System and method for suppressing radio frequency interference

Abstract

The embodiment of the invention provides a system and method for suppressing radio frequency interference, and belongs to the field of wireless communication, and the system comprises a circuit board and a metal plane structure which are oppositely arranged; at least two grounding points are arranged on the metal plane structure, the resonant frequency of the metal plane structure can be changed by changing the actual grounding state of the grounding points so as to suppress radio frequency interference, and the radio frequency interference is caused by the fact that a radiation source on the circuit board generates a radio frequency interference signal and is coupled to the metal plane structure. The radio frequency interference suppression of the electronic equipment can be realized, and meanwhile, the effects of low cost, high adaptability and no influence on the original functions of the equipment can be achieved.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication, and particularly relates to a system and method for suppressing radio frequency interference. Background Technology

[0002] In electronic devices such as routers and gateways, various traces and circuit components on the printed circuit board (PCB) generate radio frequency interference signals. These signals can easily be transmitted to the device's metal planar structure through electromagnetic coupling, such as heat sinks, PCB metal areas, and the casing. Because metal planar structures easily form resonant cavities, they amplify and radiate the interference signals outward, causing interference to the device's operating frequency and resulting in problems such as reduced signal transmission rates and communication interruptions.

[0003] There are currently three main core technical solutions for suppressing this type of interference: First, adding radio frequency shielding devices to isolate the radiation source from the metal planar structure through a metal cover. However, this significantly increases the size and weight of the device and may also obstruct heat dissipation channels, preventing the chip from dissipating heat. Second, adding absorbing materials. However, absorbing materials require the addition of a certain proportion of magnetic or precious metal materials, making them several times more expensive than ordinary materials. Moreover, within the limited space of the device, their absorption capacity for low-frequency interference is far worse than that for high-frequency interference, limiting both adaptability and cost-effectiveness. Third, using multilayer PCB technology. Because interfering and interfered circuits need to be placed in different layers to isolate the interference, the design and manufacturing costs of multilayer PCBs increase significantly. Furthermore, this method cannot cover surface-mount interfering devices, which will still radiate some signals, making it impossible to completely solve the interference problem. Therefore, there is an urgent need for a low-cost, highly adaptable radio frequency interference suppression solution that does not affect the original function of the device. Summary of the Invention

[0004] This invention provides a system and method for suppressing radio frequency interference, which can suppress radio frequency interference in electronic devices while achieving low cost, strong adaptability and no impact on the original functions of the devices.

[0005] In a first aspect, embodiments of the present invention provide a system for suppressing radio frequency interference, the system comprising a circuit board and a metal planar structure disposed opposite to each other; The metal planar structure has at least two grounding points. Changing the actual grounding state of the grounding points can change the resonant frequency of the metal planar structure to suppress radio frequency interference. Radio frequency interference is caused by the radio frequency interference signal generated by the radiation source on the circuit board and coupled to the metal planar structure.

[0006] In some embodiments of the present invention, a portion of at least two grounding points are connected to the ground terminal of the circuit board, and the other portion of the grounding points are connected to the ground terminal of the circuit board through a control component.

[0007] In some embodiments of the present invention, the control component is used to control another portion of the grounding points to be grounded or to stop grounding, thereby changing the actual number of grounding points in the metal planar structure.

[0008] In some embodiments of the present invention, the control component is used to switch on and off by receiving a level control signal. When a low level control signal is received, the control component is turned off, a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points are stopped from being grounded. When a high level control signal is received, the control component is turned on, and all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

[0009] In some embodiments of the present invention, when the first operating frequency band of the electronic device is a low frequency band, a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board by a control component, while the other portion of the grounding points are de-grounded; when the first operating frequency band of the electronic device is a high frequency band, all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board by a control component.

[0010] In some embodiments of the present invention, the number of grounding points on the metal planar structure is four, two of which are reference grounding points and the other two are adjustment grounding points. The two reference grounding points are connected to the grounding terminal of the circuit board, and the two adjustment grounding points are connected to the grounding terminal of the circuit board through a control component.

[0011] In some embodiments of the present invention, two reference grounding points are disposed on the first side of the metal planar structure, and the distance between the two reference grounding points is half the wavelength of the radio frequency interference signal; two adjustment grounding points are disposed on the second side of the metal planar structure, and the distance between the two adjustment grounding points is half the wavelength of the radio frequency interference signal; the first side and the second side are arranged opposite to each other.

[0012] In some embodiments of the present invention, the distance between the center of each grounding point and the corresponding side edge does not exceed 1 / 10 of half the wavelength of the radio frequency interference signal.

[0013] In some embodiments of the present invention, the metal planar structure is at least one of the following: a heat sink for an electronic device, a metal region on a circuit board, or a housing for an electronic device.

[0014] In some embodiments of the present invention, at least one via is further provided on the metal planar structure, and the via is located on the resonant path corresponding to half the wavelength of the radio frequency interference signal on the metal planar structure.

[0015] In some embodiments of the present invention, the number of vias is positively correlated with the area of ​​the metal planar structure. When the area of ​​the metal planar structure increases by a rectangular region with half the wavelength of the radio frequency interference signal as the long side, the number of vias increases by at least one.

