Linear phase IIR filter design: a model reduction approach

A method is presented for the design of a linear-phase IIR filter. It involves designing a FIR filter satisfying the given frequency response specifications and subsequently obtaining a significantly lower-order IIR filter using model reduction. The method is illustrated by a design example and is compared with a direct method for the design of linear-phase IIR filters using equalizers. The filter designed using the proposed technique gives a better constant group delay for an almost equal order.<>