WO2020116055A1

WO2020116055A1 - Noise filter and network connection device

Info

Publication number: WO2020116055A1
Application number: PCT/JP2019/042556
Authority: WO
Inventors: 太郎樋口; 由浩今西; 峰日登吉田; 康誌齋藤; 佳惠中村; 紗弥佳関口; みゆき野尻
Original assignee: 株式会社村田製作所
Priority date: 2018-12-03
Filing date: 2019-10-30
Publication date: 2020-06-11
Also published as: JP7115564B2; JPWO2020116055A1

Abstract

A first core and a second core are arranged with an interval therebetween. Two end part magnetic members made of a magnetic material connect one end parts of the first core and the second core to each other, and connect the other end parts to each other. Two first winding wires are wound around the first core and constitute a common mode choke coil. Two second winding wires are wound in reverse directions to each other over the first core and the second core, and the two coils constituted of the two second winding wires have an open magnetic path structure.

Description

Noise filter and network connection device

The present invention relates to a noise filter and a network connection device.

A circuit for transmitting and receiving a differential signal and supplying power by superimposing a DC current on the differential signal line is known. A common mode choke coil is inserted in the differential signal line to prevent leakage of common mode noise to a cable that transmits differential signals. In order to suppress the conduction of high frequency signals from the differential signal line to the power supply, an inductor (differential mode inductor) that has a high impedance to the differential mode signal is inserted in the power supply line that connects the differential signal line and the power supply. To be done.

In order to enhance the effect of suppressing common mode noise, a common mode choke coil may be inserted in series in the differential signal line, and a circuit may be provided to ground each differential signal line via an inductor and a capacitor.

 It is desirable to integrate the common mode choke coil and the differential mode inductor in order to suppress the increase in the number of parts and the mounting area.

Patent Document 1 below discloses a coil component that constitutes a circuit in which a common mode choke coil and a normal mode (differential mode) choke coil are connected in series. This coil component includes a first magnetic core forming a closed magnetic circuit and a second magnetic core forming a closed magnetic circuit having a shape that fits inside the first magnetic core. Each of the first winding and the second winding is wound around both the first magnetic core and the second magnetic core in one part, and is wound around the first magnetic core only in the other part. The portion wound around the first magnetic core has opposite winding directions between the first winding and the second winding, and the portion wound around the second magnetic core has the first winding and the second winding. The winding direction is the same as the winding.

JP, 09-148144, A

In the coil component disclosed in Patent Document 1, two windings form both a common mode choke coil and a differential mode choke coil. That is, this coil component is a four-terminal circuit in which a common mode choke coil and a differential mode choke coil are connected in series. For this reason, this coil component is used for the purpose of directly inserting the common mode choke coil into the differential signal line and connecting the differential signal line to the inductor power supply and ground via the differential mode choke coil (differential mode inductor). It cannot be used.

The object of the present invention is to provide a noise filter that integrates a common mode choke coil that is inserted into a differential signal line and a differential mode inductor that connects the differential signal line to a power supply or ground. Another object of the present invention is to provide a network connection device equipped with this noise filter.

According to one aspect of the invention,
A first core and a second core that are arranged so as to be adjacent to each other at a distance;
Two end magnetic members made of a magnetic material, which connect one ends of the first core and the second core to each other and connect the other ends of the first core and the second core,
Two first windings wound around the first core to form a common mode choke coil;
The first core and the second core are provided with two second windings wound in opposite directions, and the two coils formed of the two second windings are open magnetic circuits. A noise filter having a structure is provided.

According to another aspect of the invention,
Board,
An integrated circuit device mounted on the substrate,
A connector mounted on the board and connected to an external device,
Two signal lines formed on the substrate and connecting the integrated circuit element and the connector;
And a noise filter mounted on the substrate,
The noise filter is
A first core and a second core that are arranged so as to be adjacent to each other at a distance;
Two end magnetic members made of a magnetic material, which connect one ends of the first core and the second core to each other and connect the other ends of the first core and the second core,
Two first windings wound around the first core to form a common mode choke coil;
The first core and the second core are provided with two second windings wound in opposite directions, and the two coils formed of the two second windings are open magnetic circuits. Have a structure,
A common mode choke coil composed of the first winding is inserted in series with the two signal lines, and one end of each of the two second windings is connected to each of the two signal lines. A network connection device is provided.

