Electronically Tunable Third-Order Quadrature Oscillator Using VDTAs

This study proposes a new electronically tunable third-order quadrature oscillator using two multi-output voltage difference transconductance amplifiers (VDTAs) and three grounded capacitors. The proposed circuit provides three quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance current output with controllable amplitude. The proposed circuit can provide amplitude modulation/amplitude shift keying signals when the input bias current of the second VDTA is a modulating signal. The oscillation condition and oscillation frequency can be separately adjusted by the input bias currents of two multi-output VDTAs, and it is suitable for use on custom sensor networks. Experimental and H-Spice simulation results are given to confirm theoretical analyses.