High-frequency switch

A switch operating in a millimeter wave band comprising:

• a substrate;
• a signal path located on the substrate, and including a common path and two or more branch paths that branch from the common path via a branch point, each branch path partly including a transmission path having a length equivalent to one-fourth wavelength of a signal propagating through the branch path;
• a switching element shunt-connected between a grounding end and each of the branch paths, the switching element being connected to the branch path at a connection point positioned beyond the transmission path, as viewed from the branch point of the signal path, connecting and disconnecting electrically the branch path and the grounding end in response to a first control signal applied to a control electrode of the switching element;
• a matching circuit connected to the branch path beyond the connection point for the switching element, as viewed from the branch point of the signal path, and including a stub shunt-connected to the branch path;
• and
• a matching semiconductor element connected between the stub of the matching circuit and the grounding end, the matching semiconductor element connecting and disconnecting the stub and the grounding end in response to a second control signal applied to a control electrode of the matching semiconductor element in accordance with the connection or disconnection of the branch path and the grounding end by the switching element.