All-pass filters

All-pass filters transmit all frequencies at a gain factor of 1. All-pass filters only change the phase of the sinusoidal input signals. They are used for phase correction and to delay signals.

Bode diagram of an all-pass filter
Bode diagram of an all-pass filter

Notice

notice

When the parameters of an all-pass filter are defined, the Bessel filter prototype should be parameterised because it approximates a constant group run time for all frequencies.

The group run time is the time that a "group" of cos-shaped oscillations takes when passing through a transmission system.