rev. A | Page 14 of 28
AD12401
TYPICAL PERFORMANCE CHARACTERISTICS
0
0
1
SNR = 63.26dB
SFDR = 76.77dBc
SINAD = 62.97dB
IMAGE SPUR = –76.69dBc
–10
–20
–30
–30
–40
–40
–50
–50
dB
–60
–60
–70
–70
2
X
2
3
–90
–80
N
5
6
–100
–110
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
1
–10
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
200
Figure 9. FFT: fS = 400 MSPS, AIN = 175.123 MHz @ –1.0 dBFS;
X = Image Spur, N = Interleaved Offset Spur
0
SNR = 62.61dB
SFDR = 78.03dBc
SINAD = 62.41dB
IMAGE SPUR = –86.28dBc
12
–10
–20
–30
–30
–40
–40
–50
–50
3
X
–80
–90
05649-007
4
–100
–110
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
05649-010
5
6
–100
–110
0
200
20
Figure 7. FFT: fS = 400 MSPS, AIN = 70.123 MHz @ –1.0 dBFS;
X = Image Spur, N = Interleaved Offset Spur
0
–20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
200
Figure 10. Two-Tone Intermodulation Distortion
(25.1 MHz and 28.1 MHz; fS = 400 MSPS);
X = Image Spur, N = Interleaved Offset Spur
0
1
SNR = 61.54dB
SFDR = 74.03dBc
SINAD = 60.92dB
IMAGE SPUR = –75.09dBc
–10
2F1 + F2
2F2 + F1
–90
F2 + F1
–80
N
2F2 – F1
2
F2 – F1
–70
–70
2F1 – F2
–60
–60
12
–10
–20
–30
–40
–40
–50
–50
dB
–30
N
6
4
–80
5
–90
–100
–110
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
05649-011
–90
2F2 + F1
2F1 + F2
–70
2
X
2F1 – F2
3
–80
F2 + F1
–70
F2 + F1
–60
–60
05649-008
dB
6
–110
200
dB
dB
–20
4
–100
Figure 6. FFT: fS = 400 MSPS, AIN = 10.123 MHz @ –1.0 dBFS;
X = Image Spur, N = Interleaved Offset Spur
0
N
5
–90
05649-006
4
3
X
05649-009
–80
2F2 – F1
dB
–20
1
SNR = 60.74dB
SFDR = 71.57dBc
SINAD = 60.29dB
IMAGE SPUR = –82.52dBc
–10
–100
–110
0
200
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
Figure 11. Two-Tone Intermodulation Distortion
(70.1 MHz and 73.1 MHz; fS = 400 MSPS);
X = Image Spur, N = Interleaved Offset Spur
Figure 8. FFT: fS = 400 MSPS, AIN = 128.123 MHz @ –1.0 dBFS;
X = Image Spur, N = Interleaved Offset Spur
Rev. A | Page 15 of 28
200
AD12401
0
95
12
–10
IMAGE SPUR
90
–20
THIRD HARMONIC
–30
HARMONICS (dBc)
85
–40
2F1 – F2
–80
2F1 + F2
2F2 + F1
–70
F2 + F1
F2 – F1
–60
2F2 – F1
dB
–50
80
75
SECOND HARMONIC
70
–90
–110
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
05649-042
65
05649-012
–100
60
0
200
63.5
0.2
63.0
0.1
0
–0.1
60.5
–0.4
157
181
140
160
180
61.5
–0.3
132
120
62.0
61.0
108
100
62.5
–0.2
83.6
80
205
05649-016
SNR (dBFS)
64.0
0.3
05649-040
GAIN (dB)
64.5
0.4
59.3
60
Figure 15. Harmonics vs. Analog Input Frequency
0.5
35.0
40
ANALOG INPUT FREQUENCY (MHz)
Figure 12. Two-Tone Intermodulation Distortion
(172.1 MHz and 175.1 MHz; fS = 400 MSPS), SFDR = 70 dBc;
X = Image Spur, N = Interleaved Offset Spur
–0.5
10.7
20
60.0
59.5
229
0
50
100
150
200
ANALOG INPUT FREQUENCY (MHz)
FREQUENCY (MHz)
Figure 16. SNR vs. Analog Input Frequency
Figure 13. Interleaved Gain Flatness
1.0
100
THIRD HARMONIC
95
VD SUPPLY CURRENT (A)
