Patent ID: 7595680

Claim:
A bidirectional switch for controlling between a conduction state in which a current flows at least in one direction between a first terminal and a second terminal and a cut-off state in which a current does not flow therebetween, the switch comprising: a field-effect transistor including a first ohmic electrode and a second ohmic electrode of which one serves as a source electrode and the other serves as a drain electrode and a gate electrode formed between the first ohmic electrode and the second ohmic electrode, the first ohmic electrode being connected to the first terminal, the second ohmic electrode being connected to the second terminal; and a control circuit for applying a bias voltage to the gate electrode to control between the conduction state and the cut-off state, wherein the control circuit applies the bias voltage with reference to the first ohmic electrode when a potential of the second ohmic electrode is higher than the potential of the first ohmic electrode and applies the bias voltage with reference to the second ohmic electrode when the potential of the second ohmic electrode is lower than the potential of the first ohmic electrode.