Patent ID: 12255613

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents various descriptions of specific embodiments. However, the innovations described herein can be embodied in a multitude of different ways, for example, as defined and covered by the claims. In this description, reference is made to the drawings where like reference numerals can indicate identical or functionally similar elements. It will be understood that elements illustrated in the figures are not necessarily drawn to scale. Moreover, it will be understood that certain embodiments can include more elements than illustrated in a drawing and/or a subset of the elements illustrated in a drawing. Further, some embodiments can incorporate any suitable combination of features from two or more drawings.

With the explosive growth of mobile communication, the frequency spectrum is becoming crowded. This can generate demanding specifications for radio frequency (RF) filters and duplexers with steep roll-off, low temperature drift, low insertion loss, miniature size, the like, or any combination thereof. Bulk acoustic wave (BAW) filters can include a film bulk acoustic resonator (FBAR) filters and/or a solidly mounted resonator (SMR). Such BAW filters can fulfill the demanding specifications for RF filters in certain applications. Surface acoustic wave (SAW) filters typically have higher frequency drift over temperature. Such SAW filters may encounter difficulty in meeting stringent filter specifications. However, BAW filters are generally more expensive and larger in size than SAW filters.

Aspects of this disclosure are related to a surface acoustic wave device with a multi-layer piezoelectric substrate that includes a lithium-based piezoelectric layer, such as a lithium tantalate layer (LT) or a lithium niobate (LN) layer, over a substrate layer and a conductive layer disposed between the piezoelectric layer and the substrate layer. The conductive layer can be in electrical communication with a grounding structure positioned over the piezoelectric layer. In some other applications, the conductive layer can be in electrical communication with a grounding structure positioned under the substrate layer.

Surface acoustic wave filters and/or duplexers including the surface acoustic wave device with a grounded conductive layer improve receive and/or transmit isolation. For example, isolation degradation can be caused by parasitic capacitance between any of the input port, the output port, and other signal pads on the piezoelectric layer. The parasitic capacitance can cause electrical coupling between the signals on the input port, the output port, and the other signal pads. A multi-layer piezoelectric substrate having a grounded conductive layer can attenuate this electrical coupling.

Acoustic wave filters can filter radio frequency (RF) signals in a variety of applications, such as in an RF front end of a mobile phone. An acoustic wave filter can be implemented with surface acoustic wave (SAW) devices. SAW devices include SAW resonators, SAW delay lines, and multi-mode SAW (MMS) filters (e.g., double mode SAW (DMS) filters). Although some embodiments may be described with reference to SAW resonators for illustrative purposes, any suitable principles and advantages disclosed herein can be applied to any other suitable type of SAW device.

FIG.1is a cross sectional view of a portion of a surface acoustic wave resonator130. As illustrated, the surface acoustic wave resonator130includes a piezoelectric layer142, a grounding structure162over the piezoelectric layer142, and one or more pads164over the grounding structure162. The piezoelectric layer142can be any suitable piezoelectric layer, such as a lithium niobate (LN) layer or lithium tantalate (LT) layer. The grounding structure162is electrically connected to ground. The grounding structure162can be any conductive structure arranged to provide a ground connection. The grounding structure162can include a conductive plate and/or one or more conductive pillars. The grounding structure162can include one or more ground pads of an acoustic wave component. The grounding structure162can include any suitable conductive material, such as copper (Cu), gold (Au), lead (Pb), aluminum (Al), silver (Ag), a conductive paste of one or more of Cu, Au, Pb, Al and Ag conductive particles with an adhesive, and the like. The one or more pads164can include any suitable pad material. The illustrated pads164can be used, for example, to connect the surface acoustic wave resonator130to a module or a circuit board.

FIG.2is a cross sectional view of a portion of a surface acoustic wave resonator132having a multi-layer piezoelectric substrate. The surface acoustic wave resonator132is like the surface acoustic wave resonator130ofFIG.1except that the piezoelectric layer142of the surface acoustic wave resonator132is over a carrier substrate152in the surface acoustic wave resonator132. The surface acoustic wave resonator132can be referred to as a multi-layer piezoelectric substrate surface acoustic wave resonator. The carrier substrate152can be a silicon substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a polycrystalline spinel substrate, or any other suitable carrier substrate. The carrier substrate152can be referred to as a support substrate, carrier wafer, or a support wafer.

FIG.3is a cross sectional view of a portion of a surface acoustic wave resonator134having a multi-layer piezoelectric substrate. The surface acoustic wave resonator134is like the surface acoustic wave resonator132ofFIG.2except that a conductive layer157is included in the surface acoustic wave device134. The illustrated conductive layer157is positioned between the carrier substrate152and the piezoelectric layer142. The conductive layer157inFIG.3is floating. The conductive layer157inFIG.3is not electrically connected to the grounding structure162. The conductive layer157can be an aluminum layer, a titanium layer, and iron layer, a copper layer, another standard material used for conductive traces, or any other suitable conductive layer.

FIG.4Ais a cross sectional view of a portion of a surface acoustic wave resonator136with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator136can be referred to as a multi-layer piezoelectric substrate surface acoustic wave resonator. The surface acoustic wave resonator136is like the surface acoustic wave resonator132ofFIG.2except that a conductive layer158is electrically connected to the grounding structure162. Accordingly, the conductive layer158is configured to be grounded. The illustrated conductive layer158is positioned between the carrier substrate152and the piezoelectric layer142. As illustrated, the conductive layer158is electrically connected to ground by a wrapping portion143of conductive material around the piezoelectric layer142such that the conductive layer158electrically connects with the grounding structure162. Accordingly, unlike the floating conductive layer157ofFIG.3, the conductive layer158can be grounded as illustrated. The wrapping portion143includes conductive material extending along at least a portion of a sidewall of the piezoelectric layer142that is included in an electrical path between the conductive layer158and the grounding structure162. The conductive layer158can be an aluminum layer, or any other suitable conductive layer. The conductive layer158can have a thickness of approximately 1 micron, of between approximately 0.5 micron and approximately 2 microns, of between approximately 10 nanometers and approximately 10 microns, or greater than 10 microns.

One wrapping portion143is illustrated on the left side of the surface acoustic wave resonator136inFIG.4A. However, in some other embodiments, the surface acoustic wave resonator136can include two or more wrapping portions. For example, the surface acoustic wave resonator136can include the wrapping portions143on the left side and the right side of the surface acoustic wave resonator136inFIG.4A. In such embodiments, there can be additional ground connections for a stronger ground connection.