A noise filter that integrates a common mode choke coil consisting of two first windings and another two coils consisting of two second windings can be obtained. It is possible to insert the common mode choke coil in series with the signal line and connect the signal line to the power supply or the ground via the two coils composed of the two second windings.

1A, 1B, and 1C are a front view, a bottom view, and a side view, respectively, of a noise filter according to the first embodiment. FIG. 2 is a schematic equivalent circuit diagram of the network connection device equipped with the noise filter according to the first embodiment. FIG. 3 is a side view of the noise filter according to the first embodiment. FIG. 4A is a diagram showing a connection configuration of an evaluation experiment for measuring an S parameter using a network analyzer, and FIG. 4B is a front view of a noise filter according to a comparative example. FIG. 5 is a graph showing the measurement results of the transmission coefficient Scc21. FIG. 6 is a schematic equivalent circuit diagram of the network connection device according to the second embodiment. FIG. 7 is a front view of the noise filter according to the third embodiment. FIG. 8 is a schematic diagram of a vehicle equipped with the network connection device according to the fourth embodiment.

[First embodiment]
A noise filter and a network connection device according to a first embodiment will be described with reference to FIGS. 1 to 5.

1A, 1B, and 1C are a front view, a bottom view, and a side view, respectively, of the noise filter according to the first embodiment. The noise filter 10 according to the first embodiment is generally used in a form mounted on the surface of a printed circuit board or the like. The surface of the noise filter 10 that faces the printed circuit board is defined as the “bottom surface”, the surface that faces the opposite direction to the bottom surface is defined as the “top surface”, and the surface that faces the direction substantially parallel to the surface of the printed circuit board is defined as the “top surface”. Side. The noise filter 10 includes a support 20, two first windings 16 and two second windings 17.

The support 20 includes a first core 21, a first end magnetic member 22, a second end magnetic member 23, a second core 25, a first electrode pair 11, a second electrode pair 12, and a third electrode pair 13. Including. The first core 21, the first end magnetic member 22, the second end magnetic member 23, and the second core 25 are made of a magnetic material such as Ni—Zn ferrite. The 1st core 21 and the 2nd core 25 are arranged so that it may line up at intervals, and the 1st end magnetic member 22 connects one end of the 1st core 21 and the 2nd core 25, The second end magnetic member 23 connects the other ends of the first core 21 and the second core 25. The first core 21 has, for example, a rectangular columnar or columnar outer shape. The second end magnetic member 23 includes an end plate 23A continuous with the end of the first core 21, and side plates 23B extending from both ends of the end plate toward the first end magnetic member 22 in plan view. .

The first electrode pair 11 is provided on the bottom surface of the first end magnetic member 22. The two electrodes of the first electrode pair 11 are arranged on both sides of the first core 21 in plan view. The second electrode pair 12 and the third electrode pair 13 are provided on the bottom surface of the second end magnetic member 23. The two electrodes of the third electrode pair 13 are respectively disposed on the bottom surface of the end plate 23A and on both sides of the first core 21 in plan view. The two electrodes of the second electrode pair 12 are respectively arranged at the tips of the bottom surfaces of the two side plates 23B.

The first electrode pair 11, the second electrode pair 12, and the third electrode pair 13 are arranged at different positions in the axial direction of the first core 21, and the first core 21 moves from one end to the other end of the first core 21. The electrode pair 11, the second electrode pair 12, and the third electrode pair 13 are arranged in this order. In addition, the first electrode pair 11, the second electrode pair 12, and the third electrode pair 13 are arranged in a total of six electrodes on one virtual plane for surface mounting.

The second core 25 is composed of a top plate that extends from the upper surface of the first end magnetic member 22 to the upper surface of the second end magnetic member 23. A closed magnetic circuit is formed by the first core 21, the first end magnetic member 22, the second core 25, and the second end magnetic member 23.

