A micro filter and electronic device

Abstract

This application discloses a miniature filter and electronic device, relating to the field of radio frequency technology. The miniature filter includes a stacked first part and a second part, employing a 1 / 4λ resonator. The 1 / 4λ resonator includes a short-circuit portion located in the first part and an open-circuit portion located in the second part. The open-circuit portion of the 1 / 4λ resonator adopts a coplanar waveguide structure and uses a dielectric material with a dielectric constant of not less than 40 and a loss tangent of not more than 0.005. Thus, the electric field of the 1 / 4λ resonator is mainly concentrated in the high dielectric constant and low loss tangent dielectric material between its open-circuit end and the grounding metal layer on the same layer, with very little external radiation and minimal external influence, resulting in excellent electromagnetic shielding. It also helps to reduce the planar size of the resonator and improve the Q value of the resonator. Furthermore, the upper and lower parts of the miniature filter adopt a multi-layer vertical structure, which can be fabricated using CMOS technology and packaged at the chip level to meet high-frequency applications.

Description

Technical Field

[0001] This application relates to the field of radio frequency technology, and in particular to a miniature filter and electronic device. Background Technology

[0002] With the rapid development of modern communication technology, the popularization of 5G communication technology and the rapid development of the Internet of Things market, the spectrum is expanding to higher frequencies. This places higher demands on the key components of the radio frequency front end, such as filters. While ensuring high performance (low insertion loss, high suppression), size requirements are becoming increasingly stringent, and the trend of filter chipization is becoming more and more obvious.

[0003] Currently, common small filters are mostly microwave ceramic filters, such as dielectric filters and low-temperature co-fired ceramic (LTCC) filters, as well as surface acoustic wave (SAW) filters and thin-film bulk acoustic wave (FBAR) filters that utilize acoustic principles. While traditional microwave ceramic filters can achieve very high dielectric constants, those meeting high Q-value and low-loss requirements are mainly concentrated below a dielectric constant of 20, limiting size reduction. Furthermore, the higher the dielectric constant of the ceramic, the more severe the deterioration in the loss coefficient, failing to meet the high Q-value requirement, exhibiting a contradiction where the loss coefficient and dielectric constant are inversely proportional. Moreover, their manufacturing precision is limited to millimeters, making them unsuitable for high-frequency applications. SAW and FBAR filters also suffer from drawbacks such as a small usable frequency range and limited bandwidth.

[0004] Currently, common planar filters (such as microstrip filters, stripline filters, and substrate integrated waveguide (SIW) filters) are widely used in high-frequency applications and are easy to integrate, but they have disadvantages such as low Q value and large size. Due to the use of PCB technology, the processing accuracy is limited to the millimeter level, which is acceptable in the low-frequency range, but cannot meet the requirements in the high-frequency range.

[0005] Therefore, there is an urgent need to provide a filter that is small in size, has a high Q value, low loss, and can meet the requirements of high-frequency applications. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a filter that is small in size, has a high Q value, low loss, and can meet the requirements of high-frequency applications, as well as an electronic device including the filter.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] A first aspect of this application provides a microfilter, the microfilter comprising a first portion and a second portion stacked together;

[0009] The first part includes a first metal layer and a first dielectric layer and a second metal layer that are alternately stacked on the side of the first metal layer near the second part. The first metal layer is grounded. The layer of the first part closest to the second part is the second metal layer. The second metal layer includes a first annular portion. The first metal layer and the first annular portion of the adjacent second metal layer and the first annular portions of two adjacent second metal layers are electrically connected through a first metal via that penetrates the first dielectric layer and is arranged in an annular pattern.

[0010] The second part includes a third metal layer, a second dielectric layer, a fourth metal layer, and a third dielectric layer stacked in a direction opposite to the first part. The third metal layer includes a first pad portion and a second annular portion surrounding the first pad portion. The fourth metal layer includes a ground portion and an open-circuit portion. The ground portion has an opening, and the open-circuit portion is located within the opening. The ground portion is electrically connected to the second annular portion through a second metal via penetrating the second dielectric layer. The open-circuit portion is electrically connected to the first pad portion through a third metal via penetrating the second dielectric layer. The dielectric constant of the second dielectric layer and the third dielectric layer is not less than 40, and the loss tangent is not greater than 0.005.

[0011] The microfilter includes at least one 1 / 4λ resonator, which includes an open-circuit portion and a short-circuit portion. The open-circuit portion includes the open section, the third metal via, and the first pad section. The short-circuit portion is located in the first section and is located in each of the first dielectric layers and is surrounded by each of the first annular portions.

[0012] The first annular portion of the first part closest to the second part of the second metal layer and the second annular portion are electrically connected by a welding part, as are the short-circuit portion and the open-circuit portion.

[0013] Optionally, the materials of the second dielectric layer and the third dielectric layer are lithium niobate or lithium tantalate.

[0014] Optionally, the short-circuit portion includes a second pad portion located in each of the second metal layers, and adjacent second pad portions are electrically connected through a fourth metal via penetrating the first dielectric layer.

[0015] Optionally, the microfilter includes at least two of the 1 / 4λ resonators.

[0016] Optionally, the first part further includes a magnetic coupling connection line that connects the second pad portion of one layer of the two 1 / 4λ resonators.

[0017] Optionally, the first part further includes a shielding wall located between the two 1 / 4λ resonators, the shielding wall including shielding portions located in each of the second metal layers, and a plurality of fifth metal through holes penetrating the first dielectric layer to connect the shielding portions of adjacent two layers.

[0018] Optionally, the openings where the open sections of the two 1 / 4λ resonators are located are connected.

[0019] Optionally, a flying rod is provided in the two connected openings. The flying rod includes two coupling parts and a connecting part. One coupling part surrounds the open circuit part of one of the 1 / 4λ resonators, and the other coupling part surrounds the open circuit part of another 1 / 4λ resonator. The connecting part connects the two coupling parts.

[0020] Optionally, within the two connected openings, the open portions of the two 1 / 4λ resonators form an interdigitated structure.

