High-selectivity low-loss ceramic dielectric microcavity band-pass filter

Abstract

The utility model discloses a kind of high-selectivity low-loss porcelain medium microcavity band-pass filter, it is related to filter technical field, comprising: upper and lower two layers of mirror image symmetry distribution filter unit, two layers The filter unit includes the first metal layer, intermediate substrate and second metal layer sequentially arranged from outside to inside;The second metal layer is with resonance unit;The gap region between the circumferential metal region and resonance unit directly opposite the second metal layer, the intermediate substrate is opened with the channel that passes through itself, air can be entered in the channel.The intermediate substrate uses high-dielectric ceramic substrate.This scheme is adopted, by slotting, to replace air with medium on the magnetic field propagation path, so as to reduce the medium loss of filter, reach the purpose of insertion loss reduction.

Description

Technical Field

[0001] This utility model relates to the field of filter technology, specifically to a high-selectivity, low-loss ceramic microcavity bandpass filter. Background Technology

[0002] A bandpass filter is an electronic circuit or signal processing algorithm that allows signals within a specific frequency range (called the passband) to pass through while attenuating (or blocking) all other frequency signals outside the passband range (called the stopband).

[0003] In traditional metal cavity bandpass filters, ordinary metal dielectric filters have poor temperature stability, the skin effect of the metal surface leads to ohmic loss, dielectric loss increases, and the Q value in the high-frequency band is insufficient. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention aims to provide a highly selective, low-loss ceramic microcavity bandpass filter. By using this solution, slotting is used to replace the medium in the magnetic field propagation path with air, thereby reducing the filter's dielectric loss and achieving the goal of reducing insertion loss.

[0005] This utility model is achieved through the following technical solution:

[0006] A highly selective, low-loss ceramic microcavity bandpass filter, comprising:

[0007] The filter units are distributed in two mirror-symmetric layers. Each filter unit includes a first metal layer, an intermediate substrate, and a second metal layer arranged sequentially from the outside to the inside. The second metal layer has a resonant unit.

[0008] The intermediate substrate has a channel that extends through itself, which is located in the gap between the circumferential metal region of the second metal layer and the resonant unit, and air can enter the channel.

[0009] Compared to existing technologies that employ ordinary metal dielectric filters, which suffer from poor temperature stability, ohmic losses due to the skin effect on the metal surface, increased dielectric loss, and insufficient Q-value in the high-frequency band, this invention provides a highly selective, low-loss ceramic microcavity bandpass filter. This solution utilizes slotting to replace the dielectric in the magnetic field propagation path with air, thereby reducing the filter's dielectric loss and achieving lower insertion loss. Specifically, the design includes two mirror-symmetrically distributed filter units, each comprising a first metal layer, an intermediate substrate, and a second metal layer. Therefore, this ceramic microcavity bandpass filter consists of six layers, with the upper and lower three layers mirror-symmetrically arranged. A through-channel is formed on the intermediate substrate, running along the gap between the circumferential metal region of the second metal layer and the resonant unit. The two ends of the channel connect to the input and output ports on both sides of the second metal layer. This creates a microcavity structure between the upper and lower first metal layers, allowing air to enter and replace the dielectric in the magnetic field propagation path, thus reducing the filter's dielectric loss and lowering insertion loss.

[0010] To further optimize the design, since traditional metal cavity filters are large and heavy, making it difficult to meet the miniaturization requirements of modern equipment, this solution reduces the filter size by using a high-dielectric ceramic substrate as the intermediate substrate. Microwave dielectric ceramic materials, due to their unique fabrication process, exhibit a high dielectric constant due to their crystal structure, which helps reduce the filter's size and achieve miniaturization of microwave dielectric filters, thus meeting the urgent need for component integration in modern electronic technology.

[0011] Furthermore, the second metal layer has input / output ports on both sides.

[0012] Furthermore, solder pads are provided at the input / output ports.

[0013] In a further optimization, the first metal layer is a metal shielding layer.

[0014] In a further optimization, the metal shielding layer and the intermediate substrate are bonded together using gold-tin soldering. In this solution, after the intermediate substrate and the second metal layer are processed using thin film drilling, sputtering, and photolithography techniques, the thin film filter is bonded to the metal shielding layer using gold-tin soldering.

[0015] To further optimize the system and achieve effective grounding and shielding, several metallized vias penetrating the intermediate substrate are formed in the circumferential metal region of the second metal layer. These metallized vias connect the first and second metal layers.

[0016] In a further optimization, several of the metallized vias are evenly distributed along the circumference of the intermediate substrate.

