HK40006886B - Acoustic wave filter including two types of acoustic wave resonators - Google Patents

Description

Acoustic filters including two types of acoustic resonators

Cross-references to related applications

This application claims priority to U.S. Provisional Patent Application No. 62/414,253, filed October 28, 2016, entitled “HYBRID SAW/BAW MULTIPLEXER”; U.S. Provisional Patent Application No. 62/426,104, filed November 23, 2016, entitled “HYBRID SURFACEACOUSTIC WAVE AND BULK ACOUSTIC WAVE MULTIPLEXER”; and U.S. Provisional Patent Application No. 62/426,083, filed November 23, 2016, entitled “ACOUSTIC WAVE FILTER INCLUDING SURFACEACOUSTIC WAVE RESONATORS AND BULK ACOUSTIC WAVE RESONATOR”. The disclosure of each of these priority applications is hereby incorporated herein by reference in its entirety.

Technical Field

Embodiments of this application relate to acoustic filters.

Background Technology

Acoustic filters can include multiple resonators arranged to filter radio frequency signals. Example acoustic filters include surface acoustic wave (SAW) filters and bulk acoustic wave (BAW) filters. Thin-film bulk acoustic resonators (FBARs) are an example of BAW filters.

Acoustic filters can be implemented in radio frequency (RF) electronic systems. For example, filters in the RF front-end of a mobile phone may include acoustic filters. Two acoustic filters can be arranged as a duplexer.

Summary of the Invention

Each of the novel inventions described in the claims has several aspects, but no single aspect is solely responsible for its desired properties. Without limiting the scope of the claims, some of the prominent features of this application will now be briefly described.

One aspect of this application is a filter assembly comprising a first acoustic filter coupled to a common node and a second acoustic filter coupled to the common node. The first acoustic filter includes a plurality of surface acoustic wave resonators and a series volume acoustic wave resonator coupled between the plurality of surface acoustic wave resonators and the common node.

The plurality of surface acoustic wave (SAW) resonators may include a series SAW resonator connected in series with the series bulk acoustic wave resonator. The series SAW resonator may be a one-port resonator. The series SAW resonator may be a two-mode SAW resonator.

The first acoustic filter may include surface acoustic wave (SAW) resonators in more than twice the number of bulk acoustic wave (SAW) resonators. The plurality of SAW resonators may constitute at least 70% of the resonators in the first acoustic filter. Alternatively, the plurality of SAW resonators may constitute at least 80% of the resonators in the first acoustic filter.

The series solid acoustic wave resonator can be coupled between all surface acoustic wave resonators of the first acoustic wave filter and the common node. The plurality of surface acoustic wave resonators may include at least five resonators.

The first acoustic filter may further include a shunt bulk acoustic resonator coupled to the common node. The shunt bulk acoustic resonator may be coupled to the plurality of surface acoustic resonators via the series bulk acoustic resonators.

The second acoustic filter may include a plurality of second surface acoustic wave resonators and a second series solid acoustic wave resonator coupled between the plurality of second surface acoustic wave resonators and the common node. The second acoustic filter may include one or more suitable features of the first acoustic filter.

The filter assembly may further include at least two additional acoustic filters coupled to the common node. The filter assembly may further include at least four additional acoustic filters coupled to the common node. The filter assembly may further include at least six additional acoustic filters coupled to the common node.

The filter assembly can be arranged as a triplet. The filter assembly can be arranged as a quadruplet. The filter assembly can be arranged as a quintuplet. The filter assembly can be arranged as a hexaplet. The filter assembly can be arranged as a heptadecimalt. The filter assembly can be arranged as an octadecimalt.

The common node can be an antenna node.

Another aspect of this application is a multiplexer comprising four acoustic filters coupled to a common node. The four acoustic filters include a first acoustic filter comprising a plurality of surface acoustic wave resonators and a series bulk acoustic wave resonator coupled between the plurality of surface acoustic wave resonators and the common node.

The multiplexer can be arranged as a quadruple multiplexer. The multiplexer can be arranged as a quintuple multiplexer. The multiplexer can be arranged as a hexaple multiplexer. The multiplexer can be arranged as a heptapex multiplexer. The multiplexer can be arranged as an octaple multiplexer.

The plurality of surface acoustic wave (SAW) resonators may include a series SAW resonator connected in series with the series bulk acoustic wave resonator. The series SAW resonator may be a single-port resonator. The series SAW resonator may be a two-mode SAW resonator.

The plurality of surface acoustic wave (SAW) resonators can realize at least 70% of the resonators of the first acoustic wave filter. The plurality of SAW resonators can realize at least 80% of the resonators of the first acoustic wave filter. At least 70% of the resonators of the multiplexer can be SAW resonators. At least 80% of the resonators of the multiplexer can be SAW resonators.

The series solid acoustic wave resonator can be coupled between all surface acoustic wave resonators of the first acoustic wave filter and the common node. The surface acoustic wave resonator can include at least five resonators.

The first acoustic filter may further include a shunt acoustic resonator coupled to the common node. The shunt acoustic resonator may be coupled to the plurality of surface acoustic resonators via the series volume acoustic resonator.

The four acoustic filters may include a second acoustic filter, which includes a plurality of second surface acoustic wave resonators and a second series acoustic resonator coupled between the plurality of second surface acoustic wave resonators and the common node. The second acoustic filter may include one or more suitable features of the first acoustic filter. The four acoustic filters may also include a third acoustic filter, which includes a plurality of third surface acoustic wave resonators and a third series acoustic resonator coupled between the plurality of third surface acoustic wave resonators and the common node. The third acoustic filter may include one or more suitable features of the first acoustic filter. The four acoustic filters may also include a fourth acoustic filter, which includes a plurality of fourth surface acoustic wave resonators and a fourth series acoustic resonator coupled between the plurality of fourth surface acoustic wave resonators and the common node. The fourth acoustic filter may include one or more suitable features of the first acoustic filter.

Another aspect of this application is a packaging module comprising one or more first dies and a second die. The one or more first dies include a first set of surface acoustic wave (SAW) resonators and a second set of SAW resonators. The first set of SAW resonators is included in a first acoustic wave filter coupled to a common node. The second die includes a series volume acoustic wave (SAW) resonator. The second SAW resonator and the series volume acoustic wave (SAW) resonator are included in a second acoustic wave filter coupled to the common node. The series volume acoustic wave (SAW) resonator is coupled between the second set of SAW resonators and the common node.

The packaging module may further include a multi-throw switch coupled to the first filter and the second filter. The multi-throw switch may have a single throw coupled to the common node. Alternatively, the multi-throw switch may have a first throw coupled to the first acoustic filter and a second throw coupled to the second acoustic filter. In some instances, the packaging module may further include a power amplifier configured to provide an RF signal to at least one of the first acoustic filter or the second acoustic filter via the multi-throw switch.

The packaging module may also include a power amplifier.

The encapsulation module may also include one or more suitable features of the acoustic filter and/or multiplexer described herein.

Another aspect of this application is a wireless communication device, the wireless communication device including an antenna configured to receive radio frequency signals and a multiplexer communicating with the antenna. The multiplexer includes four acoustic filters coupled to a common node. The four acoustic filters include a first acoustic filter, the first acoustic filter including a plurality of surface acoustic wave resonators and a series volume acoustic resonator coupled between the plurality of surface acoustic wave resonators and the common node.

The wireless communication device can be configured as a mobile phone.

The wireless communication device may further include a frequency multiplexing circuit coupled between the public node and the antenna. The frequency multiplexing circuit may be a diplexer or a tripeller.

The wireless communication device may further include an antenna switch coupled between the public node and the antenna.

The radio frequency signal may be a carrier aggregation signal.

The antenna may be a main antenna. The antenna may be a diversity antenna. Each of the four acoustic filters may be configured as a receiving filter that communicates with the diversity antenna.

The wireless communication device may include one or more suitable features of any acoustic filter described herein, any multiplexer described herein, any encapsulation module described herein, or any combination thereof.

Another aspect of this application is a filter assembly comprising a first acoustic filter having a passband and coupled to a common node. The filter assembly further comprises a second acoustic filter coupled to the common node. The second acoustic filter comprises a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the common node. The series acoustic resonator of the second type has a higher quality factor in the passband of the first acoustic filter than the plurality of acoustic resonators of the first type.

The first type of multiple acoustic resonators can be multiple surface acoustic wave (SAW) resonators, and the second type of series acoustic resonator can be a bulk acoustic wave (SAW) resonator. The first type of multiple acoustic resonators can be multiple uncompensated SAW resonators, and the second type of series acoustic resonator can be a temperature-compensated SAW resonator.

The plurality of acoustic resonators of the first type in the second acoustic filter may comprise at least 70% of the resonators in the second acoustic filter. The filter assembly may include a first wafer and a second wafer, the first wafer comprising the plurality of acoustic resonators of the first type, and the second wafer comprising a series acoustic resonator of the second type. At least two of the plurality of acoustic resonators of the first type may be connected in series with the series acoustic resonator of the second type.

