Group delay approximation of allpass digital filters by transforming the desired response
T. Matsunaga, Masaaki Ikehara · 2004
In this paper, we present a new design method of allpass digital filters with equiripple group delay response. This method is based on solving a least squares solution iteratively. At each iteration, the desired group delay response is transformed so as to have equiripple error. By this method, an equiripple solution is obtained very quickly with less computational complexity.