阅读说明：本技术 网口滤波器及网络设备 (Network port filter and network equipment ) 是由 廖建兴 于 2019-04-03 设计创作，主要内容包括：一种网口滤波器,包括第一差分链路和第二差分链路,所述第一差分链路上从所述第一输入端口开始顺次串接有第三线圈、第一线圈及第一隔离电容,所述第二差分链路上从所述第二输入端口开始顺次串接有第四线圈、第二线圈及第二隔离电容,其中,所述第三线圈和所述第四线圈构成一自耦电感,所述第一线圈和所述第二线圈构成一共模电感。利用隔离电容取代了传统网络变压器,采用电场的方耦合信号,耦合效果比传统网络变压器更好,相比传统网络变压器的方案,可以大大节省电路板面积。(A network port filter comprises a first differential link and a second differential link, wherein a third coil, a first coil and a first isolation capacitor are sequentially connected in series on the first differential link from a first input port, a fourth coil, a second coil and a second isolation capacitor are sequentially connected in series on the second differential link from a second input port, the third coil and the fourth coil form a self-coupling inductor, and the first coil and the second coil form a common-mode inductor. The isolation capacitor is used for replacing a traditional network transformer, square coupling signals of an electric field are adopted, the coupling effect is better than that of the traditional network transformer, and the circuit board area can be greatly saved compared with the scheme of the traditional network transformer.)

1. A net gape filter, includes first input port, second input port, first output port and second output port, its characterized in that still includes:

the pins at the two ends of the self-coupling inductor are respectively and electrically connected with the first input port and the second input port, and the middle tap of the self-coupling inductor is grounded as a grounding pin;

a common mode inductor having a first coil and a second coil mutually coupled with the first coil, a first end of the first coil being electrically connected to the first input port, a first end of the second coil being electrically connected to the second input port;

a first end of the first isolation capacitor is electrically connected with the second end of the first coil, and the second end of the first isolation capacitor is electrically connected with the first output port; and

a second isolation capacitor, a first end of the second isolation capacitor being electrically connected to the second end of the second coil, a second end of the second isolation capacitor being electrically connected to the second output port.

2. The portal filter of claim 1, further comprising a first bypass capacitor and a second bypass capacitor, a first terminal of said first bypass capacitor being electrically connected to a second terminal of said first isolation capacitor, a second terminal of said first bypass capacitor being connected to digital ground, a first terminal of said second bypass capacitor being electrically connected to a second terminal of said second isolation capacitor, a second terminal of said second bypass capacitor being connected to digital ground.

3. The portal filter of claim 1, further comprising a first voltage divider module and a second voltage divider module, wherein the second end of the first isolation capacitor is electrically connected to the first output port through the first voltage divider module; and the second end of the second isolation capacitor is connected with the second output port through a second voltage division module.

4. The net gape filter of any one of claims 1 to 3, wherein the ground pin of the self-coupling inductor drains the leakage energy to the commercial power network to the ground after passing through the negative pole of the secondary side of the power circuit, the Y capacitor, the negative pole of the primary side of the power circuit in sequence; or

The grounding pin of the self-coupling inductor discharges the discharge energy to the equipment casing and then to the ground through the discharge capacitor and the TSS tube connected with the discharge capacitor in parallel; or

The ground pin of the self-coupling inductor discharges the discharge energy to the equipment shell and then to the ground through the discharge capacitor and the resistor connected with the discharge capacitor in parallel; or

The ground pin of the self-coupling inductor discharges the discharge energy to the equipment shell and then to the ground through the discharge resistor; or

And the grounding pin of the self-coupling inductor discharges the discharge energy to the equipment shell and then to the ground through the TSS pipe.

5. The network port filter according to any one of claims 1 to 3, wherein the self-coupled inductor is disposed on a first outer layer of a circuit board and electrically connected to an arbitrary wiring layer of the circuit board, and a conductor for grounding is provided on a second outer layer of the circuit board opposite to the first outer layer, the conductor being directly opposite to the self-coupled inductor, and a ground pin of the self-coupled inductor is electrically connected to the conductor through a ground via hole provided on the circuit board.

6. The mesh filter of claim 5, wherein said electrical conductor is elongated and has a width of ≧ 20 mil;

on the circuit substrate, the distance between a pad of the grounding pin of the self-coupling inductor and the edge of the ground via hole is 1-10 mil;

on the circuit substrate, the width of a routing path electrically connecting the conductive copper foil and the grounding pad is between 10mil and 30 mil;

and on the circuit substrate, the edge distance between the bonding pads for welding the self-coupling inductor is more than 12 mil.

