Selective linear-phase filters with controllable amplitude response

A method is presented for the construction of transfer functions of analog or digital filters exhibiting linear phase low-pass or bandpass characteristics. The group delay which is determined by the denominator polynomial can be maximally flat or equiripple in the whole or part of the passband. The passband loss as well as the stopband loss can be monotonic or have ripples with arbitrary widths. The iterative procedure involves the solutions to a polynomial and a set of linear equations.