Abstract: A power supply circuit for driving a capacitive load includes a driving pulse generation circuit that generates a driving pulse of a specified frequency, a single drive circuit that is controlled by this driving pulse, and an autotransformer, where a center tap is connected to a source voltage, and forms a resonant circuit by using an autotransformer and a capacitive load, which is connected thereto. Alternatively, instead of driving pulse generation circuit, it includes a differential amplifier and a positive feedback path that performs positive feedback from one of the terminals of the autotransformer to the input terminal of the differential amplifier. In this manner, by driving the autotransformer using the single drive circuit, the entire autotransformer can be utilized in an efficient manner and a smaller and cheaper power supply circuit can be realized.

Abstract: A power terminal is connected to a DC power source. A differential amplifier has primary and secondary input terminals and an output terminal, and a device applies a reference voltage to the secondary input terminal of the differential amplifier. A phase inverter has an input terminal connected to the output terminal of the differential amplifier and has primary and secondary output terminals that output two output signals of opposite phase. A push-pull drive circuit has primary and secondary input terminals connected to the primary and secondary output terminals of the phase inverter, and has primary and secondary output terminals connected to a switching element that alternately turns on and off by being driven by the two output signals of opposite phase that are provided from the output terminals of the phase inverter.

Abstract: A power terminal is connected to a DC power source. A differential amplifier has primary and secondary input terminals and an output terminal, and a device applies a reference voltage to the secondary input terminal of the differential amplifier. A phase inverter has an input terminal connected to the output terminal of the differential amplifier and has primary and secondary output terminals that output two output signals of opposite phase. A push-pull drive circuit has primary and secondary input terminals connected to the primary and secondary output terminals of the phase inverter, and has primary and secondary output terminals connected to a switching element that alternately turns on and off by being driven by the two output signals of opposite phase that are provided from the output terminals of the phase inverter.