SURFACE ACOUSTIC WAVE DEVICE

PURPOSE:To suppress bulk acoustic wave resonance by providing strip shape slots to the rear side opposite to the output electrode of a piezoelectric substrate and specifying the depth, width and pitch of the slots to distribute the in-phase component and the reverse phase component of a reflected wave on the rear side nearly equal. CONSTITUTION:A couple of comb-shaped electrodes 2, 2' converting an electric signal into a surface acoustic wave are formed to one major side of a piezoelectric substrate 1, and an output electrode 3 is formed to a position clipped by the couple of comb-shaped electrodes. Then strip shape slots 6 whose depth is (d), whose width p1 and whose pitch is p2 are provided onto other side of the piezoelectric substrate 1 at least opposite to the output electrode 3 in a way of nearly satisfying the relations of d=vb/4.f0 and p1=p2. Thus, the in- phase component and the reverse phase component of a reflected wave on the rear side are almost equally distributed, then bulk acoustic wave resonance caused between the output gate electrode and the rear side of the substrate is suppressed and the frequency characteristic and the spurious characteristic are improved.