Patent ID: 6933794
Filing Date: 2005-08-23
Classification: H03B

Abstract:
1. A voltage-controlled oscillator comprising: a voltage-controlled phase-shift circuit for outputting an output signal in which the phase of an input signal is shifted by a predetermined amount in accordance with an external control voltage; a plurality of SAW resonators, each of which resonates at a predetermined resonance frequency; first switching means for selecting one of said plurality of SAW resonators in accordance with the external control voltage; frequency selection means for selecting an output signal having a predetermined resonance frequency from one SAW resonator among said plurality of SAW resonators, which is selected by said first switching means; an oscillation differential amplifier for amplifying and outputting a resonance signal of said predetermined resonance frequency; and a feedback-buffer differential amplifier for inputting the output signal from said oscillation differential amplifier, wherein said voltage-controlled phase-shift circuit, the SAW resonator selected by said first switching means, said frequency selection means, said oscillation differential amplifier, and said feedback-buffer differential amplifier form a positive-feedback oscillation loop.