Acoustic wave devices that you have to suppress the higher-order transverse mode wave

摘要

In an acoustic wave device, a high-order transverse mode wave which is an unnecessary wave is suppressed. The acoustic wave device includes: a piezoelectric substrate; at least one pair of IDT electrodes formed on the piezoelectric substrate; and a dielectric film which covers at least a part of the piezoelectric substrate and the IDT electrodes, and the IDT electrodes each has a plurality of electrode fingers. The dielectric film covers at least an area in which the electrode fingers are arranged interleaved with each other. An acoustic velocity of an acoustic wave in an intersection area, within the region, which is a portion from ends of the electrode fingers to a predetermined length or more inward from the ends, is greater than an acoustic velocity of an acoustic wave in an edge area including end portions of the electrode fingers.