The two first windings 16 are wound around the first core 21 in the same winding direction. The two first windings 16 function as a common mode choke coil having a high impedance with respect to common mode noise. This common mode choke coil has a closed magnetic circuit structure. The two second windings 17 are wound over the first core 21 and the second core 25 so that the winding directions are opposite to each other. The two second windings 17 have low impedance with respect to common mode noise and high impedance with respect to differential mode signals. In this specification, such an inductor is referred to as a "differential mode inductor". This differential mode inductor has an open magnetic circuit structure. In the drawings from FIG. 1A to FIG. 1C, the two first windings 16 and the two second windings 17 are shown with a number smaller than the actual number of windings so that the winding direction can be easily understood.

One end of each of the two first windings 16 is connected to each electrode of the first electrode pair 11, and the other end is connected to each electrode of the second electrode pair 12. One end of each of the two second windings 17 is connected to each electrode of the first electrode pair 11, and the other end is connected to each electrode of the third electrode pair 13. Each of the two first windings 16 is connected to the electrodes on the same side with respect to the first core 21 in plan view. Similarly, each of the two second windings 17 is connected to the electrodes on the same side with respect to the first core 21 in plan view.

FIG. 2 is a schematic equivalent circuit diagram of a network connection device equipped with the noise filter 10 according to the first embodiment. The noise filter 10, the integrated circuit element (IC) 31, the connector 32, and the two capacitors 35 are mounted on the substrate 30. Further, the substrate 30 is provided with two signal lines 37 for transmitting differential signals and a ground conductor 38. A cable 40 for transmitting/receiving a signal to/from an external device is connected to the connector 32.

The two signal lines 37 connect the IC 31 and the connector 32. The noise filter 10 is inserted into the two signal lines 37 so that the first electrode pair 11 of the noise filter 10 is connected to the IC 31 and the second electrode pair 12 is connected to the connector 32. The third electrode pair 13 of the noise filter 10 is connected to the ground conductor 38 via the capacitors 35, respectively.

The two first windings 16 of the noise filter 10 form a common mode choke coil 18, and the two second windings 17 form a differential mode inductor 19. The common mode choke coil 18 is inserted in series with the two signal lines 37. The two signal lines 37 are grounded between the IC 31 and the common mode choke coil 18 via the differential mode inductor 19 and the capacitor 35.

Next, the excellent effect of the first embodiment will be described with reference to FIG.
In the first embodiment, the common mode choke coil 18 suppresses common mode noise leaking from the signal line 37 to the cable 40. Further, the common mode noise generated on the signal line 37 flows into the ground conductor 38 via the differential mode inductor 19. Therefore, the effect of suppressing common mode noise can be enhanced. Since the common mode choke coil 18 and the differential mode inductor 19 are provided on the common support 20, it is possible to reduce the number of parts.

The capacitor 35 prevents a direct current flowing through the ground conductor 38 from flowing into the signal line 37.

FIG. 3 is a front view of the noise filter 10 according to the first embodiment, in which the magnetic flux 51 generated by the first winding 16 and the magnetic flux 52 generated by the second winding 17 are schematically shown. Has been done.

Most of the magnetic flux 51 generated by the current flowing through the first winding 16 is in the closed magnetic circuit formed by the first core 21, the first end magnetic member 22, the second core 25, and the second end magnetic member 23. Be trapped. The direction of the magnetic flux 51 in the first core 21 and the direction of the magnetic flux 51 in the second core 25 are opposite to each other. For example, when the magnetic flux 51 in the first core 21 is directed from the second end magnetic member 23 to the first end magnetic member 22, the magnetic flux 51 in the second core 25, on the contrary, is the first end magnetic member. The second end magnetic member 23 faces from 22. Therefore, the second winding wire 17 wound around the first core 21 and the second core 25 does not interlink with the magnetic flux 51. As a result, the influence of the current flowing through the first winding 16 on the second winding 17 is reduced.

