Granted Patent B2

US 12,224,736 · App. 17/905,869 · Granted Feb 11, 2025

Inventors: Leland P. Solie (Chetek, WI); Jacqueline H. Hines (Annapolis, MD); Andrew T. Hines (Annapolis, MD)

Assignee: SenSanna Incorporated

H03H9/64H03H9/02858H03H9/14547H03H9/14558

Abstract

Claims (75)

1. A surface acoustic wave (SAW) device comprising:

a piezoelectric substrate;

at least one SAW element comprising an interdigital transducer (IDT);

said at least one IDT configured to launch acoustic waves onto said piezoelectric substrate as a combined wavefront that extends across an overall acoustic aperture;

wherein said overall acoustic aperture is divided spatially into a set of acoustic tracks parallel to the direction of acoustic wave propagation;

wherein the portion of the combined wavefront propagating in each acoustic track is a wavelet;

wherein the combination of all the wavelets propagating in each track comprises the overall wavefront; and

a stepped acoustic wave delay modification element, comprising:

multiple regions within the acoustic tracks;

wherein the multiple regions include two or more film regions in which a thin film of a material that will alter the SAW velocity is formed on the surface of said piezoelectric substrate; and

wherein lengths of the two or more film regions vary from track to track to create steps in the delay of the wavelets emerging from the acoustic tracks; and

wherein the combined wavefront comprising wavelets from all of the acoustic tracks emerging from said stepped acoustic wave delay modification element is spread out in time to implement a transversal filter impulse response function; and

at least one additional SAW element configured to interact with said combined wavefront across the entire aperture.

2. A SAW device as in claim 1 ;

wherein said thin film of the material that will alter the SAW velocity is selected from among the material classes of metals, semiconductors, nanostructured materials, or dielectrics.

3. A SAW device as in claim 1 ;

wherein the difference in the length of the film region between each acoustic track and the acoustic track with the next longer film region is a length that introduces a delay equal to one period of the acoustic wave at the center frequency of operation of the stepped acoustic wave delay modification element;

wherein the wavelets emerging from all of the acoustic tracks are in phase; and

wherein the combined wavefront comprised of wavelets from all of the acoustic tracks emerging from said stepped acoustic wave delay modification element is spread out in time to implement a desired transversal filter impulse response function.

4. A SAW device as in claim 1 , further comprising

wherein the width of each acoustic track within said stepped acoustic wave delay modification element is modified to alter the amount of energy contained in the wavelet emerging from said track, relative to the other wavelets, to implement apodization or weighting of wavelets emerging at different delay times; and

wherein the combined wavefront comprising wavelets from all of the acoustic tracks emerging from said stepped acoustic wave delay modification element is spread out in time and amplitude weighted to implement a desired transversal filter impulse response function.

5. A SAW device as in claim 1 ;

wherein said at least one IDT further comprises a tapered transducer.

6. A SAW device as in claim 1 ;

wherein said at least one IDT further comprises a step-tapered transducer.

7. A SAW device as in claim 1 ;

wherein the difference in the length of the film region between each acoustic track and the acoustic track with the next longer film region is a length that introduces a delay equal to either an integer multiple of one period of the acoustic wave (Mτ) or a delay that differs by half a period (2M±1)τ/2 from said integer multiple of one period of the acoustic wave at the center frequency of operation of said stepped acoustic wave delay modification element;

wherein the wavelets emerging from certain acoustic tracks are in phase with wavelets emerging from certain other acoustic tracks; and

wherein the wavelets emerging from other certain acoustic tracks are out of phase with wavelets emerging from still other certain other acoustic tracks and cancel; and

wherein the combined wavefront comprising wavelets from all of the acoustic tracks emerging from said stepped acoustic wave delay modification element is spread out in time phase modulated to implement a coded sequence.

8. A SAW device as in claim 1 ;

wherein the difference in the length of the film region between each acoustic track and the acoustic track with the next longer film region is a length that introduces a delay that varies from track to track;

wherein the step in length of the film region between each acoustic track and the acoustic track with the next longer film region is given by λ i V/ΔV, where λ i is the local wavelet frequency, V is the free surface SAW velocity, and ΔV is the change in wave speed caused by the presence of the film;

wherein the wavelets emerging from each acoustic track are at different frequencies than the wavelets emerging from certain other acoustic tracks; and

wherein the combined wavefront comprising wavelets from all of the acoustic tracks emerging from said stepped acoustic wave delay modification element is spread out in both time and frequency to implement a dispersive transversal filer impulse response function.

