Patent ID: 8013692

Claim:
A boundary acoustic wave device, comprising: a piezoelectric substrate; a first dielectric layer provided on the piezoelectric substrate; and an electrode structure provided at an interface between the piezoelectric substrate and the first dielectric layer; wherein the electrode structure includes: a plurality of series arm resonators connected to one another in series on a series arm that connects an input terminal and an output terminal; a parallel arm resonator connected between the series arm and a ground potential on each of a plurality of parallel arms provided between the series arm and the ground potential; a plurality of ground wiring lines respectively connected to ends of the plurality of the parallel arms to be connected to the ground potential; and a plurality of ground pads respectively connected to the plurality of the ground wiring lines; wherein the electrode structure defines a ladder filter; the boundary acoustic wave device further comprises: a signal wiring line defining the series arm arranged so as to be located between at least two of the plurality of the ground pads; and a ground connection conductor arranged to electrically connect the at least two of the plurality of ground pads; the signal wiring line is arranged to three-dimensionally cross the ground connection conductor with the first dielectric layer therebetween; and all of the plurality of ground pads are electrically connected to one another.