[0016] Secondly, embodiments of the present invention provide a method for suppressing radio frequency interference, applied to a system for suppressing radio frequency interference. The system includes a circuit board and a metal planar structure disposed opposite to each other; at least two grounding points are provided on the metal planar structure, a portion of the at least two grounding points are connected to the ground terminal of the circuit board, and the other portion of the grounding points are connected to the ground terminal of the circuit board through a control component. The method includes: The main control chip outputs a low-level control signal to cut off the control components. One part of the grounding point of the metal planar structure is connected to the grounding terminal of the circuit board, while the other part of the grounding point is no longer grounded. The main control chip outputs a high-level control signal to turn on the control components, and all grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

[0017] In some embodiments of the present invention, before the main control chip outputs a low-level control signal to cut off the control components, and before a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points are no longer grounded, the method further includes: Real-time acquisition and identification of the primary operating frequency band of electronic devices; The main control chip outputs a low-level control signal, which cuts off the control components. A portion of the grounding points on the metal planar structure is connected to the grounding terminal of the circuit board, while another portion of the grounding points is de-grounded, including: When the first operating frequency band is low, the main control chip outputs a low-level control signal to cut off the control components. Part of the grounding point of the metal planar structure is connected to the grounding terminal of the circuit board, while the other part of the grounding point is no longer grounded. The main control chip outputs a high-level control signal to turn on the control components, connecting all grounding points of the metal planar structure to the grounding terminal of the circuit board, including: When the first operating frequency band is a high-frequency band, the main control chip outputs a high-level control signal to turn on the control components, and all grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

[0018] The system and method for suppressing radio frequency interference provided in this invention involve setting up a circuit board and a metal planar structure, and configuring at least two grounding points on the metal planar structure. By changing the actual grounding state of the grounding points, the resonant frequency of the metal planar structure can be flexibly adjusted, thereby specifically suppressing radio frequency interference generated by radiation sources on the circuit board and coupled to the metal planar structure. Compared with existing solutions that rely on radio frequency shielding devices, absorbing materials, or multilayer PCB technology, this method not only eliminates the need for any additional devices or high-order structures, but also significantly reduces product manufacturing costs by optimizing existing material forms. It also maintains the original spatial layout of the product, avoids additional space occupation, and is compatible with various wireless communication products with high space constraints, such as gateways and routers. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a system for suppressing radio frequency interference provided in an embodiment of the present invention; Figure 2 A schematic diagram of a single microstrip patch antenna; Figure 3 A schematic diagram showing the direction of the radiated electric field corresponding to a single microstrip patch antenna; Figure 4 This is a schematic diagram of two microstrip patch antennas; Figure 5 This is a schematic diagram showing the radiated electric field directions corresponding to two microstrip patch antennas; Figure 6 This is a schematic diagram of the first state of a planar metal structure. Figure 7 This is a schematic diagram of the second state of a planar metal structure. Figure 8 This is a schematic diagram of the simulated gain curve; Figure 9 This is a flowchart illustrating a method for suppressing radio frequency interference provided in an embodiment of the present invention. Detailed Implementation

[0021] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely intended to explain the present invention and not to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the invention.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0023] In electronic devices such as routers and gateways, various traces and circuit components on the printed circuit board (PCB) generate radio frequency interference signals. These signals can easily be transmitted to the device's metal planar structure through electromagnetic coupling, such as heat sinks, PCB metal areas, and the casing. Because metal planar structures easily form resonant cavities, they amplify and radiate the interference signals outward, causing interference to the device's operating frequency and resulting in problems such as reduced signal transmission rates and communication interruptions.

[0024] There are three main core technical solutions for suppressing this type of interference: 1. Add radio frequency shielding devices: Radio frequency shielding devices block the propagation of electromagnetic waves through multiple physical mechanisms.

[0025] 1) Reflection loss: Due to impedance mismatch, when electromagnetic waves enter a highly conductive metal (such as copper or aluminum) from air (with a wave impedance of approximately 377Ω), a strong reflection occurs due to the sudden change in impedance. Free electrons on the metal surface form a reverse current under the action of an alternating electric field, generating an electromagnetic field that is out of phase with the original signal, thus canceling out the energy of the incident wave.

[0026] 2) Absorption Loss: Due to the skin effect, when a radio frequency signal penetrates a metal, eddy currents accumulate on the surface. Electromagnetic wave energy is converted into Joule heat, and the intensity decays exponentially (formula: A=8.68t / δ, where t is the thickness and δ is the skin depth). Copper has a skin depth of approximately 2.1μm at 1GHz, and a 0.5mm thick copper shield will result in an absorption loss exceeding 200dB.

[0027] 3) Multiple reflection loss: In thin-layer shielding, when the thickness of the shielding body approaches the skin depth, internal multiple reflections will reduce the overall shielding effectiveness (SE). This effect is significant in plastic electroplated layers or thin metal foils and needs to be suppressed by increasing the thickness or surface coating.

[0028] However, the disadvantages of adding radio frequency shielding devices are as follows: 1) High cost: Since most products have heat dissipation requirements, shielding covers are generally two-piece designs for easy installation and maintenance, which doubles the price. 2) Large space occupation: Since interference devices and circuits generally occupy a large PCB size and have certain requirements on the internal height of the shielding cover, the shielding device is large in size and occupies most of the product area.

[0029] 2. Adding absorbing materials: Radio frequency signal absorption is achieved by converting the energy of incident electromagnetic waves into heat energy or other forms of energy. The core loss mechanism is as follows.

[0030] 1) Dielectric loss: Polar molecules in microwave absorbing materials (such as carbonyl iron and polyurethane) repeatedly turn under the action of an alternating electric field, generating heat through molecular friction. The larger the loss factor (tanδ=ε'' / ε'), the higher the heat generation efficiency, and the greater the corresponding loss. Carbon nanotubes, graphene, etc. form a conductive network, and the electromagnetic field induces microcurrents to generate Joule heating.

