Patent ID: 7116156

Claim:
A charge pump circuit comprising: a plurality of charge transfer transistors connected in series; a plurality of capacitors each having one end connected to a corresponding connecting point of the charge transfer transistors; a first clock driver for supplying clock pulses to the other end of the capacitor; a second clock driver for supplying clock pulses to the other end of the capacitor and having higher driving capacity than the first clock driver; and a clock driver control circuit for initiating operation of the first clock driver when the charge pump circuit starts operating and initiating operation of the second clock driver after a predetermined elapsed time, wherein the clock driver control circuit stops operation of the first clock driver at an end of the predetermined elapsed time, wherein an output voltage is obtained from one of the plurality of charge transfer transistors and further wherein the clock driver control circuit comprises a comparator which compares a voltage corresponding to the output voltage with a predetermined reference voltage and a control circuit which controls the first clock driver and the second clock driver according to an output signal of the comparator.