On the approximation problem in nonrecursive digital filter design

A new class of selective nonrecursive digital filters with a maximally flat frequency response in the passband and stopband is introduced. The proposed design method is based on a special solution of the general Hermite polynomial interpolation and allows computation of the parameters of these filters in closed form. Therefore it yields some advantage over numerical iterative methods. Design examples are given and an extension to the design of unsymmetrical bandpass systems is made.