AD9203ARUZRL7 [ADI]

10-Bit, 40 MSPS, 3 V, 74 mW A/D Converter; 10位, 40 MSPS , 3 V , 74毫瓦的A / D转换器
AD9203ARUZRL7
型号: AD9203ARUZRL7
厂家: ADI    ADI
描述:

10-Bit, 40 MSPS, 3 V, 74 mW A/D Converter
10位, 40 MSPS , 3 V , 74毫瓦的A / D转换器

转换器 光电二极管
文件: 总28页 (文件大小:1212K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
10-Bit, 40 MSPS, 3 V, 74 mW  
A/D Converter  
AD9203  
FEATURES  
FUNCTIONAL BLOCK DIAGRAM  
CLK  
AVDD  
DRVDD  
CMOS 10-Bit, 40 MSPS sampling A/D converter  
Power dissipation: 74 mW (3 V supply, 40 MSPS)  
17 mW (3 V supply, 5 MSPS)  
Operation between 2.7 V and 3.6 V supply  
Differential nonlinearity: −0.25 LSB  
Power-down (standby) mode, 0.65 mW  
ENOB: 9.55 @ fIN = 20 MHz  
CLAMP  
AD9203  
STBY  
CLAMPIN  
AINP  
AINN  
A/D  
SHA  
GAIN  
SHA  
GAIN  
3-STATE  
A/D  
D/A  
A/D  
D/A  
REFTF  
REFBF  
CORRECTION LOGIC  
OUTPUT BUFFERS  
Out-of-range indicator  
BANDGAP  
REFERENCE  
OTR  
VREF  
Adjustable on-chip voltage reference  
IF undersampling up to fIN = 130 MHz  
Input range: 1 V to 2 V p-p differential or single-ended  
Adjustable power consumption  
Internal clamp circuit  
D9 (MSB)  
10  
+
REFSENSE  
D0 (LSB)  
0.5V  
AVSS  
PWRCON  
DFS  
DRVSS  
Figure 1.  
APPLICATIONS  
CCD imaging  
Video  
Portable instrumentation  
IF and baseband communications  
Cable modems  
Medical ultrasound  
out-of-range signal (OTR) indicates an overflow condition that  
can be used with the most significant bit to determine over- or  
underrange.  
GENERAL DESCRIPTION  
The AD9203 is a monolithic low power, single supply, 10-bit,  
40 MSPS analog-to-digital converter, with an on-chip voltage  
reference. The AD9203 uses a multistage differential pipeline  
architecture and guarantees no missing codes over the full  
operating temperature range. Its input range may be adjusted  
between 1 V and 2 V p-p.  
The AD9203 can operate with a supply range from 2.7 V to 3.6  
V, an attractive option for low power operation in high-speed  
portable applications.  
The AD9203 is specified over industrial (−40°C to +85°C)  
temperature ranges and is available in a 28-lead TSSOP package.  
The AD9203 has an onboard programmable reference. An  
external reference can also be chosen to suit the dc accuracy  
and temperature drift requirements of an application.  
PRODUCT HIGHLIGHTS  
Low Power—The AD9203 consumes 74 mW on a 3 V supply  
operating at 40 MSPS. In standby mode, power is reduced to  
0.65 mW.  
High Performance—Maintains better than 9.55 ENOB at 40  
MSPS input signal from dc to Nyquist.  
Ver y Small Package—The AD9203 is available in a 28-lead  
TSSOP.  
Programmable Power—The AD9203 power can be further  
reduced by using an external resistor at lower sample rates.  
Built-In Clamp Function—Allows dc restoration of video  
signals.  
An external resistor can be used to reduce power consumption  
when operating at lower sampling rates. This yields power  
savings for users who do not require the maximum sample rate.  
This feature is especially useful at sample rates far below 40  
MSPS. Excellent performance is still achieved at reduced power.  
For example, 9.7 ENOB performance may be realized with only  
17 mW of power, using a 5 MHz clock.  
A single clock input is used to control all internal conversion  
cycles. The digital output data is presented in straight binary or  
twos complementary output format by using the DFS pin. An  
Rev. B  
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  
Fax: 781.326.8703  
www.analog.com  
© 2004 Analog Devices, Inc. All rights reserved.  
AD9203  
TABLE OF CONTENTS  
Specifications..................................................................................... 3  
Driving the Analog Input.......................................................... 13  
Op Amp Selection Guide .......................................................... 14  
Differential Mode of Operation ............................................... 15  
Power Control............................................................................. 16  
Interfacing to 5 V Systems ........................................................ 16  
Clock Input and Considerations .............................................. 16  
Digital Inputs and Outputs ....................................................... 16  
Applications..................................................................................... 18  
Direct IF Down Conversion ..................................................... 18  
Ultrasound Applications ........................................................... 19  
Evaluation Board ............................................................................ 20  
Outline Dimensions....................................................................... 25  
Ordering Guide .......................................................................... 25  
Absolute Maximum Ratings............................................................ 5  
Thermal Characteristics .............................................................. 5  
ESD Caution.................................................................................. 5  
Pin Configuration and Function Descriptions............................. 6  
Terminology ...................................................................................... 7  
Typical Performance Characteristics ............................................. 8  
Operations ....................................................................................... 11  
Theory of Operation .................................................................. 11  
Operational Modes..................................................................... 11  
Input and Reference Overview................................................. 12  
Internal Reference Connection ................................................ 12  
External Reference Operation .................................................. 13  
Clamp Operation........................................................................ 13  
REVISION HISTORY  
8/04—Data sheet changed from Rev. A to Rev. B  
Changes to Table 5.......................................................................... 16  
4/01—Data sheet changed from Rev. 0 to Rev. A  
Updated Format..................................................................Universal  
Changes to TPC 2............................................................................. 8  
Added Figures 41 to 46 .................................................................. 23  
7/99—Revision 0: Initial Version  
Rev. B | Page 2 of 28  
AD9203  
SPECIFICATIONS  
AVDD = 3 V, DRVDD = 3 V, FS = 40 MSPS, input span from 0.5 V to 2.5 V, internal 1 V reference, PWRCON = AVDD, 50% clock duty  
cycle, TMIN to TMAX unless otherwise noted.  
Table 1.  
Parameter  
Symbol Min  
Typ  
Max  
Unit  
Bits  
Conditions  
RESOLUTION  
10  
MAX CONVERSION RATE  
FS  
40  
MSPS  
Clock  
Cycles  
PIPELINE DELAY  
5.5  
DC ACCURACY  
Differential Nonlinearity  
Integral Nonlinearity  
Offset Error  
DNL  
INL  
EZS  
0.25 0.ꢀ LSB  
0.ꢁ5 1.4 LSB  
0.ꢁ 2.8  
0.ꢀ 4.0  
% FSR  
Gain Error  
EFS  
% FSR  
2
ANALOG INPUT  
Input Voltage Range  
Input Capacitance  
AIN  
CIN  
1
V p-p  
pF  
1.4  
Aperture Delay  
TAP  
TAJ  
BW  
2.0  
1.2  
390  
0.3  
ns  
Aperture Uncertainty (Jitter)  
Input Bandwidth (–3 dB)  
Input Referred Noise  
INTERNAL REFERENCE  
Output Voltage (0.5 V Mode)  
Output Voltage (1 V Mode)  
Output Voltage Tolerance (1 V Mode)  
Load Regulation  
ps rms  
MHz  
mV  
Switched, Single-Ended  
VREF  
VREF  
0.5  
1
5
V
V
mV  
mV  
REFSENSE = VREF  
REFSENSE = GND  
30  
1.2  
0.ꢁ5  
1.0 mA Load  
POWER SUPPLY  
Operating Voltage  
AVDD  
2.ꢀ  
3.0  
3.ꢁ  
V
DRVDD 2.ꢀ  
IAVDD  
IDRVDD  
3.0  
20.1  
4.4  
9.5  
ꢀ4  
3.ꢁ  
22.0  
ꢁ.0  
14.0  
84.0  
V
Analog Supply Current  
Digital Supply Current  
mA  
mA  
mA  
mW  
fIN= 4.8 MHz, Output Bus Load = 10pF  
fIN= 20 MHz, Output Bus Load = 20 pF  
fIN= 4.8 MHz, Output Bus Load = 10pF  
fIN= 20 MHz, Output Bus Load = 20 pF  
Power Consumption  
88.8  
0.ꢁ5  
0.04  
108.0 mW  
1.2 mW  
0.25 % FS  
Power-Down  
PD  
Power Supply Rejection Ratio  
DYNAMIC PERFORMANCE (AIN = 0.5 dBFS)  
PSRR  
1
Signal-to-Noise and Distortion  
SINAD  
f = 4.8 MHz  
f = 20 MHz  
59.ꢀ  
59.3  
dB  
dB  
5ꢀ.2  
Effective Bits  
f = 4.8 MHz  
f = 20 MHz  
Signal-to-Noise Ratio  
ENOB  
SNR  
1
9.ꢁ  
9.55  
Bits  
Bits  
9.2  
1
f = 4.8 MHz  
ꢁ0.0  
59.5  
dB  
dB  
f = 20 MHz  
5ꢀ.5  
Total Harmonic Distortion  
f = 4.8MHz  
f = 20 MHz  
THD  
−ꢀꢁ.0  
−ꢀ4.0  
dB  
−ꢁ5.0 dB  
Spurious-Free Dynamic Range  
f = 4.8 MHz1  
f = 20 MHz  
SFDR  
80  
ꢀ8  
dB  
dB  
ꢁꢀ.8  
Rev. B | Page 3 of 28  
 
