Lattice wave digital filter design for arbitrarily specified amplitude characteristics by phase approximation

The amplitude specification can be formulated in a form of a phase specification for prototype or non-prototype lattice Wave Digital Filters (WDF). The approximation problem is solved by generating arbitrary phase polynomials via an interpolation algorithm and by applying the Remez-exchange algorithm. The approximation method results in filters with equiripple amplitude both in the pass band and stop band. The approximation in the pass band and stop band are carried out simultaneously. The iteration is simple, converging in a few steps. Design examples illustrate the efficiency of the proposed design method in the pass band, stop band and transition band