| 摘要 |
PROBLEM TO BE SOLVED: To obtain an inverting charge pump circuit capable of reducing an increase in the output voltage ripple and capable of being controlled so as not to exceed the breakdown voltage of a switch only by addition of a simple circuit without increasing the breakdown voltage of the switch. SOLUTION: In a constitution in which, after synchronization with a predetermined clock signal CLK, the charge pump circuit put into a conductive state by turning on the switches SW1 and SW2, respectively, and then it is put into a cut-off state by turning off the switches SW3 and SW4, respectively, a negative voltage is generated by repeating operations for putting a charge pump circuit into the cut-off state by turning off the switches SW3 and SW4, respectively and then putting it into the conductive state by turning off the switches SW1 and SW2, respectively. An NMOS transistor is connected between the switch SW1 and a connection CP, and a predetermined constant voltage Vb is input from a constant voltage circuit 2 into a gate of the NMOS transistor M1 so that a voltage Vcp of the connection CP is set to the constant voltage Vb or less. COPYRIGHT: (C)2009,JPO&INPIT
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