[0021] A second aspect of this application provides an electronic device comprising any of the aforementioned miniature filters.

[0022] Compared with existing technologies, the above technical solution has the following advantages:

[0023] The microfilter provided in this application embodiment includes a first part and a second part stacked together. The first part includes a first metal layer and a first dielectric layer and a second metal layer stacked alternately on the side of the first metal layer near the second part. The first metal layer is grounded. The layer of the first part closest to the second part is the second metal layer. The second metal layer includes a first annular portion. The first metal layer and the first annular portion of the adjacent second metal layer, as well as the first annular portions of two adjacent second metal layers, are electrically connected through first metal vias that penetrate the first dielectric layer and are arranged in a ring. Thus, the first annular portion of each second metal layer in the first part and the first metal vias arranged in a ring around it approximately constitute a metal conductor, which together with the grounded first metal layer constitutes an electromagnetic shielding structure.

[0024] The second part includes a third metal layer, a second dielectric layer, a fourth metal layer, and a third dielectric layer stacked in a direction away from the first part. The third metal layer includes a first pad portion and a second annular portion surrounding the first pad portion. The fourth metal layer includes a ground portion and an open-circuit portion located within an opening of the ground portion. The ground portion is electrically connected to the second annular portion through a second metal via penetrating the second dielectric layer, and the open-circuit portion is electrically connected to the first pad portion through a third metal via penetrating the second dielectric layer. Furthermore, the microfilter includes at least one 1 / 4λ resonator. The 1 / 4λ resonator includes an open-circuit portion and a short-circuit portion. The open-circuit portion includes an open-circuit portion, a third metal via, and a first pad portion located in the second part. The short-circuit portion is located in the first part, specifically within each first dielectric layer, and surrounded by each first annular portion. The first annular portion and the second annular portion of the second metal layer closest to the second part in the first part are electrically connected via solder portions. Thus, the 1 / 4λ resonator... The open-circuit section (signal layer) and the grounded metal layer (i.e., grounding section) are coplanar, forming a coplanar waveguide structure. This allows the electric field of the 1 / 4λ resonator to be mainly concentrated between the open-circuit section and the grounding section. The upper and lower sides of the fourth metal layer containing the open-circuit section and the grounding section are the second dielectric layer and the third dielectric layer, respectively. The dielectric constant of the second dielectric layer and the third dielectric layer is not less than 40, and the loss tangent is not greater than 0.005. Thus, the electric field of the 1 / 4λ resonator is mainly concentrated in the dielectric between the open-circuit section and the grounding section, with very little external radiation and minimal influence from the outside environment. It has a good electromagnetic shielding effect and does not require an additional metal shielding cover. At the same time, the high dielectric constant of the third dielectric layer and the second dielectric layer also helps to greatly reduce the planar size of the resonator. The short-circuit section and the open-circuit section of the 1 / 4λ resonator are vertically aligned, which allows the planar size of the resonator to be further reduced. Moreover, the low loss tangent of the third dielectric layer and the second dielectric layer also results in a high Q value for the resonator.

[0025] Furthermore, in the microfilter provided in this application embodiment, both the first and second parts can be fabricated using CMOS technology and packaged at the chip level, achieving micron-level or even nanometer-level processing precision, enabling the microfilter to meet high-frequency applications. Both the first and second parts employ a multi-layer metal stacked structure, allowing for structural design of each metal layer, increasing design freedom and enabling more flexible feeding methods and coupling methods between resonators. It also facilitates the introduction of cross-coupling structures.

[0026] In summary, the microfilter provided in this application combines upper and lower parts with a multi-layer structure to form a vertical, three-dimensional multi-layer structure. By utilizing a dielectric material with a high dielectric constant and low dielectric loss coefficient to confine the electromagnetic field, the planar size of the filter can be effectively reduced, achieving low loss. This microfilter actually forms a cavity-like structure, possessing the high Q value and easy cross-coupling characteristics of cavity structures. This microfilter also has the high degree of freedom of a multi-layer structure, and the fabrication process uses semiconductor CMOS technology, possessing micron or even nanometer-level processing precision. It has great engineering application value for millimeter-wave and even higher frequency filters. In other words, this application provides a filter that is small in size, has a high Q value, low loss, and can meet the requirements of high-frequency applications. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0028] Figure 1 This is a schematic diagram of the structure of a miniature filter provided in an embodiment of this application;

[0029] Figure 2 for Figure 1 A front view of the AA' surface of the microfilter shown;

[0030] Figure 3 for Figure 1 A perspective view of the micro-filter shown.

[0031] Figure 4 for Figure 1 A schematic diagram of the structure of the metal part of the first section of the microfilter shown.

[0032] Figure 5 for Figure 1 The diagram shows the structure of the first part of the microwave filter.

[0033] Figure 6 for Figure 1 A schematic diagram of the metal portion of the second part of the microfilter shown.

[0034] Figure 7 for Figure 1 The diagram shows the structure of the second part of the micro-filter.

[0035] Figure 8 for Figure 3The diagram shows a partial structure of the miniature filter after it has been cut along the BB' section.

[0036] Figure 9 for Figure 8 A front view schematic diagram of the BB' section of a local structure of the microfilter shown;

[0037] Figure 10 A top view schematic diagram of another miniature filter provided in an embodiment of this application;

[0038] Figure 11 for Figure 10 A front view of the CC' section of the miniature filter shown;

[0039] Figure 12 This is a schematic diagram of the structure of the first part of another microfilter provided in an embodiment of this application;

[0040] Figure 13 for Figure 12 A top view of the first part of the miniature filter shown;

[0041] Figure 14 for Figure 12 and Figure 13 A front view of the DD' section of the microfilter shown;

[0042] Figure 15 A perspective view of another miniature filter provided in an embodiment of this application;

[0043] Figure 16 A top view schematic diagram of yet another miniature filter provided in an embodiment of this application;

[0044] Figure 17 for Figure 15 A top view of the miniature filter shown;

[0045] Figure 18 A top view schematic diagram of another miniature filter provided in an embodiment of this application;

[0046] Figure 19 A perspective structural schematic diagram of yet another miniature filter provided in an embodiment of this application;

[0047] Figure 20 A perspective view of another miniature filter provided in an embodiment of this application;

[0048] Figure 21 for Figure 20 A top view of the miniature filter shown;

[0049] Figure 22 for Figure 20A schematic diagram of the resonator section in the miniature filter shown;

[0050] Figure 23 for Figure 22 A schematic diagram of the resonator section along section EE' is shown;

[0051] Figure 24 for Figure 20 The simulation results of the microfilter are shown.

