Abstract: Aspects of the disclosure relate BAW resonator with improved performance, RF-filter. A BAW resonator with improved performance is provided. The resonator includes a piezoelectric material sandwiched between a first electrode and a second electrode. The piezoelectric material is provided as a monocrystalline material having a particular orientation defined by a particular Euler angle such as the piezoelectric material being LiTaO3 and having an orientation with Euler angles selected from [0°±5°; 130°±15°; n°±5°], or a symmetrical equivalent.

Abstract: Certain aspects of the present disclosure generally relate to a filter, such as an acoustic resonator filter. An example filter generally includes a first series resonator coupled between a first port of the filter and a second port of the filter, the first series resonator including a first piezoelectric layer disposed between a first electrode and a second electrode of the first series resonator. The filter also includes a first shunt resonator coupled between a first node of the filter and a reference potential node of the filter, the first shunt resonator including a second piezoelectric layer disposed between a third electrode and a fourth electrode of the first shunt resonator. The first node is coupled between the two ports, and the second piezoelectric layer's thickness is greater than the first piezoelectric layer's thickness.

Abstract: A BAW resonator is provided wherein the top electrode (TE) has an outer flap (OF). The flap extends away from the active resonator region (AR) and has a projecting section that runs at a level above the piezoelectric layer (PL) that is higher than the level of the top electrode at any of the inwardly located areas enclosed by the outer flap. The higher level is formed by an intermediate step-forming material (SM) arranged between piezoelectric layer and top electrode in the outer flap. The step forming material comprises a structured layer of an acoustic impedance that is low w.r.t. the impedance of the top electrode and 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.

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.