[0031] 2) Magnetic loss: The magnetic domains of ferrite and magnetic alloy continuously flip in an alternating magnetic field, consuming energy. The high-frequency magnetic field induces eddy currents inside the material, which are converted into heat through resistance. Ferrite undergoes magnetic moment precession resonance in the GHz band, which can significantly improve absorption capacity.

[0032] However, the disadvantages of adding absorbing materials are as follows: 1) High cost: Because a certain proportion of magnetic materials or precious metals need to be added to the microwave absorbing material, its cost is several times that of ordinary materials; 2) Limited absorption performance: Since the absorption performance of absorbing materials is closely related to frequency and size, under the same magnetic material density, the lower the frequency, the thicker the material needs to be. Under the condition of fixed size and space, the ability to absorb low-frequency signals is worse than that of high-frequency signals.

[0033] 3. Employ multilayer PCB technology: Multilayer board technology significantly reduces radio frequency interference (RFI) through precise layer stacking structure design and layout routing methods. Its core mechanism and key implementation points are as follows.

[0034] 1) Optimized stacked structure: Adjacent power layers and ground layers form a natural distributed capacitance (0.1~10nF / cm²), providing a low-impedance return path for high-frequency noise and suppressing power ripple; high-speed signals are sandwiched between two ground layers (such as Top-Gnd-Sig-Pwr-Bottom), utilizing the upper and lower ground planes to shield radiation, which reduces radiation by 10~20dB compared to microstrip radiation; cross-segment avoidance is strictly prohibited, and signals are strictly prohibited from crossing the power plane split seam to prevent common-mode noise caused by abrupt changes in the return path.

[0035] 2) Layout and wiring optimization: Use dense via arrays to connect the ground planes of each layer, with via spacing <λ / 20 (e.g., <15mm at 1GHz) to reduce ground impedance (<5mΩ); connect digital ground and analog ground at a single point to avoid low-frequency ground loops, and achieve high-frequency multi-point grounding through parallel capacitors; isolate sensitive areas (such as RF modules) with ground gaps and bridge them with ferrite beads (100MHz@100Ω) or 0Ω resistors to block interference conduction.

[0036] However, the disadvantages of using multilayer PCB technology are as follows: 1) High cost: Because the interfering and interfered lines need to be placed in different layers, at least 4 layers of PCB stack-up structure are required. For every 2 additional layers, the cost of the board material increases by 40% to 60%. The addition of advanced lamination process doubles the total cost. 2) Limited interference handling: Since adding layers only places the traces of interference signals in the middle layer, some surface-mount interference devices will still radiate some signals, causing interference problems.

[0037] Therefore, there is an urgent need for a low-cost, highly adaptable radio frequency interference suppression solution that does not affect the original functions of the equipment.

[0038] To address the aforementioned technical problems, embodiments of the present invention provide a system and method for suppressing radio frequency interference, which can suppress radio frequency interference in electronic devices while achieving low cost, strong adaptability, and no impact on the original functions of the devices.

[0039] Firstly, we will introduce a system for suppressing radio frequency interference provided by an embodiment of the present invention.

[0040] Figure 1 This is a schematic diagram of the structure of a system for suppressing radio frequency interference provided in an embodiment of the present invention; like Figure 1As shown, the system for suppressing radio frequency interference includes a circuit board 110 and a metal planar structure 120 arranged opposite to each other; At least two grounding points 130 are provided on the metal planar structure 120. Changing the actual grounding state of the grounding point 130 can change the resonant frequency of the metal planar structure 120 to suppress radio frequency interference. The radio frequency interference is caused by the radio frequency interference signal generated by the radiation source 140 on the circuit board 110 and coupled to the metal planar structure 120.

[0041] Among them, the core area of ​​radiation source 140 corresponds to the circuit board directly below the grounding point enclosure area on the metal planar structure 120 (i.e., the position of the circuit board directly facing the enclosure area). The radiation source directly below the grounding point enclosure area is the "main interference contributor". The interference signal coupled to the metal plane by radiation sources in other areas is relatively weak.

[0042] The system for suppressing radio frequency interference provided in this invention sets up a circuit board and a metal planar structure, and configures at least two grounding points on the metal planar structure. By changing the actual grounding state of the grounding points, the resonant frequency of the metal planar structure can be flexibly adjusted, thereby specifically suppressing radio frequency interference generated by radiation sources on the circuit board and coupled to the metal planar structure. Compared with the solutions in the prior art that rely on radio frequency shielding devices, absorbing materials or multilayer PCB technology, this system not only eliminates the need for any additional devices or high-order structures, but also significantly reduces product manufacturing costs by optimizing the existing material form. It can also maintain the original spatial layout of the product, avoid additional space occupation, and is compatible with various wireless communication products with high space constraints, such as gateways and routers.

[0043] In some embodiments of the present invention, a portion of at least two grounding points are connected to the ground terminal of the circuit board, and the other portion of the grounding points are connected to the ground terminal of the circuit board through a control component.

[0044] The control component can be a switching diode, such as... Figure 1 As shown, the control component 150, i.e. the first end (anode) of the switching diode, can be connected to the grounding point, and the second end (cathode) of the switching diode can be connected to the grounding point of the circuit board 110. The main control chip 160 is also connected to the first end (anode) of the switching diode. The main control chip 160 controls whether the grounding point is grounded by controlling the switching diode to conduct or cut off.

[0045] Figure 7 This is a schematic diagram of the second state of the metal planar structure. When the switching diode is off, the two reference ground points 711 are grounded, and the other two adjustment ground points 712 are not grounded. When the switching diode is on, the two reference ground points 711 are grounded, and the two adjustment ground points 712 are also grounded.

