PURPOSE: To attain a wide variable width without limit due to the characteristic of a piezoelectric oscillator by providing a π type circuit, an inverting amplifier, a capacitor control means and a damping resistor to the oscillation circuit.

CONSTITUTION: A voltage controlled oscillator circuit 1 consists of a π type circuit 2, an inverting amplifier 3, and a capacitor control circuit 4. The πtype circuit 2 is formed by the series connection of a piezoelectric oscillator 5 and a damping resistor 6 both terminals of which connect respectively to ground via a load capacitor 7(8), and the inverting amplifier 3 consists of the series connection of three inverters 9a-9c and both ends are connected via a feedback resistor 10. then the oscillating frequency is controlled by varying the capacitance of the capacitors connected in T-shape across the inverter 9b with a control voltage and the variable width of the oscillating frequency is varied by varying the resistance of the damping resistor 6 connecting in series with the piezoelectric oscillator of the π type circuit 2. Thus, the voltage controlled oscillator circuit with a wide variable ratio is realized.