FIG.4Bis a cross sectional view of a portion of a surface acoustic wave resonator137with a multi-layer piezoelectric substrate according to another embodiment. The multi-layer piezoelectric substrate of the surface acoustic wave resonator137can include a conductive layer158implemented in accordance with any suitable principles and advantages disclosed herein. As illustrated, the surface acoustic wave resonator137includes the piezoelectric layer142over the carrier substrate152. The conductive layer158is positioned between the carrier substrate152and the piezoelectric layer142. An interdigital transducer (IDT) electrode144is positioned over the piezoelectric layer142. The IDT electrode144can be in physical contact with the piezoelectric layer142as illustrated. The IDT electrode144can include aluminum (Al) or any suitable alloy thereof. The IDT electrode144can include two or more conductive layers in some instances. Such an IDT electrode144can include aluminum (Al) and another conductive layer such as molybdenum (Mo), tungsten (W), gold (Au), silver (Ag), copper (Cu), platinum (Pt), ruthenium (Ru), titanium (Ti), or the like. In some embodiments, the IDT electrode144can be a multi-layer IDT electrode.

The surface acoustic wave resonator137ofFIG.4Billustrates one approach to providing electrical communication between the conductive layer158and the grounding structure162of the acoustic wave resonator136ofFIG.4A. In the surface acoustic wave resonator137, one or more portions of the piezoelectric layer142can be removed to expose the conductive layer158during manufacture. The removed portions can be filled with conductive material160such that the conductive material160is in contact with the conductive layer158and the grounding structure162(not illustrated) that can be positioned over the piezoelectric layer142. The conductive material160is included in an electrical path between the conductive layer158and the grounding structure162. Thus, the conductive layer158is electrically connected to the grounding structure162by way of the conductive material160.

One or more etched portions of the piezoelectric layer142can be etched away and/or etched back from one or more edges of the surface acoustic wave resonator137using any suitable etching process, such as wet etching, dry etching, chemical-mechanical planarization (CMP), laser drilling, or the like. The conductive material160can be deposited in the etched portion using any suitable deposition process, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), electrochemical deposition (ECD), molecular beam epitaxy (MBE), atomic layer deposition (ALD), electron beam deposition, and the like. The conductive material160can be any suitable conductive material, such as molybdenum (Mo), tungsten (W), gold (Au), silver (Ag), copper (Cu), platinum (Pt), ruthenium (Ru), titanium (Ti), or the like.

FIG.4Cis a cross sectional view of a portion of a surface acoustic wave resonator138with a multi-layer piezoelectric substrate according to another embodiment. The multi-layer piezoelectric substrate of the surface acoustic wave resonator138can include a conductive layer158implemented in accordance with any suitable principles and advantages disclosed herein. The surface acoustic wave resonator138is like the surface acoustic wave resonator137ofFIG.4Bexcept thatFIG.4Cillustrates another approach to providing electrical communication between the conductive layer158and the grounding structure162ofFIG.4A.

In the surface acoustic wave resonator138, one or more vias166filled with conductive material provide electrical communication between the conductive layer158and the grounding structure162(not illustrated) that can be positioned over the piezoelectric layer142. The vias166are included in electrical path between the conductive layer158and the grounding structure162. Although the vias166are illustrated as filled vias, the vias166can be a conformal via (seeFIG.4F). Any other suitable conductive structure can alternatively or additionally be implemented in the electrical path between the conductive layer158and the grounding structure162. The vias166can include a through-hole via.

The vias166can be formed using any suitable via formation processes. For example, an opening can be formed through at least the piezoelectric layer142to expose the conductive layer158during manufacture. The opening can extend to the upper surface of the conductive layer158, below the surface of the conductive layer158, or the like. In an aspect, the opening can be formed using any suitable etching process. The opening can be filled with the conductive material to form the via166through the piezoelectric layer142such that the conductive material of the via166is in contact with the conductive layer158. In an aspect, the opening can be filled with the conductive material using any suitable deposition process. In an aspect, sidewalls of the opening can be lined with an electrically insulating material before filling the opening with the conductive material to form the via166through the piezoelectric layer142. The conductive material of the via166can also be in contact with the grounding structure162that can be positioned over the piezoelectric layer142to provide electrical communication between the grounding structure162and the conductive layer158through the one or more vias166.

The conductive material160can be any suitable conductive material, such as molybdenum (Mo), tungsten (W), gold (Au), silver (Ag), copper (Cu), platinum (Pt), ruthenium (Ru), titanium (Ti), aluminum (Al), or the like. Examples of insulating materials are silicon dioxide (SiO2), silicon oxynitride compounds (SiON), silicon nitride compounds (SiN), tantalum oxide (Ta2O5), aluminum oxide (Al2O3), silicon carbide (SiC), tetraethyl orthosilicate (TEOS), silicon on glass (SOG), polyimide, and the like.

FIG.4Dis a cross sectional view of a surface acoustic wave resonator138awith a multi-layer piezoelectric substrate according to another embodiment. The acoustic wave resonator138ais generally similar to the acoustic wave resonator138illustrated inFIG.4C, except that the illustrated acoustic wave resonator138aincludes a grounding structure162a. The grounding structure162ais provided over the piezoelectric layer and in electrical communication with the conductive layer158through a via166. Portions of the grounding structure162aare positioned above the IDT electrode144. The grounding structure162acan be a conductive sheet configured at a ground potential. As one example, the grounding structure162acan be a copper sheet configured at a ground potential.

FIG.4Eis a cross sectional view of a surface acoustic wave resonator138bwith a multi-layer piezoelectric substrate according to another embodiment. The acoustic wave resonator138bis generally similar to the acoustic wave resonator138aillustrated inFIG.4D, except that a grounding structure162bin the acoustic wave resonator138bincludes grounding structure portions that are spaced apart from each other. The grounding structure162bis provided over the piezoelectric layer and in electrical communication with the conductive layer158through a via166. The grounding structure162bis positioned farther from the piezoelectric layer142than the IDT electrode144. The grounding structure portions of the grounding structure162bmay be positioned laterally from the IDT electrode144. The grounding structure162bcan include conductive pillars and/or conductive pads. The grounding structure162bcan include copper in certain applications.

