PIEZOELECTRIC THIN FILM FILTER

摘要

There is provided a piezoelectric thin film filter capable of widening the band. A first electrode pair (20) has at least two first electrode fingers (24) arranged on a first main surface (14a) of a piezoelectric thin film (14) and a second electrode finger (22) arranged on a second main surface (14b) of the piezoelectric thin film (14) so as to oppose to the first electrode fingers (24). A second electrode pair (30) has at least two third electrode fingers (34) arranged on the first main surface (14a) of the piezoelectric thin film (14) in such a manner that the first electrode fingers (24) and the third electrode fingers (34) are alternately arranged at a predetermined interval and a fourth electrode finger (32) arranged on the second main surface (14b) of the piezoelectric thin film (14) via the piezoelectric thin film (14) so as to oppose to the third electrode fingers (34). On the first main surface (14a) of the piezoelectric thin film (14), an insulation film (16) is arranged between the first electrode fingers (24) and the third electrode fingers (34) which are alternately arranged at an interval. The distance between the center of the first electrode finger (24) and the center of the third electrode finger (36) which are alternately arranged Wa + Wm, Wf + Wm is greater than the thickness T of the piezoelectric thin film (14) multiplied by 2.