A level shifter includes one PMOS and two NMOS transistors. A source of the first NMOS transistor is coupled to a low power supply voltage. An input signal is coupled to a gate of the first NMOS transistor and a source of the second NMOS transistor. The input signal has a voltage level up to a first power supply voltage. A source of the PMOS transistor is coupled to a second power supply voltage, higher than the first power supply voltage. An output signal is coupled between the PMOS and the first NMOS transistors. The first NMOS transistor is arranged to pull down the output signal when the input signal is a logical 1, and the second NMOS transistor is arranged to enable the PMOS transistor to pull up the output signal to a logical 1 at the second power supply voltage when the input signal is a logical 0.