A recursive digital filter with maximally flat linear phase at an arbitrary specified frequency
P. Thajchayapong, P. Lomtong · Proceedings of the IEEE · 1978
An available recursive digital low-pass filter with constant group delay cannot be spectral transformed to give, for example, a bandpass filter which also has constant group delay. This correspondence describes a technique, using Gauss-Jordan elimination, to design a recursive digital filter with maximally flat linear phase at an arbitrary specified frequency.