The filter assembly may further include a third acoustic filter coupled to the common node and a fourth acoustic filter coupled to the common node. The second type of series acoustic resonator may have a higher quality factor in the passband of the third acoustic filter than the first type of multiple acoustic resonators. The second type of series acoustic resonator may have a higher quality factor in the passband of the fourth acoustic filter than the first type of multiple acoustic resonators.

Another aspect of this application is a multiplexer with multiple acoustic filters. The multiplexer includes a first acoustic filter coupled to a common node and three other acoustic filters coupled to the common node. The first acoustic filter includes a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the common node. Each of the three other acoustic filters has a corresponding passband. The series acoustic resonator of the second type has a higher quality factor than the plurality of acoustic resonators of the first type in each of the corresponding passbands of the three other acoustic filters.

The first type of multiple acoustic resonators can be multiple surface acoustic wave (SAW) resonators, and the second type of series acoustic resonator can be a bulk acoustic wave (SAW) resonator. The first type of multiple acoustic resonators can be multiple uncompensated SAW resonators, and the second type of series acoustic resonator can be a temperature-compensated SAW resonator.

At least one of the three other acoustic filters may include a plurality of second acoustic resonators of the first type and a second series acoustic resonator of the second type coupled between the plurality of second acoustic resonators of the first type and the common node.

The multiplexer may be a quadruple. The multiplexer may also include two additional acoustic filters coupled to the common node.

Another aspect of this application is a method for processing carrier aggregation signals. The method includes filtering the carrier aggregation signal with a first acoustic filter coupled to an antenna port and having a first passband. The carrier aggregation signal includes a first radio frequency carrier in the first passband and a second radio frequency carrier in a second passband. The method further includes filtering the carrier aggregation signal with a second acoustic filter coupled to the antenna port and having a second passband. The second acoustic filter includes a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the antenna port. The series acoustic resonator of the second type has lower load loss than the plurality of acoustic resonators of the first type.

The method further includes receiving the carrier aggregation signal via an antenna coupled to the antenna port. The method also includes transmitting the carrier aggregation signal via an antenna coupled to the antenna port. The method further includes coupling the first acoustic filter and the second acoustic filter to a common node via a multi-throw switch. The multi-throw switch can couple the first acoustic filter and the second acoustic filter to the common node such that the first acoustic filter and the second acoustic filter are simultaneously coupled to the common node.

The first type of multiple acoustic resonators can be multiple surface acoustic wave (SAW) resonators, and the second type of series acoustic resonator can be a bulk acoustic wave (SAW) resonator. The first type of multiple acoustic resonators can be multiple uncompensated SAW resonators, and the second type of series acoustic resonator can be a temperature-compensated SAW resonator. The first type of multiple acoustic resonators and the second type of series acoustic resonator can be on different wafers.

For the purpose of outlining the disclosure, some aspects, advantages, and novel features of the new invention have been described herein. It should be understood that not all of these advantages can necessarily be implemented according to any particular embodiment. Therefore, various new inventions may be implemented or performed by taking into account or optimizing one or more advantages taught herein without necessarily implementing other advantages that may be taught or implied herein.

Attached Figure Description

Embodiments of this application will be described with reference to the accompanying drawings and by way of non-limiting examples.

Figure 1 is a schematic diagram of a four-tool.

Figure 2A is a schematic diagram of a four-channel acoustic resonator according to an embodiment.

Figure 2B is a schematic diagram of the acoustic resonator of the four-channel resonator according to an embodiment.

Figure 2C is a schematic diagram of a four-channel acoustic resonator according to an embodiment.

Figure 3 is a schematic diagram of a six-tool.

Figure 4 is a schematic diagram of the acoustic resonator of the six-channel resonator according to an embodiment.

Figure 5 is a schematic diagram of the acoustic resonator of the multiplexer according to an embodiment.

Figure 6 is a schematic diagram of the acoustic resonator of a multiplexer according to another embodiment.

Figure 7 is a schematic diagram of a radio frequency system including a quadrupole coupled to an antenna via dual transducers.

Figure 8 is a schematic diagram of a radio frequency system including a quadrupole coupled to an antenna.

Figure 9 is a schematic diagram of an RF system including an antenna coupled to the receiving path via a multiplexer.

Figure 10A is a schematic diagram of an RF system that includes multiple multiplexers in the signal path between the power amplifier and the antenna.

Figure 10B is a schematic diagram of another radio frequency system that includes multiple multiplexers in the signal path between the power amplifier and the antenna.

Figure 10C is a schematic diagram of the acoustic resonator of the multiplexer according to an embodiment.

Figure 11A is a block diagram illustrating different wafers, which include acoustic resonators of filters according to embodiments described herein.

Figure 11B is a block diagram illustrating different wafers, which include acoustic resonators of filters according to embodiments described herein.

Figure 11C is a block diagram illustrating different wafers, which include acoustic resonators of filters according to embodiments described herein.

Figure 12 is a schematic block diagram of a module including a power amplifier, a switch, and a filter according to one or more embodiments.

Figure 13 is a schematic block diagram of a module including multiple power amplifiers, multiple switches, and filters according to one or more embodiments.

Figure 14 is a schematic block diagram of a module including a power amplifier, a switch, a filter according to one or more embodiments, and an antenna switch.

Figure 15 is a schematic block diagram of a wireless communication device including a filter according to one or more embodiments.

Detailed Implementation

The following detailed descriptions of some embodiments present various descriptions of specific embodiments. However, the new invention described herein can be implemented in many different ways, for example, as defined and covered by the claims. In this description, reference is made to the accompanying drawings, wherein similar reference numerals may indicate the same or functionally similar elements. It should be understood that the elements illustrated in the drawings are not necessarily drawn to scale. Moreover, it should be understood that some embodiments may include more elements than illustrated in the drawings and/or a subset of the elements illustrated in the drawings. Additionally, some embodiments may incorporate any suitable combination of features from two or more drawings.

To increase cellular data bandwidth, service providers and handset manufacturers often implement carrier aggregation (CA), in which a single handset simultaneously uses multiple frequency bands for data transmission and/or reception. Because handset size and cost allow manufacturers to use as few separate antennas as possible, many CA solutions benefit from multiple frequency bands sharing a single antenna.

While traditional single-band (non-CA) configurations involve a maximum of two bandpass filters connected to the antenna (one transmit filter and one receive filter, a combination that can be referred to as a duplexer), CA systems can include many more filters, all connected to a common antenna node. Depending on the CA specification, these filters can be configured as quadplexers (four filters), pentplexers (five filters), hexplexers (six filters), octplexers (eight filters), and so on. The general term used throughout this document for all these multi-filter configurations is multiplexer.

In situations where multiple filters share a common connection, it is desirable to ensure that each filter presents a high impedance to each other in the corresponding passband of the other filters. This ensures that the mutual load of these filters remains at or near a minimum. In this context, "load" refers to the increased insertion loss through a filter caused by unwanted signal dissipation and/or redirection from one or more other filters in the multiplexer.

As an example, consider a duplexer comprising two filters connected together to share a common antenna, used for two frequency bands (band X and band Y). The duplexer can be viewed as a power divider, where the amount of power through each path can be determined by the frequency-dependent impedance presented by each of the two filters. If the filters are ideal, they present a perfect 50-ohm antenna impedance in their respective passbands, while presenting an open-circuit impedance in the passband of the other filter of the duplexer. In such a case, for example, a signal with its antenna port in band X will see 50 ohms through the band X filter and an open circuit through the band Y filter. Thus, in this ideal case, 100% of the signal power will flow through the band X filter, and 0% will flow through band Y. Similarly, for a signal in band Y, in this ideal case, 100% of the power will flow through the band Y filter, and 0% will flow through the band X filter. On the other hand, if the filters are very poor, such that they present 50 ohms at all frequencies, the power distribution will be very different. In the band X example, the signal will now be presented to two filters through a 50-ohm path. Therefore, power will be distributed so that 50% flows through the band X filter and 50% flows through the band Y filter. This will increase the insertion loss of band X by approximately 3 dB. In other words, the duplexer will have a 3 dB load loss compared to a single filter.

As can be seen, the total load loss increases rapidly with the number of combined filters in the multiplexer. For example, an octet including such a non-ideal filter can have an additional 9 dB of load loss. Real-world radio frequency (RF) filters are not as good as the ideal filters described above that have no load loss at all, but they will not behave as badly as a 50-ohm impedance at all frequencies. The magnitude of the out-of-band impedance can be strongly dependent on the filter design, but it can also depend on the filter technology.

Surface acoustic wave (SAW) and bulk acoustic wave (BAW) technologies are both widely used in RF filters, and both can achieve relatively high out-of-band impedance values. However, world-class BAW filters generally outperform SAW filters in terms of out-of-band impedance values over a wider frequency span. For duplexers, the difference in load loss is relatively small, but it becomes more significant as the number of CA filter combinations increases. In the case of quadplexers, BAW filters often show a 0.5 dB to 1.0 dB advantage in load loss compared to their SAW filter counterparts. For hexaplexers and octaplexers, the difference is much greater.

