An all-pass filter is an electronic filter that passes all frequencies equally, but changes the phase relationship between various frequencies. It does this by varying its propagation delay with frequency. Generally, the filter is described by the frequency at which the phase shift crosses 90°.

They are generally used to compensate for other undesired phase shifts that arise in the system.

See also

• Digital filter Another realization of an all-pass filter
• High-pass filter
• Low-pass filter
• Band-stop filter
• Band-pass filter

Linear filters | Digital signal processing