Datasheet

Data Sheet AD8338
Rev. A | Page 19 of 20
INTERFACING THE AD8338 TO AN ADC
The AD8338 is well suited to drive a high speed analog-to-digital
converter (ADC) and is compatible with many ADCs from Analog
Devices. This example illustrates the interfacing of the AD8338 to
the AD7450. The AD7450 is a low power, 3.0 V
ADC, which is
al
so competitively priced for a low cost total solution.
Figure 50 shows the basic connections between the AD8338
and the AD7450. The common-mode voltage provided by the
AD8338 is within the specifications of the AD7450.
The AD8338 can be coupled directly to the AD7450 for full
dc-to-18 MHz operation at the highest level of performance with
low operating power (160 mW typical). The glueless interface
enables a physically small, high performance data acquisition
system that is ideal for many field instruments. A filter before
the VGA provides the antialiasing function and noise limiting.
In applications where the modulated information is not encoded
in the signal amplitude, use the AGC feature of the AD8338 to
reduce any bit errors in the sampled signal.
Figure 50. Basic Connections to the AD7450 ADC
INPR
INMR
FILTER
OUTPUT
VREF
OUTP
OUTM
C1
0.1µF
COMM
DETO
OFSN
C2
0.1µF
MODE
VBAT
3.0V
U1
AD8338
GAIN
GAIN
CONTROL
U2
AD7450
GND
3.0V
C3
0.1µF
3.0V
C4
0.1µF
R1
5.1Ω
V
DD
V
REF
SCLK
SDATA
CS
TO
MICRO-
CONTROLLER
V
IN+
V
IN–
C4
0.1µF
11279-149