[0046] The core of the classification connection design with at least two grounding points is to achieve dynamic adjustment of the resonant frequency of the metal plane through the combination of "fixed grounding + controllable grounding": one part of the grounding points are directly connected to the grounding terminal of the circuit board to form a basic grounding architecture, and the other part of the grounding points are connected to the grounding terminal of the circuit board through a control component. By switching the on or off state of the control component, for example, by controlling the high or low level output of the MCU_IO, the total number of actual grounding points of the metal plane can be changed, thereby disrupting or adjusting the resonant conditions of the metal plane, and finally suppressing the radio frequency interference generated by the radiation source on the circuit board coupled to the metal plane structure.

[0047] In some embodiments of the present invention, the control component is used to control another portion of the grounding points to be grounded or to stop grounding, thereby changing the actual number of grounding points in the metal planar structure.

[0048] In some embodiments of the present invention, the control component is used to switch on and off by receiving a level control signal. When a low level control signal is received, the control component is turned off, a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points are stopped from being grounded. When a high level control signal is received, the control component is turned on, and all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

[0049] In some embodiments of the present invention, when the first operating frequency band of the electronic device is a low frequency band, a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board by a control component, while the other portion of the grounding points are de-grounded; when the first operating frequency band of the electronic device is a high frequency band, all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board by a control component.

[0050] In some embodiments of the present invention, the control component is used to switch on and off in response to a level control signal output by the main control chip on the circuit board. When the main control chip outputs a low-level control signal, the control component is turned off, a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points are no longer grounded. When the main control chip outputs a high-level control signal, the control component is turned on, and all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

[0051] In some embodiments of the present invention, when the first operating frequency band of the electronic device is a low frequency band, the main control chip outputs a low-level control signal to turn off the control component, and a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, while the other portion of the grounding points are no longer grounded; when the first operating frequency band of the electronic device is a high frequency band, the main control chip outputs a high-level control signal to turn on the control component, and all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

[0052] In this embodiment of the invention, the control component can achieve precise on / off switching in response to the level control signal output by the main control chip on the circuit board. When the main control chip outputs a low-level control signal, the control component is turned off, so that only a portion of the grounding points of the metal planar structure remain connected to the grounding terminal of the circuit board, while the other portion of the grounding points are no longer grounded. When the main control chip outputs a high-level control signal, the control component is turned on, so that all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board. This design eliminates the need for additional costly RF shielding devices, absorbing materials containing magnetic or precious metal components, and high-level multilayer PCB structures with complex processes and doubled costs. This technology effectively avoids the shortcomings of existing technologies, such as the large space occupied by shielding devices, the limited absorption performance of absorbing materials in the low-frequency band, and the inability of multi-layer PCBs to completely shield surface traces and component radiation signals. At the same time, by dynamically adjusting the actual number of grounding points of the metal planar structure, it can accurately change the resonant frequency of the metal planar structure, thereby comprehensively and efficiently suppressing high and low frequency radio frequency interference generated by traces on the circuit board and related circuit components as radiation sources and coupled to the metal planar structure, without increasing material costs or product space occupation. It is perfectly compatible with various wireless communication products such as gateways and routers that rely on circuit board traces to transmit signals and have high space constraints.

[0053] In some embodiments of the present invention, such as Figure 1 As shown, there are four grounding points on the metal planar structure 120. Two of the grounding points are reference grounding points 131, and the other two are adjustment grounding points 132. The two reference grounding points 131 are connected to the grounding terminal of the circuit board 110, and the two adjustment grounding points 132 are connected to the grounding terminal of the circuit board 110 through the control component 150.

[0054] The control component 150 can be a switching diode.

[0055] Four grounding points are set on the metal planar structure and divided into two different grounding types. Two of the adjustable grounding points are connected to the grounding terminal of the circuit board through the control component to achieve controllable adjustment of the conduction state. The other two grounding points are directly connected to the grounding terminal of the circuit board to form a fixed grounding path. This design is not a simple stacking of numbers, but a composite grounding system of "fixed grounding + controllable adjustment" built by combining the resonant characteristics of the metal planar structure. Its core is to ensure the basic charge discharge capability through the directly grounded grounding point, and then to achieve dynamic adjustment of the number of grounding points by controlling the on and off of the other two grounding points with the help of the control component. The overall layout needs to match the half-wavelength parameter of the radio frequency interference signal to adapt to the resonance suppression requirements. Specifically, the overall layout can be determined by electromagnetic simulation software.

[0056] In this embodiment, the “two fixed and two controllable” layout of the four grounding points not only strengthens the basic charge discharge and grounding stability through the two directly grounded grounding points, but also allows for flexible adjustment of the actual number of grounding points connected to the metal plane by controlling the on / off state of the other two grounding points through the control components, thereby precisely changing the resonant frequency of the metal plane structure.

[0057] In some embodiments of the present invention, two reference grounding points 131 are disposed on the first side of the metal planar structure 120, and the distance between the two reference grounding points 131 is half the wavelength of the radio frequency interference signal. Two adjustment grounding points 132 are disposed on the second side of the metal planar structure 120, and the distance between the two adjustment grounding points 132 is half the wavelength of the radio frequency interference signal. The first side and the second side are arranged opposite to each other.

