A coupling circuit board and radio frequency circuit
By setting a series resistor at the output port of the coupled circuit board, crosstalk from distant signals is absorbed, solving the problem of poor isolation of the coupled circuit board under high-density wiring, and achieving efficient improvement in isolation performance and port testing accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- MOBILE ANTENNA TECH SHENZHEN
- Filing Date
- 2025-05-16
- Publication Date
- 2026-06-05
AI Technical Summary
Under high-density cabling conditions, electromagnetic coupling between adjacent paths on coupled circuit boards is enhanced, leading to increased signal crosstalk and affecting the isolation performance and test accuracy between output ports. Existing technologies struggle to achieve effective isolation without significantly altering the cabling structure.
A series resistor is set at the output port of the coupling circuit board, and a remote microstrip line or stripline is connected through the surface microstrip line. A series resistor is set on each surface microstrip line. The high-frequency impedance characteristics of the resistor are used to absorb crosstalk signals from the remote end and block their propagation to the output port.
It effectively reduces signal crosstalk, improves the isolation performance between output ports and the accuracy of port testing, and is especially suitable for space-constrained applications in high-density RF circuits, significantly improving the electromagnetic compatibility performance of the system.
Smart Images
Figure CN224328895U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of communication technology, and in particular to a coupling circuit board and radio frequency circuit. Background Technology
[0002] Coupling circuit boards (PCBs), as key signal processing components in the radio frequency (RF) and microwave fields, are widely used in typical scenarios such as high-frequency communication systems, phased array radars, satellite communications, and 5G base stations. They are primarily used to achieve functions such as RF signal transmission, directional coupling, power distribution, and port isolation. These PCBs typically use high-frequency wiring structures such as microstrip lines and striplines to directionally extract a portion of the energy from the main transmission path for purposes such as power detection, reflection monitoring, or feedback control.
[0003] As wireless devices become increasingly integrated, the spacing between coupled signal paths is compressed to 0.1mm or even smaller, leading to enhanced electromagnetic coupling and increased crosstalk between adjacent paths. This poses a serious technical problem affecting the isolation performance and testing accuracy between output ports. While isolation solutions in related technologies, such as widening channel spacing, adding grounding wires, and installing metal shielding layers, can reduce crosstalk to some extent, these methods are often difficult to implement practically due to limited board space and cost constraints.
[0004] Therefore, there is an urgent need for an isolation optimization technology solution that is simple in structure, low in cost, and highly adaptable without significantly altering the existing wiring structure, so as to achieve effective isolation control of coupled circuit boards under high-density wiring conditions. Utility Model Content
[0005] The main objective of this invention is to provide a coupling circuit board and radio frequency circuit to at least solve the technical problems in the background art.
[0006] To achieve the above objectives, this utility model provides the following technical solution:
[0007] A first aspect of this utility model is to provide a coupling circuit board, wherein at least two coupling signal paths are provided on the coupling circuit board;
[0008] Each of the aforementioned coupled signal paths is configured with an output port;
[0009] Each of the output ports is connected to a remote microstrip line or stripline via a surface microstrip line, the remote microstrip line or stripline being used for electrical connection to a coupled signal port;
[0010] In this embodiment, a series resistor is provided on each of the surface microstrip lines, and the series resistor is located between the output port and the remote microstrip line or the stripline.
[0011] Based on the first aspect, in each coupling path, each of the series resistors is closer to the output port relative to the distal microstrip line or stripline;
[0012] The multiple series resistors are used to reduce the impact of signal crosstalk from the remote microstrip line or stripline on the isolation between the output ports and to optimize the isolation performance between the output ports.
[0013] Based on the first aspect, the series resistor is a resistive device, which is connected in series on the surface microstrip line and located between the output port and the remote microstrip line or the stripline.
[0014] Based on the first aspect, the resistive device is a surface mount resistor mounted on the surface microstrip line.
[0015] Based on the first aspect, the resistor is fixed to the surface microstrip line by welding, and its fixed position is located in the region close to the output port to suppress the crosstalk effect of the far-end signal on the output port.
[0016] Based on the first aspect, the distances between the two series resistors in the two adjacent coupled signal paths and the corresponding output ports are equal.