 
AD9203  
Parameter  
Symbol Min  
Typ  
ꢁ8  
0.2  
0.3  
Max  
Unit  
dB  
Degree  
%
Conditions  
Two-Tone Intermodulation Distortion  
Differential Phase  
Differential Gain  
IMD  
DP  
DG  
f = 44.49 MHz and 45.52 MHz  
NTSC 40 IRE Ramp  
DIGITAL INPUTS  
High Input Voltage  
Low Input Voltage  
VIH  
VIL  
2.0  
V
V
0.4  
Clock Pulse Width High  
Clock Pulse Width Low  
Clock Period2  
11.25  
11.25  
ns  
ns  
ns  
25  
DIGITAL OUTPUTS  
High-Z Leakage  
Data Valid Delay  
Data Enable Delay  
Data High-Z Delay  
IOZ  
5.0  
µA  
ns  
ns  
ns  
Output = 0 to DRVDD  
CL= 20 pF  
CL= 20 pF  
tOD  
tDEN  
tDHZ  
5
CL= 20 pF  
LOGIC OUTPUT (with DRVDD = 3 V)  
High Level Output Voltage (IOH = 50 µA)  
High Level Output Voltage (IOH = 0.5 mA)  
Low Level Output Voltage (IOL= 1.ꢁ mA)  
Low Level Output Voltage (IOL= 50 µA)  
VOH  
VOH  
VOL  
VOL  
2.95  
2.80  
V
V
V
V
0.3  
0.05  
1 Differential Input (2 V p-p).  
2 The AD9203 will convert at clock rates as low as 20 kHz.  
N+1  
N
N+2  
N–1  
N+3  
ANALOG  
INPUT  
N+6  
N+4  
N+5  
CLOCK  
DATA  
OUT  
N–7  
N–6  
N–5  
N–4  
N–3  
N–2  
N–1  
N
N+1  
T
= 3ns MIN  
7ns MAX  
OD  
(C  
= 20pF)  
LOAD  
Figure 2. Timing Diagram  
Rev. B | Page 4 of 28  
AD9203  
ABSOLUTE MAXIMUM RATINGS  
Table 2.  
With  
Respect to Min  
Parameter  
AVDD  
DRVDD  
AVSS  
AVDD  
REFCOM  
CLK  
Max  
Unit  
V
V
V
V
V
V
V
V
AVSS  
–0.3  
–0.3  
–0.3  
–3.9  
–0.3  
–0.3  
–0.3  
+3.9  
+3.9  
+0.3  
+3.9  
DRVSS  
DRVSS  
DRVDD  
AVSS  
AVSS  
DRVSS  
AINN  
+0.3  
AVDD + 0.3  
DRVDD + 0.3  
AVDD + 0.3  
Digital Outputs  
AINP  
AVSS  
–0.3  
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  
sections of this specification is not implied. Exposure to  
absolute maximum ratings for extended periods may affect  
device reliability.  
VREF  
AVSS  
AVSS  
AVSS  
AVSS  
AVSS  
AVSS  
AVSS  
AVSS  
AVSS  
–0.3  
–0.3  
–0.3  
–0.3  
–0.3  
–0.3  
–0.3  
–0.3  
–0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
AVDD + 0.3  
150  
V
V
V
V
V
V
V
V
V
°C  
REFSENSE  
REFTF, REFBF  
STBY  
CLAMP  
CLAMPIN  
PWRCON  
DFS  
3-STATE  
Junction  
Temperature  
Storage  
Temperature  
Lead  
Temperature  
(10 s)  
–ꢁ5  
+150  
300  
°C  
°C  
THERMAL CHARACTERISTICS  
28-Lead TSSOP  
JA = 97.9°C/W  
JC = 14.0°C/W  
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. B | Page 5 of 28  
 
