Acoustic wave device with acoustically separated multi-channel feedback

Aspects of this disclosure relate to an acoustic wave device that includes an acoustic obstacle disposed between canceling circuits coupled to one or more acoustic wave filters. The canceling circuits can cancel frequency components within different frequency bands. The acoustic obstacle can reduce acoustic coupling between the canceling circuits by scattering and/or absorbing acoustic energy.

BACKGROUND

Technical Field

Embodiments of this disclosure relate to acoustic wave filters.

Description of Related Technology

An acoustic wave filter can include a plurality of resonators arranged to filter a radio frequency signal. Example acoustic wave filters include surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters. A film bulk acoustic resonator (FBAR) filter is an example of a BAW filter.

Acoustic wave filters can be implemented in radio frequency electronic systems. For instance, filters in a radio frequency front end of a mobile phone can include acoustic wave filters. Two acoustic wave filters can be arranged as a duplexer.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One aspect of this disclosure is an acoustic wave device that includes a first canceling circuit, a second canceling circuit, an acoustic wave filter, and an acoustic obstacle. The first canceling circuit is arranged to cancel frequency components in a first frequency band. The second canceling circuit is arranged to cancel frequency components within a second frequency band. The acoustic wave filter is coupled to the first canceling circuit and the second canceling circuit. The acoustic obstacle is disposed between the first canceling circuit and the second canceling circuit.

The acoustic obstacle can be arranged to absorb acoustic energy. The acoustic obstacle can include a polymer. The acoustic wave device can include a cavity wall including the same polymer as the acoustic obstacle.

The acoustic obstacle can be arranged to scatter acoustic energy. The acoustic wave filter can include a surface acoustic wave resonator and the first canceling circuit can include an interdigital transducer electrode. The acoustic obstacle and the interdigital transducer electrode can each include the same material. The acoustic obstacle can have a zig-zag shape. The acoustic obstacle can to absorb acoustic energy and to scatter acoustic energy in certain embodiments.

The acoustic wave device can include a second acoustic wave filter coupled to the first canceling circuit and the second canceling circuit. The first acoustic wave filter can be a transmit filter and the second acoustic wave filter can be a receive filter. The first canceling circuit can attenuate a transmission characteristic of the receive filter at frequencies in a pass band of the transmit filter. The first acoustic wave filter and the second acoustic wave filter can be coupled to each other at a common antenna node. The first acoustic wave filter and the second acoustic wave filter can be included in a duplexer.

Another aspect of this disclosure is a multiplexer that includes a transmit filter, a receive filter, a first canceling circuit, a second canceling circuit, and an acoustic obstacle. The transmit filter includes first acoustic wave resonators. The receive filter includes second acoustic wave resonators. The receive filter and the transmit filter are coupled to each other at a common node. The first canceling circuit is coupled to the transmit filter and to the receive filter. The second canceling circuit is coupled to the transmit filter and to the receive filter. The acoustic obstacle is disposed between the first canceling circuit and the second canceling circuit.

The first canceling circuit can attenuate a transmission characteristic of the receive filter at frequencies in a pass band of the transmit filter. The first canceling circuit and the second canceling circuit can cancel frequency components of different carriers of a carrier aggregation signal. The second canceling circuit can attenuate a transmission characteristic of the transmit filter at frequencies in a pass band of the receive filter.

The multiplexer can be a duplexer. The common node can be an antenna node of the multiplexer.

The acoustic obstacle can be arranged to absorb acoustic energy. Alternatively or additionally, the acoustic obstacle can be arranged to scatter acoustic energy.

The first canceling circuit can include an interdigital transducer electrode. The acoustic obstacle and the interdigital transducer electrode can each include the same material.

Another aspect of this disclosure is a surface acoustic wave device that includes a surface acoustic wave filter and a multi-channel feedback circuit coupled to the surface acoustic wave filter. The multi-channel feedback circuit includes first interdigital transducer electrodes corresponding to a first channel, second interdigital transducer electrodes corresponding to a second channel, and an acoustic obstacle arranged to reduce acoustic coupling between the first interdigital transducer electrodes and the second interdigital transducer electrodes.

The surface acoustic wave device can include a cavity wall. The acoustic obstacle can include the same material as the cavity wall.