FIG.4Fis a cross sectional view of a portion of a surface acoustic wave resonator with a multi-layer piezoelectric substrate including a conformal via167according to another embodiment. The portion of the surface acoustic wave resonator can include a conductive layer158and a piezoelectric layer142over the conductive layer158. The conformal via167can include a conductive material that is conformally disposed at least along sidewalls of a via hole defined by portions of the piezoelectric layer142. The conductive material can be also disposed at the bottom of the via hole defined by a portion of the conductive layer158. The conductive material can be also disposed on at least a portion of the piezoelectric layer142. Accordingly, the conductive material can provide an electrical connection to another element on the piezoelectric layer142, such as an IDT electrode, that is positioned laterally from the conformal via167. The conformal via167can be utilized in accordance with any suitable principles and advantages of any of the embodiments disclosed herein. In some embodiments, the conformal via167can be used in place of, for example, the conductive material160or the via166illustrated in any ofFIGS.4B-4E. According to some other embodiments, a combination of the conformal via167and another type of via can be implemented in an acoustic wave device. For example, a conductive pillar can be provided and/or connected to the portion of the conductive material of the conformal via that is disposed on the portion of the piezoelectric layer142.

FIG.4Gis a cross sectional view of a surface acoustic wave resonator138cwith a multi-layer piezoelectric substrate according to another embodiment. As inFIGS.4B-4E, the surface acoustic wave resonator138cincludes a carrier substrate152, a piezoelectric layer142over the carrier substrate152, and a conductive layer158between the carrier substrate152and the piezoelectric layer142. The surface acoustic wave resonator138calso includes a temperature compensation layer156and a conductive material169that is conformally disposed at least along sidewalls of the piezoelectric layer142and over the temperature compensation layer156. In some other instances, one or more of a passivation layer, a dispersion adjustment layer, an air cavity, or the like can be disposed between the temperature compensation layer156and the conductive material169.

The temperature compensation layer156can be a silicon dioxide (SiO2) layer, or any other suitable temperature compensation layer. The temperature compensation layer156can be a layer of any other suitable material having a positive temperature coefficient of frequency. For instance, the temperature compensation layer156can be a tellurium dioxide (TeO2) layer or a silicon oxyfluoride (SiOF) layer in certain applications. The temperature compensation layer156can include any suitable combination of SiO2, TeO2, and/or SiOF. The temperature compensation layer156can be a passivation layer, in some applications. The conductive material169can include any suitable conductive material. The conductive material169can include, for example, molybdenum (Mo), tungsten (W), gold (Au), silver (Ag), copper (Cu), platinum (Pt), ruthenium (Ru), titanium (Ti), aluminum (Al), or the like.

The conductive material169can serve as a grounding structure. In some applications, the surface acoustic wave resonator138ccan include another grounding structure (not illustrated) over the conductive material169. The conductive material169can be included in an electrical path between the conductive layer158and the other grounding structure. Therefore, the conductive layer158can be electrically connected to a grounding structure by way of the conductive material169along sidewalls of the piezoelectric layer142.

FIG.4Hillustrates a cross sectional view of a surface acoustic wave resonator138dwith a multi-layer piezoelectric substrate according to another embodiment. The surface acoustic wave resonator138dcan be referred to as a multi-layer piezoelectric substrate surface acoustic wave resonator. As illustrated, the surface acoustic wave resonator138dincludes a carrier substrate152, a piezoelectric layer142, a grounding structure162dover the piezoelectric layer142, an interdigital transducer electrode144on the piezoelectric layer142, a conductive layer158between the carrier substrate152and the piezoelectric layer142, and one or more pads over the grounding structure162d. As illustrated, the conductive layer158is electrically connected to ground by wrapping a portion143of conductive material around the piezoelectric layer142such that the conductive layer158electrically connected with the grounding structure162d.

The one or more pads can include a signal pad164afor a signal connection and ground pads164bfor a ground connection. The ground pads164bare connected to the grounding structure162d. The grounding structure162dcan include conductive portions163a,163b,163c. The conductive portions163a,163b,163cof the grounding structure162dcan include any suitable conductive material, such as copper (Cu), gold (Au), lead (Pb), aluminum (Al), silver (Ag), a conductive paste of one or more of Cu, Au, Pb, Al, and Ag conductive particles with an adhesive, or the like. The conductive portion163acan be thicker than the IDT electrode144. The surface acoustic wave resonator138dalso includes dielectric portions172a,172bthat can provide physical support for the grounding structure162d.

FIG.4Iillustrates a cross sectional view of a surface acoustic wave resonator138ewith a multi-layer piezoelectric substrate according to another embodiment. The surface acoustic wave resonator138eis like the surface acoustic wave resonator138dillustrated inFIG.4Hexcept the conductive layer158inFIG.4Iis connected to the grounding structure162dby way of a via166.

FIG.5is a graph of transmit and receive isolation curves of acoustic wave resonators without a conduction layer as illustrated inFIGS.1-2, and an acoustic wave resonator with a floating conductive layer as illustrated inFIG.3, relative to an acoustic wave resonator with a conduction layer that is grounded as illustrated inFIG.4A. The representative LT (REF) transmit and receive isolation curves can be associated with the surface acoustic wave resonator130ofFIG.1. The representative LT/Si transmit and receive isolation curves can be associated with the surface acoustic wave resonator132ofFIG.2; and the representative LT/Conductive Layer (floating) transmit and receive isolation curves can be associated with the surface acoustic wave resonator134ofFIG.3. The representative LT/Conductive Layer (connected to GND)/Si transmit and receive isolation curves can be associated with the surface acoustic wave resonators136ofFIG.4A.

The graph illustrates that a floating conductive layer positioned between the carrier substrate152and the piezoelectric layer142can degrade isolation.FIG.5also indicates that a conductive layer between the carrier substrate152and the piezoelectric layer142can improve isolation.FIG.5illustrates that an acoustic wave resonator with a multi-layer piezoelectric substrate having a conductive layer positioned between the piezoelectric layer and the carrier substrate can suppress electronic coupling within the multi-layer substrate. The suppressed electronic coupling can improve transmit and receive isolation.

FIG.6is a cross sectional view of a portion of a surface acoustic wave resonator600with a multi-layer piezoelectric substrate illustrating conductive layer bonding positions according to an embodiment. As illustrated, the acoustic wave resonator600includes a carrier substrate606, a piezoelectric layer602over the carrier substrate606, a silicon dioxide (SiO2) layer604and a conductive layer608positioned between the piezoelectric layer602and the carrier substrate606, and an IDT electrode610over the piezoelectric layer602. The conductive layer608is configured to connect to a grounding structure for a ground connection. The carrier substrate606can be a high velocity carrier substrate, a silicon substrate, a quartz substrate, a sapphire substrate, a ceramic, a polycrystalline spinel substrate, or any other suitable carrier substrate. The silicon dioxide layer604can be a dispersion adjustment layer. The piezoelectric layer602can be can be any suitable piezoelectric layer, such as a lithium niobate layer or lithium tantalate layer. The IDT electrode610can be in physical contact with the piezoelectric layer602as illustrated. The IDT electrode610can include aluminum (Al), any suitable alloy of aluminum, molybdenum (Mo), tungsten (W), gold (Au), silver (Ag), copper (Cu), platinum (Pt), ruthenium (Ru), titanium (Ti), or the like.

