LTCC filter and terminal equipment

Abstract

The invention discloses an LTCC filter and terminal equipment. The LTCC filter comprises a ceramic body, a bottom electrode arranged on the bottom surface of the ceramic body, and a first capacitor structure, a second capacitor structure and a third capacitor structure which are arranged in the ceramic body. Wherein the first capacitor structure is connected to the feed electrode at the bottom, the second capacitor structure is connected to the first signal electrode and at least partially coincides with the projection of the first capacitor structure in the vertical direction to form first capacitive coupling so as to support a first frequency band, and the third capacitor structure is connected to the second signal electrode and at least partially coincides with the projection of the second capacitor structure in the vertical direction to support a second frequency band. The first capacitor structure and the second capacitor structure are arranged at intervals to form second capacitive coupling, thereby supporting a second frequency band. Through the design of combining vertical coincidence coupling and lateral interval coupling, while miniaturization of the device is realized, stable shunting and independent tuning of dual-band signals can be realized, mutual interference between two bands is avoided, and thus improvement of isolation is facilitated.

Description

Technical Field

[0001] This invention relates to the field of communication antenna technology, and in particular to a patch LTCC filter and terminal equipment. Background Technology

[0002] In terminals with extremely limited internal space, such as smartphones and wearable devices, RF front-end modules not only need to support multiple communication frequency bands (such as 2.4GHz and 5GHz), but also must meet miniaturization design requirements. Low-temperature co-fired ceramic (LTCC) technology, with its advantages of high dielectric constant, low loss, ability to fabricate three-dimensional structures, and ease of system-level packaging, has become an important solution for achieving antenna miniaturization and integration.

[0003] However, existing LTCC dual-band antennas still have limitations. Current mainstream solutions typically employ multi-layer patch stacking or single-patch multimode excitation. Multi-layer stacking often requires a large number of ceramic layers, leading to complex manufacturing processes and high costs, and strong electromagnetic coupling can easily occur between radiating patches of different frequency bands. While single-patch multimode solutions have a simpler structure, they struggle to simultaneously achieve both radiation performance and isolation across two frequency bands. Summary of the Invention

[0004] This application discloses an LTCC filter and terminal device that can achieve stable splitting and tuning of dual-band signals while realizing miniaturization, effectively avoiding mutual interference between the two bands, ensuring high isolation, and flexibly adjusting the resonant frequency of the antenna.

[0005] To achieve the above objectives, in a first aspect, this application discloses an LTCC filter, comprising: The ceramic body includes a top surface and a bottom surface along the first direction; A bottom electrode is disposed on the bottom surface, and the bottom electrode includes a feed electrode, a first signal electrode, and a second signal electrode disposed at intervals. A first capacitor structure is disposed within the ceramic body, and the first capacitor structure is electrically connected to the feed electrode; A second capacitor structure is disposed within the ceramic body. The second capacitor structure is electrically connected to the first signal electrode. The projections of the second capacitor structure and the first capacitor structure in the first direction at least partially overlap to form a first capacitive coupling to support the first frequency band. A third capacitor structure is disposed within the ceramic body and connected to the second signal electrode. The third capacitor structure is spaced apart from the first capacitor structure to form a second capacitive coupling to support the second frequency band. The first frequency band and the second frequency band are different frequency bands.

[0006] As an optional implementation, the second capacitor structure and the third capacitor structure are respectively disposed on both sides of the first capacitor structure along the second direction, and the third capacitor structure and the first capacitor structure are spaced apart along both the first direction and the second direction; The second direction intersects with the first direction.

[0007] The second and third capacitor structures are respectively positioned on either side of the first capacitor structure, which serves as a common power supply unit, along a second direction (e.g., the length direction of the ceramic body). By arranging capacitor structures that process different frequencies at opposite ends of the first capacitor structure, the spatial distance between the resonant circuits of the first and second frequency bands is effectively increased. This significantly reduces electromagnetic coupling and crosstalk between the two frequency bands, thereby achieving isolation between the two frequency bands within the same miniature package. This is beneficial for improving the dual-frequency interference problem commonly encountered in compact designs.

[0008] Furthermore, along the first direction, the third capacitor structure does not overlap with the first capacitor structure, and along the second direction (horizontal direction), they also maintain a certain distance. This arrangement, maintaining spacing both in height and in the plane, helps control the coupling amount between the third and first capacitor structures, thus avoiding the inability to match the requirements of the second frequency band due to excessive coupling capacitance. Therefore, the third capacitor structure utilizes the edge electric field for weak coupling, which is beneficial for signal feed and impedance matching in the second frequency band.

[0009] As an optional implementation, the first capacitor structure has a first side and a second side opposite to each other along the second direction, a portion of the second capacitor structure is located on the first side, and at least a portion of the second capacitor structure extends along the second direction to the second side or beyond the second side so as to coincide with the projection of the first capacitor structure in the first direction, and the third capacitor structure is disposed on the second side, and the third capacitor structure is spaced apart from the second capacitor structure in both the first direction and the second direction.

[0010] The first capacitor structure has a first side and a second side opposite to each other along the second direction. The second capacitor structure is not limited to a single region; part of it is located on the first side, while another part extends along the second direction, crossing the central region of the first capacitor structure and extending to or beyond the second side. Thus, the second capacitor structure and the first capacitor structure have a large area of ​​overlapping projection in the first direction, thereby forming a larger coupling capacitance, allowing the second capacitor structure to support a lower frequency in the first frequency band. Simultaneously, a third capacitor structure is disposed on the second side, spaced apart from both the first and second capacitor structures. In this way, the third capacitor structure and the first capacitor structure achieve weak coupling through this edge electric field, allowing the third capacitor structure to support a higher frequency in the second frequency band. In other words, this arrangement, while supporting different frequency bands, also reduces electromagnetic coupling and signal crosstalk between the two frequency bands by arranging capacitor structures for different frequencies at opposite ends of the first capacitor structure, thus helping to improve the problem of dual-frequency interference.

[0011] As an optional implementation, the third capacitor structure includes multiple layers of third capacitor sheets that are spaced apart and electrically connected to each other along the first direction, wherein one layer of the third capacitor sheet is located on the same layer as the first capacitor structure in the first direction.

[0012] To achieve the capacitance required for high-frequency resonance within a relatively small ceramic body while maintaining a distance from the first capacitor structure, the third capacitor structure employs a stacked design with multiple layers of capacitor sheets spaced apart and connected in parallel along the first direction. This multi-layer stacked design can increase capacitance density by increasing the surface area of ​​the electrodes, and by controlling that a specific layer of capacitor sheet is on the same plane as the first capacitor structure, the coupling boundary between the two can be better defined.

