Optimal design of IIR frequency-response-masking filters using second-order cone programming

The frequency-response-masking (FRM) technique proposed by Lim (1986) has proven effectiveness for the design of very sharp digital filters with reduced implementation complexity compared to other options. In this paper, we propose a constrained optimization method for the design of basic and multistage FRM filters where the prototype filters are of infinite-impulse response (IIR) with prescribed pole radius. The design is accomplished through a sequence of linear updates for the design variables with each update carried out using second-order cone programming. Computer simulations have demonstrated that the class of IIR FRM filters investigated in the paper offers an attractive alternative to its finite-impulse response counterpart in terms of filter performance, system delay, and realization complexity.