[0017] Based on the first aspect, the resistance value of the series resistor is negatively correlated with the length of the crosstalk path;
[0018] The length of the crosstalk path is the distance between the remote microstrip line or stripline and the output port.
[0019] Based on the first aspect, the inner layer of the coupling circuit board is provided with a stripline structure for signal transmission;
[0020] The crosstalk path formed by the stripline is located on the side of the resistor device away from the output port.
[0021] Based on the first aspect, the resistance value of the series resistor is between 20Ω and 200Ω.
[0022] A second aspect of this utility model provides a radio frequency circuit, including a circuit body and a coupling circuit board as described in the first aspect.
[0023] This invention discloses a coupling circuit board and RF circuit. The coupling circuit board has at least two coupled signal paths, each corresponding to an output port. Each output port is connected to a remote microstrip line or stripline via a surface microstrip line. A series resistor is installed on each surface microstrip line between the output port and the remote microstrip line or stripline. Therefore, this technical solution utilizes the high-frequency impedance characteristics of the resistor on the surface microstrip line at the output port of the coupling circuit board to absorb crosstalk signals from the remote coupling path, effectively blocking the propagation path of signal interference to the output port, thereby improving the isolation performance between output ports. Furthermore, this solution does not require significant modification to the original wiring structure of the circuit board, is simple in structure, and low in cost. It is particularly suitable for high-density RF circuits in space-constrained environments with high isolation requirements, and can significantly improve the accuracy of port testing and the electromagnetic compatibility performance of the system. Attached Figure Description
[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0025] Figure 1 This is a partial structural schematic diagram of the coupling circuit board provided in an embodiment of this application;
[0026] Figure 2 This is a schematic diagram of the structure of the coupling circuit board provided in the embodiments of this application;
[0027] Reference numerals: Coupled circuit board 1; Output ports 2, 3; Surface microstrip lines 4, 5; Series resistors 6, 7; Remote microstrip lines 8, 9; Coupled signal ports 10, 11. Detailed Implementation
[0028] 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 a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0029] It should be noted that related terms such as "first" and "second" can be used to describe various components, but these terms do not limit the component. These terms are only used to distinguish one component from another. For example, without departing from the scope of this utility model, the first component can be referred to as the second component, and the second component can similarly be referred to as the first component. The term "and / or" refers to any one or more combinations of related and descriptive terms.
[0030] Please see Figure 1 and Figure 2 This application provides a coupling circuit board 1, which has at least two coupling signal paths.
[0031] This application illustrates the embodiments using two coupled signal paths:
[0032] The two coupled signal paths are used to transmit independent high-frequency radio frequency signals, forming two adjacent coupled channels in the circuit board.
[0033] Each coupled signal path is assigned an output port (an output port is the electrical signal output connection point at the end of each coupled signal path), such as output port 2 and output port 3, which are located at the edge of the coupled circuit board 1 or in the test area, and are used to connect to test equipment or lower-level modules.
[0034] After each output port, there is a surface microstrip line for signal transmission, namely microstrip line 4 and microstrip line 5. The surface microstrip line connects the output port to the remote microstrip line 8 and microstrip line 9 (or stripline). That is, each output port (2, 3) is connected to a remote microstrip line (8, 9) or stripline through a surface microstrip line (4, 5). The remote microstrip line (8, 9) or stripline is used to electrically connect to the coupling signal port (10, 11, generally referring to the input port on each signal path of the coupling circuit board used to access the external radio frequency signal source).
[0035] Each surface microstrip line (4, 5) is provided with a series resistor, such as series resistor 6 and series resistor 7, which are located between the output port (2, 3) and the remote microstrip line (8, 9) or stripline. This can suppress the influence of electromagnetic crosstalk between the remote coupling paths on the isolation between the output ports.
[0036] It should be understood that different coupled circuit boards 1 may form remote microstrip lines (8, 9) or striplines depending on the specific wiring method, and both may participate in the formation of crosstalk paths. Remote microstrip lines are more sensitive to high-frequency coupling, while striplines are suitable for high-isolation layouts on multilayer boards. The series resistor design in this embodiment can be adapted to the above-mentioned different types of trace structures, and targeted interference suppression can be achieved by adjusting the structural position and resistance value.
