Design of 1-D Stable Variable Fractional Delay IIR Filters Using Finite Impulse Response Fitting

In this paper, a novel finite impulse response fitting-based approach for the design of 1-D stable variable fractional delay IIR filters is proposed. The design algorithm is decomposed into three design stages: Firstly, a set of fixed delay FIR filters is designed by using Weighted Least-Squares method. Then, the related set of fixed delay stable IIR filters is determined via finite impulse response fitting. Finally, the design result is obtained by fitting each of the fixed delay IIR filter coefficients as 1-D polynomials. It is shown that the proposed method always guarantees the filter obtained to be stable and has very low computation complexity comparable with that of designing fixed FIR filters. Two illustrative design examples are given to justify the effectiveness and advantages over other existing approaches for designing variable fractional delay IIR filters.