AD9203  
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS  
DRVSS  
DRVDD  
(LSB) D0  
D1  
1
28 AVDD  
2
AVSS  
AINN  
AINP  
27  
26  
25  
3
4
5
D2  
24 REFBF  
VREF  
6
D3  
AD9203 23  
TOP VIEW  
(Not to Scale)  
D4  
7
REFTF  
22  
21  
20  
8
D5  
PWRCON  
CLAMPIN  
9
D6  
10  
D7  
19 CLAMP  
D8 11  
18 REFSENSE  
12  
13  
14  
STBY  
(MSB) D9  
OTR  
17  
16  
15  
3-STATE  
CLK  
DFS  
Figure 3. Pin Configuration  
Table 3. Pin Function Descriptions  
Pin  
Name  
DRVSS  
DRVDD  
D0  
Description  
1
2
3
Digital Ground.  
Digital Supply.  
Bit 0, Least Significant Bit.  
4
D1  
Bit 1.  
5
D2  
Bit 2.  
D3  
Bit 3.  
D4  
Bit 4.  
8
D5  
Bit 5.  
9
Dꢁ  
Bit ꢁ.  
10  
11  
12  
13  
14  
15  
1ꢁ  
1ꢀ  
18  
19  
20  
21  
22  
23  
24  
25  
2ꢁ  
2ꢀ  
28  
Dꢀ  
D8  
D9  
OTR  
DFS  
CLK  
3-STATE  
STBY  
REFSENSE  
CLAMP  
CLAMPIN  
PWRCON  
REFTF  
VREF  
REFBF  
AINP  
AINN  
AVSS  
AVDD  
Bit ꢀ.  
Bit 8.  
Bit 9, Most Significant Bit.  
Out-of-Range Indicator.  
Data Format Select HI: Twos Complement; LO: Straight Binary.  
Clock Input.  
HI: High Impedance State Output; LO: Active Digital Output Drives.  
HI: Power-Down Mode; LO: Normal Operation.  
Reference Select.  
HI: Enable Clamp; LO: Open Clamp.  
Clamp Signal Input.  
Power Control Input.  
Top Reference Decoupling.  
Reference In/Out.  
Bottom Reference Decoupling.  
Noninverting Analog Input.  
Inverting Analog Input.  
Analog Ground.  
Analog Supply.  
Rev. B | Page ꢁ of 28  
 
AD9203  
TERMINOLOGY  
Integral Nonlinearity Error (INL)  
Signal-To-Noise Ratio (SNR)  
Linearity error refers to the deviation of each individual code  
from a line drawn from negative full scale through positive full  
scale. The point used as negative full scale occurs 1/2 LSB  
before the first code transition. Positive full scale is defined as a  
level 1 1/2 LSB beyond the last code transition. The deviation is  
measured from the middle of each particular code to the true  
straight line.  
SNR is the ratio of the rms value of the measured input signal to  
the rms sum of all other spectral components below the Nyquist  
frequency, excluding harmonics and dc. The value for SNR is  
expressed in decibels.  
Spurious-Free Dynamic Range (SFDR)  
The difference in dB between the rms amplitude of the input  
signal and the peak spurious signal.  
Differential Nonlinearity Error (DNL, No Missing Codes)  
An ideal ADC exhibits code transitions that are exactly 1 LSB  
apart. DNL is the deviation from this ideal value. Guaranteed  
no missing codes to 10-bit resolution indicates that all 1024  
codes respectively, must be present over all operating ranges.  
Offset Error  
First transition should occur for an analog value 1/2 LSB above  
negative full scale. Offset error is defined as the deviation of the  
actual transition from that point.  
Gain Error  
Signal-To-Noise and Distortion (S/N+D, SINAD) Ratio  
S/N+D is the ratio of the rms value of the measured input signal  
to the rms sum of all other spectral components below the  
Nyquist frequency, including harmonics but excluding dc. The  
value for S/N+D is expressed in decibels.  
The first code transition should occur at an analog value 1/2  
LSB above negative full scale. The last transition should occur  
for an analog value 1 1/2 LSB below the positive full scale. Gain  
error is the deviation of the actual difference between first and  
last code transitions and the ideal difference between first and  
last code transitions.  
Effective Number of Bits (ENOB)  
For a sine wave, SINAD can be expressed in terms of the  
number of bits. Using the following formula,  
Power Supply Rejection  
The specification shows the maximum change in full scale from  
the value with the supply at the minimum limit to the value  
with the supply at its maximum limit.  
N = (SINAD – 1.76)/6.02  
it is possible to get a measure of performance expressed as N,  
the effective number of bits.  
Aperture Jitter  
Aperture jitter is the variation in aperture delay for successive  
samples and is manifested as noise on the input to the A/D.  
Thus, effective number of bits for a device for sine wave inputs  
at a given input frequency can be calculated directly from its  
measured SINAD.  
Aperture Delay  
Aperture delay is a measure of the sample-and-hold amplifier  
(SHA) performance and is measured from the rising edge of the  
clock input to when the input signal is held for conversion.  
Total Harmonic Distortion (THD)  
THD is the ratio of the rms sum of the first six harmonic  
components to the rms value of the measured input signal and  
is expressed as a percentage or in decibels.  
Pipeline Delay (Latency)  
The number of clock cycles between conversion initiation and  
the associated output data being made available. New output  
data is provided on every rising edge.  
Rev. B | Page ꢀ of 28  
 
AD9203  
TYPICAL PERFORMANCE CHARACTERISTICS  
AVDD = 3 V, DRVDD = 3 V, FS = 40 MSPS, 1 V Internal Reference, PWRCON = AVDD, 50% Duty Cycle, unless otherwise noted.  
61  
59  
57  
55  
53  
51  
49  
47  
85  
80  
75  
70  
65  
60  
55  
50  
45  
40  
35  
2V SINGLE-ENDED INPUT  
2V DIFFERENTIAL INPUT  
1V DIFFERENTIAL  
INPUT  
1V SINGLE-  
ENDED INPUT  
1V DIFFERENTIAL INPUT  
2V DIFFERENTIAL  
INPUT  
2V SINGLE-  
ENDED INPUT  
1V SINGLE-ENDED INPUT  
0
20  
40  
60  
80  
100  
120  
0
20  
40  
60  
80  
100  
120  
INPUT FREQUENCY (MHz)  
INPUT FREQUENCY (MHz)  
Figure 4. SNR vs. Input Frequency and Configuration  
Figure 7. SFDR vs. Input Frequency and Configuration  
–80  
–75  
–70  
–65  
–60  
–55  
–50  
–45  
–40  
–35  
–30  
60  
55  
50  
45  
40  
35  
9.6  
8.8  
8.0  
7.1  
6.3  
5.5  
2V DIFFERENTIAL  
INPUT  
1V DIFFERENTIAL  
INPUT  
2V DIFFERENTIAL  
INPUT  
1V DIFFERENTIAL INPUT  
1V SINGLE-  
ENDED INPUT  
1V SINGLE-  
ENDED INPUT  
2V SINGLE-  
ENDED INPUT  
2V SINGLE-  
ENDED INPUT  
0
20  
40  
60  
80  
100  
120  
0
20  
40  
60  
80  
100  
120  
INPUT FREQUENCY (MHz)  
INPUT FREQUENCY (MHz)  
Figure 5. SINAD vs. Input Frequency and Configuration  
Figure 8. THD vs. Input Frequency and Configuration  
–75  
–70  
–65  
–60  
–55  
–50  
–45  
–40  
–75  
–65  
–55  
–45  
–35  
–0.5dB  
–6.0dB  
–0.5dB  
–6.0dB  
–20dB  
–20dB  
0
20  
40  
60  
80  
100  
120  
0
20  
40  
60  
80  
100  
120  
INPUT FREQUENCY (MHz)  
INPUT FREQUENCY (MHz)  
Figure 6. THD vs. Input Frequency and Amplitude  
(Differential Input VREF = 0.5 V)  
Figure 9. THD vs. Input Frequency and Amplitude  
(Differential Input VREF = 1 V)  
Rev. B | Page 8 of 28  
 