The magnetic flux 52 generated by the current flowing through the second winding 17 has the same direction inside the first core 21 and inside the second core 25. Therefore, the coil including the two second windings 17 has the disclosed path structure. That is, the magnetic flux 52 includes the leakage magnetic flux leaked from the support 20 made of a magnetic material. In the configuration in which the second winding wire 17 is wound only around the first core 21 like the first winding wire 16, most components of the magnetic flux generated by the current flowing through the second winding wire 17 interlink with the first winding wire 16. To do. On the other hand, in the first embodiment, of the magnetic flux 52 generated by the current flowing through the second winding 17, only the magnetic flux 52 in the first core 21 is linked to the first winding 16 and the second core 25 The magnetic flux 52 therein does not interlink with the first winding 16. That is, only a part of the magnetic flux 52 generated by the current flowing through the second winding 17 is linked to the first winding 16. Therefore, the influence of the current flowing through the second winding 17 on the first winding 16 is reduced.

In order to confirm the excellent effect of the first embodiment, an evaluation experiment was conducted on the noise filter 10 according to the first embodiment and the noise filter according to the comparative example. Next, this evaluation experiment will be described with reference to FIGS. 4A to 5.

FIG. 4A is a diagram showing a connection configuration for measuring the S parameter of the noise filter using the network analyzer 60. The two electrodes of the first electrode pair 11 of the noise filter 10 are connected to the ports P1 and P3 of the network analyzer 60, respectively, and the two electrodes of the second electrode pair 12 are connected to the ports P2 and P4 of the network analyzer 60, respectively. did. Two electrodes of the third electrode pair 13 of the noise filter 10 were grounded. With this connection configuration, the transmission coefficient Scc21 of the common mode component from the first electrode pair 11 to the second electrode pair 12 was measured.

In this connection, the common mode choke coil 18 suppresses the leakage of the common mode component to the second electrode pair 12, and the differential mode inductor 19 causes the common mode component to flow to the ground. Therefore, it can be said that the smaller the transmission coefficient Scc21, the more effectively the common mode choke coil 18 and the differential mode inductor 19 function.

FIG. 4B is a front view of the noise filter according to the comparative example. In the comparative example, the first winding 16 and the second winding 17 are both wound around the first core 21. The other structure is the same as that of the noise filter 10 according to the first embodiment.

FIG. 5 is a graph showing the measurement results of the transmission coefficient Scc21. The horizontal axis represents the frequency in the unit of "MHz", and the vertical axis represents the transmission coefficient Scc21 in the unit of "dB". A solid line and a broken line in the graph of FIG. 5 show the measurement results of the noise filter 10 according to the first example and the noise filter according to the comparative example (FIG. 4B), respectively. It can be seen that the transmission coefficient Scc21 of the noise filter 10 according to the first example is smaller than the transmission coefficient Scc21 of the noise filter according to the comparative example. That is, in the noise filter 10 according to the first example, the common mode choke coil 18 and the differential mode inductor 19 function more effectively than the noise filter according to the comparative example. This can be said to be the effect of adopting the configuration in which the second winding 17 is wound over the first core 21 and the second core 25 in the noise filter 10 according to the first embodiment.

From this evaluation experiment, it was confirmed that the noise suppressing effect can be enhanced by suppressing the magnetic coupling between the common mode choke coil 18 (FIG. 2) and the differential mode inductor 19 (FIG. 2) in the first embodiment. It was

Furthermore, in the first embodiment, since the top plate of the support 20 (FIG. 1A) is used as the second core 25, the excellent effect that the component size does not increase even if the second core 25 is provided can be obtained. ..

Next, a modification of the first embodiment will be described.
In the first embodiment, as shown in FIG. 1B, the first winding 16 forming the common mode choke coil 18 is connected between the first electrode pair 11 and the second electrode pair 12, and the differential mode inductor 19 is connected. The second winding wire 17 constituting the above is connected between the first electrode pair 11 and the third electrode pair 13. As another configuration, the first winding 16 is connected between the first electrode pair 11 and the third electrode pair 13, and the second winding 17 is connected between the first electrode pair 11 and the second electrode pair 12. You may connect.