0.9
85
SECOND HARMONIC
80
IMAGE SPUR
75
70
60
0
10
20
30
40
50
ANALOG INPUT LEVEL (dB)
60
0.7
0.6
0.5
0.4
05649-041
65
0.8
0.3
70
05649-017
DISTORTION (dBFS)
90
0
20
40
60
80
100
120
140
160
180
INPUT FREQUENCY (MHz)
Figure 14. Second/Third Harmonics and Image Spur vs. Analog Input Level;
fS = 400 MSPS, AIN = 70 MHz
Rev. A | Page 16 of 28
Figure 17. VD Supply Current vs. AIN Frequency
200
AD12401
–1.00
–1.42
–2.26
–2.68
–3.10
–3.52
–3.94
–4.36
05649-043
ANALOG INPUT LEVEL
–1.84
–4.78
–5.20
0.100 0.530 0.960 1.390 1.820 2.250 2.680 3.110 3.540 3.970 4.400
ANALOG INPUT FREQUENCY
Figure 18. Low Frequency Gain Flatness
Rev. A | Page 17 of 28
AD12401
THEORY OF OPERATION
The AD12401 uses two high speed, 12-bit ADCs in a timeinterleaved configuration to double the sample rate, while
maintaining a high level of dynamic range performance. The
digital output of each ADC channel is calibrated using a
proprietary digital postprocessing technique, Advanced Filter
Bank (AFB). AFB is implemented using a state-of-the-art field
programmable gate array (FPGA) and provides a wide
bandwidth and wide temperature match for any gain, phase,
and clock timing errors between each ADC channel.
When two ADCs are time-interleaved, gain and/or phase
mismatches between each channel produce an image spur at
fS/2 − fAIN and an offset spur, as shown in Figure 19. These
mismatches can be the result of any combination of device
tolerance, temperature, and frequency deviations.
1
IMAGE SPUR
–40
X
dB
OFFSET SPUR
–60
Image Spur (dBc)
–40
–54
–62
–70
N
–70
2
3
CLOCK INPUT
–80
–90
6
4
5
05649-018
–100
–110
–120
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
200
Figure 19. Image Spur due to Mismatches Between Two Interleaved ADCs
(No AFB Digital Postprocessing)
Figure 20 shows the performance of a similar converter with
on-board AFB postprocessing implemented. The –44 dBFS
image spur has been reduced to –77 dBFS and, as a result, the
dynamic range of this time-interleaved ADC is no longer
limited by the channel matching.
0
1
–10
–20
The AD12401 requires a 400 MSPS ENCODE that is divided by 2
and distributed to each ADC channel, 180° out of phase from
each other. Internal ac-coupling and bias networks provide the
framework for flexible clock input requirements that include
single-ended sine wave, single-ended PECL, and differential
PECL. While the AD12401 is tested and calibrated using a
single-ended sine wave, properly designed PECL circuits that
provide fast slew rates (>1 V/ns) and minimize ringing result in
comparable dynamic range performance.
Aperture jitter and harmonic content are two major factors to
consider when designing the input clock circuit for the AD12401.
The relationship between aperture jitter and SNR can be
characterized using the following equation. The equation
assumes a full-scale, single-tone input signal.