The acoustic obstacle and the first interdigital transducer electrodes both include the same material. In some instances, the acoustic obstacle can also include a polymer.

The acoustic obstacle can absorb acoustic energy. Alternatively or additionally, the acoustic obstacle can scatter energy.

The surface acoustic wave device can further include a second surface acoustic wave filter coupled to the multi-channel feedback circuit. The first acoustic wave device can be a transmit filter and the second acoustic wave device can be a receive filter. The first acoustic wave filter and the second acoustic wave filter can be coupled to each other at a common node. The first acoustic wave filter and the second acoustic wave filter can be included in a duplexer. The first acoustic wave filter can be arranged to filter radio frequency signals.

In some instances, the first channel and the second channel can correspond to different respective carriers of a carrier aggregation signal. In some instances, the first channel can correspond to a transmit channel and the second channel can correspond to a receive channel.

Another aspect of this disclosure is a method of manufacturing an acoustic wave device. The method includes forming an acoustic obstacle between canceling circuits coupled to an acoustic wave filter such that the acoustic obstacle is arranged to reduce acoustic coupling between the canceling circuits. The canceling circuits are associated with different frequency bands.

The acoustic wave device can be a surface acoustic wave device. The canceling circuits can include interdigital transducer electrodes. Forming the acoustic obstacle can include patterning the same material as the interdigital transducer electrodes during a processing operation to form the interdigital transducer electrodes.

The acoustic obstacle can include a polymer. The polymer of can be formed while a cavity wall of the acoustic wave device is being formed of the same polymer.

The method can include electrically connecting the canceling circuits to the acoustic wave filter and a second acoustic wave filter. The frequency band can correspond to a pass band of the second acoustic wave filter. The method can include arranging the first acoustic wave filter and the second acoustic wave filter as a duplexer.

Another aspect of this disclosure is a method of filtering a radio frequency signal. The method includes providing, using an acoustic obstacle, acoustic separation between a canceling circuit and another canceling circuit positioned in proximity to the canceling circuit; applying a signal to an acoustic wave filter using the canceling circuit so as to attenuate a transmission characteristic of the acoustic wave filter within a frequency band outside the pass band of the acoustic wave filter; and filtering a radio frequency signal with the acoustic wave filter with the attenuated transmission characteristic.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

Some mobile applications are specifying for filters and/or duplexers to achieve higher rejection performance in several rejection frequency bands. To achieve relatively high rejection, a feedback circuit can be implemented. A feedback circuit can include interdigital transducers (IDTs) and transmission lines. The interdigital transducers can control magnitude and phase of a signal. Transmission lines can be connected to a main filter circuit to cancel a portion of the main filter response.

To avoid the communication between IDTs of feedback circuits, such IDTs can be implemented with physical layouts that are relatively far away from each other. However, the desire to minimize a filter die size can restrict options for designers to physically lay out IDTs of feedback circuits. In some instances, it is not possible to have IDTs of different feedback circuits with physical layouts sufficiently far away from each other to avoid communication between the IDTs of the different feedback circuits. Aspects of this disclosure relate to including an acoustic obstacle between IDTs of different feedback circuits to prevent acoustic communication between the IDTs of different feedback circuits. This can allow designers more flexibility in the physical layout of the feedback circuits.

To improve multi-frequency band rejection, several IDTs of feedback circuits for each rejection band can be implemented. IDTs of different feedback circuits can communicate with each other by acoustic coupling. Accordingly, an unwanted response can be excited and degrade the rejection performance of a filter. To overcome this problem, an acoustic obstacle can be positioned between IDTs of different feedback circuits for different rejection bands. The acoustic obstacle can be made of the same material as an IDT. Alternatively or additionally, the acoustic obstacle can include a polymer. The same polymer material can form an air cavity of an acoustic wave filter and/or a duplexer. The acoustic obstacle can be formed as part of a front end process and/or a back end process.

Acoustic obstacles can be disposed between different canceling circuits arranged to cancel frequency components within different frequency bands. Such acoustic obstacles can be implemented in an acoustic wave device that includes an acoustic wave filter coupled to the canceling circuits. The acoustic wave filter can be a surface acoustic wave filter. In some embodiments, the different canceling circuits can be coupled to both a transmit filter that includes first acoustic wave resonators and a receive filter that includes second acoustic wave resonators, in which the transmit filter and the receive filter are coupled to each other at a common node. According to certain embodiments, a surface acoustic wave device includes a surface acoustic wave filter, a multi-channel feedback circuit coupled to the surface acoustic wave filter, and an acoustic obstacle disposed between interdigital transducer electrodes of the multi-channel feedback circuit.

