AD9236BRU-80EB [ADI]

12-Bit, 80 MSPS, 3V A/D Converter; 12位, 80 MSPS , 3V A / D转换器
AD9236BRU-80EB
型号: AD9236BRU-80EB
厂家: ADI    ADI
描述:

12-Bit, 80 MSPS, 3V A/D Converter
12位, 80 MSPS , 3V A / D转换器

转换器
文件: 总36页 (文件大小:1883K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
12-Bit, 80 MSPS, 3 V A/D Converter  
AD9236  
FUNCTIONAL BLOCK DIAGRAM  
FEATURES  
AVDD  
DRVDD  
Single 3 V supply operation (2.7 V to 3.6 V)  
SNR = 70.4 dBc to Nyquist  
AD9236  
SFDR = 87.8 dBc to Nyquist  
Low power: 366 mW  
VIN+  
VIN–  
8-STAGE  
MDAC1  
A/D  
3
SHA  
1 1/2-BIT PIPELINE  
Differential input with 500 MHz bandwidth  
On-chip reference and sample-and-hold  
DNL = 0.4 LSB  
Flexible analog input: 1 V p-p to 2 V p-p range  
Offset binary or twos complement data format  
Clock duty cycle stabilizer  
4
16  
A/D  
REFT  
REFB  
CORRECTION LOGIC  
OTR  
12  
OUTPUT BUFFERS  
D11 (MSB)  
D0 (LSB)  
VREF  
APPLICATIONS  
SENSE  
CLOCK  
0.5V  
MODE  
SELECT  
DUTY CYCLE  
STABILIZER  
High end medical imaging equipment  
IF sampling in communications receivers:  
WCDMA, CDMA-One, CDMA-2000  
Battery-powered instruments  
Hand-held scopemeters  
REF  
SELECT  
AGND  
CLK  
PDWN MODE DGND  
03066-0-001  
Figure 1. Functional Block Diagram  
Low cost digital oscilloscopes  
DTV subsystems  
presented in straight binary or twos complement formats. An  
out-of-range (OTR) signal indicates an overflow condition that  
can be used with the most significant bit to determine low or  
high overflow. Fabricated on an advanced CMOS process, the  
AD9236 is available in a 28-lead TSSOP and a 32-lead LFCSP  
and is specified over the industrial temperature range  
(–40°C to +85°C).  
GENERAL DESCRIPTION  
The AD9236 is a monolithic, single 3 V supply, 12-bit, 80 MSPS  
analog-to-digital converter featuring a high performance sam-  
ple-and-hold amplifier (SHA) and voltage reference. The  
AD9236 uses a multistage differential pipelined architecture  
with output error correction logic to provide 12-bit accuracy at  
80 MSPS and guarantee no missing codes over the full operat-  
ing temperature range.  
PRODUCT HIGHLIGHTS  
1. The AD9236 operates from a single 3 V power supply and  
features a separate digital output driver supply to accommo-  
date 2.5 V and 3.3 V logic families.  
The wide bandwidth, truly differential SHA allows a variety of  
user-selectable input ranges and common modes, including  
single-ended applications. It is suitable for multiplexed systems  
that switch full-scale voltage levels in successive channels and  
for sampling single-channel inputs at frequencies well beyond  
the Nyquist rate. Combined with power and cost savings over  
previously available analog-to-digital converters, the AD9236 is  
suitable for applications in communications, imaging, and  
medical ultrasound.  
2. Operating at 80 MSPS, the AD9236 consumes a low 366 mW.  
3. The patented SHA input maintains excellent performance for  
input frequencies up to 100 MHz, and can be configured for  
single-ended or differential operation.  
4. The AD9236 is pin compatible with the AD9215, AD9235,  
and AD9245. This allows a simplified migration from 10 bits  
to 14 bits and 20 MSPS to 80 MSPS.  
5. The DCS maintains overall ADC performance over a wide  
range of clock pulsewidths.  
A single-ended clock input is used to control all internal con-  
version cycles. A duty cycle stabilizer (DCS) compensates for  
wide variations in the clock duty cycle while maintaining excel-  
lent overall ADC performance. The digital output data is  
6. The OTR output bit indicates when the signal is beyond the  
selected input 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  
Fax: 781.326.8703  
www.analog.com  
© 2003 Analog Devices, Inc. All rights reserved.  
AD9236  
TABLE OF CONTENTS  
AD9236–DC Specifications ............................................................ 3  
Analog Input and Reference Overview ................................... 14  
Clock Input Considerations...................................................... 15  
Jitter Considerations .................................................................. 16  
Power Dissipation and Standby Mode .................................... 16  
Digital Outputs ........................................................................... 16  
Timing ......................................................................................... 17  
Voltage Reference ....................................................................... 17  
Internal Reference Connection ................................................ 17  
External Reference Operation .................................................. 18  
Operational Mode Selection..................................................... 18  
Evaluation Board........................................................................ 18  
Outline Dimensions....................................................................... 33  
Ordering Guide .......................................................................... 33  
AD9236–AC Specifications............................................................. 4  
AD9236–Digital Specifications....................................................... 5  
AD9236–Switching Specifications ................................................. 6  
Explanation of Test Levels........................................................... 6  
Absolute Maximum Ratings............................................................ 7  
Thermal Resistance ...................................................................... 7  
ESD Caution.................................................................................. 7  
Definitions of Specifications ........................................................... 8  
Pin Configurations and Functional Descriptions ........................ 9  
Equivalent Circuits......................................................................... 10  
Typical Performance Characteristics ........................................... 11  
Theory of Operation ...................................................................... 14  
REVISION HISTORY  
Revision A  
10/03—Data Sheet Changed from REV. 0 to REV. A  
Changes to Figure 30 ..................................................................... 15  
Changes to Figure 33 ..................................................................... 17  
Changes to Figure 40...................................................................... 22  
Changes to Figure 49...................................................................... 28  
Changes to Figure 50...................................................................... 29  
Changes to Table 11........................................................................ 32  
Changes to ORDERING GUIDE ................................................ 33  
Rev. A | Page 2 of 36  
AD9236  
AD9236–DC SPECIFICATIONS  
Table 1. AVDD = 3 V, DRVDD = 2.5 V, Sample Rate = 80 MSPS, 2 V p-p Differential Input, 1.0 V External Reference, unless  
otherwise noted  
AD9236BRU/AD9236BCP  
Parameter  
Temp  
Test Level  
Unit  
Min  
Typ  
Max  
RESOLUTION  
Full  
VI  
12  
Bits  
ACCURACY  
No Missing Codes  
Offset Error1  
Gain Error  
Gain Error1  
Differential Nonlinearity (DNL)2  
Integral Nonlinearity (INL)2  
TEMPERATURE DRIFT  
Offset Error1  
Gain Error  
Gain Error1  
Full  
Full  
25°C  
Full  
Full  
Full  
VI  
VI  
V
VI  
VI  
VI  
Guaranteed  
0.30  
0.10  
0.30  
0.40  
1.30  
% FSR  
% FSR  
% FSR  
LSB  
4.34  
0.65  
1.20  
0.35  
LSB  
Full  
Full  
Full  
V
V
V
6
12  
18  
ppm/°C  
ppm/°C  
ppm/°C  
INTERNAL VOLTAGE REFERENCE  
Output Voltage Error (1 V)  
Load Regulation @ 1.0 mA  
Output Voltage Error (0.5 V)  
Load Regulation @ 0.5 mA  
INPUT REFERRED NOISE  
VREF = 0.5 V  
Full  
VI  
V
V
2
0.8  
1
35  
mV  
mV  
mV  
mV  
25°C  
25°C  
25°C  
V
0.1  
25°C  
25°C  
V
V
0.55  
0.28  
LSB rms  
LSB rms  
VREF = 1.0 V  
ANALOG INPUT  
Input Span, VREF = 0.5 V  
Input Span, VREF = 1.0 V  
Input Capacitance3  
REFERENCE INPUT RESISTANCE  
POWER SUPPLIES  
Supply Voltage  
Full  
Full  
Full  
Full  
IV  
IV  
V
1
2
7
7
V p-p  
V p-p  
pF  
V
kΩ  
AVDD  
DRVDD  
Full  
Full  
IV  
IV  
2.7  
2.25  
3.0  
2.5  
3.6  
3.6  
V
V
Supply Current  
IAVDD4  
Full  
25°C  
25°C  
VI  
V
V
122  
8
0.01  
137  
mA  
mA  
% FSR  
IDRVDD4  
PSRR  
POWER CONSUMPTION  
Low Frequency Input4  
Standby Power5  
25°C  
25°C  
V
V
366  
1.0  
mW  
mW  
1 With a 1.0 V internal reference.  
2 Measured at fIN = 2.4 MHz, full-scale sine wave, with approximately 5 pF loading on each output bit.  
3 Input capacitance refers to the effective capacitance between one differential input pin and AGND. Refer to Figure 5 for the equivalent analog input structure.  
4 Measured at AC Specifications conditions without output drivers.  
5 Measured with a dc input, CLK pin inactive (i.e., set to AVDD or AGND).  
Rev. A | Page 3 of 36  
 
