Patent ID: 6137207
Filing Date: 2000-10-24
Classification: H03H

Abstract:
A surface acoustic wave device comprising an inter-digital electrode on a surface of a substrate, wherein:said substrate is made up of a langasite single crystal having the formula, La.sub.3 Ga.sub.5 SiO.sub.14, and belonging to a point group 32,when a cut angle of said substrate cut out of the langasite single crystal and a direction of propagation of surface acoustic waves on said substrate are represented in terms of Euler's angles (.phi., .theta., .psi.), .phi., .theta. and .psi. are found within areas represented by .phi.=-5 to 5.degree., .theta.=136 to 146.degree., and .psi.=21 to 30.degree.; andwhen .psi..ltoreq.25.5, a relationship between a normalized thickness h/.lambda. (%) where a thickness, h, of said interdigital electrode is normalized with a wavelength .lambda. of a surface acoustic wave and said .psi. (.degree.) indicating the direction of propagation of the surface acoustic wave is given by-3.79 (h/.lambda.)+23.86.ltoreq..psi..ltoreq.-5.08 (h/.lambda.)+26.96and when .psi.>25.5, said relationship is given by4.39(h/.lambda.)+24.30.ltoreq..psi..ltoreq.3.54(h/.lambda.)+27.17.