CWG filter and RU, AU or BS having the same

Abstract

Disclosed are a ceramic waveguide filter, a radio unit, an antenna unit and a base station. According to one embodiment, the ceramic waveguide filter comprises a body (1) made of a ceramic material and having a plurality of resonators, each of which comprises a blind hole (101). The blind holes (101) of two resonators open on a first surface of the body (1) and extend toward an opposite second surface of the body (1). Capacitive coupling between the two resonators is achieved by a coupling structure (201) on / in a substrate (2), to which the body (1) is attached on the second surface side.

Description

Technical Field

[0001] The present disclosure relates generally to components of communication devices, and more particularly to a ceramic waveguide (CWG) filter, a radio unit (RU) or an antenna unit (AU) having the CWG filter, and a base station (BS) having the RU and / or the AU. Background Art

[0002] This section introduces aspects that may be helpful in better understanding the present disclosure. Therefore, the statements in this section should be read in this context and should not be construed as admissions of what is or is not related to the prior art.

[0003] BS is an important part of mobile communication system, which can include RU and AU. Considering installation / fixation / occupancy, smaller size and lighter weight have always been the important evolution direction of base station design, including traditional base stations, street macro base stations, micro base stations, small cell base stations and advanced antenna system (AAS) base stations.

[0004] With the development of the 5th generation (5G) communication, multiple-input multiple-output (MIMO) technology is widely used in sub-6GHz base station products, which requires a large number of filter units (FU) integrated / embedded in AU or RU. Considering the cost and space saving, FU is usually soldered on the radio motherboard, low-pass filter (LPF) board, antenna calibration board or antenna power splitter board, which means that smaller and lighter FU is in great demand.

[0005] In traditional BS solutions, metal cavity FU is the most recommended due to its high quality factor (Q) and power handling performance. For 5G advanced radio systems, power handling requirements become less important, while the size and weight of FU become hot issues. CWG filter is one of the most popular 5G FU solutions due to its competitive Q value, light weight, small size and low cost.

[0006] The CWG filter body is formed of a solid dielectric material such as ceramic coated with a conductive material (e.g., silver). The high dielectric constant of the ceramic reduces the waveguide wavelength, allowing the CWG filter to have a smaller physical size than a conventional cavity filter at a specific resonant frequency. Furthermore, the dielectric cavities / resonators within the body are linked by direct coupling or cross-coupling structures. In the filter topology, inductive coupling (also called positive coupling) and capacitive coupling (also called negative coupling) are usually used to achieve resonator coupling. Negative / capacitive coupling is particularly important for achieving cross coupling.

[0007] Currently, most CWG filters achieve negative / capacitive coupling through deeper blind holes or blind slots on the ceramic body, which is not convenient for coupling value / strength control, inflexible in coupling position setting, increases cost, and reduces near-band attenuation performance due to harmonic spurious. Summary of the invention

[0008] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0009] It is an object of the present disclosure to provide an improved solution for introducing capacitive cross-coupling in a CWG filter.

[0010] According to a first aspect of the present disclosure, a CWG filter is provided. The CWG filter comprises a body made of ceramic and having a plurality of resonators, each of which comprises a blind hole. The blind holes of two resonators open at a first surface of the body and extend toward an opposite second surface of the body. Capacitive coupling between the two resonators is achieved by a coupling structure on / in a substrate, to which the body is attached on the second surface side.

[0011] In one embodiment of the present disclosure, metallized grooves are provided on the second surface of the body at positions corresponding to the two resonators, and the coupling structure is connected to the metallized grooves via a pad.

[0012] In one embodiment of the present disclosure, metal pins are provided on the second surface of the main body at positions corresponding to the two resonators, and the coupling structure is connected to the main body by means of the metal pins.

[0013] In one embodiment of the present disclosure, pads are provided on the second surface of the body at positions corresponding to the two resonators, and the coupling structure is connected to the body via the pads.

[0014] In one embodiment of the present disclosure, the substrate is also a part of the CWG filter, and the substrate may be a printed circuit board (PCB) or a plastic board on which a coupling structure is formed.

[0015] According to a second aspect of the present disclosure, there is provided a radio unit including the CWG filter according to the first aspect, and a substrate to which a main body of the CWG filter is attached.

[0016] In one embodiment of the present disclosure, the substrate is a radio motherboard or an LPF board.

[0017] In an embodiment of the present disclosure, the coupling structure is a transmission line on / in a substrate, a parallel coupler, an interdigital coupler, or a broadside stripline coupler.

[0018] In one embodiment of the present disclosure, the substrate is made of plastic, and the coupling structure is a metal layer integrally formed on the substrate by plating on plastic (POP).

