Interdigital transducer for use in a surface acoustic wave filter
AssigneeCom Dev Ltd.
InventorRobert C. Peach
Life of this patent
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Abstract
An interdigital transducer for use in a surface acoustic wave filter has two busbars of an irregular shape to reduce the effect of internally reflected surface waves. The busbars will usually have an identical shape to one another and have stepped outer and inner edges. The distance between a portion of the outer edge and a corresponding portion of the inner edge can be constant for a particular busbar or that distance can vary. With previous busbars, the outer and inner edges are linear and each busbar has a rectangular shape.
Claims8
An interdigital transducer for use in a surface acoustic wave filter, said transducer comprising a thin film of metal pattern on a piezoelectric substrate, said pattern being shaped so that the transducer has two busbars with a plurality of electrodes extending between the busbars, the electrodes being parallel to one another, each electrode having a break, the transducer being connected within the filter so that when voltage is applied across the busbars, electric fields between the electrodes generate surface acoustic waves, each busbar having an inner edge and an outer edge, the inner edge extending between each of the electrodes, said outer edge having outermost portions, all outermost portions being parallel to said inner edge, said inner and outer edges having a non-linear shape in the form of a pattern and being shaped relative to one another to reduce the effect of internally reflected surface waves said pattern being repeated throughout said filter.
Dependencies are inferred from the claim text.