Analog Devices AD9432 Service Manual

12-Bit, 80 MSPS/105 MSPS
12
AIN
ENCODE
12
AD9432
GND VREFOUT
D11–D0
VREFIN
AIN
ENCODE
V
CC
V
DD
TIMING
REF
OUTPUT
STAGING
PIPELINE
ADC
BUF
T/H
OR
a
FEATURES On-Chip Reference and Track/Hold On-Chip Input Buffer 850 mW Typical Power Dissipation at 105 MSPS 500 MHz Analog Bandwidth SNR = 67 dB @ 49 MHz AIN at 105 MSPS SFDR = 80 dB @ 49 MHz AIN at 105 MSPS
2.0 V p-p Differential Analog Input Range Single 5.0 V Supply Operation
3.3 V CMOS/TTL Outputs Twos Complement Output Format
APPLICATIONS Communications Basestations and Zero-IF Subsystems Wireless Local Loop (WLL) Local Multipoint Distribution Service (LMDS) HDTV Broadcast Cameras and Film Scanners
GENERAL INTRODUCTION
The AD9432 is a 12-bit monolithic sampling analog-to-digital converter with an on-chip track-and-hold circuit and is optimized for high-speed conversion and ease of use. The product operates at a 105 MSPS conversion rate with outstanding dynamic per­formance over its full operating range.
The ADC requires only a single 5.0 V power supply and a 105 MHz encode clock for full-performance operation. No
A/D Converter
AD9432
FUNCTIONAL BLOCK DIAGRAM
external reference or driver components are required for many applications. The digital outputs are TTL/CMOS compatible and a separate output power supply pin supports interfacing with 3.3 V logic. The encode input supports either differential or single-ended and is TTL/CMOS-compatible.
Fabricated on an advanced BiCMOS process, the AD9432 is available in a 52-lead plastic quad flatpack package (LQFP) specified over the industrial temperature range (–40°C to +85°C).
REV. E
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. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2002
(VDD = 3.3 V, VCC = 5.0 V; external reference; differential encode input, unless
AD9432–SPECIFICATIONS
otherwise noted.)
Test AD9432BST/BSQ-80 AD9432BST/BSQ-105
Parameter Temp Level Min Typ Max Min Typ Max Unit
RESOLUTION 12 12 Bits
DC ACCURACY
Differential Nonlinearity 25°C I –0.75 ± 0.25 +0.75 –0.75 ± 0.25 +0.75 LSB
Full VI –1.0 ± 0.5 +1.0 –1.0 ±0.5 +1.0 LSB
Integral Nonlinearity 25°C I –1.0 ± 0.5 +1.0 –1.0 ± 0.5 +1.0 LSB
Full VI –1.5 ± 1.0 +1.5 –1.5 ± 1.0 +1.5 LSB No Missing Codes Full VI Guaranteed Guaranteed Gain Error Gain Tempco
1
1
25°C I –5 +2 +7 –5 +2 +7 % FS
Full V 150 150 ppm/°C
ANALOG INPUT
Input Voltage Range (AIN–AIN) Full V ±1.0 ± 1.0 V Common-Mode Voltage Full V 3.0 3.0 V Input Offset Voltage Full VI –5 ± 0+5 5 ± 0+5 mV Input Resistance Full VI 2 3 4 2 3 4 k Input Capacitance 25°CV 4 4 pF Analog Bandwidth, Full Power 25°C V 500 500 MHz
ANALOG REFERENCE
Output Voltage Full VI 2.4 2.5 2.6 2.4 2.5 2.6 V Tempco Full V 50 50 ppm/°C Input Bias Current Full VI 15 50 15 50 µΑ
SWITCHING PERFORMANCE
Maximum Conversion Rate Full VI 80 105 MSPS Minimum Conversion Rate Full IV 1 1 MSPS Encode Pulsewidth High (t Encode Pulsewidth Low (t Aperture Delay (t
)25°C V 2.0 2.0 ns
A
Aperture Uncertainty (Jitter) 25°C V 0.25 0.25 ps rms Output Valid Time (t
V
Output Propagation Delay (t Output Rise Time (t Output Fall Time (t
)
R
) Full V 1.9 1.9 ns
F
)25°C IV 4.0 6.2 4.0 4.8 ns
EH
)25°C IV 4.0 6.2 4.0 4.8 ns
EL
2
)
2
PD
2
)
Full VI 3.0 5.3 3.0 5.3 ns
Full VI 5.5 8.0 5.5 8.0 ns
Full V 2.1 2.1 ns
Out-of-Range Recovery Time 25°CV 2 2 ns Transient Response Time 25°CV 2 2 ns Latency Full IV 10 10 Cycles
DIGITAL INPUTS
Encode Input Common Mode Full V 1.6 1.6 V Differential Input (ENC–ENC) Full V 750 750 mV Single-Ended
Logic “1” Voltage Full IV 2.0 2.0 V
Logic “0” Voltage Full IV 0.8 0.8 V Input Resistance Full VI 3 5 8 3 5 8 k Input Capacitance 25°C V 4.5 4.5 pF
DIGITAL OUTPUTS
Logic “1” Voltage (VDD = 3.3 V) Full VI VDD – 0.05 VDD – 0.05 V Logic “0” Voltage (V
= 3.3 V) Full VI 0.05 0.05 V
DD
Output Coding Two’s Complement Two’s Complement
POWER SUPPLY
Power Dissipation
3
Full VI 790 1000 850 1100 mW
Power Supply Rejection Ratio (PSRR) 25°C I –5 +0.5 +5 –5 +0.5 +5 mV/V
I
I
VCC
VDD
Full VI 158 200 170 220 mA Full VI 9.5 12.2 12.5 16 mA
–2–
REV. E
AD9432