FIG. 1Ais a schematic diagram of an acoustic wave device10that includes a first filter11, a second filter12, and a multi-channel feedback circuit. The acoustic wave device10ofFIG. 1Ais arranged as a duplexer having a transmit port Tx, a receive port Rx, and an antenna port ANT. While embodiments discussed herein may relate to duplexers, any suitable principle and advantages discussed herein can be applied to other types of multiplexers, such as quadplexers, hexaplexers, etc. Moreover, any suitable principle and advantages can be implemented in association with a single filter and/or a plurality of filters.

As illustrated inFIG. 1A, the multi-channel feedback circuit includes a first canceling circuit14and a second canceling circuit15. These canceling circuits can cancel frequency components within different frequency bands or channels. The first canceling circuit14and the second canceling circuit15ofFIG. 1Acan communicate with each other by acoustic coupling. This can result in an unwanted frequency response that degrades the rejection performance of the first filter11and/or the second filter12.

FIG. 1Bis a schematic diagram of an acoustic wave device20according to an embodiment. The acoustic wave device20ofFIG. 1Ais arranged as a duplexer. The acoustic wave device20includes a multi-channel feedback circuit with acoustically separated multi-channel feedback. The acoustic wave device20is like the acoustic wave device10ofFIG. 1A, except that an acoustic obstacle18is also included in the acoustic wave device20ofFIG. 1B. As shown inFIG. 1B, an acoustic obstacle18can be disposed between the first canceling circuit14and the second canceling circuit15. The acoustic obstacle18can include a metal pattern, a cavity pillar, a silicon dioxide grove, any other suitable obstacle, or any suitable combination thereof. The acoustic obstacle18can reduce and/or eliminate acoustic coupling between the first canceling circuit14and the second canceling circuit15. The acoustic obstacle18can absorb and/or scatter acoustic energy.

As illustrated inFIG. 1B, the first canceling circuit14and the second canceling circuit15are both coupled to the first filter11. Similarly, the first canceling circuit14and the second canceling circuit15are both coupled to the second filter12inFIG. 1B. The canceling circuits14and15can cancel signal components in respective frequency bands by reducing and/or eliminating such signal components. The canceling circuits14and15can each apply a signal having an opposite phase as an unwanted signal component to reduce and/or eliminate the effect of such an unwanted signal component. These canceling circuits can cancel frequency components within different frequency bands or channels. For instance, the first canceling circuit14can cancel frequency components within a first channel and the second canceling circuit15can cancel frequency components within a second channel, in which the first channel and second channel are different frequency bands. This can provide higher rejection in the first channel and the second channel.

The first channel can correspond to a lower rejection band and the second channel can correspond to a higher rejection band. In some instances, the first channel and the second channel can be associated with different carriers of a carrier aggregation signal. The first canceling circuit14and the second canceling circuit15can cancel frequency components in different bands of the second filter12in certain instances. The first canceling circuit14and the second canceling circuit15can cancel frequency components in different bands of the first filter11in certain instances.

According to some instances, the first canceling circuit14can cancel frequency within the first channel in the frequency response of the second filter12and the second canceling circuit15can cancel frequency components within the second channel in the frequency response of the first filter11. In an example, the first channel can correspond to a transmit channel and the first canceling circuit14can cancel noise associated with the first channel in the response of the second filter12. Accordingly, the first canceling circuit14can attenuate a transmission characteristic of the receive filter12at frequencies in a pass band of the transmit filter11. In some such instances, the second channel can correspond to a receive channel and the second canceling circuit15can cancel noise associated with the second channel in the response of the first filter11. Accordingly, the second canceling circuit15can attenuate a transmission characteristic of the transmit filter11at frequencies in a pass band of the receive filter12.