[0058] In this embodiment of the invention, two reference grounding points are set as fixed grounding basic components on the first side of the metal planar structure, and the distance between them strictly matches the half wavelength of the radio frequency interference signal. Two adjustable grounding points are set as dynamic control core components on the second side opposite to the first side, and their distance is also consistent with the half wavelength of the radio frequency interference signal. The core logic of this layout is that the metal planar structure is equivalent to multiple microstrip patch antennas connected in series, and the half-wavelength distance is the key dimension for the microstrip patch antenna to form resonance. By setting the grounding points on opposite sides according to this distance, the resonance characteristics of the radio frequency interference signal generated by the traces on the circuit board and related circuit components as radiation sources can be accurately corresponded. The reference grounding points provide a stable basic grounding architecture, and the adjustable grounding points realize the controllable switching of the grounding state through control components (such as switching diodes). Thus, through the combination of "reference grounding points + adjustable grounding points", the equivalent resonance parameters of the metal planar structure can be accurately changed, ensuring that its resonant frequency can flexibly avoid the product's operating frequency and achieve directional suppression of radio frequency interference.

[0059] In some embodiments of the present invention, the distance between the center of each grounding point and the corresponding side edge does not exceed 1 / 10 of half the wavelength of the radio frequency interference signal.

[0060] In this embodiment of the invention, it is specified that the distance between the center of each grounding point and the corresponding side edge does not exceed 1 / 10 of half the wavelength of the radio frequency interference signal. The core logic is that the metal planar structure is equivalent to multiple microstrip patch antennas connected in series. The resonance characteristics formed by the radio frequency interference signal on the metal plane are mainly determined by the electromagnetic field distribution in the edge region. This distance limit can ensure that the grounding point is accurately applied to the resonance sensitive area, avoiding the failure or attenuation of the control of resonance parameters due to the grounding point being far from the edge. At the same time, in conjunction with the reference grounding point and the adjustable grounding point set at a relative half-wavelength spacing on the side, the control accuracy of the resonant frequency of the metal planar structure is further enhanced. This ensures that by dynamically switching the grounding state of the grounding point, the operating frequency of the product can be stably and efficiently avoided, and the radio frequency interference generated by the traces on the circuit board and related circuit components as radiation sources and coupled to the metal plane can be specifically suppressed.

[0061] In some embodiments of the present invention, the metal planar structure is at least one of the following: a heat sink for an electronic device, a metal region on a circuit board, or a housing for an electronic device.

[0062] The metal planar structure is defined as at least one of the following: heat sink of electronic device, metal area on circuit board, or electronic device casing. The core of this design is to reuse the inherent large-area metal components inside the electronic device as the carrier for the radio frequency interference suppression scheme, rather than adding an additional independent metal structure. This approach can balance the practicality and economy of the solution, and can also achieve flexible adaptation based on the different carrier properties. Among them, the heat sink, as a core heat dissipation component with high conductivity, can integrate grounding points and control components without affecting the heat conduction path. The PCB metal area, being close to the radiation source, can achieve on-board solution integration and shorten the control signal path. The metal casing can achieve dynamic control of the resonant frequency at the whole device level. Moreover, all three types of carriers have metal conduction characteristics that meet the conditions for radio frequency interference coupling and resonance, and can be adapted to the core control logic of this invention.

[0063] This embodiment's limitation on the metal planar structure carrier achieves both high compatibility and low modification cost. Because it directly reuses the inherent components of the equipment without adding new hardware and with minimal modifications, it can be adapted to various electronic devices across different categories. It also balances interference suppression with the synergy of the original functions of the equipment. The heat sink placement avoids the heat-conducting core, the grounding point of the PCB metal area can enhance grounding performance, and the adjustment of the metal shell does not affect the protection capability, achieving functional reuse without conflict. Furthermore, it improves the universality of the solution and the adaptability to product iteration. It achieves cross-domain adaptation by relying on a general metal structure, and there is no need to redesign the core logic when iterating products, which greatly shortens the iteration cycle.

[0064] In some embodiments of the present invention, such as Figure 1As shown, at least one via 170 is also provided on the metal planar structure 120. The via 170 is located on the resonant path corresponding to half the wavelength of the radio frequency interference signal on the metal planar structure 120, and is used to cooperate with the grounding point to disrupt the resonant condition of the metal planar structure 120.

[0065] At least one via 170 is also provided on the metal planar structure. The via 170 is not randomly arranged. Its specific location and size need to be determined based on the half wavelength of the radio frequency interference signal. Then, the resonance distribution of the metal planar structure under different parameters is simulated by electromagnetic simulation to finally lock the optimal parameters. Its core function is to cooperate with the grounding point 130 on the metal planar structure 120. Through the physical interruption of the resonance path by the via 170 and the discharge of induced charge by the grounding point 130, the resonance conditions formed by the coupling of radio frequency interference signal in the metal planar structure 120 are destroyed, thus forming a dual resonance suppression logic of "physical blocking + charge discharge".

[0066] In this embodiment, the via configuration can form a complementary resonance suppression system with the grounding point. Based on the half-wavelength of the radio frequency interference signal and determined by electromagnetic simulation, its position and size can be precisely applied to the resonant strong electric field region of the metal planar structure. This not only makes up for the shortcomings of a single grounding point in truncating the resonant path, but also significantly reduces the resonance intensity of the metal planar structure through dual suppression logic, effectively improving the comprehensiveness and stability of radio frequency interference suppression. At the same time, it does not require the addition of complex additional components, thus balancing the accuracy and low cost of the solution.

[0067] In some embodiments of the present invention, the number of vias 170 is positively correlated with the area of ​​the metal planar structure 120. When the area of ​​the metal planar structure 120 increases by a rectangular region with half the wavelength of the radio frequency interference signal as the long side, the number of vias 170 increases by at least one.

[0068] The number of vias is positively correlated with the overall area of ​​the metal planar structure, and a specific rule for increasing the number is defined. That is, when the area of ​​the metal planar structure expands by a rectangular area with half the wavelength of the radio frequency interference signal as the long side, the number of vias increases by at least one. This rule is based on the characteristic that the long side size of the rectangular area is easy to resonate with the half wavelength of the radio frequency interference, ensuring that the resonance risk area of ​​the newly added area can be covered by the vias. This avoids blindly stacking the number of vias and can adapt to the resonance suppression requirements of metal planar structures of different areas.