Test AD9432BST/BSQ-80 AD9432BST/BSQ-105
Parameter Temp Level Min Typ Max Min Typ Max Unit
DYNAMIC PERFORMANCE
Signal-to-Noise Ratio (SNR)
(Without Harmonics) f
= 10.3 MHz 25°C I 65.5 67.5 65.5 67.5 dB
IN
= 40 MHz 25°C I 65 67.2 67.2 dB
f
IN
f
= 49 MHz 25°C I 67.0 64 67.0 dB
IN
f
= 70 MHz 25°C V 66.1 66.1 dB
IN
Signal-to-Noise Ratio (SINAD)
(With Harmonics)
= 10.3 MHz 25°C I 65 67.2 65 67.2 dB
f
IN
= 40 MHz 25°C I 64.5 66.9 66.9 dB
f
IN
f
= 49 MHz 25°C I 66.7 63 66.7 dB
IN
f
= 70 MHz 25°C V 65.8 65.8 dB
IN
Effective Number of Bits
= 10 MHz 25°C V 11.0 11.0 Bits
f
IN
f
= 40 MHz 25°C V 10.9 10.9 Bits
IN
= 49 MHz 25°C V 10.9 10.9 Bits
f
IN
f
= 70 MHz 25°C V 10.7 10.7 Bits
IN
Second and Third Harmonic Distortion
= 10 MHz 25°C I –75 –85 –75 –85 dBc
f
IN
f
= 40 MHz 25°C I –73 –85 –83 dBc
IN
f
= 49 MHz 25°C I –83 –72 –80 dBc
IN
= 70 MHz 25°C V –80 –78 dBc
f
IN
Worst Harmonic or Spur
(Excluding Second and Third)
= 10 MHz 25°C I –80 –90 –80 –90 dBc
f
IN
f
= 40 MHz 25°C I –80 –90 –90 dBc
IN
f
= 49 MHz 25°C I –90 –80 –90 dBc
IN
= 70 MHz 25°C V –90 –90 dBc
f
IN
Two-Tone Intermod Distortion (IMD)
f
= 29.3 MHz; f
IN1
f
= 70.3 MHz; f
IN1
NOTES
1
Gain error and gain temperature coefficients are based on the ADC only (with a fixed 2.5 V external reference and a 2 V p-p differential analog input).
2
tV and tPD are measured from the transition points of the ENCODE input to the 50%/50% levels of the digital outputs swing. The digital output load during test is not to exceed an ac load of 10 pF or a dc current of ± 40 µA. Rise and fall times measured from 10% to 90%.
3
Power dissipation measured with encode at rated speed and a dc analog input. (Outputs Static, I
4
SNR/harmonics based on an analog input voltage of –0.5 dBFS referenced to a 2 V full-scale input range.
Specifications subject to change without notice.
IN2
IN2
4
= 30.3 MHz 25°C V –75 –75 dBc = 71.3 MHz 25°C V –66 –66 dBc
= 0.)
VDD
REV. E –3–
AD9432
WARNING!
ESD SENSITIVE DEVICE
ABSOLUTE MAXIMUM RATINGS*
VDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
CC
Analog Inputs . . . . . . . . . . . . . . . . . . . –0.5 V to V
Digital Inputs . . . . . . . . . . . . . . . . . . . –0.5 V to V
VREFIN . . . . . . . . . . . . . . . . . . . . . . . –0.5 V to V
+ 0.5 V
CC
+ 0.5 V
DD
+ 0.5 V
CC
Digital Output Current . . . . . . . . . . . . . . . . . . . . . . . . 20 mA
Operating Temperature . . . . . . . . . . . . . . . . –55°C to +125°C
Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +150°C
Maximum Junction Temperature . . . . . . . . . . . . . . . . 150°C
Maximum Case Temperature . . . . . . . . . . . . . . . . . . . 150°C
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions outside of those indicated in the operation sections of this specification is not implied. Exposure to absolute maximum ratings for extended periods may affect device reliability.
EXPLANATION OF TEST LEVELS Test Level
I 100% production tested.
II 100% production tested at 25°C and sample tested at
specified temperatures.
III Sample tested only.
IV Parameter is guaranteed by design and characterization
testing.
V Parameter is a typical value only.
VI 100% production tested at 25°C; guaranteed by design and
characterization testing for industrial temperature range.
THERMAL CHARACTERISTICS
52-Lead Plastic LQFP (ST-52)
= 50°C/W, No Airflow
JA
52-lead PowerQuad
= 25°C/W, Soldered Exposed Heat Sink, No Airflow
JA
= 33°C/W, Unsoldered Exposed Heat Sink, No Airflow
JA
= 2°C/W, Bottom of package (Exposed Heat Sink)
JC
®
4 LQFP (SQ-52)
Simulated Typical performance for 4-layer JEDEC board, horizontal orientation.
ORDERING GUIDE
Temperature Package Package
Model Ranges Descriptions Option
AD9432BSQ –40°C to +85°C 52-Lead Thermally SQ-52
-80, -105 Enhanced Plastic Quad Flatpack
AD9432BST –40°C to +85° C 52-Lead Plastic Quad ST-52
-80, -105 Flatpack (LQFP)
AD9432/PCB 25°C Evaluation Board
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 the AD9432 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.
PowerQuad is a registered trademark of AMkor Technology, Inc.
