Acoustic wave device, multiplexer, and communication apparatus

Abstract

An acoustic wave device includes a substrate 3, a multilayer film 5 on the substrate 3, an LT layer 7 which is located on the multilayer film and is configured by a single crystal of LiTaO3, and an IDT electrode 19 on the LT layer 7. In the multilayer film 7, a differential value D obtained by subtracting a total value of values each obtained by multiplying a density and thickness of a film having a slower acoustic velocity than a transverse wave acoustic velocity of the LT layer 7 from a total value of values each obtained by multiplying a density and thickness of a film having a faster acoustic velocity than the transverse wave acoustic velocity of the LT layer 7 is negative, and a thickness of the LT layer 7 is less than 2 p where a pitch of electrode fingers in the IDT electrode 19 is “p”.

Dependencies are inferred from the claim text.