The canceling circuits14and15can include interdigital transducer electrodes as illustrated. In such canceling circuits, the IDT electrodes can apply a signal having approximately the same amplitude and an opposite phase to a signal component to be canceled. In some other instances, the first canceling circuit and/or the second canceling circuit can include bulk acoustic wave element(s) and/or an LC circuit. As shown inFIG. 1B, the IDTs of the canceling circuits14and15can be coupled to the first filter11by way of a first capacitor16and other IDTs of the canceling circuits14and15can be coupled to the second filter12by way of a second capacitor17. Any suitable principles and advantages of an acoustically separated multi-channel feedback circuit discussed herein can be implemented in association with a multi-channel feedback circuit arranged in parallel with a filter. The first canceling circuit14and/or the second canceling circuit15can be implemented in accordance with any suitable principles and advantages described in U.S. Pat. No. 9,246,533 and/or U.S. Pat. No. 9,520,857, the disclosures of these patents are hereby incorporated by reference in their entireties herein.

The first filter11is arranged to filter a radio frequency signal. A radio frequency signal can have a frequency in a range from 30 kHz to 300 GHz, such as in a range from about 450 MHz to 6 GHz. The first filter11can include acoustic wave resonators. For instance, the first filter can include surface acoustic wave resonators. As another example, the first filter can alternatively or additionally include one or more BAW resonators, such as FBARs. The first filter11can be a ladder filter that includes series acoustic wave resonators and shunt acoustic wave resonators. As illustrated, the first filter11is a transmit filter. The illustrated second filter12is a receive filter. The second filter12can be implemented in accordance with any suitable principles and advantages discussed with reference to the first filter11.

FIG. 1Cis a graph of transmit-receive isolation for the duplexers ofFIGS. 1A and 1B.FIG. 1Cindicates that the acoustic obstacle18ofFIG. 1Bimproves rejection in channel1and also improves rejection in channel2.

FIGS. 1D to 1Kare schematic diagrams of acoustic wave devices that include an acoustic obstacle between canceling circuits for different frequency bands according to certain embodiments. Any suitable principles and advantages of these acoustic wave devices can be implemented with each other and/or with the acoustic wave device ofFIG. 1B.

FIG. 1Dis a schematic diagram of an acoustic wave device22that includes a feedback circuit with acoustically separated multi-channel feedback according to an embodiment. As shown inFIG. 1D, the second canceling circuit15′ can include fewer IDT electrodes than the second canceling circuit15illustrated inFIG. 1B. More generally, any of the canceling circuits of a multi-channel feedback circuit can include any suitable number of IDT electrodes.

FIG. 1Eis a schematic diagram of an acoustic wave device24that includes a feedback circuit with acoustically separated multi-channel feedback according to an embodiment.FIG. 1Eillustrates that more than one acoustic obstacle can be included between canceling circuits of a multi-channel feedback circuit. As shown inFIG. 1E, the multi-channel feedback circuit includes a first canceling circuit14, a second canceling circuit15′, and a third canceling circuit25. A first acoustic obstacle18is disposed between the first canceling circuit14and the second canceling circuit15′. A second acoustic obstacle26is disposed between the second canceling circuit15′ and the third canceling circuit25.FIG. 1Ealso illustrates that more than two canceling circuits can be implemented in a multi-channel feedback circuit. Accordingly, in certain embodiments, a multi-channel feedback circuit can include three or more canceling circuits and two or more acoustic obstacles.

FIG. 1Fis a schematic diagram of an acoustic wave device27that includes a feedback circuit with acoustically separated multi-channel feedback according to an embodiment.FIG. 1Fillustrates that positions of the canceling circuits of a multi-channel feedback circuit can be offset from each other. As shown inFIG. 1F, the first canceling circuit14is offset from the third canceling circuit25. This schematic representation of canceling circuits being offset from each other can correspond to physical offsets in layout of IDTs of the canceling circuits. Offsetting IDT tracks of different canceling circuits from each other combined with including an acoustic obstacle between the different canceling circuits can reduce acoustic coupling between IDTs of the canceling circuits and improve performance of the canceling circuits.

FIG. 1Gis a schematic diagram of an acoustic wave device28that includes a feedback circuit with acoustically separated multi-channel feedback according to an embodiment.FIG. 1Gillustrates that IDTs of a canceling circuit can be disposed between reflective gratings. As illustrated, a reflective grating29ais disposed between an IDT of the first canceling circuit14and the acoustic obstacle18. Similarly, a reflective grating29bcan be disposed between an IDT of the second canceling circuit15′ and the acoustic obstacle18. The first canceling circuit14is disposed between reflective gratings29aand29cinFIG. 1G. Similarly, the second canceling circuit15′ can be disposed between reflective gratings29band29d.