 
 
 
 
 
 
 
 
AD9236  
AD9236–AC SPECIFICATIONS  
Table 2. AVDD = 3 V, DRVDD = 2.5 V, Sample Rate = 80 MSPS, 2 V p-p Differential Input, 1.0 V External Reference,  
AIN = –0.5 dBFS, DCS Off, unless otherwise noted  
AD9236BRU/AD9236BCP  
Parameter  
Temp  
Test Level  
Unit  
Min  
Typ  
Max  
SIGNAL-TO-NOISE-RATIO (SNR)  
fIN = 2.4 MHz  
Full  
VI  
V
V
IV  
V
V
68.6  
dB  
dB  
dB  
dB  
dB  
dB  
25°C  
25°C  
Full  
25°C  
25°C  
70.9  
70.4  
fIN = 40 MHz  
fIN = 70 MHz  
67.8  
70.1  
69.0  
fIN = 100 MHz  
SIGNAL-TO-NOISE AND DISTORTION (SINAD)  
fIN = 2.4 MHz  
Full  
VI  
V
V
IV  
V
V
68.4  
67.4  
dB  
dB  
dB  
dB  
dB  
dB  
25°C  
25°C  
Full  
25°C  
25°C  
70.8  
70.2  
fIN = 40 MHz  
fIN = 70 MHz  
69.8  
68.0  
fIN = 100 MHz  
EFFECTIVE NUMBER OF BITS (ENOB)  
fIN = 2.4 MHz  
Full  
VI  
V
V
IV  
V
V
11.1  
10.9  
Bits  
Bits  
Bits  
Bits  
Bits  
Bits  
25°C  
25°C  
Full  
25°C  
25°C  
11.5  
11.4  
fIN = 40 MHz  
fIN = 70 MHz  
11.3  
11.0  
fIN = 100 MHz  
WORST SECOND OR THIRD  
fIN = 2.4 MHz  
Full  
VI  
V
V
VI  
V
V
–75.6  
–73.2  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
25°C  
25°C  
Full  
25°C  
25°C  
–91.3  
–87.8  
fIN = 40 MHz  
fIN = 70 MHz  
–81.4  
–76.4  
fIN = 100 MHz  
SPURIOUS FREE DYNAMIC RANGE (SFDR)  
fIN = 2.4 MHz  
Full  
VI  
V
V
IV  
V
V
75.6  
73.2  
dBc  
dBc  
dBc  
dBc  
dBc  
dBc  
25°C  
25°C  
Full  
25°C  
25°C  
91.3  
87.8  
fIN = 40 MHz  
fIN = 70 MHz  
81.4  
76.4  
fIN = 100 MHz  
Rev. A | Page 4 of 36  
 
AD9236  
AD9236–DIGITAL SPECIFICATIONS  
Table 3. AVDD = 3 V, DRVDD = 2.5 V, 1.0 V External Reference, unless otherwise noted  
AD9236BRU/AD9236BCP  
Parameter  
Temp  
Test Level  
Unit  
Min  
Typ  
Max  
LOGIC INPUTS (CLK, PDWN)  
High Level Input Voltage  
Low Level Input Voltage  
High Level Input Current  
Low Level Input Current  
Full  
Full  
Full  
Full  
Full  
IV  
IV  
IV  
IV  
V
2.0  
V
V
µA  
µA  
pF  
0.8  
+10  
+10  
–10  
–10  
Input Capacitance  
2
DIGITAL OUTPUTS (D0–D11, OTR)1  
DRVDD = 3.3 V  
High Level Output Voltage (IOH = 50 µA)  
High Level Output Voltage (IOH = 0.5 mA)  
Low Level Output Voltage (IOH = 1.6 mA)  
Low Level Output Voltage (IOH = 50 µA)  
DRVDD = 2.5 V  
Full  
Full  
Full  
Full  
IV  
IV  
IV  
IV  
3.29  
3.25  
V
V
V
V
0.2  
0.05  
High Level Output Voltage (IOH = 50 µA)  
High Level Output Voltage (IOH = 0.5 mA)  
Low Level Output Voltage (IOH = 1.6 mA)  
Low Level Output Voltage (IOH = 50 µA)  
Full  
Full  
Full  
Full  
IV  
IV  
IV  
IV  
2.49  
2.45  
V
V
V
V
0.2  
0.05  
1 Output voltage levels measured with 5 pF load on each output.  
Rev. A | Page 5 of 36  
 
 
AD9236  
AD9236–SWITCHING SPECIFICATIONS  
Table 4. AVDD = 3 V, DRVDD = 2.5 V, unless otherwise noted  
AD9236BRU/AD9236BCP  
Parameter  
Temp  
Test Level  
Unit  
Min  
Typ  
Max  
CLOCK INPUT PARAMETERS  
Maximum Conversion Rate  
Minimum Conversion Rate  
CLK Period  
Full  
Full  
Full  
Full  
Full  
VI  
V
V
V
V
80  
MSPS  
MSPS  
ns  
ns  
ns  
1
12.5  
4.0  
4.0  
CLK Pulsewidth High1  
CLK Pulsewidth Low1  
DATA OUTPUT PARAMETERS  
Output Propagation Delay (tPD)2  
Pipeline Delay (Latency)  
Aperture Delay (tA)  
Aperture Uncertainty (Jitter, tJ)  
Wake-Up Time3  
Full  
Full  
Full  
Full  
Full  
Full  
V
V
V
V
V
V
3.5  
7
1.0  
0.3  
7
ns  
Cycles  
ns  
ps rms  
ms  
OUT OF RANGE RECOVERY TIME  
2
Cycles  
1 With duty cycle stabilizer (DCS) enabled.  
2 Output propagation delay is measured from CLK 50% transition to DATA 50% transition, with 5 pF load.  
3 Wake-up time is dependant on the value of the decoupling capacitors; typical values shown with 0.1 µF and 10 µF capacitors on REFT and REFB.  
N+1  
N
N+2  
N+8  
N–1  
N+3  
tA  
ANALOG  
INPUT  
N+7  
N+4  
N+6  
N+5  
CLK  
DATA  
OUT  
N–9  
N–8  
N–7  
N–6  
N–5  
N–4  
N–3  
N–2  
N–1  
N
tPD = 6.0ns MAX  
2.0ns MIN  
03066-0-002  
Figure 2. Timing Diagram  
EXPLANATION OF TEST LEVELS  
Test Level Definitions  
I
100% production tested.  
II  
100% production tested at 25°C and guaranteed by design and characterization at specified temperatures.  
Sample tested only.  
Parameter is guaranteed by design and characterization testing.  
Parameter is a typical value only.  
III  
IV  
V
VI  
100% production tested at 25°C and guaranteed by design and characterization for industrial temperature range.  
Rev. A | Page 6 of 36  
 
 
 
 
 
