Patent ID: 7944329

Claim:
An acoustic wave filter device including an unbalanced terminal and first and second balanced terminals and having a balance-unbalance conversion function, the acoustic wave filter device comprising: a piezoelectric substrate; a longitudinally coupled resonator-type acoustic wave filter unit including at least three IDTs, the longitudinally coupled resonator-type acoustic wave filter unit being provided on the piezoelectric substrate and being connected between the unbalanced terminal and the first and second balanced terminals; a first ground wiring provided on the piezoelectric substrate and including a first end portion and a second end portion, the first end portion of the first ground wiring being connected to a ground-side end portion of an IDT connected to the first or second balanced terminal among the at least three IDTs; a second ground wiring provided on the piezoelectric substrate and including a first end portion and a second end portion, the first end portion of the second ground wiring being connected to a ground-side end portion of an IDT connected to the unbalanced terminal; and first and second grounding electrode pads provided on the piezoelectric substrate, the second end portions of the first and second ground wirings being electrically connected to the first and second grounding electrode pads, respectively; wherein the second ground wiring is arranged to branch to first and second branched wiring portions in a middle portion from the first end portion toward the second end portion, and the first and second branched wiring portions are arranged so as to sandwich an area in which the at least three IDTs are provided.