Acoustic resonators with bandwidth-shifting inductors

Abstract

Acoustic resonators with bandwidth-shifting inductors are disclosed. In one aspect, a filter may be formed from a plurality of acoustic resonators and associated inductors. The inductors may be formed such that no capacitors are required to frequency shift a passband of the filter. Further, the inductors may be arranged in a T-arrangement, thereby reducing the space required for the inductors. Multiple stages of resonator structures may be chained together to form a filter with a desired response. In this fashion, a filter may be created with a passband at bandwidths higher than possible with just acoustic resonators without imposing manufacturing requirements related to capacitor formation and without the size penalty of some inductor structures.

Description

ACOUSTIC RESONATORS WITH BANDWIDTH-SHIFTING INDUCTORSPRIORITY APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application Serial No. 63 / 618,017, filed on January 5, 2024, and entitled “ACOUSTIC RESONATORS WITH BANDWIDTH-SHIFTING INDUCTORS,” the contents of which are incorporated herein by reference in its entirety.BACKGROUNDI. Field of the Disclosure

[0002] The technology of the disclosure relates generally to acoustic filters used in communication devices.II. Background

[0003] Computing devices abound in modern society, and more particularly, mobile communication devices have become increasingly common. The prevalence of these mobile communication devices is driven in part by the many functions that are now enabled on such devices. Increased processing capabilities in such devices means that mobile communication devices have evolved from pure communication tools into sophisticated mobile entertainment centers, thus enabling enhanced user experiences. With the advent of the myriad functions available to such devices, there has been increased pressure to provide more bandwidth to send and receive data. Responsive to this pressure, the evolving wireless standards have progressed to ever higher frequencies. While conceptually, these higher frequencies satisfy the need for increased bandwidth, these higher frequencies pose new challenges to the hardware, particularly for filters being used to transmit and receive such signals. Accordingly, there is room for innovation in the filters being designed for use with emerging technologies.SUMMARY

[0004] Aspects disclosed in the detailed description include acoustic resonators with bandwidth-shifting inductors. Tn particular, a filter may be formed from a plurality of acoustic resonators and associated inductors. The inductors may be formed such that no capacitors are required to frequency shift a passband of the filter. Further, the inductors may be arranged in a T-arrangement, thereby reducing the space required for theinductors. Multiple stages of resonator structures may be chained together to form a filter with a desired response. In this fashion, a filter may be created with passband bandwidths higher than possible with just acoustic resonators without imposing manufacturing requirements related to capacitor formation and without the size penalty of some inductor structures.

[0005] In this regard, in one aspect, a filter is disclosed. The filter includes an input node and an output node. The filter also includes a first acoustic resonator serially positioned between the input node and the output node and a T-network of inductors serially positioned between the input node and the output node and electrically parallel to the first acoustic resonator.

[0006] In another aspect, a method of operating a filter is disclosed. The method includes positioning a first acoustic resonator between an input node and an output node, forming a T-network of inductors between the input node and the output node electrically parallel to the first acoustic resonator, and excluding use of capacitors in the filter.

[0007] In another aspect, a communication device is disclosed. The communication device includes a transceiver comprising a filter comprising an input node, an output node, a first acoustic resonator serially positioned between the input node and the output node, and a T-network of inductors serially positioned between the input node and the output node and electrically parallel to the first acoustic resonator; wherein there are no capacitors between the input node and the output node.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a circuit diagram of an exemplary fdter that uses capacitors and inductors;

[0009] Figure 2 is a circuit diagram of an initial approach to provide a filter without capacitors that suffers from size penalties;

[0010] Figure 3A is a circuit diagram of an exemplary II filter formed from acoustic resonators and just a T-shaped inductor circuit to change the passband;

[0011] Figure 3B is an exemplary diagram of an exemplary T-filter formed from acoustic resonators and just a T-shaped inductor circuit to change the passband;

[0012] Figure 4 is a block diagram of a filter formed from building blocks of Figures 3 A and / or Figure 3B ;

[0013] Figure 5 is a flowchart illustrating an exemplary process for forming a filter according to aspects of the present disclosure; and

[0014] Figure 6 is a block diagram of a mobile terminal, which may include the filters of Figures 3 A-4 according to the present disclosure.DETAILED DESCRIPTION

[0015] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

[0016] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element without departing from the scope of the present disclosure. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0017] It will be understood that when an element such as a layer, region, or substrate is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element, or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, no intervening elements are present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referred to as being “over” or extending “over” another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly over” or extending “directly over” another element, no intervening elements are present. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, no intervening elements are present.

