阅读说明：本技术 滤波器及无线通信系统 (Filter and wireless communication system ) 是由 饶云博 钱慧珍 罗讯 于 2020-12-15 设计创作，主要内容包括：本申请公开一种滤波器及无线通信系统,所述滤波器包括：依次层叠设置的第一金属层、第一电路层、第二电路层、第三电路层和第二金属层；第一电路层、第二电路层和第三电路层均包含电路结构区域及围绕电路结构区域的侧边封装区,各层电路结构区域平行且叠层设置形成核心电路区；其中,第一电路层为馈线层,第二电路层设置有接地谐振器,第三电路层设置有阶跃阻抗谐振器；核心电路区设置在第一金属层与第二金属层以及侧边封装区域围成密闭腔体中；侧边封装区还设置有输入和输出端口,核心电路区连接输入和输出端口。采用前述的结构,通过密闭腔体隔离电磁辐射的干扰,减少滤波器的辐射损失,且核心电路采用叠层的设计结构,可减少滤波器的体积。(The application discloses wave filter and wireless communication system, the wave filter includes: the circuit comprises a first metal layer, a first circuit layer, a second circuit layer, a third circuit layer and a second metal layer which are sequentially stacked; the first circuit layer, the second circuit layer and the third circuit layer respectively comprise a circuit structure area and a side edge packaging area surrounding the circuit structure area, and the circuit structure areas are parallel and are arranged in a laminated mode to form a core circuit area; the first circuit layer is a feeder layer, the second circuit layer is provided with a grounding resonator, and the third circuit layer is provided with a step impedance resonator; the core circuit area is arranged in a closed cavity formed by the first metal layer, the second metal layer and the side edge packaging area in a surrounding manner; the side edge packaging area is also provided with an input port and an output port, and the core circuit area is connected with the input port and the output port. By adopting the structure, the interference of electromagnetic radiation is isolated by the closed cavity, the radiation loss of the filter is reduced, and the volume of the filter can be reduced by adopting the laminated design structure of the core circuit.)

1. A filter, comprising: the circuit comprises a first metal layer, a first circuit layer, a second circuit layer, a third circuit layer and a second metal layer which are sequentially stacked;

the first circuit layer, the second circuit layer and the third circuit layer respectively comprise a circuit structure area and a side edge packaging area surrounding the circuit structure area, and the circuit structure areas are arranged in parallel and in a laminated mode to form a core circuit area of the filter; the first circuit layer is a feeder layer, the second circuit layer is provided with a grounding resonator, and the third circuit layer is provided with a step impedance resonator;

the first metal layer, the second metal layer and the side edge packaging area form a closed cavity in a surrounding mode, and the core circuit area is arranged in the closed cavity;

the side edge packaging area is also provided with an input port and an output port, and the core circuit area is connected with the input port and the output port.

2. The filter of claim 1, wherein the side encapsulation area is provided with a plurality of through holes, the first and second metal layers and the side encapsulation area are connected by metal posts inserted through holes, and the 3-layer circuit structures of the first, second and third circuit layers are connected by metal posts.

3. The filter of claim 1, wherein the feeder shape, the ground resonator shape, or the stepped-impedance resonator shape of the feeder layer is a U-shape, an L-shape, a C-shape, or a spiral shape.

4. The filter of claim 1, wherein the circuit structure of the first circuit layer is a symmetrically disposed U-shaped feeder layer, the circuit structure of the second circuit layer is a one-quarter wavelength ground resonator, and the circuit structure of the third circuit layer is a one-quarter wavelength stepped-impedance resonator.

5. The filter of claim 1, wherein the input and output ports are connected to a feeder layer by stripline connections.

6. The filter of claim 1, wherein the coupling between circuit structures in the core circuit region comprises a strong coupling and a weak coupling, the strong coupling comprising coupling between circuit structures in adjacent layers of the core circuit region and coupling between vias of the grounded resonator; the weak coupling includes a horizontal coupling of the feeder layer and a coupling between the cross-layer circuit structures of the core circuit area.

