VOLTAGE-CONTROLLED OSCILLATOR

PROBLEM TO BE SOLVED: To provide a voltage-controlled oscillator that is stable without causing defects such as oscillation stop and frequency hopping even when the oscillator receives a control input in excess of a variable range. SOLUTION: The voltage-controlled oscillator is configured with: a surface acoustic wave filter; matching circuits one of which is provided to a pre-stage of the surface acoustic wave filter and the other of which is provided to a post-stage of the surface acoustic wave filter; an amplifier circuit for complementing a loss of a feedback loop; a fixed phase shifter for deciding an oscillation condition and an oscillation frequency; a voltage controlled variable phase shifter for controlling the oscillation frequency by an external voltage signal; and a distributor for deciding the distribution to an external output and an in-loop output, all of oscillator components are disposed in series, and a limiting circuit is provided to a pre-stage of a control input terminal of the voltage controlled variable phase shifter. COPYRIGHT: (C)2005,JPO&NCIPI