Filter with low insertion loss and close channel rejection

Abstract

The present disclosure relates to filters with low insertion loss and near channel rejection. Filters with low insertion loss and near channel rejection and methods of use are disclosed. In one aspect, a multi-stage filter is made with acoustic resonators, the multi-stage filter used to form sections within a given stage. The stages are separated by matching circuits. By relying on stages rather than just sections, the overall insertion loss is kept at an acceptable level while deeply rejecting adjacent channels. Such filter configurations have wide application in wireless systems, especially in Wi-Fi use.

Description

[0001] Cross-reference to related applications

[0002] This application relates to U.S. Provisional Patent Application No. 63 / 785,769, filed April 9, 2025, entitled “Notch Filter with Low Insertion Loss and High Rejection,” and U.S. Provisional Patent Application No. 63 / 831,367, filed June 27, 2025, entitled “Filter with Low Insertion Loss and Near-Channel Rejection,” the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The technology disclosed herein generally relates to filters, and more particularly to filters with low insertion loss and high proximity channel suppression, such as filters that may be needed in multi-band Wi-Fi systems. Background Technology

[0004] In modern society, computing devices are ubiquitous, and mobile or wireless communication devices, in particular, have become increasingly prevalent. The widespread use of these mobile communication devices is partly driven by the many features now enabled on them. The increased processing power in these devices means that mobile communication devices have evolved from mere communication tools into sophisticated mobile entertainment hubs, thereby enhancing the user experience. Various wireless protocols have evolved to serve these mobile or wireless communication devices, including various cellular standards as well as short-range protocols such as Wi-Fi or Bluetooth. Commercial pressures to increase bandwidth have led these standards to provide additional channels, which can be frequency-adapted to existing channels in the electromagnetic spectrum. Finding ways for these channels to coexist has created space for innovation. Summary of the Invention

[0005] The disclosed aspects of the implementation include filters with low insertion loss and near-channel suppression, and methods of using said filters. In particular, aspects of this disclosure contemplate a multi-stage filter made of acoustic resonators, which is used to form segments within a given stage. The stages are separated by matching circuitry. By relying on stages rather than just segments, the overall insertion loss is kept at an acceptable level while deeply suppressing adjacent channels. Such filter profiles have wide applications in wireless systems, especially in Wi-Fi.

[0006] In one aspect, a filter is disclosed. The filter comprises: an input; a first filter section; an intermediate matching circuit, the first filter section being coupled in series between the input and the intermediate matching circuit; a second filter section; and an output, the second filter section being coupled in series between the intermediate matching circuit and the output.

[0007] In another aspect, a wireless communication device is disclosed. The wireless communication device includes: a first transceiver configured to operate at a first frequency; a first antenna coupled to the first transceiver and configured to transmit a first signal from the first transceiver; and a second transceiver configured to operate at a second frequency. The wireless communication device further includes a second antenna coupled to the second transceiver and configured to transmit a second signal from the second transceiver, wherein the second signal from the second antenna is incident on and received by the first antenna; and a filter associated with the first antenna. The filter includes: an input; a first filter section; an intermediate matching circuit, the first filter section being coupled in series between the input and the intermediate matching circuit; a second filter section; and an output, the second filter section being coupled in series between the intermediate matching circuit and the output.

[0008] In another aspect, a method for filtering a signal is disclosed. The method includes: providing a signal at an input; filtering the signal using a first filter segment; performing impedance matching on the filtered signal from the first filter segment using an intermediate matching circuit; filtering a matched signal from the intermediate matching circuit using a second filter segment; and outputting a final signal from the second filter segment. Attached Figure Description

[0009] Figure 1 This is a block diagram of a wireless router that can use adjacent channels;

[0010] Figure 2A This is a circuit diagram of a filter stage made of inductors (L) and capacitors (C);

[0011] Figure 2B This is a circuit diagram of a filter stage made of acoustic resonators;

[0012] Figure 2C It is by Figure 2A A graph showing the filter response versus frequency of a filter made of a 2B stage;

[0013] Figure 3 This is a block diagram of a filter according to aspects of this disclosure;

[0014] Figure 4 yes Figure 3 The circuit diagram of the filter;

[0015] Figure 5 It is a circuit diagram of a more general filter, in which each stage can have multiple segments;

[0016] Figure 6A This is a front perspective view of a acoustic liner on a laminate according to aspects of this disclosure;

[0017] Figure 6B This is a front perspective view of a acoustic liner on a laminate according to another aspect of this disclosure; and

[0018] Figure 7 This is a flowchart illustrating an exemplary process for using a filter according to aspects of this disclosure. Detailed Implementation

[0019] The embodiments described below represent the information necessary to enable those skilled in the art to practice the embodiments and demonstrate the best mode of practice. After reading the following description with reference to the accompanying drawings, those skilled in the art will understand the concepts of this disclosure and will appreciate the application of these concepts, even if not specifically set forth herein. It should be understood that these concepts and applications fall within the scope of this disclosure and the appended claims.

