Independently tunable voltage-mode OTA-C biquadratic filter with five inputs and three outputs and its fully-uncoupled quadrature sinusoidal oscillator application

Abstract

This paper presents an independently tunable five-input and three-output voltage-mode biquadratic filter using five single-ended output operational transconductance amplifiers (OTAs) and two grounded capacitors. The proposed circuit can be connected to the input terminals in different ways to form a lowpass, bandpass, highpass, bandreject and allpass filter. Unlike the previously reported works, the proposed circuit can realize both non-inverting/inverting lowpass, bandpass, and bandreject filtering responses. The proposed circuit not only allows for the orthogonal controllability of the resonance angular frequency (ωo) and quality factor (Q), but also achieves independent controllability of the parameters ωo and ωo/Q without the need for control factor matching conditions. The new circuit has the following advantages: single-input three-output biquadratic filter or five-input single-output biquadratic filter with single topology, electronic tunable of parameters ωo, Q, and ωo/Q, high input impedance, resistorless structure, and no need for inverted input signals. Moreover, as an application, a quadrature sinusoidal oscillator with fully-uncoupled electronically controllable both frequency of oscillation and condition of oscillation is designed using the proposed filter. The workability of the proposed circuits is validated by OrCAD PSpice simulation program and experimental results. The given results are consistent with theoretical expectations.