| 摘要 |
PROBLEM TO BE SOLVED: To provide an oscillation circuit for obtaining an output signal having a stable vibration waveform even immediately after start up. SOLUTION: An oscillation circuit 1A includes: a main oscillation circuit 2A for outputting a vibration output voltage having a vibration waveform based on an input voltage; a phase comparator 3 that receives an output signal corresponding to a vibration output voltage of the main oscillation circuit 2A and a clock synchronizing signal SYNC having a predetermined frequency, and outputs a voltage corresponding to a phase difference between the output signal and the clock synchronizing signal SYNC; a first low-pass filter 4 for smoothing the output voltage of the phase comparator 3; and a switching circuit 5A which inputs the output voltage of the first low-pass filter 4 to the main oscillation circuit 2A when the output voltage of the first low-pass filter 4 is equal to or higher than a reference voltage Vref1, and which inputs the reference voltage Vref1 to the main oscillation circuit 2A when the output voltage of the first low-pass filter 4 is lower than the reference voltage Vref1. COPYRIGHT: (C)2011,JPO&INPIT
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