[0013] As an optional implementation, the second capacitor structure includes multiple layers of second capacitor sheets that are spaced apart and electrically connected to each other along the first direction, wherein one layer of the second capacitor sheets is located on the same layer as the first capacitor structure in the first direction, and another layer of the second capacitor sheets is located at least partially on one side of the first capacitor structure along the first direction so as to at least partially overlap with the projection of the first capacitor structure in the first direction.

[0014] The second capacitor structure employs a design that combines vertical overlapping coupling and edge coupling. The second capacitor structure consists of multiple layers of capacitor plates spaced apart along the first direction. These capacitor plates are electrically connected to each other, collectively forming a large-area induction electrode.

[0015] Simultaneously, the second capacitor layer in the second capacitor structure is configured to at least partially cover the area where the first capacitor structure is located on its projection along the first direction. This directly overlapping design provides the capacitance value required for the resonance of the first frequency circuit. Furthermore, through this vertically overlapping coupling between the second and first capacitor structures, and the edge coupling between the third and first capacitor structures, the second capacitor structure can effectively induce energy from the first capacitor structure, thereby enabling the LTCC filter to have a better return loss valley.

[0016] As an optional implementation, the second capacitor structure and / or the third capacitor structure further includes a plurality of connecting conductors, and the second capacitor sheet and / or the third capacitor sheet are provided with through holes, and the connecting conductors pass through the through holes along the first direction to connect two adjacent second capacitor sheets or two adjacent third capacitor sheets; The second capacitor and / or the third capacitor are also electrically connected to the corresponding signal electrode via the connecting conductor.

[0017] Connecting conductors penetrate the ceramic dielectric layer, electrically paralleling the multilayer capacitor sheets to create a low-impedance transmission channel. This vertical interconnection not only ensures the consistency of potential among the layers but also acts as a mechanical reinforcing rib, improving the delamination or warping phenomena caused by the mismatch of thermal expansion coefficients during ceramic co-firing.

[0018] As an optional implementation, the feed electrode includes a plurality of spaced feed connection portions, and the first capacitor structure is connected to the corresponding feed connection portions through a plurality of conductor portions.

[0019] To overcome the potential problems of unstable contact impedance and insufficient mechanical strength associated with single-point feeding, the feeding electrode in this embodiment is not a single large-area pad, but rather divided into multiple spaced feeding connection parts. This effectively creates multiple supporting pillars between the first capacitor structure and the feeding electrode. This multi-point support method increases the bending resistance of the first capacitor structure and mitigates internal electrode delamination or breakage caused by thermal expansion coefficient mismatch or external forces, thereby enhancing the structural strength of the LTCC filter. Furthermore, the parallel arrangement of multiple conductors increases the current flow cross-sectional area and reduces the contact resistance at the feeding point, thus enhancing the electrical stability and consistency during dual-frequency signal input and reducing signal attenuation.

[0020] As an optional implementation, the first signal electrode and the second signal electrode are disposed on both sides of the feed electrode along the second direction, and a direction mark is provided on the top surface of the ceramic body, and the projection of the direction mark on the bottom surface is close to the first signal electrode or the second signal electrode. The second direction intersects with the first direction.

[0021] To prevent operators from confusing the first and second signal electrodes during mounting or troubleshooting, this application incorporates a directional marker on the top surface of the ceramic body. This marker is designed to be positioned close to either the first or second signal electrode. This top-surface directional marker allows the LTCC filter to be quickly and accurately identified and located during surface mount technology (SMT) processes, improving the reliability of the mounting process.

[0022] Secondly, this application also discloses a terminal device, the terminal device including a circuit board and an LTCC filter as described in the first aspect, wherein the bottom electrode of the LTCC filter is connected to the circuit board.

[0023] As an optional implementation, the circuit board includes a board body and a first microstrip line and a second microstrip line disposed on the board body, the feed electrode is connected to the board body, the first signal electrode is connected to the first microstrip line, and the second signal electrode is connected to the second microstrip line.

[0024] As an optional implementation, the operating frequency range of the first frequency band is 2.3GHz-2.5GHz, and the operating frequency range of the second frequency band is 4.6GHz-6.2GHz.

[0025] Compared with the prior art, this application provides an LTCC filter and a terminal device. The LTCC filter has a first capacitor structure disposed within its ceramic body as a common feed unit, and a second capacitor structure connected to a first signal electrode and a third capacitor structure connected to a second signal electrode are respectively configured. By aligning the projections of the second capacitor structure and the first capacitor structure in a first direction to form a first capacitive coupling, and by spacing the third capacitor structure from the first capacitor structure to form a second capacitive coupling, it can support a first frequency band and a second frequency band with different frequency ranges. Therefore, the LTCC filter of this application, by setting the capacitive coupling relationship among the first, second, and third capacitor structures, can support two different frequency ranges (first and second frequency bands). Furthermore, the stacking design of the second and first capacitor structures in the first direction reduces the overall size of the LTCC filter. Simultaneously, the spacing between the third and second capacitor structures avoids interference between them, effectively improving their isolation. As can be seen, the LTCC filter of this application can achieve a compact structure and save internal space of the terminal equipment, while also achieving stability and reliability of dual-frequency communication, thereby improving the communication performance of the terminal equipment. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the LTCC filter disclosed in the embodiments of this application; Figure 2 yes Figure 1 Top view of an LTCC filter; Figure 3 yes Figure 1 A front view of the LTCC filter in the image; Figure 4 yes Figure 3 A cross-sectional view of the LTCC filter in the AA direction; Figure 5 This is a schematic diagram of the structure of a partial LTCC filter disclosed in an embodiment of this application; Figure 6 This is a schematic diagram of the LTCC filter with directional markings disclosed in the embodiments of this application; Figure 7 This is a voltage standing wave ratio (VSWR) diagram of the LTCC filter disclosed in the embodiments of this application; Figure 8 This is a schematic diagram of the terminal device disclosed in the embodiments of this application; Figure 9 This is a schematic diagram of the antenna module in the terminal device disclosed in the embodiments of this application.