While multi-channel feedback circuits can be coupled between a transmit port and a receive port of a duplexer, a multi-channel feedback circuit can be coupled to filter at a different point than a transmit port or a receive port. For instance, a multi-channel feedback circuit can be coupled to a node between two series resonators in an acoustic wave filter. In the acoustic wave device30ofFIG. 1H, a multi-channel feedback circuit is coupled to the second filter12at a node between the receive port Rx and the antenna port ANT. In the acoustic wave device32ofFIG. 1I, a multi-channel feedback circuit is coupled to the first filter11at a node between the transmit port Tx and the antenna port ANT. In other instances, a multi-channel feedback circuit can be coupled to the first filter11at a node between the transmit port Tx and the antenna port ANT and also coupled to the second filter12at a node between the receive port Tx and the antenna port ANT.

In some embodiments, a multi-channel feedback circuit can receive feedback from more than two nodes in an electronic system.FIG. 1Jis a schematic diagram of an acoustic wave device35that includes a multi-channel feedback circuit coupled to more than two nodes of the acoustic wave device35according to an embodiment. The illustrated multi-channel feedback circuit includes a first canceling circuit36and a second canceling circuit37. Each of these canceling circuits is coupled to a transmit port Tx, a receive port Rx, and an antenna port ANT. The first canceling circuit36is similar to the first canceling circuit14discussed above except that an additional IDT electrode is coupled to the antenna port ANT by way of a capacitor38. The canceling circuit36can operate as a Double Mode SAW filter. The second canceling circuit37is similar to the second canceling circuit15′ discussed above except that an additional IDT electrode is coupled to the antenna port ANT by way of a capacitor38. The canceling circuit37can operate as a Double Mode SAW filter. The illustrated acoustic obstacle18is disposed between the first canceling circuit36and the second canceling circuit37to absorb and/or scatter acoustic energy.

Although various multi-channel feedback circuits discussed herein are coupled between a transmit port and a receive port of a duplexer, any suitable principles and advantages discussed herein can be implemented in other contexts. For instance, a multi-channel feedback circuit can be coupled between two nodes of a filter. As an example, a multi-channel feedback circuit can be coupled in parallel with a filter.FIG. 1Kis a schematic diagram of an acoustic wave device40that includes a multi-channel feedback circuit coupled in parallel with a filter42according to an embodiment. The filter42is a ladder filter that includes series resonators and shunt resonators. The first filter11and/or the second filter12can be implemented in accordance with any suitable principles and advantages of the filter42. The filter42can be a transmit filter in some instances, in which an input port IN is a transmit port and an output port OUT is an antenna port. In some other instances (not shown inFIG. 1K), the first feedback circuit14and/or the second feedback circuit15′ can be coupled to a node between two series resonators of the filter42.

FIGS. 2A to 2Cillustrate views of acoustic wave devices that include an acoustic obstacle between canceling circuits for different frequency bands according to certain embodiments. Any suitable principles and advantages of these acoustic wave devices can be implemented with each other and/or in combination with any of the other acoustic wave devices discussed herein.

FIG. 2Aillustrates a first view50and a second view55of an acoustic wave device according to an embodiment. InFIG. 2A, the acoustic wave device includes an acoustic obstacle52, IDT electrodes53A and53B of a first canceling circuit, IDT electrodes53C and53D of a second canceling circuit, and a piezoelectric substrate54on which the acoustic obstacle52and the IDT electrodes53A to53D are positioned. The acoustic obstacle52is disposed between IDT electrodes53B and53C to reduce and/or eliminate acoustic coupling between the first canceling circuit and the second canceling circuit. The acoustic obstacle52can be formed of the same material as an IDT electrode of a canceling circuit. The acoustic obstacle52can have any suitable shape. For instance, the acoustic obstacle52can have a zig-zag shape as illustrated. The acoustic obstacle52ofFIG. 2Acan scatter and/or diffract acoustic energy.

