| 摘要 |
A power supply circuit of a semiconductor memory device and a method thereof are provided to enable the operation of the semiconductor memory device regardless of the level of an external supply voltage(VDD) by changing the external supply voltage with a potential of various levels according to the external environment into an internal voltage having a level between a fixed range. A power supply voltage sensing unit(10) generates a sensing signal having an enable period above a first level and a disable period below a second level, by sensing the level of an external supply voltage(VDD). A power supply unit(20) outputs an internal voltage by driving the external supply voltage according to the enabling of the sensing signal. The second level is higher than the first level. The enabling of the sensing signal is determined whether the sensing signal exceeds a third level between the first level and the second level during an initial operation of the power supply voltage sensing unit.
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