 
AD9236  
ABSOLUTE MAXIMUM RATINGS  
Table 5. AD9236 Absolute Maximum Ratings  
THERMAL RESISTANCE  
Parameter  
ELECTRICAL  
AVDD  
DRVDD  
AGND  
AVDD  
D0–D11  
CLK, MODE AGND  
VIN+, VIN–  
VREF  
With Respect to Min Max  
Unit  
θJA is specified for the worst-case conditions on a 4-layer board  
in still air, in accordance with EIA/JESD51-1.  
AGND  
DGND  
DGND  
DRVDD  
DGND  
–0.3 +3.9  
–0.3 +3.9  
–0.3 +0.3  
–3.9 +3.9  
–0.3 DRVDD + 0.3  
–0.3 AVDD + 0.3  
–0.3 AVDD + 0.3  
–0.3 AVDD + 0.3  
–0.3 AVDD + 0.3  
–0.3 AVDD + 0.3  
–0.3 AVDD + 0.3  
V
V
V
V
V
V
V
V
V
V
V
Table 6. Thermal Resistance  
Package Type  
Unit  
θJA  
θJC  
RU-28  
CP-32  
67.7  
32.5  
°C/W  
°C/W  
32.71  
AGND  
AGND  
AGND  
AGND  
AGND  
Airflow increases heat dissipation effectively, reducing θJA. Also,  
more metal directly in contact with the package leads from  
metal traces, through holes, ground, and power planes reduces  
the θJA. It is recommended that the exposed paddle be soldered  
to the ground plane for the LFCSP package. There is an  
increased reliability of the solder joints, and maximum thermal  
capability of the package is achieved with the exposed paddle  
soldered to the customer board.  
SENSE  
REFT, REFB  
PDWN  
ENVIRONMENTAL  
Storage Temperature  
Operating Temperature Range  
Lead Temperature Range  
(Soldering 10 sec)  
Junction Temperature  
–65 +125  
–40 +85  
°C  
°C  
300  
150  
°C  
°C  
Stresses above those listed under Absolute Maximum Ratings  
may cause permanent damage to the device. This is a stress rat-  
ing only and functional operation of the device at these or any  
other conditions above those indicated in the operational sec-  
tion of this specification is not implied. Exposure to absolute  
maximum rating conditions for extended periods may affect  
device reliability.  
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 7 of 36  
 
AD9236  
DEFINITIONS OF SPECIFICATIONS  
Analog Bandwidth (Full Power 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.  
Effective Number of Bits (ENOB)—The effective number of  
bits for a sine wave input at a given input frequency can be cal-  
culated directly from its measured SINAD using the following  
formula:  
Aperture Delay (tA)—The delay between the 50% point of the  
rising edge of the clock and the instant at which the analog  
input is sampled.  
(
SINAD 1.76  
)
ENOB =  
6.02  
Signal-to-Noise Ratio (SNR)1 The ratio of the rms input  
signal amplitude to the rms value of the sum of all other spec-  
tral components below the Nyquist frequency, excluding the  
first six harmonics and dc.  
Aperture Uncertainty (Jitter, tJ)—The sample-to-sample varia-  
tion in aperture delay.  
Integral Nonlinearity (INL)—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.  
Spurious Free Dynamic Range (SFDR)1The difference in dB  
between the rms input signal amplitude and the peak spurious  
signal. The peak spurious component may or may not be a  
harmonic.  
Two-Tone SFDR1The 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.  
Differential Nonlinearity (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 miss-  
ing codes to 12-bit resolution indicates that all 4096 codes must  
be present over all operating ranges.  
Clock Pulsewidth and Duty Cycle—Pulsewidth high is the  
minimum amount of time that the clock pulse should be left in  
the Logic 1 state to achieve rated performance. Pulsewidth low  
is the minimum time the clock pulse should be left in the low  
state. At a given clock rate, these specifications define an accept-  
able clock duty cycle.  
Offset Error—The major carry transition should occur for an  
analog value 1/2 LSB below VIN+ = VIN–. Offset error is  
defined as the deviation of the actual transition from that point.  
Minimum Conversion Rate—The clock rate at which the SNR  
of the lowest analog signal frequency drops by no more than  
3 dB below the guaranteed limit.  
Gain Error—The first code transition should occur at an  
analog value 1/2 LSB above negative full scale. The last transi-  
tion should occur at an analog value 1 1/2 LSB below 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.  
Maximum Conversion Rate—The clock rate at which para-  
metric testing is performed.  
Output Propagation Delay (tPD)—The delay between the clock  
rising edge and the time when all bits are within valid logic  
levels.  
Temperature Drift—The temperature drift for offset error and  
gain error specifies the maximum change from the initial  
(25°C) value to the value at TMIN or TMAX  
.
Out-of-Range Recovery Time—The time it takes for the ADC  
to reacquire the analog input after a transition from 10% above  
positive full scale to 10% above negative full scale, or from 10%  
below negative full scale to 10% below positive full scale  
Power Supply Rejection Ratio—The change in full scale from  
the value with the supply at the minimum limit to the value  
with the supply at its maximum limit.  
Total Harmonic Distortion (THD)1The ratio of the rms  
input signal amplitude to the rms value of the sum of the first  
six harmonic components.  
1 AC specifications may be reported in dBc (degrades as signal levels are  
lowered) or in dBFS (always related back to converter full scale).  
Signal-to-Noise and Distortion (SINAD)1The ratio of the  
rms input signal amplitude to the rms value of the sum of all  
other spectral components below the Nyquist frequency, includ-  
ing harmonics but excluding dc.  
Rev. A | Page 8 of 36  
 
AD9236  
PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS  
OTR  
MODE  
SENSE  
VREF  
REFB  
REFT  
AVDD  
AGND  
VIN+  
1
2
3
4
5
6
7
8
9
28 D11 (MSB)  
27 D10  
26 D9  
DNC 1  
CLK 2  
DNC 3  
PDWN 4  
DNC 5  
DNC 6  
24 VREF  
23 SENSE  
22 MODE  
21 OTR  
20 D11 (MSB)  
19 D10  
25 D8  
24 DRVDD  
23 DGND  
22 D7  
AD9236  
CSP  
AD9236  
TOP VIEW  
TOP VIEW  
(Not to Scale)  
21 D6  
(Not to Scale)  
20 D5  
(LSB) D0 7  
D1 8  
18 D9  
17 D8  
VIN– 10  
AGND 11  
AVDD 12  
CLK 13  
19 D4  
18 D3  
17 D2  
16 D1  
PDWN 14  
15 D0 (LSB)  
03066-0-022  
03066-0-021  
Figure 4. 32-Lead LFCSP  
Figure 3. 28-Lead TSSOP  
Table 8. Pin Function Descriptions—  
32-Lead LFCSP (CP Package)  
Table 7. Pin Function Descriptions—  
28-Lead TSSOP (RU Package)  
Pin No.  
Mnemonic  
DNC  
Description  
Pin No.  
Mnemonic  
OTR  
MODE  
Description  
1, 3, 5, 6  
Do Not Connect  
1
2
Out-of-Range Indicator  
Data Format Select and DCS  
Mode Selection  
2
4
CLK  
PDWN  
D0 (LSB) to  
D11 (MSB)  
Clock Input Pin  
Power-Down Function Select  
Data Output Bits  
7–14,  
17–20  
3
4
5
6
7, 12  
8, 11  
9
10  
13  
14  
SENSE  
VREF  
REFB  
REFT  
AVDD  
AGND  
VIN+  
VIN–  
CLK  
PDWN  
D0 (LSB) to  
D11 (MSB)  
Reference Mode Selection  
Voltage Reference Input/Output  
Differential Reference (–)  
Differential Reference (+)  
Analog Power Supply  
Analog Ground  
Analog Input Pin (+)  
Analog Input Pin (–)  
Clock Input Pin  
Power-Down Function Select  
Data Output Bits  
15  
16  
21  
22  
DGND  
DRVDD  
OTR  
Digital Output Ground  
Digital Output Driver Supply  
Out-of-Range Indicator  
Data Format Select and DCS  
Mode Selection  
MODE  
23  
24  
25  
26  
27, 32  
28, 31  
29  
SENSE  
VREF  
REFB  
REFT  
AVDD  
AGND  
VIN+  
VIN–  
Reference Mode Selection  
Voltage Reference Input/Output  
Differential Reference (–)  
Differential Reference (+)  
Analog Power Supply  
Analog Ground  
15–22,  
25–28  
23  
24  
DGND  
DRVDD  
Digital Output Ground  
Digital Output Driver Supply  
Analog Input Pin (+)  
Analog Input Pin (–)  
30  
Rev. A | Page 9 of 36  
 
