SUPPLY VOLTAGE GENERATING CIRCUIT
First Claim
1. A method for generating a supply voltage, comprising:
- selecting one of a first input node supplied with a first power supply voltage and a second input nodes supplied with a second power supply voltage that is different from the first power supply voltage,coupling a selected one of the first and second input nodes to an output node so that a boosted voltage at an output terminal takes a first level when the first input node is coupled to the output node and a second level when the second input node is coupled to the output node,wherein the boosted voltage, which is greater than a voltage at the selected one of the first and second input nodes, is generated by a voltage booster circuit including first and second transistors and a capacitor, the first transistor being provided between the input terminal and one end of the capacitor, the second transistor being provided between the one end of the capacitor and the output terminal.
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Accused Products
Abstract
A supply voltage generating circuit that enables a reduction in chip area includes: a booster for outputting a boosted voltage upon generating the boosted voltage by charge pumping of a capacitor element; a power-supply step-down unit for stepping down voltage of an external power supply to a voltage within a breakdown-voltage range of the capacitor element, and applying the stepped-down voltage to the power supply of the booster; and a switch element for switching between application of the external power supply to the power supply of the booster directly or via the power-supply step-down unit. The booster comprises multiple stages of booster circuits. The thicknesses of gate oxide films of capacitor elements constituted by MOS transistors included in respective ones of the booster circuits are the same and are made smaller than the thickness of a gate oxide film of a MOS transistor included in a load circuit having the output of the booster at its power supply.
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Citations
10 Claims
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1. A method for generating a supply voltage, comprising:
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selecting one of a first input node supplied with a first power supply voltage and a second input nodes supplied with a second power supply voltage that is different from the first power supply voltage, coupling a selected one of the first and second input nodes to an output node so that a boosted voltage at an output terminal takes a first level when the first input node is coupled to the output node and a second level when the second input node is coupled to the output node, wherein the boosted voltage, which is greater than a voltage at the selected one of the first and second input nodes, is generated by a voltage booster circuit including first and second transistors and a capacitor, the first transistor being provided between the input terminal and one end of the capacitor, the second transistor being provided between the one end of the capacitor and the output terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification