Patent ID: 7728699
Filing Date: 2010-06-01
Classification: H03H

Abstract:
1. An acoustic wave filter device comprising: a piezoelectric body; a first IDT arranged on the piezoelectric body; second and third IDTs respectively arranged on both sides of the first IDT in an acoustic wave propagating direction in which an acoustic wave propagates; and first and second reflectors respectively arranged on both side of a portion of the piezoelectric body in which the first to third IDTs are provided in the acoustic wave propagating direction; wherein at portions in which the first, second, and third IDTs are located adjacent to each other in the acoustic wave propagating direction, an interval of electrode fingers of portions of the first, second, and third IDTs at end portions adjacent to an adjacent one of the first, second, and third IDTs is narrower than an interval of electrode fingers of the remaining portions of the first, second, and third IDTs to thereby define narrow pitch electrode finger portions; the acoustic wave filter device is a longitudinally coupled resonator acoustic wave filter device that utilizes an inter-IDT resonance mode; and apodization weights are assigned in the first, second, and third IDTs having the narrow pitch electrode finger portions at portions other than the narrow pitch electrode finger portions, such that an electrode finger overlap width sequentially changes in the acoustic wave propagating direction and portions located at end portions adjacent to the narrow pitch electrode finger portions have a maximum electrode finger overlap width.