Electronically tunable voltage-mode universal filter using simple OTAs

This paper presents a new voltage-mode universal filter with single-input multiple-output employing seven simple CMOS operational transconductance amplifiers, two grounded capacitors and one resistor. The proposed filter can realize lowpass, bandpass, highpass, bandstop and allpass voltage responses from the same topology. The natural frequency (ω_o) and the quality factor (Q) can be controlled orthogonally and electronically by adjusting the bias currents of OTAs. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.