Patent ID: 6756867
Filing Date: 2004-06-29
Classification: H01L,H03H

Abstract:
A surface acoustic wave filter comprising:a piezoelectric substrate; a filter unit provided on the piezoelectric substrate, said filter unit having an odd number of at least three interdigital transducers arranged along a surface acoustic wave propagation direction, each of the at least three interdigital transducers having a pair of electrode finger sets; balanced signal terminals being connected to the pair of electrode finger sets of the center interdigital transducer of the at least three interdigital transducers; and an unbalanced signal terminal connected to one electrode finger set of each of at least two end interdigital transducers of the at least three interdigital transducers, said at least two end interdigital transducers being different from the center interdigital transducer, and being located on ends of the filter unit; the other electrode finger set of each of said at least two end interdigital transducers being connected to a ground; wherein the ground for at least one of the at least two end interdigital transducers is electrically isolated on the piezoelectric substrate from the ground for the other of the at least two end interdigital transducers.