[0037] As can be seen, this embodiment of the application sets series resistors (6, 7) on the surface microstrip lines (4, 5) at the output ports (2, 3) of the coupling circuit board 1, ensuring that the coupled signals in the coupled signal path must pass through these series resistors (6, 7) before entering the output ports (2, 3). Since resistors have significant energy dissipation characteristics under high-frequency conditions, they can effectively absorb and attenuate high-frequency crosstalk components in the propagation path, thereby reducing the degree of mutual interference between coupled signals. In short, it can effectively reduce signal crosstalk between the far-end microstrip line 8 (or stripline) and the far-end microstrip line 9 caused by spacing and space limitations, thereby improving isolation function (optimizing isolation).
[0038] In addition, the embodiments of this application do not require significant modifications to the original wiring structure of the circuit board. The structure is simple and the cost is low. It is particularly suitable for high-density radio frequency circuits with limited space and high isolation requirements, and can significantly improve the accuracy of port testing and the electromagnetic compatibility performance of the system.
[0039] The following is a distinguishing description of the surface microstrip lines (4, 5) and the distal microstrip lines (8, 9) in the embodiments of this application:
[0040] Firstly: The surface microstrip lines (4, 5) are set on the surface conductive layer of the circuit board, located between the output ports (2, 3) and the remote microstrip lines (8, 9); while the remote microstrip lines (8, 9) can be set on the same layer or the inner layer, usually as the signal extension part led out from the main coupling path, connected to the coupling signal source or other processing circuits.
[0041] Secondly, the surface microstrip lines (4, 5) serve as the direct connection between the output signal and the external circuit or test equipment. Their electrical characteristics have a significant impact on port isolation and signal integrity. Meanwhile, the far-end microstrip lines (8, 9) are extensions of the signal path and are potential sources of crosstalk. Their position and orientation determine the strength and direction of the crosstalk coupling path.
[0042] Thirdly: Series resistors (6, 7) are set in the surface microstrip lines (4, 5), specifically between the output port and the remote microstrip lines (8, 9); while the remote microstrip lines themselves do not have resistors, their main function is to simulate remote signal interference sources and to verify the crosstalk absorption and isolation improvement effect.
[0043] In an optional embodiment of this application, in each coupling path, each series resistor (6, 7) is located close to the output port (2, 3) relative to the distal microstrip line (8, 9) or stripline. The multiple series resistors are used to reduce the impact of signal crosstalk from the distal microstrip line or stripline on the isolation between the output ports and to optimize the isolation performance between the output ports.
[0044] Specifically, a resistor is installed in each of the surface microstrip lines 4 and 5. The resistor is preferably placed closer to the output port, that is, between the output port and the far-end microstrip line, closer to the output port, thereby forming a "pre-absorption" structure for crosstalk energy in the signal path.
[0045] It should be noted that signal crosstalk mainly originates from the coupling between the far-end microstrip lines 8 and 9. If not suppressed, this crosstalk signal can feed back along the microstrip line to the output port, affecting its isolation performance. In this embodiment, by placing series resistors (6 and 7) at the front end of the output port, electromagnetic coupling easily occurs between the far-end paths when multiple coupled signal paths are arranged in parallel under high-density wiring conditions, generating crosstalk signals. These interference signals propagate in the reverse direction along the microstrip line to the output port, thus reducing the isolation performance between adjacent ports and affecting test accuracy and system stability. The high-frequency impedance characteristics of the series resistors (6 and 7) can absorb the crosstalk signals from the far-end coupled paths (reducing their strength transmitted to the output port), effectively blocking the propagation path of signal interference to the output port, thereby improving the isolation performance between the output ports (2 and 3).
[0046] In an optional embodiment of this application, the series resistor can be a resistor device, which is disposed in series on the surface microstrip line and located between the output port and the remote microstrip line or stripline.
[0047] Specifically, to suppress crosstalk signals from the remote path and improve the isolation performance between output ports, a partial break can be made in the middle of each surface microstrip line, and pads can be placed on both sides of the break point for mounting resistors. The two ends of the resistors are soldered to the pads on both sides of the microstrip line break point by reflow soldering or other methods, forming a complete electrical series connection.
[0048] In an optional embodiment of this application, the resistor is a surface mount resistor mounted on the surface microstrip line.
