Patent ID: 6707703
Filing Date: 2004-03-16
Classification: G11C,H02M

Abstract:
A negative voltage generating circuit comprising:a first capacitor having first and second electrodes facing each other, the first electrode being connected to an output node; a first switching element connected between the output node and a first power supply voltage; a first switching circuit having an output connected through a first node to the second electrode, the first switching circuit selectively coupling the output to one of the first power supply voltage and a second power supply voltage higher than the first power supply voltage, or putting the output into a high impedance state; a second capacitor having first and second electrodes facing each other, the first electrode being connected to the first node; a second switching circuit having an output connected through a second node to the second electrode of the second capacitor, the second switching circuit selectively coupling the output thereof to one of the first power supply voltage and a third power supply voltage higher than the first power supply voltage, or putting the output thereof into a high impedance state; and a control circuit controlling the first switching element, the first switching circuit, and the second switching circuit so that: (1) in a first step, the first switching element is turned on, and the outputs of the first and second switching circuits are coupled to the second power supply voltage and the first power supply voltage, respectively; (2) in a second step, the output of the second switching circuit is coupled to the third power supply voltage with the output of the first switching circuit being put in the high impedance state; and (3) in a third step, the output of the first switching circuit is coupled to the first power supply voltage with the first switching element being off and the output of the second switching circuit being put in the high impedance state.