Datasheet

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DATA CONVERTERS
V
IN
-
+
-
+
DV
DD
V
OCM
AV
SS
AV
DD
A
IN2
A
IN1
V
DD
V
ref
5 V
V
CC
0.1 µF
-5 V
V
CC
-
V
IN
-
+
-
+
DV
DD
V
OCM
AV
SS
AV
DD
A
IN2
A
IN1
V
DD
V
ref
5 V
V
CC
0.1 µF
V
IN
-
+
-
+
DV
DD
V
OCM
AV
SS
AV
DD
A
IN
A
IN
V
DD
V
ref
5 V
V
CC
0.1 µF
V
CC
R
PU
V
CC
R
PU
R
g
R
g
V
P
R
f
R
f
V
OUT
V
OUT
THS4140
THS4141
SLOS320F – MAY 2000 – REVISED JANUARY 2006
APPLICATION INFORMATION (continued)
Data converters are one of the most popular applications for the fully differential amplifiers. Figure 22 shows a
typical configuration of a fully differential amplifier attached to a differential ADC.
Figure 22. Fully Differential Amplifier Attached to a Differential ADC
Fully differential amplifiers can operate with a single supply. V
OCM
defaults to the midrail voltage, V
CC
/2. The
differential output may be fed into a data converter. This method eliminates the use of a transformer in the
circuit. If the ADC has a reference voltage output (V
ref
), then it is recommended to connect it directly to the V
OCM
of the amplifier using a bypass capacitor for stability. For proper operation, the input common-mode voltage to
the input terminal of the amplifier should not exceed the common-mode input voltage range.
Figure 23. Fully Differential Amplifier Using a Single Supply
Some single supply applications may require the input voltage to exceed the common-mode input voltage range.
In such cases, the following circuit configuration is suggested to bring the common-mode input voltage within the
specifications of the amplifier.
Figure 24. Circuit With Improved Common-Mode Input Voltage
12
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