7. The filter of claim 1, wherein the first and second metal layers are ground metals.

8. The filter of claim 1, wherein the filter has a rectangular three-dimensional structure, and the sealed cavity in which the core circuit region is located fixes the circuit structure in the core circuit region by medium filling.

9. A wireless communication system, characterized in that the wireless communication system comprises a filter according to any of claims 1-8.

10. The wireless communication system according to claim 9, wherein the wireless communication system further comprises a millimeter wave chip and an antenna, the filter is connected to the millimeter wave chip and the antenna through interconnection lines, and the filter, the millimeter wave chip and the antenna are integrated in the same PCB.

Technical Field

The present application relates to the field of band pass filter technology, and in particular, to a filter and a wireless communication system.

Background

With the implementation and application of the 5 th generation wireless communication technology, a high-performance miniaturized package assembly is crucial to meet the increasing demand of 5G communication infrastructure (e.g., base station, terminal, internet of things, etc.). The band-pass filter is a key component in a wireless communication system, and plays a role in frequency selection and spurious signal suppression in the wireless communication system. In a wireless communication system, various communication standards are often integrated, and different communication standards require filters of different frequency bands. For the development of wireless communication systems in the 5G millimeter wave band, the demand for filters in this band is gradually increasing. However, the present millimeter wave filters are mainly on-chip filters and waveguide filters. In which the on-chip filter is small in size, but the processing cost is too high and the high loss limits the difficulty in mass application. While waveguide filters provide excellent performance, their physical size and manufacturing cost are prohibitive making it impossible to meet the requirements of a 5G infrastructure.

In recent years, in order to solve the size and cost problems, there is a related research to develop various millimeter wave filters based on the conventional LTCC (Low-temperature co-fired ceramic technology), which have smaller physical size and Low manufacturing cost to solve the disadvantages of on-chip filters and waveguide filters, but such filters often introduce additional interconnection loss and sacrifice larger circuit size for electromagnetic isolation and integration of devices in the process of millimeter wave wireless communication system integration, and in addition, as the frequency band increases, the performance of capacitance and inductance based on the LTCC structure decreases, resulting in an increasing parasitic influence, and the performance of the capacitance and inductance cannot meet the requirement of a 5G millimeter wave wireless communication system.

Therefore, in order to reduce the size of the filter circuit and overcome the defect that the conventional millimeter wave filter based on the LTCC structure cannot be applied at high frequency, a millimeter wave filter based on the stripline resonator design is proposed at present, as shown in fig. 1, (a) in fig. 1 is a schematic diagram of the filter structure, (b) in fig. 1 is a diagram of simulation and test results of insertion loss and return loss, and 5 stripline resonators in (a) are laid flat and arranged in two layers in sequence, and the filter is realized by coupling the upper layer and the lower layer. The bottom layer is a ground plane, and a shielding module is designed above the top layer to isolate electromagnetic interference. Although the filter constructed based on the LTCC structure can realize a miniaturized millimeter wave filter to a certain extent, the insertion loss of the filter is large, and the filter is difficult to ensure the yield under the condition of large-batch processing due to the processing deviation of the traditional LTCC process. In addition, this type of filter requires an additional electromagnetic shielding module to block electromagnetic interference, which would otherwise greatly affect the operating performance of the wireless communication system. Therefore, a small-sized millimeter wave filter with high performance and low cost is needed to meet the requirement of the millimeter wave wireless communication system in the 5G terminal.

Disclosure of Invention

The application provides a filter and a wireless communication system, and provides a miniaturized millimeter wave filter with high performance and low cost, so as to meet the requirement of a millimeter wave wireless communication system in a 5G terminal.

In a first aspect, an embodiment of the present application provides a filter, where the filter includes: the circuit comprises a first metal layer, a first circuit layer, a second circuit layer, a third circuit layer and a second metal layer which are sequentially stacked;

the first circuit layer, the second circuit layer and the third circuit layer respectively comprise a circuit structure area and a side edge packaging area surrounding the circuit structure area, and the circuit structure areas are arranged in parallel and in a laminated mode to form a core circuit area of the filter; the first circuit layer is a feeder layer, the second circuit layer is provided with a grounding resonator, and the third circuit layer is provided with a step impedance resonator;

the first metal layer, the second metal layer and the side edge packaging area form a closed cavity in a surrounding mode, and the core circuit area is arranged in the closed cavity;

the side edge packaging area is also provided with an input port and an output port, and the core circuit area is connected with the input port and the output port.