[0019] According to a third aspect of the present disclosure, there is provided an antenna unit including the CWG filter according to the first aspect, and a substrate to which a main body of the CWG filter is attached.

[0020] In one embodiment of the present disclosure, the substrate is an antenna calibration board or an antenna power splitter board.

[0021] In one embodiment of the present disclosure, the coupling structure is a transmission line on / in a substrate, a parallel coupler, an interdigital coupler, or a broadside stripline coupler.

[0022] In one embodiment of the present disclosure, the substrate is made of plastic, and the coupling structure is a metal layer integrally formed on the substrate through POP.

[0023] According to a fourth aspect of the present disclosure, there is provided a base station comprising the radio unit according to the second aspect and / or the antenna unit according to the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and other objects, features and advantages of the present disclosure will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

[0025] Figure 1 shows a CWG filter of one embodiment of the present disclosure viewed from above, and a substrate to which the body of the CWG filter is attached;

[0026] Figure 2 Shows from Figure 1 A CWG filter tilted toward the upper side;

[0027] Figure 3 It is along Figure 1 and 2 A cross-sectional view of the CWG filter taken along line AA' shown;

[0028] Figure 4 is a bottom view of the main body of the CWG filter according to this embodiment.

[0029] Figure 5 is a schematic diagram illustrating a first example of a coupling structure on a substrate;

[0030] Figure 6is a schematic diagram illustrating a second example of a coupling structure;

[0031] Figure 7 is a schematic diagram illustrating a third example of a coupling structure;

[0032] Figure 8 is a schematic diagram illustrating a fourth example of a coupling structure;

[0033] Fig. 9 is a schematic diagram illustrating a topological structure of a CWG filter according to the embodiment;

[0034] Fig.10 is a diagram illustrating a frequency response curve of the CWG filter according to this embodiment. DETAILED DESCRIPTION

[0035] Embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the present disclosure, rather than to imply any limitation on the scope of the present disclosure. Reference to features, advantages or similar language throughout this specification does not mean that all features and advantages that can be implemented by the present disclosure should be in or present in any single embodiment of the present disclosure. On the contrary, the language related to features and advantages should be understood to mean that the specific features, advantages or characteristics described in conjunction with the embodiments are included in at least one embodiment of the present disclosure. In addition, the features, advantages and characteristics described in the present disclosure can be combined in one or more embodiments in any suitable manner. Those skilled in the relevant art will recognize that the present disclosure can be practiced without one or more specific features or advantages of a specific embodiment. In other cases, it can be recognized in certain embodiments that other features and advantages that may not be present in all embodiments of the present disclosure.

[0036] In general, all terms used in this article should be interpreted according to their common meanings in the relevant technical field, unless different meanings are clearly given in the context of its use and / or different meanings are implied from the context of its use. Unless clearly stated otherwise, all references to one / an / the element, equipment, parts, devices, steps, etc. should be openly interpreted as referring to at least one instance of the element, equipment, parts, devices, steps, etc. As long as it is suitable, any feature of any embodiment disclosed herein can be applied to any other embodiment. Similarly, any advantage of any embodiment can be applied to any other embodiment, and vice versa. Other purposes, features and advantages of the attached embodiments will be apparent from the following description.

[0037] Figure 1 A CWG filter according to one embodiment of the present disclosure is shown when viewed from an upper side of the CWG filter. Figure 2 is from Figure 1 It should be noted that in Figure 1 and Figure 2 In the drawings, some components which are not actually visible are also shown in order to illustrate their relative positions with respect to other components. Figure 3 It is along Figure 1 and Figure 2 A cross-sectional view of the CWG filter taken along line AA' is shown.

[0038] The CWG filter according to this embodiment includes a main body 1 made of a ceramic material. The surface of the main body 1 is covered with a conductive layer. The conductive layer may be a metallization layer, for example, formed by electroplating a metal on the surface of the main body 1. The metal may be silver or another metal that meets specific requirements.

[0039] In the illustrated embodiment, the body 1 has six, i.e., first to sixth resonators or resonant cavities. Each resonator includes a blind hole 101. Although the blind hole 101 is shown as having a circular cross-section, the present disclosure is not limited thereto. For example, the cross-section of the blind hole 101 may be rectangular, elliptical, or any other shape. As will be appreciated by those skilled in the art, each blind hole 101 may be used to tune the resonant frequency of the corresponding resonator.

