| 摘要 |
Oscillation in which unwanted vibration (B mode) is surely suppressed while stable oscillation by principal vibration (C mode) is obtained is obtained. In a Colpitts oscillator including a piezoelectric vibrator, a transistor, and a first and second divided capacitive components, by inserting a feedback circuit formed by connecting a third capacitive component and a first inductor in series between a connection midpoint between the first capacitive component and the second capacitive component and an emitter of the transistor, inserting a second inductor in parallel with the second capacitive component, and setting the parallel resonance frequency of the second capacitive component and the second inductor in the vicinity of the oscillation frequency of the oscillator, the frequency band in which the negative resistance of the circuit side seen from the piezoelectric vibrator appears is set to a narrow band containing only a desired frequency to suppress unwanted vibration of the oscillator.
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