Patent ID: 7710193

Claim:
A high voltage generator, comprising: a detection unit for comparing a reference voltage with a high voltage and detecting a voltage level of the high voltage; an oscillator selection unit for generating a first control signal or a second control signal in response to an output signal of the detection unit and a selection signal representing a data operation mode, wherein the data operation mode is determined depending on the number of data input and output during accessing the data via word lines at once; an oscillator for generating clock signals having different frequencies in response to the first control signal or the second control signal; and a pumping unit for generating the high voltage by performing a charge pumping operation in response to the clock signals, wherein the oscillator includes: an OR gate for receiving the first control signal and the second control signal; a first NAND gate for receiving outputs of the OR gate as one input; a plurality of inverters coupled to an output terminal of the first NAND gate in series and receiving a final output coupled to the other input terminal of the first NAND gate; a plurality of metal oxide semiconductor (MOS) transistors including one terminal thereof coupled to each node of the inverters coupled in series and receiving the second control signal through a gate; and a plurality of MOS capacitors coupled between a ground voltage terminal and the other terminal of the respective MOS transistor.