Design of biquad filters with a single current follower

Abstract

Five new configurations of single current–follower–biquad (SCFB) filters are presented. They can synthesise second-order highpass, lowpass, bandpass, allpass, and notch filtering functions using a single current follower connected to four or more passive one-port RC elements. We have calculated the active and passive sensitivities to evaluate the circuit performance. The natural frequencies and the quality factors of most resulting SCFB filters will be insensitive to the current tracking error of the current follower. Experimental results which agree with theoretical analysis are obtained.