Surface acoustic wave filter, surface acoustic wave device using the filter, and communication device using the filter or the device

摘要

A longitudinally coupled resonator type surface acoustic wave filter includes a small pitch electrode finger portion having electrode fingers of which the pitch is smaller than that of the other electrode fingers. The small pitch electrode finger portion is provided in the end of at least one of interdigital transducers which is adjacent to the other interdigital transducer. Moreover, the small pitch electrode finger portion includes two adjacent electrode fingers in at least one position thereof which are electrode-inverted so that the polarities of the two adjacent electrode fingers are made the same.