A maximally flat group delay recursive digital filter with improved passband magnitude response
P. Thajchayapong, F. Cheevasuvit · Proceedings of the IEEE · 1979
A technique is proposed for the design of a recursive digital filter with maximally flat responses in both magnitude and group delay. In comparison to the previous designs [1]-[3], the magnitude and group delay always show smooth responses no matter what the difference is in the polynomial degrees of the numerator and denominator.