| 摘要 |
In a voltage controlled oscillator including an amplifier, a feedback circuit and a crystal oscillator, two MOS transistors M 1 , M 2 are connected for use as variable capacity elements for the frequency adjustment of the voltage controlled oscillator. Drains of the MOS transistors M 1 , M 2 are respectively connected to an XT terminal and an XTB terminal of the crystal oscillator. Sources of the MOS transistors M 1 , M 2 are made common and connected to a grounding terminal via a capacitor C 3 . Gates of the MOS transistors M 1 , M 2 are made common, and an added voltage signal of a temperature compensating signal voltage and an external frequency control signal voltage is applied to the common gate terminals of the MOS transistors to thereby perform the frequency control of the oscillator.
|