[0028] Explanation of reference numerals in the attached figures: LTCC filter-100; Terminal equipment-200; Ceramic body-10; Top surface-11; Bottom surface-12; First side-13; Second side-14; Bottom electrode-20; Feed electrode-21; First signal electrode-22; Second signal electrode-23; Feed connection part-24; Conductor part-25; First capacitor structure - 30; Second capacitor structure - 40; Second capacitor piece - 41; Third capacitor structure - 50; Third capacitor piece - 51; C1 capacitor piece - 31; C2 capacitor piece - 511; C3 capacitor piece - 512; C4 capacitor piece - 513; C5 capacitor piece - 411; C6 capacitor piece - 412; C7 capacitor piece - 413. Connecting conductor - 60; Through hole - 61; Direction indicator - 70; Circuit board - 80; First microstrip line - L1; Second microstrip line - L2; First direction - F1; Second direction - F2; Third direction - F3; Length - L; Width - W; Height - H. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] In this application, the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0031] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0032] Furthermore, the terms "installation," "setting," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0033] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0034] LTCC (Low-Temperature Co-fired Ceramic) refers to a process in which conductive pastes such as silver, copper, and gold are printed onto unsintered cast ceramic tapes as internal electrodes, which are then stacked in multiple layers and co-fired at temperatures below 900°C. Designers can select ceramic materials with different dielectric constants according to specific impedance matching requirements.

[0035] As described in the background section of this application, in order to achieve antenna miniaturization and integration, the LTCC dual-band solution faces two problems in balancing size and performance. If a multi-layer patch vertical stacking scheme is adopted, although dual-band can be achieved, the strong mutual coupling between the upper and lower radiators makes the tuning of the two frequency bands mutually restrictive, and increases the number and thickness of ceramic layers. If a single patch multi-mode excitation scheme is adopted, although the structure is simple, it is difficult to meet the radiation performance and isolation of the two frequency bands in a limited space when facing application scenarios with large frequency band spacing.

[0036] Based on this, this application discloses an LTCC filter and a terminal device, constructing an asymmetric LTCC filter structure that combines vertical overlapping coupling and lateral spacing coupling. For the longer wavelength first frequency band, coupling is constructed by overlapping the large-area projection of the second capacitor structure with the first capacitor structure to obtain sufficient capacitance. For the shorter wavelength second frequency band, edge coupling is constructed by using a spaced third capacitor structure with the first capacitor structure to match high-frequency characteristics and naturally block low-frequency signals. This design strategy cleverly separates the tuning structures of different frequency bands in physical space, thereby achieving independent tuning of dual-band signals, high isolation, and excellent radiation performance while maintaining a small size.

[0037] The LTCC filter and terminal device of this application will be described in detail below with reference to the accompanying drawings.

[0038] Please see Figures 1 to 4 , Figure 1 This is a schematic diagram of the structure of the LTCC filter 100 disclosed in an embodiment of this application. Figure 2 yes Figure 1 Top view of the LTCC filter 100 Figure 3 yes Figure 1 Front view of LTCC filter 100 in the image. Figure 4 yes Figure 3 A cross-sectional view of an LTCC filter 100 in the AA direction. This application discloses an LTCC filter 100, comprising a ceramic body 10.

[0039] The ceramic body 10 includes a top surface 11 and a bottom surface 12 along a first direction F1, two end surfaces along a second direction F2, and two side surfaces along a third direction F3. The two end surfaces connect the top and bottom surfaces, and the two side surfaces also connect to the top and bottom surfaces, respectively. Thus, the first direction F1, the second direction F2, and the third direction F3 are perpendicular to each other.

[0040] In other words, the ceramic body 10 is a cuboid. The first direction F1 can be the height direction of the ceramic body 10, the second direction F2 can be the length direction of the ceramic body 10, and the third direction F3 is the width direction (or thickness direction) of the ceramic body 10. Of course, in some other embodiments, the directions can be reversed. For example, the first direction F1 can be the length direction of the ceramic body 10, the second direction F2 can be the height direction of the ceramic body 10, and the third direction F3 can be the width direction of the ceramic body 10.

[0041] This application embodiment uses the first direction F1 as the height direction of the ceramic body 10, the second direction F2 as the length direction of the ceramic body 10, and the third direction F3 as the width direction of the ceramic body 10 as an example for illustration.

[0042] In some embodiments, the LTCC filter 100 includes a bottom electrode 20 disposed on the bottom surface 12. The bottom electrode 20 includes a feed electrode 21, a first signal electrode 22, and a second signal electrode 23 disposed at intervals. When the LTCC filter is applied to a terminal device, the bottom surface of the ceramic body 10 can be disposed on the circuit board of the terminal device, so that the bottom electrode can be electrically connected to the circuit board of the terminal device to realize the filtering function of the LTCC.

[0043] In some embodiments, the LTCC includes a first capacitor structure 30, a second capacitor structure 40, and a third capacitor structure 50. The first capacitor structure 30 is disposed within the ceramic body 10 and electrically connected to the feed electrode 21. The second capacitor structure 40 is disposed within the ceramic body 10 and electrically connected to the first signal electrode 22. The projections of the second capacitor structure 40 and the first capacitor structure 30 in a first direction F1 at least partially overlap to form a first capacitive coupling to support a first frequency band. The third capacitor structure 50 is disposed within the ceramic body 10 and connected to the second signal electrode 23. The third capacitor structure 50 and the first capacitor structure 30 are spaced apart to form a second capacitive coupling to support a second frequency band. The first and second frequency bands are different frequency bands.

[0044] Specifically, the ceramic body 10 serves as the substrate and is typically formed by laminating and sintering multiple dielectric layers. The bottom electrode 20 includes a feed electrode 21 for input signals and a first signal electrode 22 and a second signal electrode 23 corresponding to different frequency bands for output. In the internal structure, a first capacitor structure 30 serves as a common access terminal and is electrically connected to the bottom feed electrode 21. A second capacitor structure 40 is connected to the first signal electrode 22 and is used to transmit the first frequency band signal. A third capacitor structure 50 is connected to the second signal electrode 23 and is used to transmit the second frequency band signal.

[0045] With the above-described structure, the projection of the second capacitor structure 40 onto the projection of the first capacitor structure 30 in the first direction F1 (that is, the height direction of the ceramic body) is at least partially overlapping. This stacked, facing arrangement creates a large facing area between the two, thereby providing strong capacitive coupling capability, allowing lower-frequency first-band signals to pass smoothly. Simultaneously, the third capacitor structure 50 is spaced apart from the first capacitor structure 30 within the ceramic body 10, meaning there is little or no vertical projection overlap between them. This arrangement allows the third capacitor structure 50 and the first capacitor structure 30 to primarily rely on edge electric field effects to form second capacitive coupling. The strength of this coupling can match the transmission requirements of higher-frequency second-band signals, and this spatial distance effectively isolates interference from first-band signals.

