Patent ID: 7208995

Claim:
An amplifier that amplifies an input signal using an output voltage obtained by a charge pump circuit, wherein the charge pump circuit comprises: a first switch that selects one of a high voltage power supply and a low voltage power supply; a capacitor having a first terminal connected to the first switch and which is charged and discharged; and a second switch that selectively connects a second terminal of the capacitor either to the low voltage power supply or an output terminal, wherein the second terminal of the capacitor is connected to the low voltage power supply by the second switch while the high voltage power supply is selected by the first switch and the second terminal of the capacitor is connected to the output terminal by the second switch while the low voltage power supply is selected by the first switch so that an output voltage which is lower than the voltage of the low voltage power supply by a voltage corresponding to the voltage of the high voltage power supply is obtained at the output terminal, and a first constant current source that supplies charge to the capacitor for charging the capacitor with a first constant current and a second constant current source that draws charge from the capacitor for discharging the capacitor with a second constant current, the low voltage power supply is ground, a voltage that is lower than ground is obtained as an output voltage, an amplified signal that varies with the voltage of the low voltage power supply as a center voltage is obtained at an output of the amplifier, the input signal is a video signal containing a synchronizing signal, and the first switch and the second switch are controlled based on the synchronizing signal separated from the video signal.