Patent ID: 8593068

Claim:
A two-wire AC switch connected between an AC power supply and a load, said two-wire AC switch comprising: a bidirectional switch element connected in series with the AC power supply and the load to form a closed-loop circuit, said bidirectional switch element causing passing current to flow bi-directionally and selecting whether to flow or block the passing current, wherein said bidirectional switch element includes: a substrate; a semiconductor multilayer structure formed above said substrate, said semiconductor multilayer structure including a group-III nitride semiconductor; a first ohmic electrode and a second ohmic electrode which are formed above said semiconductor multilayer structure, said first ohmic electrode being electrically connected to one of the AC power supply and the load, and said second ohmic electrode being electrically connected to the other one of the AC power supply and the load; and a first gate electrode and a second gate electrode which are formed above said semiconductor multilayer structure and between said first ohmic electrode and said second ohmic electrode, said first gate electrode being provided closer to said first ohmic electrode than to said second ohmic electrode, and said second gate electrode being provided closer to said second ohmic electrode than to said first ohmic electrode; a full-wave rectifier connected between said first ohmic electrode and said second ohmic electrode to perform full-wave rectification on AC power supplied from the AC power supply, the AC power supply being included in the closed-loop circuit that includes the AC power supply, the load and the bidirectional switch element; a power supply circuit which smoothes a voltage provided after the full-wave rectification by said full-wave rectifier to generate DC power; a drive circuit which receives the DC power from said power supply circuit, and outputs a first control signal to said first gate electrode and a second control signal to said second gate electrode; and a control circuit which receives the DC power from said power supply circuit, and controls said drive circuit to output the first control signal to said first gate electrode and the second control signal to said second gate electrode so as to turn said bidirectional switch element ON, so that the AC power supply supplies power to the load, the first control signal having a voltage higher than a threshold voltage of said first gate electrode, and the second control signal having a voltage higher than a threshold voltage of said second gate electrode, and the AC power supplied from the AC power supply is provided to said bidirectional switch element without being converted to DC power.