[0052] Figure label:

[0053] 100 - First part; 200 - Second part; 110 - First metal layer; 120 - First dielectric layer; 130 - Second metal layer; 131 - First annular portion; T1 - First metal via; 210 - Third metal layer; 220 - Second dielectric layer; 230 - Fourth metal layer; 240 - Third dielectric layer; 211 - First pad portion; 212 - Second annular portion; 231 - Ground portion; 232 - Open circuit portion; K1 - Opening; T2 - Second metal via T3 - Third metal via; 10 - 1 / 4λ resonator; 11 - Open circuit section; 12 - Short circuit section; H1 - Soldering section; 132 - Second solder pad section; T4 - Fourth metal via; L1 - Magnetic coupling connection line; P10 - Shielding wall; P11 - Shielding section; T5 - Fifth metal via; F10 - Flying rod; F11 - Coupling section; F12 - Connection section; Signal input terminal - In; Signal output terminal - Out; M1 - First tap structure; M2 - Second tap structure. Detailed Implementation

[0054] 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.

[0055] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the accompanying drawings illustrating the device structure may be partially enlarged, not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0056] Figure 1 This illustration shows a schematic diagram of the structure of a miniature filter provided in an embodiment of this application. Figure 2 It shows Figure 1 The diagram shows a front view of the AA' surface of the microfilter, combined with... Figure 1 and Figure 2As shown, the microfilter provided in this application embodiment includes a first part 100 and a second part 200 stacked together.

[0057] Combination Figure 1 and Figure 2 As shown, the first part 100 includes a first metal layer 110 and alternating layers of a first dielectric layer 120 and a second metal layer 130 located on the side of the first metal layer 110 closest to the second part 200. The first metal layer 110 closest to the second part 200 is initially the first dielectric layer 120, and the layer closest to the second part 200 in the first part 100 is the second metal layer 130. It can be understood that the first part 100 may include a stacked first metal layer 110, a first dielectric layer 120, and a second metal layer 130; that is, the first part 100 includes one set of first dielectric layers 120 and second metal layers 130, and the first part 100 includes a total of two metal layers and one dielectric layer. Alternatively, the first part 100 may include a stacked first metal layer 110, a first dielectric layer 120, a second metal layer 130, and a second metal layer 130; that is, the first part 100 includes two sets of first dielectric layers 120 and second metal layers 130. The first part 100 includes a total of three metal layers and two dielectric layers; the first part 100 may also include a first metal layer 110, a first dielectric layer 120, a second metal layer 130, a first dielectric layer 120, a second metal layer 130, and a first dielectric layer 120 and a second metal layer 130 stacked together, that is, the first part 100 includes three sets of first dielectric layers 120 and second metal layers 130, and the first part 100 includes a total of four metal layers and three dielectric layers; this application does not limit the number of combinations of first dielectric layers 120 and second metal layers 130 in the first part 100, and it can be determined according to the specific situation.

[0058] Figure 3 It shows Figure 1 The diagram shows a perspective view of the micro-filter. Figure 4 It shows Figure 1 The diagram shows the structure of the metal portion of the first part 100 in the microfilter. Figure 5 It shows Figure 1 The schematic diagram of the first part 100 in the microwave filter shown is combined with... Figures 3-5 As shown, the second metal layer 130 includes a first annular portion 131. The first metal layer 110 and the first annular portion 131 of the adjacent second metal layer 130, as well as the first annular portions 131 of two adjacent second metal layers 130, are electrically connected by a first metal through-hole T1 that penetrates the first dielectric layer 120 and is arranged in an annular pattern.

[0059] Understandably, in combination Figure 3 and Figure 4As shown, since the first metal layer 110 is grounded, and the first annular portion 131 of the first metal layer 110 and the first annular portion 131 of the adjacent second metal layer 130 and the first annular portion 131 of the two adjacent second metal layers 130 are electrically connected through the first metal via T1 that penetrates the first dielectric layer 120 and is arranged in an annular pattern, the first annular portion 131 of the second metal layer 130 and the first metal via T1 are also grounded.

[0060] It is also understandable that the first annular portion 131 of each second metal layer 130 in the first part 100 and the first metal through holes T1 arranged in a ring around it approximately constitute a metal conductor wall. Together with the grounded first metal layer 110, they form an electromagnetic shielding structure. As long as the gap width between the first metal through holes T1 is less than the wavelength of the electromagnetic wave, the electromagnetic wave will not leak from the gap between the first metal through holes T1.

[0061] Furthermore, it can be understood that during the fabrication of the first part 100, a first dielectric layer 120 is first formed on the first metal layer 110. Multiple first metal vias T1 are then formed by drilling holes in the first dielectric layer 120, followed by the formation of a second metal layer 130, and so on. Therefore, it can be considered that... Figure 4 The metal frame shown is filled with a medium, i.e. Figure 5 As shown.

[0062] Combination Figure 1 and Figure 2 As shown, the second part 200 includes a third metal layer 210, a second dielectric layer 220, a fourth metal layer 230, and a third dielectric layer 240 stacked in a direction opposite to that of the first part 100. That is, the second part 200 is a stacked structure of two metal layers and two dielectric layers. The dielectric constants of the second dielectric layer 220 and the third dielectric layer 240 are not less than 40, and the loss tangent is not greater than 0.005. We know that the dielectric constant characterizes a material's ability to store electrostatic energy in an electric field; a high dielectric constant means a stronger charge storage capacity. The loss tangent measures the energy loss efficiency of a material in an alternating electric field; the smaller the loss tangent, the less energy is lost in converting it into heat, and the better the high-frequency performance of the material.