–4–
REV. E
PIN CONFIGURATION
AD9432
CC
AIN
GND
V
52 51 50 49 48 43 42 41 4047 46 45 44
1
GND GND
V
CC
GND
GND
V
CC
V
CC
ENCODE
ENCODE
GND
V
CC
GND
DGND
V
DD
PIN 1 IDENTIFIER
2
3
4
5
6
7
8
9
10
11
12
13
14 15 16 17 18 19 20 21 22 23 24 25 26
OR
D10
(MSB) D11
VCCAIN
GND
AD9432
TOP VIEW
(Not to Scale)
D9D8D7
VREFOUT
D6
CC
VREFIN
V
DDVDD
V
DGND
GND
CC
DNC
V
D5
DGND
GND
D4
39
38
37
36
35
34
33
32
31
30
29
28
27
GND V
CC
V
CC
GND
GND
GND V
DD
DGND
D0 (LSB)
D1
D2
D3
PIN FUNCTION DESCRIPTIONS
Pin Number (AD9432BST) Mnemonic Function
1, 3, 4, 9, 11, 33, 34, 35, 38, 39, 40, 43, 48, 51 GND Analog Ground 2, 5, 6, 10, 36, 37, 42, 44, 47, 52 V
CC
Analog Supply (5 V)
7 ENCODE Encode Clock for ADC–Complementary 8 ENCODE Encode Clock for ADC–True (ADC samples on rising edge of ENCODE) 14 OR Out of Range Output 15–20, 25–30 D11–D6, D5–D0 Digital Output 12, 21, 24, 31 DGND Digital Output Ground 13, 22, 23, 32 V
DD
Digital Output Power Supply (2.7 V to 3.6 V) 41 DNC Do Not Connect
45 VREFIN Reference Input for ADC (2.5 V Typical); Bypass with 0.1 µF to Ground. 46 VREFOUT Internal Reference Output (2.5 V Typical) 49 AIN Analog Input–True 50 AIN Analog Input–Complementary
DEFINITION OF SPECIFICATIONS
Analog Bandwidth (Small Signal)
The analog input frequency at which the spectral power of the fundamental frequency (as determined by the FFT analysis) is reduced by 3 dB.
Aperture Delay
The delay between a differential crossing of ENCODE and ENCODE and the instant at which the analog input is sampled.
Aperture Uncertainty (Jitter)
The sample-to-sample variation in aperture delay.
Differential Nonlinearity
The deviation of any code from an ideal 1 LSB step.
Encode Pulsewidth/Duty Cycle
Pulsewidth high is the minimum amount of time that the ENCODE pulse should be left in Logic “1” state to achieve rated performance; pulsewidth low is the minimum time ENCODE pulse should be left in low state. At a given clock rate, these specs define an acceptable Encode duty cycle.
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.
REV. E
–5–
Minimum Conversion Rate
The encode rate at which the SNR of the lowest analog signal frequency drops by no more than 3 dB below the guaranteed limit.
Maximum Conversion Rate
The encode rate at which parametric testing is performed.
Output Propagation Delay
The delay between a differential crossing of ENCODE and ENCODE and the time when all output data bits are within valid logic levels.
Power Supply Rejection Ratio
The ratio of a change in input offset voltage to a change in power supply voltage.
Signal-to-Noise Plus Distortion (SINAD)
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, including harmonics but excluding dc.
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.
AD9432
V
DD
DIGITAL OUTPUT
DIGITAL OUTPUT
Spurious-Free Dynamic Range (SFDR)
The ratio of the rms signal amplitude to the rms value of the peak spurious spectral component. The peak spurious compo­nent may or may not be a harmonic. May be reported in dBc (i.e., degrades as signal level is lowered), or in dBFS (always related back to converter full scale).
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.
SAMPLE N–1
AIN
ENCODE
ENCODE
D11–D0
SAMPLE N
t
A
t
EH
DATA N–11 DATA N–10 N–9 DATA N–1 DATA N DATA N + 1
SAMPLE N+1
t
EL
N–2
Figure 1. Timing Diagram
V
CC
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. May be reported in dBc (i.e., degrades as signal level is lowered), or in dBFS (always related back to converter full scale).
Worst Harmonic
The ratio of the rms signal amplitude to the rms value of the worst harmonic component, reported in dBc.
SAMPLE N+10 SAMPLE N+11
SAMPLE N+9
1/f
S
t
PD
t
V
V
CC
VREFIN
Figure 2. Equivalent Voltage Reference Input Circuit
V
CC
Q1
NPN
VREFOUT
OUTPUT
V
REF
Figure 3. Equivalent Voltage Reference Output Circuit
V
CC
AIN
AIN
5k
7k
17k
ENCODE ENCODE
100
8k
17k
100
8k
Figure 4. Equivalent Encode Input Circuit
Figure 5. Equivalent Digital Output Circuit
5k
7k
ANALOG INPUT
Figure 6. Equivalent Analog Input Circuit
–6–
REV. E
AIN INPUT FREQUENCY – MHz (–0.5dBFS)
70
0
SNR – dB
50 100 150 200
250
65
60
55
50
ANALOG INPUT FREQUENCY – MHz
0 100
dBc
20 12040 14060 16080
50
40
60
70
80
90
100
180
