Designing peak-constrained arbitrary-phase FIR digital filters with low passband-to-stopband energy ratio

An approach for approximating nonrecursive digital filters with arbitrary phase is proposed. The method compromises maximum stopband attenuation and minimum stopband energy. The approach is based on a time-varying weight function which is made constant, at each iteration, inside a given frequency interval. In that sense, a partially WLS-like and partially equiripple stopband is achieved