| 摘要 |
<p>PURPOSE: To remove beat noise which is produced by the asynchronization of the reference clock of an external circuit and noise which cannot be removed by a smoothing circuit by synchronizing the oscillation of an oscillator with the reference clock signal of the external circuit. CONSTITUTION: When the outputs of first and second comparators are respectively given as the set and reset inputs of a flip flop, the outputs are given to a charging/discharging circuit and a triangular wave voltage is obtained at a connecting point C. When the reference voltage switching timing of such a reference voltage switching circuit is synchronized with a frequency dividing clock A, the oscillating period of the voltage C is also synchronized to the clock A. Therefore, the switching of switching transistors 54a and 54b which operate in response to the output of a triangular wave oscillation circuit are also synchronized with the clock A and the beat noise which is produced by the asynchronization of the reference clock and noise which cannot be removed by smoothing circuits 55a and 55b can be removed.</p> |