[Second Embodiment]
Next, a network connection device according to the second embodiment will be described with reference to FIG. Hereinafter, the description of the same configuration as that of the network connection device (FIG. 2) using the noise filter 10 according to the first embodiment will be omitted.

FIG. 6 is a schematic equivalent circuit diagram of the network connection device according to the second embodiment. In the network connection device (FIG. 2) according to the first embodiment, the two electrodes of the third electrode pair 13 of the noise filter 10 are grounded via the capacitors 35, respectively. On the other hand, in the second embodiment, the two electrodes of the third electrode pair 13 of the noise filter 10 are connected to the two power supply lines 33 provided on the substrate 30, respectively. The power supply line 33 is connected to an external DC power supply 41 via a power supply terminal 39.

Capacitors 34 are inserted in series in the two signal lines 37 between the noise filter 10 and the IC 31.

In the second embodiment, the DC power supplied from the DC power supply 41 to the substrate 30 is supplied to the external device through the power supply line 33, the signal line 37, the connector 32, and the cable 40. Adopting a configuration in which the power supply line 33 is not connected to the external DC power supply 41 and DC power is supplied from the external device to which the cable 40 is connected to the power supply line 33 via the cable 40, the connector 32, and the signal line 37. Is also possible.

Next, the excellent effect of the second embodiment will be described.
Also in the second embodiment, the common mode choke coil 18 suppresses the leakage of common mode noise from the signal line 37 to the cable 40. The differential mode inductor 19 suppresses the high frequency signal transmitted through the signal line 37 from flowing into the power supply line 33. Thereby, it is possible to suppress the disturbance of the signal waveform of the high frequency signal transmitted through the signal line 37. The capacitor 34 disconnects the IC 31 from the power supply line 33 in a direct current manner.

Since the noise filter 10 according to the first embodiment (FIGS. 1A, 1B, and 1C) is used as the noise filter 10, magnetic coupling between the common mode choke coil 18 and the differential mode inductor 19 is reduced, and Can function effectively.

[Third Embodiment]
Next, the noise filter 10 according to the third embodiment will be described with reference to FIG. Hereinafter, description of the configuration common to the noise filter 10 (FIGS. 1A, 1B and 1C) according to the first embodiment will be omitted.

FIG. 7 is a front view of the noise filter 10 according to the third embodiment. In the first embodiment, the two first windings 16 (FIG. 1A) are wound only around the first core 21. On the other hand, in the third embodiment, a part of each of the two first windings 16 is wound around the first core 21, and the remaining part is wound around the second core 25. When an electric current is applied to the first winding 16, the winding direction of the portion wound around the first core 21 and the portion wound around the second core 25 generate a magnetic flux in the same direction in the closed magnetic circuit. Is set. The two second windings 17 are wound over the first core 21 and the second core 25 so that the winding directions are opposite to each other, as in the first embodiment.

Next, the excellent effect of the third embodiment will be described.
Also in the third embodiment, most components of the magnetic flux 51 generated by the current flowing through the two first windings 16 do not interlink with the second winding 17. Therefore, similarly to the first embodiment, the influence of the current flowing through the first winding 16 on the second winding 17 is reduced.

The magnetic flux 52 generated by the current flowing through the two second windings 17 interlinks with the portion of the first winding 16 that is wound around the first core 21, and also with the portion that is wound around the second core 25. Interlink. When viewed from the first winding 16, the magnetic flux 52 interlinking with the portion wound around the first core 21 and the magnetic flux 52 interlinking with the portion wound around the second core 25 have a relationship of canceling each other out. is there. Therefore, the magnetic flux 52 generated by the current flowing through the second winding 17 has a smaller amount of components interlinking with the first winding 16 than in the case of the first embodiment. Therefore, the influence of the current flowing through the second winding 17 on the first winding 16 is reduced.

As described above, in the third embodiment, the effect of suppressing the magnetic coupling between the common mode choke coil 18 and the differential mode inductor 19 (FIGS. 2 and 6) is greater than that in the first embodiment. As a result, the characteristics relating to noise suppression are further improved.