[0049] Specifically, the surface-mount resistor is positioned in the middle section of the surface microstrip line between the output port and the remote microstrip line. The mounting method can be as follows: a break is designed in the middle of the pre-defined microstrip line, with standard surface-mount pads reserved on both sides of the break. The resistor is then soldered in series into the microstrip line structure using surface mount technology (SMT). A continuous electrical connection is formed between the resistor and the microstrip line, ensuring that the signal must pass through this resistor during transmission from the output port to the remote microstrip line.
[0050] In an optional embodiment of this application, the resistor is fixed to the surface microstrip line by welding, and its fixed position is located in the region close to the output port, so as to suppress the crosstalk effect of the far-end signal on the output port.
[0051] Specifically, a solder break area is pre-defined in the surface microstrip line. Surface mount resistors are soldered onto pads on both sides of this break using standard surface mount soldering technology, embedding them in a series structure within the signal transmission path. Simultaneously, to achieve optimal isolation, the resistors are preferably mounted closer to the output port (e.g., the distance between this region and the output port can be 300μm to 1500μm), allowing them to undergo high-frequency energy attenuation via the resistor path before the coupled signal from the far end is fed back to the output port. This structural arrangement effectively blocks crosstalk signals generated by the far-end microstrip line or stripline from being transmitted to the output port, thereby optimizing the isolation performance between multiple output ports.
[0052] In an optional embodiment of this application, the distances between the two series resistors in two adjacent coupled signal paths and their corresponding output ports are equal.
[0053] Specifically, the coupling circuit board has a first coupling signal path and a second coupling signal path. Each path is connected to a distant microstrip line or stripline via a surface microstrip line. A series resistor is placed in the middle of each microstrip line. In this embodiment, the distance between the series resistor 6 and the output port 2 is equal to the distance between the series resistor 7 and the output port 3. This equidistant arrangement helps to ensure the symmetry of the two signal channels in terms of electromagnetic structure and impedance characteristics, so that the crosstalk path length, the resistance application point, and the high-frequency energy attenuation effect remain consistent in the two channels. This improves the consistency of the isolation performance between channels and the overall controllability of the system, and is especially suitable for RF systems with extremely high channel matching requirements, such as radar beamformers.
[0054] In an optional embodiment of this application, the resistance value of the series resistor is negatively correlated with the length of the crosstalk path; wherein, the length of the crosstalk path is the distance between the remote microstrip line or stripline and the output port.
[0055] Specifically, based on the electromagnetic characteristics of crosstalk propagation, when the crosstalk path is long, the signal energy has already attenuated to some extent during propagation, and the required series resistance value can be appropriately reduced. Conversely, when the path is short and the interference coupling is stronger, a resistor with a larger resistance value should be selected to enhance high-frequency absorption capability. This implementation method, by defining the correlation between the resistance value and the length of the crosstalk path, allows for the independent selection of matching resistance parameters in each coupling path to achieve targeted crosstalk suppression and improve the isolation between output ports.
[0056] It should also be noted that the resistance value of the series resistor in this embodiment can be adjusted according to the system frequency and actual isolation requirements, typically ranging from 20Ω to 200Ω, to effectively absorb crosstalk from distant signals while maintaining the quality of the main signal transmission as much as possible. The resistor is preferably mounted close to the output port area to maximize the blocking of feedback paths of coupled interference signals at the end of the signal chain. Furthermore, in most RF and microwave applications, such as 5G RF front-ends, power detection modules, and phased array RF daughterboards, the resistance value can be further limited to between 33Ω and 100Ω to achieve a good balance between versatility, suppression effect, and signal integrity.
[0057] In an optional embodiment of this application, the inner layer of the coupling circuit board is provided with a stripline structure for signal transmission, and the crosstalk path formed by the stripline is located on the side of the resistor device away from the output port.
[0058] Specifically, when setting up the resistor device, its position can be set before the crosstalk path formed by the inner stripline, that is, in the shielding position between the output port and the stripline. With this structural setting, when electromagnetic crosstalk in the far-end signal path couples to the output port through the stripline, it must pass through the series resistor path, thereby generating significant high-frequency energy attenuation during propagation, achieving the technical effect of shielding and absorbing crosstalk interference.