[0018] Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe a relationship of one element,layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a," “an,” and “the” are intended to include the plural forms as well unless the context clearly indicates otherwise. It will be further understood that the terms “comprises," “comprising," “includes,” and / or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0020] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0021] In keeping with the above admonition about definitions, the present disclosure uses transceiver in a broad manner. Current industry literature uses transceiver both broadly to refer to a plurality of circuits that send and receive signals. Exemplary circuits may include a baseband processor, an up / down conversion circuit, filters, amplifiers, couplers, and the like coupled to one or more antennas. Likewise, some authors in the industry literature refer to a circuit positioned between a baseband processor and a power amplifier circuit as a transceiver. This intermediate circuit may include the up / down conversion circuits, mixers, oscillators, filters, and the like but generally does not include the power amplifiers. As used herein, the term transceiver is used in the first sense. Where relevant to distinguish between the two definitions, the terms “transceiver chain” and “transceiver circuit” are used respectively.

[0022] Aspects disclosed in the detailed description include acoustic resonators with bandwidth-shifting inductors. In particular, a filter may be formed from a plurality of acoustic resonators and associated inductors. The inductors may be formed such that no capacitors are required to frequency shift a passband of the filter. Further, the inductors may be arranged in a T-arrangement, thereby reducing the space required for the inductors. Multiple stages of resonator structures may be chained together to form a filterwith a desired response. In this fashion, a filter may be created with a passband at bandwidths higher than possible with just acoustic resonators without imposing manufacturing requirements related to capacitor formation and without the size penalty of some inductor structures.

[0023] Before addressing aspects of the present disclosure, a discussion of conventional approaches is provided so that the limitations of such may be compared to the possibilities opened by aspects of the present disclosure. In this regard, Figures 1 and 2 show conventional approaches, and a discussion of aspects of the present disclosure begins below with reference to Figure 3A.

[0024] The use of acoustic resonators for filters is well-known. However, the bandwidth associated with such acoustic resonators is inherently limited by the electromechanical coupling. To overcome this limitation, filters using a combination of inductors (L) and capacitors (C) with the acoustic resonators are used. With the assistance of high-quality acoustic resonators, LC filters attain sharp skirts and have inherently larger bandwidths. In many cases, the acoustic resonators are bulk acoustic wave (BAW), and the resulting filters may also be referred to as BAW-assisted filters. Note that there are also surface acoustic wave (SAW) resonators. Generically, BAW and SAW resonators may be referred to as acoustic wave resonators (and sometimes AW resonators).

[0025] In this regard, Figure 1 is a circuit diagram of a BAW-assisted filter 100 found in U.S. Patent Application Serial No. 18 / 083,285, filed December 16, 2022. The filter 100 has an input node 102 and an output node 104. A first acoustic resonator 106 is positioned serially between the input node 102 and the output node 104. A second acoustic resonator 108 is connected to ground 110 through a ground inductor 112 between a first capacitor 114 and a second capacitor 116. Additional inductors 118, 120, and 122 may form a T-network 124 in parallel with the first acoustic resonator 106.

[0026] Filters such as BAW-assisted filter 100 that use capacitors are known to be sensitive to capacitor variation and may have an insertion loss that is highly dependent on the capacitors having high quality factors. While it is possible to make such high-quality capacitors, the development and integration into filter dies is time-consuming and costly. Accordingly, it may be easier to make a BAW-assisted filter without capacitors. More generally, it may also be easier to use any AW resonator-based filter without capacitors.

[0027] It turns out that such a filter is possible, as illustrated in Figure 2. Specifically, a filter 200 may have an input node 202 and an output node 204. A first acoustic resonator206 is positioned serially between the input node 202 and the output node 204. The input node 202 is also coupled to ground through a first inductor 208 and a second acoustic resonator 210. The output node 204 is also coupled to ground through a second inductor 212 and a third acoustic resonator 214. A third inductor 216 is coupled between the input node 202 and the output node 204 in parallel with the first acoustic resonator 206. This topology is frequently referred to as a n topology.

[0028] The topology of the filter 200 generally requires large inductance values. Large inductance values require large inductors. While devices using these filters that are not size- limited (e.g., desktop computers or the like) may not be concerned about the space consumed by inductors, mobile communication devices face commercial pressure to have increasingly small form factors, and such large inductors are commercially impractical.

[0029] Aspects of the present disclosure provide an alternative to the large inductors while still retaining the ability to avoid the use of high-quality capacitors. Specifically, aspects of the present disclosure recognize that there is a transformation that can create an equivalent T-network from a IT-network. Thus, the filter 200 may be transformed to an equivalent filter 300 illustrated in Figure 3A.

