| 摘要 |
PROBLEM TO BE SOLVED: To provide a pulse width modulation circuit in which the output frequency or the minimum pulse width is kept constant even at the time of pulse width modulation. SOLUTION: The pulse width modulation circuit comprises means for generating a pulse depending on the ratio of first and second currents, a current source means generating a current equal to the sum of the first and second currents, a modulation signal generating means for modulating the duty ratio of a pulse by generating a modulation signal and varying the ratio of first and second currents, and a power supply control means for controlling the output frequency by controlling the current of the current source means.
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