FIG.6illustrates three example bonding locations for the conductive layer608. In other aspects, other bonding positions can be used. In a first illustrated location, conductive layer608is represented by conductive layer608A and positioned between the piezoelectric layer602and the silicon dioxide layer604. In an illustrated second location, conductive layer608is represented by conductive layer608B and positioned within the silicon dioxide layer604. In a third illustrated location, conductive layer608is represented by conductive layer608C and positioned between the silicon dioxide layer604and the carrier substrate606.

FIG.7is a graph comparing transmission characteristics of acoustic wave resonator600having the conductive layer608at the different bonding positions A, B, and C illustrated inFIG.6.FIG.7illustrates that transmission characteristics for an acoustic wave resonator having a multi-layer piezoelectric substrate that includes a conductive layer at bonding position A are degraded relative to an acoustic wave resonator having a multi-layer piezoelectric substrate that includes a conductive layer at bonding positions B or C. Specifically, for example, the anti-resonance of the acoustic wave resonator having the multi-layer piezoelectric substrate that includes the conductive layer at bonding position A is degraded relative to the acoustic wave resonator having the multi-layer piezoelectric substrate that includes the conductive layer at bonding positions B or C.

FIG.7further illustrates that an acoustic wave resonator having a multi-layer piezoelectric substrate that includes a silicon dioxide layer and conductive layer at bonding position C provide better transmission characteristics relative to an acoustic wave resonator having a multi-layer piezoelectric substrate that includes a silicon dioxide layer and a conductive layer at bonding positions A or B. For example, at bonding position A, the conductive layer608A is in direct contact with the piezoelectric layer602, which may degrade the electrical performance of the IDT electrode610. Because the silicon dioxide layer's permittivity is smaller than the permittivity of the piezoelectric layer602, insulation by the silicon dioxide layer604may help to improve the electrical characteristics of the IDT electrode610. Therefore, in some embodiments, it can be preferable to position a conductive layer with an insulating layer (e.g., silicon dioxide layer604) that has a sufficient thickness between the layer and the piezoelectric layer602.

Conductive layers electrically connected to grounding structures can be implemented in a variety of different multi-layer piezoelectric substrate acoustic wave devices. Examples of such acoustic wave devices will be described with reference toFIGS.8A to8C. Any of these example acoustic wave devices can be implemented in any suitable electrical connections to a grounding structure positioned above a piezoelectric layer. Alternatively or additionally, any of these example acoustic wave devices can be implemented in any suitable electrical connections to a grounding structure positioned below a carrier substrate.

FIG.8Ais a cross sectional view of a portion of a surface acoustic wave resonator153with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator153can include a multi-layer piezoelectric substrate in accordance with any suitable principles and advantages disclosed herein. As illustrated, the surface acoustic wave resonator153includes a carrier substrate152, a conductive layer158over the carrier substrate152, a dispersion adjustment layer154over the conductive layer, a piezoelectric layer142over the dispersion adjustment layer154, and an IDT electrode144on the piezoelectric layer142.

The carrier substrate152can be a silicon substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, a polycrystalline spinel substrate, or any other suitable carrier substrate. The illustrated conductive layer158is positioned between the dispersion adjustment layer154and the carrier substrate152. The conductive layer158can include an aluminum (Al) layer, any suitable aluminum (Al) alloy layer, a molybdenum (Mo) layer, a tungsten (W) layer, a gold (Au) layer, a silver (Ag) layer, a copper (Cu) layer, a platinum (Pt) layer, a ruthenium (Ru) layer, a titanium (Ti) layer, or any other suitable conductive layer. The conductive layer158can include two or more conductive layers in some instances.

The illustrated dispersion adjustment layer154is positioned between the conductive layer158and the piezoelectric layer142. The dispersion adjustment layer154can alternatively be or additionally include any suitable insulation layer, temperature compensation layer, dielectric layer and/or adhesion layer. The dispersion adjustment layer154can be a silicon nitride layer, a silicon dioxide layer, or any other suitable dispersion adjustment layer. The piezoelectric layer142can be any suitable piezoelectric layer, such as a lithium niobate (LN) layer or lithium tantalate (LT) layer. The IDT electrode144can be in physical contact with the piezoelectric layer142as illustrated. The IDT electrode144can include aluminum (Al) or any suitable alloy thereof. The IDT electrode144can include two or more conductive layers in some instances. Such an IDT electrode144can include aluminum (Al) and another conductive layer such as molybdenum (Mo), tungsten (W), gold (Au), silver (Ag), copper (Cu), platinum (Pt), ruthenium (Ru), titanium (Ti), or the like.

The conductive layer158can be in electrical communication with a grounding structure positioned over the piezoelectric layer142in the surface acoustic wave resonator153. Alternatively or additionally, the conductive layer158can be in electrical communication with a grounding structure positioned under the carrier substrate152. The conductive layer158can be referred to as a conductive layer158. In one aspect, the dispersion adjustment layer154and the piezoelectric layer142can be etched away or etched back at one or more edges of the surface acoustic wave resonator153and the etched away or etched back portions can be filled with conductive material such that the conductive material is in electrical communication with the grounding structure and the conductive layer158. In another aspect, at least one via can be formed through the piezoelectric layer142and the dispersion adjustment layer154of the surface acoustic wave resonator153such that conductive material filling the via provides electrical communication between the grounding structure and the conductive layer158.