[0040] In the illustrated embodiment, six blind holes 101 are all disposed on the top surface of the main body 1. In other words, each blind hole 101 opens on the top surface of the main body 1 and extends toward the bottom surface of the main body 1. In another embodiment, some blind holes 101 may open on the bottom surface of the main body 1 and extend toward the top surface of the main body 1. The blind holes 101 may have the same or different depths, i.e., the dimensions in the direction in which the blind holes extend. The depth of each blind hole 101 may be set according to a specific application scenario in order to obtain a desired resonant frequency.

[0041] Further, the blind hole 101 is provided with a conductive layer, which is formed, for example, by electroplating metal on the bottom and wall of the blind hole 101. For example, by removing a portion of the conductive layer covering the bottom and / or wall of the corresponding blind hole 101, the resonant frequency of each resonator can be tuned.

[0042] At the central portion of the body 1, a plurality of through-channels 102 are provided, which extend from the top surface of the body 1 to the bottom surface thereof. The through-channels 102 serve as a partition wall between two adjacent resonators, which helps to adjust the coupling value between the two adjacent resonators. The through-channels 102 may take any suitable shape in the cross section of the body 1. For example, Figure 1 As shown, a strip-shaped channel is provided between the first resonator and the sixth resonator, and a cross-shaped channel is provided to isolate the second to fifth resonators.

[0043] In another embodiment, two adjacent resonators may be coupled to each other through a through slot that penetrates from the top surface of the body 1 to the bottom surface thereof.

[0044] The body 1 is provided with a pair of input and output ports 103 on its bottom surface. Signals can be input via the input port and can be output via the output port. The positions of the pair of input and output ports 103 correspond to the positions of the two resonators. In the illustrated embodiment, the input and output ports 103 are located below the first and sixth blind holes 101. In another embodiment, the input and output ports 103 may be located below other blind holes 101. In yet another embodiment, the input and output ports 103 may be provided on the side surface of the body 1.

[0045] In use, the CWG filter is generally arranged on and supported by a substrate 2. The substrate 2 may be a PCB. In one embodiment, the CWG filter is integrated / embedded in a radio unit, and the substrate 2 may be a radio motherboard or an LPF board of the radio unit. In another embodiment, the CWG filter is integrated / embedded in an antenna unit, and the substrate 2 may be an antenna calibration board or a power splitter board of the antenna unit.

[0046] In the illustrated embodiment, the substrate 2 is placed below the body 1 of the CWG filter, and the body 1 is attached to the substrate 2 at the bottom side of the body 1. For example, the body 1 can be soldered to the substrate 2 through the pads, and the body 1 and the substrate 2 are commonly grounded.

[0047] According to the present disclosure, the substrate 2 is provided with a coupling structure 201. Figure 3 It can be clearly seen that the coupling structure 201 is used for two resonators in the main body 1 - for example Figure 1 and Figure 2 Capacitive coupling is created between the second and fifth resonators shown.

[0048] To achieve capacitive coupling, Figure 1 and Figure 2 Each of the second and fifth resonators in the embodiment is provided with a metallized groove 104 on the bottom surface of the body 1. Figure 4 It can be clearly seen that the Figure 4 1 is a bottom view of the main body 1. The metallized groove 104 is located below the corresponding blind hole 101, and its diameter is smaller than the diameter of the blind hole 101. The coupling structure 201 has two connecting parts, each of which is connected to the metallized groove 104 via a pad 105.

[0049] like Figure 1As shown, the center of the metallized groove 104 does not have to coincide with the center of the corresponding blind hole 101. The capacitive coupling value can be controlled or optimized by changing the position of the metallized groove 104 (or in other words, the connection point of the coupling structure 201 and the body 1). In addition, the capacitive coupling value can be optimized by changing the length and / or width of the coupling structure 201.

[0050] In another embodiment, Figure 1 and Figure 2 Each of the second and fifth resonators in the embodiment may be provided with a metal pin on the bottom surface of the body 1. The metal pin may be located below the corresponding blind hole 101, and its diameter may be smaller than the diameter of the blind hole 101. The two connection parts of the coupling structure 201 may be connected to the metal pin.

[0051] In another embodiment, Figure 1 and Figure 2 Each of the second and fifth resonators in the embodiment may be provided with a pad on the bottom surface of the body 1, the pad being connected to the substrate via, for example, a pad on the substrate. The pad on the bottom surface of the body 1 may be located below the corresponding blind hole 101. In other words, the pad is omitted in the present embodiment. Figures 1 to 4 Metallization slots 104 are shown.

[0052] In yet another embodiment, the capacitive coupling may be different from Figure 1 and Figure 2 The second and fifth resonators shown are generated between the other two resonators.