Unfortunately, while BAW filters offer superior performance, they come with a significant drawback compared to SAW filters: cost. BAW filters are generally much more difficult and expensive to manufacture than SAW filters. Therefore, there is a substantial motivation to use SAW technology whenever possible. SAW technology is sufficient to enable duplexers to cover most current cellular frequency bands. However, for CA combinations using quadduplexers, the cost-performance trade-off between the two technologies is less clear. For more complex connections such as hexadecimalers and octaduplexers, SAW performance often degrades significantly, making it often an undesirable option despite cost savings.

Some methods improve load loss by carefully controlling filter topology and/or design parameters. However, load loss can ultimately be limited by factors such as spurious noise modes and out-of-band acoustic energy radiation outside the resonator due to the limited reflection bandwidth of the Bragg reflector used to confine in-band energy. For situations where the cost/performance tradeoff is somewhat ambiguous, such as quad- or quintet-type multiplexers, existing RF switches within the cellular front-end module can be used to create so-called “switch-plexers” or “multiplexers.” In this case, a common CA connection is facilitated using multi-pole multi-throw RF switches that allow filters to be used in conventional single-band configurations or as CA combinations. In CA mode, load loss is slightly worse than that of hardwired multiplexers (and worse than BAW multiplexers), but in non-CA mode, load loss can be eliminated. Since most of the total usage time of some cellular phones is in non-CA mode, the degraded performance (relative to BAW) can be primarily limited to CA mode, which can enhance the advantages of the less expensive SAW solutions in such cellular phones. While switch multiplexer solutions are good, they may be more difficult to implement than permanent multiplexing solutions. Furthermore, for mobile phone manufacturers, they can involve more complex and expensive calibration routines. As CA operations become more common and the number of simultaneous connections increases, SAW technology is expected to struggle to meet certain CA specifications.

Some aspects of this application address the aforementioned problems by combining both SAW and BAW technologies in a single system. Because the out-of-band impedance presented by each filter of the multiplexer can be determined primarily by one or two resonators closest to the antenna connection, BAW technology can be used to create those specific resonators. According to some embodiments, these BAW resonators may comprise approximately 10-30% of the total number of resonators in the filter, and most or all of the remaining 70-90% of the resonators in the filter can be implemented using the less expensive SAW technology. The multiplexer may comprise approximately 10-30% BAW resonators, and most or all of the remaining 70-90% of the resonators in the multiplexer may be SAW resonators. Therefore, some embodiments may include a sextupler or octupler, which has the same load loss as a full BAW solution but at a much lower cost due to the majority being SAW. Thus, according to some embodiments, the system includes one or more BAW resonators of a first number near the antenna connection and a second number of SAW resonators further away from the antenna connection, wherein the second number is greater than the first number.

Some implementations combine the load loss advantages of a full BAW CA multiplexer with the many cost advantages of a full SAW solution.

One aspect of this application is a filter assembly comprising multiple acoustic filters coupled to a common node. A first acoustic filter of the multiple acoustic filters includes multiple surface acoustic wave (SAW) resonators and a bulk acoustic wave (BAW) resonator arranged in series between all SAW resonators of the first acoustic filter and the common node. One or more of the other acoustic filters of the multiple acoustic filters may include multiple SAW resonators coupled to the common node via series BAW resonators. For example, the BAW resonator may be an FBAR. The first acoustic filter may also include a shunt acoustic wave resonator. The multiple acoustic filters may be arranged as multiplexers, such as duplexers, tripplexers, quadplexers, quincunxers, hexadecimalers, heptaplexers, octaplexers, etc.

Another aspect of this application is a multiplexer comprising at least four filters connected to a common node. At least one of the four filters includes at least a first-type resonator and a second-type resonator, wherein the second-type resonator has lower load losses than the first-type resonator. In one of the four filters, all first-type resonators are coupled to the common node via a second-type series resonator. The second-type resonator may be a BAW resonator, such as an FBAR, and the first-type resonator may be a SAW resonator.

The antenna is configured to receive radio frequency (RF) signals. A multiplexer communicates with the antenna. The multiplexer includes four acoustic filters coupled to a common node. The first acoustic filter of the four acoustic filters includes multiple surface acoustic wave (SAW) resonators and a bulk acoustic wave (BAW) resonator connected in series between the SAW resonators and the common node. Frequency multiplexing circuitry such as a dual-signaler or tripeller and/or an antenna switch may be coupled between the multiplexer and the switch. The RF signal may be a carrier aggregation signal. In some applications, the antenna may be a diversity antenna and the four filters may be receive filters. The multiplexer may include one or more additional acoustic filters coupled to the common node.

Another aspect of this application is a package module comprising one or more first wafers and second wafers. The one or more first wafers include multiple SAW resonators. The second wafer includes a BAW resonator. An acoustic filter coupled to a common node is implemented via acoustic resonators on the one or more first wafers and second wafers. A first acoustic filter of the multiple acoustic filters includes multiple SAW resonators and a BAW resonator connected in series between the multiple SAW resonators and the common node. The multiple acoustic filters can be arranged as multiplexers, such as quad-multiplexers, quintuples, sextuples, octa-multiplexers, etc. The package module may also include one or more of a power amplifier, a band selection switch, and an antenna switch.

Another aspect of this application is a wireless communication device including an antenna and a multiplexer. The antenna is configured to receive radio frequency (RF) signals. The multiplexer communicates with the antenna. The multiplexer includes four acoustic filters coupled to a common node. A first acoustic filter of the four acoustic filters includes multiple surface acoustic wave (SAW) resonators and a bulk acoustic wave (BAW) resonator connected in series between the multiple SAW resonators and the common node. Frequency multiplexing circuitry such as dual-signalers or trippers and/or antenna switches may be coupled between the multiplexer and the antenna. The RF signal may be a carrier aggregation signal. In some applications, the antenna may be a diversity antenna and the four filters may be receive filters. The multiplexer may include one or more additional acoustic filters coupled to the common node.

Figure 1 is a schematic diagram of a quadrature 10. The quadrature 10 includes four filters connected to a common node COM. The common node COM may be referred to as a common port. As shown, the quadrature 10 includes a first transmit filter 12, a first receive filter 14, a second transmit filter 16, and a second receive filter 18. Each filter of the quadrature 10 may be an illustrated bandpass filter. One or more filters of the quadrature 10 may be acoustic filters. All filters of the quadrature 10 may be acoustic filters. Any filter of the quadrature 10 may include two types of acoustic resonators according to the principles and advantages described herein. For example, any filter of the quadrature 10 may include multiple SAW resonators and one or more BAW resonators according to the principles and advantages described herein.

Figure 2A is a schematic diagram of the acoustic resonator of a quadrupler 20 according to an embodiment. The quadrupler 20 is an example of the quadrupler 10 of Figure 1. Multiplexers can be implemented according to the appropriate principles and advantages described with reference to Figure 2A. In Figure 2A, each filter of the quadrupler 20 is implemented via an acoustic resonator. Each illustrated acoustic resonator is a 1-port resonator. Such a resonator may include interdigitated transducer electrodes, wherein the input and output of the resonator are opposite bus bars of the interdigitated transducer electrodes.

The first acoustic filter of the quadruple acoustic transducer 20 includes SAW resonators 21, 22, 23, and 24 and BAW resonator 25. The second acoustic filter of the quadruple acoustic transducer 20 includes SAW resonators 31, 32, 33, and 34 and BAW resonator 36. The third acoustic filter of the quadruple acoustic transducer 20 includes SAW resonators 41, 42, 43, 44, and 45 and BAW resonators 46 and 47. The fourth acoustic filter of the quadruple acoustic transducer 20 includes SAW resonators 51, 52, 53, 54, and 55 and BAW resonator 56.

As shown in Figure 2A, the series SAW resonators in the acoustic filter can be coupled to the common node of the quadrupler via series BAW resonators. Also as shown in Figure 2A, the series SAW resonators and shunt SAW resonators in the acoustic filter can be coupled to the common node of the quadrupler via series BAW resonators. Figure 2A also shows that at least four or at least five SAW resonators can be coupled to the common node of the quadrupler via series BAW resonators.

In the acoustic filter illustrated in Figure 2A, all SAW resonators of each acoustic filter are coupled to a common node via cascaded BAW resonators of the respective acoustic filter. This reduces the load on the common node compared to an acoustic filter that only includes SAW resonators. Also as shown in Figure 2A, at least 70% of the resonators in the multiplexer and/or acoustic filter can be SAW resonators, while the remaining resonators of the multiplexer and/or acoustic filter can be implemented using BAW technology. By primarily using SAW resonators to implement the acoustic filter, such an acoustic filter can be less expensive than an acoustic filter implemented primarily or entirely with BAW resonators.