FIG.8Bis a cross sectional view of a portion of a surface acoustic wave resonator155with a multi-layer piezoelectric substrate according to another embodiment. The surface acoustic wave resonator155can include a multi-layer piezoelectric substrate in accordance with any suitable principles and advantages disclosed herein. The surface acoustic wave resonator155is like the surface acoustic wave resonator153ofFIG.8Aexcept that the dispersion adjustment layer154is not included in the multi-layer piezoelectric substrate. Instead, a temperature compensation layer156is included in the surface acoustic wave device155. The illustrated temperature compensation layer156is positioned over the IDT electrode144. The temperature compensation layer156can be a silicon dioxide layer, or any other suitable temperature compensation layer. The temperature compensation layer156can serve as a passivation layer, in some applications. The temperature compensation layer156can bring a temperature coefficient of frequency (TCF) of the surface acoustic wave resonator155closer to zero. For instance, the piezoelectric layer142can have a negative TCF and the temperature compensation layer156can have a positive TCF. The temperature compensation layer156can have an opposite TCF as a TCF of the piezoelectric layer142.

The conductive layer158can be in electrical communication with a grounding structure positioned over the piezoelectric layer142in the surface acoustic wave resonator155. Alternatively or additionally, the conductive layer158can be in electrical communication with a grounding structure positioned under the carrier substrate152. In one aspect, at least the piezoelectric layer142can be etched away or etched back at one or more edges of the surface acoustic wave resonator155and the etched away or etched back portions can be filled with conductive material such that the conductive material is in electrical communication with the grounding structure and the conductive layer158. In another aspect, at least one via can be formed through at least the piezoelectric layer142of the surface acoustic wave resonator155such that conductive material filling the via provides electrical communication between the grounding structure and the conductive layer158. In some instances, the temperature compensation layer156can be an intervening layer between the conductive layer142and the grounding structure. In such cases, corresponding portions of the temperature compensation layer156can be etched and filled with the conductive material or the at least one via can be formed through the temperature compensation layer156and the piezoelectric layer142.

FIG.8Cis a cross sectional view of a portion of a surface acoustic wave resonator159with a multi-layer piezoelectric substrate according to another embodiment. The surface acoustic wave resonator159is like the surface acoustic wave resonator153ofFIG.8Aexcept that a temperature compensation layer156is included the surface acoustic wave resonator159. The surface acoustic wave resonator159can include a multi-layer piezoelectric substrate in accordance with any suitable principles and advantages disclosed herein. In some instances, the dispersion adjustment layer154and the temperature compensation156can be the same material. The dispersion adjustment layer154and the temperature compensation156can be different materials in certain instances.

The conductive layer158can be in electrical communication with a grounding structure positioned over the piezoelectric layer142in the surface acoustic wave resonator159. Alternatively or additionally, the conductive layer158can be in electrical communication with a grounding structure positioned under the carrier substrate152. In one aspect, the temperature compensation layer156, the piezoelectric layer142, and the dispersion adjustment layer154can be etched away or etched back at one or more edges of the surface acoustic wave resonator159. The etched away or etched back portions can be filled with conductive material such that the conductive material is in electrical communication with the grounding structure and the conductive layer158. In another aspect, at least one via can be formed through the temperature compensation layer156, the piezoelectric layer142, and the dispersion adjustment layer154of the surface acoustic wave resonator159such that conductive material filling the via provides electrical communication between the grounding structure and the conductive layer158.

An acoustic wave device can be manufactured in various manners. A method of manufacturing an acoustic wave device, according to an embodiment, includes providing an acoustic wave device structure. The acoustic wave structure includes a substrate, a conductive layer over the substrate, a piezoelectric layer over the conductive layer such that the conductive layer is positioned between the substrate and the piezoelectric layer, and an interdigital transducer electrode over the piezoelectric layer. The method also includes electrically connecting the conductive layer to a grounding structure that is positioned over the piezoelectric layer to thereby ground the conductive layer.

The method of manufacturing the acoustic wave device can include forming an opening through at least a portion of the piezoelectric layer to expose the conductive layer, and providing a conductive material in the opening. In some embodiments, the providing the conductive material can include forming a conductive material layer. The conductive material in the opening can provide the electrical connection between the conductive layer and the grounding structure. For example, the conductive material in the opening can define a filled via or a conformal via.

In certain embodiments, the method of manufacturing the acoustic wave device can include etching a portion of the piezoelectric layer and providing a conductive material in the etched portion of the piezoelectric layer. The conductive material in the etched portion can provide the electrical connection between the conductive layer and the grounding structure.

The method can include forming a temperature compensation layer over the interdigital transducer electrode in some embodiments.

The acoustic wave device structure can also include a dispersion adjustment layer positioned between the piezoelectric layer and the conductive layer in certain applications.

Any suitable principles and advantages disclosed herein can be implemented in any other type of acoustic wave resonator and/or acoustic wave device, such as a Lamb wave resonator or a boundary acoustic wave resonator. A Lamb wave resonator can include an IDT electrode on a piezoelectric layer and reflective gratings disposed on the piezoelectric layer on opposing sides of the IDT electrode. The reflective gratings can reflect acoustic waves induced by the IDT electrode to form a resonant cavity in such resonators. The reflective gratings can include a periodic pattern of metal on a piezoelectric layer. The Lamb wave resonators include a multi-layer piezoelectric substrate acoustic wave resonators in accordance with any suitable principles and advantages discussed herein.

FIGS.9A and9Bare flow charts illustrating processes to manufacture an acoustic wave resonator with a multi-layer piezoelectric substrate according to certain embodiments. The acoustic wave resonator can include a carrier substrate, a piezoelectric layer over the carrier substrate, a conductive layer between the piezoelectric layer and the carrier substrate, an IDT electrode over the piezoelectric layer, and a grounding structure configured to provide an electrical connection to ground positioned over the piezoelectric layer. In some aspects, the acoustic wave resonator can further include a dispersion adjustment layer positioned between the piezoelectric layer and the carrier substrate or a dispersion adjustment layer over the IDT electrode. In some aspects, the acoustic wave resonator can further include two dispersion adjustment layers where a first dispersion adjustment electrode is positioned between the piezoelectric layer and the carrier substrate and a second dispersion adjustment layer is positioned over the IDT electrode. In some aspects, the acoustic wave resonator can be any of acoustic wave resonators136,153,155, and159.

FIG.9Aillustrates a process to remove portions of layers between the conductive layer and the grounding structure to expose the conductive layer. The removed portions are filled in with a conductive material as illustrated, for example, in the acoustic wave resonator137ofFIG.4Band the acoustic wave resonator136ofFIG.4A.

At operation902, portions of at least the piezoelectric layer are removed to expose the conductive layer. In an aspect, corresponding portions of any intervening layers between the conductive layer and the grounding structure are also removed such that the conductive layer is exposed. Any suitable etching process can be used to remove the portions of the layer(s).

