CN115062573A - Method for reducing high-frequency noise of NCSI cable and interconnection device - Google Patents
Method for reducing high-frequency noise of NCSI cable and interconnection device Download PDFInfo
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Abstract
The invention belongs to the technical field of server noise reduction processing, and particularly provides a method for reducing high-frequency noise of an NCSI cable and an interconnection device, wherein the device comprises a high-speed network card and a mainboard; the high-speed network card and the mainboard are respectively provided with an NCSI interface; the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a NCSI cable with shielding design; the mainboard is also provided with a high-frequency band-stop filter circuit; the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit. The NCSI cable with the shielding design sequentially comprises an insulating layer, a shielding layer and a wire core from outside to inside; the wire core comprises a signal wire, a power wire, a clock wire and a ground wire; the ground line is connected with the shielding layer. Necessary EMC design is carried out on the NCSI signal at the main board end and the NCSI cable, EMI radiation noise of the NCSI signal and the NCSI cable is reduced, the problem that no countermeasure can be solved when the product is subjected to EMC test is solved, test efficiency is effectively improved, and test cost is reduced.
Description
Technical Field
The invention relates to the technical field of server noise reduction processing, in particular to a method and an interconnection device for reducing high-frequency noise of NCSI cables.
Background
In the design of a general server, in order to ensure information security, reduce electromagnetic interference, improve anti-interference characteristics and realize longer transmission distance, a high-speed network card with an optical interface is widely used, and supporting the NCSI protocol becomes a development trend of the high-speed network card. The BMC of the server can be remotely accessed through the NCSI, and intelligent management of the server is achieved.
Because the NCSI signal includes a data signal, a power supply, and a single-ended clock signal, the external network card is usually connected to the NCSI signal at the motherboard end via a non-shielded cable, and the NCSI signal may cause serious EMI radiation noise via an interconnection cable, which causes the radiation emission of the server to fail to meet the regulatory limit requirement during EMC testing.
The existing method generally aims at NCSI cable treatment, aluminum-plastic shielding is added, the actual EMC test result is unknown, and the actual EMC test result can only pass experimental verification; secondly, low-pass filtering such as capacitance is added to a clock signal of the NCSI, a method for processing the NCSI signal is lacked at the present stage, EMI radiation noise caused by 50MHz clock frequency doubling can not be solved through shielding, and the main reason is that most NSCI interfaces are non-shielding interfaces, and an NCSI cable shielding layer is isolated and suspended, so the EMI radiation noise can be aggravated; adding capacitance to ground as a low pass filter can severely affect signal quality.
Disclosure of Invention
At present, a method for processing NCSI signals is lacked, EMI radiation noise caused by 50MHz clock frequency multiplication cannot be solved through shielding, and the main reason is that most NSCI interfaces are non-shielding interfaces, and an NCSI cable shielding layer is isolated and suspended, so the EMI radiation noise is aggravated; the invention provides a method for reducing high-frequency noise of an NCSI cable and an interconnection device.
In a first aspect, the technical solution of the present invention provides a method for reducing high-frequency noise of an NCSI cable, including the following steps:
a high-frequency band-stop filter circuit is arranged at the end of the mainboard;
connecting an NCSI interface at the end of the main board with the input end of the high-frequency band-stop filter circuit;
the output end of the high-frequency band-stop filter circuit is connected with a management chip of the mainboard;
and connecting the NCSI interface of the high-speed network card with the NCSI interface at the end of the main board through a shielding NCSI cable.
Because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is very fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often exceeds the requirements of regulations in an electromagnetic compatibility test, a common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency multiplication point is difficult to be effectively inhibited; the problem that the frequency multiplication point of the clock signal exceeds the standard can be solved in a targeted manner by adopting the active band elimination filter on the premise of not influencing the quality of the clock signal.
Further, the step of arranging the high-frequency band-stop filter circuit at the end of the main board comprises:
setting an input signal input low-pass filter and a high-pass filter at the end of a main board;
the output signals of the low-pass filter and the high-pass filter are input to an in-phase proportional operational amplifier circuit.
Further, the step of connecting the NCSI interface of the motherboard end with the input end of the high-frequency band-stop filter circuit includes:
the signal of the NCSI interface at the main board end is simultaneously applied to the low-pass filter and the high-pass filter.
Further, the step of connecting the output end of the high-frequency band-stop filter circuit with the management chip of the mainboard comprises:
and connecting the output signal of the in-phase proportional operational amplification circuit with a management chip of the mainboard.