[0063] Optionally, the materials of the second dielectric layer 220 and the third dielectric layer 240 are lithium niobate or lithium tantalate; the dielectric constant of lithium niobate is typically greater than 40, and the loss tangent is typically in the range of 0.001-0.005; the dielectric constant of lithium tantalate is typically in the range of 41-53, and the loss tangent is typically less than 0.001.

[0064] Figure 6 It shows Figure 1 The diagram shows the structure of the metal portion of the second part 200 in the microfilter. Figure 7 It shows Figure 1 The schematic diagram of the second part 200 in the micro-filter shown is combined with... Figure 3 , Figure 6 and Figure 7 As shown, the third metal layer 210 includes a first pad portion 211 and a second annular portion 212 surrounding the first pad portion 211. The fourth metal layer 230 includes a ground portion 231 and an open portion 232. The ground portion 231 has an opening K1, and the open portion 232 is located inside the opening K1. The ground portion 231 is electrically connected to the second annular portion 212 through a second metal via T2 penetrating the second dielectric layer 220. The open portion 232 is electrically connected to the first pad portion 211 through a third metal via T3 penetrating the second dielectric layer 220.

[0065] Figure 8 It shows Figure 3 The diagram shows a partial structural representation of the miniature filter after it has been cut along the BB' section. Figure 9 It shows Figure 8 The diagram shows a front view of the BB' section of a local structure of the microfilter, combined with... Figure 3 , Figure 8 and Figure 9 As shown, the microfilter includes at least one 1 / 4λ resonator 10, which includes an open-circuit portion 11 and a short-circuit portion 12, where λ is the wavelength corresponding to the operating frequency of the microfilter.

[0066] Combination Figure 3 , Figure 6 , Figure 8 and Figure 9 As shown, the open-circuit portion 11 of the 1 / 4λ resonator 10 includes an open-circuit portion 232, a third metal via T3, and a first pad portion 211. Combined with... Figure 3 , Figure 4 , Figure 8 and Figure 9 As shown, the short-circuit portion 12 is located in the first portion 100. Specifically, the short-circuit portion 12 is located in each of the first dielectric layers 120 and is surrounded by each of the first dielectric layers 120.

[0067] Combination Figures 1-9 As shown, the first annular portion 131 of the second metal layer 130 closest to the second part 200 and the second annular portion 212 of the third metal layer 210, as well as the short-circuit portion 12 and the open-circuit portion 11 of the 1 / 4λ resonator 10 are electrically connected by a welding portion H1.

[0068] As previously known, the first annular portion 131 of each second metal layer 130 in the first part 100 and each of the first metal through holes T1 arranged in a peripheral annular pattern are also grounded because they are electrically connected to the grounded first metal layer 110. Subsequently, as... Figure 9As shown, the first annular portion 131 of the second metal layer 130 of the first portion 100, which is closest to the second portion 200, is electrically connected to the second annular portion 212 of the third metal layer 210 of the second portion 200 via a welding portion H1. Furthermore, as... Figure 6 As shown, in the second part 200, the second annular portion 212 of the third metal layer 210 is electrically connected to the ground portion 231 of the fourth metal layer 230 through the second metal through hole T2, so that the ground portion 231 of the fourth metal layer 230 achieves good grounding.

[0069] It is understood that in the micro filter provided in this application embodiment, the open-circuit part 232 is the open-circuit end of the 1 / 4λ resonator 10. The open-circuit end of the resonator is the signal layer. Furthermore, the open-circuit part 232 and the ground part 231 are located in the fourth metal layer 230. That is, the signal layer (i.e., the open-circuit part 232) and the grounded metal layer (i.e., the ground part 231) of the 1 / 4λ resonator 10 are coplanarly arranged to form a coplanar waveguide structure. In this way, the electric field of the 1 / 4λ resonator 10 is mainly concentrated between the open-circuit part 232 and the ground part 231.

[0070] Furthermore, the upper and lower sides of the fourth metal layer 230 are respectively the third dielectric layer 240 and the second dielectric layer 220. It can be understood that when the third dielectric layer 240 is deposited, it fills the gap between the open portion 232 and the ground portion 231 of the fourth metal layer 230. That is, as... Figure 9 As shown, the upper side of the fourth metal layer 230 and the gap between the open portion 232 and the ground portion 231 of the fourth metal layer 230 are all third dielectric layers 240, the lower side of the fourth metal layer 230 is the second dielectric layer 220, and the dielectric constant of the third dielectric layer 240 and the second dielectric layer 220 is not less than 40, and the loss tangent is not greater than 0.005.

[0071] Thus, as Figure 9 As shown, due to the coplanar waveguide structure of the open-circuit terminal of the 1 / 4λ resonator 10, coupled with the high dielectric constant characteristics of the third dielectric layer 240 and the second dielectric layer 220 confining the electromagnetic field, the electric field of the 1 / 4λ resonator 10 (such as...) Figure 9 (As indicated by the middle arrow) The electromagnetic shielding is mainly concentrated in the dielectric between the open circuit part 232 and the ground part 231, with very little external radiation and minimal external influence, resulting in excellent electromagnetic shielding without the need for an additional metal shielding cover. At the same time, the high dielectric constant of the third dielectric layer 240 and the second dielectric layer 220 also greatly helps to reduce the planar size of the resonator. Moreover, the low loss tangent of the third dielectric layer 240 and the second dielectric layer 220 (reaching the level of commonly used high-performance microwave ceramic dielectrics) results in a very high Q value for the resonator.