[0020] It should 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 used only to distinguish one element from another. For example, without departing from the scope of this disclosure, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0021] It should be understood that when an element such as a layer, region, or substrate is referred to as "on another element" or "extending to another element," it may be directly on or directly extended to the other element, or an intermediary element may also be present. In contrast, when an element is referred to as "directly on another element" or "directly extending to another element," no intermediary element is present. Similarly, it should be understood that when an element such as a layer, region, or substrate is referred to as "above another element" or "extending above another element," it may be directly above or directly extended above the other element, or an intermediary element may also be present. In contrast, when an element is referred to as "directly above another element" or "extending directly above another element," no intermediary element is present. It will also be understood that when an element is referred to as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or an intermediary element may be present. In contrast, when an element is referred to as "directly connected" or "directly coupled" to another element, no intermediary element is present.

[0022] Relative terms such as “below” or “above” or “upper” or “lower” or “horizontal” or “vertical” may be used herein to describe the relationship of one element, layer or region to another element, layer or region as illustrated in the accompanying drawings. It should be understood that these terms, and those discussed above, are intended to include different orientations of the device other than those depicted in the accompanying drawings.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms “a” and “the” are intended to include the plural forms as well. It should also be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated feature, integral, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0024] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that, unless expressly defined herein, the terms used herein shall be interpreted as having the same meaning as they have in the context of this specification and in the relevant art, and shall not be interpreted in an idealized or overly formal sense.

[0025] Consistent with the statements regarding definitions above, this disclosure uses the term "transceiver" in a broad sense. Current industry literature uses "transceiver" in two ways. The first way broadly refers to a transceiver as multiple circuits that transmit and receive signals. Exemplary circuitry may include a baseband processor coupled to one or more antennas, up / down conversion circuitry, filters, amplifiers, couplers, etc. The second way, used by some authors in industry literature, refers to a circuit positioned between the baseband processor and the power amplifier circuitry as a transceiver. This intermediate circuitry may include up / down conversion circuitry, mixers, oscillators, filters, etc., but typically does not include a power amplifier. As used herein, the term transceiver is used in the first sense. When relating to the distinction between the two definitions, the terms "transceiver chain" and "transceiver circuitry" are used respectively.

[0026] In addition, the extent to which the term “approximately” is used in the claims is defined herein as within five percent (5%).

[0027] The disclosed aspects of the implementation include filters with low insertion loss and near-channel suppression, and methods of using said filters. In particular, aspects of this disclosure contemplate a multi-stage filter made of acoustic resonators, which is used to form segments within a given stage. The stages are separated by matching circuitry. By relying on stages rather than just segments, the overall insertion loss is kept at an acceptable level while deeply suppressing adjacent channels. Such filter profiles have wide applications in wireless systems, especially in Wi-Fi.

[0028] While the majority of the discussion below pertains to bandpass filters, it should be understood that these concepts can also be applied to notch filters, and near-band rejection greater than 60 dB can be achieved without affecting insertion loss. Therefore, whether the filter is considered a bandpass filter with good neighbor channel rejection or a notch filter whose notch corresponds to a neighbor channel, the ultimate goal remains to allow the signal of interest to pass through while suppressing signals or harmonics in nearby neighboring channels.

[0029] Before addressing the various aspects of this disclosure, refer to Figure 1 This provides a brief overview of Wi-Fi routers and some common issues. (Reference) Figures 2A to 2C Provides a discussion of filter terminology. See below for reference. Figure 3 Let us begin to discuss the various aspects of this disclosure.

[0030] in this regard, Figure 1The diagram illustrates a communication environment 100, in which router 102 provides wireless communication to service area 104. Within service area 104, multiple wireless communication devices 106(1) to 106(N) may be present. Generally, wireless communication devices 106(1) to 106(N) may be spaced a distance X from each other, where X is several orders of magnitude larger than the wavelength associated with the operating frequency of router 102. That is, X is typically measured in feet or meters, and the wavelength of interest is measured in inches or centimeters.

