Least-squares approximation to wide-band constant delay
Herman J. Blinchikoff, M. Savetman · IEEE Transactions on Circuit Theory · 1972
A new class of wide-band arithmetically symmetrical bandpass filters whose transfer-function poles are optimally calculated so that each filter's group delay is a least-squares approximation to a constant delay over the entire 3-dB bandwidth is derived. Furthermore, the value of this mean delay is optimized. Ladder network element values, attenuation responses, and delay responses are presented.