While Figure 2A and other embodiments such as Figures 4 through 6 illustrate example multiplexers including SAW and BAW resonators, any suitable principles and advantages described herein can be implemented using two different suitable types of resonators. For example, the filter of the multiplexer may include a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and a common node of the multiplexer.

The second type of resonator can have lower load loss than the first type of resonator. Such load loss can refer to the loss associated with the increased insertion loss through a filter caused by unwanted signal dissipation and/or redirection from one or more other filters in the multiplexer.

The second type of resonator can have higher out-of-band rejection than multiple acoustic resonators of the first type. The second type of resonator can also have a higher out-of-band quality factor than the first type of resonator. For example, a second type of resonator can have a higher quality factor in the passband of at least one other filter in a multiplexer than a first type of acoustic resonator. With a higher out-of-band quality factor, the second type of resonator can provide more out-of-band rejection and less energy dissipation than the first type of resonator. In some applications, the second type of resonator can have a higher quality factor in the corresponding passband of all other filters in a multiplexer than a first type of acoustic resonator. The quality factor can represent the ratio of stored power to dissipated power. The quality factor can be frequency-dependent.

The second type of acoustic resonator can be more expensive than the first type but can achieve better out-of-band performance. By implementing an acoustic filter using both types of resonators, a balance can be struck between out-of-band performance and cost in a solution that offers relatively low cost and relatively high performance.

In the multiplexer 20 of Figure 2A, the first type of resonator is a SAW resonator, and the second type of resonator is a BAW resonator. Other example multiplexers with two different types of resonators will be described with reference to Figures 2B and 2C.

Figure 2B is a schematic diagram of the acoustic resonator of a quadrupler 20' according to an embodiment. The quadrupler 20' includes two types of SAW resonators, SAW type A and SAW type B. The quadrupler 20' is similar to the quadrupler 20 of Figure 2A, except that a second type of SAW resonator is implemented in the quadrupler 20' to replace the BAW resonator of the quadrupler 20. The second type of SAW resonator, SAW type B, can be superior to the first type of SAW resonator, SAW type A, in a similar way to the BAW resonator. For example, the second type of SAW resonator, SAW type B, can have lower load losses and/or better out-of-band rejection and/or higher out-of-band quality factor than the first type of SAW resonator, SAW type A. At the same time, implementing the second type of SAW resonator, SAW type B, can be more expensive than implementing the first type of SAW resonator, SAW type A. Therefore, the filter topology shown in Figure 2B can balance cost and performance, thus providing a solution with relatively low cost and relatively high performance.

In some instances, the first type of SAW resonator, SAW type A, can be a standard SAW resonator, and the second type of SAW resonator, SAW type B, can be a temperature-compensated SAW (TCSAW) resonator. A standard SAW resonator can be non-temperature compensated. A TCSAW resonator can include a temperature-compensated layer with a positive temperature coefficient of frequency. For example, a TCSAW resonator can be a standard SAW resonator with a silicon dioxide layer on the IDT electrodes.

According to some embodiments, the second type of SAW resonator, SAW type B, can be a SAW resonator having characteristics equivalent to or better than those of a typical BAW resonator, which has superior temperature characteristics compared to a standard BAW resonator. Such a second type of SAW resonator can have a relatively high quality factor, a relatively low temperature coefficient of frequency, and relatively high heat dissipation. This second type of SAW resonator can have a multilayer substrate that can improve the quality factor and reduce the temperature coefficient of frequency relative to a standard SAW resonator. The second SAW resonator can include an IDT electrode on a multilayer substrate comprising a piezoelectric layer (e.g., lithium niobate (LN) or lithium tantalate (LT)) on a high-speed layer (e.g., sapphire, bauxite, SiN, or _AlN ) on a supporting substrate (e.g., silicon), a functional layer (e.g., _SiO2 , SiON, or _Ta2O5 ) on top of that layer. For example, the second type of SAW resonator can include an IDT electrode on an LT/ _SiO2 /AlN/Si substrate. The second type of SAW resonator can be an Incredible High-Performance (IHP) SAW resonator from Murata Manufacturing Co., Ltd. With this second type of SAW resonator in the quadrupler 20', the first type of SAW resonator in the quadrupler 20 can be a non-temperature-compensated SAW resonator or a temperature-compensated SAW resonator.

The first acoustic filter of the quad-channel 20' includes SAW resonators 21', 22', 23', and 24' of type I and SAW resonator 25' of type II. The second acoustic filter of the quad-channel 20' includes SAW resonators 31', 32', 33', and 34' of type I and SAW resonator 36' of type II. The third acoustic filter of the quad-channel 20' includes SAW resonators 41', 42', 43', 44', and 45' of type I and SAW resonators 46' and 47' of type II. The fourth acoustic filter of the quad-channel 20' includes SAW resonators 51', 52', 53', 54', and 55' of type I and SAW resonator 56' of type II.

Figure 2C is a schematic diagram of a quadruple acoustic resonator 20” according to an embodiment. The quadruple 20” includes two types of resonators, resonator type A and resonator type B. The quadruple 20” is similar to the quadruple 20 of Figure 2A and the quadruple 20’ of Figure 2B, except that the two types of resonators in the quadruple 20” can be any suitable type of resonator. The second type of resonator can be superior to the first type of resonator in a similar way to how BAW resonators are superior to SAW resonators. For example, the second type of resonator can have any of the advantages described above related to lower load loss, better out-of-band rejection, higher out-of-band quality factor, etc., than the first type of resonator, or any suitable combination of these advantages. At the same time, implementing the second type of resonator can be more expensive than implementing the first type of resonator. Therefore, the filter topology shown in Figure 2C can balance cost and performance, thus providing a solution with relatively low cost and relatively high performance.

The first filter of the quad-channel 20” includes resonators of type 1, 21”, 22”, 23”, and 24”, and a resonator of type 2, 25”. The second filter of the quad-channel 20” includes resonators of type 1, 31”, 32”, 33”, and 34”, and a resonator of type 2, 36”. The third filter of the quad-channel 20” includes resonators of type 1, 41”, 42”, 43”, 44”, and 45”, and resonators of type 2, 46” and 47”. The fourth filter of the quad-channel 20” includes resonators of type 1, 51”, 52”, 53”, 54”, and 55”, and a resonator of type 2, 56”. All the resonators exemplified in the quad-channel 20” can be acoustic resonators.

Figure 3 is a schematic diagram of a sextiller 60. The sextiller 60 includes six filters connected to a common node COM. As shown, the sextiller 60 includes a first transmit filter 12, a first receive filter 14, a second transmit filter 16, a second receive filter 18, a third transmit filter 62, and a third receive filter 64. Each filter of the sextiller 60 can be an illustrated bandpass filter. One or more filters of the sextiller 60 can be acoustic filters. All filters of the sextiller 60 can be acoustic filters. Any filter of the sextiller 60 can include two types of acoustic resonators according to the principles and advantages described herein. For example, any filter of the sextiller 60 can include multiple SAW resonators and one or more BAW resonators according to the principles and advantages described herein.

Figure 4 is a schematic diagram of the acoustic resonator of a sextupler 70 according to an embodiment. The sextupler 70 is an example of the sextupler 60 of Figure 3. As shown in Figure 4, each filter of the sextupler 70 is implemented by an acoustic filter. The multiplexer can be implemented according to the appropriate principles and advantages described with reference to Figure 4. Specific filters of such a multiplexer can be implemented for the design specifications of a given application. The acoustic filters in Figure 4 show some examples of such filters.

The first acoustic wave filter of the six-channel instrument 70 includes a BAW resonator 71 and SAW resonators 71, 72, 73, 74, 75, 76, 77, 78, and 79. The first acoustic wave filter can be a transmission filter, such as the first transmission filter in Figure 3. The SAW resonators account for 8/9 of the acoustic wave resonators in the first acoustic wave filter.

The second acoustic filter of the hexadecimal 70 includes a BAW resonator and SAW resonators 81 and 83. The second acoustic filter can be a receiving filter, such as the first receiving filter 14 in Figure 3. The illustrated SAW resonator 83 is a dual-mode SAW (DMS) resonator, which can also be referred to as a coupled resonator filter (CRF). DMS resonators can be implemented in low-power filters such as receiving filters. DMS resonators typically do not handle relatively high power. Therefore, at least one series acoustic resonator should protect the DMS resonator from the relatively high power presented at the common node COM, which can be an antenna node.

The third acoustic filter of the hexadecimal 70 includes a BAW resonator 91 and SAW resonators 92, 93, 94, 95, 96, 97, and 98. The third acoustic filter can be a transmission filter, such as the second transmission filter 16 in Figure 3.

The fourth acoustic filter of the hexadecimal 70 includes a BAW resonator 101 and SAW resonators 102, 103, and 105. The fourth acoustic filter can be a receiving filter, such as the second receiving filter 18 in Figure 3.