[0069] The positive correlation design between the number of vias and the area of ​​the metal plane in this embodiment, along with the corresponding incremental rules, allows the via layout to precisely match the area expansion of the metal plane. By adding at least one via for the newly added half-wavelength long-side rectangular resonance risk area, the resonance path of the newly added area can be cut off in time, forming a resonance destruction system that works in tandem with the grounding point. This ensures the comprehensiveness of interference suppression for large-area metal planes, avoids the cost increase and structural impact caused by redundant via layout, and improves the adaptability of the solution to metal planes of different sizes.

[0070] Furthermore, regarding the locations of the radiation source and the grounding point, the radiation source is typically positioned between a quarter wavelength (λ / 4) and the grounding point at the edge of the metal plane. At this location, the transmission impedance is close to 50Ω, achieving optimal impedance matching and ensuring efficient signal transmission with minimal loss. The relationship between the radiation source and the grounding point is close: the grounding point serves as the end point of the current loop. The radiation source is close to the grounding point but maintains a λ / 4 distance, both enhancing the radiation field strength through reflection from the ground plane and avoiding impedance mismatch due to excessive proximity. The via's location needs to be cleverly positioned between the radiation source and the object being interfered with (usually the receiving chip or receiving antenna). By increasing the physical distance of the interference current loop, the electromagnetic coupling of the interference signal to the object being interfered with is effectively weakened, significantly improving the antenna's anti-interference capability. The coordinated optimization of the positions of these three elements directly determines the anti-interference performance.

[0071] In some embodiments of the present invention, a current detection unit (not shown in the figure) is provided in the connection path between the two grounding points of the control component. The current detection unit is connected to the main control chip and is used to monitor the conduction current of the grounding point in real time. When the current is abnormal, it sends an abnormal signal to the main control chip.

[0072] The addition of the current detection unit in this embodiment can capture the conduction current status of the grounding point connected to the switching component in real time, and can realize the timely reporting of abnormal signals through linkage with the main control chip. This not only avoids the interruption of the radio frequency interference suppression scheme due to the failure of the grounding point due to abnormal current, but also provides accurate status basis for the subsequent adjustment and control strategy of the main control chip. Without adding complex circuits, the reliability and fault self-sensing capability of the entire interference suppression system are greatly improved.

[0073] The following is a specific example to explain the system for suppressing radio frequency interference provided by the embodiments of the present invention.

[0074] Figure 2 A schematic diagram of a single microstrip patch antenna; Figure 3 A schematic diagram showing the direction of the radiated electric field corresponding to a single microstrip patch antenna; Figure 4 This is a schematic diagram of two microstrip patch antennas; Figure 5Schematic diagram of the radiation electric field directions corresponding to two microstrip patch antennas; Figure 6 Schematic diagram of the first state of the metal plane structure; Figure 7 Schematic diagram of the second state of the metal plane structure; Figure 8 Schematic diagram of the simulation gain curve; 1. The interference radiation principle of this system: 1) As Figure 2 shown, the core of this system is equivalent to a microstrip patch antenna (Patch Antenna). The radiation principle is mainly based on the radiation of the edge field of the resonant cavity formed between the patch and the ground plane. The radiation electric field direction is as Figure 3 shown; The patch antenna consists of a dielectric substrate, a bottom metal ground plane (i.e., the circuit board in this application), and a top rectangular metal patch (i.e., the metal plane structure in this application). The patch length is usually about half wavelength (λ / 2), which will form resonance; A quasi-TEM mode electromagnetic field distribution is formed between the patch and the ground plane. At resonance, the electric field at the edge of the patch (radiating edge) is perpendicular to the ground plane, and the electric field directions on the left and right are opposite. The magnetic field is distributed along the edge, forming an equivalent magnetic current (MC) radiation, resulting in the radiation of electromagnetic waves by the edge field. The main radiation direction is perpendicular to the patch plane.

[0075] 2) The above is the radiation principle of a single microstrip patch antenna. In fact, the size of the metal plane is much larger than the size of λ / 2, which is equivalent to multiple microstrip patch antennas combined together. As Figure 4 shown, for two microstrip antennas, the two planes radiate electromagnetic waves outward simultaneously, and the main radiation direction is perpendicular to the patch plane. The radiation electric field direction is as Figure 5 shown. At the resonant frequency (the position with a length of λ / 2), the electric field directions on the left and right sides are the same, and the electric field direction in the middle is opposite, forming two radiation fields with opposite directions.

[0076] 2. The control principle of this system: 1) According to the above radiation principle, resonance will occur at the position where the length of the metal plane structure is λ / 2, and the radiation ability is enhanced. Then, it is only necessary to destroy the resonance point condition or change the resonance frequency to ensure that the resonance point of the metal plane structure is not at the frequency point where the electronic device operates. The resonance frequency of the metal plane structure can be changed by grounding the appropriate position of the metal plane structure and digging holes at the appropriate position on the metal plane structure.

[0077] 2) To completely disrupt the resonant frequency of the metal planar structure, it is necessary to increase the number of grounding points as much as possible to ensure that the voltage level of each point is the same, so as to minimize radiation. However, this is unlikely to be achieved in actual products, as there are not enough places to place grounding points. Only a limited number of four or five points can be placed to change the resonant frequency of the metal planar structure, as long as they are avoided from the operating frequency of electronic equipment. In this way, electromagnetic simulation software can be used to determine the number and location of grounding points, as well as the size and location of vias on the metal planar structure.