With reference to the first aspect, in an implementation manner, the side edge package area is provided with a plurality of through holes, the first metal layer, the second metal layer and the side edge package area are connected by inserting metal pillars into the through holes, and the 3-layer circuit structures of the first circuit layer, the second circuit layer and the third circuit layer are connected by the metal pillars.

With reference to the first aspect, in one implementation manner, a feeder shape of the feeder layer, a ground resonator shape, or a stepped impedance resonator shape is a U-shape, an L-shape, a C-shape, or a spiral shape.

With reference to the first aspect, in one implementation manner, the circuit structure of the first circuit layer is a symmetrically arranged U-shaped feeder layer, the circuit structure of the second circuit layer is a one-fourth wavelength grounded resonator, and the circuit structure of the third circuit layer is a one-fourth wavelength stepped impedance resonator.

With reference to the first aspect, in one implementation, the input and output ports are connected to the feeder layer by stripline connections.

With reference to the first aspect, in one implementation manner, the coupling between the circuit structures in the core circuit region includes strong coupling and weak coupling, where the strong coupling includes coupling between circuit structures in adjacent layers in the core circuit region and coupling between through holes of the ground resonator; the weak coupling includes a horizontal coupling of the feeder layer and a coupling between the cross-layer circuit structures of the core circuit area.

With reference to the first aspect, in one implementation manner, the first metal layer and the second metal layer are grounding metals.

With reference to the first aspect, in an implementation manner, the filter has a rectangular three-dimensional structure, and the sealed cavity in which the core circuit region is located is filled and fixed with a medium to fix the circuit structure in the core circuit region.

In a second aspect, an embodiment of the present application provides a wireless communication system, which includes the filter of any one of the first aspect.

With reference to the second aspect, in an implementation manner, the wireless communication system further includes a millimeter wave chip and an antenna, the filter is connected to the millimeter wave chip and the antenna through interconnection lines, and the filter, the millimeter wave chip and the antenna are integrated in the same PCB.

The application discloses filter and wireless communication system, wherein, the filter includes: the circuit comprises a first metal layer, a first circuit layer, a second circuit layer, a third circuit layer and a second metal layer which are sequentially stacked; the first circuit layer, the second circuit layer and the third circuit layer respectively comprise a circuit structure area and a side edge packaging area surrounding the circuit structure area, and the circuit structure areas are arranged in parallel and in a laminated mode to form a core circuit area of the filter; the first circuit layer is a feeder layer, the second circuit layer is provided with a grounding resonator, and the third circuit layer is provided with a step impedance resonator; the first metal layer, the second metal layer and the side edge packaging area form a closed cavity in a surrounding mode, and the core circuit area is arranged in the closed cavity; the side edge packaging area is also provided with an input port and an output port, and the core circuit area is connected with the input port and the output port. Adopt aforementioned structure, not only can effectual isolation electromagnetic radiation's interference through airtight cavity, also can reduce the radiation loss of wave filter, do not need additionally to add shielding module, and the core circuit of wave filter adopts the laminated design structure, the setting combines the inner space of living by the parcel that the side encapsulation region constitutes at top layer and bottom metal, can reduce the volume of wave filter, this structure does not increase the physical dimensions of wave filter, and easily processing and integration, and save the cost, in addition, utilize the strong coupling between the circuit that the stromatolite set up, promote the performance of wave filter.