Further, in the step of connecting the NCSI interface of the high-speed network card to the NCSI interface of the main board end through the shield NCSI cable, the step of designing the shield NCSI cable includes:
the NCSI cable bare multi-core ground wire is connected with the shielding layer of the NCSI cable in a low-impedance mode.
Because most NCSI interfaces are plastic interfaces, the conventional shielding layer is difficult to be grounded at two ends, low-impedance connection can be realized through the exposed multi-core ground wire and the shielding layer, the shielding layer and the metal case are reliably lapped, and EMI radiation noise is effectively reduced.
Necessary EMC design is carried out on the NCSI signal at the main board end and the NCSI cable, EMI radiation noise of the NCSI signal and the NCSI cable is reduced, the problem that no countermeasure can be solved when the product is subjected to EMC test is solved, test efficiency is effectively improved, and test cost is reduced.
In a second aspect, the technical solution of the present invention further provides an interconnection device for reducing high-frequency noise of an NCSI cable, including a high-speed network card and a motherboard;
the high-speed network card and the mainboard are respectively provided with an NCSI interface;
the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a shielding NCSI cable;
the mainboard is also provided with a high-frequency band-stop filter circuit;
the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit.
Because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is very fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often exceeds the requirements of regulations in an electromagnetic compatibility test, a common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency multiplication point is difficult to be effectively inhibited; the problem that the frequency multiplication point of the clock signal exceeds the standard can be solved in a targeted manner by adopting the active band-stop filtering on the premise of not influencing the quality of the clock signal.
Further, the shielding NCSI cable sequentially comprises an insulating layer, a shielding layer and a wire core from outside to inside;
the wire core comprises a signal wire, a power wire, a clock wire and a ground wire;
the ground line is connected with the shielding layer. Because most NCSI interfaces are plastic interfaces, the conventional shielding layer is difficult to be grounded at two ends, low-impedance connection can be realized through the exposed multi-core ground wire and the shielding layer, the shielding layer and the metal case are reliably lapped, and EMI radiation noise is effectively reduced.
Furthermore, the high-frequency band-stop filter circuit comprises a low-pass filter, a high-pass filter and an in-phase proportional operational amplifier circuit;
the input signal of the NCSI interface of the mainboard is simultaneously input into a low-pass filter and a high-pass filter, the output ends of the low-pass filter and the high-pass filter are connected with an in-phase proportional operational amplifier circuit, and the cut-off frequency of the low-pass filter is smaller than that of the high-pass filter.
Further, the in-phase proportional operational amplifier circuit comprises an in-phase proportional operational amplifier;
the high-pass filter comprises a first capacitor, a second capacitor and a first resistor;
an input signal of an NCSI interface of the mainboard is connected to the positive input end of the in-phase proportional operational amplifier through a first capacitor and a second capacitor which are connected in series;
the connection point of the first capacitor and the second capacitor is connected to the output end of the in-phase proportional operational amplifier through a first resistor;
the low-pass filter comprises a second resistor, a third resistor and a third capacitor;
an input signal of an NCSI interface of the mainboard is connected to the positive input end of the in-phase proportional operational amplifier through a second resistor and a third resistor which are connected in series;
the connection point of the third resistor and the fourth resistor is grounded through the third capacitor.
Furthermore, the negative input end of the in-phase proportional operational amplifier is grounded through a fourth resistor;
the negative input end of the in-phase proportional operational amplifier is also connected to the output end of the in-phase proportional operational amplifier through a feedback resistor;
the output end of the in-phase proportional operational amplifier is connected with the management chip.
Because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is very fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often exceeds the requirements of regulations in an electromagnetic compatibility test, a common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency multiplication point is difficult to be effectively inhibited; the problem that the frequency multiplication point of the clock signal exceeds the standard can be solved in a targeted manner by adopting the active band-stop filtering on the premise of not influencing the quality of the clock signal.
According to the technical scheme, the invention has the following advantages: necessary EMC design is carried out to main board end NCSI signal and NCSI cable, reduces its EMI radiation noise, avoids the product to find the problem when carrying out the EMC test and has not had the difficult problem that the countermeasure can be solved, effectively improves efficiency of software testing, reduces test cost. Effective inhibition measures are added for predictable risks, repeated verification time of EMC tests is shortened, PCB revising risks caused by unqualified EMC tests are reduced, and research and development costs, EMC test costs and project open periods are reduced.
In addition, the invention has reliable design principle, simple structure and very wide application prospect.
