Abstract: Acoustic resonators with enhanced boundary conditions are disclosed. In an example aspect, a resonator includes a volume of piezoelectric material including an upper surface and a lower surface. The resonator also includes a bottom electrode extending along a portion of the lower surface of the volume of piezoelectric material. The resonator further includes a multi-layered top electrode extending along a portion of the upper surface of the volume of piezoelectric material. The multi-layered top electrode includes an active region including an interface layer of a first thickness, where the active region overlaps a portion of the bottom electrode. The multi-layered top electrode also includes a frame region including the interface layer of a second thickness, where the second thickness is greater than the first thickness. The multi-layered top electrode further includes an outer region including the interface layer of a third thickness, where the third thickness is less than the second thickness.

Abstract: Example implementations of a bulk acoustic wave resonator with an optimized outer perimeter are disclosed. In an example aspect, a resonator includes a truncated-ellipsoid-shaped active region. The active region includes an outer electrode disposed as a first layer of the active region. The active layer also includes a piezoelectric layer disposed as a second layer of the active region with the piezoelectric layer disposed interior to the outer electrode. The active layer further includes an inner electrode disposed as a third layer of the active region with the inner electrode disposed interior to the piezoelectric layer.

Abstract: Acoustic resonators with enhanced boundary conditions are disclosed. In an example aspect, a resonator includes a volume of piezoelectric material including an upper surface and a lower surface. The resonator also includes a bottom electrode extending along a portion of the lower surface of the volume of piezoelectric material. The resonator further includes a multi-layered top electrode extending along a portion of the upper surface of the volume of piezoelectric material. The multi-layered top electrode includes an active region including an interface layer of a first thickness, where the active region overlaps a portion of the bottom electrode. The multi-layered top electrode also includes a frame region including the interface layer of a second thickness, where the second thickness is greater than the first thickness. The multi-layered top electrode further includes an outer region including the interface layer of a third thickness, where the third thickness is less than the second thickness.

Abstract: Example implementations of a bulk acoustic wave resonator with an optimized outer perimeter are disclosed. In an example aspect, a resonator includes a truncated-ellipsoid-shaped active region. The active region includes an outer electrode disposed as a first layer of the active region. The active layer also includes a piezoelectric layer disposed as a second layer of the active region with the piezoelectric layer disposed interior to the outer electrode. The active layer further includes an inner electrode disposed as a third layer of the active region with the inner electrode disposed interior to the piezoelectric layer.