FIG. 2Billustrates a first view60and a second view65of an acoustic wave device according to an embodiment. InFIG. 2B, the acoustic wave device includes an acoustic obstacle62configured to absorb acoustic energy. The acoustic obstacle62can be formed of the same material as a cavity wall64A and/or64B of the acoustic wave device. The acoustic obstacle62can be a polymer pillar between IDT electrodes of different canceling circuits. The acoustic wave device illustrated inFIG. 2Balso includes a roof66over the IDT electrodes53A to53D and the acoustic obstacle62. The roof66can be separated by the acoustic obstacle62by a gap. The roof66can be formed of the same material(s) as the cavity walls64A and64B and the acoustic obstacle62.

FIG. 2Cillustrates a first view70and a second view75of an acoustic wave device according to another embodiment. This drawing illustrates that an acoustic obstacle72can include the features of the acoustic obstacle52ofFIG. 2Acombined with the acoustic obstacle62ofFIG. 2B. The acoustic obstacle72can absorb and scatter acoustic energy.

FIGS. 3A to 4illustrate views of acoustic wave devices that include an acoustic obstacle between canceling circuits for different frequency bands according to certain embodiments. These acoustic wave devices include a dielectric layer, such as silicon dioxide layer, over IDT electrodes. The dielectric layer can be a temperature compensating layer. The temperature compensating layer can bring the temperature coefficient of frequency (TCF) of an acoustic wave device closer to zero. A TCF of close to zero is generally desirable. The temperature compensating layer can have a positive temperature coefficient of frequency. A non-dielectric temperature compensating layer can be implemented in place of a dielectric layer in any of the acoustic wave devices ofFIG. 3A, 3B, 3C, or4. Any suitable principles and advantages of these acoustic wave devices can be implemented with each other and/or in combination with any of the other acoustic wave devices discussed herein.

FIG. 3Aillustrates a first view80and a second view83of an acoustic wave device according to an embodiment. The acoustic wave device ofFIG. 3Ais like the acoustic wave device ofFIG. 2Aexcept that the acoustic wave device ofFIG. 3Aincludes a dielectric layer82over the IDT electrodes53A to53D and the acoustic obstacle52. The dielectric layer82can be a silicon dioxide layer.FIG. 3Aillustrates that an acoustic wave device can include an acoustic obstacle52that includes a pattern of the same material as an IDT electrode53A to53D and that the acoustic obstacle52can be covered by the dielectric layer82. The acoustic obstacle52can scatter acoustic energy. This can reduce and/or eliminate acoustic coupling between a first canceling circuit that includes IDT electrodes53A and53B and a second canceling circuit that includes IDT electrodes53C and53D.

FIG. 3Billustrates a first view84and a second view85of an acoustic wave device according to an embodiment. The acoustic wave device ofFIG. 3Bis like the acoustic wave device ofFIG. 2Bexcept that the acoustic wave device ofFIG. 3Bincludes a dielectric layer82. The dielectric layer82is over the IDT electrodes53A to53D. InFIG. 3B, the dielectric layer82is disposed between the acoustic obstacle62and the piezoelectric substrate54. As shown inFIG. 3B, the acoustic obstacle62can include a polymer pillar over the dielectric layer82.

FIG. 3Cillustrates a first view87and a second view89of an acoustic wave device according to an embodiment. The acoustic wave device ofFIG. 3Cincludes an acoustic obstacle72′ that includes a combination of the acoustic obstacle52ofFIG. 3Aand the acoustic obstacle62ofFIG. 3B. As shown inFIG. 3C, the acoustic obstacle72′ can include (1) patterned material that is the same material as an IDT electrode and covered by a dielectric layer82, and (2) a polymer pillar over the dielectric layer82.

FIG. 3Dillustrates a first view90and a second view92of an acoustic wave device according to an embodiment. The acoustic wave device ofFIG. 3Dis like the acoustic wave device ofFIG. 3Bexcept that the acoustic wave device ofFIG. 3Dincludes an acoustic obstacle62in contact with the piezoelectric substrate54. InFIG. 3D, the dielectric layer82is not included between the acoustic obstacle62and the piezoelectric substrate54. As shown inFIG. 3D, the acoustic obstacle62can include a polymer pillar disposed between IDT electrodes53B and53C of different canceling circuits that are covered by a dielectric layer82. Without dielectric layer82under the polymer pillar, adhesion of the polymer pillar can be improved relative to a polymer pillar over a dielectric layer the in certain applications.