Therefore, compared with the prior art, the invention has prominent substantive features and remarkable progress, and the beneficial effects of the implementation are also obvious.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.
FIG. 1 is a schematic flow diagram of a method of one embodiment of the present invention.
Fig. 2 is a schematic diagram illustrating interconnection between a high-speed network card and a motherboard according to an embodiment of the present invention.
Figure 3 is a schematic diagram of a shielded NCSI cable according to an embodiment of the present invention.
Fig. 4 is a diagram of a high-frequency band-stop filter circuit architecture according to an embodiment of the invention.
Detailed Description
Because the NCSI signal includes a data signal, a power supply, and a single-ended clock signal, the external sampling network card is usually connected to the NCSI signal at the motherboard end through a non-shielded cable, and the NCSI signal may cause severe EMI radiation noise through an interconnection cable, so that the radiation emission of the server does not meet the regulatory limit requirements when performing EMC testing.
The existing method generally aims at the NCSI cable to be processed, aluminum-plastic shielding is added, the actual EMC test result is unknown, and the actual EMC test result can only pass experimental verification; secondly, low-pass filtering such as capacitance is added to a clock signal of the NCSI, a method for processing the NCSI signal is lacked at the present stage, EMI radiation noise caused by 50MHz clock frequency doubling can not be solved through shielding, and the main reason is that most NSCI interfaces are non-shielding interfaces, and an NCSI cable shielding layer is isolated and suspended, so the EMI radiation noise can be aggravated; adding capacitance to ground as a low pass filter can severely affect signal quality.
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The NSCI Network Controller side band Interface.
As shown in fig. 1, embodiment 1 of the present invention provides a method for reducing high-frequency noise of an NCSI cable, including the following steps:
step 1: a high-frequency band-stop filter circuit is arranged at the end of the mainboard;
step 2: connecting an NCSI interface at the end of the main board with the input end of the high-frequency band-stop filter circuit;
and step 3: the output end of the high-frequency band-stop filter circuit is connected with a management chip of the mainboard;
and 4, step 4: and connecting the NCSI interface of the high-speed network card with the NCSI interface at the end of the main board through a shielding NCSI cable.
Because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is very fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often exceeds the requirements of regulations in an electromagnetic compatibility test, a common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency multiplication point is difficult to be effectively inhibited; the problem that the frequency multiplication point of the clock signal exceeds the standard can be solved in a targeted manner by adopting the active band elimination filter on the premise of not influencing the quality of the clock signal.
Embodiment 2 of the present invention provides a method for reducing high-frequency noise of an NCSI cable, including the following steps:
step 1: a high-frequency band-stop filter circuit is arranged at the end of the mainboard;
the method specifically comprises the following steps:
step 11: setting an input signal input low-pass filter and a high-pass filter at the end of a main board;
step 12: the output signals of the low-pass filter and the high-pass filter are input to an in-phase proportional operational amplifier circuit;
step 2: connecting an NCSI interface at the end of the main board with the input end of the high-frequency band-stop filter circuit;
that is, the signal of the NCSI interface at the board side is applied to both the low-pass filter and the high-pass filter.
And step 3: the output end of the high-frequency band-stop filter circuit is connected with a management chip of the mainboard;
correspondingly, the output signal of the in-phase proportional operational amplifier circuit is connected with a management chip of the mainboard;
and 4, step 4: connecting an NCSI interface of the high-speed network card with an NCSI interface at a mainboard end through a shielding NCSI cable; in this step, the step of designing the shield NCSI cable includes:
the NCSI cable bare multi-core ground wire is connected with the shielding layer of the NCSI cable in a low-impedance mode.
Because most NCSI interfaces are plastic interfaces, the conventional shielding layer is difficult to be grounded at two ends, low-impedance connection can be realized through the exposed multi-core ground wire and the shielding layer, the shielding layer and the metal case are reliably lapped, and EMI radiation noise is effectively reduced.
Necessary EMC design is carried out on the NCSI signal at the main board end and the NCSI cable, EMI radiation noise of the NCSI signal and the NCSI cable is reduced, the problem that no countermeasure can be solved when the product is subjected to EMC test is solved, test efficiency is effectively improved, and test cost is reduced.
As shown in fig. 2, embodiment 3 of the present invention further provides an interconnection apparatus for reducing high-frequency noise of an NCSI cable, including a high-speed network card and a motherboard;
the high-speed network card and the mainboard are respectively provided with an NCSI interface;
the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a shielding NCSI cable;
the mainboard is also provided with a high-frequency band-stop filter circuit;
the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit.