The fifth acoustic filter of the hexadecimal 70 includes a BAW resonator 111 and SAW resonators 122, 123, 124, and 125. The fifth acoustic filter can be a transmit filter, such as the third transmit filter 62 in Figure 3. The fifth acoustic filter exemplifies that shunt BAW resonators and series BAW resonators can be coupled to the common node COM of the multiplexer. The shunt BAW resonator 112 is coupled to the opposite side of the series BAW resonator 111 compared to the SAW resonator of the fifth acoustic filter.

The sixth acoustic filter of the hexadecimal 70 includes SAW resonators 122, 123, 124, and 125. The sixth acoustic filter can be a receiving filter, such as the third receiving filter 64 in Figure 3. One or more filters in the multiplexer, exemplified by the sixth acoustic filter, can be implemented using only SAW resonators.

Figure 5 is a schematic diagram of the acoustic resonators of a multiplexer according to an embodiment. The multiplexer may include any suitable number of acoustic filters. For example, the multiplexer may be a quadrupler with four filters, a quintupler with five filters, a hexadecimalror with six filters, an octadecimalror with eight filters, etc. In some instances, multiplexer 130 may include 2 to 16 acoustic filters connected to a common node COM. The acoustic filters of multiplexer 130 may include any suitable combination of receive filters and/or transmit filters. Each input/output (I/O) port of the acoustic filter may be an input of a transmit filter or an output of a receive filter. Each acoustic filter may include multiple SAW resonators coupled to the common node via series BAW resonators. For example, the first acoustic filter of multiplexer 130 includes SAW resonators 132, 133, 134, and 135 and BAW resonator 136, wherein all SAW resonators 132, 133, 134, and 135 are coupled to the common node COM via a series BAW resonator 136. The Nth acoustic filter of multiplexer 130 includes SAW resonators 142, 143, 144, and 145 and BAW resonator 146, wherein all SAW resonators 142, 143, 144, and 145 are coupled to the common node COM via a series BAW resonator 146.

Figure 6 is a schematic diagram of the acoustic resonators of a multiplexer 150 according to an embodiment. The multiplexer 150 is similar to the multiplexer 130 of Figure 5, except that the multiplexer 150 includes an acoustic filter implemented using only SAW resonators. Figure 6 illustrates that one or more acoustic filters of the multiplexer may include multiple SAW resonators and may not include any BAW resonators. For example, the first acoustic filter of the multiplexer 150 includes SAW resonators 152, 153, 154, 155, and 156, and does not include any BAW resonators. The multiplexer 150 also includes one or more acoustic filters having multiple SAW resonators coupled to a common node via series BAW resonators. For example, the Nth acoustic filter of the multiplexer 150 includes SAW resonators 162, 163, 164 and 165 and BAW resonator 166, wherein all SAW resonators 162, 163, 164 and 165 are coupled to the common node COM via the series BAW resonator 166.

Any appropriate number of BAW resonators can be coupled between the SAW resonators of the filter and the common node. For example, a series BAW resonator, along with one or more other series BAW resonators and/or one or more shunt BAW resonators, can be coupled between the SAW resonators of the filter and the common node.

The multiplexers described herein can be implemented in a wide variety of radio frequency (RF) systems. RF signals can be processed with frequencies ranging from approximately 30 kHz to 300 GHz (e.g., from approximately 450 MHz to 6 GHz). Some RF systems, including multiplexers based on the principles and advantages described herein, are configured to process carrier-aggregated signals. In RF systems with carrier aggregation, multiple filters can be arranged as multiplexers and can be connected to a common antenna node. Some example RF systems that can implement any suitable principles and advantages of the multiplexers and/or filters described herein will now be described.

Figures 7, 8, 9, 10A, and 10B are schematic block diagrams of exemplary radio frequency (RF) systems according to some embodiments. Multiplexers in these RF systems can have reduced load losses due to the presence of BAW resonators coupled between SAW resonators and a common node in one or more acoustic filters. Implementing one or more of these acoustic filters with a majority of SAW resonators can also reduce costs compared to similar acoustic filters implemented primarily with BAW elements. The principles and advantages of filters comprising multiple SAW resonators and one or more BAW resonators can be applied to filters comprising any two different types of acoustic resonators. Each filter in the multiplexer of the RF systems described herein can be a bandpass filter.

Figure 7 is a schematic diagram of a radio frequency system 170 including a quadrupler coupled to an antenna 177 via a dual transducer 176. In Figure 7, the first quadrupler includes acoustic filters 12, 14, 16, and 18. In Figure 7, the second quadrupler includes acoustic filters 172, 173, 174, and 175. The dual transducer 176 can be used for frequency multiplexing of radio frequency signals propagating between the illustrated quadrupler and the antenna 177.

Figure 8 is a schematic diagram of an RF system 180 including a quadplexer coupled to antenna 177. Figure 8 illustrates that in some applications, a multiplexer can be connected to the antenna without intervening frequency multiplexing circuitry (e.g., a dual-signaler or triplexer). For example, when the carrier aggregation signal comprises two carriers relatively close in frequency, a dual-signaler or triplexer may be relatively difficult to implement and/or expensive to implement and/or have relatively high losses. In such cases, multiple filters can be connected together at a common node as a multiplexer. As an example, such a multiplexer could be a quadplexer with transmit and receive filters for bands 25 and 26. As shown in Figure 8, in some applications, a multiplexer can be connected to the antenna without intervening switches or frequency multiplexing circuitry. For example, a mobile circuit configured for wireless communication using carrier aggregation signals from only two carrier aggregation bands could include a multiplexer connected to the antenna without intervening switches or frequency multiplexing circuitry.

Figure 9 is a schematic diagram of a radio frequency system 190 including an antenna 192 coupled to a receive path via a multiplexer. In some instances, the radio can be implemented for diversity reception operation. A diversity antenna, such as the illustrated antenna 192, can provide the received radio frequency signal to several receive paths. A multiplexer can be coupled between multiple receive paths and diversity antennas. As shown in Figure 9, a multiplexer (e.g., a quadplexer) including receive filters 193 and 194 can be coupled between receive path 195 and antenna 192 and between receive path 194 and antenna 192, respectively. For a specific implementation, any suitable number of receive paths and corresponding receive filters can be implemented. For example, in some instances, four or more receive filters can be included in the multiplexer and the corresponding receive paths. In some embodiments (not illustrated), a switch can be coupled between the multiplexer and the diversity antenna and/or a switch can be coupled between the receive path and the receive filter of the multiplexer.

Figure 10A is a schematic diagram of an RF system 200 including multiple multiplexers in multiple signal paths between the power amplifier and antenna 177. The illustrated RF system 200 includes low-frequency band paths, mid-frequency band paths, and high-frequency band paths. In some applications, the low-frequency band path can handle RF signals with frequencies below 1 GHz, the mid-frequency band path can handle RF signals with frequencies between 1 GHz and 2.2 GHz, and the high-frequency band path can handle RF signals with frequencies above 2.2 GHz.

Frequency multiplexing circuitry, such as dual-signaler 176, can be included between the signal path and antenna 176. Such frequency multiplexing circuitry can be used as a frequency splitter for the receive path and a frequency combiner for the transmit path. Dual-signaler 176 can frequency multiplex radio frequency signals that are relatively far apart in frequency. Dual-signaler 176 can be implemented using passive circuitry elements with relatively low loss. Dual-signaler 176 can combine (for transmit) and separate (for receive) carrier aggregation signals.

As shown, the low-frequency path includes a power amplifier 201 configured to amplify low-frequency radio frequency signals, a band selection switch 202, and a multiplexer 203. The band selection switch 202 can electrically connect the output of the power amplifier 201 to a selected transmit filter of the multiplexer 203. The selected transmit filter can be a bandpass filter having a passband corresponding to the frequency of the output signal of the power amplifier 201. The multiplexer 203 can include any suitable number of transmit filters and any suitable number of receive filters. In some applications, the multiplexer 203 may have the same number of transmit filters as the receive filters. In some instances, the multiplexer 203 may have a different number of transmit filters than the receive filters.

As shown in Figure 10A, the intermediate frequency (IF) path includes a power amplifier 204 configured to amplify IF RF signals, a band selection switch 205, and a multiplexer 206. The band selection switch 205 electrically connects the output of the power amplifier 204 to a selected transmit filter of the multiplexer 206. The selected transmit filter can be a bandpass filter having a passband corresponding to the frequency of the output signal of the power amplifier 204. The multiplexer 206 can include any suitable number of transmit filters and any suitable number of receive filters. In some applications, the multiplexer 206 may have the same number of transmit filters as the receive filters. In some instances, the multiplexer 206 may have a different number of transmit filters than the receive filters.

