Abstract: A film bulk acoustic wave resonator (FBAR) comprises a recessed frame region including an undulating perimeter.

Abstract: Embodiments of this disclosure relate to multiplexers that include acoustic wave filters for filtering radio frequency signals. In certain embodiments, a multiplexer includes a first acoustic wave filter including bulk acoustic wave resonators and a second acoustic wave filter including multilayer piezoelectric substrate surface acoustic wave resonators. The second acoustic wave filter can have a second pass band that is above a first pass band of the first acoustic wave filter. Related acoustic filter assemblies, packaged radio frequency modules, wireless communication devices, and methods are disclosed.

Abstract: Aspects of this disclosure relate to acoustic wave filters that include a Lamb wave resonator and a second acoustic wave resonator that is a different type of acoustic wave resonator than the Lamb wave resonator. The different type of resonator can be a film bulk acoustic wave resonator for example. Some embodiments of this disclosure relate to an acoustic wave filter that includes the Lamb wave resonator and the second acoustic wave resonator. Some embodiments of this disclosure related to different respective acoustic wave filters including the Lamb wave resonator and the second acoustic wave resonator, in which the Lamb wave resonator and the second acoustic wave resonator an implemented on a common substrate.