Design of stable IIR filters in the complex domain by automatic delay selection

A major problem when designing infinite impulse response (IIR) filters in the complex domain is ensuring that the filter is stable, especially when the IIR filter approximates the inverse of a non-minimum phase system, as is often the case for equalisation filters. Adding delay to the target frequency response can result in a stable filter, but up to now selecting that delay has been a matter of trial and error. This paper presents an automated method for finding this delay