AD8131
OPERATIONAL DESCRIPTION
R
F
Common-mode voltage refers to the average of two node
voltages. The output common-mode voltage is defined as
R
G
+IN
–OUT
AD8131
+OUT
+D
IN
–OUT
VOUT,cm V+OUT + V−OUT 2
=
R
V
V
L, dm
OCM
OUT, dm
+OUT
–D
IN
–IN
R
G
Balance is a measure of how well differential signals are
matched in amplitude and exactly 180 degrees apart in phase.
Balance is most easily determined by placing a well-matched
resistor divider between the differential voltage nodes and
comparing the magnitude of the signal at the divider’s midpoint
with the magnitude of the differential signal. By this definition,
output balance is the magnitude of the output common-mode
voltage divided by the magnitude of the output differential-
mode voltage.
R
F
Figure 39. Circuit Definitions
Differential voltage refers to the difference between two node
voltages. For example, the output differential voltage (or
equivalently output differential-mode voltage) shown in
Figure 39 is defined as
VOUT,dm
=
V+OUT − V−OUT
VOUT, cm
Output Balance Error =
VOUT, dm
V
+OꢀT and V–OꢀT refer to the voltages at the +OꢀT and −OꢀT
terminals with respect to a common reference.
Rev. B | Page 15 of 20
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