AD9236  
EQUIVALENT CIRCUITS  
AVDD  
DRVDD  
D11-D0,  
OTR  
VIN+, VIN–  
03600-0-005  
03600-0-003  
Figure 7. Equivalent Digital Output Circuit  
Figure 5. Equivalent Analog Input Circuit  
AVDD  
AVDD  
CLK,  
MODE  
PDWN  
20k  
03600-0-004  
03600-0-006  
Figure 6. Equivalent MODE Input Circuit  
Figure 8. Equivalent Digital Input Circuit  
Rev. A | Page 10 of 36  
 
AD9236  
TYPICAL PERFORMANCE CHARACTERISTICS  
AVDD = 3.0 V, DRVDD = 2.5 V, Sample Rate = 80 MSPS, DCS Disabled, TA = 25°C, 2 V p-p Differential Input, AIN = –0.5 dBFS,  
VREF = 1.0 V External, unless otherwise noted  
0
–10  
100  
90  
80  
70  
60  
50  
40  
AIN = –0.5dBFS  
SNR = 71.0dBc  
ENOB = 11.5 BITS  
SFDR = 93.6dBc  
SFDR (dBFS)  
–20  
–30  
SFDR (dBc)  
–40  
SFDR = 90dB  
–50  
REFERENCE LINE  
–60  
–70  
SNR (dBFS)  
–80  
SNR (dBc)  
–90  
–100  
–110  
–120  
0
0
0
5
10  
15  
20  
25  
30  
35  
40  
40  
40  
–30  
–25  
–20  
–15  
–10  
–5  
0
FREQUENCY (MHz)  
INPUT AMPLITUDE (dBFS)  
03066-0-031  
03066-0-048  
Figure 9. Single Tone 8K FFT @ 2.5 MHz  
Figure 12. Single Tone SNR/SFDR vs. Input Amplitude (AIN) @ 2.5 MHz  
0
–10  
100  
AIN = –0.5dBFS  
SFDR (dBFS)  
SNR = 70.6dBc  
ENOB = 11.4 BITS  
SFDR = 87.8dBc  
–20  
90  
–30  
SFDR (dBc)  
–40  
80  
SFDR = 90dB  
REFERENCE LINE  
–50  
–60  
70  
–70  
SNR (dBFS)  
SNR (dBc)  
–80  
60  
–90  
–100  
–110  
–120  
50  
40  
5
10  
15  
20  
25  
30  
35  
–30  
–25  
–20  
–15  
–10  
–5  
0
FREQUENCY (MHz)  
INPUT AMPLITUDE (dBFS)  
03066-0-032  
03066-0-049  
Figure 10. Single Tone 8K FFT @ 39 MHz  
Figure 13. Single Tone SNR/SFDR vs. Input Amplitude (AIN) @ 39 MHz  
0
–10  
100  
AIN = –0.5dBFS  
SNR = 70.1dBc  
ENOB = 11.3 BITS  
SFDR = 81.9dBc  
SFDR (DIFF)  
–20  
90  
–30  
–40  
SFDR (SE)  
80  
–50  
SNR (DIFF)  
–60  
–70  
70  
–80  
SNR (SE)  
–90  
60  
–100  
–110  
–120  
50  
5
10  
15  
20  
25  
30  
35  
0
20  
40  
60  
80  
100  
FREQUENCY (MHz)  
SAMPLE RATE (MSPS)  
03066-0-033  
03066-0-042  
Figure 11. Single Tone 8K FFT @ 70 MHz  
Figure 14. SNR/SFDR vs. Sample Rate @ 10 MHz  
Rev. A | Page 11 of 36  
 
 
AD9236  
0
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
SFDR (dBFS)  
AIN = –6.5dBFS  
SNR = 71.3dBFS  
SFDR = 92.5dBc  
100  
90  
80  
70  
60  
50  
40  
SFDR (dBc)  
SNR (dBFS)  
SNR (dBc)  
SFDR = 90dB  
REFERENCE LINE  
–120  
0
–30  
–27  
–24  
–21  
–18  
–15  
–12  
–9  
–6  
5
10  
15  
20  
25  
30  
35  
40  
INPUT AMPLITUDE (dBFS)  
FREQUENCY (MHz)  
03066-0-039  
03066-0-036  
Figure 18. Two-Tone SNR/SFDR vs. Input Amplitude @ 30 MHz and 31 MHz  
Figure 15. Two-Tone 8K FFT @ 30 MHz and 31 MHz  
0
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
100  
AIN = –6.5dBFS  
SNR = 71.0dBFS  
SFDR = 79.3dBc  
SFDR (dBFS)  
90  
SFDR (dBc)  
80  
70  
SNR (dBFS)  
60  
SFDR = 90dB  
REFERENCE LINE  
SNR(dBc)  
50  
–120  
0
40  
5
10  
15  
20  
25  
30  
35  
40  
–30  
–27  
–24  
–21  
–18  
–15  
–12  
–9  
–6  
FREQUENCY (MHz)  
INPUT AMPLITUDE (dBFS)  
03066-0-037  
03066-0-040  
Figure 16. Two-Tone 8K FFT @ 69 MHz and 70 MHz  
Figure 19. Two-Tone SNR/SFDR vs. Input Amplitude @ 69 MHz and 70 MHz  
1.0  
0.8  
1.0  
0.8  
0.6  
0.6  
0.4  
0.4  
0.2  
0.2  
0
0
–0.2  
–0.4  
–0.6  
–0.8  
–0.2  
–0.4  
–0.6  
–0.8  
–1.0  
–1.0  
0
1024  
2048  
3072  
4096  
0
1024  
2048  
3072  
4096  
CODE  
CODE  
03066-0-038  
03066-0-041  
Figure 17. Typical INL  
Figure 20. Typical DNL  
Rev. A | Page 12 of 36  
AD9236  
72.0  
71.5  
71.0  
70.5  
70.0  
69.5  
69.0  
68.5  
68.0  
100  
95  
90  
85  
80  
75  
70  
–40°C  
–40°C  
+85°C  
+25°C  
+25°C  
+85°C  
0
25  
50  
75  
100  
125  
0
25  
50  
75  
100  
125  
INPUT FREQUENCY (MHz)  
INPUT FREQUENCY (MHz)  
03066-0-045  
03066-0-047  
Figure 21. SNR vs. Input Frequency  
Figure 24. SFDR vs. Input Frequency  
95  
0
SFDR (DCS ON)  
–10  
90  
85  
80  
75  
70  
65  
60  
55  
–20  
–30  
SFDR (DCS OFF)  
–40  
–50  
SNR (DCS OFF)  
–60  
–70  
–80  
–90  
SNR (DCS ON)  
–100  
–110  
–120  
30  
35  
40  
45  
50  
55  
60  
65  
70  
0
7.68  
15.36  
FREQUENCY (MHz)  
23.04  
30.72  
DUTY CYCLE (%)  
03066-0-046  
03066-0-061  
Figure 22. SNR/SFDR vs. Clock Duty Cycle  
Figure 25. 32K FFT WCDMA Carrier @ FIN =76.8 MHz:  
Sample Rate = 61.44 MSPS  
0
–10  
–20  
–30  
–40  
–50  
–60  
–70  
–80  
–90  
–100  
–110  
–120  
0
7.68  
15.36  
23.04  
30.72  
FREQUENCY (MHz)  
03066-0-060  
Figure 23.32K FFT CDMA-2000 Carrier @ FIN = 46.08 MHz:  
Sample Rate = 61.44 MSPS  
Rev. A | Page 13 of 36  
 
