On the design of adjustable fractional delay FIR filters

This brief considers minimax design of adjustable fractional delay finite-impulse response (FIR) filters. We employ a filter structure that, in the paper by Vesma and Saramaki in 1997, is referred to as the modified Farrow structure which makes use of a number of linear-phase FIR subfilters. Previously, only the cases where all subfilters are of equal order have been considered. In this brief, we propose a design technique that in general produces subfilters of different orders which results in a lower overall arithmetic complexity. Design examples are included, illustrating the efficiency of the proposed design technique.