At operation904, the etched portions are filled in with a conductive material such that the conductive material is in electrical communication with the conductive layer. Any suitable deposition process can be used to deposit the conductive material in the etched portions. In an aspect, the fill-in portions extend above the piezoelectric layer to the grounding structure.

At operation906, the grounding structure is electrically connected to the filled-in conductive material such that the conductive layer is electrically connected to the grounding structure through the filled-in conductive material.

FIG.9Billustrates a process fabricate one or more vias between the conductive layer and the grounding structure. The one or more vias are filled with a conductive material as illustrated in the acoustic wave resonator138ofFIG.4C.

At operation912, a via is formed through at least the piezoelectric layer to expose the conductive layer. In an aspect, the via is formed through any intervening layers between the conductive layer and the grounding structure such that the conductive layer is exposed. For example, an opening is formed through the piezoelectric layer and any intervening layers to expose the conductive layer. Any suitable etching process can be used to form the opening.

At operation914, the opening is filled in with conductive material such that the conductive material is in electrical communication with the conductive layer. Any suitable deposition process can be used to deposit the conductive material in the opening. In an aspect, the via extends above the piezoelectric layer to the grounding structure.

At operation916, the grounding structure is electrically connected to the conductive material of the via such that the conductive layer is electrically connected to the grounding structure through the via.

While certain embodiments relate to acoustic wave devices with a grounding structure over a piezoelectric layer, a grounding structure can be positioned below a carrier substrate in some other embodiments. With a grounding structure positioned under the carrier substrate, one or more vias and/or other conductive structures extending through and/or along a sidewall of the carrier substrate can be included in an electrical path between a conductive layer and the grounding structure. Embodiments with a grounding structure on an opposite side of the carrier wafer than the conductive structure will be described with reference toFIGS.10A and10B.

FIG.10Ais a cross sectional view of a surface acoustic wave resonator170with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator170includes a carrier substrate152, a piezoelectric layer142over the carrier substrate152, an IDT electrode144over the piezoelectric layer142, a conductive layer158between the carrier substrate152and the piezoelectric layer142, and a dispersion adjustment layer154between the piezoelectric layer142and the conductive layer158. The surface acoustic resonator170also includes a grounding structure162cpositioned under the carrier substrate152. As illustrated, the grounding structure162cis on an opposite side of the carrier substrate152than the conductive layer158. The grounding structure162cis on an opposite side of the carrier substrate152than the piezoelectric layer142.

The grounding structure162cis electrically connected to the conductive layer158by way of a via166athrough the carrier substrate152. The grounding structure162ccan be electrically connected to the conductive layer158by two or more vias166a. The grounding structure162ccan have any structure and function of any of the grounding structures disclosed herein. For example, the grounding structure162ccan include one or more conductive pads. Alternatively, the grounding structure can include a conductive plate.

FIG.10Bis a cross sectional view of a surface acoustic wave resonator171with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator171can be generally similar to the surface acoustic wave resonator170illustrated inFIG.10A, except that a via166balso extends through the piezoelectric layer142and the dispersion adjustment layer154. The via166ais electrically connected with the IDT electrode144as illustrated. The via166bcan provide a ground connection to the IDT electrode144. The via166bcan be aligned with conductive material of the IDT electrode144as illustrated. This can provide a good electrical connection between the IDT electrode144and ground. As illustrated, a surface acoustic wave resonator can include both the via166aand the via166b.

FIG.10Cis a cross sectional view of a surface acoustic wave resonator173with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator173includes a carrier substrate152, a piezoelectric layer142over the carrier substrate152, an IDT electrode144over the piezoelectric layer142, a conductive layer158between the carrier substrate152and the piezoelectric layer142, and a dispersion adjustment layer154between the piezoelectric layer142and the conductive layer158. The surface acoustic resonator173also includes a grounding structure162cpositioned under the carrier substrate152. As illustrated, the grounding structure162cis on an opposite side of the carrier substrate152than the conductive layer158. The grounding structure162cis on an opposite side of the carrier substrate152than the piezoelectric layer142.

The grounding structure162cis electrically connected to the conductive layer158and the IDT electrode144by way of a conductive structure174. A portion of the conductive structure174is disposed along at least a portion of a sidewall of the acoustic wave resonator173. The conductive structure174can be conformably disposed along some or all of the sidewall of the acoustic wave resonator173. The conductive structure174can provide a ground connection to the IDT electrode174. In some other applications, the conductive structure174can provide a ground connection to one or more acoustic reflectors.

FIG.10Dis a cross sectional view of a surface acoustic wave resonator175with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator175is like the surface acoustic wave resonator173, except that the surface acoustic wave resonator175includes a conductive structure174that electrically connects the grounding structure162cto the conductive layer158and the IDT electrode144and a conductive structure176that electrically connects the grounding structure162cto the conductive layer158. In the surface acoustic wave resonator175, the conductive structures174and176extend along different sidewalls. The conductive structure174extends along more layers of the surface acoustic wave resonator175than the conductive structure176.

FIG.10Eis a cross sectional view of a surface acoustic wave resonator177with a multi-layer piezoelectric substrate according to an embodiment. The surface acoustic wave resonator177is like the surface acoustic wave resonator173, except that the surface acoustic wave resonator175includes a conductive structure174that electrically connects the grounding structure162cto the conductive layer158and the IDT electrode144and a via166athat extends through the carrier substrate152. In the surface acoustic wave resonator177, the conductive structure174extends along a single sidewall,

FIGS.10F and10Gare schematic diagrams of circuit topologies that include of surface acoustic wave resonators according to two embodiments. These circuit topologies illustrate a portion of a ladder filter that includes a series resonator182and a shunt resonator184. At least the shunt resonator184can be a multi-layer piezoelectric substrate surface acoustic wave resonator according to any embodiment disclosed herein. InFIG.10F, there is one ground connection to the conductive layer158. InFIG.10G, there are three ground connections to the conductive layer158. As illustrated, the ground connection(s) are connected to a conductive layer158. The conductive layer158is electrically connected between a shunt surface acoustic wave resonator184and ground inFIGS.10F and10G. As illustrated, a shunt inductance can be between each ground connection and ground. Accordingly, one shunt inductance is illustrated inFIG.10Fand three shunt inductances are illustrated inFIG.10G. In some embodiments, as compared to the shunt surface acoustic wave resonator illustrated inFIG.10F, the shunt surface acoustic wave resonator illustrated inFIG.10Gcan have a lower inductance associated with its connection to ground.