2nd or 3rd (–3.0dBFS)
2nd or 3rd (–6.0dBFS)
2nd or 3rd (–0.5dBFS)
200
ENCODE = 105MSPS
Typical Performance Characteristics–
AD9432
90
85
80
75
dB
70
AIN = 10.3MHz
SFDR
SNR
65
SINAD
60
020
40 60 80 100 120 140 160
ENCODE – MSPS
TPC 1. SNR/SINAD/SFDR vs. fS: fIN = 10.3 MHz
50
55
60
65
70
75
dBc
80
85
90
95
100
020
3rd
2nd
40 60 80 100 120 140 160
ENCODE – MSPS
AIN = 10.3MHz
TPC 2. Harmonics vs. fS: fIN = 10.3 MHz
TPC 4. SNR vs. AIN Input Frequency, Encode = 105 MSPS
TPC 5. Harmonics vs. fIN: fS = 105 MSPS
REV. E
70
65
60
SINAD (–3.0dBFS)
55
dB
50
45
40
020
SINAD (–6.0dBFS)
SINAD (–0.5dBFS)
40 60 80 100 120 140 160
ANALOG INPUT FREQUENCY – MHz
TPC 3. SINAD vs. fIN: fS = 105 MSPS
ENCODE = 105MSPS
180
200
–7–
100
ENCODE = 105MSPS
90
80
WORST OTHER (–6.0dBFS)
70
dBc
60
WORST OTHER (–0.5dBFS)
WORST OTHER (–3.0dBFS)
50
40
020
40 60 80 100 120 140 160
ANALOG INPUT FREQUENCY – MHz
180 200
TPC 6. Worst-Case Spur (Other than Second and Third) vs. f
: fS = 105 MSPS
IN
AD9432
0
10
20
30
40
50
60
dB
70
80
90
100
110
120
ENCODE = 105MSPS AIN = 10.3MHz (–0.53dBFS) SNR = 67.32dB SINAD = 67.07dB SFDR = –85dBc
SAMPLES
TPC 7. Spectrum: fS = 105 MSPS, fIN = 10.3 MHz
0
ENCODE = 105MSPS
–10
AIN = 27.0MHz (–0.52dBFS) SNR = 67.3dB
–20
SINAD = 67.0dB SFDR = –83.1dBc
30
40
50
60
dB
70
80
90
100
110
120
SAMPLES
TPC 8. Spectrum: fS = 105 MSPS, fIN = 27 MHz
0
ENCODE = 105MSPS
–10
AIN = 50.3MHz (–0.46dBFS) SNR = 67.0dB
–20
SINAD = 66.7dB
–30
SFDR = –80dBc
40
50
60
dB
70
80
90
100
110
120
SAMPLES
TPC 10. Spectrum: fS = 105 MSPS, fIN = 50.3 MHz
0
AIN1 = 29.3MHz (–7dBFS)
–10
AIN2 = 30.3MHz (–7dBFS) ENCODE = 105MSPS
20
30
40
50
60
dBc
70
80
90
100
110
120
SAMPLES
TPC 11. Two-Tone Spectrum, Wideband: fS = 105 MSPS, AIN1 = 29.3 MHz, AIN2 = 30.3 MHz
0
ENCODE = 105MSPS
–10
AIN = 40.9MHz (–0.56dBFS) SNR = 67.2dB
–20
SINAD = 66.9dB SFDR = –80dBc
30
40
50
60
dB
70
80
90
100
110
120
SAMPLES
TPC 9. Spectrum: fS = 105 MSPS, fIN = 40.9 MHz
–8–
0
AIN1 = 70.3MHz (–7dBFS)
–10
AIN2 = 71.3MHz (–7dBFS) ENCODE = 105MSPS
20
30
40
50
60
dBc
70
80
90
100
110
120
SAMPLES
TPC 12. Two-Tone Spectrum, Wideband: fS = 105 MSPS, AIN1 = 70.3 MHz, AIN2 = 71.3 MHz
REV. E
110
LSB
INL
0.50
0.75
0.25
0.00
0.25
0.50
0.75
1.00
–1.00
CURRENT – mA
02
VOLTAGE – V
4810
2.0
2.5
3.0
1.5 6
100
90
80
ENCODE = 105MSPS
70
AIN = 50.3MHz
60
50
40
30
20
10
WORST-CASE SPURIOUS – dBc AND dBFS
0
–80 –70
1.00
0.75
0.50
0.25
dBFS
dBc
60 40 30 20 10
50 0
ANALOG INPUT POWER LEVEL dBFS
TPC 13. Single Tone SFDR
AD9432
TPC 15. Integral Nonlinearity: fS = 105 MSPS
0.00
LSB
0.25
0.50
0.75
1.00
DNL
TPC 14. Differential Nonlinearity: fS = 105 MSPS
TPC 16. Voltage Reference Output vs. Current Load
REV. E
–9–
AD9432
APPLICATION NOTES Theory of Operation
The AD9432 is a multibit pipeline converter that uses a switched capacitor architecture. Optimized for high speed, this converter provides flat dynamic performance up to frequencies near Nyquist. DNL transitional errors are calibrated at final test to a typical accuracy of 0.25 LSB or less.
USING THE AD9432
Analog Input
The analog input to the AD9432 is a differential buffer. The input buffer is self-biased by an on-chip resistor divider that sets the dc common-mode voltage to a nominal 3 V (see Equivalent Circuits section). Rated performance is achieved by driving the input differentially. Minimum input offset voltage is obtained when driving from a source with a low differential source impedance such as a transformer in ac applications. Capacitive coupling at the inputs will increase the input offset voltage by as much as ±25 mV. Driving the ADC single-endedly will degrade performance. For best dynamic performance, impedances at AIN and AIN should match.
Special care was taken in the design of the analog input section of the AD9432 to prevent damage and corruption of data when the input is overdriven. The nominal input range is 2 V p-p. Each analog input will be 1 V p-p when driven differentially.
4.0
3.5
AIN
AD9432
ENCODE
ENCODE
PECL GATE
510
GND
510
0.1␮F
0.1␮F
Figure 8. AC Coupling to ENCODE Inputs
ENCODE Voltage Level Definition
The voltage level definitions for driving ENCODE and ENCODE in single-ended and differential mode are shown in Figure 9.