7. The net gape filter of claim 1 wherein the self-coupled inductor comprises a third coil and a fourth coil, a first end of the third coil is electrically connected to the first input port, a first end of the fourth coil is electrically connected to the second input port, a second end of the fourth coil and a second end of the third coil are center-tapped as ground pins for connection to ground;

on the circuit substrate, the self-coupling inductors and the common-mode inductors on the same differential signal line are arranged along a first direction.

8. A network device comprising a gateway connector and a plurality of gateway filter modules comprising the gateway filters of any of claims 1 to 7, the first and second input ports of each of the gateway filters being connected to the gateway connector by a pair of differential signal lines.

9. The network device of claim 8, wherein a minimum distance between pairs of wires in a same layer that run the same differential signal line is ≧ 10 mils; the vertical projections of the differential signal lines with the same wiring direction of adjacent layers on the same layer are not overlapped; the minimum distance between the vertical projections of the differential signal lines with the same wiring direction of adjacent layers on the same layer is larger than or equal to 5 mil; and the wiring line width of the differential signal line is not less than 4.5 mil.

10. The network device of claim 9, wherein each of the differential signal lines cannot switch layers more than 2 vias.

Technical Field

The application belongs to the technical field of equipment, instruments or electronic products with network communication functions, and particularly relates to a network port filter and network equipment.

Background

The main functions of a conventional network transformer include: transmission and isolation: the electromagnetic coupling characteristic of the network transformer is utilized to transmit signals and block abnormal high voltage; and (3) noise suppression: the purpose of suppressing noise is achieved through a filter and a common mode filter in the network transformer; impedance matching: the purpose of impedance matching is achieved by adjusting the number of turns of the coil, so that signal transmission is facilitated.

The traditional network port transformer adopts a method of electrically isolating primary and secondary sides of the network port transformer to isolate lightning stroke or surge injected from a network port, CS (conducted susceptibility induced by a connected radio frequency field), ESD (Electro-Static discharge) and EFT (Electrical Fast Transient pulse group), and signals are coupled through the network port transformer, so that the coupling of the signals is realized by the method, and lightning stroke and Static electricity are isolated. Furthermore, the following disadvantages are also present: the traditional network transformer occupies a large amount of Printed Circuit Board (PCB) space, and cannot be implemented on very high-density products such as routers, network cameras, computers, servers, gateways, switches, and the like. The limitation of distribution parameters (distributed inductance, distributed capacitance, etc.) of the magnetic core, winding, etc. of the traditional network transformer couples the differential signal through the traditional transformer, which greatly restricts the speed of the differential signal. With the advent of tera routers and tera switches, the upgrading and upgrading of products has been restricted. In addition, the traditional network transformer has high cost and poor consistency of devices.

Disclosure of Invention

In view of this, embodiments of the present application provide a network port filter and a network device, which aim to solve the problem that a traditional network transformer couples differential signals through a transformer, so that the rate of the differential signals is greatly restricted, and the occupied PCB area is large.

A first aspect of the embodiments of the present application provides a network port filter, including a first input port, a second input port, a first output port, and a second output port, further including:

the two ends of the self-coupling inductor are respectively and electrically connected with the first input port and the second input port, and a middle tap of the self-coupling inductor is grounded as a grounding pin;

a common mode inductor having a first coil and a second coil mutually coupled with the first coil, a first end of the first coil being electrically connected to the first input port, a first end of the second coil being electrically connected to the second input port;

a first end of the first isolation capacitor is connected with a second end of the first coil, and the second end of the first isolation capacitor is electrically connected with the first output port; and

and a first end of the second isolation capacitor is connected with a second end of the second coil, and a second end of the second isolation capacitor is electrically connected with the second output port.

In one embodiment, the circuit further comprises a first bypass capacitor and a second bypass capacitor, wherein a first end of the first bypass capacitor is electrically connected to a second end of the first isolation capacitor, a second end of the first bypass capacitor is connected to a digital ground, a first end of the second bypass capacitor is electrically connected to a second end of the second isolation capacitor, and a second end of the second bypass capacitor is connected to a digital ground.

In one embodiment, the power supply further comprises a first voltage division module and a second voltage division module, wherein the second end of the first isolation capacitor is electrically connected with the first output port through the first voltage division module; and the second end of the second isolation capacitor is connected with the second output port through a second voltage division module.

In one embodiment, the ground pin of the self-coupling inductor discharges the discharged energy to the commercial power network and then to the ground through the negative electrode of the secondary end of the power circuit, the Y capacitor and the negative electrode of the primary end of the power circuit in sequence; or

The grounding pin of the self-coupling inductor discharges the discharge energy to the equipment casing and then to the ground through the discharge capacitor and the TSS tube connected with the discharge capacitor in parallel; or

The ground pin of the self-coupling inductor discharges the discharge energy to the equipment shell and then to the ground through the discharge capacitor and the resistor connected with the discharge capacitor in parallel; or

The ground pin of the self-coupling inductor discharges the discharge energy to the equipment shell and then to the ground through the discharge resistor; or

And the grounding pin of the self-coupling inductor discharges the discharge energy to the equipment shell and then to the ground through the TSS pipe.

