AD9239 Analog Devices, AD9239 Datasheet - Page 20

• Manufacturer Part Number: AD9239
• Description: Quad, 12-Bit, 170 MSPS/210 MSPS/250 MSPS Serial Output 1.8 V ADC
• Manufacturer: Analog Devices

Specifications of AD9239

• Resolution (bits): 12bit
• # Chan: 4
• Sample Rate: 250MSPS
• Interface: Ser
• Analog Input Type: Diff-Uni,SE-Uni
• Ain Range: 1.25 V p-p
• Adc Architecture: Pipelined
• Pkg Type: CSP

AD9239
For applications where SNR is a key parameter, differential
transformer coupling is the recommended input configuration
(see Figure 47 to Figure 49), to achieve the true performance of
the AD9239.
Regardless of the configuration, the value of the shunt capacitor, C,
is dependent on the input frequency and may need to be reduced
or removed.
1.25V p-p
1.25V p-p
*C
DIFF IS OPTIONAL
1.25V p-p
Figure 47. Differential Transformer-Coupled Configuration
Figure 48. Differential Transformer-Coupled Configuration
Figure 49. Differential Transformer-Coupled Configuration
65Ω
L
50Ω
0.1μF
0.1μF
0.1µF
for Narrow-Band IF Applications
for Wideband IF Applications
1:1 Z RATIO
1:1 Z RATIO
ADT1-1WT
1:1 Z RATIO
ADT1-1WT
for Baseband Applications
ADT1-1WT
0.1μF
0.1μF
0.1μF
250Ω
250Ω
33Ω
33Ω
*C
L
L
33Ω
33Ω
DIFF
C
C
2.2pF
33Ω
33Ω
L
VIN + x
VIN – x
VIN + x
VIN – x
AD9239
AD9239
ADC
ADC
VIN + x
VIN – x
AD9239
ADC
AGND
Rev. B | Page 20 of 40
Single-Ended Input Configuration
A single-ended input may provide adequate performance in
cost-sensitive applications. In this configuration, SFDR and
distortion performance can degrade due to input common-mode
swing mismatch. If the application requires a single-ended input
configuration, ensure that the source impedances on each input
are well matched in order to achieve the best possible performance.
A full-scale input of 1.25 V p-p can be applied to the ADC’s
VIN + x pin while the VIN − x pin is terminated. Figure 51
details a typical single-ended input configuration.
1.25V p-p
1.25V p-p
0.1µF
Figure 50. Differential Balun-Coupled Configuration
BALUN
1:1 Z
0.1µF
49.9Ω
Figure 51. Single-Ended Input Configuration
for Wideband IF Applications
BALUN
1:1 Z
0.1µF
25Ω
0.1µF
0.1µF
66Ω
33Ω
33Ω
*C
*C
DIFF
DIFF IS OPTIONAL
33Ω
4.7pF
33Ω
C
C
VIN + x
VIN – x
VIN + x
VIN – x
AD9239
ADC
AD9239
ADC