Patent ID: 7042313

Claim:
A surface acoustic wave device comprising: a piezoelectnc substrate; two surface acoustic wave fitters, each of said two surface acoustic wave filters including three comb-shaped electrode portions arranged along the propagation direction of surface acoustic waves on the piezoelectric substrate, a middle one of the three comb-shaped electrode portions is connected to an unbalanced terminal and the left and right comb-shaped electrode portions are connected to balanced terminals so as to provide a balanced to unbalanced conversion function; wherein at least one electrode finger of outermost electrode fingers in each of said three comb-shaped electrode portions of at least one of said two surface acoustic wave filters is connected to one of said unbalanced terminal and said balanced terminals; the phase of said two surface acoustic wave filters is 180 degrees offset from each other; the phase of the left and right comb-shaped electrode portions of one of said two surface acoustic wave filters is 180 degrees offset from each other; the two surface acoustic wave filters are longitudinally coupled resonator type surface acoustic wave filters; and in one of the two surface acoustic wave filters, at least one electrode finger of outermost electrode fingers in one of said three comb-shaped electrode portions is connected to ground.