Patent ID: 8198869

Claim:
A method of charging a capacitive device having first and second capacitive elements connected in series, using a charging circuit having a third capacitive element, and first and second switching circuits, the method comprising the steps of: providing a first clock signal to control switching of the first switching circuit, and providing a second clock signal out of phase with respect to the first clock signal to control switching of the second switching circuit, the third capacitive element being charged from an input when the first switching circuit is in a first switching state and the second switching circuit is in a second switching state, the first capacitive element being charged from a charge at the third capacitive element, and the second capacitive element being charged from the input when the first switching circuit is in the second switching state and the second switching circuit is in the first switching state, and determining a relationship between first voltage at the first capacitive element and second voltage at the second capacitive element to modify the duty cycle of the first clock signal in accordance with the relationship.