Because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is very fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often exceeds the requirements of regulations in an electromagnetic compatibility test, a common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency multiplication point is difficult to be effectively inhibited; the problem that the frequency multiplication point of the clock signal exceeds the standard can be solved in a targeted manner by adopting the active band-stop filtering on the premise of not influencing the quality of the clock signal.
As shown in fig. 2, embodiment 4 of the present invention further provides an interconnection apparatus for reducing high-frequency noise of an NCSI cable, including a high-speed network card and a motherboard;
the high-speed network card and the mainboard are respectively provided with an NCSI interface;
the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a shielding NCSI cable;
the mainboard is also provided with a high-frequency band-stop filter circuit;
the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit.
It should be noted that the management chip may be a BMC chip, and the motherboard is further provided with a clock Buffer and a power supply; the high-level network card also comprises a PCIE interface and two optical ports.
As shown in fig. 3, the shielding NCSI cable sequentially comprises an insulating layer 102, a shielding layer 103 and a wire core 101 from outside to inside;
the wire core comprises a wire core 101B and a ground wire 101A, wherein the wire core 101B comprises a signal wire, a power wire and a clock wire;
the ground line 101A is a bare multi-core ground line, and the ground line 101A is connected to the shielding layer 103. Because most NCSI interfaces are plastic interfaces, the conventional shielding layer is difficult to be grounded at two ends, low-impedance connection can be realized through the exposed multi-core ground wire and the shielding layer, the shielding layer and the metal case are reliably lapped, and EMI radiation noise is effectively reduced.
The interconnection scheme of the NCSI signals in service is shown in FIG. 2, the EMC radiation noise of the NCSI signals passing through the interconnection cable is reduced, and the main solution is as follows: firstly, filtering is carried out from the source, namely thinning; secondly, shielding, namely blocking, is carried out on a signal transmission path.
The source is designed in a sparse way, because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is extremely fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often appears in an electromagnetic compatibility test and exceeds the requirements of regulations, the common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency point is difficult to be effectively inhibited; the problem that the frequency multiplication point of a clock signal exceeds the standard can be solved in a targeted manner by adopting the active band elimination filter on the premise of not influencing the quality of the clock signal, only the in-band-blocking signal is inhibited, and a low-pass filter circuit can be reserved on key signals (RDX, TXD, CRSDV and TXEN) and a power supply according to the requirement by other sparse design.
The transmission path 'block' design is characterized in that the NCSI cable is in a shielding design, space radiation noise of signals, power supplies and clocks on the NCSI cable is reduced, the NCSI can be designed by a design method shown in figure 3 to improve the shielding efficiency of the NCSI cable, most NCSI interfaces are plastic interfaces, a conventional shielding layer is difficult to be in a two-end grounding design, low-impedance connection can be achieved through exposed multiple ground wires and the shielding layer, the shielding layer and a metal case are in reliable lap joint, and EMI radiation noise is effectively reduced.
1) The filtering effect of the band-stop filtering circuit on the concerned frequency point is accurately obtained by comparing and measuring the spectrum analyzer with the field-entering probe before and after adding technical measures;
2) the signal quality is tested through the oscilloscope, and the influence of the band elimination filter on the clock signal can be accurately obtained;
3) the Radiation Emission (RE) test is carried out in a 10 m-method half-wave darkroom, and the final results of the added band-stop filter circuit, the low-pass filter circuit and the NCSI cable shielding design can be accurately obtained.
Effective inhibition measures are added for predictable risks, repeated verification time of EMC tests is shortened, PCB revising risks caused by unqualified EMC tests are reduced, and research and development costs, EMC test costs and project open periods are reduced.
As shown in fig. 2, embodiment 5 of the present invention further provides an interconnection apparatus for reducing high-frequency noise of an NCSI cable, including a high-speed network card and a motherboard;
the high-speed network card and the mainboard are respectively provided with an NCSI interface;
the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a shielding NCSI cable;
the mainboard is also provided with a high-frequency band-stop filter circuit;
the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit.
