Wave transmission lines and networks – Coupling networks – Delay lines including elastic surface wave propagation means
Patent
1977-09-14
1979-07-24
Smith, Alfred E.
Wave transmission lines and networks
Coupling networks
Delay lines including elastic surface wave propagation means
310313, 333194, 333196, H03H 904, H03H 932, H03H 930, H01L 4110
Patent
active
041624653
ABSTRACT:
Applicants discovered that by employing selected transducer geometries, such as unbalanced dual-finger geometries, certain reflections, called "Mechanical electrical loaded" (MEL) reflections, can be generated which tend to cancel reflected waves inherently generated by surface acoustic wave devices.
In particular, the disclosure is directed to a transducer for a surface acoustic wave device adapted for coupling to an electrical load and/or source. A pair of interdigitated comb electrodes are formed on an acoustic wave propagating substrate, for example a piezoelectric substrate. Means, such as input or output terminals, are provided for applying an electrical load and/or source across the pair of comb electrodes. Each of the comb electrodes has a plurality of interdigitated electrode fingers. The width of at least some of the adjacent fingers of the electrodes are different and are selected as a function of the impedance of the load and/or source to produce mechanical electrical loaded (MEL) reflections in said substrate which tend to cancel regeneration wave (RW) reflections generated at the transducer in the substrate. In the preferred embodiment of the invention, each of the comb electrodes has at least two adjacent electrode fingers of different widths, and preferably has a plurality of adjacent finger pairs of different widths.
REFERENCES:
patent: 3936774 (1976-02-01), Mellon et al.
patent: 3990023 (1976-11-01), Kodama
Hanma Kentaro
Hunsinger Bill J.
Novack Martin
Nussbaum Marvin
Smith Alfred E.
University of Illinois Foundation
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