[0031] As a concrete example, router 102 may be a Wi-Fi router and therefore may include transceivers 108(1) and 108(2) operating in the 5 GHz and 6 GHz bands defined by the current Wi-Fi standard, respectively. Although not shown, another transceiver may operate in the 2.5 GHz band defined by the Wi-Fi standard. Transceivers 108(1) and 108(2) are coupled to antennas 110(1) and 110(2) via filters 112(1) and 112(2), respectively. Accordingly, commercial pressures require router 102 to be small and inconspicuous. Therefore, antennas 110(1) and 110(2) may be relatively close together (typically spaced a few inches or centimeters apart). This relatively small distance is approximately on the order of wavelength at the frequency of interest.

[0032] Therefore, in operation, when transceivers 108(1) and 108(2) are both communicating with wireless communication devices 106(1) and 106(N) on different channels simultaneously in the 5 GHz and 6 GHz bands (both uplink (UL) and downlink (DL)), cross-coupling may occur between antennas 110(1) and 110(2). That is, a transmission from one of the transceivers 108(1) and 108(2) is transmitted through antenna 110(1) and 110(2), and received at the other antenna 110(1) and 110(2), and is regarded as a received signal by the other transceiver 108(1) and 108(2). This unintended received signal generates noise in the receiving transceivers 108(1) and 108(2). For further clarification, for the purposes of this example, it is assumed that wireless communication device 106(1) operates in the 5 GHz band and wireless communication device 106(2) operates in the 6 GHz band. Although not labeled, wireless communication devices 106(1) and 106(2) have corresponding transceivers equipped with corresponding filters and antennas. However, since wireless communication devices 106(1) and 106(2) operate in only one frequency band at a time, and since X is relatively large, the probability of cross-coupling at either wireless communication device 106(1) or 106(2) is very small.

[0033] The presence of cross-coupling burdens filters 112(1) and 112(2) when transmitting frequencies of interest while blocking unwanted adjacent frequencies. For example, in a Wi-Fi system, filter 112(1) may require approximately 60 dB of suppression for a channel in the 6 GHz band. It should be understood that 60 dB is a lenient guideline for more distant channels where less suppression may be required. This requirement is complicated by the general width of the band (e.g., approximately 1.2 GHz for a 6 GHz band extending from 6 GHz to 7.2 GHz) and the width of individual channels, which ranges from 20 to 320 MHz. Physically, wider channels permeate more of the surrounding spectrum, so lower 6 GHz channels will permeate significantly more of the 5 GHz channel. While Wi-Fi has specific use cases, other standards and protocols may also have adjacent channels that can permeate each other, and although the examples discussed below use Wi-Fi channels, the teachings of this disclosure can be applied to other standards, such as 4G / 5G cellular standards (e.g., the 3GPP N104 band, particularly for 5G standards).

[0034] supply Figures 2A to 2C To help understand filter naming conventions. Specifically, Figure 2A and 2B Filter stages 200A and 200B are shown for use in LC circuits and acoustic filters, respectively. Therefore, Figure 2A The filter stage 200A has an input 202 and an output 204. A first shunt inductor 206 and a series capacitor 208 are coupled to the input 202, and a second shunt inductor 210 and a series capacitor 208 are coupled to the output 204. In effect, the first shunt inductor 206 and the series capacitor 208 define the lower edge of the passband of the filter stage 200A, while the second shunt inductor 210 defines the upper edge. Stage 200A is sometimes referred to as a Π-network because it resembles the Greek letter Π. An equivalent filter stage (but not shown) can be found in a T-network.

[0035] Figure 2B Filter stage 200B is shown. Filter stage 200B has an input 220 and an output 222. A shunt acoustic resonator 224 is coupled to the input 220. A series acoustic resonator 226 is coupled in series between the input 220 and the output 222. The nature of the acoustic resonators allows the second shunt inductor to be omitted.

[0036] In use, filter stages 200A or 200B can have the following characteristics: Figure 2C The frequency response is shown in graph 230. The solid line 232 forms the lower edge, and the dashed line 234 forms the upper edge. As noted, for adjacent channels, the notch suppression 236 should be close to 60 dB, which means that the slope of line 232 should be steep.