As shown in fig. 3, the shielded NCSI cable sequentially includes, from outside to inside, an insulating layer 102, a shielding layer 103, and a core 101;
the wire core comprises a wire core 101B and a ground wire 101A, wherein the wire core 101B comprises a signal wire, a power wire and a clock wire;
the ground line 101A is a bare multi-core ground line, and the ground line 101A is connected to the shielding layer 103. Because most NCSI interfaces are plastic interfaces, the conventional shielding layer is difficult to be grounded at two ends, low-impedance connection can be realized through the exposed multi-core ground wire and the shielding layer, the shielding layer and the metal case are reliably lapped, and EMI radiation noise is effectively reduced.
As shown in fig. 4, the high-frequency band-stop filter circuit includes a low-pass filter, a high-pass filter, and an in-phase proportional operational amplifier circuit;
the input signal of the NCSI interface of the mainboard is simultaneously input into a low-pass filter and a high-pass filter, the output ends of the low-pass filter and the high-pass filter are connected with an in-phase proportional operational amplifier circuit, and the cut-off frequency of the low-pass filter is smaller than that of the high-pass filter.
As shown in fig. 2, embodiment 6 of the present invention further provides an interconnection apparatus for reducing high-frequency noise of an NCSI cable, including a high-speed network card and a motherboard;
the high-speed network card and the mainboard are respectively provided with an NCSI interface;
the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a shielding NCSI cable;
the mainboard is also provided with a high-frequency band-stop filter circuit;
the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit.
As shown in fig. 3, the shielded NCSI cable sequentially includes, from outside to inside, an insulating layer 102, a shielding layer 103, and a core 101;
the wire core comprises a wire core 101B and a ground wire 101A, wherein the wire core 101B comprises a signal wire, a power wire and a clock wire;
the ground line 101A is a bare multi-core ground line, and the ground line 101A is connected to the shielding layer 103. Because most NCSI interfaces are plastic interfaces, the conventional shielding layer is difficult to be grounded at two ends, low-impedance connection can be realized through the exposed multi-core ground wire and the shielding layer, the shielding layer and the metal case are reliably lapped, and EMI radiation noise is effectively reduced.
As shown in fig. 4, the high-frequency band-stop filter circuit includes a low-pass filter, a high-pass filter, and an in-phase proportional operational amplifier circuit;
the input signal of the NCSI interface of the mainboard is simultaneously input into a low-pass filter and a high-pass filter, the output ends of the low-pass filter and the high-pass filter are connected with an in-phase proportional operational amplifier circuit, and the cut-off frequency of the low-pass filter is smaller than that of the high-pass filter.
The in-phase proportional operational amplification circuit comprises an in-phase proportional operational amplifier;
the high-pass filter comprises a first capacitor, a second capacitor and a first resistor;
an input signal of an NCSI interface of the mainboard is connected to a positive input end of the in-phase proportional operational amplifier through a first capacitor and a second capacitor which are connected in series;
the connection point of the first capacitor and the second capacitor is connected to the output end of the in-phase proportional operational amplifier through a first resistor;
the low-pass filter comprises a second resistor, a third resistor and a third capacitor;
an input signal of an NCSI interface of the mainboard is connected to the positive input end of the in-phase proportional operational amplifier through a second resistor and a third resistor which are connected in series;
the connection point of the third resistor and the fourth resistor is grounded through the third capacitor.
The negative input end of the in-phase proportional operational amplifier is grounded through a fourth resistor;
the negative input end of the in-phase proportional operational amplifier is also connected to the output end of the in-phase proportional operational amplifier through a feedback resistor;
the output end of the in-phase proportional operational amplifier is connected with the management chip.
Because NSCI signals comprise 50MHZ single-ended square wave clock signals, the rising time of the NSCI signals is very fast, the NSCI signals contain rich high-frequency harmonic components, certain isolated frequency point often exceeds the requirements of regulations in an electromagnetic compatibility test, a common design method is solved by adding low-pass filtering, the quality of the clock signals is affected by the fact that the cut-off frequency of a low-pass filter is too low, and the cut-off frequency of the low-pass filter is not too high due to parasitic effects of components and PCB wiring, so that the frequency multiplication point is difficult to be effectively inhibited; the problem that the frequency multiplication point of the clock signal exceeds the standard can be solved in a targeted manner by adopting the active band-stop filtering on the premise of not influencing the quality of the clock signal.
Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A method of reducing high frequency noise of an NCSI cable, comprising the steps of:
a high-frequency band-stop filter circuit is arranged at the end of the mainboard;
connecting an NCSI interface at the end of the main board with the input end of the high-frequency band-stop filter circuit;
the output end of the high-frequency band-stop filter circuit is connected with a management chip of the mainboard;
and connecting the NCSI interface of the high-speed network card with the NCSI interface at the end of the main board through a shielding NCSI cable.