[Fourth Embodiment]
Next, a network connection device according to the fourth embodiment will be described with reference to FIG. Hereinafter, description of the configuration common to the noise filter and the network connection device according to each of the first to third embodiments will be omitted.

FIG. 8 is a schematic diagram of a vehicle 75 equipped with the network connection device 70 according to the fourth embodiment. The network connection device 70 mounted on the vehicle 75 is equipped with the noise filter 10 according to any one of the first to third embodiments. The vehicle 75 is further equipped with a DC power supply 41 and an in-vehicle device 72.

DC power is supplied from the DC power supply 41 to the network connection device 70. The network connection device 70 and the in-vehicle device 72 are connected by the cable 40. A differential signal is transmitted between the network connection device 70 and the in-vehicle device 72 via the cable 40. Further, DC power is supplied from the DC power supply 41 to the vehicle-mounted device 72 via the network connection device 70 and the cable 40.

Since the noise filter 10 according to any one of the first to third embodiments is mounted on the network connection device 70 according to the fourth embodiment, noise suppression, device miniaturization, and parts are achieved. It is possible to reduce the number of points.

Needless to say, each of the above-described embodiments is an example, and partial replacement or combination of the configurations shown in different embodiments is possible. The same effects by the same configurations of the plurality of embodiments will not be sequentially described for each embodiment. Furthermore, the invention is not limited to the embodiments described above. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

10 Noise Filter 11 First Electrode Pair 12 Second Electrode Pair 13 Third Electrode Pair 16 First Winding 17 Second Winding 18 Common Mode Choke Coil 19 Differential Mode Inductor 20 Support 21 Core 22 First End Magnetic Member 23 Second end magnetic member

23A End plate

23B Side plate 25 Second core 30 Substrate 31 Integrated circuit element (IC)
32 connector 33 power supply line 34, 35 capacitor 37 signal line 38 ground conductor 39 power supply terminal 40 cable 41 DC power supply 51 magnetic flux generated by the first winding 52 magnetic flux generated by the second winding 60 network analyzer 70 network connection device 72 vehicle-mounted Equipment 75 vehicle

Claims

A first core and a second core that are spaced apart;
Two end magnetic members made of a magnetic material, which connect one ends of the first core and the second core to each other, and connect the other ends of the first core and the second core,
Two first windings wound around the first core to form a common mode choke coil;
The first core and the second core are provided with two second windings wound in opposite directions, and the two coils formed of the two second windings are open magnetic circuits. A noise filter having a structure.
The noise filter according to claim 1, wherein the two first windings are not wound around the second core.
The two first windings are also wound around the second core, and a portion of the two first windings wound around the first core and a portion wound around the second core. The noise filter according to claim 1, wherein the portion and the portion are wound in a closed magnetic circuit formed of the first core, the second core, and the end magnetic member so as to generate magnetic flux in the same direction.
Board,
An integrated circuit device mounted on the substrate,
A connector mounted on the board and connected to an external device,
Two signal lines formed on the substrate and connecting the integrated circuit element and the connector;
And a noise filter mounted on the substrate,
The noise filter is
A first core and a second core that are spaced apart;
Two end magnetic members made of a magnetic material, which connect one ends of the first core and the second core to each other and connect the other ends of the first core and the second core,
Two first windings wound around the first core to form a common mode choke coil;
The first core and the second core are provided with two second windings wound in opposite directions, and the two coils formed of the two second windings are open magnetic circuits. Have a structure,
A common mode choke coil composed of the first winding is inserted in series with the two signal lines, and one end of each of the two second windings is connected to each of the two signal lines. Network connection device.
A power line is provided on the substrate,
The network connection device according to claim 4, wherein the other ends of the two windings are connected to the power supply line, respectively.
The network connection device according to claim 4, wherein the other ends of the two windings are grounded via capacitors, respectively.
7. The network connection device according to claim 4, wherein the connector is connected to an in-vehicle device via a cable.