Surface acoustic wave filter

摘要

A surface acoustic wave filter includes a piezoelectric substrate, an exciting electrode formed on the piezoelectric substrate and exciting a surface acoustic wave, and a receiving electrode receiving the surface acoustic wave. Both the exciting and receiving electrodes are provided with interdigital electrode fingers having a period p. Either one of the exciting and receiving electrodes is constructed of a plurality of interdigital electrode sub-units (1, 2) having substantially the same electrode surface areas occupied by interdigital electrode fingers. The interdigital electrode sub-units are disposed in a direction perpendicular to a propagation direction of the excited surface acoustic wave and have a positional relation such that the interdigital electrode sub-units are offset to each other by (n ± 1/4)p, wherein n is an integer, in a direction parallel to the propagation direction of the surface acoustic wave.