Design of equiripple minimum phase FIR-filters

The numerical robustness and applicability of a recent approach to the design of minimum phase FIR filters by cascading a passband and a stopband filter [Go 80] is improved by the following measures: i) Spectral factorization (root finding) is avoided by exploiting the Hilbert relations between attenuation and phase ii) Unbounded gain in don´t care regions is restricted by prescription of appropriate desired values. As a result, highly selective minimum phase FIR filters requiring a considerably reduced number of multiplications are obtained.