Alternative structure for realizing a transversal saw filter

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.