Patent ID: 8058923
Filing Date: 2011-11-15
Classification: G11B,G11C,H02M

Abstract:
1. A charge pump circuit charging and discharging a capacitor in response to a digital input signal, comprising: a first current source and a second current source; a first transistor and a second transistor that form a current mirror circuit; an output terminal receiving an output of the second transistor as a charging current from the current mirror circuit; and a switching circuit configured to connect the first current source to the first transistor so as to output the charging current from the current mirror circuit to the capacitor when the digital input signal is at a first level and configured to connect the second current source to the first transistor, cut the output of the second transistor by disconnecting a connection between the second transistor and the output terminal and allow a discharging current from the capacitor to the first current source when the digital input signal is at a second level, wherein the switching circuit is configured so that the discharging current flows from the output terminal to a ground through the first current source when the digital input signal is at the second level, and wherein the charge pump circuit is configured to keep the first transistor and the second transistor in an on state when the digital input signal is at the first level and at the second level.