High input impedance voltage mode universal biquad filter

Abstract

A high input impedance voltage mode universal biquad filter using two operational transconductance amplifiers (OTAs), one current feedback amplifier (CFA), two capacitors and one grounded resistor has been studied. The new circuit has three inputs and single output and can realize all the standard filter functions, that is low pass (LP), high pass (HP), band pass (BP), notch (NH), and all pass (AP) filters without changing the circuit topology. The proposed circuit offers several advantages such as orthogonal controllability of the resonance frequency w₀and quality factor <i>Q</i>. There is no need of one more active element for the realization of all pass filter, high input impedance and low output impedance which is suitable for cascading for higher order filter transfer functions and low active and passive sensitivity performance.