In one embodiment, the self-coupling inductor is arranged on a first outer layer of a circuit substrate and is electrically connected with any wiring layer of the circuit substrate, a conductor for grounding is arranged on a second outer layer of the circuit substrate opposite to the first outer layer, the conductor is directly opposite to the self-coupling inductor, and a grounding pin of the self-coupling inductor is electrically connected with the conductor through a ground through hole formed in the circuit substrate.

In one embodiment, the electric conductor is a long strip with the width being ≧ 20 mil;

on the circuit substrate, the distance between a pad of the grounding pin of the self-coupling inductor and the edge of the ground via hole is 1-10 mil;

on the circuit substrate, the width of a routing path electrically connecting the conductive copper foil and the grounding pad is between 10mil and 30 mil;

and on the circuit substrate, the edge distance between the bonding pads for welding the self-coupling inductor is more than 12 mil.

In one embodiment, the self-coupled inductor comprises a third coil and a fourth coil, wherein a first end of the third coil is electrically connected with the first input port, a first end of the fourth coil is electrically connected with the second input port, and a second end of the fourth coil and a second end of the third coil are middle taps and are used as grounding pins to be grounded;

on the circuit substrate, the self-coupling inductors and the common-mode inductors on the same differential signal line are arranged along a first direction.

A second aspect of the embodiments of the present application provides a network device, including a network port connector and a plurality of network port filtering modules, where the network port filtering modules include the network port filters provided in the first aspect, and a first input port and a second input port of each network port filter are connected to the network port connector through a pair of differential signal lines.

In one embodiment, the minimum distance between each pair of differential signal lines with the same routing direction in the same layer is ≧ 10 mil; the vertical projections of the differential signal lines with the same wiring direction of adjacent layers on the same layer are not overlapped; the minimum distance between the vertical projections of the differential signal lines with the same wiring direction of adjacent layers on the same layer is larger than or equal to 5 mil; and the wiring line width of the differential signal line is not less than 4.5 mil.

In one embodiment, the number of layer changes of each differential signal line cannot exceed 2 vias.

Has the advantages that: the network port filter comprises a self-coupling inductor, a common-mode inductor, an isolation capacitor and the like, the isolation capacitor is used for replacing a traditional network transformer, a square coupling signal of an electric field is adopted, and the coupling effect is better than that of the traditional network transformer. The physical characteristic of the capacitor for blocking direct current and alternating current is utilized to prevent the direct current component of the signal of the network from entering a post-stage circuit. In addition, the capacitance capacity can adjust the frequency low-frequency cut-off point of the signal passing through the network, and the larger the capacitance capacity is, the lower the low-frequency cut-off point is, and meanwhile, more low-frequency noise can be coupled. Moreover, compared with the scheme of the traditional network transformer, the circuit board area can be greatly saved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a circuit block diagram of a network device according to an embodiment of the present application;

fig. 2 is a circuit diagram of a net gape filter according to a first embodiment of the present application;

fig. 3 is a circuit diagram of a net gape filter according to a second embodiment of the present application;

FIG. 4 is a layout wiring diagram of the net port filter shown in FIG. 2 or FIG. 3 on a circuit board;

FIG. 5 is a layout diagram of the circuit substrate of the Wifi repeater of the network interface filter shown in FIG. 2;

fig. 6 is a schematic diagram of a path of lightning strike current of the net gape filter shown in fig. 2 being discharged from an AC-DC power panel.

Fig. 7 is a layout wiring diagram of the network port filter shown in fig. 3 on a circuit substrate of a switch;

fig. 8 is a top and bottom layout diagram of the portal filter of fig. 3 on a circuit substrate of a switch;

fig. 9 is a wiring diagram of the differential signal lines between the network port connector and the network port filter in the same layer and adjacent layers of the circuit substrate according to the embodiment of the present application.

Fig. 10 is a schematic diagram illustrating a structure of the network interface filter shown in fig. 5 mounted between a circuit substrate of the Wifi repeater and an AC-DC power board.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

Referring to fig. 1, the network device provided in the embodiment of the present application includes a network port connector 30 and a plurality of network port filtering modules, where each network port filtering module includes a network port filter 10, and a first input port and a second input port of each network port filter 10 are connected to the network port connector 30 through a pair of differential signal lines 20.