[0053] The coupling structure 201 can be implemented in a variety of configurations. For example, the coupling structure 201 can be implemented in a variety of configurations. Figure 5 The transmission line shown in Figure 6 The parallel coupler shown in Figure 7 The interdigital coupler shown or Figure 8 The configurations of transmission lines, parallel couplers, interdigital couplers and broadside stripline couplers are well known to those skilled in the art, so the related description is omitted.

[0054] Fig. 9 It's a picture. Figure 1 Schematic diagram of the topology of the CWG filter shown in FIG. The numbers 01, 02, 03, 04, 05 and 06 in the circles correspond to the first to sixth resonators of the CWG filter, respectively.

[0055] A direct coupling k12 is provided between the first resonator 01 and the second resonator 02. A direct coupling k23 is provided between the second resonator 02 and the third resonator 03. A direct coupling k34 is provided between the third resonator 03 and the fourth resonator 04. A direct coupling k45 is provided between the fourth resonator 04 and the fifth resonator 05. A direct coupling k56 is provided between the fifth resonator 05 and the sixth resonator 06. A cross coupling k16 is provided between the first resonator 01 and the sixth resonator 06. The direct coupling k12, k23, k34, k45, k56 and the cross coupling k16 are positive / inductive couplings that can be provided by conducting through channels, slots, openings and / or holes, which are well known to those skilled in the art.

[0056] A cross coupling k25 is provided between the second resonator 02 and the fifth resonator 05. The cross coupling K25 is a capacitive / negative coupling provided by the coupling structure 201 on / in the substrate 2. The capacitive coupling value of the cross coupling K25 may be optimized as described above.

[0057] Fig.10 It's a picture. Figure 1 The frequency response curve of the six-pole CWG filter is shown in FIG. Fig.10 As shown, the CWG filter has a passband indicated by 020. A pair of transmission zeros 021 are generated on the low side of the passband 020. Another pair of transmission zeros 022 are generated on the high side of the passband 020. The frequency positions of the transmission zeros 021, 022 can be adjusted by optimizing the cross-coupling value.

[0058] In the above embodiment, the CWG filter has six resonators and therefore has six poles. It is easy for those skilled in the art to understand that the number of resonators or poles is not limited to six, and the CWG filter according to other embodiments of the present disclosure may have the same number of resonators or poles as those of the embodiment of the present disclosure. Figure 1 Different topologies are shown. Furthermore, any resonator may include two or more blind holes.

[0059] In the above embodiment, the substrate 2 is a PCB. The coupling structure 201 can be designed on the surface of the PCB or on the inner layer of the PCB. Figure 8 The broadside stripline coupler shown is designed on the surface and inner layers of the substrate. In addition, the present disclosure is not limited to PCB. For example, the substrate 2 can be made of plastic, and the coupling structure 201 can be a metal layer integrally formed on the substrate 2 through POP.

[0060] Based on the above embodiments, the CWG filter may include a ceramic body and a substrate in which / on which a coupling structure is formed. The CWG filter may be embedded not only in a radio unit or an antenna unit of a base station, but also in other electronic devices that may use the CWG filter.

[0061] In the above-described embodiment, the body 1 of the CWG filter is formed of a large block of ceramic material. However, the present disclosure is not limited thereto. For example, the body 1 of the CWG filter may include two ceramic blocks stacked one above the other.

[0062] Advantages of the CWG filter according to an embodiment of the present disclosure will be described below.

[0063] The filter optimization goal is always to achieve in-band and out-of-band performance at the minimum filter order or number of filter poles. The number of filter resonators determines and is actually equal to the number of poles. At the same filter order, the number and strength of the filter transmission zeros generated by the cross-coupling has a great influence on the out-of-band attenuation performance of the filter.

[0064] Capacitive coupling is more difficult to achieve and control in CWG filters than in traditional metal cavities due to their small size and solid ceramic block structure. Existing CWG filters use deep blind holes or slots to reverse the field to achieve capacitive coupling, which is not convenient in terms of coupling value / strength control, inflexible in coupling position setting, and also increases cost, and reduces near-band attenuation performance due to harmonic spurs.

[0065] In contrast, according to an embodiment of the present disclosure, capacitive coupling is achieved through a coupling structure 201 on a substrate 2 to which the body 1 of the CWG filter is attached. The coupling structure 201 couples the electric field energy of one resonator of the CWG filter to the electric field energy of another resonator, thereby achieving capacitive coupling between the two resonators.

