The optimal and straightforward design of bandpass wave digital lattice filters with arbitrary loss specifications

An efficient, simple and reliable design method is introduced for bandpass wave digital lattice filters exhibiting arbitrary loss responses. The main feature of this method is that the approximation is straightforward. Thus it is carried out without the need to apply frequency transformation techniques. The method relies on employing the relationship between the amplitude and the two branch phase functions of the filter. As a consequence, the whole problem reduces finally to constructing a polynomial specified by its phase. The generation of this polynomial is achieved through the use of interpolation recurrence formulae. By factorizing this polynomial into its Hurwitz and non-Hurwitz parts, the two branch allpass functions are determined and realized. (C) 1997 by John Wiley & Sons, Ltd.