Datasheet

AD8131
Rev. B | Page 15 of 20
OPERATIONAL DESCRIPTION
AD8131
R
G
R
G
R
F
R
F
R
L, dm
V
OUT, dm
–OUT
+OUT
–OUT
+OUT
+IN
–IN
+D
IN
–D
IN
V
OCM
01072-039
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
(
)
OUTOUT
dmOUT
VVV
+
=
,
V
+OUT
and V
–OUT
refer to the voltages at the +OUT and −OUT
terminals with respect to a common reference.
Common-mode voltage refers to the average of two node
voltages. The output common-mode voltage is defined as
(
)
2
, OUTOUTcmOUT
VVV
+
+
=
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.
dmOUT
cmOUT
V
V
ErrorBalanceOutput
,
,
=