Drawings

In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a millimeter wave filter designed based on a strip line resonator provided in the prior art;

fig. 2 is an external view of a filter provided in an embodiment of the present application;

FIG. 3 is a perspective view of the overall structure of a filter provided in an embodiment of the present application;

FIG. 4 is a block diagram of a filter partition according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of a circuit structure provided in an embodiment of the present application;

fig. 6 is a schematic diagram of core circuit area connections provided by an embodiment of the present application;

fig. 7 is a planar coupling topology structure diagram of a core circuit area provided in an embodiment of the present application;

fig. 8 is a three-dimensional coupling structure diagram of a core circuit area provided in an embodiment of the present application;

FIG. 9 is a graph of simulation calculation results based on the coupling structure in FIG. 8 according to an embodiment of the present application;

fig. 10 is a schematic structural diagram of a wireless communication system according to an embodiment of the present application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, the present application is described in further detail with reference to the accompanying drawings and the detailed description.

As can be seen from the description of the background art, the insertion loss of the presently proposed millimeter wave filter designed based on the stripline resonator is relatively large, and in order to solve the problem of the insertion loss, the design of applying a SIW (Substrate integrated waveguide) structure to the LTCC millimeter wave structure filter also appears, and this structure can effectively reduce the insertion loss of the filter and has not very strict requirements on the processing precision. However, the size of the SIW structure is relatively large, the cost of the designed filter is higher than that of the traditional structure, and the application range of the designed filter is greatly limited due to the relatively large physical size.

Therefore, in order to solve the above problem, the present application proposes a filter, as shown with reference to fig. 2 to 4, comprising: the circuit board comprises a first metal layer, a first circuit layer, a second circuit layer, a third circuit layer and a second metal layer which are sequentially stacked.

Fig. 2 is an overall structural view of the filter, as shown in fig. 2, the thickness of the circuit layers being 15um and the interval between the circuit layers being 60um as an example, and fig. 3 is a perspective view of the filter, as shown in fig. 3, the filter being shown as an exampleIs 1.5mm³×1.5mm³×0.315mm³。

The first circuit layer, the second circuit layer and the third circuit layer respectively comprise a circuit structure area and a side edge packaging area surrounding the circuit structure area, and the circuit structure areas are arranged in parallel and in a laminated mode to form a core circuit area of the filter; the first circuit layer is a feeder layer, the second circuit layer is provided with a grounding resonator, and the third circuit layer is provided with a step impedance resonator.

The first circuit layer, the second circuit layer and the third circuit layer are also metal layers, and corresponding circuit functions are realized by etching metal patterns. As shown in fig. 5, fig. 5 is an example of the preparation of a circuit structure, and the preparation process includes: and spin-coating photoresist, placing a mask plate, exposing by ultraviolet light, etching, and taking out the mask plate to obtain a required circuit structure.

In this embodiment, a core circuit area of the filter is a three-layer circuit structure that is parallel and stacked, the core circuit area includes the feeder line, the ground resonator, and the step-impedance resonator (SIR), and the first circuit layer, the second circuit layer, and the third circuit layer are connected around the periphery of the side of the circuit structure area to form a side encapsulation area.

The stacking and placing mode of the circuit structures in the embodiment of the application can effectively reduce the core size of the filter, and a wider passband range and lower insertion loss are designed by utilizing a stronger upper-layer and lower-layer coupling relation.

The first metal layer, the second metal layer and the side edge packaging area form a closed cavity in a surrounding mode, and the core circuit area is arranged in the closed cavity.

The space of the core circuit area is a wrapped inner space formed by combining the top layer metal and the bottom layer metal with the side edge packaging area, and the core circuit of the filter is designed in the inner space. The self-packaging cavity structure not only can effectively isolate the interference of electromagnetic radiation, but also can reduce the radiation loss of the filter, therefore, the structure does not increase the physical size of the filter, and is easy to process and integrate.

The side edge packaging area is also provided with an input port and an output port, and the core circuit area is connected with the input port and the output port.

The reserved space of the side edge packaging area is used for placing input and output ports, specifically, the input and output ports are arranged on the first circuit layer, and the design of the input and output ports can be adjusted according to actual needs.

Optionally, the side edge packaging region is provided with a plurality of through holes, the first metal layer, the second metal layer and the side edge packaging region are connected by inserting metal pillars into the through holes, and the 3 layers of circuit structures of the first circuit layer, the second circuit layer and the third circuit layer are connected through the metal pillars.