In the illustrated radio frequency system 200, the high-frequency path includes a power amplifier 207 configured to amplify high-frequency radio frequency signals, a band selection switch 208, and a multiplexer 209. The band selection switch 208 can electrically connect the output of the power amplifier 207 to a selected transmit filter of the multiplexer 209. The selected transmit filter can be a bandpass filter having a passband corresponding to the frequency of the output signal of the power amplifier 207. The multiplexer 209 can include any suitable number of transmit filters and any suitable number of receive filters. In some applications, the multiplexer 209 may have the same number of transmit filters as the receive filters. In some instances, the multiplexer 209 may have a different number of transmit filters than the receive filters.

The selector switch 210 can selectively provide radio frequency signals from either the intermediate frequency (IF) or high frequency (HF) path to the dual signaler 176. Therefore, the radio frequency system 200 can process carrier aggregation signals with a combination of low and high frequency bands or a combination of low and IF bands.

Figure 10B is a schematic diagram of an RF system 212 that includes multiple multiplexers in multiple signal paths between the power amplifier and the antenna. RF system 212 is similar to RF system 200 of Figure 10A, except that RF system 212 includes switch multiplexing features. Switch multiplexing can be implemented according to any suitable principles and advantages described herein.

Switching multiplexing enables on-demand multiplexing. Some RF systems can operate in single-carrier mode most of the time (e.g., about 95% of the time) and in carrier aggregation mode for a small portion of the time (e.g., about 5% of the time). Compared to multiplexers that include filters with fixed connections at a common node, switching multiplexing reduces the load in single-carrier mode, allowing the RF system to operate in single-carrier mode most of the time. This load reduction is more significant when a larger number of filters are included in the multiplexer.

In the illustrated RF system 212, multiplexers 213 and 214 are coupled to multiplexer 176 via switch 215. Switch 215 is configured as a multi-closed switch capable of simultaneously operating two or more throws. Simultaneous operation of multiple throws of switch 215 allows for the transmission and/or reception of carrier-aggregated signals. Switch 215 can also operate as a single throw in a single-carrier mode. As illustrated, multiplexer 213 includes multiple duplexers coupled to the respective throws of switch 215. Similarly, the illustrated multiplexer 214 includes multiple duplexers coupled to the respective throws of switch 215. Alternatively, instead of coupling multiple duplexers to each throw of switch 215 as shown in FIG. 10B, one or more individual filters of the multiplexer can be coupled to dedicated throws of switches coupled between the multiplexer and a common node. For example, in some applications, such a switch may have twice the number of throws of the illustrated switch 215.

Switch 215 is coupled between the filter of multiplexer 213 and the common node COM, and between the filter of multiplexer 214 and the common node COM. Figure 10 illustrates that less than all of the filters of the multiplexer can be electrically connected to the common node simultaneously.

In some instances, two or more throws of a switch coupled between a power amplifier and a multiplexer can operate simultaneously. For example, in some embodiments, in RF system 212, two or more throws of band selection switch 205 and/or band selection switch 208 can operate simultaneously. Load losses can occur when multiple throws of the switch simultaneously electrically connect the multiplexer's filters to the power amplifier. Therefore, one or more acoustic filters of the multiplexer may include a series bulk acoustic resonator coupled between a surface acoustic wave resonator and the power amplifier.

Figure 10C is a schematic diagram of the acoustic resonators of a multiplexer 216 according to one embodiment. Multiplexer 216 is similar to multiplexer 130 of Figure 5, except that SAW resonators 132 and 142 are replaced by BAW resonators 217 and 218, respectively. In applications where ports I/O ₁ and I/O _N can be electrically connected to each other, for example, by the simultaneous action of multiple throws of a multi-throw switch, BAW resonators 217 and 218 can reduce the load relative to SAW resonators 132 and 142. As an illustrative example, relative to SAW resonators 132 and 142 of Figure 5, BAW resonators 217 and 218 of Figure 10C can reduce the load when the two throws of the band selection switch 205 of Figure 10B electrically connect BAW resonators 217 and 218 to each other. Any suitable number of BAW resonators can be coupled between the SAW resonators of a filter and the I/O ports (e.g., the input ports of a transmit filter). For example, a series BAW resonator and one or more other series BAW resonators and/or one or more shunt BAW resonators can be coupled between the SAW resonator of the filter and the I/O port. In some instances, the series BAW resonator is coupled only between the surface acoustic wave (SAW) resonators of the multiplexer's transmit filter, and not between the I/O port and the SAW resonator of the multiplexer's receive filter. In some instances, the series BAW resonator is coupled only between the I/O port and the SAW resonator of a subset of the multiplexer's transmit filter, and not between the I/O port and the SAW resonators of the multiplexer's receive filter and one or more other transmit filters.

Figure 11A is a block diagram of a filter assembly 220 with different wafers, which include acoustic resonators for one or more filters according to embodiments described herein. As illustrated, the filter assembly 220 includes SAW wafer 222 and BAW wafer 224 included on a common substrate 226. One or more acoustic filters may include multiple resonators implemented on SAW wafer 222 and BAW wafer 224. BAW wafer 224 may be an FBAR wafer according to some embodiments. Substrate 226 may be a laminated substrate or any other suitable packaging substrate. The resonators of one or more acoustic filters of a multiplexer may be implemented on SAW wafer 222 and BAW wafer 224. The resonators of one or more multiplexers may be implemented on SAW wafer 222 and BAW wafer 224. For example, the resonators of multiple multiplexers may be implemented on SAW wafer 224 and BAW wafer 224.

As an example, a quadplexer can be implemented using a duplexer electrically connected to a common node for bands 25 and 66. In some designs, the band 25 transmit and receive filters can be implemented using BAW resonators to meet performance specifications, and the band 66 transmit and receive filters have been implemented using SAW resonators for cost savings. Based on the principles and advantages described herein, the majority of the resonators in the band 66 transmit and receive filters (e.g., at least 70%, at least 80%, or more) can be implemented using SAW resonators on SAW chip 222. These SAW resonators can be coupled to the common node via series BAW resonators on BAW chip 224. The band 66 transmit and receive filters can be implemented using resonators on BAW chip 224. In some instances, one or more resonators of the band 66 transmit and receive filters can be implemented on SAW chip 222.

As yet another example, according to some embodiments, the duplexer may include: a transmit filter comprising at least one resonator on BAW wafer 224 and a plurality of resonators on SAW wafer 222; and a receive filter comprising at least one resonator on BAW wafer 224 and a plurality of resonators on SAW wafer 222.

According to some embodiments, one or more acoustic filters of the multiplexer can be implemented using resonators on both SAW chip 222 and BAW chip 224, and one or more acoustic filters of the same multiplexer can be implemented using resonators on only one of SAW chip 222 or BAW chip 224.

In some embodiments, different SAW wafers and/or different BAW wafers can be implemented for different frequency ranges. Such different wafers for different frequency ranges may include piezoelectric layers and/or metallization layers of different thicknesses.

Figure 11B is a block diagram of a filter assembly 227 with different wafers, which include acoustic resonators of filters according to embodiments described herein. As illustrated, filter assembly 227 includes SAW wafers 222A and 222B and a BAW wafer 224 included on a common substrate 226. A multiplexer may include acoustic filters comprising resonators implemented on the first SAW wafers 222A and 222B and BAW wafer 224. The multiplexer may also include other acoustic filters comprising resonators implemented on the second SAW wafers 222B and 224. The different SAW wafers 222A and 222B may implement SAW resonators of acoustic filters arranged to filter radio frequency signals within different defined frequency ranges. The multiplexer 20 of Figure 2A can be implemented using filter assembly 227. For example, the SAW resonators of the first transmit filter and the first receiver of the multiplexer 20 can be implemented on the first SAW chip 222A, the SAW resonators of the second transmit filter and the second receive filter of the multiplexer 20 can be implemented on the second SAW chip 222B, and the BAW resonator of each filter of the multiplexer 20 can be implemented on the BAW chip 224. In some other instances (not illustrated), the BAW resonators of the multiplexer 20 can be implemented on two or more BAW chips.

Figure 11C is a block diagram of a filter assembly 229 with different wafers, each wafer including an acoustic resonator of a filter according to an embodiment described herein. As illustrated, the filter assembly 229 includes SAW wafers 222A, 222B, and 222C and a BAW wafer 224, all mounted on a common substrate 226. A multiplexer may include an acoustic filter comprising resonators implemented on the first SAW wafers 222A and 222C and the BAW wafer 224. The multiplexer may also include additional acoustic filters comprising resonators implemented on the second SAW wafers 222B and 224. The multiplexer may also include further acoustic filters comprising resonators implemented on the third SAW wafers 222C and 224. The different SAW wafers 222A, 222B, and 222C may implement SAW resonators of acoustic filters arranged to filter radio frequency signals within different defined frequency ranges.

The multiplexer 70 in Figure 4 can be implemented using filter assembly 229. For example, the first transmit filter and the first receiver of the multiplexer 70 can be implemented on the first SAW chip 222A, the SAW resonators of the second transmit filter and the second receive filter of the multiplexer 70 can be implemented on the second SAW chip 222B, the SAW resonators of the third transmit filter and the third receive filter of the multiplexer 70 can be implemented on the third SAW chip 222C, and the BAW resonator of the multiplexer can be implemented on the BAW chip 224. In some other instances (not illustrated), the BAW resonator of the multiplexer 70 can be implemented on two or more BAW chips.