[0078] 3) This application verifies data in two states; As shown in Figure 6, in the first state of the metal plane, two grounding points 610 are grounded, and one via 620 is used: that is... Figure 1 When the I / O pin of the main control chip outputs a low level, the switching diode is turned off, which is equivalent to connecting only two ground points and one via on the metal planar structure. Figure 8 As shown in the simulation, the gain curve is as follows: Figure 8 As shown by line B in the middle.

[0079] As shown in Figure 7, in the second state of the metal plane, four grounding points 710 are grounded, including two reference grounding points 711 and two adjustment grounding points 712, and one via 720: that is... Figure 1 The main control chip outputs a high level at its I / O pin (high level is generally 1.8V-5V, depending on the switching diode). This turns on the switching diode, equivalent to connecting four grounding points and one via on a metal planar structure. Both reference grounding points 711 and two adjustment grounding points 712 are grounded. Figure 8 As shown in the simulation, the gain curve is as follows: Figure 8 As shown by line C in the middle.

[0080] 4) From the above simulation data (such as...) Figure 8 As shown in the diagram, line A represents the original state (metal planar structure with no grounding point and no holes), line B represents two grounding points and holes, and line C represents four grounding points and holes. Different grounding points and holes correspond to different radiation gains, like a seesaw, fluctuating up and down. If low-frequency radiation power is desired, only two grounding points are needed (e.g.,...). Figure 6 As shown); if a low radiated power in the high-frequency band is desired, four grounding points are required (e.g. Figure 7 (As shown). Therefore, products operating in different frequency bands require different grounding points and need dynamic adjustment capabilities. In this embodiment of the invention, a switching diode is added to the grounding position of the metal planar structure to control the grounding at that point, which solves this problem and achieves the purpose of dynamically controlling interference signals.

[0081] about Figure 8 Simulation data: 1. Correspondence between coordinate axes and data: The horizontal axis (Freq[GHz]) represents the frequency of the interference signal, covering a range of 5.125~5.875GHz (corresponding to the 5GHz WiFi operating frequency band of routers and other devices), which is the mid-to-high frequency interference range that the solution focuses on. The vertical axis (gain) represents the radiation gain of the metal planar structure at the corresponding frequency. The three lines A, B, and C correspond to three processing states, and the suppression effect of each scheme can be directly judged by the height of the curve.

[0082] 2. The core significance of the curve trend: Line A (without grounding point or opening) is the "reference control group". Its gain value is the highest in the entire frequency band, indicating that the interference radiation of the metal plane is the strongest when there is no treatment. The gain of line B (two grounding points + opening) is significantly lower than that of line A in the low frequency band (5.125~5.375GHz), while the gain in the high frequency band (above 5.5GHz) is somewhat improved, proving that this solution has a good effect on suppressing low frequency interference, but a limited effect on high frequency interference. The C-line (four grounding points + openings) has the lowest gain among the three curves in the high-frequency band (5.5~5.875GHz), indicating that this scheme has the best suppression effect on high-frequency interference and perfectly matches the design logic of "dynamically switching the number of grounding points".

[0083] Secondly, this invention introduces a method for suppressing radio frequency interference, which is applied to a system for suppressing radio frequency interference. The system includes a circuit board and a metal planar structure arranged opposite to each other. At least two grounding points are provided on the metal planar structure. A portion of the at least two grounding points is connected to the grounding terminal of the circuit board, and the other portion of the grounding points is connected to the grounding terminal of the circuit board through a control component.

[0084] Figure 9 This is a flowchart illustrating the method for suppressing radio frequency interference provided in an embodiment of the present invention; like Figure 9 As shown, the method for suppressing radio frequency interference includes the following steps: S910, the main control chip outputs a low-level control signal to cut off the control components, and a part of the grounding point of the metal planar structure is connected to the grounding terminal of the circuit board, while the other part of the grounding point is no longer grounded; The S920 main control chip outputs a high-level control signal to turn on the control components, connecting all grounding points of the metal planar structure to the grounding terminal of the circuit board.

[0085] In some embodiments of the present invention, before the main control chip outputs a low-level control signal to cut off the control components, and before a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points stop grounding, i.e., before S910, the method further includes: Real-time acquisition and identification of the primary operating frequency band of electronic devices; The main control chip outputs a low-level control signal, which cuts off the control components. A portion of the grounding point on the metal planar structure is connected to the ground terminal of the circuit board, while the other portion of the grounding point is de-grounded, i.e., S910, which includes: When the first operating frequency band is low, the main control chip outputs a low-level control signal, causing the control components to be cut off. Part of the grounding point on the metal planar structure is connected to the grounding terminal of the circuit board, while the other part of the grounding point is no longer grounded. Figure 7 As shown, the two reference grounding points 711 are grounded, while the two adjustment grounding points 712 are not grounded.

[0086] The main control chip outputs a high-level control signal to turn on the control components. All grounding points of the metal planar structure are connected to the ground terminal of the circuit board, i.e., S920, including: When the first operating frequency band is high-frequency, the main control chip outputs a high-level control signal to turn on the control components, connecting all grounding points of the metal planar structure to the grounding terminal of the circuit board. For example... Figure 7 As shown, the two reference grounding points 711 are grounded, and the two adjustment grounding points 712 are also grounded.

[0087] The low-frequency band can be 5.125~5.375GHz, and the high-frequency band can be 5.5~5.875GHz.

