| 摘要 |
PROBLEM TO BE SOLVED: To perform charge operation normally, by preventing a parasitic diode from being biased reversely in a charge pump circuit which performs boosting with a small step of Vdd or under in power supply voltage. SOLUTION: This charge pump circuit is provided with a means for biasing the substrate potential of a MOS transistor M2 for control so that a forward current may not flow substantially to a parasitic diode DP1 throughout the all process of charge operation. Specifically, the substrate of the MOS transistor M2 for control is biased with the voltage of a junction between the MOS transistor M2 for control and a capacitor 1, in case that the MOS transistor M2 for control is of p-channel type.
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