AD9203  
1.2E+07  
1.0E+07  
8.0E+06  
6.0E+06  
4.0E+06  
2.0E+06  
0.0E+00  
1.0  
0.8  
10000000  
0.6  
0.4  
0.2  
0
–0.2  
–0.4  
–0.6  
–0.8  
–1.0  
4560  
N–1  
10310  
N+1  
N
0
100 200 300 400 500 600 700 800 900  
1024  
CODE  
Figure 13. Typical DNL Performance  
Figure 10. Grounded Input Histogram  
80  
85  
70  
65  
60  
55  
50  
45  
10  
0
SNR = 59.9dB  
THD = –75dB  
SFDR = 82dB  
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
–120  
–THD  
SNR  
40  
0
10  
20  
30  
40  
50  
60  
0E+0  
2.5E+6 5.0E+6 7.5E+6 10.0E+6 12.5E+6 15.0E+6 17.5E+6 20.0E+6  
SAMPLE RATE (MSPS)  
Figure 14. Single Tone Frequency Domain Performance (Input Frequency =  
10 MHz, Sample Rate = 40 MSPS 2 V Differential Input, 8192 Point FFT)  
Figure 11. SNR and THD vs. Sample Rate (fIN = 20 MHz)  
80  
1.0  
0.8  
75  
0.6  
–THD  
0.4  
70  
65  
0.2  
0
–0.2  
–0.4  
–0.6  
–0.8  
–1.0  
60  
SNR  
55  
50  
2.5  
3.0  
3.5  
4.0  
0
100 200 300 400 500 600 700 800 900  
1024  
SUPPLY VOLTAGE (V)  
Figure 12. Typical INL Performance  
Figure 15. SNR and THD vs. Power Supply  
(fIN = 20 MHz, Sample Rate = 40 MSPS)  
Rev. B | Page 9 of 28  
AD9203  
0
–1  
–2  
–3  
–4  
–5  
–6  
–7  
–8  
0.2  
0.1  
0
0.5V  
–0.1  
–0.2  
–0.3  
–0.4  
1V  
–9  
10  
100  
1000  
–40  
–20  
0
20  
40  
60  
80  
100  
INPUT FREQUENCY (MHz)  
TEMPERATURE (°C)  
Figure 16. Full Power Bandwidth  
Figure 18. Reference Voltage vs. Temperature  
3500  
3000  
2500  
2000  
1500  
1000  
500  
1V REFERENCE  
0.5V REFERENCE  
0
0
200  
400  
600  
800  
1000  
OFF-TIME (ms)  
Figure 17. Wake-Up Time vs. Off Time (VREF Decoupling = 10 µF)  
Rev. B | Page 10 of 28  
AD9203  
OPERATIONS  
THEORY OF OPERATION  
OPERATIONAL MODES  
The AD9203 implements a pipelined multistage architecture to  
achieve high sample rates while consuming low power. It  
distributes the conversion over several smaller A/D subblocks,  
refining the conversion with progressively higher accuracy as it  
passes the results from stage to stage. As a consequence of the  
distributed conversion, the AD9203 requires a small fraction of  
the 1023 comparators used in a traditional 10-bit flash-type  
A/D. A sample-and-hold function within each of the stages  
permits the first stage to operate on a new input sample while  
the remaining stages operate on preceding samples.  
The AD9203 may be connected in several input configurations,  
as shown in Table 4.  
The AD9203 may be driven differentially from a source that  
keeps the signal peaks within the power supply rails.  
Alternatively, the input may be driven into AINP or AINN from  
a single-ended source. The input span will be 2 the  
programmed reference voltage. One input will accept the signal,  
while the opposite input will be set to midscale by connecting it  
to the internal or an external reference. For example, a 2 V p-p  
signal may be applied to AINP while a 1 V reference is applied  
to AINN. The AD9203 will then accept a signal varying  
between 2 V and 0 V. See Figure 19, Figure 20, and Figure 21 for  
more details.  
Each stage of the pipeline, excluding the last, consists of a low  
resolution flash A/D connected to a switched capacitor DAC  
and interstage residue amplifier (MDAC). The residue amplifier  
magnifies the difference between the reconstructed DAC output  
and the flash input for the next stage in the pipeline. One bit of  
redundancy is used in each one of the stages to facilitate digital  
correction of flash errors. The last stage simply consists of a  
flash A/D.  
The single-ended (ac-coupled) input of the AD9203 may also be  
clamped to ground by the internal clamp switch. This is  
accomplished by connecting the CLAMP pin to AINN or AINP.  
Digital output formats may be configured in binary and twos  
complement. This is determined by the potential on the DFS  
pin. If the pin is set to Logic 0, the data will be in straight binary  
format. If the pin is asserted to Logic 1, the data will be in twos  
complement format.  
The input of the AD9203 incorporates a novel structure that  
merges the input sample-and-hold amplifier (SHA) and the first  
pipeline residue amplifier into a single, compact switched  
capacitor circuit. This structure achieves considerable noise and  
power savings over a conventional implementation that uses  
separate amplifiers by eliminating one amplifier in the pipeline.  
By matching the sampling network of the input SHA with the  
first stage flash A/D, the AD9203 can sample inputs well  
beyond the Nyquist frequency with no degradation in  
Power consumption may be reduced by placing a resistor  
between PWRCON and AVSS. This may be done to conserve  
power when not encoding high-speed analog input frequencies  
or sampling at the maximum conversion rate. See the  
performance. Sampling occurs on the falling edge of the clock.  
Power Control section for more information.  
Table 4. Modes  
Name  
Figure Number  
Advantages  
1 V Differential  
Figure 28 with VREF Connected to  
REFSENSE  
Differential Modes Yield the Best Dynamic Performance  
2 V Differential  
Figure 28 with REFSENSE Connected to  
AGND  
Differential Modes Yield the Best Dynamic Performance  
1 V Single-Ended  
2 V Single-Ended  
Figure 20  
Figure 19  
Video and Applications Requiring Clamping Require Single-Ended Inputs  
Video and Applications Requiring Clamping Require Single-Ended Inputs  
Rev. B | Page 11 of 28  
 