AD9236  
THEORY OF OPERATION  
The AD9236 architecture consists of a front-end sample-and-  
hold amplifier (SHA) followed by a pipelined switched capaci-  
tor ADC. The pipelined ADC is divided into three sections,  
consisting of a 4-bit first stage followed by eight 1.5-bit stages  
and a final 3-bit flash. Each stage provides sufficient overlap to  
correct for flash errors in the preceding stages. The quantized  
outputs from each stage are combined into a final 12-bit result  
in the digital correction logic. The pipelined architecture per-  
mits the first stage to operate on a new input sample, while the  
remaining stages operate on preceding samples. Sampling  
occurs on the rising edge of the clock.  
Referring to Figure 27, the clock signal alternately switches the  
SHA between sample mode and hold mode. When the SHA is  
switched into sample mode, the signal source must be capable  
of charging the sample capacitors and settling within one-half  
of a clock cycle. A small resistor in series with each input can  
help reduce the peak transient current required from the output  
stage of the driving source. Also, a small shunt capacitor can be  
placed across the inputs to provide dynamic charging currents.  
This passive network creates a low-pass filter at the ADCs  
input; therefore, the precise values are dependant upon the  
application. In IF undersampling applications, any shunt capaci-  
tors should be reduced or removed. In combination with the  
driving source impedance, they would limit the input  
bandwidth.  
Each stage of the pipeline, excluding the last, consists of a low  
resolution flash ADC 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 stage to facilitate digital correction  
of flash errors. The last stage simply consists of a flash ADC.  
H
T
T
5pF  
5pF  
VIN+  
VIN–  
C
C
PAR  
PAR  
The input stage contains a differential SHA that can be ac- or  
dc-coupled in differential or single-ended modes. The output-  
staging block aligns the data, carries out the error correction,  
and passes the data to the output buffers. The output buffers are  
powered from a separate supply, allowing adjustment of the  
output voltage swing. During power-down, the output buffers  
go into a high impedance state.  
T
T
H
03066-0-012  
Figure 27. Switched-Capacitor SHA Input  
ANALOG INPUT AND REFERENCE OVERVIEW  
The analog input to the AD9236 is a differential switched  
capacitor SHA that has been designed for optimum perform-  
ance while processing a differential input signal. The SHA input  
can support a wide common-mode range (VCM) and maintain  
excellent performance, as shown in Figure 26. An input com-  
mon-mode voltage of midsupply minimizes signal-dependant  
errors and provides optimum performance.  
For best dynamic performance, the source impedances driving  
VIN+ and VIN– should be matched such that common-mode  
settling errors are symmetrical. These errors are reduced by the  
common-mode rejection of the ADC.  
An internal differential reference buffer creates positive and  
negative reference voltages, REFT and REFB, that define the  
span of the ADC core. The output common mode of the refer-  
ence buffer is set to midsupply, and the REFT and REFB volt-  
ages and span are defined as follows:  
100  
95  
SFDR (2.5MHz)  
90  
85  
1
2
1
REFT =  
REFB =  
AVDD +VREF  
( )  
SFDR (39MHz)  
80  
(
AVDD VREF  
)
75  
2
SNR (2.5MHz)  
Span = 2×  
(
REFT REFB  
)
= 2×VREF  
70  
SNR (39MHz)  
65  
60  
55  
50  
It can be seen from the equations above that the REFT and REFB  
voltages are symmetrical about the midsupply voltage and, by defi-  
nition, the input span is twice the value of the VREF voltage.  
0.5  
1.0  
1.5  
2.0  
2.5  
3.0  
The internal voltage reference can be pin strapped to fixed val-  
ues of 0.5 V or 1.0 V, or adjusted within the same range as dis-  
cussed in the Internal Reference Connection section. Maximum  
SNR performance is achieved with the AD9236 set to the largest  
COMMON-MODE LEVEL (V)  
03066-0-016  
Figure 26. SNR, SFDR vs. Common-Mode Level  
Rev. A | Page 14 of 36  
 
 
 
AD9236  
input span of 2 V p-p. The relative SNR degradation is 3 dB  
when changing from 2 V p-p mode to 1 V p-p mode.  
AVDD  
VIN+  
33  
The SHA may be driven from a source that keeps the signal  
peaks within the allowable range for the selected reference volt-  
age. The minimum and maximum common-mode input levels  
are defined as  
2V p-p  
49.9Ω  
10pF  
33Ω  
AD9236  
VIN–  
AGND  
1kΩ  
1kΩ  
VREF  
0.1µF  
VCMMIN  
=
03600-0-014  
2
Figure 29. Differential Transformer-Coupled Configuration  
(
AVDD +VREF  
)
VCMMAX  
=
2
The signal characteristics must be considered when selecting  
a transformer. Most RF transformers saturate at frequencies  
below a few MHz, and excessive signal power can also cause  
core saturation, which leads to distortion.  
The minimum common-mode input level allows the AD9236 to  
accommodate ground referenced inputs.  
Although optimum performance is achieved with a differential  
input, a single-ended source may be applied to VIN+ or VIN–.  
In this configuration, one input accepts the signal, while the  
opposite input should be set to midscale by connecting it to an  
appropriate reference. For example, a 2 V p-p signal may be  
applied to VIN+ while a 1 V reference is applied to VIN–. The  
AD9236 then accepts an input signal varying between 2 V and  
0 V. In the single-ended configuration, distortion performance  
may degrade significantly as compared to the differential case.  
However, the effect is less noticeable at lower input frequencies.  
Single-Ended Input Configuration  
A single-ended input may provide adequate performance in  
cost-sensitive applications. In this configuration, there is a deg-  
radation in SFDR and distortion performance due to the large  
input common-mode swing (see Figure 14). However, if the  
source impedances on each input are matched, there should be  
little effect on SNR performance. Figure 30 details a typical sin-  
gle-ended input configuration.  
Differential Input Configurations  
1k  
AVDD  
VIN+  
33  
As previously detailed, optimum performance is achieved while  
driving the AD9236 in a differential input configuration. For  
baseband applications, the AD8138 differential driver provides  
excellent performance and a flexible interface to the ADC. The  
output common-mode voltage of the AD8138 is easily set to  
AVDD/2, and the driver can be configured in a Sallen Key filter  
topology to provide band limiting of the input signal.  
0.33µF  
1k  
2V p-p  
49.9  
20pF  
33  
AD9236  
1k  
+
VIN–  
AGND  
10  
µF  
0.1  
µ
F
1k  
03600-A-015  
Figure 30. Single-Ended Input Configuration  
CLOCK INPUT CONSIDERATIONS  
1V p-p  
49.9  
Typical high speed ADCs use both clock edges to generate a  
variety of internal timing signals, and as a result may be sensi-  
tive to clock duty cycle. Commonly a 5% tolerance is required  
on the clock duty cycle to maintain dynamic performance char-  
acteristics. The AD9236 contains a clock duty cycle stabilizer  
(DCS) that retimes the nonsampling edge, providing an internal  
clock signal with a nominal 50% duty cycle. This allows a wide  
range of clock input duty cycles without affecting the perform-  
ance of the AD9236. As shown in Figure 22, noise and distor-  
tion performance is nearly flat for a 30% to 70% duty cycle with  
the DCS on.  
499Ω  
AVDD  
VIN+  
33Ω  
499Ω  
523Ω  
20pF  
AD8138  
499Ω  
AD9236  
1kΩ  
1kΩ  
33Ω  
VIN–  
AGND  
0.1µF  
03066-0-013  
Figure 28. Differential Input Configuration Using the AD8138  
At input frequencies in the second Nyquist zone and above, the  
performance of most amplifiers is not adequate to achieve the  
true performance of the AD9236. This is especially true in IF  
undersampling applications where frequencies in the 70 MHz  
to 100 MHz range are being sampled. For these applications,  
differential transformer coupling is the recommended input  
configuration. The value of the shunt capacitor is dependent  
on the input frequency and source impedance and should be  
reduced or removed. An example is shown in Figure 29.  
The duty cycle stabilizer uses a delay-locked loop (DLL) to cre-  
ate the nonsampling edge. As a result, any changes to the sam-  
pling frequency require approximately 100 clock cycles to allow  
the DLL to acquire and lock to the new rate.  
Rev. A | Page 15 of 36  
 