Referring to fig. 2, a circuit diagram of a port filter according to an embodiment of the present application only shows a portion related to the embodiment for convenience of description, and the detailed description is as follows:

the net mouth filter 10 includes a first input port 11, a second input port 12, a first output port 13, and a second output port 14, and the net mouth filter 10 further includes a self-coupling inductor 110, a common mode inductor 120, a first isolation capacitor 131, and a second isolation capacitor 132.

Pins at two ends of the self-coupling inductor 110 are electrically connected with the first input port 11 and the second input port 12 respectively, and a middle tap of the self-coupling inductor 110 is grounded as grounding pins 111 and 112; the common mode inductor 120 has a first coil 122 and a second coil 124 mutually coupled with the first coil 122, a first end of the first coil 122 is electrically connected to the first input port 11, and a first end of the second coil 124 is electrically connected to the second input port 12; a first end of the first isolation capacitor 131 is connected to the second end of the first coil 122, and a second end of the first isolation capacitor 131 is electrically connected to the first output port 13; and a second isolation capacitor 132, a first end of the second isolation capacitor 132 is connected to the second end of the second coil 124, and a second end of the second isolation capacitor 132 is electrically connected to the second output port 14.

The center taps (ground pins 111, 112) of the self-coupled inductors 110 in the net-port filter 10 present a low impedance return path for the self-coupled inductor noise on the differential signal line 20 from the net-port connector 30 (e.g., net-port RJ 45). When lightning stroke common mode energy is injected into the first input port 11 and the second input port 12 of the net mouth filter 10, a very large leakage current is generated at a center tap of the self-coupling inductor 110, the lightning stroke energy is mainly concentrated in a low frequency band (several MHz), and the self-coupling inductor 110 mainly discharges energy below the low frequency band (about 70% of the total energy of the lightning stroke common mode); and for the energy of the residual voltage of the frequency band above the low frequency band, after being suppressed by the common mode inductor 120, the energy is consumed on the common mode inductor 120 in a heat loss mode (about 20% of the total energy of the lightning stroke common mode), the common mode inductor 120 can suppress the energy of the lightning stroke residual voltage below 100MHz, and the energy of the lightning stroke residual voltage which is finally injected to a PHY (Port Physical Layer) chip is very weak after the remaining energy of the lightning stroke residual voltage above 100MHz is isolated by the isolation capacitor 131 and the isolation capacitor 132. It can be seen that in the present scheme, after the isolation capacitor 131 and the isolation capacitor 132 are disposed behind the common mode inductor 120, the requirement on the withstand voltage is not high, and 20V or less, for example, 16V, may be selected. Compared with the common mode inductor 120 before the isolation capacitor, the common mode inductor has the advantages of low cost, low voltage withstanding requirement, long service life and high safety and reliability. The isolation capacitor 131 and the isolation capacitor 132 in the scheme generally select a capacitor with a small size packaged by 0201 or 0402 to meet the design requirement, and the scheme has a great space advantage for products with very compact space.

Referring to fig. 2, a circuit diagram of a port filter 10 according to an embodiment of the present application only shows a portion related to the embodiment for convenience of description, and the detailed description is as follows:

the network port filter 10 comprises a first input port 11, a second input port 12, a first output port 13 and a second output port 14, in the same network port filter 10, a first differential link is arranged between the first input port 11 and the first output port 13, a second differential link is arranged between the second input port 12 and the second output port 14, a first coil 122 and a first isolation capacitor 131 are sequentially connected in series on the first differential link from the first input port 11, a second coil 124 and a second isolation capacitor 132 are sequentially connected in series on the second differential link from the second input port 11, wherein a third coil 114 and a fourth coil 116 form a self-coupling inductor 110, one end of the self-coupling inductor 110 is connected to the first input port 11, the other end of the self-coupling inductor is connected to the second input port 12, and a middle tap of the self-coupling inductor 110 is grounded; the first coil 122 and the second coil 124 form a common mode inductor 120, the first end of the third coil 114 is electrically connected to the first input port 11, the first end of the fourth coil 116 is electrically connected to the second input port 12, and the second end of the third coil 114 and the second end of the second coil 124 are center taps of the self-coupling inductor 110, which are used as ground pins 111 and 112 for grounding.