FIG. 3Eillustrates a first view94and a second view96of an acoustic wave device according to another embodiment. The acoustic wave device ofFIG. 3Eincludes an acoustic obstacle72that includes a combination of the acoustic obstacle52ofFIG. 3Aand the acoustic obstacle62ofFIG. 3D. As shown inFIG. 3E, the acoustic obstacle72can include (1) patterned material that is the same material as an IDT electrode, and (2) a polymer pillar over the patterned material. Similar to the acoustic obstacle62ofFIG. 3D, without a dielectric material under the polymer pillar, adhesion of the polymer pillar of the acoustic obstacle72can be improved relative to the acoustic obstacle72′ ofFIG. 3Cin certain applications.

While the acoustic obstacles ofFIGS. 3A to 3Eare separated from roof66of a cavity, the acoustic obstacle can be connected to the roof66of the cavity in certain instances.FIG. 4illustrates a first view100and a second view102of an acoustic wave device in which an acoustic obstacle72″ is connected to a roof66of a cavity. The acoustic obstacle72″ can include a polymer pillar in contact with the roof66of the cavity. The acoustic wave device ofFIG. 4is like the acoustic wave device ofFIG. 3Eexcept that the acoustic obstacle72ofFIG. 3Eis separated from the cavity roof66.

Acoustic wave devices can be manufactured in accordance with any suitable principles and advantages discussed herein. In such methods of manufacture, an acoustic obstacle can be formed between canceling circuits coupled to an acoustic wave filter such that the acoustic obstacle is arranged to reduce acoustic coupling between the canceling circuits associated with different frequency bands. In some such methods in which the canceling circuits include interdigital transducer electrodes, forming the acoustic obstacle can include patterning the same material as the interdigital transducer electrodes during a processing operation to form the interdigital transducer electrodes. Alternatively or additionally, in certain methods of manufacture, the acoustic obstacle can include a polymer and forming the acoustic obstacle can include forming the polymer of the acoustic obstacle while at least a portion of the cavity wall of the acoustic wave device is being formed of the same polymer. Methods of manufacture can further include electrically connecting the canceling circuits to the acoustic wave filter and a second acoustic wave filter and/or arranging the first acoustic wave filter and the second acoustic wave filter as a duplexer.

Moreover, radio frequency signals can be filtered using any suitable principles and advantages of the acoustic wave devices discussed herein. A method of filtering a radio frequency signal can include providing, using an acoustic obstacle, acoustic separation between a canceling circuit and another canceling circuit positioned in proximity to the canceling circuit. The method can also include applying a signal to an acoustic wave filter using the canceling circuit so as to attenuate a transmission characteristic of the acoustic wave filter within a frequency band outside the pass band of the acoustic wave filter. The method can also include filtering a radio frequency signal with the acoustic wave filter with the attenuated transmission characteristic.

FIG. 5Aillustrates a portion110of an acoustic wave device with IDTs53B and53C of different canceling circuits without an acoustic obstacle disposed therebetween.FIG. 5Billustrates a portion of an acoustic wave device112with an acoustic obstacle63disposed between IDTs53B and53C of canceling circuits. The acoustic obstacle52ofFIG. 5Bincludes patterned metal. The patterned metal is the same material as the IDT electrodes53B and53C inFIG. 5B.FIG. 5Cis a graph of transmission characteristics of the acoustic wave devices ofFIGS. 5A and 5B.FIG. 5Cillustrates that the acoustic obstacle52can improve performance of the canceling circuits. For instance, this graph indicates that the acoustic obstacle52can cut out approximately 13.4 dB of signal.

FIG. 6Aillustrates a portion120of an acoustic wave device test circuit to determine the acoustic communication between IDTs53B and53C without an acoustic obstacle disposed therebetween.FIG. 6Billustrates a portion122of an acoustic wave device test circuit with an acoustic obstacle62disposed between IDTs53B and53C. The acoustic obstacle62ofFIG. 6Bincludes a pillar of acoustic absorbing material. The acoustic absorbing material is the same material as a cavity wall of the acoustic wave device inFIG. 6B.FIG. 6Cis a graph of transmission characteristics of the acoustic wave devices ofFIGS. 6A and 6B.FIG. 6Cillustrates that the acoustic obstacle62can improve performance of the signal attenuation between IDTs53B and53C. This result shows that acoustic obstacles can prevent IDTs from communicating with each other by acoustic coupling. For instance, this graph indicates that acoustic obstacles can suppress a relatively strong spike in the frequency response of the acoustic wave device.