[0017] To further optimize the design, in order to make the upper and lower filter units more closely contact each other and form a whole, and to make the microcavity structure more uniform, it is not necessary to use structures such as bonding balls. The hot-press bonding can be performed directly on the second metal layer. The upper filter unit has a reserved bonding area on its inner side, and the upper and lower filter units are connected by hot-press bonding through two second metal layers.

[0018] With further optimization, the operating frequency of the ceramic microcavity bandpass filter is 12.5 GHz to 14.5 GHz.

[0019] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0020] 1. This utility model provides a highly selective, low-loss ceramic microcavity bandpass filter. By using this solution, the medium in the magnetic field propagation path is replaced with air through slotting, thereby reducing the dielectric loss of the filter and achieving the purpose of reducing insertion loss. The ceramic microcavity filter is based on thin film fabrication technology, with low insertion loss, high rectangularity coefficient, and better performance, especially with significant advantages in the high-frequency field.

[0021] 2. This utility model provides a highly selective, low-loss ceramic microcavity bandpass filter. Due to the special preparation process of the microwave dielectric ceramic material, the crystal phase structure formed has a high dielectric constant. Compared with traditional metal cavity bandpass filters, it has a smaller volume and lighter weight, which is more in line with the trend of product miniaturization. Compared with ordinary dielectric filters, it has higher temperature stability and higher Q value in the high-frequency band. Compared with ordinary thin film filters, it has a built-in metal shielding cavity, which replaces the medium in the magnetic field propagation path with air, thus reducing insertion loss. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the structure of the lower-level filtering unit provided by this utility model;

[0024] Figure 2 A schematic diagram of the overall structure of the ceramic microcavity bandpass filter provided by this utility model;

[0025] Figure 3 Simulation results of the ceramic microcavity bandpass filter provided by this utility model.

[0026] The attached diagram shows the markings and corresponding component names:

[0027] 1-Metal layer, 2-Intermediate substrate, 201-Channel, 202-Metalized via, 3-Second metal layer, 301-Resonant unit, 302-Circumferential metal region, 303-Input / output port. Detailed Implementation

[0028] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other embodiments, well-known structures, circuits, materials, or methods are not specifically described in order to avoid obscuring the present invention.

[0029] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] In the description of this utility model, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this utility model.

[0031] Example:

[0032] This embodiment provides a highly selective, low-loss ceramic microcavity bandpass filter, such as... Figures 1-3 As shown, it includes:

[0033] The filter units are distributed in two mirror-symmetric layers. Each of the two filter units includes a first metal layer 1, an intermediate substrate 2, and a second metal layer 3 arranged sequentially from the outside to the inside. The second metal layer 3 has a resonant unit 301.

[0034] In the gap region between the circumferential metal region 302 of the second metal layer 3 and the resonant unit 301, the intermediate substrate 2 has a channel 201 that passes through it, and air can enter the channel 201.

[0035] Compared to existing technologies that employ ordinary metal dielectric filters, which suffer from poor temperature stability, ohmic losses due to the skin effect on the metal surface, increased dielectric losses, and insufficient Q-value in the high-frequency band, this invention provides a highly selective, low-loss ceramic microcavity bandpass filter. This design utilizes slotting to replace the dielectric in the magnetic field propagation path with air, thereby reducing the filter's dielectric loss and achieving lower insertion loss. Specifically, the design includes two mirror-symmetrically distributed filter units, each comprising a first metal layer 1, an intermediate substrate 2, and a second metal layer 3. Therefore, this ceramic microcavity bandpass filter consists of a total of six layers, with the upper and lower three layers being mirror-symmetrical. In this design, a through channel 201 is formed on the intermediate substrate 2. The channel 201 is arranged along the gap between the circumferential metal region 302 of the second metal layer 3 and the resonant unit 301. The two ends of the channel 201 are respectively connected to the input and output ports on both sides of the second metal layer 3. In this way, a microcavity structure is formed between the upper first metal layer 1 and the lower first metal layer 1 in the ceramic microcavity bandpass filter. Air enters into the microcavity structure, thereby replacing the medium in the magnetic field propagation path with air, so as to reduce the dielectric loss of the filter and achieve the purpose of reducing insertion loss.

[0036] Furthermore, since traditional metal cavity filters are large and heavy, making it difficult to meet the miniaturization requirements of modern equipment, this solution aims to reduce the filter size by using a high-dielectric ceramic substrate as the intermediate substrate 2. Microwave dielectric ceramic materials, due to their unique fabrication process, exhibit a high dielectric constant in their crystal structure, which helps reduce the filter's size and achieve miniaturization of the microwave dielectric filter, thus meeting the urgent need for component integration in modern electronic technology.