The self-coupled inductor 110 is used to discharge the instantaneous lightning strike energy, suppress EMI (Electromagnetic Interference), and suppress the Electromagnetic wave generated by the high-speed signal line from emitting outward radiation. The common mode inductor 120 is essentially a bi-directional filter: on one hand, common mode electromagnetic interference on a signal line is filtered, on the other hand, electromagnetic interference which is not emitted outwards is restrained, normal work of other electronic equipment under the same electromagnetic environment is prevented from being influenced, when a normal signal flows through the common mode inductor 120, the signal generates a reverse magnetic field in an inductance coil wound in the same phase and is mutually counteracted, at the moment, normal signal current is mainly influenced by coil resistance (and a small amount of damping caused by leakage inductance), when common mode noise flows through the coil, the same-direction magnetic field can be generated in the coil due to the same direction of the common mode current, so that the inductance of the coil is increased, the coil is enabled to be high-impedance, a strong damping effect is generated, the common mode current is attenuated, and the purpose of filtering is achieved. The isolation capacitor replaces the traditional network transformer, the square coupling signal of the electric field is adopted, the coupling effect is better than that of the traditional network transformer, the direct current component of the signal of the network is prevented from entering a post-stage circuit by utilizing the physical characteristic of blocking direct current and alternating current of the capacitor, in addition, the capacitance capacity can adjust the frequency low-frequency cut-off point of the signal passing through the network, the larger the capacitance capacity is, the lower the low-frequency cut-off point is, and more low-frequency noise can be coupled at the same time. Moreover, compared with the scheme of the traditional network transformer, the circuit board area can be greatly saved.

Referring to fig. 3, in a further embodiment, the network port filter 10 further includes a first bypass capacitor 161 and a second bypass capacitor 162, a first end of the first bypass capacitor 161 is electrically connected to the second end of the first isolation capacitor 131, a second end of the first bypass capacitor 161 is connected to the digital ground, a first end of the second bypass capacitor 162 is electrically connected to the second end of the second isolation capacitor 132, and a second end of the second bypass capacitor 162 is connected to the digital ground. The bypass capacitors 161, 162 are high frequency noise bypass capacitors, which are typically added on their own to suppress high frequency noise in the signal, depending on the EMI emission test. Optionally, the bypass capacitors 161, 162 are typically selected to be 10pF, and not more than 15pF at the highest, which would otherwise affect the eye diagram quality of the differential signal. Because the radiation suppression and the quality of the eye pattern of the differential signal are in a pair of contradictions, positions of bypass capacitors 161 and 162 can be reserved on a PCB, and the radiation test can pass a relevant test, so that the bypass capacitors 161 and 162 can be omitted, the eye pattern quality of the differential signal can be influenced, and the cost is reduced.

Referring to fig. 3, in a further embodiment, the mesh filter 10 further includes a first voltage dividing module 171 and a second voltage dividing module 172, wherein a second end of the first isolation capacitor 131 is electrically connected to the first output port 13 through the first voltage dividing module 171; a second end of the second isolation capacitor 132 is connected to the second output port 14 through the second voltage dividing module 172. Alternatively, the first voltage dividing module 171 and the second voltage dividing module 172 may be implemented by a series and parallel connection of resistors. The first voltage dividing module 171 and the second voltage dividing module 172 are both used as serial voltage dividing resistors, when a lightning signal is injected into the gateway filter 10, an instantaneous high voltage is discharged to the ground through the self-coupling inductor 110, but after part of noise is suppressed through the common mode inductor 120, the signals are coupled to the PHY chip through the isolation capacitors 131 and 132, and a small amount of residual voltage still exists, so that the residual voltage of the lightning can be divided by adding the serial voltage dividing resistors, and the influence on the PHY chip is reduced. In gigabit network products or equipment, a series voltage-dividing resistor is generally selected to be a resistor of 2.0 ohm or 2.2 ohm; in a hundred mega network product or device, a resistance of 5.1 ohms is typically selected. After voltage division is carried out by the series voltage dividing resistors, the residual voltage of lightning stroke can be restrained by about 5% -10% of the component. The series voltage dividing resistor is a resistor with 0402 packaging or packaging (such as 0603 packaging) above 0402, 0201 packaging and 01005 packaging are not recommended, the power of the series voltage dividing resistor meets the discharge requirement, and the packaging is too small and the power is insufficient.

In addition, in the self-coupled inductor 110 of a general network device, it includes a third coil 114 and a fourth coil 116, a first end of the third coil 114 is electrically connected to the first input port 11, a first end of the fourth coil 116 is electrically connected to the second input port 12, and a second end of the fourth coil 116 and a second end of the third coil 114 are middle taps of the self-coupled inductor 110, which are used as ground pins 111 and 112 to be grounded.

