Patent ID: 8089329

Claim:
A semiconductor switch including a first input/output terminal, a second input/output terminal, a third input/output terminal, wherein, the first input/output terminal and the second input/output terminal are connected by a first route, and the first input/output terminal and the third input/output terminal are connected by a second route; a first transistor having a source electrode, a gate electrode, and a drain electrode, connected between the first input/output terminal and the second input/output terminal; a first transmission line having a length and connected between the first input/output terminal and the third input/output terminal; a second transmission line arranged parallel to the first transmission line, for branching a part of a high frequency signal passing through the first transmission line by coupling; and a detector circuit connected to an end of the second transmission line, for outputting a DC voltage corresponding to power level of the high frequency signal branched by the second transmission line, wherein the first transistor is controlled and switched according to an output from the detector circuit to switch between the first route and the second route.