Patent ID: 7583161

Claim:
A surface acoustic wave device comprising: a piezoelectric substrate; a cover joined to the piezoelectric substrate with a support layer disposed therebetween and with a space maintained therebetween; a transmission surface acoustic wave filter and a reception surface acoustic wave filter disposed on a major surface of the piezoelectric substrate adjacent to the cover and inside the support layer; and external electrodes provided on a side of the cover opposite to a side facing the piezoelectric substrate, the external electrodes including an antenna terminal electrically connected to the transmission surface acoustic wave filter and the reception surface acoustic wave filter, a transmission input terminal electrically connected to the transmission surface acoustic wave filter, and a reception output terminal electrically connected to the reception surface acoustic wave filter; wherein the reception surface acoustic wave filter is electrically connected to the antenna terminal via an interconnection line, and the interconnection line includes a piezoelectric substrate line disposed on the piezoelectric substrate, a cover line disposed on one of an upper surface and a lower surface of the cover, and a via line that passes through the support layer and the cover so as to connect one end of the piezoelectric substrate line to one end of the cover line; the reception surface acoustic wave filter is a balanced surface acoustic wave filter including one unbalanced signal terminal to which an unbalanced signal is input and two balanced signal terminals that output balanced signals; and the antenna terminal is electrically connected to the unbalanced signal terminal, and the reception output terminal is electrically connected to the balanced signal terminals.