Referring to fig. 4 and 5, in the design of the circuit board of the network device, the differential signal lines in the self-coupled inductor 110 are designed according to the line width and line distance of the conventional differential signal lines, so as to avoid signal reflection caused by impedance abrupt change, and to make the tolerance of the pair length of the differential signal lines meet ± 5 mils. Referring to fig. 4, it should be noted that a pair of differential lines (i.e. a network port filter 10) corresponds to one self-coupled inductor 110, and the self-coupled inductors 110 are arranged in a straight line, so that the self-coupled inductors 110 of the pair of differential lines are not allowed to be close to the common-mode inductors 120 of the other pair of differential lines, which affects EMI and safety regulation. In addition, the plurality of self-coupled inductors 110 are arranged in a straight line, which facilitates SMT (Surface Mount Technology) component assembly. That is, on the circuit board, the self-coupled inductor 110 and the common-mode inductor 120 on the same differential signal line are arranged along the first direction Y1, and the isolation capacitor 131, the isolation capacitor 132, the voltage dividing resistor 171, and the voltage dividing resistor 172 on the same differential signal line are preferably arranged along the first direction Y1, like the self-coupled inductor 110 and the common-mode inductor 120.

Aiming at products with plastic shells such as a router, a gateway (such as a Bluetooth gateway), a set top box and the like, the commercial power input is two lines (including a live line and a zero line), and a ground wire is not arranged. Taking Wifi repeater as an example, referring to fig. 4, 5 and 6, the ground pins 111 and 112 of the self-coupled inductor 110 discharge the lightning strike energy to the negative electrode G of the primary side of the power circuit (e.g., AC-DC power circuit), the rectifying element 113, the commercial power network (live line or neutral line) through the negative electrode GND of the secondary side of the power circuit (e.g., AC-DC power circuit) and the Y capacitor 140, and finally to the ground through the far-end power transformer.

Referring to fig. 7 and 8, for products or devices with metal casings such as an exchange, etc., the commercial power input is three wires (including a ground wire, a live wire and a zero wire), the ground pins 111 and 112 of the self-coupling inductor 110 discharge the discharged lightning strike energy to the metal casing and the ground wire of the product or device through the discharging capacitor 141 and the TSS tube 150 (voltage switch type transient suppression diode) connected in parallel with the discharging capacitor 141, and then to the ground, and in more detail, the specific discharge path of the lightning strike energy of the products or devices with metal casings such as the exchange: floating ground → the discharge capacitor 141 and the TSS tube 150 connected in parallel with the discharge capacitor 141 → the metal screw hole 18 → the metal screw and the metal screw column → the metal case ground → the ground. Or, the ground pins 111 and 112 of the self-coupling inductor 110 discharge the discharged lightning strike energy to the metal casing and the ground wire of the product or equipment through the discharge capacitor 141 and the resistor connected in parallel with the discharge capacitor 141, and then to the ground; or, the ground pins 111 and 112 of the self-coupling inductor 110 discharge the discharged lightning strike energy to the metal casing and the ground wire of the product or equipment through the TSS tube 150 and then to the ground; alternatively, the ground pins 111, 112 of the self-coupled inductor 110 discharge the discharged lightning strike energy through the resistor to the metal case, ground, and then to ground of the product or device.

Referring to fig. 4 to 8, in a further embodiment, the self-coupled inductor 110 is disposed on a first outer layer (e.g. a top layer) of a circuit substrate (PCB) and electrically connected to any wiring layer (e.g. the top layer, the bottom layer or an intermediate layer) of the circuit substrate, and a conductor 16 for grounding is disposed on a second outer layer (e.g. the bottom layer) of the circuit substrate opposite to the first outer layer, the conductor 16 is directly opposite to the self-coupled inductor 110, and the ground pins 111 and 112 of the self-coupled inductor 110 are electrically connected to the conductor 16 through a ground via 15 disposed on the circuit substrate. In addition, the network product or device for a metal chassis such as a switchboard further includes a discharge capacitor 141 and a TSS tube 150, the electric conductor 16 is electrically connected to the screw hole pad 19 (connected to the metal chassis) through the discharge capacitor 141, and the TSS tube 150 is connected in parallel to the discharge capacitor 141, as shown in fig. 8.

Alternatively, the conductor 16 is a copper foil that is laid on the bottom layer of the circuit board, and has a long strip shape with a width of more than 20 mils, preferably 160 mils to 200 mils. For network products or devices with metal chassis such as switches, the ground vias 15 (floating ground) of the ground pins 111, 112 of all the self-coupled inductors 110 can be connected by the electrical conductor 16, and the electrical conductor 16 is connected in series with a TSS tube 150 and a discharge capacitor 140 to the screw pad 19 for discharging the lightning strike current from the differential signal line. If necessary, the copper foil as the conductor 16 can be exposed, and a steel mesh strip is added on the exposed copper (when SMT steel mesh brushing is performed, solder paste is printed on the exposed copper of the PCB, and when reflow soldering is performed, the solder paste is dissolved on the exposed copper to form a tin strip layer) so as to reduce the impedance of the copper foil, reduce the thermal resistance of the copper foil, quickly reduce the heat generated on the copper foil by lightning stroke, and avoid the lightning stroke and instantaneous current from burning off the wiring. In other embodiments, the electrical conductor 16 may be a strip or sheet of metal mounted on a circuit substrate.

