Realization of electronically tunable first-order allpass filter using single-ended OTAs

A new of voltage-mode first-order allpass filter using only three single-ended operational transconductance amplifiers (OTAs) and one capacitor is proposed. The pole frequency can be controlled electronically by adjusting the transconductance value of the OTA. Moreover, for realizing first-order allpass reposed no any conditions of component-matching are required. The characteristics of the proposed filter circuit are also simulated using PSPICE simulations to verify the theory.