A filter circuit includes a first input node and a second input node for receiving an input signal, and a first output node and a second output node for providing an output signal. A first series acoustic resonator is coupled in series between the first input node and the first output node. At least one coupled resonator filter (CRF) includes first and second transducers, which may be acoustically coupled to one another. The first transducer has a first electrode coupled to the first input node, a second electrode coupled to the second input node, and a first piezoelectric layer between the first electrode and the second electrode. A second transducer has a third electrode coupled to the first output node, a fourth electrode coupled to the second output node, and a second piezoelectric layer between the third electrode and the fourth electrode.

A tunable coupled resonator filter (CRF) structure is provided. Herein, the tunable CRF structure includes a ferroelectric input shunt resonator, a ferroelectric series resonator, and a ferroelectric output shunt resonator. The tunable CRF structure also includes a coupling layer that is coupled to the ferroelectric input shunt resonator, the ferroelectric series resonator, and the ferroelectric output shunt resonator. In embodiments disclosed herein, the coupling layer can be tuned by a tuning voltage to modify a parallel resonance frequency of the ferroelectric input shunt resonator and the ferroelectric output shunt resonator. As a result, it is possible to dynamically change the parallel resonance frequency of the tunable CRF structure based on various radio frequency (RF) filtering requirements.

An acoustic wave device includes first and second acoustic wave resonators, each including a piezoelectric layer and a functional electrode, and an acoustic coupling layer laminated between the piezoelectric layer of each of the first and second acoustic wave resonators. Each of the functional electrodes of the first and second acoustic wave resonators includes at least one pair of electrode fingers. In each of the first and second acoustic wave resonators, when a thickness of the piezoelectric layer is defined as d and a center-to-center distance of the electrode fingers adjacent to each other is defined as p, d/p is about 0.5 or smaller. The first and second acoustic wave resonators face each other across the acoustic coupling layer.

A laterally coupled resonator filter device includes a bottom electrode, a piezoelectric layer disposed on the bottom electrode, and a top contour electrode disposed on the piezoelectric layer. The top contour electrode includes first and second top comb electrodes. The first top comb electrode include a first top bus bar and multiple first top fingers extending in a first direction from the first top bus bar. The second top comb electrode includes a second top bus bar and multiple second top fingers extending in a second direction from the second top bus bar, the second direction being substantially opposite to the first direction such that the first and second top fingers form a top interleaving pattern providing an acoustic filter having an apodized shape.

An acoustic resonator structure comprises a piezoelectric layer having a first surface and a second surface, a first electrode disposed adjacent to the first surface, and a second electrode disposed adjacent to the second surface. The first electrode comprises a first conductive layer disposed adjacent to the piezoelectric layer and having a first acoustic impedance, and a second conductive layer disposed on a side of the first conductive layer opposite the piezoelectric layer and having a second acoustic impedance greater than the first acoustic impedance. The second electrode may be disposed between a substrate and the piezoelectric layer, and it may comprise a third conductive layer disposed adjacent to the piezoelectric layer and having a third acoustic impedance, and a fourth conductive layer disposed on a side of the third conductive layer opposite the piezoelectric layer and having a fourth acoustic impedance greater than the third acoustic impedance.

An acoustic transformer in a transmitter chain is disclosed. In one aspect, a differential power amplifier may produce a differential signal that is provided to a first transformer. A differential output of this first transformer is provided to an acoustic transformer that provides a single-ended output signal for use by an acoustic filter. By making the second transformer an acoustic transformer, the second transformer may be integrated into the same circuitry that forms the acoustic filter, thereby simplifying the die. Further, the acoustic transformer may be tuned if ferroelectric resonators are used, which provides strong out-of-band signal cancelation.

An acoustic wave filter having a coupled resonator filter is provided. The acoustic wave filter includes an acoustic coupling unit, a first unit of resonators disposed on a first side of the acoustic coupling unit, and a second unit of resonators disposed on a second side, opposite the first side, of the acoustic coupling unit. The first unit of resonators and the second unit of resonators are in an acoustic communication. The first unit of resonators includes a first resonator and a second resonator electrically coupled to the first resonator. The first resonator comprises a first electrode and a second electrode, and wherein the second electrode of the first resonator is disposed adjacent to the acoustic coupling unit and is configured to receive a signal input. A wireless device may include the acoustic wave filter.

An apparatus includes a die, a bonding layer, and a film. The die includes a semiconductor substrate, a metallization structure on the semiconductor substrate, and a dielectric material around at least a part of the metallization structure. The bonding layer is on the metallization structure. The film is attached on the bonding layer. The film includes a piezoelectric material.

The present disclosure relates to a resonator structure including stacked resonators, which share a same reflector. The disclosed resonator structure includes a first resonator and a second resonator, which is vertically stacked with the first resonator and shares a common reflector with the first resonator. Herein, the first resonator is at least composed of a first top electrode, a first piezoelectric layer underneath the first top electrode, and the common reflector underneath the first piezoelectric layer. The second resonator is at least composed of the common reflector, a second piezoelectric layer underneath the common reflector, and a second bottom electrode underneath the second piezoelectric layer. The first resonator and the second resonator are acoustically isolated from each other.