VOLTAGE CONTROLLED OSCILLATION CIRCUIT

摘要

A VCO circuit (2) includes a temperature detecting circuit (4), a voltage generating circuit (5), a switch (SW3), a resonance circuit and an oscillator (6). The temperature detecting circuit (4) detects temperature, and the voltage generating circuit (5) generates and outputs a voltage for rough adjustment corresponding to the detected temperature. The switch (SW3) selects either a DC voltage for fine adjustment or a voltage for the rough adjustment. The resonance circuit includes a variable capacitance diode (CV) having a capacitance value adjusted based on the voltage selected by the switch (SW3), capacitors (C2, C3), and an inductor (L1), and has a prescribed resonance frequency. The oscillator (6) generates and outputs an oscillation signal having an oscillation frequency (f<SUB>OSC</SUB>) corresponding to the resonance frequency by using the resonance circuit.