Acoustic wave resonators having Fresnel surfaces
Acoustic wave resonators having Fresnel features are disclosed. An example integrated circuit package includes an acoustic wave resonator, the acoustic wave resonator including a Fresnel surface. In some examples, the Fresnel surface includes a plurality of recessed features and/or protruding features at different locations on the Fresnel surface, each of the plurality of features to confine main mode acoustic energy from a respective portion of the Fresnel surface in a central portion of the acoustic wave resonator.
1. An integrated circuit package, comprising:
an acoustic wave resonator including: a piezoelectric material having an edge, the edge including a Fresnel surface; a first electrode having a first one or more fingers on the piezoelectric material; and a second electrode having a second one or more fingers on the piezoelectric material, the second one or more fingers interlaced with the first one or more fingers.
2. The integrated circuit package of claim 1 , wherein the piezoelectric material has a central portion, and the Fresnel surface includes protruding features that confine main mode acoustic energy in the central portion.
3. The integrated circuit package of claim 2 , wherein distances between the protruding features change across the Fresnel surface.
4. The integrated circuit package of claim 2 , wherein at least one of the protruding features has at least one of a sloped surface, a rectangular shape, or a stair-stepped shape.
5. The integrated circuit package of claim 1 , further comprising an integrated circuit electrically coupled to the acoustic wave resonator.
6. An acoustic wave resonator, comprising:
a piezoelectric material having a central portion and first and second edges, the first and second edges having protruding features that confine main mode acoustic energy from different portions of the piezoelectric material in the central portion;
a first electrode having a first one or more fingers on the piezoelectric material; and
a second electrode having a second one or more fingers on the piezoelectric material, the second one or more fingers interlaced with the first one or more fingers.
7. The acoustic wave resonator of claim 6 , wherein distances between the protruding features change across the first edge.
8. The acoustic wave resonator of claim 6 , wherein at least one of the protruding features has at least one of a curved edge, a straight edge, a triangular shape, a rectangular shape, or a stair-stepped shape.
9. The acoustic wave resonator of claim 6 , wherein the protruding features are patterned by a semiconductor fabrication process.