| 摘要 |
PROBLEM TO BE SOLVED: To provide a charge pump circuit capable of improving efficiency by suppressing operation of a parasitic transistor. SOLUTION: In the charge pump circuit, the potential of a P-type semiconductor substrate 20 can be a ground potential (GND) of low impedance by separating a back gate of N channel MOS transistors Q12-Q16 from the P-type semiconductor substrate 20. The MOS transistors Q15 and Q16 acting as a selecting switch of the back gate of the N channel MOS transistor Q14 is provided to output a voltage of which polarity of power supply voltage Vin is inverted to an output terminal Pout. Thereby, a potential difference between N type semiconductor and P-type semiconductor adjoining the transistor Q14 comes to be a diode forward drop voltage or lower, thereby suppressing operation of a parasitic NPN transistor that causes degradation of efficiency. COPYRIGHT: (C)2009,JPO&INPIT
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