Sinusoidal quadrature oscillator using voltage differencing gain amplifiers (VDGAs)

An alternative topology of voltage-mode sinusoidal quadrature oscillator based on VDGA (voltage differencing gain amplifier) is proposed. The proposed quadrature oscillator consisting of two VDGAs and two grounded capacitors with the absence of the external passive resistors can generate two sinusoidal output voltages with 90° phase difference. The oscillation condition and oscillation frequency (ωo) of the circuit are controllable independently through the transconductance gains of the VDGAs. Moreover, the proposed circuit configuration requires minimum of active and passive components, and also exhibits low sensitivity performance. Computer simulation results using PSPICE are performed to confirm the theory.