A semiconductor memory device includes at least one sense amplifier, a controller and a sense amplifier driver. The sense amplifier includes a PMOS sense amplifier and an NMOS sense amplifier configured to be respectively activated in response to a first supply voltage and a second supply voltage, and to sense and amplify a voltage difference between a corresponding bit line pair. The controller is configured to set an operating mode in response to an external command, to control activation timing of a PMOS drive activation signal and an NMOS drive activation signal according to the set operating mode, and to output the PMOS drive activation signal and the NMOS drive activation signal. The sense amplifier driver is configured to apply the first and second supply voltages to the PMOS and NMOS sense amplifiers, respectively, in response to the PMOS drive activation signal and the NMOS drive activation signal.