Electronically tunable multiple-input single-output voltage-mode multifunction filter employing simple CMOS OTAs

This paper describes a new electronically tunable four inputs and single output voltage-mode universal biquadratic filter based on simple CMOS operational transconductance amplifiers (OTAs) and grounded capacitors. The proposed filter provides low-pass, high-pass, band-pass, band-stop and all-pass voltage responses at a high impedance input terminal, which enable easy cascadability. The circuit parameters ω_o and Q can be orthogonally set the circuit component. The parameter ω_o also offers an electronic control by adjusting the transconductance gain of the OTA. For realizing all the filter responses, no critical component matching condition is required and all the parameter sensitivities are low. PSPICE simulation results are performed to confirm the theoretical analysis.