[0037] One approach to achieving the desired suppression is to add cascaded filter stages (i.e., multi-stage filters). However, this approach leads to an increase in insertion loss with each additional stage. In particular, the insertion loss at the edges of the passband is affected as the number of stages increases. Therefore, there is still room for improvement in the filter.

[0038] This disclosure provides an improved filter that relies on multiple filter segments rather than strictly on multiple stages. The filter stage is defined by the above examples (i.e., three LC components or two acoustic components), and the authors believe this stage definition is generally accepted in the industry. In contrast, a filter segment is a filter stage with associated matching circuitry. The matching circuitry can be an input matching circuit (i.e., at the input side of the stage) or an output matching circuit (i.e., at the output side of the stage).

[0039] Figure 3 An exemplary multi-segment filter 300 is shown, which can be used for filters 112(1), 112(2). The multi-segment filter 300 includes an input 302 and an output 304. A first filter segment 306 is coupled to the input 302, and a second filter segment 308 is coupled to the output 304. A matching circuit 310 is located in series between the first filter segment 306 and the second filter segment 308. In this example, the first filter segment 306 includes an input matching circuit (not shown), and the second filter segment 308 includes an output matching circuit (also not shown).

[0040] Figure 4 The multi-segment filter 300 is described in more detail below. More specifically, the first filter segment 306 includes an input matching circuit 400 formed by a first shunt inductor 402 and a first series inductor 404. Both the first shunt inductor 402 and the first series inductor 404 are coupled to the input 302, and the first series inductor 404 is positioned in series between the input 302 and the first segment 406. The first segment 406 includes a first shunt acoustic resonator 408 (P indicates parallel connection and is distinguished from "s" for series connection) and a first series acoustic resonator 410 (S indicates series connection).

[0041] Matching circuit 310 includes a second series inductor 412 and a second shunt inductor 414. Second filter section 308 includes an output matching circuit 416 formed by a third shunt inductor 418 and a third series inductor 420. Both the third shunt inductor 418 and the third series inductor 420 are coupled to output 304, and the third series inductor 420 is positioned in series between second section 422 and output 304. Second section 422 includes a second shunt acoustic resonator 424 and a second series acoustic resonator 426.

[0042] Figure 3 and 4The concept can be extended to, for example, Figure 5 The multi-stage, multi-segment filter 500 is shown in the diagram. Specifically, the multi-stage, multi-segment filter 500 includes an input 502 and an output 504. A first multi-stage segment 506 is coupled to a second multi-stage segment 508 via a matching circuit 510. Similar to the multi-segment filter 300, the first multi-stage segment 506 includes an input matching circuit 512 having a first shunt inductor 514 and a first series inductor 516. Likewise, the second multi-stage segment 508 includes an output matching circuit 518 having a second shunt inductor 520 and a second series inductor 522.

[0043] Continue to refer to Figure 5 The first multi-stage segment 506 further comprises multiple segments 524(1) to 524(P), with an additional last shunt acoustic resonator 526 preceding the matching circuit 510. Similarly, the second multi-stage segment 508 also comprises multiple segments 528(1) to 528(Q), with an additional last shunt acoustic resonator 530 preceding the output matching circuit 518. It should be noted that P is not necessarily equal to Q, and the values ​​of the various acoustic resonators within each segment can also vary.

[0044] It should also be noted that there may be cases where the input matching circuits 400 / 512, the output matching circuits 416 / 518, or both are omitted. In such cases, the intermediate matching circuits 310 / 510 can be associated matching circuits and can be associated with both the first and second segments.

[0045] The inductor of the matching circuit can be used as follows Figure 6A The surface mounting device shown or as a component of, for example Figure 6B Conductive traces are provided in the laminated metallization layer associated with the acoustic die shown. Specifically, acoustic die 600 can be positioned on laminated metallization layer 602. Internal metal conductors (not shown) can couple the acoustic die to surface mount devices 604(1) to 604(T). In contrast, acoustic die 610 can be positioned on laminated metallization layer 612, and inductors 614(1) to 614(S) can be positioned on a metal layer within laminated metallization layer 612.

[0046] Figure 7 A flowchart is provided for a process 700 for filtering a signal using a multi-segment filter of this disclosure. Specifically, process 700 begins by providing a signal to input 302 (block 702). The signal is filtered using a first segment (block 704), and impedance matching is performed using matching circuit 310 (block 706). The signal is then filtered using a second filter segment 308 (block 708). The filtered signal is then output at output 304 (block 710).