 
 
AD9236  
425  
400  
375  
350  
325  
300  
140  
120  
100  
80  
JITTER CONSIDERATIONS  
ANALOG CURRENT  
TOTAL POWER  
High speed, high resolution ADCs are sensitive to the quality of  
the clock input. The degradation in SNR at a given input fre-  
quency (fINPUT) due only to aperture jitter (tJ) can be calculated  
with the following equation:  
SNR= 20log  
[
2πfINPUT ×tJ  
]
60  
40  
In the equation, the rms aperture jitter represents the root-mean  
square of all jitter sources, which include the clock input, analog  
input signal, and ADC aperture jitter specification. IF under-  
sampling applications are particularly sensitive to jitter (see  
Figure 31).  
20  
DIGITAL CURRENT  
0
10  
20  
30  
40  
50  
60  
70  
80  
90  
100  
SAMPLE RATE (MSPS)  
03066-0-044  
The clock input should be treated as an analog signal in cases  
where aperture jitter may affect the dynamic range of the  
AD9236. Power supplies for clock drivers should be separated  
from the ADC 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 other meth-  
ods), it should be retimed by the original clock at the last step.  
Figure 32. Power and Current vs. Sample Rate @ 2.5 MHz  
Reducing the capacitive load presented to the output drivers  
can minimize digital power consumption. The data in Figure 32  
was taken with the same operating conditions as the Typical  
Performance Characteristics, and with a 5 pF load on each  
output driver.  
By asserting the PDWN pin high, the AD9236 is placed in  
standby mode. In this state, the ADC typically dissipates  
1 mW if the CLK and analog inputs are static. During  
standby, the output drivers are placed in a high impedance  
state. Reasserting the PDWN pin low returns the AD9236  
to its normal operational mode.  
75  
70  
0.2ps  
65  
60  
55  
50  
45  
40  
MEASURED  
SNR  
0.5ps  
Low power dissipation in standby mode is achieved by shutting  
down the reference, reference buffer, and biasing networks. The  
decoupling capacitors on REFT and REFB are discharged when  
entering standby mode and then must be recharged when  
returning to normal operation. As a result, the wake-up time is  
related to the time spent in standby mode, and shorter standby  
cycles result in proportionally shorter wake-up times. With the  
recommended 0.1 µF and 10 µF decoupling capacitors on REFT  
and REFB, it takes approximately 1 second to fully discharge the  
reference buffer decoupling capacitors and 7 ms to restore full  
operation.  
1.0ps  
1.5ps  
2.0ps  
2.5ps  
3.0ps  
1
10  
100  
1000  
INPUT FREQUENCY (MHz)  
03066-0-043  
Figure 31. SNR vs. Input Frequency and Jitter  
POWER DISSIPATION AND STANDBY MODE  
As shown in Figure 32, the power dissipated by the AD9236 is  
proportional to its sample rate. The digital power dissipation is  
determined primarily by the strength of the digital drivers and  
the load on each output bit. The maximum DRVDD current  
(IDRVDD) can be calculated as  
DIGITAL OUTPUTS  
The AD9236 output drivers can be configured to interface with  
2.5 V or 3.3 V logic families by matching DRVDD to the digital  
supply of the interfaced logic. The output drivers are sized to  
provide sufficient output current to drive a wide variety of logic  
families. However, large drive currents tend to cause current  
glitches on the supplies that may affect converter performance.  
Applications requiring the ADC to drive large capacitive loads  
or large fanouts may require external buffers or latches.  
IDRVDD = VDRVDD ×CLOAD × fCLK ×N  
where N is the number of output bits, 12 in the case of the  
AD9236. This maximum current occurs when every output bit  
switches on every clock cycle, i.e., a full-scale square wave at the  
Nyquist frequency, fCLK/2. In practice, the DRVDD current will  
be established by the average number of output bits switching,  
which will be determined by the sample rate and the character-  
istics of the analog input signal.  
As detailed in Table 10, the data format can be selected for  
either offset binary or twos complement.  
Rev. A | Page 16 of 36  
 
 
 
AD9236  
TIMING  
In all reference configurations, REFT and REFB drive the A/D  
conversion core and establish its input span. The input range of  
the ADC always equals twice the voltage at the reference pin for  
either an internal or an external reference.  
The AD9236 provides latched data outputs with a pipeline delay  
of seven clock cycles. Data outputs are available one propaga-  
tion delay (tPD) after the rising edge of the clock signal. Refer to  
Figure 2 for a detailed timing diagram.  
VIN+  
The length of the output data lines and the loads placed on  
them should be minimized to reduce transients within the  
AD9236. These transients can degrade the converters dynamic  
performance.  
VIN–  
REFT  
0.1µF  
+
ADC  
0.1µF  
REFB  
0.1µF  
10µF  
CORE  
The lowest typical conversion rate of the AD9236 is 1 MSPS. At  
clock rates below 1 MSPS, dynamic performance may degrade.  
VREF  
0.1µF  
+
10µF  
VOLTAGE REFERENCE  
SELECT  
LOGIC  
A stable and accurate 0.5 V voltage reference is built into the  
AD9236. The input range can be adjusted by varying the refer-  
ence voltage applied to the AD9236 using either the internal  
reference or an externally applied reference voltage. The input  
span of the ADC tracks reference voltage changes linearly. The  
various reference modes are summarized in Table 9 and  
described in the following sections.  
SENSE  
0.5V  
AD9236  
03066-A-017  
Figure 33. Internal Reference Configuration  
If the ADC is being driven differentially through a transformer,  
the reference voltage can be used to bias the center tap (com-  
mon-mode voltage).  
If the internal reference of the AD9236 is used to drive multiple  
converters to improve gain matching, the loading of the refer-  
ence by the other converters must be considered. Figure 34  
depicts how the internal reference voltage is affected by loading.  
INTERNAL REFERENCE CONNECTION  
A comparator within the AD9236 detects the potential at the  
SENSE pin and configures the reference into four possible  
states, which are summarized in Table 9. If SENSE is grounded,  
the reference amplifier switch is connected to the internal resis-  
tor divider (see Figure 33), setting VREF to 1 V. Connecting the  
SENSE pin to VREF switches the reference amplifier output to  
the SENSE pin, completing the loop and providing a 0.5 V ref-  
erence output. If a resistor divider is connected as shown in  
Figure 35, the switch is again set to the SENSE pin. This puts the  
reference amplifier in a noninverting mode with the VREF out-  
put defined as follows:  
0.05  
0
–0.05  
0.5V ERROR (%)  
–0.10  
1.0V ERROR (%)  
–0.15  
–0.20  
–0.25  
R2  
R1  
VREF = 0.5× 1+  
0
0.5  
1.0  
1.5  
LOAD (mA)  
2.0  
2.5  
3.0  
03066-0-019  
Figure 34. VREF Accuracy vs. Load  
Table 9. Reference Configuration Summary  
Internal Switch  
Position  
Resulting Differential  
Span (V p-p)  
Selected Mode  
SENSE Voltage  
AVDD  
VREF  
Resulting VREF (V)  
External Reference  
Internal Fixed Reference  
Programmable Reference  
N/A  
SENSE  
SENSE  
N/A  
0.5  
2 × External Reference  
1.0  
2 × VREF  
0.2 V to VREF  
R2  
R1  
(See Figure 35)  
0.5 × 1 +  
Internal Fixed Reference  
AGND to 0.2 V  
Internal Divider  
1.0  
2.0  
Rev. A | Page 17 of 36  
 
 
 
