A method of operating a memory device may include: providing a first power supply voltage to a sense amplifier during a first time interval, the first time interval being between a first time at which a voltage is provided to a first bit line, and a second time at which a pre-charge command is received; and providing a second power supply voltage to the sense amplifier during a second time interval, during which the word line is enabled after the pre-charge command is received. The second power supply voltage may be greater than the first power supply voltage.