University of Illinois

Donald C Malocha

Bill J Hunsinger

A surface acoustic wave device having a unidirectional input transducer is provided with an input tuning circuit which eliminates the reactive portions of the device's input impedance. The input transducer has a pair of input ports, each of which exhibits an impedance A.angle..phi.. A series tuning circuit including reactances having a magnitude of A(sin.phi.+cos.phi.) and A(sin.phi.-cos.phi.) respectively, is connected to the input ports. An alternative parallel reactive tuning circuit is disclosed whose reactances are A/(sin.phi.+cos.phi.) and A/(sin.phi.-cos.phi.) respectively.

Tuned unidirectional surface wave transducer

A transducer for a surface acoustic wave device. In accordance with an embodiment of the invention, there is provided an acoustic wave propagating substrate and first and second spaced elongated conductive fingers disposed on the substrate. A layer of dielectric material is formed over the first and second fingers. A first electrode is formed on the dielectric layer above the first finger, the first electrode being proportioned to oppose a predetermined portion of the first finger. A second electrode is formed on the dielectric layer above the first finger, the second electrode being spaced from the first electrode and proportioned to oppose another predetermined portion of the first finger. A third electrode is formed on the dielectric layer above the second finger, the third electrode being proportioned to oppose a predetermined portion of the second finger. A fourth electrode is formed on the dielectric layer above the second finger, the fourth electrode being proportioned to oppose another predetermined portion of the second finger. A plurality of input/output (i.e., input or output) terminals are provided, and means are provided for coupling the input/output terminals to the electrodes.

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Urbana, IL, United States of America

Donald C Malocha