A realization of highpass, bandstop and allpass transfer functions without external passive elements

摘要

This paper introduces a way to realize highpass, bandstop and allpass transfer functions using Operational Amplifiers (OAs) and Operational Transconductance Amplifiers (OTAs). The basic circuit configuration is constructed with two OAs and five OTAs only. And the circuit parameters can be independently set and electronically tuned by adjusting the transconductance gains of OTAs. Although the circuit configuration has already been known, it seems that the feature for realizing the highpass, the bandpass and the allpass transfer functions makes the structure more attractive and useful. An example is given together with simulated results by PSpice.