[0030] In this regard, Figure 3A illustrates the filter 300 with a fl-network 302 of acoustic resonators 304, 306, and 308 serially positioned between an input node 310 and an output node 312. That is, a first acoustic resonator 304 is serially positioned between the input node 310 and the output node 312, while second and third acoustic resonators 306, 308 couple input node 310 and output node 312 to ground respectively. A T-network 314 of inductors 316, 318, 320 is serially positioned between the input node 310 and the output node 312 in parallel with the ff-network 302. That is, the first inductor 316 couples an intermediate node 322 to ground, and the second inductor 318 is serially coupled to the third inductor 320 with the intermediate node 322 therebetween.

[0031] The total inductance of the T-network 314 (La+ Lb + Lc) is much smaller than the sum of the inductance of the inductors 208, 212, and 216 (Li + L2 + L3) in the filter 200. For example, La+ Lb + Lcis generally three times smaller than Li + L2 + L3 for equivalent circuits. This makes the topology of filter 300 much more suitable for compact implementation.

[0032] Note that the IT-to-T transformation may also be used on the resonators, resulting in a fdter 350 illustrated in Figure 3B. The T-network 314 remains the same between input node 310’ and output node 312’, but the fl-network 302 of filter 300 isreplaced by a T-network 352 in the filter 350. The T-network includes a first acoustic resonator 354 and a second acoustic resonator 356 in series between the input node 310’ and the output node 312’ with an intermediate node 358 therebetween. The intermediate node 358 is coupled to ground through a third acoustic resonator 360. Again, the inductance of the T-network 314 remains small and thus is easier to implement for compact form factors while still avoiding the use of high-quality capacitors.

[0033] It is possible that a single filter 300 or 350 may not give the desired performance and a series of filter stages may be combined to give a desired performance as better seen in Figure 4. In this regard, Figure 4 illustrates a combined filter 400 that is formed from a plurality of filter stages 402(1 )-402(N), where each filter stage 402(1)- 402(N) may have a topology corresponding to filter 300 or 350.

[0034] There is a corresponding process 500 for forming a filter according to the present disclosure, illustrated in Figure 5. Specifically, the process 500 begins by forming acoustic resonators into a filter 300 or 350 (block 502). The passband of the filter is moved by adding a T-network 314 of inductors with no capacitors (block 504). Optionally filter stages may be chained together to form a filter 300 or 350 (block 506).

[0035] The acoustic resonators (whether SAW, BAW, or the like), according to aspects disclosed herein, may be provided in or integrated into any transceiver device. While the above discussion assumes a wireless transceiver in a mobile communication device, the present disclosure is not so limited. Thus, examples of other transceiver devices, without limitation, include a set-top box, an entertainment unit, a navigation device, a communications device, a fixed location data unit, a mobile location data unit, a global positioning system (GPS) device, a mobile phone, a cellular phone, a smartphone, a session initiation protocol (SIP) phone, a tablet, a phablet, a server, a computer, a portable computer, a mobile computing device, a wearable computing device (e.g., a smartwatch, a health or fitness tracker, eyewear, etc.), a desktop computer, a personal digital assistant (PDA), a monitor, a computer monitor, a television, a tuner, a radio, a satellite radio, a music player, a digital music player, a portable music player, a digital video player, a video player, a digital video disc (DVD) player, a portable digital video player, an automobile, a vehicle component, avionics systems, a drone, and a multicopter.

[0036] With reference to Figure 6, the concepts described above may be implemented in various types of user elements 600, such as mobile terminals, smart watches, tablets, computers, navigation devices, access points, and like wireless communication devices that support wireless communications, such as cellular, wireless local area network(WLAN), Bluetooth, and near field communications. The user elements 600 will generally include a control system 602, a baseband processor 604, transmit circuitry 606, receive circuitry 608, antenna switching circuitry 610, multiple antennas 612, and user interface circuitry 614. In a non-limiting example, the control system 602 can be a field- programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), as an example. In this regard, the control system 602 can include at least a microprocessor s), an embedded memory circuit(s), and a communication bus interface(s). The receive circuitry 608 receives radio frequency signals via the antennas 612 and through the antenna switching circuitry 610 from one or more base stations. A low noise amplifier and a filter of the receive circuitry 608 cooperate to amplify and remove broadband interference from the received signal for processing. Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams using an analog-to-digital converter(s) (ADC).

[0037] The baseband processor 604 processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically comprises demodulation, decoding, and error correction operations. The baseband processor 604 is generally implemented in one or more digital signal processors (DSPs) and ASICs.

[0038] For transmission, the baseband processor 604 receives digitized data, which may represent voice, data, or control information, from the control system 602, which it encodes for transmission. The encoded data is output to the transmit circuitry 606, where a digital-to-analog converter(s) (DAC) converts the digitally encoded data into an analog signal, and a modulator modulates the analog signal onto a carrier signal that is at a desired transmit frequency or frequencies. A power amplifier will amplify the modulated carrier signal to a level appropriate for transmission and deliver the modulated carrier signal to the antennas 612 through the antenna switching circuitry 610 to the antennas 612. The multiple antennas 612 and the replicated transmit and receive circuitries 606, 608 may provide spatial diversity. Modulation and processing details will be understood by those skilled in the art.