 
AD9203  
INPUT AND REFERENCE OVERVIEW  
Like the voltage applied to the top of the resistor ladder in a  
flash A/D converter, the value VREF defines the maximum  
input voltage to the A/D core. The minimum input voltage to  
the A/D core is automatically defined to be −VREF.  
Figure 19 illustrates the input configured with a 1 V reference.  
This will set the single-ended input of the AD9203 in the 2 V  
span (2 × VREF). This example shows the AINN input is tied to  
the 1 V VREF. This will configure the AD9203 to accept a 2 V  
input centered around 1 V.  
2V  
AINP  
0V  
The addition of a differential input structure gives the user an  
additional level of flexibility that is not possible with traditional  
flash converters. The input stage allows the user to easily  
configure the inputs for either single-ended operation or  
differential operation. The A/D’s input structure allows the dc  
offset of the input signal to be varied independently of the input  
span of the converter. Specifically, the input to the A/D core is  
the difference of the voltages applied at the AINP and AINN  
input pins. Therefore, the equation,  
AINN  
REFTF  
2V  
0.1µF  
ADC  
10µF  
CORE  
0.1µF  
REFBF  
1V  
0.1µF  
VREF  
+
0.5V  
10µF  
0.1µF  
V
CORE = AINP AINN  
(1)  
LOGIC  
defines the output of the differential input stage and provides  
the input to the A/D core.  
REFSENSE  
AD9203  
Figure 19. Internal Reference Set for a 2 V Span  
The voltage, VCORE, must satisfy the condition,  
VREF VCORE VREF  
Figure 20 illustrates the input configured with a 0.5 V reference.  
This will set the single-ended input of the ADC in a 1 V span  
(2 × VREF). The AINN input is tied to the 0.5 VREF. This will  
configure the AD9203 to accept a 1 V input centered around  
0.5 V.  
(2)  
where VREF is the voltage at the VREF pin.  
The actual span (AINP − AINN) of the ADC is VREF.  
1V  
While an infinite combination of AINP and AINN inputs exist  
that satisfy Equation 2, an additional limitation is placed on the  
inputs by the power supply voltages of the AD9203. The power  
supplies bound the valid operating range for AINP and AINN.  
The condition,  
AINP  
0V  
AINN  
REFTF  
1.75V  
0.1µF  
ADC  
CORE  
10µF  
0.1µF  
REFBF  
1.25V  
AVSS − 0.3 V < AINP < AVDD + 0.3 V  
AVSS − 0.3 V < AINN < AVDD + 0.3 V  
(3)  
0.1µF  
VREF  
+
where AVSS is nominally 0 V and AVDD is nominally 3 V,  
defines this requirement. The range of valid inputs for AINP  
and AINN is any combination that satisfies both Equations 2  
and 3.  
0.5V  
10µF  
0.1µF  
LOGIC  
AD9203  
REFSENSE  
INTERNAL REFERENCE CONNECTION  
Figure 20. Internal Reference Set for a 1 V Span  
A comparator within the AD9203 will detect the potential of  
the VREF pin. If REFSENSE is grounded, the reference  
amplifier switch will connect to the resistor divider (see Figure  
19). That will make VREF equal to 1 V. If resistors are placed  
between VREF, REFSENSE and ground, the switch will be  
connected to the REFSENSE position and the reference  
amplitude will depend on the external programming resistors  
(Figure 21). If REFSENSE is tied to VREF, the switch will also  
connect to REFSENSE and the reference voltage will be 0.5 V  
(Figure 20). REFTF and REFBF will drive the ADC conversion  
core and establish its maximum and minimum span. The range  
of the ADC will equal twice the voltage at the reference pin for  
either an internal or external reference.  
Figure 21 shows the reference programmed by external resistors  
for 0.75 V. This will set the ADC to receive a 1.5 V span  
centered about 0.75 V. The reference is programmed according  
to the algorithm:  
VREF = 0.5 V × [1 + (RA/RB)]  
Rev. B | Page 12 of 28  
 
 
 
 
AD9203  
1.5V  
0V  
CLAMP OPERATION  
AINP  
AINN  
The AD9203 contains an internal clamp. It may be used when  
operating the input in a single-ended mode. This clamp is very  
useful for clamping NTSC and PAL video signals to ground.  
The clamp cannot be used in the differential input mode.  
REFTF  
1.875V  
0.1µF  
ADC  
10µF  
CORE  
0.1µF  
REFBF  
1.125V  
REFSENSE  
AD9203  
0.1µF  
VREF  
+
VREF  
0.1µF  
0.5V  
AINN  
10µF  
ADC  
CORE  
C
IN  
R
A
AINP  
1V p-p  
LOGIC  
AD9203  
0V DC  
REFSENSE  
50TYP  
R
B
CLAMPIN  
CLAMP  
Figure 21. Programmable Reference Configuration  
SW1  
EXTERNAL REFERENCE OPERATION  
Figure 22 illustrates the use of an external reference. An  
Figure 23. Clamp Configuration (VREF = 0.5 V)  
external reference may be necessary for several reasons. Tighter  
reference tolerance will enhance the accuracy of the ADC and  
will allow lower temperature drift performance. When several  
ADCs track one another, a single reference (internal or  
external) will be necessary. The AD9203 will draw less power  
when an external reference is used.  
Figure 23 shows the internal clamp circuitry and the external  
control signals needed for clamp operation. To enable the  
clamp, apply a logic high 1 to the CLAMP pin. This will close  
SW1, the internal switch. SW1 is opened by asserting the  
CLAMP pin low 0. The capacitor holds the voltage across CIN  
constant until the next interval. The charge on the capacitor will  
leak off as a function of input bias current (see Figure 24).  
When the REFSENSE pin is tied to AVDD, the internal  
reference will be disabled, allowing the use of an external  
reference.  
250  
200  
150  
100  
50  
The AD9203 contains an internal reference buffer. It will load  
the external reference with an equivalent 10 kΩ load. The  
internal buffer will generate positive and negative full-scale  
references for the ADC core.  
In Figure 22, an external reference is used to set the midscale set  
point for single-ended use. At the same time, it sets the input  
voltage span through a resistor divider. If the ADC is being  
driven differentially through a transformer, the external  
reference can set the center tap (common-mode voltage).  
0
–50  
3.0V  
2.0V  
1.0V  
0
0.5  
1.0  
1.5  
2.0  
2.5  
3.0  
AINP  
INPUT VOLTAGE (V)  
5V  
AD9203  
Figure 24. Input Bias Current vs. Input Voltage (FS = 40 MSPS)  
EXTERNAL  
REF (2V)  
AINN  
10µF  
0.1µF  
0.1µF  
1.5kΩ  
1.5kΩ  
DRIVING THE ANALOG INPUT  
Figure 25 illustrates the equivalent analog input of the AD9203,  
(a switched capacitor input). Bringing CLK to a logic high,  
opens S3 and closes S1 and S2. The input source connected to  
AIN and must charge Capacitor CH during this time. Bringing  
CLK to a logic low opens S2, and then S1 opens followed by  
closing S3. This puts the input in the hold mode.  
A3  
VREF  
1V  
0.1µF  
REFSENSE  
AVDD  
Figure 22. External Reference Configuration  
Rev. B | Page 13 of 28  
 
 
 
 
 
