Patent ID: 6121860
Filing Date: 2000-09-19
Classification: H03H

Abstract:
A multimode surface acoustic wave filter comprising two surface acoustic wave resonators arranged on a piezoelectric substrate in a direction perpendicular to the propagation direction of surface acoustic waves and acoustically coupled by a coupling section,each of the surface acoustic wave resonators comprising an interdigital transducer and two reflectors disposed on both sides of the interdigital transducer in a direction parallel to the propagation direction of the surface acoustic waves,the interdigital transducer having an excitation section for exciting the surface acoustic waves and a signal terminal section for inputting or outputting an electrical signal, andeach of the reflectors having a grating section and a terminal section,wherein the coupling section comprises a metal electrode having a plurality of slits arranged in the propagation direction of the surface acoustic wave, and the piezoelectric substrate is made of a material such that the velocity of SAW propagating through the coupling section is smaller in the case where the coupling section is formed of a metal electrode having a plurality of slits than in the case where the coupling section is formed of a uniform metal film.