[0072] The reason why the high dielectric constant third dielectric layer 240 and second dielectric layer 220 are beneficial to greatly reducing the size of the resonator is that the resonator size (such as length L) must satisfy the standing wave condition (such as 1 / 2λ or 1 / 4λ). Therefore, the operating frequency f of the resonator satisfies:

[0073] (1)

[0074] ε r It is the dielectric constant of the medium. From formula (1), we know that the dielectric constant ε of the medium is... r The higher the dielectric constant, the smaller the size of the resonator at the same operating frequency. Therefore, the high dielectric constant of the third dielectric layer 240 and the second dielectric layer 220 is beneficial to greatly reduce the size of the resonator, so that the size of the entire micro-filter can reach the millimeter level.

[0075] The materials of the third dielectric layer 240 and the second dielectric layer 220 can be lithium niobate or lithium tantalate. Lithium niobate and lithium tantalate are colorless and transparent trigonal crystals with good optical and piezoelectric properties, and are currently widely used in optical communication devices and acoustic filters. This application embodiment utilizes the high dielectric constant and low dielectric loss coefficient (low loss tangent) characteristics of lithium niobate or lithium tantalate to apply lithium niobate or lithium tantalate to microwave filters, which is an engineering practice of applying lithium niobate and lithium tantalate to microwave filters.

[0076] It is also understood that in the micro-filter provided in this application embodiment, the second part 200 mainly accommodates the open-circuit part 11 of the 1 / 4λ resonator 10 and the electric field distribution of the 1 / 4λ resonator 10. The electric field distribution of the 1 / 4λ resonator 10 is mainly concentrated in the medium between the open-circuit part 232 and the ground part 231, and is also accommodated in the shielding structure formed by the second annular part 212 of the third metal layer 210, the second metal through hole T2, and the ground part 231 of the fourth metal layer 230. The first part 100 mainly accommodates the short-circuit part 12 of the 1 / 4λ resonator 10 and the magnetic field distribution of the 1 / 4λ resonator 10. The first part 100 and the second part 200, as well as the short-circuit part 12 and the open-circuit part 11 of the 1 / 4λ resonator 10, are connected by the welding part H1. That is to say, the short-circuit part 12 and the open-circuit part 11 of the 1 / 4λ resonator 10 are vertically arranged, which allows the planar size of the resonator to be further reduced. Because if a simple planar structure is used, with the short-circuit and open-circuit terminals of the resonator distributed in the same plane, the planar size of the resonator would double. However, the embodiments of this application greatly reduce the planar size of the resonator by increasing the longitudinal dimension of the resonator slightly, and the planar size of the resonator is a primary consideration.

[0077] It is also understood that the micro-filter provided in this application embodiment adopts a 1 / 4λ resonator structure, and the 1 / 4λ resonator structure is divided into two parts, namely the open-circuit part 11 located in the first part 100 and the short-circuit part 12 located in the second part 200. Furthermore, the second part 200 adopts a stacked structure of two metal layers and two dielectric layers, and the first part 100 adopts a stacked structure of at least two metal layers and at least one dielectric layer. In this way, both the first part 100 and the second part 200 can be processed using CMOS technology and chip-level packaging, with processing accuracy reaching the micron level or even the nanometer level, so that the micro-filter meets the requirements of high-frequency applications.

[0078] Furthermore, it can be understood that in the micro-filter provided in the embodiments of this application, the first part 100 includes a first metal layer 110 and at least one second metal layer 130, and the second part 200 includes a third metal layer 210 and a fourth metal layer 230. That is, both the first part 100 and the second part 200 adopt a multi-layer metal layer stacked structure. Therefore, each metal layer can be structurally designed, which increases the degree of design freedom and enables more flexible feeding methods and coupling methods between resonators. It is also very easy to introduce cross-coupling structures.

[0079] In summary, the microfilter provided in this application combines upper and lower parts with a multi-layer structure to form a vertical, three-dimensional multi-layer structure. By utilizing a dielectric material with a high dielectric constant and low dielectric loss coefficient to confine the electromagnetic field, the planar size of the filter can be effectively reduced, achieving low loss. This microfilter actually forms a cavity-like structure, possessing the high Q value and easy cross-coupling characteristics of cavity structures. This microfilter also has the high degree of freedom of a multi-layer structure, and the fabrication process uses semiconductor CMOS technology, possessing micron or even nanometer-level processing precision. It has great engineering application value for millimeter-wave and even higher frequency filters. In other words, this application provides a filter that is small in size, has a high Q value, low loss, and can meet the requirements of high-frequency applications.

[0080] It should be noted that this is optional, combined with Figure 4 and Figure 6 As shown, the welding part H1 can be located at the four corners of the second annular part 212 of the third metal layer 210 (on the side facing the first part 100). However, this application does not limit the number and arrangement of the welding parts H1. Alternatively, the welding parts H1 can also be arranged in a ring on the side of the second annular part 212 of the third metal layer 210 facing the first part 100, depending on the specific situation.

[0081] It should also be noted that optional, such as Figure 5As shown, the second metal via T2 can be located at the four corners of the second annular portion 212 of the third metal layer 210 (on the side facing the fourth metal layer 230). However, this application does not limit the number and arrangement of the second metal via T2. Alternatively, the second metal via T2 can also be arranged in a ring on the side of the second annular portion 212 of the third metal layer 210 facing the fourth metal layer 230, depending on the specific situation.

[0082] It should also be noted that this application does not limit the shape of the microfilter, such as Figures 1-9 As shown, the top view of the microfilter can be square; however, it can also be circular or other shapes, depending on the specific circumstances. Similarly, this application does not limit the shape of the open circuit portion 232 or the shape of the opening K1 where the open circuit portion 232 is located. Figure 3 and Figure 6 As shown, the shape of the opening portion 232 and the shape of the opening K1 where the opening portion 232 is located can be circular. Of course, the shape of the opening portion 232 and the shape of the opening K1 where the opening portion 232 is located can also be square or other shapes, depending on the specific situation.

[0083] It should also be noted that the short-circuit portion 12 of the 1 / 4λ resonator 10 is considered as a whole and is mainly used to generate a magnetic field. Optionally, the short-circuit portion 12 of the 1 / 4λ resonator 10 can be a cylinder.

