| 摘要 |
PURPOSE: A positive charge pump circuit for a flash memory device is provided to output a constant pumping voltage in the wide range of a supply voltage by selecting one of a plurality of pumping capacitors, each having different capacity, according the voltage level of the input supply voltage. CONSTITUTION: The positive charge pump circuit includes a voltage detector(11), reference voltage generator(12), a comparator(13), a multiplexer(14), a capacitor selector and a positive charge pumping portion(16). The voltage detector determines a voltage level to be pumped in response to a charge pump enable signal(EN). The reference voltage generator generates a reference voltage in response to the charge pump enable signal. The comparator compares the output voltage of the voltage detector with the reference voltage in response to the charge pump enable signal and generates a plurality of comparison signals. The multiplexer receives the comparison signals and generates a plurality of pumping capacitor selection signals. The capacitor selector selects one of a plurality of pumping capacitors, each having different capacity in response to the charge pump enable signal, clock signals generates by a clock generator(15), and the pumping capacitor selection signals. The positive charge pumping portion pumps the supply voltage by the pumping capacitor selected by the capacitor selector.
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