Design of very sharp recursive digital filters using the frequency response masking technique

Abstract

This thesis focuses on designing infinite-impulse response (IIR) digital filters based on the frequency response masking (FRM) approach. The proposed method is different from previous methods of designing IIR digital filters based on FRM approach in both structural and algorithmic aspects. In this thesis, both the bandedge shaping filters and masking filters are recursive filters realized in the form of wave digital filters. The overall filter is optimized jointly using semi-infinite programming. Bounded input bounded output (BIBO) stability is ensured by imposing constraints on the multiplier coefficients during the optimization process. The formulae of respective bandedges of subfilters are presented. The effects of the frequency responses of the subfilters on the magnitude response of the overall filter are analyzed. Some examples are also presented.