Low-complexity Design of Variable Fractional Delay Filters

Abstract

In order to design variable fractional delay filters with low complexity and high accuracy, an efficient design method with controllable cut-off frequency is proposed, which integrates the analytic all-phase filter design, the cubic spline interpolation and Taylor series expansion. In the proposed design, not only the time delay of the filter can be precisely adjusted by setting the delay parameter, but also the tap coefficients of each subfilter in the Farrow structure can be rapidly configured via setting the cut-off frequency parameter, thus the cut-off frequency of the filter can be adjusted flexibly. Numerical simulations show that, the proposed method is especially suitable to design variable fractional delay filters with low or middle cut-off frequencies, and its computation complexity is one order of magnitude lower than that of the existing Weighted Least Squares (WLS) design.