Electrical tunable multiple-mode universal biquadratic circuits

This paper introduces electronically tunable multiple-mode universal biquadratic circuits employing operational trans-conductance amplifiers (OTAs) and grounded capacitors. The basic current-mode circuit configuration is obtained from a second-order integrator loop structure consisting of loss-less integrators. The multiple-mode biquadratic circuits are constructed with additional OTAs to the current-mode one. The circuits can realize low-pass, bandpass, high-pass, band-stop and all-pass transfer functions by suitably choosing the input and output terminals without any component matching conditions. Additionally, the circuit parameters ω₀, Q and H can be set orthogonally or independently through adjusting the bias currents of the OTAs. The biquadratic circuit is verified by using PSPICE simulation program.