US Patent 7567469 Over driving pulse generator

A semiconductor memory device controls an over driving period according to fluctuation of a supply voltage VDD. The semiconductor memory device includes a bit line sense amplifier, a sense amplifying driver and an over driving controller. The over driving controller includes a delay unit for delaying an input signal, a supply voltage detector for detecting the level of the supply voltage VDD, a delaying controller for controlling a delay time of the delay unit in response to an output of the supply voltage detector, and an output unit for outputting a over driving pulse, whose width is controlled according to the fluctuation of the supply voltage VDD, by performing a logic operation to the input signal and an output of the delay unit.