[0084] Alternatively, considering that the first portion 100 includes a first metal layer 110 and alternating layers of a first dielectric layer 120 and a second metal layer 130 located on the side of the first metal layer 110 near the second portion 200, and that the first annular portions 131 of the first metal layer 110 and adjacent second metal layers 130, as well as the first annular portions 131 of adjacent second metal layers 130, are electrically connected through first metal vias T1 arranged in annular patterns through the first dielectric layer 120, therefore, as Figure 4 and Figure 9 As shown, the short-circuit portion 12 of the 1 / 4λ resonator 10 may include a second pad portion 132 located in each of the second metal layers 130, and adjacent second pad portions 132 are electrically connected through a fourth metal via T4 penetrating the first dielectric layer 120.

[0085] It is understood that each second metal layer 130 includes a second pad portion 132 and a first annular portion 131 surrounding the second pad portion 132. The second pad portion 132 and the first annular portion 131 located in the same second metal layer 130 can be formed simultaneously. Furthermore, the first metal via T1 and the fourth metal via T4 penetrating the same first dielectric layer 120 can also be formed simultaneously.

[0086] Thus, the short-circuit portion 12 of the 1 / 4λ resonator 10 is also a multi-layer structure, which increases the design freedom, allows for more flexible feeding methods and coupling methods between resonators, and is also easier to implement in terms of manufacturing process.

[0087] Figures 1-9 The example provided in this application is a micro-filter that includes a 1 / 4λ resonator. In practical applications, micro-filters typically include at least two 1 / 4λ resonators. Furthermore, since each 1 / 4λ resonator is both a three-dimensional structure and a multi-layer structure, various coupling methods can be achieved between different 1 / 4λ resonators. This makes it very easy to apply cross-coupling technology, which can improve the suppression performance of the filter. The following is a detailed explanation.

[0088] The first type of magnetic coupling:

[0089] Figure 10 This illustration shows a top view of another miniature filter provided in an embodiment of this application. Figure 11 It shows Figure 10 The diagram shows a front view of the CC' section of the miniature filter. For clarity, the diagram is shown below. Figure 10 and Figure 11 Only the structure of the 1 / 4λ resonator 10 is shown. As previously known, since the open-circuit end of the 1 / 4λ resonator is a coplanar waveguide structure, coupled with the electromagnetic confinement effect of the high-dielectric-constant second dielectric layer 220 and third dielectric layer 240, the electric field of the 1 / 4λ resonator is mainly concentrated between the open-circuit part 232 and the surrounding ground part 231. Thus, as... Figure 10 and Figure 11 As shown, there is almost no coupling between the open ends of the two 1 / 4λ resonators 10, and the electrical coupling can be considered to be zero; while the coupling between the two 1 / 4λ resonators 10 is achieved through the magnetic field generated by the short-circuit portion 12 of the two 1 / 4λ resonators 10, that is, the coupling between the two 1 / 4λ resonators 10 is purely magnetic, and the magnetic coupling strength can be controlled by controlling the distance between the two 1 / 4λ resonators 10.

[0090] The second type of magnetic coupling:

[0091] Understandably, the first method controls the magnetic coupling of the two 1 / 4λ resonators by adjusting the distance between them, resulting in a relatively small magnetic coupling. However, achieving broadband or even ultra-wideband connectivity requires a much larger magnetic coupling between the resonators, which cannot be achieved simply by reducing the distance between them, nor can the two 1 / 4λ resonators be placed too close together. In this case, the second coupling method can be used.

[0092] Figure 12This illustration shows a schematic diagram of the structure of the first part 100 in another microfilter provided in an embodiment of this application. Figure 13 It shows Figure 12 The diagram shows a top view of the first part 100 of the miniature filter. Figure 12 and Figure 13 The second part 200 of the miniature filter shown is as follows Figure 14 As shown, Figure 14 It shows Figure 12 and Figure 13 The diagram shows a front view of the DD' section of the miniature filter. For clarity, the diagram is shown below. Figure 12 and Figure 13 The diagram mainly illustrates the short-circuit portions 12 of the two 1 / 4λ resonators 10. Combined with... Figures 12-14 As shown, the second magnetic coupling method involves setting a magnetic coupling connection line L1. That is, the first part 100 also includes a magnetic coupling connection line L1. The magnetic coupling connection line L1 connects the second pad portion 132 of the first layer of the two 1 / 4λ resonators 10. In other words, the second pad portion 132 of either layer of the two 1 / 4λ resonators 10 is connected by the magnetic coupling connection line L1, thereby connecting the short-circuit portion 12 of the two 1 / 4λ resonators 10 and increasing the magnetic coupling between the two 1 / 4λ resonators 10.

[0093] It should be noted that the closer the second pad portion 132 of the two 1 / 4λ resonators 10 connected by the magnetic coupling connection line L1 in the first part 100 is to the second part 200, the greater the magnetic coupling between the two 1 / 4λ resonators 10. That is, when the magnetic coupling connection line L1 is located in the second metal layer 130 closest to the first metal layer 110 and connects the second pad portion 132 of the two 1 / 4λ resonators 10 in the second metal layer 130, the magnetic coupling between the two 1 / 4λ resonators 10 is minimized. When the magnetic coupling connection line L1 is located in the second metal layer 130 closest to the second part 200 and connects the second pad portion 132 of the two 1 / 4λ resonators 10 in the second metal layer 130, the magnetic coupling between the two 1 / 4λ resonators 10 is maximized.

[0094] It should also be noted that the magnetic coupling between the two 1 / 4λ resonators 10 can be adjusted by changing the length of the magnetic coupling connection line L1. The longer the magnetic coupling connection line L1 is, the greater the magnetic coupling between the two 1 / 4λ resonators 10.

[0095] This verifies that the micro-filter provided in this application embodiment has a multi-layer three-dimensional structure in its first part 100, which makes the coupling between resonators more diverse and the adjustment methods more flexible.

[0096] The previous section explained two magnetic coupling methods between resonators; the next section will explain the electrical coupling methods between resonators.