[0037] In this embodiment, the second metal layer 3 has input / output ports on both sides.

[0038] In this embodiment, solder pads are provided at the input / output ports.

[0039] In this embodiment, the first metal layer 1 is a metal shielding layer.

[0040] In this embodiment, the metal shielding layer and the intermediate substrate 2 are bonded together using gold-tin soldering. In this scheme, after the intermediate substrate 2 and the second metal layer 3 are processed using thin-film drilling, sputtering, and photolithography techniques, the thin-film filter is bonded to the metal shielding layer using gold-tin soldering.

[0041] In this embodiment, to achieve good grounding and shielding, a plurality of metallized vias 202 penetrating the intermediate substrate 2 are formed on the circumferential metal region 302 of the second metal layer 3. The metallized vias 202 connect the first metal layer 1 and the second metal layer 3.

[0042] In this embodiment, a plurality of the metallized through holes 202 are evenly distributed along the circumference of the intermediate substrate 2.

[0043] In this embodiment, in order to make the upper and lower filter units more closely contact each other and form a whole, and to make the microcavity structure more uniform, there is no need to use bonding balls or other structures. The hot-press bonding can be performed directly on the second metal layer 3. The upper filter unit has a reserved bonding area on its inner side, and the upper and lower filter units are connected by hot-press bonding through two second metal layers 3.

[0044] In this embodiment, the operating frequency of the ceramic microcavity bandpass filter is 12.5 GHz to 14.5 GHz.

[0045] Specifically, this solution primarily reduces the dielectric loss of the filter and achieves lower insertion loss by drilling holes and slots in the high-dielectric ceramic substrate to replace the dielectric in the magnetic field propagation path with air. The technical principle is as follows:

[0046] (1) Principle of reducing dielectric loss: Under the action of an alternating electric field, the internal dipole reversal friction and ion displacement hysteresis of the dielectric will generate heat energy consumption, and its power loss is:

[0047]

[0048] in The dielectric loss tangent, The relative permittivity, For electric field strength, This represents the volume of the medium.

[0049] air ≈10 -5 Nearly lossless, the loss tangent of the ceramic dielectric is approximately 10°. -3 After replacing with air, the dielectric loss term →0.

[0050] (2) Principle of conductor loss reduction: The skin effect of the metal surface leads to ohmic loss, the power of which is:

[0051]

[0052] in The tangential magnetic field strength on the metal surface. Due to surface resistance, ceramics with high relative permittivity concentrate the electric field within the dielectric, resulting in a magnetic field near the metal wall. The relative permittivity of air is approximately 1, which enhances the magnetic field distribution within the cavity, making it more uniform and reducing the magnetic field near the metal walls. → Decrease .

[0053] (3) Q value increases:

[0054]

[0055]

[0056] ;

[0057] Improve → Reduce filter insertion loss: .

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A highly selective, low-loss ceramic microcavity bandpass filter, characterized in that, include: The filter units are distributed in two mirror-symmetric layers. Each filter unit includes a first metal layer (1), an intermediate substrate (2), and a second metal layer (3) arranged sequentially from the outside to the inside. The second metal layer (3) has a resonant unit (301). In the gap area between the circumferential metal region (302) of the second metal layer (3) and the resonant unit (301), the intermediate substrate (2) has a channel (201) that passes through it, and air can enter the channel (201).

2. The high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 1, characterized in that, The intermediate substrate (2) is a high-dielectric ceramic substrate.

3. The highly selective, low-loss ceramic microcavity bandpass filter according to claim 1, characterized in that, The second metal layer (3) has input / output ports (303) on both sides.

4. The highly selective, low-loss ceramic microcavity bandpass filter according to claim 3, characterized in that, The input / output ports are equipped with solder pads.

5. A high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 1, characterized in that, The first metal layer (1) is a metal shielding layer.

6. A high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 5, characterized in that, The metal shielding layer and the intermediate substrate (2) are bonded together by gold and tin.

7. A high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 1, characterized in that, On the circumferential metal region (302) of the second metal layer (3), a plurality of metallized through holes (202) penetrating the intermediate substrate (2) are formed.

8. A high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 7, characterized in that, A plurality of the metallized vias (202) are evenly distributed along the circumference of the intermediate substrate (2).

9. A high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 1, characterized in that, The upper filter unit has a reserved bonding area on its inner side, and the upper and lower filter units are connected by hot-pressing two second metal layers (3).

10. A high-selectivity, low-loss ceramic microcavity bandpass filter according to claim 1, characterized in that, The ceramic microcavity bandpass filter operates at a frequency of 12.5 GHz to 14.5 GHz.

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