[0039] It is also noted that the operational steps described in any of the exemplary aspects herein are described to provide examples and discussion. The operations described may be performed in numerous different sequences other than the illustrated sequences. Furthermore, operations described in a single operational step may actuallybe performed in a number of different steps. Additionally, one or more operational steps discussed in the exemplary aspects may be combined. It is to be understood that the operational steps illustrated in the flowchart diagrams may be subject to numerous different modifications, as will be readily apparent to one of skill in the art. Those of skill in the art will also understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0040] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

AMENDED CLAIMS received by the International Bureau on 14 May 2025 (14.05.2025)What is claimed is:

1. (Previously Presented) A filter comprising: an input node; an output node; a plurality of acoustic resonators comprising a first acoustic resonator and a second acoustic resonator, the plurality of acoustic resonators serially positioned between the input node and the output node; and a T-network of inductors serially positioned between the input node and the output node and electrically parallel to the first acoustic resonator and the second acoustic resonator.

2. (Original) The filter of claim 1 , wherein there are no capacitors between the input node and the output node.

3. (Previously Presented) The filter of claim 2, wherein the second acoustic resonator is serially positioned between the first acoustic resonator and the output node, thereby forming an intermediate node between the first acoustic resonator and the second acoustic resonator.

4. (Original) The filter of claim 3, further comprising a third acoustic resonator coupling the intermediate node to ground.

5. Canceled.

6. (Original) The filter of claim 1, wherein the first acoustic resonator comprises a bulk acoustic wave (BAW) resonator.

7. (Original) The filter of claim 2, wherein the T-network of inductors comprises: a first inductor connected to the input node;a second inductor serially positioned with the first inductor between the input node and the output node, thereby forming an intermediate node therebetween; and a third inductor coupling the intermediate node to ground.

8. (Original) The filter of claim 1, wherein the first acoustic resonator forms part of a first stage and wherein the filter further comprises at least one additional stage.

9. (Original) The filter of claim 8, wherein the at least one additional stage does not have a capacitor therein.

10. (Original) The filter of claim 9, wherein the at least one additional stage comprises a II-network of acoustic resonators and a second T-network of inductors.

11. (Original) The filter of claim 9, wherein the at least one additional stage comprises a T-network of acoustic resonators and a second T-network of inductors.

12. (Previously Presented) A method of forming a filter comprising: positioning a plurality of acoustic resonators between an input node and an output node; forming a T-network of inductors between the input node and the output node, electrically parallel to the plurality of acoustic resonators; and excluding use of capacitors in the filter.

13. (Previously Presented) The method of claim 12, further comprising forming a T- network of acoustic resonators from the plurality of acoustic resonators.

14. Canceled.

15. (Previously Presented) A communication device comprising: a transceiver comprising a filter, the filter comprising:an input node; an output node; a plurality of acoustic resonators serially positioned between the input node and the output node; and a T-network of inductors serially positioned between the input node and the output node and electrically parallel to the plurality of acoustic resonators; wherein there are no capacitors between the input node and the output node.

16. (Previously Presented) The communication device of claim 15, further comprising an intermediate node between a first acoustic resonator and a second acoustic resonator of the plurality of acoustic resonators.

17. (Original) The communication device of claim 16, further comprising a third acoustic resonator coupling the intermediate node to ground.

18. Canceled.

19. (Original) The communication device of claim 15, wherein the T-network of inductors comprises: a first inductor connected to the input node; a second inductor serially positioned with the first inductor between the input node and the output node, thereby forming an intermediate node therebetween; and a third inductor coupling the intermediate node to ground.

20. (Original) The communication device of claim 15, wherein the first acoustic resonator forms part of a first stage and wherein the filter further comprises at least one additional stage.14 May 2025International Bureau of WIPO34 chemin des Colombettes1211 Geneva 20SwitzerlandRe: Patent Application Number: PCT / US2024 / 056481ACOUSTIC RESONATORS WITH BANDWIDTH-SHIFTING INDUCTORSApplicant: Qorvo US, Inc.Our file: 2867-3397-WODear Sir or Madam,STATEMENT UNDER ARTICLE 19(1)Claims 1, 12, and 15 have been amended based on FIG. 3B.Claims 3, 13, and 16 are amended to conform to the amendments to claims 1, 12, and 15, respectively.Claims 5, 14, and 18 are canceled.All other claims remain unchanged.If you have any questions, please do not hesitate to contact me.Very truly yours, / Taylor M. Davenport Reg. No. 42466 / Taylor M. DavenportTMD / nsp tdavenport @ wt-ip.coiEnclosure 919-749-4823

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