Patent ID: 7038394

Claim:
A ramp voltage generating apparatus comprising: a voltage output circuit for outputting a ramp voltage; a ramp voltage generating circuit for generating a plurality of ramp voltages out of phase with each other from the ramp voltage; and a control circuit for controlling an operation of the ramp voltage generating circuit, wherein the ramp voltage generating circuit includes a plurality of voltage generating circuit portions connected in parallel to a voltage input terminal to be supplied with the ramp voltage output from the voltage output circuit, each of the voltage generating circuit portions includes: a voltage output terminal; a capacitor arranged on a line extending from the voltage input terminal to the voltage output terminal; an amplifier arranged on the portion of the line closer to the voltage output terminal than to the capacitor; a first switching element interposed between the capacitor and the amplifier on the line; a second switching element arranged on a feedback line connecting a output terminal of the amplifier and a connecting point of the capacitor and the first switching element; and a third switching element arranged on a power supply line connected to the connecting point, the control circuit turns on the third switching elements of the plurality of voltage generating circuit portions while shifting the time point of switching each of the third switching elements from off to on state, and the control circuit turns off the first switching elements and, also, turns on the second switching elements of the plurality of voltage generating circuit portions during the period including the fall time point and the rise time point of the ramp voltage input to the voltage input terminal.