| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage-controlled crystal oscillator in an oscillation circuit utilizing an ON resistance of a transistor wherein a frequency variable width is greatly extended. SOLUTION: The voltage-controlled crystal oscillator 5 comprises: the oscillation circuit such as a Colpitts oscillation circuit; a crystal vibrator 3 connected to the oscillation circuit 2; and a variable capacitance circuit 6 whose capacitance varies with an external control voltage applied externally, capacitors C1, C2 are connected in series between the crystal vibrator 3 and ground in the variable capacitance circuit 6, and transistors TR1, TR2 are connected to the capacitor C2 in a way that the drains of the transistors TR1, TR2 are connected to the capacitor C3 and the sources of the transistors TR1, TR2 are connected to ground. Moreover, an externally applied external control voltage is applied to the gates of the transistors TR1, TR2 via a resistor R1. COPYRIGHT: (C)2006,JPO&NCIPI
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