Power circuit for driving a capacitive load

A power circuit comprising:

• a differential amplification/phase inverting circuit having first and second inputs, the first input being connected to a first voltage, said differential amplification/phase inverting circuit having first and second periodic outputs having first and second phases;
• a push-pull drive circuit having first and second inputs connected to the first and second outputs of the differential amplification/phase inverting circuit and having first and second outputs;
• a positive feedback path connecting the first output of said push-pull drive circuit to the first input of said differential amplification/phase inverting circuit;
• and
• an autotransformer having first and second ends connected to the first and second outputs of said push-pull drive circuit, said autotransformer having a tap connected to a source of a second voltage higher than the first voltage, the first and second ends being connectable to a capacitive load such that a periodic waveform is applied to the load.

A power circuit comprising:

• a power terminal connected to a DC power source;
• a differential amplifier that has primary and secondary input terminals and an output terminal;
• a device that applies a reference voltage to the secondary input terminal of said differential amplifier;
• a signal generator that has an input terminal connected to the output terminal of said differential amplifier and primary and secondary output terminals that output two output signals of opposite phase;
• a push-pull drive circuit that has primary and secondary input terminals connected to the primary and secondary output terminals of said signal generator, a switching element that alternately turns on and off by being driven by the two output signals of opposite phase provided from the output terminals of the signal generator, and primary and secondary output terminals that are connected to the switching element;
• an autotransformer with a tap that is connected to said power terminal and first and second terminals at both sides of the tap, the first and second terminals being connected to the primary and secondary output terminals at said push-pull drive circuit, respectively, in order for a capacitive load to be connected at both sides and such that a sinusoidal AC voltage is applied to the load;
• and
• a positive feedback path that connects one terminal of said autotransformer to one of the input terminals of said differential amplifier.