AD9432 Analog Devices, AD9432 Datasheet - Page 15

• Manufacturer Part Number: AD9432
• Description: 12-Bit, 105 MSPS Analog-to-Digital Converter
• Manufacturer: Analog Devices

Specifications of AD9432

• Resolution (bits): 12bit
• # Chan: 1
• Sample Rate: 105MSPS
• Interface: Par
• Analog Input Type: Diff-Uni
• Ain Range: 2 V p-p
• Adc Architecture: Pipelined
• Pkg Type: QFP

APPLICATIONS INFORMATION
USING THE AD8138 TO DRIVE THE AD9432
The
AD9432 in dc-coupled applications. The AD8138 was specifically
designed for ADC driver applications. Superior SNR performance
is maintained up to analog frequencies of 30 MHz. The AD8138
op amp provides single-ended-to-differential conversion, which
allows for a low cost alternative to transformer coupling for ac
applications, as well.
The circuit in Figure 29 was breadboarded, and the measured
performance is shown in Figure 30 and Figure 31. These figures
are for ±5 V supplies at the AD8138; with a single 5 V supply at
the AD8138, performance dropped by about 1 dB to 2 dB.
Figure 30 shows SNR and SINAD for a −1 dBFS analog input
frequency varied from 2 MHz to 40 MHz with an encode rate
of 105 MSPS. The measurements are for nominal conditions
at room temperature. Figure 31 shows the second-order and
third-order harmonic distortion performance under the same
conditions.
The dc common-mode voltage for the AD8138 outputs can be
adjusted via the V
voltage that the AD9432 inputs require.
VIN
AD8138
25Ω
50Ω
500Ω
500Ω
differential output op amp can be used to drive the
Figure 29. AD8138/AD9432 Schematic
OCM
input to provide the 3 V common-mode
V
500Ω
OCM
AD8138
10pF
10pF
500Ω
50Ω
50Ω
22pF
3kΩ
5V
2kΩ
AIN
AIN
AD9432
0.1µF
Rev. F | Page 15 of 16
Figure 31. Measured Second-Order and Third-Order Harmonic Distortion
–100
–70
–80
–90
66
65
64
63
62
60
Figure 30. Measured SNR and SINAD (Encode = 105 MSPS)
61
0
0
H2
(Encode = 105 MSPS)
20
20
SINAD
SNR
AIN (MHz)
AIN (MHz)
H3
40
40
AD9432
60
60