As shown in fig. 6, (a) in fig. 6 is a schematic connection diagram of a first metal layer, a first circuit layer, a second circuit layer, and a third circuit layer, (b) is a first circuit layer, (c) is a second circuit layer, and (d) is a third circuit layer, wherein the side edge package region mainly achieves a metal-like package effect by close placement of through holes (vias), dense connection of the through holes not only improves the physical structure stability of the filter, reduces electromagnetic radiation outside the filter core circuit, effectively isolates interference of the electromagnetic radiation, reduces radiation loss of the filter, but also forms a housing of the self-package structure, and a plurality of holes arranged at the edges of the first circuit layer, the second circuit layer, and the third circuit layer in fig. 6 are through holes. The circuit structures in the core circuit region are connected by metal columns, that is, the metal columns are inserted into the through holes to realize connection, in fig. 6, through holes are formed in one end of each circuit structure, and the metal columns are connected with the through holes to connect the circuit structures.

According to the technical scheme, the core circuit structure is designed in the sealed space after being packaged, firstly, the radiation loss of the filter can be reduced by the structure, the performance of the filter is improved, secondly, the periphery of the sealed space can serve as a shielding structure, the influence of the external environment on the performance of the filter is basically isolated, the filter is suitable for various harsh use environments, and can be compatible in PCB (printed circuit board) processes with more layers.

Optionally, a feeder shape of the feeder layer, a ground resonator shape, or a stepped impedance resonator shape is a U-shape, an L-shape, a C-shape, or a spiral shape.

The feeder layer comprises a feeder, the shape of the ground resonator or the shape of the step impedance resonator can be set to be a U shape, an L shape, a C shape, a spiral shape, a concave shape or the like, and when different structural shapes are adopted, the structural response is also the same as long as the same coupling size is realized. The coupling change trends and the change ranges among different shapes are different, so that the structure can be set according to actual needs, and the application is not particularly limited.

Optionally, the circuit structure of the first circuit layer is a symmetrically arranged U-shaped feeder layer, the circuit structure of the second circuit layer is a one-fourth wavelength ground resonator, and the circuit structure of the third circuit layer is a one-fourth wavelength stepped impedance resonator.

The feeder line in the feeder line layer is symmetrically arranged in a U shape to save space, the 4-th wavelength grounding resonator is symmetrically arranged in two U shapes, the 2-th wavelength step impedance resonator is similar to a concave shape, and the core circuit structure is arranged in the shape, so that the circuit size can be reduced, the size of the filter is effectively reduced, and the stop band performance of the filter can be effectively improved.

Optionally, the input and output ports are connected to the feeder layer by stripline connections.

The input and output ports of the filter are connected with the feeder layer through a 50-ohm strip line, and the port is very suitable for being integrated with a millimeter wave system, so that the interconnection loss is reduced.

Optionally, the coupling between the circuit structures in the core circuit area comprises strong coupling and weak coupling, and the strong coupling comprises coupling between circuit structures in adjacent layers of the core circuit area and coupling between through holes of the grounded resonator; the weak coupling includes a horizontal coupling of the feeder layer and a coupling between the cross-layer circuit structures of the core circuit area.

As shown in fig. 7-8, fig. 7 (a) is a planar coupling topology structure diagram of a core circuit area of a filter, fig. 7 (b) is an example of circuit structures of respective layers, fig. 8 is a solid coupling structure diagram of circuit structures of a filter, in this example, coupling between circuit structures in the core circuit area, that is, strong coupling between a resonator and a resonator, is mainly achieved by two ways: 1) upper and lower layer coupling, which is mainly electric coupling, as shown by M in the diagram (a) of FIG. 8_S1，M_L3M in FIG. 8 (b)₁₂And M₂₃(ii) a 2) Coupling between vias of grounded resonators, mainly by magnetic coupling, e.g. M in the diagram (c) of FIG. 8₁₃Both coupling modes can realize a very large coupling size adjusting range by adjusting the shape and the position of the filter. The weak coupling is also achieved in two ways: 1) horizontal coupling, M of the diagram (d) in FIG. 8_SL(ii) a 2) Cross-layer coupling, M of the diagram (e) in FIG. 8_S2And M_L2The weak coupling generally functions to form a cross-coupled topology to create a zero near the passband to improve the filter selectivity. The zero position can be adjusted by adjusting the magnitude of the weak coupling to improve the performance of the filter. According to the coupling matrix, the simulation calculation result of the filter is shown in fig. 9, and it can be seen that the calculation result is very close to the simulation result, and the novel cross-coupling topological structure can generate 3 different zeros around the pass band of the filter, and is very suitable for the design of the filter with low loss and high selectivity.

