LEAST-SQUARES APPROACH TO IIR DIGITAL-FILTERS AND AN APPLICATION TO EQUIRIPPLE SOLUTIONS

This paper formulates the modified least-squares method presented by M ullis in a general form so that weighting can be applied. Then, an alg orithm is proposed with which a least-squares approximation can be der ived for an IIR digital filter, by solving iteratively a system of equ ations. The method is extended to a complex Chebyshev approximation th at minimizes the maximum magnitude of the complex en or, by multiplyin g the weight, which is newly derived in this paper, with the modified least-squares error. The method is compared with a conventional comple x Chebyshev approximation by means of a computer simulation and the ef fectiveness of the proposed method is demonstrated. (C) 1998 Scripta T echnica.