Patent ID: 7034392

Claim:
A duplexer, comprising: a multilayer package substrate having a plurality of package substrates laminated on one another; a surface acoustic wave filter chip disposed on an upper surface of the package substrate corresponding to a top layer; an upper surface ground electrode formed on the upper surface of the package substrate corresponding to the top layer and connected to ground electrodes of the surface acoustic wave filter chip; a lower surface ground electrode formed on a lower surface of the package substrate corresponding to a bottom layer; ground wirings formed on at least one junction face of respective junction faces of the plurality of package substrates and connected to the upper surface ground electrode and the lower surface ground electrode via through electrodes provided in the multilayer package substrate; one or a plurality of first connecting lines provided on the side surfaces of the multilayer package substrate and connected to some or all of the ground wirings and the upper surface ground electrode and the lower surface ground electrode; and one or a plurality of second connecting lines provided on the side surfaces of the multilayer package substrate, said one or plural second connecting lines being connected to the upper surface ground electrode and the lower surface ground electrode and unconnected to the ground wirings.