Ladder-type surface acoustic wave filter for portable telephone, sets frequency difference of intermediate serial and parallel arm resonators to exceed that between front and back serial and parallel arm resonators

摘要

Serial and parallel arm resonators (6a-6c,7a-7c) are respectively connected to serial and parallel arms (4,5) of wave filter. Difference is resonance frequency ( DELTA f) of resonators (6b,7c) is set greater than that between resonators (6a,6c,7a,7c), respectively.