ENCODE Inputs Differential Signal Amplitude (V
) . . . . . . . . . . . 500 mV min
ID
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 750 mV nom
High Differential Input Voltage (V Low Differential Input Voltage (V Common-Mode Input (V
) . . . . . . . 1.25 V min, 1.6 V nom
ICM
High Single-Ended Voltage (V Low Single-Ended Voltage (V
ENCODE
ENCODE
ENCODE
0.1␮F
ILS
V
IHD
V
ICM
V
ILD
V
IHS
V
ILS
) . . . . . . . . . . 3.5 V max
IHD
) . . . . . . . . . . . . . 0 V min
ILD
) . . . . . 2 V min to 3.5 V max
IHS
) . . . . . 0 V min to 0.8 V max
V
ID
3.0
2.5
2.0
AIN
Figure 7. Full-Scale Analog Input Range
ENCODE Input
Any high speed A/D converter is extremely sensitive to the qual­ity of the sampling clock provided by the user. A track/hold circuit is essentially a mixer, and any noise, distortion, or timing jitter on the clock will be combined with the desired signal at the A/D output. For that reason, considerable care has been taken in the design of the ENCODE input of the AD9432, and the user is advised to give commensurate thought to the clock source. The ENCODE input supports either differential or single-ended and is fully TTL/CMOS compatible.
Note that the ENCODE inputs cannot be driven directly from PECL level signals (V
is 3.5 V max). PECL level signals can
IHD
easily be accommodated by ac coupling as shown in Figure 8. Good performance is obtained using an MC10EL16 in the circuit to drive the encode inputs.
Figure 9. Differential and Single-Ended Input Levels
Often, the cleanest clock source is a crystal oscillator producing a pure sine wave. In this configuration, or with any roughly symmetrical clock input, the input can be ac-coupled and biased to a reference voltage that also provides the ENCODE. This ensures that the reference voltage is centered on the encode signal.
Digital Outputs
The digital outputs are 3.3 V (2.7 V to 3.6 V) TTL/CMOS­compatible for lower power consumption. The output data format is Two’s Complement, illustrated in Table I. The out of range (OR) output (logic LOW for normal operation) will be HIGH during any clock cycle when the ADC output data (Dx) reach positive or negative full scale (–2048 or +2047). The OR is internally generated each clock cycle, has the same pipe­line latency and propagation delay as the ADC output data, and will remain HIGH until the output data reflect an in-range condition. The ADC output bits (Dx) will not roll over, and will therefore remain at positive or negative full scale (+2048 or –2047) while the OR output is HIGH.
–10–
REV. E
AD9432
AIN – MHz
0
dB
20 60
64
40
63
62
61
60
SNR
SINAD
65
66
Table I. Output Coding (VREF = 2.5 V) (Two’s Complement)
Code AIN–AIN (V) Digital Output
+2047 1.000 0111 1111 1111
The dc common-mode voltage for the AD8138 outputs can be adjusted via input V
to provide the 3 V common-mode voltage
OCM
the AD9432 inputs require.
500
••
••
10pF
AD9432
0 0 0000 0000 0000
–1 –0.00049 1111 1111 1111
••
••
–2048 –1.000 1000 0000 0000
Voltage Reference
A stable and accurate 2.5 V voltage reference is built into the
VIN
50
500
AD8138
V
OCM
500
50
22pF
50
AIN
AIN
5V
2k
AD9432 (VREFOUT). In normal operation the internal refer­ence is used by strapping Pin 45 to Pin 46 and placing a 0.1 µF decoupling capacitor at VREFIN.
25
500
10pF
3k
0.1F
The input range can be adjusted by varying the reference voltage applied to the AD9432. No appreciable degradation in perfor­mance occurs when the reference is adjusted ±5%. The full-scale
Figure 10. AD8138/AD9432 Schematic
range of the ADC tracks reference voltage changes linearly.
Timing
The AD9432 provides latched data outputs, with 10 pipeline delays. Data outputs are included or available one propagation delay (t
) after the rising edge of the encode command
PD
(see Figure 1). The length of the output data lines and loads placed on them should be minimized to reduce transients within the AD9432; these transients can detract from the converter’s dynamic performance.
The minimum guaranteed conversion rate of the AD9432 is 1 MSPS. At internal clock rates below 1 MSPS, dynamic performance may degrade. Therefore, input clock rates below 1 MHz should be avoided.
During initial power-up, or whenever the clock to the AD9432 is interrupted, the output data will not be accurate data for 200 ns or 10 clock cycles, whichever is longer.
Figure 11. Measured SNR and SINAD (Encode = 105 MSPS)
Using the AD8138 to Drive the AD9432
A new differential output op amp from Analog Devices, Inc.,
70
the AD8138, can be used to drive the AD9432 in dc-coupled applications. The AD8138 was specifically designed for ADC driver applications. Superior SNR performance is maintained up to analog frequencies of 30 MHz. The AD8138 op amp provides
–80
H2
single-ended-to-differential conversion, providing for a low-cost option to transformer coupling for ac applications as well.
dB
H3
The circuit in Figure 10 was breadboarded and the measured performance is shown in Figures 11 and 12. The figures shown
90
are for ± 5 V supplies at the AD8138—performance dropped by about 1 dB–2 dB with a single 5 V supply at the AD8138.
Figure 11 shows SNR and SINAD for a –1 dBFS analog input frequency varied from 2 MHz to 40 MHz with an encode rate of 105 MSPS. The measurements are for nominal conditions at room temperature. Figure 12 shows the second and third har­monic distortion performance under the same conditions.