An acoustic wave device can be manufactured in various manners. A method of manufacturing an acoustic wave device, according to an embodiment, include providing an acoustic wave device structure. The acoustic wave device structure includes a substrate, a conductive layer over the substrate, a piezoelectric layer over the conductive layer such that the conductive layer is positioned between the substrate and the piezoelectric layer, and an interdigital transducer electrode over the piezoelectric layer. The method of manufacturing an acoustic wave device also includes electrically connecting the conductive layer to a grounding structure under the substrate. The substrate is positioned between the conductive layer and the grounding structure.

In some embodiments, the method can also include forming an opening through at least a portion of the substrate and providing a conductive material in the opening. The conductive material in the opening can provide electrical connection between the conductive layer and the grounding structure. The conductive material in the opening can define a via extending through the substrate.

In certain embodiments, the method of manufacturing an acoustic wave device can also include forming a temperature compensation layer over the interdigital transducer electrode.

The acoustic wave device structure can include a dispersion adjustment layer positioned between the piezoelectric layer and the conductive layer in some embodiments.

In certain embodiments, the grounding structure and the interdigital transducer electrode can be electrically connected by electrically connecting. In some such embodiments, after the electrically connecting, a first via extends from the grounding structure to the conductive structure and a second via extends from the grounding structure through the conductive layer to the interdigital transducer electrode. Therefore the electrically connecting can provide a ground connection to the conductive structure.

An acoustic wave device including any suitable combination of features disclosed herein can be included in a filter arranged to filter a radio frequency signal in a fifth generation (5G) New Radio (NR) operating band within Frequency Range 1 (FR1). A filter arranged to filter a radio frequency signal in a 5G NR operating band can include one or more SAW devices disclosed herein. FR1 can be from 410 MHz to 7.125 GHz, for example, as specified in a current 5G NR specification. An acoustic wave device with a grounded conductive layer in a multi-layer piezoelectric substrate can improve isolation between ports of an acoustic wave device that includes the acoustic wave device. Such improved isolation can be desirable for 5G NR applications.

One or more SAW devices in accordance with any suitable principles and advantages disclosed herein can be included in a filter arranged to filter a radio frequency signal in a 4G LTE operating band. One or more SAW devices in accordance with any suitable principles and advantages disclosed herein can be included in a filter arranged to filter a radio frequency signal in a filter having a passband that includes a 4G LTE operating band and a 5G NR operating band.

FIG.11is a schematic diagram of an example transmit filter180that includes acoustic wave resonators according to an embodiment. The transmit filter180can be a band pass filter. The illustrated transmit filter180is arranged to filter a radio frequency signal received at a transmit port TX and provide a filtered output signal to an antenna port ANT. The transmit filter180includes series SAW resonators TS1, TS2, TS3, TS4, TS5, TS6, and TS7, shunt SAW resonators TP1, TP2, TP3, TP4, and TP5, series input inductor L1, and shunt inductor L2. Some or all of the acoustic wave resonators TS1 to TS7 and/or TP1 to TP5 can be multi-layer piezoelectric substrate acoustic wave resonators in accordance with any suitable principles and advantages disclosed herein. Some or all of the acoustic wave resonators TS1 to TS7 and/or TP1 to TP5 can be surface acoustic wave resonators in accordance with any suitable principles and advantages disclosed herein. Any suitable number of series acoustic wave resonators and shunt acoustic wave resonators can be included in a transmit filter180. Such acoustic wave resonators can be surface acoustic wave resonators having a multi-layer piezoelectric substrate that includes a dispersion adjustment layer in accordance with any suitable principles and advantages disclosed herein.

FIG.12is a schematic diagram of a receive filter190that includes acoustic wave resonators according to an embodiment. The receive filter190can be a band pass filter. The illustrated receive filter190is arranged to filter a radio frequency signal received at an antenna port ANT and provide a filtered output signal to a receive port RX. The receive filter180includes series SAW resonators RS1, RS2, RS3, RS4, RS5, RS6, RS7, and RS8, shunt SAW resonators RP1, RP2, RP3, RP4, and RP5, and RP6, shunt inductor L2, and series output inductor L3. Some or all of the acoustic wave resonators RS1 to RS8 and/or RP1 to RP6 can be multi-layer piezoelectric substrate acoustic wave resonators in accordance with any suitable principles and advantages disclosed herein. Some or all of the acoustic wave resonators RS1 to RS8 and/or RP1 to RP6 can be surface acoustic wave in accordance with any suitable principles and advantages disclosed herein. Any suitable number of series acoustic wave resonators and shunt acoustic wave resonators can be included in a receive filter190. Such acoustic wave resonators can be surface acoustic wave resonators having a multi-layer piezoelectric substrate that includes a dispersion adjustment layer in accordance with any suitable principles and advantages disclosed herein.

FIG.13is a schematic diagram of a radio frequency module200that includes an acoustic wave component202according to an embodiment. The illustrated radio frequency module200includes the acoustic wave component202and other circuitry203. The acoustic wave component202can include one or more multi-layer piezoelectric substrate acoustic wave resonators with any suitable combination of features of the acoustic wave resonators disclosed herein. The acoustic wave component202can include an acoustic wave die that includes acoustic wave resonators. For example, the acoustic wave component202can include a SAW die that includes SAW resonators.

The acoustic wave component202shown inFIG.13includes a filter204and terminals205A and205B. The filter204includes acoustic wave resonators. One or more of the acoustic wave resonators can be implemented in accordance with any suitable principles and advantages of the multi-layer piezoelectric substrate acoustic wave resonators disclosed herein. The terminals205A and205B can serve, for example, as an input contact and an output contact. The acoustic wave component202and the other circuitry203are on a common packaging substrate206inFIG.13. The package substrate206can be a laminate substrate. The terminals205A and205B can be electrically connected to contacts207A and207B, respectively, on the packaging substrate206by way of electrical connectors208A and208B, respectively. The electrical connectors208A and208B can be bumps or wire bonds, for example.

The other circuitry203can include any suitable additional circuitry. For example, the other circuitry can include one or more power amplifiers, one or more radio frequency switches, one or more additional filters, one or more low noise amplifiers, one or more RF couplers, one or more delay lines, one or more phase shifters, the like, or any suitable combination thereof. The radio frequency module200can include one or more packaging structures to, for example, provide protection and/or facilitate easier handling of the radio frequency module200. Such a packaging structure can include an overmold structure formed over the packaging substrate200. The overmold structure can encapsulate some or all of the components of the radio frequency module200.