 
AD9236  
OPERATIONAL MODE SELECTION  
VIN+  
VIN–  
As discussed earlier, the AD9236 can output data in either offset  
binary or twos complement format. There is also a provision for  
enabling or disabling the clock duty cycle stabilizer (DCS). The  
MODE pin is a multilevel input that controls the data format  
and DCS state. The input threshold values and corresponding  
mode selections are outlined in Table 10.  
REFT  
0.1µF  
0.1µF  
REFB  
0.1µF  
+
ADC  
10µF  
CORE  
VREF  
+
Table 10. Mode Selection  
10µF  
0.1µF  
SELECT  
LOGIC  
Duty Cycle  
R2  
MODE Voltage  
AVDD  
Data Format  
Stabilizer  
Disabled  
Enabled  
Enabled  
Disabled  
SENSE  
Twos Complement  
Twos Complement  
Offset Binary  
2/3 AVDD  
R1  
0.5V  
1/3 AVDD  
AGND (Default)  
Offset Binary  
AD9236  
03066-0-018  
EVALUATION BOARD  
Figure 35. Programmable Reference Configuration  
The AD9236 evaluation board provides all of the support cir-  
cuitry required to operate the ADC in its various modes and  
configurations. Complete schematics and layout plots follow  
and demonstrate the proper routing and grounding techniques  
that should be applied at the system level.  
EXTERNAL REFERENCE OPERATION  
The use of an external reference may be necessary to enhance  
the gain accuracy of the ADC or to improve thermal drift char-  
acteristics. When multiple ADCs track one another, a single  
reference (internal or external) may be necessary to reduce gain  
matching errors to an acceptable level. Figure 36 shows the typi-  
cal drift characteristics of the internal reference in both 1.0 V  
and 0.5 V modes.  
It is critical that signal sources with very low phase noise (< 1 ps  
rms jitter) be used to realize the ultimate performance of the  
converter. Proper filtering of the input signal, to remove har-  
monics and lower the integrated noise at the input, is also nec-  
essary to achieve the specified noise performance.  
When the SENSE pin is tied to AVDD, the internal reference is  
disabled, allowing the use of an external reference. An internal  
reference buffer loads the external reference with an equivalent  
7 kΩ load. The internal buffer still generates the positive and  
negative full-scale references, REFT and REFB, for the ADC  
core. The input span is always twice the value of the reference  
voltage; therefore, the external reference must be limited to a  
maximum of 1.0 V.  
TSSOP Evaluation Board  
Figure 37 shows the typical bench setup used to evaluate the ac  
performance of the AD9236. The AD9236 can be driven single-  
ended or differentially through an AD8138 driver or a trans-  
former. Separate power pins are provided to isolate the DUT  
from the support circuitry. Each input configuration can be  
selected by proper connection of various jumpers (refer to the  
schematics).  
1.0  
0.9  
0.8  
0.7  
0.6  
The AUXCLK input should be selected in applications requiring  
the lowest jitter and SNR performance (i.e., IF undersampling  
characterization). It allows the user to apply a clock input signal  
that is 4× the target sample rate of the AD9236. A low jitter,  
differential divide-by-4 counter, the MC100LVEL33D, provides  
a 1× clock output that is subsequently returned back to the CLK  
input via JP9. For example, a 260 MHz signal (sinusoid) will be  
divided down to a 65 MHz signal for clocking the ADC. Note  
that R1 must be removed with the AUXCLK interface. Lower  
jitter is often achieved with this interface since many RF signal  
generators display improved phase noise at higher output fre-  
quencies and the slew rate of the sinusoidal output signal is 4×  
that of a 1× signal of equal amplitude.  
V
= 1.0V  
0.5  
0.4  
0.3  
0.2  
0.1  
0
REF  
V
= 0.5V  
REF  
–40 –30 –20 –10  
0
10 20 30 40 50 60 70 80  
TEMPERATURE (°C)  
03066-0-011  
Figure 36. Typical VREF Drift  
Rev. A | Page 18 of 36  
 
 
 