–100
0204060
AIN – MHz
Figure 12. Measured Second and Third Order Harmonic Distortion (Encode = 105 MSPS)
REV. E
–11–
AD9432
[T]
86 ACQS
STOP:
TEK 5.00GS/s
T
2
CH2
CH1 1.00V 1.00V M 5.00ns CH1 1.20V
C1 MAX
2.33V
C1 MIN 810mV
C1 FREQ
106.3167MHz LOW SIGNAL AMPLITUDE
EVALUATION BOARD
The AD9432 evaluation board offers an easy way to test the AD9432. It requires an analog signal, encode clock, and power supplies as inputs. The clock is buffered on the board to provide the clocks for an on-board DAC and latches. The digital outputs and output clock are available at a standard 37-pin connector P7.
Power Connector
Power is supplied to the board via two detachable 4-pin power strips P30, P40.
P40
P1 VCC2 5 V/165 mA DAC Supply P2 GND P3 VCC 5 V/200 mA ADC Analog Supply P4 GND
P30
P5 No Connect P6 No Connect P7 VD 3.3 V /105 mA Latch, ADC Digital Output Supply P8 GND
Analog Inputs
The evaluation board accepts a 2 V p-p analog input signal at SMB connector P2. This single-ended signal is ac-coupled by capacitor C11 and drives a wideband RF transformer T1 (Mini­Circuits ADT1-1WT) that converts the single-ended signal to a differential signal. (The AD9432 should be driven differentially to provide optimum performance.) The evaluation board is shipped with termination resistors R4, R5, which provide the effective 50 termination impedance; input termination resistor R10 is optional. Note: The second harmonic distortion that some RF transformers tend to introduce at high frequencies can be reduced by coupling two transformers in series as shown in Figure 13. (Improvements on the order of 3 dB–4 dB can be realized.)
C1
0.1␮F
TO AIN+
TO AIN–
C2
0.1␮F
IN
T2T1
R1 25
R2 25
Figure 13. Improving Second Harmonic Distortion Performance
TEK 5.00GS/s
STOP:
2
CH1
500mV
CH3
2.00V
14 ACQS
[T]
T
500mV M 5.00ns CH1 3.00V
CH2
C1 MAX
3.4V
C1 MIN
2.5mV
C1 FREQ
49.995MHz LOW SIGNAL AMPLITUDE
Figure 14. Analog Input Levels
The full-scale analog inputs to the ADC should be two 1 V p-p signals 180 degrees out of phase with each other, as shown in Figure 14. The analog inputs are dc biased by two on-chip resistor dividers that set the common-mode voltage to approxi­mately 0.6 × VCC (0.6 × 5 = 3 V). AIN+ and AIN– each vary between 2.5 V and 3.5 V as shown in the two upper traces in Fig­ure 14. The lower trace is the input at SMB P2 (on a 2 V/div scale).
Encode
The encode input to the board is at SMB connector P3. The (>1 V p-p) input is ac-coupled and drives two high-speed differ­ential line receivers (MC10EL16). These receivers provide subnanosecond rise times at their outputs—a requirement for the ADC clock inputs for optimum performance. The EL16 outputs are PECL levels and must be ac-coupled to meet the common-mode dc levels required at the AD9432 encode inputs. A PECL/TTL translator (MC100ELT23), provides the clocks required at the output latches, DAC, and 37-pin connector.
Note: Jitter performance on the clock source is critical at this performance level; a stable, crystal-controlled signal generator is used to generate all of the ADC performance plots. Figure 15 shows the Encode+ clock at the ADC. The 3 V latch clock generated on the card is also shown in the plot.
–12–
Figure 15. Encode+ Clock and Latch Clock
REV. E
AD9432
DATA OUTPUTS
The ADC digital outputs are latched on the board by two 574s; the latch outputs are available at the 37-pin connector at Pins 25–36. A latch output clock (data ready) is available at Pin 21, with the complement at Pin 2. There are series termination resistors on the data and clock outputs. These can be changed if required to accommodate different loading situations. Figure 16 shows a data bit switching and output clock (DR) at the connector.
CH2
265 ACQS
[T]
T
C1 MAX
3.06V
C1 MIN –390mV
C1 FREQ
105.4562MHz
TEK 5.00GS/s
STOP:
2
CH1 1.00V 1.00V M 5.00ns CH1 1.20V
Figure 16. Data Bit and Clock at 37-Pin Connector
REFERENCE
The AD9432 has an on-chip reference of 2.5 V available at VREFOUT (Pin 46). Most applications will simply tie this output to the VREFIN input (Pin 45). This is accomplished jumping E4 to E6 on the board. An external voltage reference can drive the VREFIN pin if desired by strapping E4 to E3 and placing an AD780 voltage reference on the board (not supplied).
DAC
The evaluation board has an on-board reconstruction DAC (AD9752). This is placed only to facilitate testing and debug of the board. It should not be used to measure the performance of the ADC, as it will not accurately indicate the ADC performance. The DAC output is available at SMB P1. It will drive a 50 load. Provision to power down the DAC is at Pin 15 at the DAC.
PCB LAYOUT
The PCB is designed on a four-layer (1 oz. Cu) board. Compo­nents and routing are on the top layer with a ground flood for additional isolation. Test and ground points were judiciously placed to facilitate high-speed probing. A common ground plane exists on the second layer. The third layer has three split power planes, two for the ADC and one for support logic. The DAC, components, and routing are located on the bottom layer.
TROUBLESHOOTING
If the board does not seem to be working correctly, try the following:
Verify power at IC pins.
Check that all jumpers are in the correct position for the
desired mode of operation.
Verify VREF is at 2.5 V.
Try running encode clock and analog inputs at low speeds
(10 MSPS/1 MHz) and monitor 574 outputs, DAC output, and ADC outputs for toggling.
The AD9432 Evaluation Board is provided as a design example for customers of Analog Devices, Inc. ADI makes no warranties, express, statutory, or implied, regarding merchantability or fitness for a particular purpose.
