Patent ID: 7154360
Filing Date: 2006-12-26
Classification: H03H

Abstract:
1. A filter comprising: a piezoelectric substrate; and a plurality of interdigital transducers (IDTs) formed on the piezoelectric substrate, at least one of the IDTs having a main electrode finger pattern that is weighted, and the at least one of the IDTs also having a sub electrode finger pattern that is connected in parallel to the main electrode finger pattern, and generates a surface acoustic wave that cancels a surface acoustic wave caused by leakage electric fields generated in the main electrode finger pattern, another one of the IDTs being located in a propagation direction in which a surface acoustic wave generated by the main electrode finger pattern of the at least one of the IDTs is propagated, a first aperture length of the another one of the IDTs being arranged so as to overlap, in the propagation direction, with a second aperture length of the main electrode finger pattern of the at least one of the IDTs and a third aperture length of the sub electrode finger pattern of the at least one of the IDTs, the second and third aperture lenaths extending in a direction perpendicular to the propagation direction.