Design of IIR digital filters with critical monotonic passband amplitude characteristic: A case study

Abstract

A case study is reported related to the design of IIR digital filters exhibiting critical monotonic amplitude characteristic (CMAC) in the pass band. This kind of amplitude characteristic offers several advantages as compared to its non-monotonic counterparts, although it has not been studied thoroughly so far, if at all. After giving a short overview of the way of CMACs generation, arguments will be listed in favor of the IIR version of the digital filter function realization. Next, the IIR implementation of the digital filters will be considered in short. The main part of the paper will be devoted to the design sequence of this kind of filters which will be illustrated on the example of a band-pass filter obtained by a set of transformations from an all-pole low-pass analogue prototype. This will be the first time a CMAC band-pass IIR digital filter is reported.