The filters and multiplexers described herein can be implemented in a wide variety of packaged modules. Some example packaged modules that can implement any suitable principles and advantages of the multiplexers and/or filters described herein will now be described. Figures 12, 13, and 14 are schematic block diagrams of exemplary packaged modules according to some embodiments.

Figure 12 is a schematic block diagram of module 230, which includes a power amplifier 232, a switch 234, and a filter 236 according to one or more embodiments. Module 230 may include a package surrounding the illustrated elements. The power amplifier 232, switch 234, and filter 236 may be arranged on a common package substrate. For example, the package substrate may be a laminated substrate. Switch 234 may be a multi-throw RF switch. Switch 234 may electrically couple the output of power amplifier 232 to a selected filter of filter 236. Filter 236 may include any suitable number of acoustic filters configured as a multiplexer. The acoustic filters of filter 236 may be implemented according to any suitable principles and advantages described herein. Filter 236 may include one or more SAW chips and one or more BAW chips.

Figure 13 is a schematic block diagram of module 240, which includes power amplifiers 242 and 243, switches 244 and 245, and a filter 246 according to one or more embodiments. Module 240 is similar to module 230 of Figure 12, except that module 240 includes an additional power amplifier 243 and an additional switch 245, and the filter 246 is arranged as one or more multiplexers for the signal paths associated with the power amplifiers.

Figure 14 is a schematic block diagram of module 250, which includes power amplifiers 252 and 253, switches 254 and 255, filters 257 and 258 according to one or more embodiments, and an antenna switch 259. Module 250 is similar to module 240 of Figure 13, except that module 250 includes antenna switch 259, which is arranged to selectively couple signals from filter 257 or filter 258 to an antenna node. In Figure 14, filters 257 and 258 are arranged as separate multiplexers.

Figure 15 is a schematic block diagram of a wireless communication device 260 including a filter 263 according to one or more embodiments. The wireless communication device 260 can be any suitable wireless communication device. For example, the wireless communication device 260 can be a mobile phone such as a smartphone. As illustrated, the wireless communication device 260 includes an antenna 261, an RF front-end 262, an RF transceiver 264, a processor 265, and a memory 266. The antenna 261 can transmit RF signals provided by the RF front-end 262. The antenna 261 can provide received RF signals to the RF front-end 262 for processing.

RF front-end 262 may include one or more power amplifiers, one or more low-noise amplifiers, RF switches, receive filters, transmit filters, duplex filters, or any combination thereof. RF front-end 262 can transmit and receive RF signals associated with any suitable communication standard. Any acoustic filters and/or multiplexers described herein can be implemented using filter 263 of RF front-end 262.

RF transceiver 264 can provide RF signals to RF front-end 262 for amplification and/or other processing. RF transceiver 264 can also process RF signals provided by the low-noise amplifier of RF front-end 262. RF transceiver 264 communicates with processor 265. Processor 265 can be a baseband processor. Processor 265 can provide any appropriate baseband processing functions of wireless communication device 260. Memory 266 can be accessed by processor 265. Memory 266 can store any appropriate data of wireless communication device 260.

The embodiments described above have been provided as examples in conjunction with mobile devices such as cellular phones. However, the principles and advantages of these embodiments can be used in any other system or apparatus, such as any uplink cellular device, that can benefit from any of the embodiments described herein. The teachings herein are applicable to a wide variety of systems. While some exemplary embodiments are included, the teachings described herein can be applied to a wide variety of structures. Any principles and advantages discussed herein can be implemented in conjunction with RF circuitry configured to handle signals in the range of about 30 kHz to 300 GHz, for example, in the range of about 450 MHz to 6 GHz.

Many aspects of this application can be implemented in a variety of electronic devices. Examples of electronic devices may include, but are not limited to, consumer electronics, components of consumer electronics such as acoustic resonator chips and/or filter assemblies and/or semiconductor chips and/or packaged radio frequency modules, uplink wireless communication equipment, wireless communication infrastructure, electronic test equipment, etc. Examples of electronic devices may include, but are not limited to, mobile circuits such as smartphones, wearable computing devices such as smartwatches or headphones, telephones, televisions, computer monitors, computers, modems, handheld computers, laptop computers, tablet computers, personal digital assistants (PDAs), microwave ovens, refrigerators, motor vehicles, stereo systems, DVD players, CD players, digital music players such as MP3 players, radios, portable camcorders, cameras, digital cameras, portable storage chips, washing machines, dryers, washer/dryer units, copiers, fax machines, scanners, multi-function peripherals, watches, clocks, etc. Additionally, electronic devices may include unfinished products.

Unless the context otherwise indicates, throughout the specification and claims, the terms "comprising," "including," etc., should be understood in an inclusive sense rather than an exclusive or exhaustive sense (that is, in the sense of "including but not limited to"). The term "coupled," as used generally herein, refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Similarly, the term "connected," as used generally herein, refers to two or more elements that can be directly connected or connected via one or more intermediate elements. Furthermore, the terms "in this document," "above," "below," and similar expressions, when used in this application, should refer to the entire application and not any particular part of it. Where the context permits, the use of singular or plural terms in the above specific embodiments may also include either the plural or the singular, respectively. Regarding the term "or" when referring to a list of two or more items, the term encompasses all of the following interpretations: any item in the list; all items in the list; and any combination of items in the list.

Furthermore, regarding the conditional language used herein, such as “can,” “may,” “possibly,” “can,” “for example,” “like,” “such as,” etc., unless otherwise specifically stated or understood in the context in which they are used, they are generally intended to express that some embodiments include certain features, elements, and/or states, while other embodiments do not include these features, elements, and/or states. Therefore, such conditional language is not generally intended to imply that these features, elements, and/or states are required by any one or more embodiments in any way; or that one or more embodiments necessarily include logic for determining (using or not using designer input or prompts) whether to include or implement these features, elements, and/or states in any particular embodiment.

While some embodiments of the invention have been described, these embodiments are presented by way of example only and are not intended to limit the scope of this application. In fact, the new apparatuses, methods, and systems described herein can be implemented in a wide variety of other forms; and various omissions, substitutions, and changes in the form of the methods and systems described herein can be made without departing from the spirit of this application. For example, although the various blocks are presented in a given arrangement, alternative embodiments may utilize different components and/or circuit topologies to perform similar functions, and some blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these blocks can be implemented in a wide variety of different ways. Any suitable combination of elements and actions of the various embodiments described above can be combined to provide further embodiments. The appended claims and their equivalents are intended to cover such forms and modifications that fall within the scope and spirit of this application.

Claims (40)