[0097] Figure 15 This illustration shows a perspective view of another micro-filter provided in an embodiment of this application. For clarity, the structure of the 1 / 4λ resonator 10 is primarily shown. Figure 15 As shown, in order to achieve pure electrical coupling between the two 1 / 4λ resonators 10, a shielding wall P10 needs to be set between the two 1 / 4λ resonators 10. That is, the first part 100 also includes a shielding wall P10 located between the two 1 / 4λ resonators 10. The shielding wall P10 includes a shielding part P11 located in each of the second metal layers 130, and a plurality of fifth metal through holes T5 that penetrate the first dielectric layer 120 to connect the shielding parts P11 of the two adjacent layers. This isolates the magnetic field between the short-circuit parts 12 of the two 1 / 4λ resonators 10, so that there is no magnetic coupling between the two 1 / 4λ resonators 10.

[0098] It is understandable that the shielding wall P10 formed by the shielding portion P11 located in each of the second metal layers 130 and the plurality of fifth metal through holes T5 that penetrate the first dielectric layer 120 and connect the two adjacent shielding portions P11 is similar to the metal conductor wall formed by the first annular portion 131 of each of the second metal layers 130 and the plurality of first metal through holes T1 that penetrate the first dielectric layer 120 and connect the two adjacent first annular portions 131, and has a shielding effect on electromagnetic fields.

[0099] Based on this, the following describes three electrical coupling methods between resonators.

[0100] The first type of electrical coupling:

[0101] Figure 16 This illustration shows a top view of yet another microfilter provided in an embodiment of this application, as shown below. Figure 16 As shown, the first type of electrical coupling involves connecting the openings K1 where the open portions 232 of the two 1 / 4λ resonators 10 are located. In this way, there is an electric field between the open portions 232 of the two 1 / 4λ resonators 10, which can achieve electrical coupling.

[0102] The second type of electrical coupling:

[0103] To further improve the electrical coupling between the two 1 / 4λ resonators 10, based on the first electrical coupling method, and combining... Figure 15 and Figure 17 As shown, Figure 17 It shows Figure 15 The diagram shown is a top view of a miniature filter. Figure 17The shielding wall P10 is not shown. It can be seen that a flying rod F10 can be set in the two connected openings K1. The flying rod F10 includes two coupling parts F11 and one connecting part F12. The two coupling parts F11 partially surround the open part 232 of the two 1 / 4λ resonators 10, that is, one coupling part F11 partially surrounds the open part 232 of one 1 / 4λ resonator 10, and the other coupling part F11 partially surrounds the open part 232 of the other 1 / 4λ resonator 10. The connecting part F12 connects the two coupling parts F11.

[0104] It is understandable that, since the open circuit portion 232 of the fly rod F10 and the fly rod F10 are not connected when the two 1 / 4λ resonators 10 are electrically coupled through the above-mentioned fly rod F10, this fly rod F10 form is very suitable for realizing the electrical coupling between non-adjacent 1 / 4λ resonators, that is, realizing the cross electrical coupling between non-adjacent 1 / 4λ resonators.

[0105] The third type of electrical coupling:

[0106] To further improve the electrical coupling between the two 1 / 4λ resonators 10, based on the first electrical coupling method, such as... Figure 18 As shown, Figure 18 This illustration shows a top view of yet another miniature filter provided in an embodiment of this application. Figure 18 The shielding wall P10 is not shown. It can be seen that the open parts 232 of the two 1 / 4λ resonators 10 in the two connected openings K1 form an interdigital structure. This type of electrically coupled micro-filter is suitable for broadband and ultra-wideband applications.

[0107] The above describes the magnetic and electrical coupling methods between two resonators in a microfilter. In practical applications, both magnetic and electrical coupling can coexist, resulting in hybrid electromagnetic coupling. This coupling method can create a transmission zero outside the band, improving out-of-band rejection. It is understandable that the two magnetic coupling methods and three electrical coupling methods between the two 1 / 4λ resonators 10 can be arbitrarily combined. However, when the two 1 / 4λ resonators 10 are hybrid electromagnetically coupled, a shielding wall P10 is not required between the short-circuited portions 12 of the two 1 / 4λ resonators 10.

[0108] Furthermore, it is understood that since the electrical coupling of the two 1 / 4λ resonators 10 is distributed in the second part 200, while the magnetic coupling of the two 1 / 4λ resonators 10 is distributed in the first part 100, the electrical and magnetic coupling of the two 1 / 4λ resonators 10 can be independently controlled, which is very convenient for controlling the out-of-band zero position.

[0109] An electromagnetic hybrid coupling method:

[0110] Figure 19 This illustration shows a perspective structural diagram of yet another microfilter provided in an embodiment of this application, as shown below. Figure 19 As shown, this miniature filter not only connects the two second pads 132 of the two 1 / 4λ resonators 10 located on the same layer through a magnetic coupling connection line L1 to achieve magnetic coupling between the two 1 / 4λ resonators 10, but also connects the openings K1 where the open circuits 232 of the two 1 / 4λ resonators 10 are located. A flying rod F10 is set in the two connected openings K1 to achieve electrical coupling between the two 1 / 4λ resonators 10. In this way, hybrid electromagnetic coupling is achieved, and the electrical coupling and magnetic coupling of the two 1 / 4λ resonators 10 can be controlled independently.

[0111] In summary, when the micro-filter provided in this application includes at least two 1 / 4λ resonators, since the 1 / 4λ resonators are a combination of three-dimensional and multi-layer structures, they can achieve electrical coupling, magnetic coupling, and electromagnetic hybrid coupling. Furthermore, the electrical coupling and magnetic coupling can be controlled independently, making it very easy to apply the cross-coupling theory.