SNR =
–30
2 ⎤
⎡
2
1 ⎛ 1 + ε ⎞ ⎛ 2 2 × VNOISErms ⎞ ⎥
⎟
− 20log ⎢ (20π × f A × 0 t JRMS ) 2 +
× ⎜ N ⎟ + ⎜⎜
⎟ ⎥
⎢
1. 5 ⎝ 2 ⎠ ⎝
2N
⎠ ⎥
⎢⎣
⎦
–40
–50
–60
IMAGE SPUR
3
–70
X
OFFSET SPUR
where:
2
–80
–90
5
6
4
N
–100
05649-019
dB
Aperture Delay Error (ps)
15
2.7
1.1
0.5
The AD12401 analog input is ac-coupled using a proprietary
transformer front-end circuit that provides 1 dB of gain flatness
over the first Nyquist zone and a −3 dB bandwidth of 480 MHz.
This front-end circuit provides a VSWR of 1.5 (50 Ω) over the
first Nyquist zone, and the typical full-scale input is 3.2 V p-p.
The Mini-Circuits® HELA-10 amplifier module can be used to
drive the input at these power levels.
–20
–50
Gain Error (%)
1
0.25
0.2
0.025
ANALOG INPUT
0
–30
Table 10. Image Spur vs. Channel Mismatch
For a more detailed description of time-interleaving in ADCs and a
design example using the AD12401, see Advanced Digital PostProcessing Techniques Enhance Performance in Time-Interleaved
ADC Systems, which was published in the August, 2003 edition of
the Analog Dialogue (www.analog.com/analogDialogue).
TIME-INTERLEAVING ADCS
–10
The relationship between image spur and channel mismatches
is captured in Table 10 for specific conditions.
–110
–120
0
20
40
60
80
100 120 140
FREQUENCY (MHz)
160
180
200
fA = input frequency.
tJRMS = aperture jitter.
N = ADC resolution (bits).
ε = ADCDNL (LSB).
VNOISErms = ADC input noise (LSB rms).
Figure 20. AD12401 with AFB Digital Postprocessing
Rev. A | Page 18 of 28
AD12401
Figure 21 displays the application of this relationship to a fullscale, single-tone input signal on the AD12401, where the DNL
was assumed to be 0.4 LSB, and the input noise was assumed to
be 0.8 LSB rms. The vertical marker at 0.4 ps displays the SNR
at the jitter level present in the AD12401 evaluation system,
including the jitter associated with the AD12401 itself.
65
AIN = 10MHz
64
AIN = 65MHz
63
While this product was designed to provide good PSRR
performance, system designers need to be aware of the risks
associated with switching power supplies and consider using
linear regulators in their high speed ADC systems. Switching
power supplies typically produces both conducted and radiated
energy that result in common-/differential-mode EMI currents.
Any system that requires 12-bit performance has very little
room for errors associated with power supply EMI. For example, a system goal of 74 dB dynamic range performance on the
AD12401 requires noise currents that are less than 4.5 μA and
noise voltages of less than 225 μV in the analog input path.
SNR (dB)
62
STARTUP AND RESET
AIN = 128MHz
61
60
59
AIN = 180MHz
05649-020
58
57
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
APERTURE JITTER (ps rms)
0.8
0.9
1.0
Figure 21. SNR vs. Aperture Jitter
In addition to jitter, the harmonic content of the single-ended
sine wave clock sources must be controlled. The clock source
used in the test and calibration process has a harmonic performance that is better than 60 dBc. Additionally, when using
PECL or other square-wave clock sources, unstable behavior,
such as overshoot and ringing, can affect phase matching and
degrade the image spur performance.
DIGITAL OUTPUTS
The AD12401’s digital postprocessing circuit provides two
parallel, 12-bit, 200 MSPS data output buses. By providing two
output busses that operate at one half the conversion rate, the
AD12401 eliminates the need for large, expensive, high power
demultiplexing circuits. The output data format is twos complement, maintaining the standard set by other high speed
ADCs, such as the AD9430 and AD6645. Data-ready signals are
provided for facilitating proper timing in the data capture circuit.