 
AD9203  
C1  
R1  
AD9203  
V
AIN  
IN  
S1  
R2  
C
C
H
H
AD9203  
C2  
+
V
BIAS  
C
C
P
AVDD/2  
S2  
S3  
P
Figure 27. AC-Coupled Input  
The f–3 dB point can be approximated by the equation:  
−3dB = 1/(2π × [R2] CEQ)  
Figure 25. Input Architecture  
f
The structure of the input SHA places certain requirements on  
the input drive source. The combination of the pin capacitance,  
CP, and the hold capacitance, CH, is typically less than 5 pF. The  
input source must be able to charge or discharge this  
capacitance to 10-bit accuracy in one half of a clock cycle.  
When the SHA goes into track mode, the input source must  
charge or discharge capacitor CH from the voltage already stored  
on CH to the new voltage. In the worst case, a full-scale voltage  
step on the input source must provide the charging current  
through the RON (100 Ω) of Switch 1 and quickly (within 1/2  
CLK period) settle. This situation corresponds to driving a low  
input impedance. Adding series resistance between the output  
of the signal source and the AIN pin reduces the drive  
requirements placed on the signal source. Figure 26 shows this  
configuration. The bandwidth of the particular application  
limits the size of this resistor. To maintain the performance  
outlined in the data sheet specifications, the resistor should be  
limited to 50 Ω or less. The series input resistor can be used to  
isolate the driver from the AD9203s switched capacitor input.  
The external capacitor may be selected to limit the bandwidth  
into the AD9203. Two input RC networks should be used to  
balance differential input drive schemes (Figure 26).  
where CEQ is the parallel combination of C1 and C2. Note that  
C1 is typically a large electrolytic or tantalum capacitor that  
becomes inductive at high frequencies. Add a small ceramic or  
polystyrene capacitor (on the order of 0.01 µF) that is negligibly  
inductive at higher frequencies while maintaining a low  
impedance over a wide frequency range.  
There are additional considerations when choosing the resistor  
values for an ac-coupled input. The ac-coupling capacitors  
integrate the switching transients present at the input of the  
AD9203 and cause a net dc bias current, IB, to flow into the  
input. The magnitude of the bias current increases as the signal  
changes and as the clock frequency increases. This bias current  
will result in an offset error of (R1 + R2) IB. If it is necessary to  
compensate for this error, consider modifying VBIAS to  
account for the resultant offset. In systems that must use dc  
coupling, use an op amp to level shift ground-referenced signals  
to comply with the input requirements of the AD9203.  
OP AMP SELECTION GUIDE  
Op amp selection for the AD9203 is highly application  
dependent. In general, the performance requirements of any  
given application can be characterized by either time domain or  
frequency domain constraints. In either case, one should  
carefully select an op amp that preserves the performance of the  
A/D. This task becomes challenging when one considers the  
AD9203s high performance capabilities coupled with other  
system level requirements such as power consumption and cost.  
The input span of the AD9203 is a function of the reference  
voltage. For more information regarding the input range, see  
the Internal Reference Connection and External Reference  
Operation sections of the data sheet.  
<50  
AIN  
V
S
AD9203  
The ability to select the optimal op amp may be further  
complicated by either limited power supply availability and/or  
limited acceptable supplies for a desired op amp. Newer, high  
performance op amps typically have input and output range  
limitations in accordance with their lower supply voltages. As a  
result, some op amps will be more appropriate in systems where  
ac coupling is allowed. When dc coupling is required, the  
headroom constraints of op amps (such as rail-to-rail op amps)  
or ones where larger supplies can be used, should be  
considered.  
Figure 26. Simple AD9203 Drive Configuration  
In many cases, particularly in single-supply operation, ac  
coupling offers a convenient way of biasing the analog input  
signal to the proper signal range. Figure 27 shows a typical  
configuration for ac-coupling the analog input signal to the  
AD9203. Maintaining the specifications outlined in the data  
sheet requires careful selection of the component values. The  
most important is the f–3 dB high-pass corner frequency. It is a  
function of R2 and the parallel combination of C1 and C2.  
The following section describes some op amps currently  
available from Analog Devices. Please contact the factory or  
local sales office for updates on Analog Devices latest amplifier  
product offerings.  
Rev. B | Page 14 of 28  
 
 
 
AD9203  
2V  
1V  
AD8051: f–3 dB = 110 MHz. Low cost. Best used for driving  
single-ended ac-coupled configuration. Operates on a 3 V  
power rail.  
AINP  
AINN  
AD9203  
AD8052: Dual Version of above amp.  
VREF  
10µF  
0.1µF  
AD8138 is a higher performance version of AD8131. Its gain is  
REFSENSE  
programmable and provides 14-bit performance.  
Figure 29. Transformer Coupled Input  
DIFFERENTIAL MODE OF OPERATION  
Since not all applications have a signal preconditioned for  
differential operation, there is often a need to perform a single-  
ended-to-differential conversion. In systems that do not need a  
dc input, an RF transformer with a center tap is one method to  
generate differential inputs beyond 20 MHz for the AD9203.  
This provides all the benefits of operating the A/D in the  
differential mode without contributing additional noise or  
distortion. An RF transformer also has the benefit of providing  
electrical isolation between the signal source and the A/D.  
The center tap of the transformer provides a convenient means  
of level-shifting the input signal to a desired common-mode  
voltage. Figure 30 illustrates the performance of the AD9203  
over a wide range of common-mode levels.  
Transformers with other turns ratios may also be selected to  
optimize the performance of a given application. For example,  
selecting a transformer with a higher impedance ratio, such as  
minicircuits T16–6T with an impedance ratio of 16, effectively  
steps up the signal amplitude, thus further reducing the driving  
requirements of the signal source.  
An improvement in THD and SFDR performance can be  
realized by operating the AD9203 in differential mode. The  
performance enhancement between the differential and single-  
ended mode is greatest as the input frequency approaches and  
goes beyond the Nyquist frequency (i.e., fIN > FS/2).  
The AD9203 can be easily configured for either a 1 V p-p or 2 V  
p-p input span by setting the internal reference. Other input  
spans can be realized with two external gain setting resistors as  
shown in Figure 21 of this data sheet. Figure 34 and Figure 35  
demonstrate the SNR and SFDR performance over a wide range  
of amplitudes required by most communication applications.  
The AD8138 provides a convenient method of converting a  
single-ended signal to a differential signal. This is an ideal  
method for generating a direct coupled signal to the AD9203.  
The AD8138 will accept a signal and shift it to an externally  
provided common-mode level. The AD8138 configuration is  
shown in Figure 28.  
–80  
1.0V REF  
0.5V REF  
–70  
3V  
3V  
10µF  
10µF  
–60  
–50  
–40  
–30  
0.1µF  
0.1µF  
0.1µF  
499Ω  
10kΩ  
28  
AVDD DRVDD  
AINP  
2
6
499Ω  
49.9Ω  
8
2
5
25  
26  
20pF  
DIGITAL  
OUTPUTS  
49.9Ω  
AD9203  
AD8138  
AINN  
AVSS DRVSS  
27  
523Ω  
49.9Ω  
4
1
3
0.1µF  
20pF  
1
10kΩ  
0
0.5  
1.0  
1.5  
2.0  
2.5  
3.0  
3.5  
499Ω  
COMMON-MODE VOLTAGE (V)  
Figure 30. THD vs. Common-Mode Voltage vs. THD  
(AIN = 2 V Differential) (fIN = 5 MHz, fS = 40 MSPS)  
Figure 28. AD8138 Driving an AD9203, a 10-Bit, 40 MSPS A/D Converter  
Figure 29 shows the schematic of a suggested transformer  
circuit. The circuit uses a Minicircuits RF transformer, model  
number T4–1T, which has an impedance ratio of four (turns  
ratio of 2).  
Rev. B | Page 15 of 28  
 
 
 
