Bulk acoustic wave (BAW) reflector and resonator structures, devices and systems

An electric filter cmprising a plurality of bulk acoustic wave resonators over a substrate, in which the plurality of bulk acoustic wave resonators includes at least a first bulk acoustic wave resonator, and in which the first bulk acoustic wave resonator includes at least:

• a stack including at least a first piezoelectric layer, a second piezoeletric layer, a third piezoelectric layer, a fourth piezoelectric layer having a fourth piezoelectric axis orientation, and a fifth piezoelectric layer having a fifth piezoelectric axis orientation that substantially opposes the fourth piezoelectric axis orientation of the fourth piezoelectric layer;
• and
• a first multilayer acoustic reflector including at least a first triplet of metal electrode layers electrically and acoustically coupled with the fourth piezoelectric layer and the fifth piezoelectric layer of the stack to facilitate exciting a main resonant frequency of the first bulk acoustic wave resonator in one of a super high frequency band and an extremely high frequency band.

A bulk acoustic wave resonator comprising:

• a plurality of piezoelectric layers having alternating parallel and antiparallel piezoelectric axis orientations, the plurality of piezoelectric layers having respective thicknesses, the respective thicknesses facilitating a main acoustic resonance frequency of the bulk acoustic wave resonator in one of a super high frequency band and an extremely high frequency band, the plurality of piezoelectric layers including at least a first piezoelectric layer, a second piezoelectric layer, a third piezoelectric layer, a fourth piezoelectric layer, and a fifth piezoelectric layer;
• and
• a first multilayer acoustic reflector electrically interfacing with the plurality of piezoelectric layers, the first multilayer acoustic reflector including at least a first triplet of metal electrode layers.