POWER SUPPLIES
The AD12401 requires three different supply voltages: a 1.5 V
supply for the digital postprocessing circuit, a 3.3 V supply to
facilitate digital I/O through the system, and a 3.8 V supply for
the analog conversion and clock distribution circuits. The
AD12401 incorporates two key features that result in solid
PSRR performance. First, on-board linear regulators are used to
provide an extra level of power supply rejection for the analog
circuits. The linear regulator used to supply the ADCs provides
an additional 60 dB of rejection at 100 kHz. Second, to address
higher frequency noise (where the linear regulators’ rejection
degrades), the AD12401 incorporates high quality ceramic
decoupling capacitors.
The AD12401’s FPGA configuration is stored in the on-board
EPROM and loaded into the FPGA when power is applied to
the device. The RESET pin (active low) allows the user to reload
the FPGA in case of a low digital supply voltage condition or a
power supply glitch. Pulling the RESET pin low pulls the dataready and output bits high until the FPGA is reloaded. The
RESET pin should remain low for a minimum of 200 ns. On the
rising edge of the reset pulse, the AD12401 starts loading the
configuration into the FPGA. The reload process requires a
maximum of 87 ms to complete. Valid signals on the data-ready
pins indicate the reset process is complete. In addition, system
designers must be aware of the thermal conditions of the
AD12401 at startup. If large thermal imbalances are present, the
AD12401 can require additional time to stabilize before providing
specified image spur performance.
DR_EN
The DR_EN pin is used to synchronize the collection of data
into external buffer memories. DR_EN must be held low for a
minimum amount of time (see Table 2 through Table 4 for each
ENCODE rate) to ensure correct operation. The function shuts
off DRA and DRB until the DR_EN pin is set high again. DRA
and DRB resume on the next valid DRA after DR_EN is
released. If this feature is not required, tie this pin to 3.3 V
through a 3.74 kΩ.
OVERRANGE
The differential OROUT pins are used to determine if the
AD12401 input is overranged. OROUT timing is identical to the
Channel B data. If the OROUT pin is high, then the Channel B
data coincident with the overrange indication or the Channel A
data immediately preceding it resulted from an overrange input.
If the OROUT pin is low, the operation is normal.
Rev. A | Page 19 of 28
AD12401
The AD12401 is graded out for the gain mode and should be
ordered accordingly: the AD12401-xxxKWS is calibrated in the
low gain mode, and the AD12401-xxxJWS is calibrated in the
high gain mode. Performance is not guaranteed if either grade
is used in the wrong gain mode.
The high gain mode sets the analog input voltage to
approximately 1.6 V p-p. The low gain mode sets the analog
input voltage to approximately 3.2 V p-p. For high gain mode,
the user should pull Pin 103 (H/L_GAIN) up to 3.3 V using
a 4.02 kΩ resistor. For low gain mode, the user should ground
Pin 103.
From a channel-matching perspective, the most important
consideration is external thermal influences. It is possible for
thermal imbalances in the end application to adversely affect
the dynamic performance. Due to the temperature dependence
of the image spur, substantial deviation from the factory calibration conditions can have a detrimental effect. Unbalanced
thermal influences can cause gradients across the module, and
performance degradation can result. Examples of unbalanced
thermal influences can include large heat dissipating elements
near one side of the AD12401, or obstructed airflow that does
not flow uniformly across the module. The thermal sensitivity
of the module can be affected by a change in thermal gradient
across the module of 2°C.
THERMAL CONSIDERATIONS
110
The module is rated to operate over a case temperature of 0°C
to 60°C. To maintain the tight channel matching and reliability
of the AD12401, care must be taken to ensure that proper
thermal and mechanical considerations have been made and
addressed to ensure case temperature is kept within this range.
Each application requires evaluation of the thermal management as applicable to the system design. This section provides
information that should be used in the evaluation of the
AD12401’s thermal management for each specific use.
100
TYPICAL JUNCTION
TEMPERATURE (°C)
90
80
70
60
CASE
50
40
AMBIENT
05649-021
GAIN SELECT
30
In addition to the radiation of heat into its environment, the
AD12401 module enables the flow of heat through the
mounting studs and standoffs as they contact the motherboard.
