In signal processing, a comb filter is a filter implemented by adding a delayed version of a signal to itself, causing constructive and destructive interference. The frequency response of a comb filter consists of a series of regularly spaced notches in between regularly spaced peaks (sometimes called teeth) giving the appearance of a comb.
Comb filters exist in two forms, feedforward and feedback; which refer to the direction in which signals are delayed before they are added to the input.
Comb filters may be implemented in discrete time or continuous time forms which are very similar.