Electronically tunable first-order all pass sections using OTAs

This paper introduces electronically tunable voltage-mode and current-mode first-order all pass sections (APSs) employing operational trans-conductance amplifiers (OTAs) and grounded capacitor. The circuits can realize two all pass characteristics by choosing the current output of the OTA. Additionally, the circuit parameters ω₀ and H can be set independently through adjusting the bias currents of the OTAs electronically. Some examples are given together with simulated results by PSPICE.