As described in the Package Integrity/Mounting Guidelines
section, the module should be secured to the motherboard
using 2-56 nuts (washer use is optional). The torque on the nuts
should not exceed 32-inch ounces. Using a thermal grease at the
standoffs results in better thermal coupling between the board
and module. Depending on the ambient conditions, airflow can
be necessary to ensure the components in the module do not
exceed their maximum operating temperature. For reliability,
the most sensitive component has a maximum junction
temperature rating of 125°C.
NO AIRFLOW
100 LFM
AIRFLOW CONDITION
300 LFM
Figure 22. Typical Temperature vs. Airflow with No Module/Board
Interface Material (Normalized to 60°C Module Case Temperature)
110
100
TYPICAL JUNCTION
90
TEMPERATURE (°C)
80
70
60
CASE
50
40
AMBIENT
05649-022
Figure 22 and Figure 23 provide a basic guideline for two key
thermal management decisions: the use of thermal interface
material between the module bottom cover/mother board and
airflow. Figure 21 characterizes the typical thermal profile of an
AD12401 that is not using thermal interface material. Figure 22
provides the same information for a configuration that uses
gap-filling thermal interface material. In this case, Thermagon
T-flex 600 Series™, 0.040” thickness, was used. These profiles
show that the maximum die temperature is reduced by
approximately 2°C when thermal interface material is used.
Figure 22 and Figure 23 also provide a guideline for determining
the airflow requirements for given ambient conditions. For
example, a goal of 120°C die temperature in a 40°C ambient
environment without the use of thermal interface material
requires an airflow of 100 LFM.
20
30
20
NO AIRFLOW
100 LFM
300 LFM
AIRFLOW CONDITION
Figure 23. Typical Temperature vs. Airflow with T-flex Module/Board
Interface Material (Normalized to 60°C Module Case Temperature Ambient)
PACKAGE INTEGRITY/MOUNTING GUIDELINES
The AD12401 is a printed circuit board (PCB)-based module
designed to provide mechanical stability and to support the
intricate channel-to-channel matching necessary to achieve high
dynamic range performance. The module should be secured to
the motherboard using 2-56 nuts (washer use is optional). The
torque on the nuts should not exceed 32-inch ounces.
Rev. A | Page 20 of 28
AD12401
The SMA edge connectors (AIN and ENC/ENC) are surface
mounted to the board to achieve minimum height of the
module. When attaching and routing the cables, one must
ensure they are stress-relieved and do not apply stress to the
SMA connector/board. The presence of stress on the cables can
degrade electrical performance and mechanical integrity of the
module. In addition to the routing precautions, the smallest
torque necessary to achieve consistent performance should be
used to secure the system cable to the AD12401’s SMA
connectors. The torque should never exceed 5-inch pounds.
Any disturbances to the AD12401 structure, including
removing the covers or mounting screws, invalidates the
calibration and results in degraded performance. See the
Outline Dimensions section for mounting stud dimensions, see
Figure 38 for PCB interface locations. Mounting stud length
typically accommodates a PCB thickness of 0.093". Consult
sales if board thickness requirements exceed this dimension.
AD12401 EVALUATION KIT
The AD12401/KIT offers an easy way to evaluate the AD12401.
The AD12401/KIT includes the AD12401 mounted on an
adapter card, the AD12401 evaluation board, the power supply
cables, a 225 MHz buffer memory FIFO board, and the Dual
Analyzer software. The user must supply a clock source, an
analog input source, a 1.5 V power supply, a 3.3 V power supply,
a 5 V power supply, and a 3.8 V power supply. The clock source
and analog input source connect directly to the AD12401. The
power supply cables (included) and a parallel port cable (not
included) connect to the evaluation board. The AD12401
works on the same evaluation board as the AD12400 and the
AD12500: GS08054.
ENCODE
The single-ended or differential ENCODE signal connects directly
to SMA connector(s) on the AD12401. A single-ended sine wave
at 10 dBm connected to the ENCODE SMA is recommended.
A low jitter clock source (
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