US Patent 7265581 Level shifter

The level shifter comprises a coupling block, a PMOS switch, a first PMOS transistor and a second PMOS transistor. The coupling block receives a first signal and a second signal to generate a first control signal and a first reference voltage. The first signal and the second signal are of opposite phases. The PMOS switch is controlled by the first control signal to choose the first reference voltage or a second reference voltage to be a second control signal. The first PMOS transistor is controlled by the first control signal. The second PMOS transistor is controlled by the second control signal. The connection point between the second PMOS transistor and the first PMOS transistor outputs an output signal.