Tunable Voltage-Mode Multifunction Biquadratic Filter with Three Inputs Single Output Using Three Single-Ended OTAs and Two Capacitors

This paper presents a electronically tunable voltage-mode universal biquadratic filter with three inputs and one output using three single-ended operational transconductance amplifiers and two capacitors. The proposed filter provides low-pass, band-pass, high-pass, band-stop and all-pass filters by appropriately connecting the input terminals. No component-matching condition is required for realizing these filtering functions. The use of minimum elements makes the filter possible for low power consumption applications. The natural frequency and the quality factor can be set orthogonally by adjusting the circuit components. Also the natural frequency can be electronically tuned via the bias currents of OTAs. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.