[0046] As can be seen, the LTCC filter 100 of this application achieves independent tuning of dual-band signals within the same package through the aforementioned spatial layout. Specifically, the first band utilizes the overlapping of the first direction F1 to obtain a large capacitor to match the low frequency, while the second band utilizes the spaced arrangement to obtain capacitors and enhance isolation to match the high frequency. This design effectively reduces the area occupied by the device on the circuit board.

[0047] In some embodiments, the operating frequency range of the first frequency band is 2.3GHz-2.5GHz, and the operating frequency range of the second frequency band is 4.6GHz-6.2GHz.

[0048] Specifically, the operating frequency range typically refers to the frequency interval where the filter's return loss is less than a specific threshold (e.g., -10dB) or its voltage standing wave ratio (VSWR) is less than a specific value (e.g., 2.0 or 2.5). Within this range, the filter exhibits good impedance matching characteristics and can effectively transmit radio frequency energy. In this application, the operating frequency range of the first band is set to 2.3GHz to 2.5GHz, covering globally common industrial, scientific, and medical frequency bands. The operating frequency range of the second band is set to 4.6GHz to 6.2GHz, covering mainstream 5G frequency bands and some 6 / 6E extended frequency bands. By covering these two wide frequency bands, the LTCC filter 100 can meet various frequency requirements.

[0049] It is understandable that the operating frequency range of the first frequency band is 2.3GHz-2.5GHz, and its specific operating frequencies may include, but are not limited to: 2.30GHz, 2.32GHz, 2.34GHz, 2.36GHz, 2.38GHz, 2.40GHz, 2.41GHz, 2.43GHz, 2.45GHz, 2.47GHz, 2.49GHz, and 2.50GHz. It is understood that the operating frequency range of the second frequency band is 4.6GHz-6.2GHz, and its specific operating frequencies may include, but are not limited to: 4.60GHz, 4.70GHz, 4.80GHz, 4.90GHz, 5.00GHz, 5.10GHz, 5.20GHz, 5.30GHz, 5.40GHz, 5.50GHz, 5.60GHz, 5.70GHz, 5.80GHz, 5.90GHz, 6.00GHz, 6.10GHz, and 6.20GHz.

[0050] In some embodiments, such as Figure 1 and Figure 2 As shown, the second capacitor structure 40 and the third capacitor structure 50 are respectively disposed on both sides of the first capacitor structure 30 along the second direction F2, and along the first direction F1 and the second direction F2, the third capacitor structure 50 and the first capacitor structure 30 are disposed at intervals.

[0051] Specifically, the second capacitor structure 40 and the third capacitor structure 50 are respectively disposed on both sides of the first capacitor structure 30, which serves as a common power supply unit, along the second direction F2 (e.g., the length direction of the ceramic body 10). This structure, with power supply in the middle and distributed on both sides, effectively increases the spatial distance between the resonant circuits of the first and second frequency bands. By arranging the capacitor structures that process different frequencies at both ends of the first capacitor structure 30, the electromagnetic coupling and signal crosstalk between the two frequency bands are effectively reduced, thereby achieving isolation of the two frequency band signals within the same miniature package and improving the dual-frequency interference problem commonly found in compact designs.

[0052] Furthermore, since the third capacitor structure 50 does not overlap with the first capacitor structure 30 along the first direction F1, and they also maintain a certain distance along the second direction F2 (horizontal direction), this arrangement, maintaining spacing both vertically and horizontally, is for precise control of the coupling amount in the second frequency band (high-frequency band). Because a stacked design for high-frequency signals can easily lead to excessively large coupling capacitance that cannot match the requirements of the 5G frequency band, the third capacitor structure 50 utilizes the edge electric field for weak coupling, thereby achieving signal feed and impedance matching for the second frequency band.

[0053] Preferably, the minimum spacing between the first capacitor structure 30 and the third capacitor structure 50 in the second direction F2 can be designed to be 147μm-167μm. This spacing value is a critical value optimized based on the dielectric constant of LTCC material and the wavelength characteristics of the 5GHz band. If the spacing is too small, for example, less than 147μm, the edge coupling effect will be enhanced, resulting in an excessively wide and difficult-to-control 5G band bandwidth. If the spacing is too large, it will easily lead to excessive signal transmission loss.

[0054] It is understandable that the minimum spacing between the first capacitor structure 30 and the third capacitor structure 50 in the second direction F2 can be designed to be between 147μm and 167μm. Specifically, the minimum spacing can include, but is not limited to: 147μm, 149μm, 151μm, 153μm, 155μm, 157μm, 159μm, 161μm, 163μm, and 167μm.

[0055] It is understood that the symmetrical distribution of the capacitors on both sides of the first capacitor structure 30 is not required. In other words, the second capacitor structure 40 and the third capacitor structure 50 do not necessarily need to be symmetrically arranged based on the first capacitor structure 30. Designers can adjust the space ratio on both sides according to the specific length-to-width ratio of the ceramic body 10. For example, since the wavelength of the 2.4G band is longer, the required capacitor volume may be larger, so the space ratio on the side where it is located may be larger than that on the side where the 5G band is located. This embodiment does not impose specific limitations on this.

[0056] In some embodiments, such as Figures 1 to 3 As shown, the first capacitor structure 30 has a first side 13 and a second side 14 opposite each other along the second direction F2. A portion of the second capacitor structure 40 is located on the first side 13, and at least a portion of the second capacitor structure 40 extends along the second direction F2 to the second side 14 or beyond the second side 14 so as to coincide with the projection of the first capacitor structure 30 in the first direction F1. The third capacitor structure 50 is disposed on the second side 14. In both the first direction F1 and the second direction F2, the third capacitor structure 50 is spaced apart from the second capacitor structure 40.

[0057] Specifically, the first capacitor structure 30 has a first side 13 and a second side 14 opposite each other along the second direction F2. The second capacitor structure 40 is not limited to a single region; part of it is located on the first side 13, while another part extends along the second direction F2, crossing the central region of the first capacitor structure 30 until it reaches or exceeds the second side 14. Thus, the second capacitor structure 40 and the first capacitor structure 30 have a large area of ​​overlapping projection in the first direction, thereby forming a larger coupling capacitance, allowing the second capacitor structure 40 to support a lower frequency in the first frequency band. Meanwhile, the third capacitor structure 50 is disposed on the second side, spaced apart from both the first capacitor structure 30 and the second capacitor structure 40. In this way, the third capacitor structure 50 and the first capacitor structure 30 achieve weak coupling through this edge electric field, allowing the third capacitor structure 50 to support a lower frequency in the second frequency band. In other words, this arrangement, while supporting different frequency bands, also reduces electromagnetic coupling and signal crosstalk between the two frequency bands by arranging capacitor structures for processing different frequencies at opposite ends of the first capacitor structure 30, thus helping to improve the problem of dual-frequency interference.

