Patent ID: 8917112

Claim:
A bidirectional level shifter, comprising: a first signal terminal; a second signal terminal; a first switch, coupled between the first signal terminal and a ground level, for controlling a conduction status between the first signal terminal and the ground level; an inverter, for receiving a signal from the first signal terminal through a first common node, and transmitting a control signal according to the received signal; a Schottky diode, including an anode and a cathode, the anode receiving a signal from the second signal terminal through a second common node; a second switch, coupled between the cathode of the Schottky diode and the ground level, for controlling a conduction status between the cathode of the Schottky diode and the ground level according to the control signal; a comparing circuit, including an input terminal coupled to a reference voltage and another input terminal coupled to the second signal terminal through the second common node, for controlling the first switch according to a comparing result between the two input terminals, wherein the reference voltage is lower than a forward bias voltage of the Schottky diode; a first voltage source, coupled to the first common node, for raising a voltage at the first common node when the voltage at the first common node is not controlled by any other part of the bidirectional level shifter; and a second voltage source, coupled to the second common node, for raising a voltage at the second common node when the voltage at the second common node is not controlled by any other part of the bidirectional level shifter.