University of Illinois

The Magnavox Company

Harris Corporation

Bill J Hunsinger

Kentaro Hanma

Donald C Malocha

Jerry H Peppler

Roger D Fildes

Frederick Y Cho

A surface acoustic wave (SAW) device is disclosed. The SAW device includes input and output transducers disposed in spaced acoustic tracks on a piezoelectric substrate material, and a multi-strip coupler for translating the acoustic beam generated by the input transducer into the acoustic track in which the output transducer is located. The multi-strip coupler is designed so as to minimize the influence of Fresnel peaks found to exist in the amplitude profile of the acoustic beam in the output acoustic track. The multi-strip coupler is longer than in the past, and includes a central fanned region for providing well defined acoustic boundaries whose locations do not vary from device to device.

Surface acoustic wave device having improved multi-strip coupler

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.

Surface acoustic wave device with reflection suppression

Applicants have discovered that the performance of Surface Acoustic Wave Resonators can be markedly improved by digressing from the accepted techniques of sensing standing waves set up by resonation in the SAW device. Applicants have developed a SAW resonator which employs one or more unidirectional transducers which are sensitive to traveling rather than standing waves. This construction obviates the deletevious action of direct, broad band, input to output coupling and avoids the high position sensitivity which occurs when bidirectional transducers are utilized to sense standing wave patterns.

Surface acoustic wave resonator

An acoustic surface wave device having a substrate of a material capable of propagating acoustic surface wave energy. At least one electro-acoustic transducer coupled to a region of a surface of the substrate. The transducer has a first and a second bus bar positioned parallel and a distance from each other. A plurality of electrodes extend from each bus bar. The electrodes from the first bus bar are opposite to the electrodes of the second bus bar with the electrodes from one of the bus bars being forked and surrounding the electrode located in an opposite relationship thereto, thus, reducing substantially any synchronous reflections.

Acoustic surface wave device with improved 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.

Capacitive tap weighted surface acoustic wave transducers

Apparatus and method for providing electro-acoustic transducers of an acoustic surface wave device with an increased density of transducer elements. An increased density of transducer elements provides more accurate generation and reproduction of a desired frequency response above the design center frequency. By providing the sets of transducer elements which exchange signals by means of electro-acoustic surface waves with different densities of transducer elements, the transfer of undesired frequency components, introduced by the oversampled density of the transducer element sets, is reduced.

Apparatus and method for oversampled transducers in acoustic surface

Apparatus and method for phase-encoding electro-acoustic electro-acoustic elements, elements of an acoustic surface wave device to provide preselected transducer characteristics. By altering the position of a transducer element or portions of a transducer element, the phase of the acoustic wave propagated from, or the phase of the electrical signal received by the transducer element can be varied by an amount determined by the velocity of propagation of the acoustic wave. By altering the location of the electro-elements, or portions thereof, from a position determined for example by amplitude-encoding techniques, a resultant signal produced by a plurality of electro-acoustic elements, element portions, or combination of elements and element portions can provide the preselected transducer characteristics. In addition, the elements or element portions can be located such that the overlap amplitude between adjacent electro-acoustic elements is substantially a constant, providing increased directionality for acoustic waves orignating at the transducer. According to one embodiment, each electro-acoustic transducer can be phase-encoded permitting both an input and an output transducer to be phase-encoded with preselected characteristics. According to a second embodiment, the elements or portions thereof of a first transducer are displaced relative to elements or portions thereof of a second transducer to provide appropriate device phase-encoding.

Growing community of inventors

Mahomet, IL, United States of America

Bill J Hunsinger