[0058] In some embodiments, at least a portion of the second capacitor structure 40 extends beyond the second side 14 along the second direction F2 to coincide with the projection of the first capacitor structure 30 in the first direction F1. Specifically, the protrusion length of the second capacitor structure 40 relative to the first capacitor structure 30 in the second direction F2 can be controlled between 48μm and 53μm, for example, 48μm, 49μm, 50μm, 51μm, 52μm, and 53μm. This extension design serves to precisely adjust the coupling capacitance value so that the trough of the return loss curve of the first frequency band, i.e., the deepest point of return loss, falls at a frequency near 2440MHz, thereby ensuring that the device has good transmission efficiency in the standard Wi-Fi frequency band.

[0059] Understandably, in order to achieve the aforementioned extension while maintaining avoidance of the third capacitor structure 50, the planar shape of the second capacitor structure 40 can be designed as an irregular shape, such as a "T" or "L" shape. That is, the second capacitor structure 40 may include a main capacitor portion connected to the first signal electrode and an extension arm connected at an angle to the main capacitor portion. The extension arm may extend to the second side of the first capacitor structure 30 so as to at least partially coincide with the projection of the first capacitor structure 30 in the first direction. Thus, by changing the width or protruding shape of the extension arm, the bandwidth performance can be further fine-tuned.

[0060] In some embodiments, at least one of the first capacitor structure 30, the second capacitor structure 40, and the third capacitor structure 50 may include a multilayer structure, which will be described separately below.

[0061] In some examples, such as Figure 3 As shown, the third capacitor structure 50 includes multiple layers of third capacitor sheets 51 that are spaced apart and electrically connected to each other along the first direction F1, wherein one layer of the third capacitor sheet 51 is located on the same layer as the first capacitor structure 30 in the first direction F1.

[0062] Specifically, in order to meet the capacitance value required for high-frequency resonance within a relatively small ceramic body 10, while maintaining a distance from the first capacitor structure 30, the third capacitor structure 50 adopts a stacked design in which multiple layers of capacitor sheets are spaced apart along the first direction F1 and connected in parallel. This multi-layer stacked design can increase the capacitance density by increasing the surface area of ​​the electrodes, and by controlling that a specific layer of capacitor sheet is on the same plane as the first capacitor structure 30, the coupling boundary between the two can be better defined.

[0063] For example, suppose the first capacitor structure 30 is mainly composed of a C1 capacitor sheet 31 disposed in a certain layer inside the ceramic body 10. Suppose the third capacitor structure 50 has three layers of capacitor sheet 51, namely a C2 capacitor sheet 511, a C3 capacitor sheet 512, and a C4 capacitor sheet 513 arranged from top to bottom along the first direction F1, and these three layers of capacitor sheets are electrically connected to each other. In this configuration, the bottommost C4 capacitor sheet 513 is designed to be located on the same dielectric layer of the ceramic body 10 as the C1 capacitor sheet 31. This means that during the manufacturing process, the C4 capacitor sheet 513 and the C1 capacitor sheet 31 are printed in the same layer through the same screen printing process. Therefore, the horizontal spacing between the C4 capacitor sheet 513 and the C1 capacitor sheet 31 depends on the accuracy of the printing screen and is not affected by the alignment error of the multilayer ceramic lamination. This same-layer design not only ensures the consistency and stability of the second frequency band signal coupling path, but also makes the edge coupling strength of the high-frequency part highly controllable, thereby ensuring the consistency of products during mass production.

[0064] Understandably, in practical applications, designers can increase or decrease the number of capacitor layers in the third capacitor structure 50 depending on the target frequency band. For example, to support lower frequencies (such as 4GHz), the number of layers can be increased to increase the capacitance, such as 4 or 5 layers. To support higher frequencies (such as 6GHz), the number of layers can be reduced, such as 2 or 1 layer.

[0065] In some embodiments, such as Figure 4 , Figure 5 As shown, Figure 5 This is a schematic diagram of the structure of the LTCC filter 100 (partial) disclosed in the embodiments of this application. The second capacitor structure 40 includes multiple layers of second capacitor sheets 41 that are spaced apart and electrically connected to each other along the first direction F1. One layer of second capacitor sheet 41 is located on the same layer as the first capacitor structure 30 in the first direction F1, and the other layer of second capacitor sheet 41 is located at least partially on one side of the first capacitor structure 30 along the first direction F1 so as to at least partially overlap with the projection of the first capacitor structure 30 in the first direction F1.

[0066] Specifically, the second capacitor structure 40 adopts a structural design that combines vertical overlapping coupling and edge coupling. The second capacitor structure 40 consists of multiple layers of second capacitor sheets distributed at intervals along the first direction F1. These second capacitor sheets are electrically connected to each other and together form a large-area induction electrode.

[0067] As illustrated in the previous embodiments regarding the first capacitor structure 30 and the third capacitor structure 50, assume that the second capacitor structure 40 includes C5 capacitor sheet 411, C6 capacitor sheet 412, and C7 capacitor sheet 413 arranged sequentially from top to bottom along the first direction F1. In this case, C7 capacitor sheet 413 is designed to be located on the same layer of the ceramic body 10 as C1 capacitor sheet 31 in the first capacitor structure 30. On this layer, C7 capacitor sheet 413 and C1 capacitor sheet 31 also maintain a certain distance along the second direction F2, without vertical overlap, but forming edge electric field coupling. Furthermore, like C7 capacitor sheet 413, C5 capacitor sheet 411 and C1 capacitor sheet 31 do not vertically overlap along the first direction F1, also forming edge electric field coupling. That is, C7 capacitor sheet 413 and C5 capacitor sheet 411, as auxiliary capacitor sheets of the second capacitor structure 40, form edge electric field coupling with C1 capacitor sheet 31 of the first capacitor structure 30.

[0068] Meanwhile, capacitor C6 412 is configured to at least partially cover the area where capacitor C1 31 is located on the projection along the first direction F1. This directly overlapping design provides the capacitance value required for the first frequency circuit resonance. Through this structural design combining vertical overlapping coupling and edge coupling, the second capacitor structure 40 can effectively induce energy from the first capacitor structure 30, thereby enabling the LTCC filter 100 to have a better return loss valley.