2. The method of reducing high frequency noise of an NCSI cable of claim 1, wherein the step of providing a high frequency band-stop filter circuit at the motherboard end comprises:
setting an input signal input low-pass filter and a high-pass filter at the end of a main board;
the output signals of the low-pass filter and the high-pass filter are input to an in-phase proportional operational amplifier circuit.
3. The method of reducing high frequency noise of an NCSI cable of claim 2, wherein the step of connecting the NCSI interface of the motherboard end with the input end of the high frequency band-stop filter circuit comprises:
the signal of the NCSI interface at the main board end is simultaneously applied to the low-pass filter and the high-pass filter.
4. The method of reducing high frequency noise of NCSI cable of claim 3, wherein the step of connecting the output end of the high frequency band-stop filter circuit with the management chip of the mainboard comprises:
and connecting the output signal of the in-phase proportional operational amplification circuit with a management chip of the mainboard.
5. The method for reducing high-frequency noise of the NCSI cable according to claim 4, wherein in the step of connecting the NCSI interface of the high-speed network card with the NCSI interface of the main board end through the shielding NCSI cable, the step of NCSI cable shielding design comprises:
the NCSI cable bare multi-core ground wire is connected with the shielding layer of the NCSI cable in a low-impedance mode.
6. An interconnection device for reducing high-frequency noise of NCSI cables is characterized by comprising a high-speed network card and a mainboard;
the high-speed network card and the mainboard are respectively provided with an NCSI interface;
the NCSI interface of the high-speed network card is connected with the NCSI interface of the mainboard through a shielding NCSI cable;
the mainboard is also provided with a high-frequency band-stop filter circuit;
the NCSI interface of the mainboard is connected with a management chip through a high-frequency band-stop filter circuit.
7. The interconnection device for reducing high-frequency noise of the NCSI cable according to claim 6, wherein the shielded NCSI cable comprises an insulating layer, a shielding layer and a wire core in sequence from outside to inside;
the wire core comprises a signal wire, a power wire, a clock wire and a ground wire;
the ground line is connected with the shielding layer.
8. The interconnection device for reducing high-frequency noise of NCSI cables as claimed in claim 7, wherein the high-frequency band-stop filter circuit comprises a low-pass filter, a high-pass filter and an in-phase proportional operational amplifier circuit;
the input signal of the NCSI interface of the mainboard is simultaneously input into a low-pass filter and a high-pass filter, the output ends of the low-pass filter and the high-pass filter are connected with an in-phase proportional operational amplifier circuit, and the cut-off frequency of the low-pass filter is smaller than that of the high-pass filter.
9. The interconnection apparatus for reducing high frequency noise of NCSI cable of claim 8, wherein the in-phase proportional operational amplifier circuit comprises an in-phase proportional operational amplifier;
the high-pass filter comprises a first capacitor, a second capacitor and a first resistor;
an input signal of an NCSI interface of the mainboard is connected to a positive input end of the in-phase proportional operational amplifier through a first capacitor and a second capacitor which are connected in series;
the connection point of the first capacitor and the second capacitor is connected to the output end of the in-phase proportional operational amplifier through a first resistor;
the low-pass filter comprises a second resistor, a third resistor and a third capacitor;
an input signal of an NCSI interface of the mainboard is connected to the positive input end of the in-phase proportional operational amplifier through a second resistor and a third resistor which are connected in series;
the connection point of the third resistor and the fourth resistor is grounded through the third capacitor.
10. The interconnection apparatus for reducing high frequency noise of NCSI cable according to claim 9, wherein the negative input terminal of the non-inverting proportional operational amplifier is grounded through a fourth resistor;
the negative input end of the in-phase proportional operational amplifier is also connected to the output end of the in-phase proportional operational amplifier through a feedback resistor;
the output end of the in-phase proportional operational amplifier is connected with the management chip.
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| CN107463456A (en) * | 2017-08-04 | 2017-12-12 | 郑州云海信息技术有限公司 | A kind of system and method for lifting double netcard NCSI management system switching efficiencies |
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| CN107463456A (en) * | 2017-08-04 | 2017-12-12 | 郑州云海信息技术有限公司 | A kind of system and method for lifting double netcard NCSI management system switching efficiencies |
| WO2019024436A1 (en) * | 2017-08-04 | 2019-02-07 | 郑州云海信息技术有限公司 | System and method for improving dual-network card ncsi management system switching efficiency |
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