| 摘要 |
An acoustic wave device (5) includes a piezoelectric substrate (6) made of a lithium niobate material having the Euler angles (&phgr;, &thetas;, ψ), an electrode (7) disposed on the piezoelectric substrate (6) for exciting a major acoustic wave of a wavelength λ, and a protective layer (8) disposed on the piezoelectric substrate (6) to cover the electrode (7). The protective layer (8) has a thickness greater than 0.27λ. The Euler angles satisfy −100°≦̸&thetas;≦̸−60°; 1.193&phgr;−2°≦̸ψ≦̸1.193&phgr;+2°; and either ψ≦̸−2&phgr;−3° or −2&phgr;+3°≦̸ψ. |