[0069] It is understandable that in practical applications, designers can increase or decrease the number of capacitor layers in the second capacitor structure 40 according to the target frequency band, such as 1 layer, 2 layers, 3 layers, 4 layers, 5 layers, etc. This embodiment does not limit this.

[0070] In some embodiments, such as Figure 5 As shown, the second capacitor structure 40 and / or the third capacitor structure 50 further include multiple connecting conductors 60. The second capacitor sheet 41 and / or the third capacitor sheet 51 are provided with through holes 61. The connecting conductors 60 pass through the through holes 61 along the first direction F1 to connect two adjacent second capacitor sheets 41 or two adjacent third capacitor sheets 51. The second capacitor sheet 41 and / or the third capacitor sheet 51 are also electrically connected to corresponding signal electrodes via the connecting conductors 60.

[0071] Specifically, the connecting conductor 60 penetrates the ceramic dielectric layer to electrically connect the multilayer capacitor sheets in parallel, creating a low-impedance transmission channel. This vertical interconnection not only ensures the consistency of the potential of each layer, but also acts as a mechanical reinforcing rib, improving the delamination or warping phenomenon caused by the mismatch of thermal expansion coefficients during the ceramic co-firing process.

[0072] Furthermore, depending on the performance requirements of different frequency bands in actual applications, this vertical interconnect structure can be flexibly applied to the second capacitor structure 40, the third capacitor structure 50, or both simultaneously.

[0073] In one example, only the capacitor sheets of the second capacitor structure 40 (corresponding to the first frequency band) have pre-set corresponding through holes 61. Multiple connecting conductors 60 pass through these through holes 61 along the first direction F1 and eventually extend to the first signal electrode 22 at the bottom.

[0074] In another example, only the capacitor layers of the third capacitor structure 50 (corresponding to the second frequency band) have pre-set vias 61 with corresponding positions. Multiple connecting conductors 60 pass through these vias 61 along the first direction F1 and eventually extend to the second signal electrode 23 at the bottom.

[0075] In another example, the second capacitor structure 40 and the third capacitor structure 50 each have their respective multilayer capacitor sheets connected in series via connecting conductors 60, and are respectively fixed to the first signal electrode 22 and the second signal electrode 23 at the bottom. This design not only takes into account structural stability and low-loss transmission requirements, but also enhances the bonding strength of the entire ceramic block. The connecting conductors 60, which pass through the second capacitor sheet 41 and the third capacitor sheet 51 respectively, enable the LTCC filter 100 to form a solid physical connection, giving the product stronger resistance to damage in subsequent surface mount and drop tests.

[0076] It is understandable that when only the second capacitor structure 40 or only the third capacitor structure 50 uses the via 61 to connect their respective capacitor sheets to each other with the connecting conductor 60, the other capacitor structure can use metallization strips printed on the sidewall of the ceramic body 10 to achieve electrical connection between adjacent capacitor sheets. This sidewall metallization method helps to reduce the number of vias inside the device, thereby improving the utilization rate of the planar wiring area.

[0077] It is understood that the connecting conductor 60 is typically formed by filling conductive paste (such as silver paste or copper paste) after drilling holes in the green ceramic tape. The size and number of vias 61 can be adjusted according to current density and impedance requirements. For example, multiple vias 61 arranged in an array can be provided on the same layer of capacitor sheet, but this embodiment does not limit this.

[0078] It is understandable that the first signal electrode 22 and the second signal electrode 23 at the bottom serve as connection ports for external circuits, and their area is usually larger than the cross-sectional area of ​​the via 61.

[0079] It is understood that the connecting conductor 60 passes through the ceramic dielectric layer along the first direction F1, and its shape can be cylindrical, square, etc., which is not limited in this embodiment.

[0080] It is understood that the material used for the connecting conductor 60 is usually a metal with high conductivity, such as silver, copper or silver-palladium alloy. The specific selection needs to be matched with the sintering temperature of the ceramic body 10 and the material of the internal electrode. This embodiment does not make specific limitations on this.

[0081] In some embodiments, such as Figure 5 As shown, the feed electrode 21 includes a plurality of feed connection portions 24 spaced apart, and the first capacitor structure 30 is connected to the corresponding feed connection portions 24 through a plurality of conductor portions 25.

[0082] Specifically, in order to overcome the problems of unstable contact impedance and insufficient mechanical strength that may exist in single-point power feeding, the power feeding electrode 21 in this embodiment is not a single large-area pad, but is divided into multiple spaced power feeding connection parts 24.

[0083] For example, the feed electrode 21 may include four independent pads, and correspondingly, the first capacitor structure 30 located inside the ceramic body 10 is fixed to the four independent pads by passing through the dielectric layer through multiple conductor portions 25, such as four vertical through holes.

[0084] The feed electrode adopts this design, which, on the one hand, is equivalent to constructing multiple supporting pillars between the first capacitor structure 30 and the feed electrode 21. This multi-point support structure enhances the bending resistance of the first capacitor structure 30 and improves the internal electrode delamination or breakage caused by thermal expansion coefficient mismatch or external force, thereby enhancing the structural strength of the LTCC filter 100. On the other hand, the parallel arrangement of multiple conductor portions 25 increases the current flow cross-sectional area and reduces the contact resistance at the feed point, thereby enhancing the electrical stability and consistency during dual-frequency signal input and reducing signal attenuation.

[0085] It is understandable that the conductor portion 25 can reuse the aforementioned connecting conductor 60 in terms of structure and process. That is, the conductor portion 25 connecting the first capacitor structure 30 and the power supply connection portion 24, and the connecting conductor 60 connecting the multilayer capacitor sheet of the first capacitor structure 30 or the second capacitor structure 40, can adopt the same structure and be formed in the same sintering process using the same conductive paste.

[0086] It is understood that the number of power supply connection parts 24 is not limited to 4. Designers can design 2, 3, 4, 5, 6 or more depending on the area of ​​the first capacitor structure 30. This embodiment does not limit this.

[0087] In some embodiments, such as Figure 6 As shown, Figure 6This is a schematic diagram of an LTCC filter 100 with a direction indicator 70 disclosed in an embodiment of this application. The first signal electrode 22 and the second signal electrode 23 are disposed on both sides of the feed electrode 21 along the second direction F2. The direction indicator 70 is disposed on the top surface 11 of the ceramic body 10. The projection of the direction indicator 70 on the bottom surface 12 is close to the first signal electrode 22 or the second signal electrode 23.