AD9236  
An alternative differential analog input path using an AD8351  
op amp is included in the layout but is not populated in produc-  
tion. Designers interested in evaluating the op amp with the  
ADC should remove C15, R12, and R3 and populate the op amp  
circuit. The passive network between the AD8351 outputs and  
the AD9236 allows the user to optimize the frequency response  
of the op amp for their application.  
LFCSP Evaluation Board  
The typical bench setup used to evaluate the ac performance of  
the AD9236 is similar to the TSSOP evaluation board connec-  
tions (refer to the schematics for connection details). The  
AD9236 can be driven single-ended or differentially through a  
transformer. Separate power pins are provided to isolate the  
DUT from the support circuitry. Each input configuration can  
be selected by proper connection of various jumpers (refer to  
the schematics).  
3V  
3V  
3V  
3V  
+
+
+
+
AVDD GND DUT GND DUT  
DVDD  
J1  
S4  
AVDD  
DRVDD  
HP8644, 2V p-p  
BAND-PASS  
FILTER  
REFIN  
XFMR  
INPUT  
SIGNAL SYNTHESIZER  
DATA  
CAPTURE  
AND  
AD9236  
EVALUATION BOARD  
PROCESSING  
CLOCK  
10MHz  
S1  
HP8644, 2V p-p  
DIVIDER  
REFOUT  
CLOCK  
CLOCK SYNTHESIZER  
03066-0-024  
Figure 37. TSSOP Evaluation Board Connections  
Rev. A | Page 19 of 36  
AD9236  
Figure 38. TSSOP Evaluation Board Schematic, DUT  
Rev. A | Page 20 of 36  
AD9236  
T O C E R J S  
N O L E A E  
M
G H T R R I A N G A L D E H E E  
1N5712  
1 2 5 7 1 N  
Figure 39. TSSOP Evaluation Board Schematic, Clock Inputs and Output Buffering  
Rev. A | Page 21 of 36  
AD9236  
Figure 40. TSSOP Evaluation Board Schematic, Analog Inputs  
Rev. A | Page 22 of 36  
AD9236  
DACLK  
DVDD  
1
2
3
4
5
6
7
8
9
10  
11  
12  
13  
14  
28  
DD0  
DD1  
DD2  
DD3  
DD4  
DD5  
DD6  
DD7  
DD8  
DD9  
DD10  
DD11  
MSB–DB11  
DB10  
DB19  
CLOCK  
DVDD  
DCOM  
NC3  
C30  
C31  
27  
26  
25  
24  
23  
22  
21  
20  
19  
18  
17  
16  
15  
0.1µF  
0.01µF  
C46  
C29  
0.01µF  
0.1µF  
DB8  
AD9762  
DB7  
DB6  
DB5  
DB4  
DB3  
DB2  
DB1  
DB0  
NC1  
NC2  
AVDD  
TP18  
WHT  
S6  
COMP2  
IOUTA  
IOUTB  
ACOM  
COMP1  
FSADJ  
REFIO  
REFLO  
SLEEP  
U4  
C56  
R29  
0.01µF  
49.9Ω  
C55  
22pF  
C51  
0.01µF  
R28  
R30  
49.9Ω  
2kΩ  
C54  
C49  
22pF  
0.01µF  
03066-0-010  
Figure 41. TSSOP Evaluation Board Schematic, Optional D/A Converter  
03066-0-025  
Figure 42. TSSOP Evaluation Board Layout, Primary Side  
Rev. A | Page 23 of 36  
AD9236  
03066-0-026  
Figure 43. TSSOP Evaluation Board Layout, Secondary Side  
03066-0-027  
Figure 44. TSSOP Evaluation Board Layout, Ground Plane  
Rev. A | Page 24 of 36  
AD9236  
03066-0-028  
Figure 45. TSSOP Evaluation Board Layout, Power Plane  
03066-0-029  
Figure 46. TSSOP Evaluation Board Layout, Primary Silkscreen  
Rev. A | Page 25 of 36  
AD9236  
03066-0-030  
Figure 47. TSSOP Evaluation Board Layout, Secondary Silkscreen  
Rev. A | Page 26 of 36  
AD9236  
P 2  
0 V 5 .  
5 V 2 .  
P
L
V A M  
V D  
G N D  
5 V 2 .  
0 V 3 .  
D D V D R  
G N D  
D D A V  
D 8  
D 9  
D 1 0  
D 1  
1 7  
1 8  
1 9  
2 0  
2 1  
2 2  
2 3  
2 4  
8
D 0 7  
D N C  
6
D N C  
5
D 1 1  
O T  
R
E
N W P D  
4
D N C  
3
M O D  
S E S E N  
E F V R  
C L K  
2
D N C  
1
Figure 48. LFCSP Evaluation Board Schematic, Analog Inputs and DUT  
Rev. A | Page 27 of 36  
AD9236  
Figure 49. LFCSP Evaluation Board Schematic, Digital Path  
Rev. A | Page 28 of 36  
AD9236  
Figure 50. LFCSP Evaluation Board Schematic, Clock Input  
Rev. A | Page 29 of 36  
AD9236  
03066-0-055  
03066-0-053  
Figure 53. LFCSP Evaluation Board Layout, Ground Plane  
Figure 51. LFCSP Evaluation Board Layout, Primary Side  
03066-0-054  
03066-0-056  
Figure 52. LFCSP Evaluation Board Layout, Secondary Side  
Figure 54. LFCSP Evaluation Board Layout, Power Plane  
Rev. A | Page 30 of 36  
AD9236  
03066-0-057  
03066-0-058  
Figure 55. LFCSP Evaluation Board Layout, Primary Silkscreen  
Figure 56. LFCSP Evaluation Board Layout, Secondary Silkscreen  
Rev. A | Page 31 of 36  
AD9236  
Table 11. LFCSP Evaluation Board Bill of Materials  
Recommended  
Package Value Vendor/Part Number  
Supplied  
by ADI  
Item Qty. Omit1 Reference Designator  
Device  
C1, C5, C7, C8, C9, C11,  
C12, C13, C15, C16, C31,  
C33, C34, C36, C37, C41,  
18  
1
Chip Capacitor  
0603  
0.1 µF  
C43, C47  
C6, C18, C27, C17, C28,  
C35, C45, C44  
8
C2, C3, C4, C10, C20, C22,  
C25, C29  
C46, C24  
8
2
3
Tantalum Capacitor  
Chip Capacitor  
TAJD  
0603  
10 µF  
2
C14, C30, C32, C38, C39,  
C40, C48, C49  
8
0.001 µF  
4
5
3
1
C19, C21, C23  
C26  
Chip Capacitor  
Chip Capacitor  
0603  
0603  
10 pF  
10 pF  
E31, E35, E43, E44, E50,  
E51, E52, E53  
9
2
1
6
Header  
EHOLE  
Jumper Blocks  
2
E1, E45  
J1, J2  
L1  
7
8
SMA Connector/50 Ω  
Inductor  
SMA  
0603  
1
10 nH Coilcraft/0603CS-10NXGBU  
Wieland/25.602.2653.0,  
z5-530-0625-0  
9
P2  
Terminal Block  
TB6  
10  
1
5
P12  
Header Dual 20-Pin RT Angle HEADER40  
Digi-Key S2131-20-ND  
R3, R12, R23, R28, RX  
11  
Chip Resistor  
0603  
0 Ω  
R37, R22, R42, R16, R17,  
R27  
6
12  
13  
2
R4, R15  
Chip Resistor  
Chip Resistor  
0603  
0603  
33 Ω  
1 kΩ  
R5, R6, R7, R8, R13, R20,  
R21, R24, R25, R26, R30,  
R31, R32, R36  
14  
14  
15  
2
1
R10, R11  
R29  
Chip Resistor  
Chip Resistor  
0603  
0603  
36 Ω  
50 Ω  
1
R19  
Digi-Key  
220 Ω  
16  
2
RP1, RP2  
Resistor Pack  
ADT1-1WT  
R_742  
CTS/742C163220JTR  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
1
1
1
1
1
T1  
AWT1-1T  
Mini-Circuits  
U1  
74LVTH162374 CMOS Register TSSOP-48  
U4  
AD9236BCP ADC (DUT)  
74VCX86M  
CSP-32  
SOIC-14  
PCB  
Analog Devices, Inc.  
Fairchild  
X
U5  
PCB  
AD92XXBCP/PCB  
AD8351 Op Amp  
MACOM Transformer  
Chip Resistor  
Analog Devices, Inc.  
Analog Devices, Inc.  
X
X
1
1
5
3
2
1
1
U3  
MSOP-8  
T2  
ETC1-1-13 1-1 TX MACOM/ETC1-1-13  
R9, R1, R2, R38, R39  
R18, R14, R35  
R40, R41  
0603  
0603  
0603  
SELECT  
25 Ω  
Chip Resistor  
Chip Resistor  
10 kΩ  
1.2 kΩ  
100 Ω  
R34  
Chip Resistor  
R33  
Chip Resistor  
Total 82 34  
1 These items are included in the PCB design, but are omitted at assembly.  
Rev. A | Page 32 of 36  
 
AD9236  
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 57. 28-Lead Thin Shrink Small Outline Package [TSSOP] (RU-28)—Dimensions shown in millimeters  
5.00  
0.60 MAX  
BSC SQ  
0.60 MAX  
PIN 1  
INDICATOR  
25  
24  
32  
1
PIN 1  
INDICATOR  
0.50  
BSC  
3.25  
4.75  
TOP  
BOTTOM  
VIEW  
BSC SQ  
3.10 SQ  
2.95  
VIEW  
0.50  
0.40  
0.30  
17  
16  
8
9
0.25 MIN  
3.50 REF  
0.80 MAX  
12° MAX  
0.65 TYP  
0.05 MAX  
0.02 NOM  
1.00  
0.85  
0.80  
0.30  
0.23  
0.18  
COPLANARITY  
0.08  
0.20 REF  
SEATING  
PLANE  
COMPLIANT TO JEDEC STANDARDS MO-220-VHHD-2  
Figure 58. 32-Lead Frame Chip Scale Package [LFCSP] (CP-32-1)—Dimensions shown in millimeters  
ORDERING GUIDE  
AD9236 Products  
AD9236BRU-80  
AD9236BRURL7-80  
AD9236BRUZ-801  
AD9236BRUZRL7-801  
AD9236BCP-802  
AD9236BCPRL7-802  
AD9236BCPZ-801, 2  
AD9236BCPZRL7-801, 2  
AD9236BRU-80EB  
AD9236BCP-80EB2  
Temperature Range  
–40°C to +85°C  
–40°C to +85°C  
–40°C to +85°C  
–40°C to +85°C  
–40°C to +85°C  
–40°C to +85°C  
–40°C to +85°C  
–40°C to +85°C  
Package Description  
Package Outline  
Thin Shrink Small Outline (TSSOP)  
Thin Shrink Small Outline (TSSOP)  
Thin Shrink Small Outline (TSSOP)  
Thin Shrink Small Outline (TSSOP)  
Lead Frame Chip Scale (LFCSP)  
Lead Frame Chip Scale (LFCSP)  
Lead Frame Chip Scale (LFCSP)  
Lead Frame Chip Scale (LFCSP)  
TSSOP Evaluation Board  
RU-28  
RU-28  
RU-28  
RU-28  
CP-32-1  
CP-32-1  
CP-32-1  
CP-32-1  
LFCSP Evaluation Board  
1 Z = Lead Free.  
2 It is recommended that the exposed paddle be soldered to the ground plane for the LFCSP package. There is an increased reliability of the solder joints, and the maxi-  
mum thermal capability of the package is achieved with the exposed paddle soldered to the customer board.  
Rev. A | Page 33 of 36  
 
 
 
 
 
AD9236  
NOTES  
Rev. A | Page 34 of 36  
AD9236  
NOTES  
Rev. A | Page 35 of 36  
AD9236  
NOTES  
© 2003 Analog Devices, Inc. All rights reserved. Trademarks and regis-  
tered trademarks are the property of their respective owners.  
C03066-0-10/03(A)  
Rev. A | Page 36 of 36  

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