In addition, the strong and weak coupling size of the filter can be adjusted in a larger range, so that the design threshold of the filter is greatly widened, and most application requirements are met.

Therefore, the circuit structure is based on a three-dimensional coupling mode, and combines a cross-coupling topological theory to generate a plurality of transmission zeros around the filter passband, so that the selectivity of the filter is effectively improved.

Optionally, the first metal layer and the second metal layer are ground metals.

And the first metal layer and the second metal layer are both grounding metals according to actual requirements.

Optionally, the filter has a rectangular three-dimensional structure, and the circuit structure in the core circuit region is fixed by filling a sealing cavity in which the core circuit region is located with a medium.

The filter is manufactured based on a high-precision multilayer PCB processing technology, a medium is arranged between a metal layer and a metal layer, the traditional medium comprises ceramics, glass, a plastic plate and the like, and the processing technology is designed and manufactured by adopting a new material with excellent high-frequency performance.

Based on the filter disclosed above, an embodiment of the present application further discloses a wireless communication system, which includes the filter described in any one of the above.

Optionally, as shown in fig. 10, the wireless communication system is a millimeter wave wireless communication system, the millimeter wave wireless communication system further includes a millimeter wave chip and an antenna, the filter is connected to the millimeter wave chip and the antenna through interconnection lines, and the filter, the millimeter wave chip and the antenna may be integrated in the same PCB.

Fig. 10 (a) and (b) show wireless communication systems with two structures, RFIC shows a radio frequency integrated circuit, Shield is a protective layer of the radio frequency integrated circuit, the radio frequency integrated circuit and the protective layer thereof form a millimeter wave chip, the wireless communication system can realize high integration of the millimeter wave chip, a filter and an antenna through an internal interconnection line, which not only greatly reduces interconnection loss among modules in the system, but also greatly reduces circuit area and processing cost because the structures of the antenna, the filter, a power supply module of the chip and the like can be simultaneously designed in the same PCB, and the filter structure therein is designed based on a self-sealing structure, can effectively Shield electromagnetic radiation, does not increase circuit size, and is very suitable for the application of the millimeter wave wireless communication system of a 5G terminal.

In order to make the solution of the present application clearer, the present application further discloses the following specific examples.

Examples

The filter is composed of a first metal layer, a first circuit layer, a second circuit layer, a third circuit layer and a second metal layer from top to bottom in sequence, the first metal layer, the first circuit layer, the second circuit layer, the third circuit layer and the second metal layer are packaged into a cuboid structure, the circuit structure of the first circuit layer adopts a U-shaped feeder line, the circuit structure of the second circuit layer is set to be a one-fourth wavelength grounding resonator, the circuit structure of the third circuit layer is set to be a one-fourth wavelength step impedance resonator, the band-pass filter manufactured by adopting the structure takes 28GHz as central frequency, the 3-dB bandwidth of the band-pass filter is 27.9%, and the band-pass filter is 1.5mm in width³×1.5mm³×0.315mm³A minimum of 1.3dB in-band insertion loss is achieved at the compact size of (a). Because of the adoption of a multi-pole cross coupling structure and the fact that the stop band performance of the SIR resonator is quite outstanding, the suppression level of the lower stop band from DC-22.8GHz is more than 21.3 dB; the upper stop band can be restrained to 110GHz, and the stop band bandwidth can be expanded to 3.92f₀The out-of-band rejection level may be greater than-24 dB.

The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.