Design of FIR filters with complex desired frequency response usinga generalized Remez algorithm

摘要

Complex approximation with a generalized Remez algorithm is usednto design FIR digital filters with nonconjugate symmetric frequencynresponses. The minimax criterion is used and the Chebychev approximationnis posed as a linear optimization problem. The primal problem isnconverted to its dual and is solved using an efficient, quadraticallynconvergent algorithm developed by Tang. Optimal Chebychevnreal-coefficient FIR filters with group delay smaller than half thenfilter length can be designed with slightly better magnitude responsesncompared to linear-phase filters. Linear-phase filters can also bendesigned when the group delay is specified to be half the filter length.nMost importantly, the design method is capable of producing filters withncomplex coefficients that approximate nonconjugate symmetric frequencynresponses