Voltage Differencing Transconductance Amplifier-Based Quadrature Oscillator and Biquadratic Filter Realization with All Grounded Passive Elements

Abstract

The work realizes the sinusoidal quadrature oscillator and biquadratic filter with the same configuration using merely two voltage differencing transconductance amplifiers (VDTAs) as active devices and one grounded resistor and two grounded capacitor as passive elements. Performing the quadrature oscillator, the realized circuit is capable of producing two quadrature voltage outputs with almost equal amplitudes, and an independent electronic control of oscillation condition and oscillation frequency. Operating in voltage-mode biquadratic filter, the circuit can simultaneously generate the bandpass and lowpass filtering functions without any matching constraints. The natural angular frequency and the quality factor of the filter are independently and electronically adjustable. The effects of the VDTA non-idealities are also investigated in detail. Simulation results with TSMC 0.25 μm CMOS technology validate both working functions of the proposed circuit.