Electronically tunable voltage-mode universal filter using simple CMOS OTAs

A new electronically tunable voltage-mode biquadratic filter with single input and five outputs using eight simple operational transconductance amplifiers and two grounded capacitors is presented. The proposed filter provides lowpass, bandpass, highpass, bandstop, and allpass voltage responses at a high input impedance terminal, which enables easy cascadability of the voltage circuit. The parameters natural frequency and the quality factor can be set orthogonally by adjusting the circuit components. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.