[0088] Specifically, to prevent operators from confusing the two signal ports, the first signal electrode 22 and the second signal electrode 23, during mounting or troubleshooting, this LTCC filter 100 has a direction indicator 70 on the top surface 11 of the ceramic body 10. This direction indicator 70 is designed to be close to either the first signal electrode 22 or the second signal electrode 23. This top surface direction indicator 70 allows the LTCC filter 100 to be quickly and accurately identified and positioned during surface mount technology processes, thus improving the reliability of the mounting process.

[0089] It is understood that the direction marking 70 can be a geometric pattern or text (such as dots, short lines or letters) with a clear indication function, or it can be ink dots printed on the top surface of the LTCC filter 100, laser-etched marking lines, etc. This embodiment does not limit this.

[0090] In some embodiments, such as Figure 6 As shown, the LTCC filter 100 has the following dimensions: length L 1.6mm ± 0.1mm, width W 0.8mm ± 0.1mm, and height H 0.38mm ± 0.1mm. Through the design combining vertical stacking and lateral spacing described in the foregoing embodiments, the LTCC filter 100 of this application successfully compresses a complex resonant structure supporting both 2.4GHz and 5GHz dual-band operation into a tiny volume. This miniaturized design effectively saves design space, enabling manufacturers to integrate more functional modules or larger capacity batteries within a limited space.

[0091] It is understood that the tolerance range of 0.1 mm is based on the characteristics of LTCC material. In this embodiment, the preferred size range of the LTCC filter 100 is length L 1.6 mm, width W 0.8 mm, and height H 0.38 mm.

[0092] The VSWR (Voltage Standing Wave Ratio) characteristics of the LTCC filter 100 using this application and its impedance matching performance in different frequency bands will be described in detail below.

[0093] Please refer to Figure 7 , Figure 7 This is a voltage standing wave ratio (VSWR) diagram of the LTCC filter 100 disclosed in an embodiment of this application. Figure 7 The horizontal axis in the table represents frequency in GHz, and the vertical axis represents VSWR, which is the voltage standing wave ratio. Under simulated operating conditions, the VSWR values ​​of the embodiments of this application at key frequency points in the first and second frequency bands are analyzed. The specific data are shown in Table 1 below: Table 1

[0094] Based on the simulation results, Table 1 and Figure 7 It can be seen that the LTCC filter 100 of this application exhibits excellent resonant characteristics and impedance matching capability in dual-band operating mode.

[0095] Specifically, when the operating frequency is 2.42 GHz, the VSWR value of this embodiment is reduced to 1.16. In radio frequency engineering, VSWR=1.0 represents an ideal fully matched state with no energy reflection. The value of 1.16 in this application is close to the ideal value, which means that at the main operating frequency of 2.4 GHz, most of the radio frequency energy can be effectively transmitted or radiated through the resonant circuit formed by the second capacitor structure 40 and the microstrip line of the circuit board 80, with extremely low reflection loss. This shows that this application achieves efficient impedance matching in a small size through the internal vertically stacked capacitor coupling structure.

[0096] When the operating frequency is 5.50 GHz, the VSWR value of this embodiment is 1.21. This data indicates that at the center frequency of the second frequency band, the lateral spacing coupling mechanism between the third capacitor structure 50 and the first capacitor structure 30 not only achieves high-frequency signal coupling but also maintains a low voltage standing wave ratio. This demonstrates that even in high-frequency paths relying on weak coupling via edge electric fields, this application can still maintain an efficient energy transmission channel, avoiding high reflection problems caused by insufficient coupling.

[0097] Regarding bandwidth coverage, observing the waveform curve in the 2.4GHz band, the VSWR curve exhibits a steep, deep valley shape within the range of 2.35GHz to 2.54GHz. This deep valley shape indicates that the filter has a high quality factor within the target frequency band and can effectively filter out out-of-band interference signals. In the 5GHz band, observing the range of 4.68GHz to 6.17GHz, the VSWR curve exhibits a wider valley shape. This broadband characteristic allows the LTCC filter 100 of this application to effectively cover 5G Wi-Fi (5.15-5.85GHz) and even part of the Wi-Fi 6E band, demonstrating its good frequency adaptability in the high-frequency band.

[0098] Furthermore, between the two passbands, for example, between 3.0 GHz and 4.0 GHz, the VSWR value increases to over 5.0. This high-impedance region effectively isolates the first and second frequency bands, preventing crosstalk between the two bands.

[0099] As can be seen, the LTCC filter 100 of this application has excellent independent tuning capability in dual-band coexistence scenarios. Through the internal differentiated capacitor structure design (vertical coupling for low frequency, lateral coupling for high frequency), this application achieves a wide effective operating bandwidth while ensuring low VSWR (<1.3) in both frequency bands, which can effectively improve the wireless communication quality of the terminal device 200 and reduce the risk of signal stuttering or dropped calls caused by antenna mismatch.

[0100] Secondly, such as Figure 8 As shown, Figure 8 This is a schematic diagram of a terminal device 200 disclosed in an embodiment of this application. This application also discloses a terminal device 200, which includes an LTCC filter 100 of the first aspect.

[0101] Specifically, such as Figure 9 As shown, Figure 9 This is a schematic diagram of the antenna module in the terminal device 200 disclosed in this application embodiment. The terminal device 200 includes an LTCC filter 100, which is mounted on the circuit board 80 of the terminal device 200. The LTCC filter 100 and the circuit board 80 form a complete radio frequency component. The surface of the circuit board 80 is printed with metal traces, namely the first microstrip line L1 and the second microstrip line L2, which not only serve as transmission lines but also as radiators of the antenna. The LTCC filter 100 is fixed to the circuit board 80 using a surface mount process through the bottom pads (i.e., the feed electrode 21, the first signal electrode 22, and the second signal electrode 23).

[0102] In terms of electrical connection, one end of the first microstrip line L1 is physically connected to the first signal electrode 22 of the LTCC filter 100, and one end of the second microstrip line L2 is connected to the second signal electrode 23. Its working principle is based on the LC series resonance mechanism. The second capacitor structure 40 inside the LTCC filter 100 provides a precise capacitance value, while the first microstrip line L1 on the external circuit board 80 provides inductive reactance. When the input signal frequency is in the first frequency band (e.g., 2.4 GHz), the capacitive reactance of the second capacitor structure 40 cancels out the inductive reactance of the first microstrip line L1, forming a low-impedance series resonant circuit. This allows high-frequency current to flow efficiently into the first microstrip line L1 and excite an alternating electromagnetic field in the surrounding space, thereby converting electrical energy into electromagnetic waves that are radiated outwards.

