Mode analysis of longitudinal multi mode SAW resonator filter

This paper describes the mode analysis for a longitudinal multi mode SAW resonator filter having 5 IDTs between the grating reflectors. The mode analysis is carried out at several conditions and frequencies, focusing on trap response. At the trap canceling condition, two resonant modes coincide in frequency and degenerate. Furthermore, at the fundamental resonant mode, SAW distribution at the center of electrode is distorted to be undulatory. In order to unify the SAW distribution of the fundamental mode, electrode pitches are adjusted partially. The developed balanced DCS-Rx filter realized low insertion loss of under 2 dB successfully.