ELASTIC SURFACE WAVE FILTER

摘要

PROBLEM TO BE SOLVED: To provide a means for widening the band width of a primary-tertiary longitudinally-coupled double mode elastic surface wave filter and also reducing the insertion loss. SOLUTION: This longitudinally-coupled multiple module elastic wave filter is constituted by arranging a plurality of ID electrodes in the direction of propagation of surface waves on the main surface of a piezoelectric substrate. In a section where adjacent IDT electrodes are adjoining each other, electrode fingers are disposed at narrower pitches than those of the electrode fingers in a section excluding the section where they are adjoining each other.