[0066] According to the embodiments of the present disclosure, the capacitive coupling value / strength can be controlled or optimized by changing the length, width, shape and / or position of the coupling structure 201. It is easier to lay out or shape the coupling structure 201 on / in the substrate 2. Therefore, compared with the existing deep blind hole / groove solutions, capacitive coupling can be implemented more flexibly and the filter topology can be formed more effectively. In addition, the accuracy of the capacitive coupling value is much better than the existing blind hole / groove solutions, which enables the CWG filter to have better production consistency.

[0067] In addition, the CWG filter according to the embodiment of the present disclosure can not only achieve better out-of-band attenuation performance, but also is beneficial to near-band harmonic spurious and in-band insertion loss.

[0068] In a preferred embodiment of the present disclosure, the substrate 2 on which the coupling structure 201 is provided is a radio motherboard or LPF board of a radio unit, or an antenna calibration board or a power splitter board of an antenna unit, depending on the floor plan of the base station product. By reusing such an existing PCB to achieve capacitive coupling, no additional cost is added.

[0069] The present disclosure also relates to a radio unit or an antenna unit comprising the CWG filter described above, and a base station comprising the radio unit and / or the antenna unit.

[0070] References in this disclosure to "one embodiment," "another embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment necessarily includes the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is considered to be within the knowledge of those skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments (whether or not explicitly described).

[0071] 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 only used to distinguish between the elements. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as 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 enumerated terms.

[0072] The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an", and "the" are intended to also include plural forms unless the context clearly indicates otherwise. It should be further understood that the terms "include", "have", "comprise" refer to the presence of the features, elements and / or parts when used herein, but do not exclude the presence or addition of one or more other features, elements, parts and / or their combinations. The term "connection" used herein covers direct and / or indirect connections between two elements.

[0073] The present disclosure includes any novel feature or combination of features disclosed herein, whether explicitly disclosed or any generalization thereof. When read in conjunction with the accompanying drawings, various modifications and adjustments to the aforementioned exemplary embodiments of the present disclosure will be apparent to those skilled in the relevant art from the foregoing description. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of the present disclosure.

Claims

1. A ceramic waveguide filter, comprising a body (1) made of ceramic and having a plurality of resonators, each resonator comprising a blind hole (101), the blind holes (101) of two resonators opening on a first surface of the body (1) and extending toward an opposite second surface of the body (1), in, The capacitive coupling between the two resonators is achieved by a coupling structure (201) on / in a substrate (2), to which the body (1) is attached at the second surface side.

2. The ceramic waveguide filter according to claim 1, in, Metallized grooves (104) are provided on the second surface of the body (1) at positions corresponding to the two resonators, and the coupling structure (201) is connected to the metallized grooves (104) via a pad (105).

3. The ceramic waveguide filter according to claim 1, in, Metal pins are provided on the second surface of the main body (1) at positions corresponding to the two resonators, and the coupling structure (201) is connected to the main body (1) by means of the metal pins.

4. The ceramic waveguide filter according to claim 1, in, Pads are provided on the second surface of the body (1) at positions corresponding to the two resonators, and the coupling structure (201) is connected to the pads.

5. The ceramic waveguide filter according to any one of claims 1 to 4, in, The ceramic waveguide filter further comprises the substrate (2), which is a printed circuit board or is made of plastic, and on which the coupling structure (201) is formed.

6. A radio unit comprising the ceramic waveguide filter according to any one of claims 1 to 5, and the substrate (2) to which the main body (1) of the ceramic waveguide filter is attached.

7. The radio unit according to claim 6, in, The substrate (2) is a radio motherboard or a low-pass filter board.

8. A radio unit according to claim 6 or 7, in, The coupling structure (201) is a transmission line, a parallel coupler, an interdigital coupler or a broadside stripline coupler on / in the substrate (2).

9. A radio unit according to any one of claims 6 to 8, in, The substrate (2) is made of plastic, and the coupling structure (201) is a metal layer integrally formed on the substrate (2) by electroplating on the plastic.

10. An antenna unit comprising the ceramic waveguide filter according to any one of claims 1 to 5, and the substrate (2) to which the main body (1) of the ceramic waveguide filter is attached.

11. The antenna unit according to claim 10, in, The substrate (2) is an antenna calibration board or an antenna power division board.

12. The antenna unit according to claim 10 or 11, in, The coupling structure (201) is a transmission line, a parallel coupler, an interdigital coupler or a broadside stripline coupler on / in the substrate (2).

13. The antenna unit according to any one of claims 10 to 12, in, The substrate (2) is made of plastic, and the coupling structure (201) is a metal layer integrally formed on the substrate (2) by electroplating on the plastic.

14. A base station comprising a radio unit according to any one of claims 6 to 9 and / or an antenna unit according to any one of claims 10 to 13.

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