Patent ID: 8242834

Claim:
A charge pump circuit for producing a positive charge pump voltage and a negative charge pump voltage according to an input voltage, the charge pump comprising: an input end for receiving the input voltage; a first reservoir capacitor comprising a first terminal and a second terminal, wherein the second terminal is coupled to a ground end; a second reservoir capacitor comprising a first terminal and a second terminal, wherein the second terminal is coupled to the ground end; a first output end coupled to the first terminal of the first reservoir capacitor for outputting the positive charge pump voltage; a second output end coupled to the first terminal of the second reservoir capacitor for outputting the negative charge pump voltage; and a charge pump unit coupled to the input end, the first terminal of the first reservoir capacitor, and the first terminal of the second reservoir capacitor, comprising: a first flying capacitor; a second flying capacitor; a first switch coupled between the input end and a first terminal of the first flying capacitor; a second switch coupled between the ground end and a second terminal of the first flying capacitor; a third switch coupled between the input end and the second terminal of the first flying capacitor; a fourth switch coupled between the first terminal of the first reservoir capacitor and the first terminal of the first flying capacitor; a fifth switch coupled between the ground end and the first terminal of the first flying capacitor; a sixth switch coupled between the first terminal of the second reservoir capacitor and the second terminal of the first flying capacitor; a seventh switch coupled between the input end and a first terminal of the second flying capacitor; an eighth switch coupled between the ground end and a second terminal of the second flying capacitor; an ninth switch coupled between the input end and the second terminal of the second flying capacitor; a tenth switch coupled between the first terminal of the first reservoir capacitor and the first terminal of the second flying capacitor; and a control unit for controlling on/off operation of the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, the eighth switch, the ninth switch, and the tenth switch to produce the positive charge pump voltage and the positive charge pump voltage; wherein the control unit controls the fifth switch, the sixth switch, the seventh switch and the eighth switch to be turned on and controls the first switch, the second switch, the third switch, the fourth switch, the ninth switch and the tenth switch to be turned off so that the charges stored on the first flying capacitor are transferred to the second reservoir capacitor, the negative charge pump voltage is outputted via the second output end and the input voltage charges the second flying capacitor.