Preliminary Technical Data

ADA4938-1

Rev. PrD | Page 9 of 14

OPERATIONAL DESCRIPTION

DEFINITION OF TERMS

Figure 4. Circuit Definitions

Differential Voltage

This refers to the difference between two node voltages. For

example, the output differential voltage (or equivalently, output

differential-mode voltage) is defined as

−OUT terminals with respect to a common reference.

Common-Mode Voltage

This refers to the average of two node voltages. The output

common-mode voltage is defined as

Balance

Balance is a measure of how well differential signals are

matched in amplitude and are exactly 180° 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.

dm

OUT

cm

OUT

V

V

Error

Balance

Output

,

,

=