CCCDTAs-based Versatile Quadrature Oscillator and Universal Biquad Filter

In this article, a novel circuit, which can function both as quadrature oscillator and universal biquad filter (lowpass, highpass and bandpass functions) is introduced. The features of the circuit are that, working as quadrature oscillator, the oscillation condition and oscillation frequency can be adjusted independently with the input bias currents: functioning as universal biquad filter, the quality factor and natural frequency can be tuned orthogonally via the input bias currents: the circuit can work as either the quadrature oscillator or the universal biquad filter without changing circuit topology: it provides output signals both in current-mode and voltage-mode simultaneously. The circuit description is very simple, consisting of merely 2 Current Controlled Current Differencing Transconducatance Amplifiers (CCCDTAs), 1 voltage buffer and 2 grounded capacitors. Without any external resistors and using only grounded elements, this circuit is then suitable for IC architecture. The PSPICE simulation results are depicted. The given results agree well with the theoretical anticipation. The circuit was biased with ±1.5V supply voltages.