The Approximation with Rational Functions of Prescribed Magnitude and Phase Characteristics

A successive-approximations method is applied to the selection of network functions having desired magnitude and phase variation with frequency. The first approxination, the first set of pole and zero locations, can be selected on the basis of known solutions to similar problems or through use of a set of curves. In succeeding approximations the pole and zero locations are adjusted to decrease the deviation of the earlier approximations from the desired characteristics. The process adjusts the magnitude and phase characteristics simultaneously. Its flexibility permits accommodation of practical constraints not possible with other methods.