[0059] This application also provides a radio frequency circuit, including a circuit body and a coupling circuit board as described in the above embodiments.
[0060] The coupling circuit board and RF circuit of this application embodiment have at least two coupling signal paths on the coupling circuit board, each coupling signal path corresponding to an output port. Each output port is connected to a remote microstrip line or stripline via a surface microstrip line. A series resistor is set on each surface microstrip line, located between the output port and the remote microstrip line or stripline. It can be seen that this technical solution, by setting a series resistor on the surface microstrip line at the output port of the coupling circuit board, utilizes the high-frequency impedance characteristics of the resistor to absorb crosstalk signals from the remote coupling path, effectively blocking the propagation path of signal interference to the output port, thereby improving the isolation performance between output ports. Furthermore, this solution does not require significant modification to the original wiring structure of the circuit board, is simple in structure and low in cost, and is particularly suitable for space-constrained and high-isolation-requirement applications in high-density RF circuits, significantly improving the accuracy of port testing and the electromagnetic compatibility performance of the system.
[0061] In summary, existing technologies that rely on increasing spacing, adding grounding wires, or shielding layers are difficult to implement due to space and cost constraints. However, the embodiments in this application offer a cost-effective and efficient isolation optimization solution that does not require significant modifications to existing wiring.
[0062] This application embodiment effectively absorbs crosstalk noise and blocks crosstalk paths in inner striplines by adding resistors at key nodes in the high-frequency signal path, thereby improving the isolation performance between different coupled lines. In the field of communications, it is particularly suitable for optimizing and improving the isolation performance of output port tests on coupled circuit boards in the RF and microwave fields, thus solving the technical problem of poor output port isolation caused by dense wiring and space constraints.
[0063] The specific embodiments of the utility model have been described in detail above, but they are only examples, and the utility model is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications or substitutions to the utility model are also within the scope of the utility model. Therefore, all equivalent transformations, modifications, and improvements made without departing from the spirit and principles of the utility model should be covered within the scope of the utility model.
Claims
1. A coupling circuit board, characterized in that, The coupling circuit board is provided with at least two coupling signal paths; Each of the aforementioned coupled signal paths is configured with an output port; Each of the output ports is connected to a remote microstrip line or stripline via a surface microstrip line, the remote microstrip line or stripline being used for electrical connection to a coupled signal port; In this embodiment, a series resistor is provided on each of the surface microstrip lines, and the series resistor is located between the output port and the remote microstrip line or the stripline.
2. The coupling circuit board as described in claim 1, characterized in that, In each coupling path, each of the series resistors is located closer to the output port relative to the distal microstrip line or stripline; The multiple series resistors are used to reduce the impact of signal crosstalk from the remote microstrip line or stripline on the isolation between the output ports and to optimize the isolation performance between the output ports.
3. The coupling circuit board as described in claim 2, characterized in that, The series resistor is a resistor device, which is connected in series on the surface microstrip line and located between the output port and the remote microstrip line or the stripline.
4. The coupling circuit board as described in claim 3, characterized in that, The resistor is a surface mount resistor that is mounted on the surface microstrip line.
5. The coupling circuit board as described in claim 4, characterized in that, The resistor is fixed to the surface microstrip line by welding, and its fixed position is located in the region close to the output port to suppress the crosstalk effect of the far-end signal on the output port.
6. The coupling circuit board as described in claim 2, characterized in that, The distances between the two series resistors in two adjacent coupled signal paths and their corresponding output ports are equal.
7. The coupling circuit board as described in claim 2, characterized in that, The resistance value of the series resistor is negatively correlated with the length of the crosstalk path; The length of the crosstalk path is the distance between the remote microstrip line or stripline and the output port.
8. The coupling circuit board as described in claim 3, characterized in that, The inner layer of the coupling circuit board is provided with a stripline structure for signal transmission. The crosstalk path formed by the stripline is located on the side of the resistor device away from the output port.
9. The coupling circuit board as described in claim 2, characterized in that, The resistance value of the series resistor is between 20Ω and 200Ω.
10. A radio frequency circuit, characterized in that, It includes the circuit body and the coupling circuit board as described in any one of claims 1 to 9.