[0088] The method for suppressing radio frequency interference provided in this invention involves setting up opposing circuit boards and metal planar structures, and configuring at least two grounding points on the metal planar structure. By changing the actual grounding state of the grounding points, the resonant frequency of the metal planar structure can be flexibly adjusted, thereby specifically suppressing radio frequency interference generated by radiation sources on the circuit board and coupled to the metal planar structure. Compared with existing solutions that rely on radio frequency shielding devices, absorbing materials, or multilayer PCB technology, this method not only eliminates the need for any additional devices or high-order structures, but also significantly reduces product manufacturing costs simply by optimizing existing material forms. It also maintains the original spatial layout of the product, avoiding additional space occupation, and is compatible with various wireless communication products with high space constraints, such as gateways and routers. By avoiding the product's operating frequency, it achieves comprehensive and precise suppression of high and low frequency radio frequency interference, greatly improving the radio frequency interference suppression effect and possessing strong adaptability and practicality.

[0089] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0090] The functional blocks shown in the above-described structural diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this invention are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, read-only memory (ROM), flash memory, erasable read-only memory (EROM), floppy disks, compact disc read-only memory (CD-ROM), optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0091] It should also be noted that the exemplary embodiments mentioned in this invention describe methods or systems based on a series of steps or apparatus. However, this invention is not limited to the order of the steps described above; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0092] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0093] The above description is merely a specific embodiment of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A system for suppressing radio frequency interference, characterized in that, Includes relatively arranged circuit boards and metal planar structures; The metal planar structure has at least two grounding points. Changing the actual grounding state of the grounding points can change the resonant frequency of the metal planar structure to suppress radio frequency interference. The radio frequency interference is caused by radio frequency interference signals generated by radiation sources on the circuit board and coupled to the metal planar structure.

2. The system according to claim 1, characterized in that, At least one of the two grounding points is connected to the ground terminal of the circuit board, and the other part of the grounding points is connected to the ground terminal of the circuit board through a control component.

3. The system according to claim 2, characterized in that, The control component is used to control another portion of the grounding points to ground or stop grounding, thereby changing the actual number of grounding points in the metal planar structure.

4. The system according to claim 3, characterized in that, The control component is used to switch on and off by receiving a level control signal. When a low-level control signal is received, the control component is turned off, a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points are stopped from being grounded. When a high-level control signal is received, the control component is turned on, and all the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

5. The system according to claim 2, characterized in that, When the first operating frequency band of the electronic device is low frequency, the control component controls a portion of the grounding points of the metal planar structure to connect to the grounding terminal of the circuit board, while the other portion of the grounding points are de-grounded; when the first operating frequency band of the electronic device is high frequency, the control component controls all the grounding points of the metal planar structure to connect to the grounding terminal of the circuit board.

6. The system according to claim 2, characterized in that, The metal planar structure has four grounding points, two of which are reference grounding points and the other two are adjustable grounding points. The two reference grounding points are connected to the grounding terminal of the circuit board, and the two adjustable grounding points are connected to the grounding terminal of the circuit board through the control component.

7. The system according to claim 6, characterized in that, Two reference grounding points are located on the first side of the metal planar structure, and the distance between the two reference grounding points is half the wavelength of the radio frequency interference signal. Two adjustment grounding points are located on the second side of the metal planar structure, and the distance between the two adjustment grounding points is half the wavelength of the radio frequency interference signal. The first side and the second side are arranged opposite to each other.

8. The system according to claim 7, characterized in that, The distance between the center of each grounding point and its corresponding side edge does not exceed 1 / 10 of half the wavelength of the radio frequency interference signal.

9. The system according to claim 1, characterized in that, The metal planar structure is at least one of the following: a heat sink for an electronic device, a metal area on the circuit board, or the casing of the electronic device.

10. The system according to claim 1, characterized in that, The metal planar structure is also provided with at least one via, which is located on the resonant path corresponding to half the wavelength of the radio frequency interference signal on the metal planar structure.

11. The system according to claim 10, characterized in that, The number of vias is positively correlated with the area of ​​the metal planar structure. When the area of ​​the metal planar structure increases by a rectangular region with half the wavelength of the radio frequency interference signal as its long side, the number of vias increases by at least one.

12. A method for suppressing radio frequency interference, characterized in that, A system for suppressing radio frequency interference includes a circuit board and a metal planar structure disposed opposite each other; the metal planar structure has at least two grounding points, a portion of which is connected to the ground terminal of the circuit board, and the other portion of which is connected to the ground terminal of the circuit board via a control component; the method includes: The main control chip outputs a low-level control signal to cut off the control components. A portion of the grounding point of the metal planar structure is connected to the grounding terminal of the circuit board, while the other portion of the grounding point is no longer grounded. The main control chip outputs a high-level control signal to turn on the control components, and all grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

13. The method according to claim 12, characterized in that, Before the main control chip outputs a low-level control signal to cut off the control components, and before a portion of the grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, and the other portion of the grounding points are no longer grounded, the method further includes: Real-time acquisition and identification of the primary operating frequency band of electronic devices; The main control chip outputs a low-level control signal to cut off the control components. A portion of the grounding point of the metal planar structure is connected to the ground terminal of the circuit board, while another portion of the grounding point is de-grounded, including: When the first operating frequency band is a low frequency band, the main control chip outputs a low-level control signal to cut off the control component, and a part of the grounding point of the metal planar structure is connected to the grounding terminal of the circuit board, while the other part of the grounding point is stopped from being grounded. The main control chip outputs a high-level control signal to turn on the control components. All grounding points of the metal planar structure are connected to the grounding terminal of the circuit board, including: When the first operating frequency band is a high-frequency band, the main control chip outputs a high-level control signal to turn on the control component, and all grounding points of the metal planar structure are connected to the grounding terminal of the circuit board.

Images