| 摘要 |
PROBLEM TO BE SOLVED: To provide a voltage controlled oscillator for achieving low phase noise while guaranteeing the start and maintenance of stable oscillation even under the condition of low power supply voltage. SOLUTION: In the voltage controlled oscillator including an LC parallel resonance circuit in which an impedance changes in accordance with a control input voltage, and a negative resistance circuit for introducing negative resistance to the LC parallel resonance circuit, the negative resistance circuit is provided in parallel with the LC parallel resonance circuit, and at least a first amplifier circuit which includes a first transistor pair subjected to cross coupling through a capacitor to perform a class C amplification operation when the gate of each transistor of the first transistor pair is biased by first bias voltage, and a second amplifier circuit which includes a similar circuit configuration to perform a Class C amplification operation when the gate of each transistor is biased by second bias voltage different from the first bias voltage are included. COPYRIGHT: (C)2011,JPO&INPIT
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