 
AD9203  
–90  
CLOCK INPUT AND CONSIDERATIONS  
The AD9203 internal timing uses the two edges of the clock  
input to generate a variety of internal timing signals. Sampling  
occurs on the falling edge. The clock input to the AD9203  
operating at 40 MSPS may have a duty cycle between 45% to  
55% to meet this timing requirement since the minimum  
specified tCH and tCL is 11.25 ns. For clock rates below 40 MSPS,  
the duty cycle may deviate from this range to the extent that  
both tCH and tCL are satisfied. See Figure 31 for dynamics vs.  
duty cycle.  
–80  
–70  
–60  
–50  
–40  
THD  
SNR  
High-speed, high-resolution A/Ds are sensitive to the quality of  
the clock input. The degradation in SNR at a given full-scale  
input frequency (fIN) due only to aperture jitter (tA) can be  
calculated with the following equation:  
40.0  
42.5  
45.0  
47.5  
50.0  
52.5  
55.0  
57.5  
60.0  
DUTY CYCLE (%)  
Figure 31. THD and SNR vs. Clock Duty Cycle  
(fIN = 5 MHz Differential, Clock = 40 MSPS)  
SNR degradation = 20 log10 [1/2π fIN tA]  
In the equation, the rms aperture jitter, tA, represents the  
rootsum square of all the jitter sources, which include the clock  
input, analog input signal, and A/D aperture jitter specification.  
Undersampling applications are particularly sensitive to jitter.  
Table 5. Power Programming Resistance  
Clock MSPS  
1
Resistor Value (k)  
50  
Clock input should be treated as an analog signal in cases where  
aperture jitter may affect the dynamic range of the AD9203.  
Power supplies for clock drivers should be separated from the  
A/D output driver supplies to avoid modulating the clock signal  
with digital noise. Low jitter crystal controlled oscillators make  
the best clock sources. If the clock is generated from another  
type of source (by gating, dividing or another method), it  
should be retimed by the original clock at the last step.  
5 to 10  
15 to 20  
>20  
100  
200  
500  
POWER CONTROL  
Power consumed by the AD9203 may be reduced by placing a  
resistor between the PWRCON pin and ground. This function  
will be valuable to users who do not need the AD9203s high  
conversion rate, but do need even lower power consumption.  
The external resistor sets the programming of the analog  
current mirrors. Table 5 illustrates the relationship between  
programmed power and performance.  
The clock input is referred to the analog supply. Its logic  
threshold is AVDD/2.  
DIGITAL INPUTS AND OUTPUTS  
Each of the AD9203 digital control inputs, 3-STATE, DFS, and  
STBY are referenced to analog ground. CLK is also referenced  
to analog ground. A low power mode feature is provided such  
that for STBY = HIGH and the static power of the AD9203  
drops to 0.65 mW.  
At lower clock rates, less power is required within the analog  
sections of the AD9203. Placing an external resistor on the  
PWRCON pin will shunt control current away from some of the  
current mirrors. This enables the ADC to convert low data rates  
with extremely low power consumption.  
Asserting the DFS pin high will invert the MSB pin, changing  
the data to a twos complement format.  
The AD9203 has an OTR (out of range) function. If the input  
voltage is above or below full scale by 1 LSB, the OTR flag will  
go high. See Figure 32.  
INTERFACING TO 5 V SYSTEMS  
The AD9203 can be integrated into 5 V systems. This is  
accomplished by deriving a 3 V power supply from the existing  
5 V analog power line through an AD3307-3 linear regulator.  
Care must be maintained so that logic inputs do not exceed the  
maximum rated values listed on the Specifications page.  
Rev. B | Page 1ꢁ of 28  
 
 
 
AD9203  
OTR  
OTR  
DATA OUTPUTS  
1
0
0
11111  
11111  
11111  
11111  
11111  
11110  
0
0
1
00000  
00000  
00000  
00001  
00000  
00000  
–FS  
–FS + 1 LSB  
+FS  
+FS – 1 LSB  
Figure 32. Output Data Format  
G1 = 20dB  
AD9203  
G2 = 20dB  
BANDPASS  
FILTER  
SAW FILTER  
OUTPUT  
MINI CIRCUITS  
50  
T4-6T  
1:4  
50Ω  
50Ω  
AINP  
200Ω  
22.1Ω  
200Ω  
AINN  
93.1Ω  
AVDD/2  
Figure 33. Simplified IF Sampling Circuit  
Rev. B | Page 1ꢀ of 28  
AD9203  
APPLICATIONS  
The distortion and noise performance of an ADC at the given  
IF frequency is of particular concern when evaluating an ADC  
for a narrowband IF sampling application. Both single tone and  
dual tone SFDR vs. amplitude are very useful in assessing an  
ADCs dynamic and static nonlinearities. SNR vs. amplitude  
performance at the given IF is useful in assessing the ADCs  
noise performance and noise contribution due to aperture jitter.  
In any application, one is advised to test several units of the  
same device under the same conditions to evaluate the given  
applications sensitivity to that particular device. Figure 34 and  
Figure 35 combine the dual tone SFDR as well as single tone  
SFDR and SNR performances at IF frequencies of 70 MHz, and  
130 MHz. Note, the SFDR vs. amplitude data is referenced to  
dBFS while the single tone SNR data is referenced to dBc. The  
performance characteristics in these figures are representative  
of the AD9203 without any preceding gain stage. The AD9203  
was operated in the differential mode (via transformer) with a  
2 V span and a sample rate of 40 MSPS. The analog supply  
(AVDD) and the digital supply (DRVDD) were set to 3.0 V.  
DIRECT IF DOWN CONVERSION  
Sampling IF signals above an ADCs baseband region (i.e., dc to  
FS/2) is becoming increasingly popular in communication  
applications. This process is often referred to as direct IF down  
conversion or undersampling. There are several potential  
benefits in using the ADC to alias (or mix) down a narrow band  
or wide band IF signal. First and foremost is the elimination of a  
complete mixer stage with its associated amplifiers and filters,  
reducing cost and power dissipation. Second is the ability to  
apply various DSP techniques to perform such functions as  
filtering, channel selection, quadrature demodulation, data  
reduction, detection, etc. A detailed discussion on using this  
technique in digital receivers can be found in Analog Devices  
Application Notes AN-301 and AN-302.  
In direct IF down conversion applications, one exploits the  
inherent sampling process of an ADC in which an IF signal  
lying outside the baseband region can be aliased back into the  
baseband region in a manner similar to a mixer downconverting  
an IF signal. Similar to the mixer topology, an image rejection  
filter is required to limit other potential interfering signals from  
also aliasing back into the ADCs baseband region.  
90  
SFDR 2 TONE  
80  
70  
SFDR 1 TONE  
A trade-off exists between the complexity of this image  
rejection filter and the ADCs sample rate and dynamic range.  
60  
50  
SNR  
The AD9203 is well suited for various IF sampling applications.  
Its low distortion input SHA has a full-power bandwidth  
extending to 130 MHz, thus encompassing many popular IF  
frequencies. Only the 2 V span should be used for  
undersampling beyond 20 MHz. A DNL of 0.25 LSB  
combined with low thermal input referred noise allows the  
AD9203 in the 2 V span to provide >59 dB of SNR for a  
baseband input sine wave. Also, its low aperture jitter of 1.2 ps  
rms ensures minimum SNR degradation at higher IF  
frequencies. In fact, the AD9203 is capable of still maintaining  
58 dB of SNR at an IF of 70 MHz with a 2 V input span.  
40  
30  
20  
10  
0
0
5
10  
15  
20  
25  
30  
INPUT POWER LEVEL (dB FULL SCALE)  
Figure 34. SNR/SFDR for IF @ 70 MHz (Clock = 40 MSPS)  
80  
70  
60  
50  
40  
30  
20  
10  
0
SFDR 2 TONE  
To maximize its distortion performance, the AD9203 should be  
configured in the differential mode with a 2 V span using a  
transformer. The center-tap of the transformer is biased to the  
reference output of the AD9203. Preceding the AD9203 and  
transformer is an optional bandpass filter as well as a gain stage.  
A low Q passive bandpass filter can be inserted to reduce out of  
band distortion and noise that lies within the AD9203s 390  
MHz bandwidth. A large gain stage(s) is often required to  
compensate for the high insertion losses of a SAW filter used for  
channel selection and image rejection. The gain stage will also  
provide adequate isolation for the SAW filter from the charge  
kick back currents associated with the AD9203’s switched  
capacitor input stage.  
SFDR 1 TONE  
SNR  
0
5
10  
15  
20  
25  
30  
35  
INPUT POWER LEVEL (dB FULL SCALE)  
Figure 35. SNR/SFDR for IF @ 130 MHz (Clock = 40 MSPS)  
Rev. B | Page 18 of 28  
 
