Minimax phase error design of allpass variable fractional-delay digital filters by iterative weighted least-squares method

In this paper, an iterative weighted least-squares (LS) method is proposed for the design of allpass variable fractional-delay (VFD) digital filters, so that the maximum absolute phase error can be minimized. Meanwhile, it is found that the range of variable parameter will affect overall performance of the designed filter, which will be analyzed and discussed in this paper through several examples designed by least-squares and iterative weighted least-squares methods. And the stability of the designed filters and the effectiveness of the proposed iterative method are also revealed by these presented examples.