SURFACE ACOUSTIC WAVE DEVICE, AND MOBILE COMMUNICATION DEVICE AND SENSOR BOTH USING SAME

摘要

A surface acoustic wave device (SAW) such as a surface acoustic wave resonator or a filter having a loss reduced to a minimum and a sharpness. A piezoelectric substrate is cut out at a cut angle at which a leaky surface acoustic wave (LSAW) can be exited. IDT electrodes having predetermined thickness and an electrode finger pitch (p) and a reflector are provided on the piezoelectric substrate. The sound velocity of the SAW used is slower than the sound velocity (vb) of the slow transverse wave propagated through the piezoelectric substrate, and the relation 2xp<=vb/f where f is the resonance frequency is satisfied. Therefore the RSAW not causing any propagation loss can be used, and the insertion loss and sharpness are improved compared to conventional SAW devices of LSAW type.