1. A multiplexer comprising four acoustic filters coupled to a common node, the four acoustic filters including a first acoustic filter, the first acoustic filter including a plurality of surface acoustic wave resonators and a series volume acoustic resonator coupled between the plurality of surface acoustic wave resonators and the common node, the four acoustic filters including a second acoustic filter, the second acoustic filter including a plurality of second surface acoustic wave resonators and a second series volume acoustic resonator coupled between the plurality of second surface acoustic wave resonators and the common node, wherein the plurality of surface acoustic wave resonators of the first acoustic filter constitute at least 70% of the resonators of the first acoustic filter. 2. The multiplexer according to claim 1, wherein the plurality of surface acoustic wave resonators includes a series surface acoustic wave resonator connected in series with the series bulk acoustic wave resonator. 3. The multiplexer according to claim 1, wherein at least 70% of the resonators of the multiplexer are surface acoustic wave resonators. 4. The multiplexer according to claim 1, wherein the series bulk acoustic resonator is coupled between all surface acoustic wave resonators of the first acoustic wave filter and the common node. 5. The multiplexer according to claim 1, wherein the first acoustic filter further includes a shunt acoustic resonator coupled to the plurality of surface acoustic resonators via the series bulk acoustic resonator. 6. The multiplexer of claim 1 further includes two additional acoustic filters coupled to the common node. 7. The multiplexer according to claim 1, wherein the first acoustic filter includes a split-flow acoustic resonator, and the series bulk acoustic resonator is coupled between the split-flow acoustic resonator and the plurality of surface acoustic resonators. 8. A wireless communication device, comprising: The antenna is configured to receive radio frequency signals; A multiplexer communicating with the antenna, the multiplexer including four acoustic filters coupled to a common node, the four acoustic filters including a first acoustic filter, the first acoustic filter including a plurality of surface acoustic wave resonators and a series volume acoustic resonator coupled between the plurality of surface acoustic wave resonators and the common node, the plurality of surface acoustic wave resonators of the first acoustic filter being at least 70% of the resonators of the first acoustic filter; and A frequency multiplexing circuit coupled between the common node and the antenna. 9. The wireless communication device according to claim 8 further includes an antenna switch coupled between the common node and the antenna. 10. The wireless communication device according to claim 8, wherein the radio frequency signal is a carrier aggregation signal. 11. A filter component, comprising: A first acoustic wave filter coupled to a common node, the first acoustic wave filter including a plurality of surface acoustic wave resonators and a series volume acoustic wave resonator coupled between the plurality of surface acoustic wave resonators and the common node, the plurality of surface acoustic wave resonators realizing at least 70% of the resonators of the first acoustic wave filter; and A second acoustic filter coupled to the common node; The second acoustic filter includes a plurality of second surface acoustic wave resonators and a second series solid acoustic wave resonator coupled between the plurality of second surface acoustic wave resonators and the common node. 12. The filter assembly of claim 11, further comprising at least two additional acoustic filters coupled to the common node. 13. The filter assembly of claim 11, further comprising at least four additional acoustic filters coupled to the common node. 14. The filter assembly of claim 11, wherein the plurality of surface acoustic wave resonators includes a series surface acoustic wave resonator connected in series with the series bulk acoustic wave resonator. 15. The filter assembly of claim 11, wherein the series bulk acoustic resonator is coupled between all surface acoustic resonators of the first acoustic filter and the common node. 16. The filter assembly of claim 11, wherein the plurality of surface acoustic wave resonators comprises at least five resonators. 17. The filter assembly of claim 11, wherein the plurality of surface acoustic wave resonators and the series bulk acoustic wave resonator are implemented on different wafers. 18. The filter assembly of claim 11, further comprising: A third acoustic filter is coupled to the common node. The third acoustic filter includes a plurality of third surface acoustic wave resonators and a third series acoustic wave resonator coupled between the plurality of third surface acoustic wave resonators and the common node. 19. A filter assembly, comprising: A first acoustic filter having a passband and coupled to a common node; and A second acoustic filter coupled to the common node, the second acoustic filter comprising a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the common node, the series acoustic resonator of the second type having a higher quality factor in the passband of the first acoustic filter than the plurality of acoustic resonators of the first type, and the plurality of acoustic resonators of the first type of the second acoustic filter constituting at least 70% of the resonators of the second acoustic filter. 20. The filter assembly of claim 19, wherein the plurality of acoustic resonators of the first type are plurality of surface acoustic wave resonators, and the series acoustic resonators of the second type are bulk acoustic wave resonators. 21. The filter assembly of claim 19, wherein at least two of the plurality of acoustic resonators of the first type are connected in series with a series acoustic resonator of the second type. 22. The filter assembly of claim 19, further comprising a third acoustic filter coupled to the common node and a fourth acoustic filter coupled to the common node. 23. The filter assembly of claim 19, wherein the first acoustic filter comprises a plurality of additional acoustic resonators of the first type and a second type of additional series acoustic resonators coupled between the plurality of additional acoustic resonators of the first type and the common node. 24. A filter component, comprising: A first acoustic filter having a passband and coupled to a common node; and A second acoustic filter coupled to the common node, the second acoustic filter comprising a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the common node, the series acoustic resonator of the second type having a higher quality factor in the passband of the first acoustic filter than the plurality of acoustic resonators of the first type, the plurality of acoustic resonators of the first type constituting at least 70% of the resonators of the second acoustic filter, the plurality of acoustic resonators of the first type being a plurality of non-temperature-compensated surface acoustic wave resonators, and the series acoustic resonator of the second type being a temperature-compensated surface acoustic wave resonator. 25. The filter assembly of claim 24, wherein the second acoustic filter includes a second type of shunt acoustic resonator and a second type of series acoustic resonator coupled between the second type of shunt acoustic resonator and a plurality of first type acoustic resonators. 26. A filter component, comprising: A first acoustic filter having a first passband and coupled to a common node; A second acoustic filter coupled to the common node, the second acoustic filter including a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the common node, wherein the plurality of acoustic resonators of the first type of the second acoustic filter constitute at least 70% of the resonators of the second acoustic filter. A third acoustic filter having a third passband and coupled to a common node; and A fourth acoustic filter with a fourth passband coupled to a common node. The second type of series acoustic resonator has a higher quality factor in the first passband, the third passband, and the fourth passband than the first type of multiple acoustic resonators. 27. The filter assembly of claim 26, wherein the plurality of acoustic resonators of the first type are plurality of surface acoustic wave resonators, and the series acoustic resonators of the second type are bulk acoustic wave resonators. 28. The filter assembly of claim 26, wherein the filter assembly comprises a first wafer and a second wafer, the first wafer comprising a plurality of acoustic resonators of the first type, and the second wafer comprising a series acoustic resonator of the second type. 29. A filter assembly, comprising: A first acoustic filter having a passband and coupled to a common node; and A second acoustic filter coupled to the common node, the second acoustic filter comprising a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the common node, the series acoustic resonator of the second type having a higher quality factor in the passband of the first acoustic filter than the plurality of acoustic resonators of the first type, and the plurality of acoustic resonators of the first type of the second acoustic filter constituting at least 70% of the resonators of the second acoustic filter, the filter assembly comprising a first wafer and a second wafer, the first wafer comprising the plurality of acoustic resonators of the first type, and the second wafer comprising the series acoustic resonators of the second type. 30. The filter assembly of claim 29, wherein the first acoustic filter includes a plurality of additional acoustic resonators of the first type and a second type of additional series acoustic resonator coupled between the plurality of additional acoustic resonators of the first type and the common node. 31. The filter assembly of claim 29, wherein the plurality of acoustic resonators of the first type are plurality of surface acoustic wave resonators, and the series acoustic resonators of the second type are bulk acoustic wave resonators. 32. A multiplexer having multiple acoustic filters, the multiplexer comprising: A first acoustic wave filter coupled to a common node, the first acoustic wave filter comprising a plurality of acoustic wave resonators of a first type and a series acoustic wave resonator of a second type coupled between the plurality of acoustic wave resonators of the first type and the common node, wherein the plurality of acoustic wave resonators of the first type are a plurality of non-temperature-compensated surface acoustic wave resonators, and the series acoustic wave resonator of the second type is a temperature-compensated surface acoustic wave resonator, the plurality of acoustic wave resonators of the first type of the first acoustic wave filter constituting at least 70% of the resonators of the first acoustic wave filter; and Three other acoustic filters, coupled to the common node and each having a corresponding passband, wherein the second type of series acoustic resonator has a higher quality factor in each of the corresponding passbands of the three other acoustic filters than the first type of multiple acoustic resonators. 33. The multiplexer of claim 32, wherein at least one of the three other acoustic filters comprises a plurality of second acoustic resonators of the first type and a second series acoustic resonator of the second type coupled between the plurality of second acoustic resonators of the first type and the common node. 34. The multiplexer of claim 32 further includes an additional acoustic filter coupled to the common node. 35. A method for processing carrier aggregation signals, the method comprising: The carrier aggregation signal is filtered using a first acoustic filter, the first acoustic filter being coupled to an antenna port and having a first passband; the carrier aggregation signal includes a first radio frequency carrier in the first passband and a second radio frequency carrier in the second passband; and The carrier aggregation signal is filtered using a second acoustic filter, which is coupled to the antenna port and has a second passband. The second acoustic filter includes a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the antenna port. The plurality of acoustic resonators of the first type constitute at least 70% of the resonators of the second acoustic filter. The series acoustic resonator of the second type has a lower load loss than the plurality of acoustic resonators of the first type, and the plurality of acoustic resonators of the first type and the series acoustic resonator of the second type are on different wafers. 36. The method of claim 35, further comprising receiving the carrier aggregation signal via an antenna coupled to the antenna port. 37. The method of claim 35, further comprising transmitting the carrier aggregation signal via an antenna coupled to the antenna port. 38. The method of claim 35 further comprises coupling the first acoustic filter and the second acoustic filter to a common node via a multi-throw switch. 39. The method of claim 35, wherein the plurality of acoustic resonators of the first type are plurality of surface acoustic wave resonators, and the series acoustic resonators of the second type are bulk acoustic wave resonators. 40. A method for processing carrier aggregation signals, the method comprising: The carrier aggregation signal is filtered using a first acoustic filter, the first acoustic filter being coupled to an antenna port and having a first passband; the carrier aggregation signal includes a first radio frequency carrier in the first passband and a second radio frequency carrier in the second passband; and The carrier aggregation signal is filtered using a second acoustic filter coupled to the antenna port and having a second passband. The second acoustic filter includes a plurality of acoustic resonators of a first type and a series acoustic resonator of a second type coupled between the plurality of acoustic resonators of the first type and the antenna port. The plurality of acoustic resonators of the first type constitute at least 70% of the resonators of the second acoustic filter. The series acoustic resonator of the second type has a lower load loss than the plurality of acoustic resonators of the first type. The plurality of acoustic resonators of the first type are a plurality of non-temperature-compensated surface acoustic wave resonators, and the series acoustic resonator of the second type is a temperature-compensated surface acoustic wave resonator.