[0047] While exemplary use cases are considered to be Wi-Fi routers, such as router 100, it should be understood that other systems with cross-coupling between proximity antennas and near-frequency channels can also benefit from this disclosure. Similarly, while Wi-Fi currently has a monolithic approach to allocating channels within the 6 GHz band, there may be times when the band is subdivided and channel overflow exists between different sub-bands of the 6 GHz band. This disclosure will also be used in such cases. Therefore, the Wi-Fi router discussion of this disclosure is intended as illustrative and not limiting.

[0048] It should also be noted that the operational steps described in any of the exemplary aspects herein are described to provide examples and discussion. The described operations may be performed in several different orders other than those shown. Furthermore, the operations described in a single operational step may actually be performed in several different steps. Additionally, one or more operational steps discussed in the exemplary aspects may be combined. It should be understood that those skilled in the art will readily appreciate that the operational steps shown in the flowcharts may undergo numerous different modifications. Those skilled in the art will also understand that information and signals can be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips referred to in the detailed embodiments above may be represented by voltage, current, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0049] The prior description of this disclosure is provided to enable any person skilled in the art to make or use it. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations. Therefore, this disclosure is not intended to be limited to the examples and designs described herein, but should be given the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A filter comprising: enter; First filter section; An intermediate matching circuit, wherein the first filter segment is coupled in series between the input and the intermediate matching circuit; Second filter section; as well as The output, wherein the second filter segment is coupled in series between the intermediate matching circuit and the output.

2. The filter according to claim 1, wherein the first filter segment includes a first filter stage and an associated matching circuit.

3. The filter according to claim 2, wherein the first filter stage comprises a first shunt acoustic resonator and a first series acoustic resonator.

4. The filter of claim 2, wherein the associated matching circuit comprises a first series inductor and a first shunt inductor.

5. The filter of claim 2, wherein the associated matching circuit is located in series with respect to the input before the first filter stage.

6. The filter of claim 5, wherein the second filter segment comprises a second filter stage and a second associated matching circuit.

7. The filter of claim 6, wherein the second associated matching circuit is located in series with respect to the intermediate matching circuit after the second filter stage.

8. The filter according to claim 1, wherein the intermediate matching circuit comprises a matching series inductor and a matching shunt inductor.

9. The filter of claim 1, wherein the filter includes a passband between approximately 6 GHz and 7.2 GHz.

10. The filter of claim 8, wherein the matched series inductor includes a surface mount device.

11. The filter of claim 8, wherein the matched series inductor comprises an inductor coil positioned in a laminated metallization layer.

12. A wireless communication device, comprising: A first transceiver, configured to operate at a first frequency; A first antenna is coupled to the first transceiver and configured to transmit a first signal from the first transceiver; A second transceiver, configured to operate at a second frequency; A second antenna is coupled to the second transceiver and configured to transmit a second signal from the second transceiver, wherein the second signal from the second antenna can be incident on the first antenna and received by the first antenna. as well as A filter, associated with the first antenna, comprising: enter; First filter section; An intermediate matching circuit, wherein the first filter segment is coupled in series between the input and the intermediate matching circuit; The second filter section; and The output, wherein the second filter segment is coupled in series between the intermediate matching circuit and the output.

13. A method for filtering a signal, the method comprising: Provide a signal at the input; The signal is filtered using the first filter segment; The intermediate matching circuit is used to perform impedance matching on the filtered signal from the first filter section; The matching signal from the intermediate matching circuit is filtered using a second filter section; and The final signal is output from the second filter section.

14. The method of claim 13, wherein filtering the signal using the first filter segment includes using a first filter stage and a first associated matching circuit.

15. The method of claim 14, wherein using the first filter stage includes using a first series acoustic resonator and a first shunt acoustic resonator.

16. The method of claim 14, wherein using the first associated matching circuit includes using a first series inductor and a first shunt inductor.

17. The method of claim 13, wherein performing the impedance matching using the intermediate matching circuit comprises using a matching series inductor and a matching shunt inductor.

18. The method of claim 13, wherein filtering the signal comprises generating a passband between approximately 6 GHz and approximately 7.2 GHz.

19. The method of claim 14, wherein filtering the matched signal from the intermediate matching circuit using the second filter segment comprises using the second filter segment and a second associated matching circuit.

20. The method of claim 13, wherein filtering the signal comprises using a multi-stage filter.

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