| 摘要 |
PROBLEM TO BE SOLVED: To provide a ladder-type surface acoustic wave filter which widens the normal bandwidth while reducing the loss, and enhances the degree of suppression outside of pass-band. ! SOLUTION: A surface acoustic wave filter includes a multilayer substrate consisting of a multilayer structure of a piezoelectric film/a low sound speed film/a high sound speed film/a support substrate, and an interdigital electrode formed thereon, where first one terminal pair surface acoustic wave resonators 21 having a predetermined resonance frequency are arranged in parallel arm 22, second one terminal pair surface acoustic wave resonators 23 having a resonance frequency substantially matching the antiresonant frequency of the first resonator are arranged in a series arm 24. Furthermore, an inductance 25 is added in series with the first surface acoustic wave resonator 21. ! COPYRIGHT: (C)2015,JPO&INPIT |