The multiplexers and/or filters discussed herein can be implemented in a variety of packaged modules. Some example packaged modules will now be discussed in which any suitable principles and advantages of the multi-channel feedback circuits that include an acoustic obstacle discussed herein can be implemented.FIGS. 7A, 7B, and 7Care schematic block diagrams of illustrative packaged modules according to certain embodiments.

FIG. 7Ais a schematic block diagram of a module130that includes a duplexer132, a multi-channel feedback circuit134, and an antenna switch136in accordance with one or more embodiments. The module130can include a package that encloses the illustrated elements. The duplexer132, the multi-channel feedback circuit134, and the antenna switch136can be disposed on a common packaging substrate. The packaging substrate can be a laminate substrate, for example. The duplexer132can include any suitable number of acoustic wave resonators. For instance, the duplexer132can include one or more SAW resonators and/or one or more BAW resonators. As illustrated, the multi-channel feedback circuit134is coupled between a receive port Rx and a transmit port Tx of the duplexer132. The multi-channel feedback circuit134can be implemented in accordance with any suitable principles and advantages discussed herein. For example, the multi-channel feedback circuit134can include any suitable acoustic obstacle discussed herein to reduce and/or eliminate acoustic coupling between canceling circuits. The antenna switch136can be a multi-throw radio frequency switch. The antenna switch136can selectively electrically couple a common node of the duplexer232to an antenna port of the module130.

FIG. 7Bis a schematic block diagram of a module140that includes a power amplifier142, a switch144, a duplexer132, and a multi-channel feedback circuit134in accordance with one or more embodiments. The power amplifier142can amplify a radio frequency signal. The switch144can selectively electrically couple an output of the power amplifier144to a transmit port of the duplexer132. The multi-channel feedback circuit134can be implemented in accordance with any suitable principles and advantages discussed herein.

FIG. 7Cis a schematic block diagram of a module150that includes power amplifier142, a switch144, a duplexer132, a multi-channel feedback circuit134, and an antenna switch136in accordance with one or more embodiments. The module150is similar to the module140ofFIG. 7B, except the module150additionally includes the antenna switch136.

FIG. 8is a schematic block diagram of a wireless communication device150that includes duplexers153in accordance with one or more embodiments. The wireless communication device150can be any suitable wireless communication device. For instance, a wireless communication device150can be a mobile phone, such as a smart phone. As illustrated, the wireless communication device150includes an antenna151, an RF front end152, an RF transceiver154, a processor155, and a memory156. The antenna151can transmit RF signals provided by the RF front end152. The antenna151can provide received RF signals to the RF front end152for processing.

The RF front end152can include one or more power amplifiers, one or more low noise amplifiers, RF switches, receive filters, transmit filters, duplex filters, filters of a multiplexer, filters of a diplexers or other frequency multiplexing circuit, or any suitable combination thereof. The RF front end152can transmit and receive RF signals associated with any suitable communication standards. Any of the acoustic wave devices and/or multi-channel feedback circuits discussed herein can be implemented in the RF front end152.

The RF transceiver154can provide RF signals to the RF front end152for amplification and/or other processing. The RF transceiver154can also process an RF signal provided by a low noise amplifier of the RF front end152. The RF transceiver154is in communication with the processor155. The processor155can be a baseband processor. The processor155can provide any suitable base band processing functions for the wireless communication device150. The memory156can be accessed by the processor155. The memory156can store any suitable data for the wireless communication device150.

Any of the embodiments described above can be implemented in association with 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. For instance, while certain embodiments are discussed with reference to duplexers, any suitable principles and advantages can be implemented in association with diplexers and/or other frequency multiplexing circuits. Any of the principles and advantages discussed herein can be implemented in association with RF circuits configured to process signals in a range from about 30 kHz to 300 GHz, such as in a range from about 450 MHz to 6 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 semiconductor die 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 copier, a facsimile machine, a scanner, a multi-functional peripheral device, a wrist watch, a clock, etc. Further, the electronic devices can include unfinished products.