 
 
AD9203  
AD9203 is powered from a 3 V supply rail while the high  
ULTRASOUND APPLICATIONS  
performance AD604 is powered from 5 V supply rails. An  
AD8138 is used to drive the AD9203. This is implemented due  
to the ability of differential drive techniques to cancel common-  
mode noise and input anomalies.  
The AD9203 provides excellent performance in 10-bit  
ultrasound applications. This is demonstrated by its high SNR  
with analog input frequencies up to and including Nyquist. The  
presence of spurs near the base of a fundamental frequency bin  
is demonstrated by Figure 37. Note that the spurs near the noise  
floor are more than 80 dB below fIN. This is especially valuable  
in Doppler ultrasound applications where low frequency shifts  
from the fundamental are important.  
The 74 mW power consumption gives the 40 MSPS AD9203 an  
order of magnitude improvement over older generation  
components.  
10  
FUND  
CONDITIONED  
TRANSDUCER  
SIGNAL  
SNR = 59.9dB  
THD = –75dB  
SFDR = 82dB  
0
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
SINGLE-  
3V  
ANALOG  
INPUT  
ENDED  
AD9203  
ANALOG  
AINP  
AD604  
AD8138  
TGC  
AMPLIFIER  
AINN  
GAIN  
CONTROL  
1.5V  
3V  
Figure 36. Ultrasound Connection for the AD9203  
4.5E+6  
4.7E+6  
4.9E+6  
5.1E+6  
5.3E+6  
5.5E+6  
fIN  
Figure 36 illustrates the AD604 variable gain amplifier  
configured for time gain compensation (TGC). The low power  
Figure 37. SFDR Performance Near the Fundamental Signal (8192 Point FFT,  
fIN = 5 MHz, FS = 40 MSPS)  
Rev. B | Page 19 of 28  
 
 
 
AD9203  
EVALUATION BOARD  
for single-ended and differential operation as well as 1 V and  
2 V spans. Refer to Figure 39.  
The AD9203 evaluation board is shipped wired for 2 V  
differential operation. The board should be connected to power  
and test equipment as shown in Figure 38. It is easily configured  
3V  
3V  
3V  
3V  
+
+
+
+
DRVDD  
GND  
+3-5D  
AVDD  
GND  
AVEE  
J1  
ANALOG  
INPUT  
ANTI-  
ALIASING  
FILTER  
SYNTHESIZER  
1MHz 1.9V p-p  
HP8644  
OUTPUT  
WORD  
DSP  
EQUIPMENT  
AD9203  
EVALUATION BOARD  
J5  
SYNTHESIZER  
40MHz 1V p-p  
HP8644  
EXTERNAL  
CLOCK  
Figure 38. Evaluation Board Connection  
Rev. B | Page 20 of 28  
 
 
AD9203  
Figure 39. Evaluation Board (Rev. C)  
Rev. B | Page 21 of 28  
AD9203  
Figure 40. Evaluation Board (Rev. C)  
Rev. B | Page 22 of 28  
AD9203  
Figure 41. Evaluation Board Component Side Assembly (Not to Scale)  
Figure 42. Evaluation Board Component Side (Not to Scale)  
Figure 43. Evaluation Board Solder Side Assembly (Not to Scale)  
Rev. B | Page 23 of 28  
AD9203  
Figure 44. Evaluation Board Solder Side (Not to Scale)  
Figure 45. Evaluation Board Ground Plane (Not to Scale)  
Figure 46. Evaluation Board Power Plane (Not to Scale)  
Rev. B | Page 24 of 28  
AD9203  
OUTLINE DIMENSIONS  
9.80  
9.70  
9.60  
28  
15  
4.50  
4.40  
4.30  
6.40 BSC  
1
14  
PIN 1  
0.65  
BSC  
1.20 MAX  
0.15  
0.05  
8°  
0°  
0.75  
0.60  
0.45  
0.30  
0.19  
0.20  
0.09  
SEATING  
PLANE  
COPLANARITY  
0.10  
COMPLIANT TO JEDEC STANDARDS MO-153AE  
Figure 47. 28-Lead Thin Shrink Small Outline Package  
(RU-28)  
Dimensions shown in inches and (millimeters)  
ORDERING GUIDE  
Model  
Temperature Range  
Package Description  
Package Option  
RU-28  
RU-28  
RU-28  
RU-28  
AD9203ARU  
AD9203ARURLꢀ  
AD9203ARUZ1  
AD9203ARUZRLꢀ1  
AD9203-EB  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
−40°C to +85°C  
28-Lead Thin Shrink Small Outline  
28-Lead Thin Shrink Small Outline  
28-Lead Thin Shrink Small Outline  
28-Lead Thin Shrink Small Outline  
Evaluation Board  
1 Z = Pb-free part.  
Rev. B | Page 25 of 28  
 
 
 
AD9203  
NOTES  
Rev. B | Page 2ꢁ of 28  
AD9203  
NOTES  
Rev. B | Page 2ꢀ of 28  
AD9203  
NOTES  
©
2004 Analog Devices, Inc. All rights reserved. Trademarks and  
registered trademarks are the property of their respective owners.  
C00573–0–8/04(B)  
Rev. B | Page 28 of 28  

相关型号:

AD9203ARUZRL71

10-Bit, 40 MSPS, 3 V, 74 mW A/D Converter
ADI

AD9203W

10-Bit, 40 MSPS, 3 V, 74 mW Analog-to-Digital Converter
ADI

AD9203WARUZ

10-Bit, 40 MSPS, 3 V, 74 mW Analog-to-Digital Converter
ADI

AD9203WARUZRL7

10-Bit, 40 MSPS, 3 V, 74 mW Analog-to-Digital Converter
ADI

AD9204

10-Bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS, 1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-20EBZ

1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-20EBZ1

10-Bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS, 1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-40EBZ

1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-40EBZ1

10-Bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS, 1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-65EBZ

1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-65EBZ1

10-Bit, 20 MSPS/40 MSPS/65 MSPS/80 MSPS, 1.8 V Dual Analog-to-Digital Converter
ADI

AD9204-80EBZ

1.8 V Dual Analog-to-Digital Converter
ADI