SURFACE ACOUSTIC WAVE FILTER AND ANTENNA COMMON UNIT EMPLOYING IT

摘要

A plurality of surface acoustic wave resonators (15-20), each consisting of an interdigital electrode and a grating reflector, are connected on a piezoelectric substrate (12). A dielectric film (14) is formed on the surface of at least one of the surface acoustic wave resonators (15-20), and the dielectric film (14) is not formed on the surface of at least one acoustic wave resonator. Thus, it is possible to obtain an SAW filter having a low in-band insertion loss, good sharpness and a wide band.