Piezoelectric thin-film filter

摘要

A piezoelectric thin-film filter includes a first electrode pair having two or more first electrode fingers disposed on one main surface of a piezoelectric thin film and second electrode fingers disposed on the other main surface of the piezoelectric thin film so as to face the first electrode fingers. A second electrode pair includes two or more third electrode fingers disposed on the main surface such that the third electrode fingers and the first electrode fingers are disposed alternately with gaps therebetween and fourth electrode fingers disposed on the other main surface so as to face the third electrode fingers with the piezoelectric thin film therebetween. Insulating films are provided between the first and third electrode fingers. Each of the center-to-center distances Wa+Wm and Wf+Wm between the first and third electrode fingers that are disposed alternately is larger than a value twice the thickness T of the piezoelectric thin film.