| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillating circuit in which an oscillator is provided, with early oscillation start time, and the non-deformed waveform of signal. SOLUTION: The oscillating circuit has a resonator, such as an SAW resonator; a differential amplifier for amplifying signal, such as a high-frequency signal generated in the resonator, and outputting a feedback signal to the resonator; and a means for changing a gain of the differential amplifier in a predetermined time, from power-on and in a time point after elapse of the predetermined time. As a means for changing a gain, a gain adjusting circuit is provided on the differential amplifier, with a first transistor 13 connected to a constant voltage source and a second transistor 14 connected, by changing a switch 15 to the constant voltage source or a second power source. Since connection/disconnection of the switch 15 can shorten the time required for starting the oscillation with stable amplitude, and the gain of the circuit can be suppressed after stable oscillation, the oscillating circuit can be realized in which the waveform of the signal is not deformed. COPYRIGHT: (C)2008,JPO&INPIT
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