A level shifter including a first boost circuit, an inverter, a second boost circuit and a level shift circuit is disclosed. The first boost circuit receives an input signal, and a first amplification factor for the input signal is determined based on a control signal. The inverter receives the input signal to generate an inverted input signal. The second boost circuit is coupled to an output terminal of the inverter to receive the inverted input signal, and a second amplification factor for the inverted input signal is determined based on the control signal. The level shift circuit has a first input terminal and a second input terminal respectively coupled to output terminals of the first boost circuit and second boost circuit to change the voltage level of output signals from the first boost circuit and second boost circuit to a first voltage level.