
A system or subsystem with linear amplitude response
has a transfer function whose output plots as a straight-
line function of its input; departure from this condition
is differential gain error. Amplitude nonlinearity could
be characterized directly by the departure of the
transfer function from a straight line; ADC and DAC
components and subsystems are specified this way.
However, in video, amplitude nonlinearity is usually
characterized by a parameter
differential gain
(DG) that
is easier to measure.
To measure DG, you present to a system the sum of
a high-frequency signal and a low-frequency ...