Patent ID: 8922270

Claim:
A charge pump for an integrated circuit (IC), the IC including an internal capacitor that has first and second terminals, the first terminal being biased to a first fixed reference voltage level, comprising: an output terminal configured to be coupled to the second terminal of the internal capacitor of the IC; an external capacitor, configured to be disposed outside the IC; and a switch module coupled to the external capacitor and configured to be coupled to the internal capacitor, and configured to control the external capacitor and the internal capacitor to charge and discharge in turn, the switch module comprising: a first switch set configured to be coupled between a plurality of input voltages including first and second input voltages and the external capacitor, the first switch set comprising: a first switch configured to be coupled between the first input voltage and the external capacitor; and a second switch configured to be coupled between the second input voltage and the external capacitor; and a second switch set configured to be coupled between the internal capacitor and the external capacitor; the second switch set comprising: a third switch coupled between the output terminal and the external capacitor; and a fourth switch configured to be coupled between a third input voltage, set at a second fixed reference voltage level different from the first fixed reference voltage level, and the external capacitor; wherein the switch module is configured to control the external capacitor in a first operating period to charge without providing current to the output terminal, and to control the internal capacitor in said first operating period to discharge to the output terminal.