Patent ID: 7005948

Claim:
A surface acoustic wave device comprising: a first longitudinally coupled resonator type surface acoustic wave element including at least three interdigital transducers arranged along the direction of transmission of a surface acoustic wave, each of the interdigital transducers being provided with a plurality of electrode fingers; and a second longitudinally coupled resonator type surface acoustic wave element including at least three interdigital transducers arranged along the direction of transmission of the surface acoustic wave, each of the interdigital transducers of the second longitudinally coupled resonator type surface acoustic wave element being provided with a plurality of electrode fingers, the first longitudinally coupled resonator type surface acoustic wave element and the second longitudinally coupled resonator type surface acoustic wave element being cascaded to each other and being arranged on a piezoelectric substrate; wherein at least one of the interdigital transducers of each of the first and second longitudinally coupled resonator type surface acoustic wave elements has a narrow pitch electrode finger portion located near the adjacent interdigital transducer, the pitch of the electrode fingers of the narrow pitch electrode finger portion being smaller than the pitch of the other electrode fingers; the number and the pitch of the electrode fingers of the narrow pitch electrode finger portion of the first longitudinally coupled resonator type surface acoustic wave element are different from the number and the pitch of the electrode fingers of the narrow pitch electrode finger portion of the second longitudinally coupled resonator type surface acoustic wave element; and each of the first and second longitudinally coupled resonator type surface acoustic wave elements includes three interdigital transducers, and the number of the electrode fingers of a central interdigital transducer of the first longitudinally coupled resonator type surface acoustic wave element is different from the number of the electrode fingers of a central interdigital transducer of the second longitudinally coupled resonator type surface acoustic wave element.