A Wifi mainboard and an AC-DC power supply board in the Wifi repeater are combined in a plastic shell, and the mainboard and the AC-DC power supply board of products such as a router, a gateway (for example, a Bluetooth gateway) and a set top box are separated independently, and the common characteristics of the products are that the products are all products with plastic shells. Taking a Wifi repeater as an example (as shown in fig. 5, 6, 10), the secondary output power of the AC-DC power board 26 supplies power to the Wifi board through the pin header 23, wherein the ground pad 27 in the pin header 23 is connected to the electrical conductor 16. Lightning stroke energy (including lightning stroke voltage or lightning stroke current) from the network port connector 30 is discharged through the network port filter 10, then is injected into a negative pole GND of a secondary end of an AC-DC power supply board 26, a Y capacitor 140 and a negative pole G of a primary end of the AC-DC power supply board 26 through a hole 15, a conductive body 16 (copper foil) and a grounding bonding pad 27 of a pin header 23, and is discharged to a live wire and a zero wire in commercial power through a rectifying element 113 to a far-end power transformer and finally to the ground. And the edge spacing between each pad 110A used for welding the auto-coupling inductance 110 is more than 12 mils, preferably according to 20 mils to satisfy the production requirement, the distance between two auto-coupling inductance pads is too close, influences SMT to get and reprocess, avoids the crosstalk between the differential line differential signal line simultaneously.

As shown in fig. 5, the width of the trace path 18 electrically connecting the conductor 16 and the ground pad 27 of the pin header 23 on the circuit board is between 10mil and 30mil, preferably between 18mil and 20 mil; the distances between the pads of the ground pins 111 and 112 of the self-coupling inductor 110 and the edge of the ground via 15 are 1-10 mil, preferably 5-7 mil, respectively, and the design complies with the principle of "short" and "thick", so as to reduce the impedance of the discharge channel of the lightning strike current as much as possible.

In a network product or device, the common mode inductor 120 and the isolation capacitors 131, 132 are connected behind the self-coupling inductor 110, the common mode inductor 120 can suppress common mode noise from the network port connector 30, and the isolation capacitors 131, 132 can isolate low frequency noise from the network port connector 30. The self-coupling inductor 110, the common-mode inductor 120 and the isolation capacitors 131 and 132 form a three-stage protection and isolation network, and the residual voltage of a lightning stroke input into the PHY chip 40 is very low and basically within the allowable range of the PHY chip 40. Meanwhile, the self-coupling inductor 110, the common-mode inductor 120 and the isolation capacitors 131 and 132 form a three-stage protection, so that the network product or equipment is ensured to have a safety isolation function. In addition, in the design of the circuit substrate, the differential signal line from the self-coupled inductor 110 to the common-mode inductor 120 cannot be referenced to a ground plane; the self-coupled inductor 110 and the common-mode inductor 120 need to be arranged in order and on the same horizontal line. Isolating the differential lines of the capacitors 131, 132 to the common mode inductor 120, which cannot be referenced to the ground plane; the differential lines between the isolation capacitors 131 and 132 and the PHY chip 40 must be strictly controlled to have 100 ohms impedance to avoid impedance discontinuity reflection during signal transmission.

Fig. 5 shows the path of lightning current of the net gape filter 10 discharged on the Wifi repeater. Fig. 6 shows the path of lightning strike current bleeding at the AC-DC power panel 26. When the instantaneous lightning strike current is injected into the network port differential signal line 20, the self-coupling inductor 110 is quickly discharged onto the conductor 16 at the bottom layer, directly discharged onto the grounding bonding pad 27 of the pin header 23 through the short PCB copper foil routing path 18, quickly discharged onto the Y capacitor 140 of the AC-DC power supply board 26 through the pin header 23, then discharged onto the 220V commercial power, and finally discharged onto the ground.

During the design and structure of the PCB, it should be noted that the ground pad 27 of the pin header 23 is disposed as close to the net port filter 10 as possible, so as to reduce the impedance therebetween as much as possible, thereby providing a low impedance leakage path for the lightning current. In addition, the pin header 23 cannot be close to a sensitive device such as a Central Processing Unit (CPU), a Data Direction Register (DDR) or a Wifi chip between the net port filter 10, because there may be residual voltage near the net port filter 10, which may cause an abnormal function of the sensitive device.

