Patent ID: 7939989
Filing Date: 2011-05-10
Classification: H03H

Abstract:
1. An acoustic wave device comprising: a piezoelectric substrate having a surface for supporting an acoustic wave; a first elongate busbar and an opposing second elongate busbar; a plurality of first electrodes electrically connected to and extending transversely from the first busbar; and a plurality of second electrodes electrically connected to and extending from the second busbar, wherein the opposing busbars and the plurality of electrodes form an interdigital transducer carried on the surface of the piezoelectric substrate, wherein each of the plurality of electrodes has a first end electrically connected to one of the first and second busbars and an opposing second end having an edge spaced from the opposing busbar so as to form a gap between the edge of each electrode and the opposing busbar, the gaps proximate the opposing busbars forming a gap region extending longitudinally along the transducer, wherein the gap length dimension is at least one acoustic wavelength, each electrode within the plurality of electrodes is further defined by a first transversely extending portion proximate the electronically connected busbar and generally contained within the gap region, a second transversely extending portion proximate the edge and defining an edge region extending longitudinally along the transducer, and a third transversely extending portion of the electrode therebetween, the third transversely extending portion within a transducer center region, the second transversely extending portions within the edge regions, respectively, having a physical characteristic that is different than the third transversely extending portion within the transducer center region so as to provide a wave velocity of the acoustic wave within the longitudinally extending edge regions to be less than the wave velocity within the transducer center region, and wherein the wave velocity within the opposing gap regions is greater than a velocity in the transducer center region.