A level shifter comprises a first control switch (207) for connecting an output terminal to a first supply voltage (VDDH) to set an output signal to be high, and a second control switch (208) for connecting the output terminal to a signal ground (GND) to set the output signal to be low. The level shifter comprises a pre-charging switch (210) for connecting the output terminal to the first supply voltage, and an input gate circuit (211) for controlling an ability of an input signal to control the second control switch. The level shifter comprises a keeper circuit (212) for controlling the first control switch based on the output signal. The first control switch is controlled with the first supply voltage when the output signal is low, and with a second supply voltage that is between the first supply voltage and the signal ground when the output signal is high.