REV. E
–13–
AD9432
PCB Bill of Materials
# Quantity REFDES Device Package Value
1 30 C1–C8, C10–C13, C17, C19–C22, Capacitor 603 0.1 µF
C27–C29, C41, C42, C47, C48,
C53, C56, C58, C60, C61, C70 2 1 C9 Capacitor 603 0.01 µF 3 4 C14, C18, C31, C34 Capacitor CAPTAJD 10 µF 4 1 C15 Capacitor CAPTAJD 1 µF 5 18 E1–E13, E30, E32, E40, E42, E43 E-HOLE Test Point 6 3 P1, P2, P3 Connector SMB 7 1 P7 37-Pin Connector Female AMP 747462-2 8 2 P30, P40 Power Connector 9 6 R1, R2, R7, R8, R10, R18 Resistor 1206 50
(R1, R2, R10 Optional) 10 2 R3, R35 Resistor 1206 100 11 4 R25, R26, R31, R32 Resistor 1206 500 12 2 R6, R24 Resistor 1206 2 k 13 4 RP1–RP4 RES PAK 100 14 1 T1 Transformer Mini-Circuits
ADT1-1WT 15 1 U1 DAC SOIC AD9752 16 1 U2 Reference (Not Supplied) SOIC AD780N 17 2 U3, U4 Inverter (U4 Not Supplied) SC70 NC7SZ04P5 18 1 U9 ADC 52QFP AD9432 19 2 U12–U13 Latch SOIC 74AC574M 20 1 Z1 PECL/TTL Translator SOIC MC100ELT23 21 2 Z2, Z3 Differential Receiver SOIC MC10EL16 22 3 R4, R5, R15 Resistor 1206 24.9
–14–
REV. E
AD9432
VCC
100
RPAK_742
VD
E1
E2
U2
OR
D11
D10D9D8
9
10111213141516
9
10111213141516
8
7654321
8765432
VCC
2
5
6
37
44
47
52
13
36
VCC
22
23
32
10
9
34
AGND
U9
424140
C4
0.1␮F
AGND
EXTREF
876
NC
VOUT
2.5/3V
(NOT SUPPLIED)
+VIN
NC
TEMP
123
D7D6D5
9
RP2
100
RPAK_742
1
14151617181920252627282930
D9D8D7D6D5D4D3D2D1
OR
D10
(MSB ) D11
8765432
AD9432
VREFIN
VREFOUT
AIN
46
0.1␮F
T1
ADT1-1WT
49
50
AIN
AGND
R4
24.9R524.9
6
2
1
AIN
4
3
VCC
5
TRIM
GND
4
AGND
C15
AGND
FLOAT
C14
10␮F
+
AD780N
1F
39
AGND
AGND
E3EXTREF
E4
45
E5
C2
D4D3D2D1D0
10111213141516
9
10111213141516
8
7654321
D0
1
3
4
38
43
48
51
12
35
11
33
21
24
31
ENC
ENC
7
8
AIN
AGND
AGND
C9
0.01␮F
C70
0.1␮F
PRI SEC
1
AGND
R31
C61
AGND
AGND
0.1␮F
Z2
C7
500
RP1
AGND
AGND
0.1␮F
VCC
876
VCC
NCDDB
123
DR
0.1␮F
Y
Q0
D08
Q
AGND
Q1
D18
QB
DR
R7
50R850
AGND
NC7SZ04P5
U4 (NOT SUPPLIED)
AGND
5
GND
MC100ELT23
D1
4
R26
500
AGND
5
VEE
MC10EL16
VBB
4
C6
0.1␮F
R3
100
NC = NO CONNECT
AGND
AGND
CLOCK
R2
100R1100
VD
(R1, R2 ,
OPTIONAL)
AGND
C8
0.1␮F
AGND
R32
500
AGND
AGND
AGND
5
Q
QB
VEE
MC10EL16
VBB
4
C58
0.1␮F
R35
100
C1
C60
AGND
5
123
0.1␮F
Z1
0.1␮F
Z3
AGND
VD
C5
4
VCC
NCAGND
VCC2
876
VCC
D0
123
R25
500
VCC2
876
VCC
NCDDB
123
REV. E
VCC
AGND
C11
0.1␮F
P2
SMBPN
ANALOG
R10
50
(OPTIONAL)
AGND
C47
0.1␮F
P3
SMBPN
ENCODE
Figure 17a. PCB Schematic
–15–
AD9432
BOR
B11
B10B9B8B7B6B5B4B3B2B1B0
DR
VCC2
BYPASS
OUT
C18
C53
C56
C22
C21
C20
C19
3736353433323130292827262524232221
P37
P36
P35
P34
P33
P32
P31
P30
P29
P28
P27
P26
P7
P19
P18
P17
P16
P15
P14
P13
P12
AGND
RPAK_742
CLOCK
11
CLOCK
GND
10
GND
P11
AGND
AGND
AGND
74AC574M
191817161514131211
AGND
AGND
AGND
AGND
AGND
B0B1B2B3B4
16151413121110
16151413121110
RP3
100
1234567
1234567
10␮F
AGND
0.1␮F
0.1␮F
0.1␮F
0.1␮F
C42
0.1␮F
C41
0.1␮F
VD
AGND
VD
201918171615141312
Q0Q1Q2Q3Q4Q5Q6
VCC
U13
OUT_END0D1D2D3D4D5D6D7
123456789
AGND
D0D1D2D3D4
9
9
8
8
Q7
P25
P10P9P8P7P6P5P4P3P2
9876543
10
AGND
AGND
AGND
AGND
AGND
B5B6B7B8B9
16151413121110
16151413121110
RP4
100
1234567
1234567
VD
201918171615141312
Q0Q1Q2Q3Q4Q5Q6
VCC
U12
OUT_END0D1D2D3D4D5D6D7
123456789
D5D6D7
GND
P24
P23
AGND
D8D9D10
P22
AGND
P21
2
AGND
B10
20
DR
P20
P1
1
AGND
B11
9
9
8
8
BOR
11
Q7
10
D11ORGND
RPAK_742
CLOCK
CLOCK
74AC574M
GND
INV
MSB
VCC2
C12
P1
SMBPN
DACOUT
VCC2
C17
0.1␮F
AGND
CLOCK
28272625242322212019181716
CLK
DVDD
U1
GND
DCON
NC2
0.1␮F
C10
AVDD