In this example, the cross-sectional area of the conductor 16 on the surface of the bottom layer of the circuit board is as large as possible (≧ 20mil), so that the impedance of the copper foil on the back surface is reduced to the maximum extent, and lightning strike current on the differential signal line in the 4-to 96-channel switch can be discharged at the same time. If necessary, the copper foil on the back surface of the self-coupling inductor 110 can be exposed, and the copper is exposed on the copper foil to print a steel net, so that soldering tin is added to reduce impedance and reduce instant heat generated by lightning strike current. The net mouth filter 10 can bear lightning stroke of 1kV in differential mode and 4kV in common mode, and a TVS (Transient Voltage super) tube must be added if the differential mode is more than 1K.

Fig. 7 shows a layout wiring diagram of the gateway filter 10 on the circuit substrate of the switch in one embodiment. Figure 8 shows the top and bottom layout of the portal filter 10 on the circuit substrate of the switch in one embodiment. Fig. 9 shows wiring patterns of the differential signal lines between the gateway connector 30 and the gateway filter 10 in the same layer and adjacent layers of the circuit substrate in one embodiment, in which the black-filled wiring and the diagonal-filled wiring in fig. 9 are in different layers.

In the design of the main board of the switch, the ground pad 17 of the network connector 30 (connected to the housing of the network connector 30) and the screw hole pad 19 (connected to the chassis ground connector of the switch) are connected by copper foil, so as to reduce the impedance between the ground pad 17 of the network connector 30 and the chassis ground, and to contribute to lightning stroke protection, ESD discharge, and EMI suppression. The chassis ground of the switch is connected with the ground through the ground wire in the three power supply wires. It should be noted that: when the grounding pad 17 of the network port connector 30 is connected with the copper foil, attention should be paid to the design of the thermal pad to avoid the phenomenon that the heat dissipation is too fast to affect wave soldering.

The ground pad 17 and the screw pad 19 of the network port connector 30 and the copper foil therebetween are maintained at a safe distance L1 of at least 1mm (1mm ≈ 39.37mil) from the differential signal line 20 in the network port connector 30; in addition, signals (such as indicator lights and switch signals of a panel) from copper foil between the housing ground pin 17 and the screw hole pad 19 of the network connector 30 to a digital ground and other networks keep a safety distance L2 of at least 1 mm.

It should be noted that the differential signal line 20 from the network port connector 30 to the network port filter 10 cannot be referenced to a ground plane (e.g., digital ground, chassis ground). The difference signal line 20 between the network port connector 30 and the network port filter 10 reduces the layer change of the signals as much as possible, if the signals are crossed and blocked, the layer change is needed, the layer change frequency of each difference signal line 20 cannot exceed 2 through holes, so that the impedance jump of the signals on the through holes is reduced, and the quality of the eye diagram is influenced. The differential signal line 20 from the gateway connector 30 to the gateway filter 10 has no reference plane, so that the differential signal line 20 at this stage is undesirably connected via holes to provide a return current during layer change.

In the differential signal lines 20 from the network port connector 30 to the network port filter 10, the pitch L3 between the differential signal lines 20 having the same routing direction (i.e., parallel routing lines) in the same layer is maintained at ≧ 10mil, so as to avoid crosstalk between the signals. If the distance L3 between the parallel differential signal lines 20 of the same layer is between 15mil and 20mil, the length H1 of the parallel differential signal line segments is controlled within 200mil, and if the distance L3 between the parallel differential signal lines 20 of the same layer is between 13mil, the length H1 of the parallel differential signal line segments is controlled within 100mil and 150 mil.

Two adjacent differential signal lines 20 are distributed between the gateway connector 30 and the gateway filter 10, and the vertical projections of two adjacent differential signal lines 20 with the same wiring direction are not overlapped. For example, the distance L4 between the vertical projections of the differential signal lines 20 with parallel tracks of adjacent layers on the same layer is maintained to be ≧ 5mil, and the length H2 of the differential signal line segment with parallel tracks is controlled to be within 40 mil; the distance L4 between the vertical projections of the differential signal lines 20 with the parallel adjacent tracks on the same layer is kept equal to or larger than 10 mils, and the length H2 of the differential signal line segment with the parallel tracks is controlled within 200 mils; the distance L4 between the vertical projections of the differential signal lines 20 with the parallel adjacent tracks on the same layer is kept equal to or larger than 15 mils, and the length H2 of the differential signal line segment with the parallel tracks is controlled within 300 mils, so that crosstalk between signals is avoided. Overlap between adjacent two differential signal lines 20 is inhibited.

For a switch with a large size (e.g. a 24-way switch), the line width, line distance, and stacking arrangement of each pair of differential signal lines 20 between the network port connector 30 and the network port filter 10 must satisfy the requirement of differential signal impedance (e.g. 100 ohms), and in addition, the minimum line width of the differential signal lines 20 must not be less than 2.5mil (preferably ≧ 4mil), otherwise, the routing is too long, the skin loss is very large, and the quality of the eye diagram is affected.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.