[0103] Similarly, the internal third capacitor structure 50 works in conjunction with the external second microstrip line L2 to form another independent resonant radiation loop in the second frequency band (e.g., 5GHz). This scheme successfully reduces the size of the LTCC filter 100 by integrating the capacitor tuning unit into the tiny LTCC filter 100 and keeping the inductor radiation unit on the circuit board 80. At the same time, it utilizes the length and shape flexibility of the traces on the circuit board 80 to optimize the radiation pattern and gain, solving the problem of the difficulty of deploying traditional large-size antennas in compact mobile terminals.

[0104] This separate design of the LTCC filter 100 and the microstrip line radiation on the circuit board 80 offers significant engineering advantages. This structure provides the antenna module with high design flexibility. Since the resonant frequency is determined by both internal capacitance and external inductance, and with fixed parameters, designers only need to change the length of the microstrip lines on the circuit board 80—specifically, the lengths of the first microstrip line L1 and the second microstrip line L2—to adjust the antenna frequency within a certain range. This means that the same standardized LTCC chip can be adapted to terminal devices 200 of different sizes and housing materials, requiring only minor adjustments to the routing during the circuit board 80 layout stage. There is no need to create custom ceramic chips for each project, which helps reduce R&D costs.

[0105] In summary, the terminal device 200 employs LTCC technology, achieving high integration and miniaturization of the LTCC filter 100 and antenna system. Stable splitting and tuning of dual-band signals are achieved within a small footprint, effectively avoiding mutual interference between the two bands and ensuring high isolation. Furthermore, the bottom electrode 20 of the filter is designed with multiple spaced feed connection sections 24, connected to the internal circuitry via multiple conductor sections 25, enhancing the reliability and stability of the ceramic body 10 under external impact.

[0106] By combining the microstrip lines on the external circuit board 80 and adjusting the physical length of the microstrip lines, the resonant frequency of the antenna can be flexibly and precisely controlled. This allows the same LTCC filter 100 to quickly adapt to the antenna matching requirements of different terminal devices 200, greatly shortening the product development cycle and improving the overall performance and market competitiveness of the terminal device 200.

[0107] It is understood that the terminal device 200 referred to in this application includes any electronic product that requires dual-band (such as Wi-Fi, 2.4GHz / 5GHz) wireless communication functionality. For example, the terminal device 200 may include: smartphones, tablets, laptops, smartwatches, smart bracelets, true wireless Bluetooth headsets, drones, portable medical monitoring devices, or vehicle communication modules, etc., and this embodiment does not specifically limit it.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An LTCC filter, characterized by, The application relates to a ceramic body, comprising a top surface and a bottom surface along a first direction; a bottom electrode arranged on the bottom surface, the bottom electrode comprising a feed electrode, a first signal electrode and a second signal electrode arranged at intervals; a first capacitor structure arranged in the ceramic body, the first capacitor structure being electrically connected to the feed electrode; a second capacitor structure arranged in the ceramic body, the second capacitor structure being electrically connected to the first signal electrode, the second capacitor structure and the first capacitor structure at least partially overlapping in projection along the first direction to form a first capacitive coupling to support a first frequency band; and a third capacitor structure arranged in the ceramic body, the third capacitor structure being connected to the second signal electrode, the third capacitor structure being arranged at intervals with the first capacitor structure to form a second capacitive coupling to support a second frequency band; wherein the first frequency band and the second frequency band are different frequency bands. The second capacitor structure and the third capacitor structure are arranged on both sides of the first capacitor structure along a second direction, and the third capacitor structure is arranged at intervals with the first capacitor structure along the first direction and the second direction. The second direction intersects the first direction. The first capacitor structure has a first side and a second side opposite along the second direction, part of the second capacitor structure is located on the first side, and at least part of the second capacitor structure extends to the second side or beyond the second side along the second direction to overlap with the projection of the first capacitor structure along the first direction, and the third capacitor structure is arranged on the second side, and the third capacitor structure is arranged at intervals with the second capacitor structure along the first direction and the second direction. The third capacitor structure comprises a plurality of third capacitor layers arranged at intervals along the first direction and electrically connected to each other, and one of the third capacitor layers is located at the same layer as the first capacitor structure along the first direction. The second capacitor structure comprises a plurality of second capacitor layers arranged at intervals along the first direction and electrically connected to each other, and one of the second capacitor layers is located at the same layer as the first capacitor structure along the first direction, and another of the second capacitor layers is at least partially located on one side of the first capacitor structure along the first direction to at least partially overlap with the projection of the first capacitor structure along the first direction. The second capacitor structure and / or the third capacitor structure further comprises a plurality of connection conductors, the second capacitor layer and / or the third capacitor layer is provided with a through hole, and the connection conductor is arranged in the through hole along the first direction to connect two adjacent second capacitor layers or two adjacent third capacitor layers.

2. The LTCC filter according to claim 1, characterized in that The second capacitor layer and / or the third capacitor layer is electrically connected to the corresponding signal electrode through the connection conductor. The feed electrode comprises a plurality of feed connection portions arranged at intervals, and the first capacitor structure is connected to the corresponding feed connection portion through a plurality of conductors.

3. The LTCC filter of claim 2, wherein ​ 4. The LTCC filter of claim 1, wherein, ​ 5. The LTCC filter of claim 4, characterized in that ​ 6. The LTCC filter of claim 5, wherein ​ ​ 7. The LTCC filter according to any one of claims 1 to 6, characterized in that ​ 8. The LTCC filter of claim 1, wherein, The first signal electrode and the second signal electrode are arranged on two sides of the feed electrode along a second direction, and a direction mark is arranged on a top surface of the ceramic body, a projection of the direction mark on the bottom surface is close to the first signal electrode or the second signal electrode. The second direction intersects the first direction.

9. A terminal device, comprising: The terminal device comprises a circuit board and the LTCC filter according to any one of claims 1-8, and the bottom electrode of the LTCC filter is connected to the circuit board.

10. The terminal device according to claim 9, characterized by The circuit board comprises a board body and a first microstrip line and a second microstrip line arranged on the board body, the feed electrode is connected to the board body, the first signal electrode is connected to the first microstrip line, and the second signal electrode is connected to the second microstrip line.

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