AGND
ICOMP
IOUTA
IOUTB
0.1␮F
R18
R15
ACON
AGND
50
AGNDAGND
24.9
2k
R24
AGNDAGNDAGNDVCC2
C13
0.1␮F
E1 E8
2k
R6
AGND
NC3
REFIO
FSADJ
15
SLEEP
REFLO
AD9752
D11
0.1␮F
0.1␮F
C29
C27
0.1␮F
E-HOLES
0.1␮F E30
E32
E12
E11
E10
E9
D10D9D8D7D6D5D4D3D2D1D0NCNC1
123456789
B10B9B8B7B6B5B4B3B2B1B0
MSB
1011121314
C48
0.1␮F
C34
10␮F
+
VCC
AGND
(+3V)
AGND
VD
NC
8765432
P30
NC
BYPASS LATCHES
OUT
(+5V)
AGND
VCC
P40
VD
C28
C31
+
AGND
0.1␮F
10␮F
(+5V)
VCC2
1
AGND
CONNECTING
PLANE
GROUND
E42
POINTS
TEST
SCOPE
D0
E43
D11
E40
DR
AGND
CLOCK
AGND
E7DRE6
Figure 17b. PCB Schematic (Continued)
–16–
C3
U3
0.1␮F
5
123
VCC2
4
Y
VCC
NCAGND
INV
AGND
NC7SZ04P5
NC = NO CONNECT
REV. E
AD9432
Figure 18. Top Silkscreen
Figure 19. Top Level Routing
Figure 21. Split Power Plane
Figure 22. Bottom Layer Route
REV. E
Figure 20. Ground Plane
Figure 23. Bottom Silkscreen
–17–
AD9432
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
52-Lead Plastic Quad Flatpack (LQFP)
(ST-52)
0.063 (1.60)
0.030 (0.75)
0.018 (0.45)
SEATING
PLANE
MAX
39
40
0.472 (12.00) SQ
TOP VIEW
(PINS DOWN)
27
26
0.394 (10.0)
SQ
52
0.006 (0.15)
0.002 (0.05)
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
0.057 (1.45)
0.053 (1.35)
1
0.026 (0.65) BSC
0.015 (0.38)
0.009 (0.22)
14
13
THERMALLY ENHANCED
52-Lead Power Thin Plastic Quad Flatpack (LQFP_ED)
(SQ-52)
0.093 (2.35)
0.472 (12.00) SQ
0.307 (7.80)
1
TOP VIEW
(PINS DOWN)
13
14
SEATING PLANE
0.015 (0.38)
0.013 (0.32)
0.009 (0.22)
0.026 (0.65)
0.063
(1.60)
MAX
0.030 (0.75)
0.024 (0.60)
0.018 (0.45)
NOTES
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
2. ALTHOUGH NOT REQUIRED IN ALL APPLICATIONS, THE AD9432 HAS AN EXPOSED METALLIC PAD ON THE PACKAGE BOTTOM WHICH IS INTENDED TO ENHANCE THE HEAT REMOVAL PATH. TO MAXIMIZE THE REMOVAL OF HEAT, A LAND PATTERN WITH CLOSELY SPACED THERMAL VIAS TO THE GROUND PLANE(S) SHOULD BE INCORPORATED ON THE PCB WITHIN THE FOOTPRINT OF THE PACKAGE CORRESPONDING TO THE EXPOSED METAL PAD DIMENSIONS OF THE PACKAGE. THE SOLDERABLE LAND AREA SHOULD BE SOLDER MASK DEFINED AND BE AT LEAST THE SAME SIZE AND SHAPE AS THE EXPOSED PAD AREA ON THE PACKAGE. AT LEAST 0.25 MM CLEARANCE BETWEEN THE OUTER EDGES OF THE LAND PATTERN AND THE INNER EDGES OF THE PAD PATTERN SHOULD BE MAINTAINED TO AVOID ANY SHORTS.
4052
39
27
26
VIEW A
0.104 (2.65)
0.098 (2.50)
0.093 (2.35)
0.402 (10.20)
0.394 (10.00) SQ
0.386 (9.80)
(4 PLCS)
39
27
0.057 (1.45)
0.055 (1.40)
0.053 (1.35)
0.087 (2.20)
0.081 (2.05)
40 52
HEATSINK
(CENTERED)
26
0.236 (6.00)
0.232 (5.90)
0.228 (5.80)
BOTTOM VIEW
VIEW A
(4 PLCS)
EXPOSED
(PINS UP)
0.004 (0.10)
COPLANARITY
1
13
14
0.006 (0.15)
0.002 (0.05)
0.236 (6.00)
0.232 (5.90)
0.228 (5.80)
–18–
REV. E
AD9432
Revision History
Location Page
Data Sheet changed from REV. D to REV. E.
Edits to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Edits to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Edits to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Addition of text to USING THE AD9432 section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Edits to Figure 17a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Edits to Figure 17b . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Addition of SQ-52 Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
REV. E
–19–
C00587–0–1/02(E)
–20–
PRINTED IN U.S.A.
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