Synthesis of RC active filters using controlled sources

Abstract

A new synthesis procedure employing only unity-gain controlled sources is introduced, by which the denominator polynomial of a voltage transfer function can be decomposed in two ways. One of these gives a prescribed pole sensitivity, the modulus and argument of which can easily be controlled. The other gives a pole sensitivity that can be optimised by Calahan's RC-RL decomposition. A modification of the basic configuration gives a very stable, simple and insensitive circuit for realising lowpass or bandpass transfer functions. Synthesis of positive-real-axis transmission zeros is possible if an additional voltage invertor is used. The new method is compared with Hakim's circuit and with the RC-gyrator cascade circuit. The paper includes three design examples.