[0112] Figure 20 This illustration shows a perspective view of another microfilter provided in an embodiment of this application. Figure 21 It shows Figure 20 The diagram shown is a top view of a miniature filter. Figure 22 It shows Figure 20 The diagram shown is a schematic of the resonator section in the miniature filter. Figure 23 It shows Figure 22 The schematic diagram shown is of the resonator section along cross section EE', combined with... Figures 20-23As shown, this miniature filter includes six 1 / 4λ resonators: resonator 1, resonator 2, resonator 3, resonator 4, resonator 5, and resonator 6. Non-adjacent resonators 1 and 4 are connected by a cross-coupling with electrical polarity via a flybar F10. A shielding wall P10 isolates the magnetic coupling between resonators 1 and 4, as well as the parasitic coupling between resonators 1 and 3, and between resonators 1 and 5. Other adjacent resonators are magnetically coupled, resulting in magnetic coupling as the primary coupling of this miniature filter. The coupling patterns are: resonator 1-resonator 2-resonator 3-resonator 4-resonator 1 and resonator 1-resonator 4-resonator 5-resonator... Resonator 6 and resonator 1 respectively form two cascaded quadruple (CQ) structures, generating four symmetrical transmission zeros. Furthermore, the signal input terminal In and signal output terminal Out of this miniature filter are on the same layer as the grounded first metal layer 110. The second pad portion 132 of the first layer of resonator 1 is electrically connected to the signal input terminal In through the first tap structure M1, and the second pad portion 132 of the first layer of resonator 6 is electrically connected to the signal output terminal Out through the second tap structure M2, forming a tap-fed structure to realize signal input and output. This miniature filter is a 6th-order four-zero bandpass filter with an overall size of only 3mm×4mm×0.9mm, approximately 0.1λ×0.1λ.

[0113] It should be noted that this application does not limit the feeding method of the microfilter, that is, the feeding method of the microfilter is not limited to the above-mentioned tap feeding method, and other feeding methods are also applicable.

[0114] Figure 24 It shows Figure 20 The simulation results of the microfilter shown are combined with Figures 20-24 As shown, the above-mentioned 6th-order four-zero bandpass filter has a center frequency of 6925MHz, a bandwidth of 400MHz, and a relative bandwidth of 5.7%. Zeros 1 and 2 are generated by a CQ structure consisting of resonator 1-resonator 2-resonator 3-resonator 4-resonator 1, and zeros 3 and 4 are generated by a CQ structure consisting of resonator 1-resonator 4-resonator 5-resonator 6-resonator 1. Furthermore, it has an insertion loss of 1.235dB at the center frequency of 6925MHz, exhibiting low insertion loss, symmetrical distribution of four zeros outside the band, high out-of-band rejection, high rectangularity, and excellent performance.

[0115] Furthermore, embodiments of this application also provide an electronic device that includes the microfilter described in any of the foregoing embodiments. Since the microfilter has been described in detail in the foregoing embodiments, it will not be repeated here.

[0116] The various parts of this manual are described in a combination of parallel and progressive methods. Each part focuses on the differences between the other parts, and the same or similar parts can be referred to each other.

[0117] The features described above regarding the disclosed embodiments can be substituted or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A miniature filter, characterized in that, The microfilter comprises a first part and a second part stacked together. The first part includes a first metal layer and a first dielectric layer and a second metal layer that are alternately stacked on the side of the first metal layer near the second part. The first metal layer is grounded. The layer of the first part closest to the second part is the second metal layer. The second metal layer includes a first annular portion. The first metal layer and the first annular portion of the adjacent second metal layer and the first annular portions of two adjacent second metal layers are electrically connected through a first metal via that penetrates the first dielectric layer and is arranged in an annular pattern. The second part includes a third metal layer, a second dielectric layer, a fourth metal layer, and a third dielectric layer stacked in a direction opposite to the first part. The third metal layer includes a first pad portion and a second annular portion surrounding the first pad portion. The fourth metal layer includes a ground portion and an open-circuit portion. The ground portion has an opening, and the open-circuit portion is located within the opening. The ground portion is electrically connected to the second annular portion through a second metal via penetrating the second dielectric layer. The open-circuit portion is electrically connected to the first pad portion through a third metal via penetrating the second dielectric layer. The dielectric constant of the second dielectric layer and the third dielectric layer is not less than 40, and the loss tangent is not greater than 0.

005. The microfilter includes at least one 1 / 4λ resonator, which includes an open-circuit portion and a short-circuit portion. The open-circuit portion includes the open section, the third metal via, and the first pad section. The short-circuit portion is located in the first section and is located in each of the first dielectric layers and is surrounded by each of the first annular portions. The first annular portion of the first part closest to the second part of the second metal layer and the second annular portion are electrically connected by a welding part, as are the short-circuit portion and the open-circuit portion.

2. The microfilter according to claim 1, characterized in that, The materials of the second dielectric layer and the third dielectric layer are lithium niobate or lithium tantalate.

3. The microfilter according to claim 1, characterized in that, The short-circuit portion includes a second pad portion located in each of the second metal layers, and adjacent second pad portions are electrically connected through a fourth metal via penetrating the first dielectric layer.

4. The microfilter according to claim 3, characterized in that, The microfilter includes at least two of the 1 / 4λ resonators.

5. The microfilter according to claim 4, characterized in that, The first part also includes a magnetic coupling connection line that connects the second pad portion of one layer of the two 1 / 4λ resonators.

6. The microfilter according to claim 4, characterized in that, The first part also includes a shielding wall located between the two 1 / 4λ resonators, the shielding wall including shielding portions located in each of the second metal layers, and a plurality of fifth metal through holes penetrating the first dielectric layer to connect the shielding portions of adjacent two layers.

7. The microfilter according to any one of claims 4-6, characterized in that, The openings where the open sections of the two 1 / 4λ resonators are located are connected.

8. The microfilter according to claim 7, characterized in that, A flying rod is provided in the two connected openings. The flying rod includes two coupling parts and a connecting part. One coupling part surrounds the open circuit part of one of the 1 / 4λ resonators, and the other coupling part surrounds the open circuit part of another 1 / 4λ resonator. The connecting part connects the two coupling parts.

9. The microfilter according to claim 7, characterized in that, Within the two interconnected openings, the open portions of the two 1 / 4λ resonators form an interdigitated structure.

10. An electronic device, characterized in that, Includes the microfilter as described in any one of claims 1-9.

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