When a signal passes through a serpentine trace with
coupling between the legs, there is an apparent
speed-up of the signal. That is, the signal appears to
pass through the serpentine section faster than the
trace length would otherwise indicate. This apparent
speed-up is caused by crosstalk coupling between the
legs of the serpentine traces. The amount of apparent
speed-up is directly related to the coupling strength
between the legs and inversely related to the rise time
of the signal passing through the section. The
apparent speed-up of the signal is not directly related
to the coupled length. For long coupled lengths (those
longer than the critical length) signals may become
distorted as they pass through the serpentine section,
but the degree of distortion is a complex function of
the frequency of the signal. Signals pass relatively
undistorted through short coupled serpentine sections.