9. A SAW sensor-tag device, comprising

a SAW device as in claim 1 , further comprising

an external impedance varying sensor electrically connected across one of said at least one additional SAW element;

wherein variation of the impedance of said impedance varying sensor is indicative of at least one parameter to be measured; and

wherein changes in the impedance of said impedance varying sensor cause changes in the amplitude of the surface acoustic wave response produced by said at least one additional SAW element;

whereby a SAW sensor-tag device that measures at least one parameter is realized.

10. A SAW device as in claim 1 , wherein

the regions within each acoustic track that are coated with a thin film of a material that will alter the SAW velocity are shaped like rectangles;

wherein the long side of each rectangle is oriented parallel to the direction of the acoustic tracks which is also the direction of acoustic wave propagation.

11. A SAW device as in claim 1 , wherein

the regions within each acoustic track that are coated with a thin film of a material that will alter the SAW velocity are shaped like parallelograms;

wherein the long side of each parallelogram is oriented parallel to the direction of the acoustic tracks which is also the direction of acoustic wave propagation.

12. A SAW device as in claim 1 , wherein

the regions within each acoustic track that are coated with a thin film of a material that will alter the SAW velocity are arranged such that one end of all the film regions are lined up at one distance along the direction of acoustic wave propagation from the center of said at least one IDT.

13. A SAW device as in claim 1 , wherein

the regions within each acoustic track that are coated with a thin film of a material that will alter the SAW velocity are arranged such that the ends of each of the film regions are staggered at two or more different distances along the direction of acoustic wave propagation from the center of said at least one IDT.

14. A SAW device as in claim 1 , wherein

the regions within each acoustic track that are coated with a thin film of a material that will alter the SAW velocity are arranged in order of increasing length across the acoustic aperture.

15. A SAW device as in claim 1 , wherein

the regions within each acoustic track that are coated with a thin film of a material that will alter the SAW velocity are shuffled transversely to the direction of acoustic wave propagation such that they are not arranged in order of increasing length across the acoustic aperture.

16. A SAW device as in claim 1 , wherein

the at least one additional SAW element with a uniform beam across the entire aperture to interact with said combined wavefront is an interdigital transducer.

17. A SAW device as in claim 1 , wherein

the at least one additional SAW element with a uniform beam across the entire aperture to interact with said combined wavefront is a reflector.

18. A SAW device as in claim 1 , wherein

the at least one additional SAW element with a uniform beam across the entire aperture to interact with said combined wavefront is a multi strip coupler.

19. A surface acoustic wave (SAW) device comprising:

a piezoelectric substrate;

at least one SAW element comprising an interdigital transducer (IDT);

said at least one IDT configured to launch acoustic waves onto said piezoelectric substrate as a combined wavefront that extends across an overall acoustic aperture;

wherein said overall acoustic aperture is divided spatially into a set of acoustic tracks parallel to the direction of acoustic wave propagation

wherein the portion of the combined wavefront propagating in each acoustic track is a wavelet;

wherein the combination of all the wavelets propagating in each track comprises the overall wavefront; and

a stepped acoustic wave delay modification element, comprising:

multiple regions within the acoustic tracks;

wherein the multiple regions include two or more thin film regions in which a thin film of a material that will alter the SAW velocity is formed on the surface of said piezoelectric substrate; and

wherein lengths of the two or more film regions vary from track to track to create steps in the delay of the wavelets emerging from the acoustic tracks; and

wherein the combined wavefront comprising wavelets from all of the acoustic tracks emerging from said stepped acoustic wave delay modification element is spread out in time to implement a transversal filter impulse response function; and

at least two additional SAW elements with individual acoustic apertures that each cover a portion of the entire aperture over which the combined wavefront exists, each of the at least two additional SAW elements being configured to interact with a portion of said combined wavefront.

Assignments (1)

Continuity (2)

References Cited (14)