FIG.14is a schematic diagram of a radio frequency module210that includes an acoustic wave component according to an embodiment. As illustrated, the radio frequency module210includes duplexers212A to212N that include respective transmit filters213A1to213N1and respective receive filters213A2to213N2, a power amplifier214, a select switch215, and an antenna switch216. The radio frequency module210can include a package that encloses the illustrated elements. The illustrated elements can be disposed on a common packaging substrate206. The packaging substrate206can be a laminate substrate, for example. A radio frequency module that includes a power amplifier can be referred to as a power amplifier module. A radio frequency module can include a subset of the elements illustrated inFIG.14and/or additional elements.

The duplexers212A to212N can each include two acoustic wave filters coupled to a common node. The two acoustic wave filters can be a transmit filter and a receive filter. As illustrated, the transmit filter and the receive filter can each be a band pass filter arranged to filter a radio frequency signal. One or more of the transmit filters213A1to213N1can include one or more multi-layer piezoelectric substrate acoustic wave resonators in accordance with any suitable principles and advantages disclosed herein. Similarly, one or more of the receive filters213A2to213N2can include one or more multi-layer piezoelectric substrate acoustic wave resonators in accordance with any suitable principles and advantages disclosed herein. AlthoughFIG.14illustrates duplexers, any suitable principles and advantages disclosed herein can be implemented in other multiplexers (e.g., quadplexers, hexaplexers, octoplexers, etc.) and/or in switch-plexers.

The power amplifier214can amplify a radio frequency signal. The illustrated switch215is a multi-throw radio frequency switch. The switch215can electrically couple an output of the power amplifier214to a selected transmit filter of the transmit filters213A1to213N1. In some instances, the switch215can electrically connect the output of the power amplifier214to more than one of the transmit filters213A1to213N1. The antenna switch216can selectively couple a signal from one or more of the duplexers212A to212N to an antenna port ANT. The duplexers212A to212N can be associated with different frequency bands and/or different modes of operation (e.g., different power modes, different signaling modes, etc.).

FIG.15Ais a schematic diagram of a wireless communication220device that includes filters223in a radio frequency front end222according to an embodiment. The filters223can include one or more multi-layer piezoelectric substrate acoustic wave resonators in accordance with any suitable principles and advantages discussed herein. The wireless communication device220can be any suitable wireless communication device. For instance, a wireless communication device220can be a mobile phone, such as a smart phone. As illustrated, the wireless communication device220includes an antenna221, an RF front end222, a transceiver224, a processor225, a memory226, and a user interface227. The antenna221can transmit RF signals provided by the RF front end222. Such RF signals can include carrier aggregation signals. The antenna221can receive RF signals and provide the received RF signals to the RF front end222for processing.

The RF front end222can include one or more power amplifiers, one or more low noise amplifiers, one or more RF switches, one or more receive filters, one or more transmit filters, one or more duplex filters, one or more multiplexers, one or more frequency multiplexing circuits, the like, or any suitable combination thereof. The RF front end222can transmit and receive RF signals associated with any suitable communication standards. The filters223can include one or more multi-layer piezoelectric substrate acoustic wave resonators that include any suitable combination of features discussed with reference to any embodiments discussed above.

The transceiver224can provide RF signals to the RF front end222for amplification and/or other processing. The transceiver224can also process an RF signal provided by a low noise amplifier of the RF front end222. The transceiver224is in communication with the processor225. The processor225can be a baseband processor. The processor225can provide any suitable base band processing functions for the wireless communication device220. The memory226can be accessed by the processor225. The memory226can store any suitable data for the wireless communication device220. The user interface227can be any suitable user interface, such as a display with touch screen capabilities.

FIG.15Bis a schematic diagram of a wireless communication device230that includes filters223in a radio frequency front end222and second filters233in a diversity receive module232. The wireless communication device230is like the wireless communication device220ofFIG.15A, except that the wireless communication device230also includes diversity receive features. As illustrated inFIG.15B, the wireless communication device230includes a diversity antenna231, a diversity module232configured to process signals received by the diversity antenna231and including filters233, and a transceiver234in communication with both the radio frequency front end222and the diversity receive module232. The filters233can include one or more multi-layer piezoelectric substrate acoustic wave resonators that include any suitable combination of features discussed with reference to any embodiments discussed above.

Although embodiments are discussed with reference to certain acoustic wave resonators, any suitable principles and advantages disclosed herein can be applied to any other suitable acoustic wave resonators, such as boundary acoustic wave resonators or Lamb wave resonators.

Any of the embodiments described above can be implemented in mobile devices such as cellular handsets. The principles and advantages of the embodiments can be used for any systems or apparatus, such as any uplink cellular device, that could benefit from any of the embodiments described herein. The teachings herein are applicable to a variety of systems. Although this disclosure includes some example embodiments, the teachings described herein can be applied to a variety of structures. Any of the principles and advantages discussed herein can be implemented in association with RF circuits configured to process signals having a frequency in a range from about 30 kHz to 300 GHz, such as a frequency in a range from about 450 MHz to 8.5 GHz.

Aspects of this disclosure can be implemented in various electronic devices. Examples of the electronic devices can include, but are not limited to, consumer electronic products, parts of the consumer electronic products such as die and/or acoustic wave filter assemblies and/or packaged radio frequency modules, uplink wireless communication devices, wireless communication infrastructure, electronic test equipment, etc. Examples of the electronic devices can include, but are not limited to, a mobile phone such as a smart phone, a wearable computing device such as a smart watch or an ear piece, a telephone, a television, a computer monitor, a computer, a modem, a hand-held computer, a laptop computer, a tablet computer, a personal digital assistant (PDA), a microwave, a refrigerator, an automobile, a stereo system, a DVD player, a CD player, a digital music player such as an MP3 player, a radio, a camcorder, a camera, a digital camera, a portable memory chip, a washer, a dryer, a washer/dryer, a peripheral device, a wrist watch, a clock, etc. Further, the electronic devices can include unfinished products.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” “include,” “including” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” The word “coupled”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Likewise, the word “connected”, as generally used herein, refers to two or more elements that may be either directly connected, or connected by way of one or more intermediate elements. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or” in reference to a list of two or more items, that word covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

Moreover, conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” “for example,” “such as” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel apparatus, methods, and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure. For example, while blocks are presented in a given arrangement, alternative embodiments may perform similar functionalities with different components and/or circuit topologies, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these blocks may be implemented in a variety of different ways. Any suitable combination of the elements and acts of the various embodiments described above can be combined to provide further embodiments. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosure.