Common Mode Filters and Terminal Devices

Abstract

The present application relates to a common mode filter and a terminal device. The common mode filter includes a first coil group, a second coil group, and a third coil group, which are parallel to each other and arranged consecutively: a first magnetic layer, a first coil layer, one or more intermediate coil layers, a second coil layer, and a second magnetic layer. The first coil group includes a first cable in each coil layer. The second coil group includes a second cable in each coil layer. The third coil group includes a third cable in each coil layer. The cables in each coil group are connected to each other through cable holes in the coil group, and at least two of the multiple cables in the same coil layer are wound in parallel. According to the common mode filter and terminal device provided in the embodiment of the present application, the distances from all coil groups of the common mode filter to the first magnetic layer and the second magnetic layer are matched and in phase, resulting in improved symmetry between different coil groups and reduced longitudinal transmission loss of the common mode filter.

Description

[Technical field]

[0001] The present application relates to the field of electronic technology, and in particular to common mode filters and terminal devices. [Background technology]

[0002] This application claims priority to Chinese Patent Application No. 202011311813.4, entitled “COMMON-MODE FILTER AND TERMINAL DEVICE,” filed with the State Intellectual Property Office of the People's Republic of China on November 20, 2020, which is incorporated herein by reference in its entirety.

[0003] As terminal products such as mobile phones, smart tablets, and portable computers become smaller and thinner, the spatial distance from the radio frequency antenna to the high-speed data transmission interface (e.g., Mobile Industry Processor Interface, abbreviated as MIPI) used in the multimedia system, such as the camera or display, the SerDes (abbreviation of SERializer / DESerializer) interface, or the transmission interface supporting embedded digital audio and video (Embedded Display Port, abbreviated as eDP) becomes smaller and smaller, and the coupling between the radio frequency antenna and the interface becomes stronger. As a result, high-speed data transmission methods such as MIPI cause greater interference to the radio frequency system and are more likely to be affected by the radio frequency transmission power. This becomes an important factor affecting the electromagnetic compatibility between the radio frequency on the terminal product such as the mobile phone and the multimedia system. In order to solve the problem of coexistence between radio frequencies and high-speed differential data transmission modules, such as MIPI, SerDes, and eDP, a common mode filter with high common mode suppression, low longitudinal transmission loss, and good symmetry is required, which solves the problem that the common mode filter in the related technology has insufficient symmetry and is easy to convert common mode noise into differential mode noise, which reduces the filtering effect of the common mode filter against common mode interference noise. Summary of the Invention

[0004] In view of this, a common mode filter with high symmetry and low longitudinal transmission loss and a terminal device are proposed.

[0005] According to a first aspect, an embodiment of the present application provides a common mode filter. The common mode filter includes a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, and a plurality of coil layers parallel to each other. The plurality of coil groups includes at least a first coil group, a second coil group, and a third coil group, the plurality of cable holes includes at least a first cable hole, a second cable hole, and a third cable hole, the plurality of coil layers includes a first coil layer, at least one intermediate coil layer, and a second coil layer, and at least a first cable, a second cable, and a third cable are disposed in each coil layer. The first coil layer, the intermediate coil layer, and the second coil layer are stacked in succession between the first magnetic layer and the second magnetic layer. The first coil group includes a first cable in each coil layer, the second coil group includes a second cable in each coil layer, and the third coil group includes a third cable in each coil layer. The first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group. At least two of the first cables, the second cables, and the third cables in the same coil layer are wound in parallel. In this way, the distances from all the coil groups to the first magnetic layer and the second magnetic layer are matched in phase, which improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0006] According to a second aspect, an embodiment of the present application provides a common mode filter. The common mode filter includes a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, and a plurality of coil layers parallel to each other. The plurality of coil groups includes at least a first coil group, a second coil group, and a third coil group, the plurality of cable holes includes at least a first cable hole, a second cable hole, and a third cable hole, the plurality of coil layers includes a first coil layer, at least one intermediate coil layer, and a second coil layer, and at least a first cable, a second cable, and a third cable are disposed in each coil layer. The first coil layer, the intermediate coil layer, and the second coil layer are disposed successively between the first magnetic layer and the second magnetic layer. The first coil group includes a first cable in each coil layer, the second coil group includes a second cable in each coil layer, and the third coil group includes a third cable in each coil layer. The first cable hole is configured to connect a plurality of first cables of a first coil group, the second cable hole is configured to connect a plurality of second cables of a second coil group, and the third cable hole is configured to connect a plurality of third cables of a third coil group. At least two of the first cables, the second cables, and the third cables in the same coil layer are wound in parallel, and the cable widths of the same coil group satisfy one of the following: the width of the first cable and the width of the second cable are each the first cable width, the width of the third cable is the second cable width, and the first cable width is different from the second cable width; or the width of the first cable, the second cable width, and the width of the third cable are all different, and the width of the first cable is the first cable width, and the width of the second cable is the second cable width. The first cable width and the second cable width satisfy W1=p1×W2, where W1 is the first cable width, W2 is the second cable width, p1 is a ratio coefficient, and p1∈[0.5, 0.8] or p1∈[2, 3].

[0007] According to the above arrangement, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase with each other, so that the symmetry between different coil groups is improved and the longitudinal transmission loss of the common mode filter is reduced. In addition, the cable width of each coil group is set based on a preset width ratio relationship, so that the impedance difference caused by the different total lengths of the cables in different coil groups, the different cable thicknesses of different coil groups caused by processing techniques, and the non-matching phases of the cables in different coil groups caused by the position settings of the cable holes can be further improved. The cable widths of different coil groups can be adjusted by adjusting the width ratio relationship, so that the different coil groups have similar or the same characteristic impedance, so that the symmetry between different coil groups is improved and the longitudinal transmission loss of the common mode filter is reduced.

[0008] According to the first and second aspects, in a first possible implementation of the common mode filter, there is a first relative positional relationship between the first cable, the second cable, and the third cable in the first coil layer, there is a second relative positional relationship between the first cable, the second cable, and the third cable in the second coil layer, and there is an intermediate relative positional relationship between the first cable, the second cable, and the third cable in the intermediate coil layer. The first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same, and the centerlines of the first cable hole for connecting the first cable in the adjacent coil layer, the second cable hole for connecting the second cable in the adjacent coil layer, and the third cable hole for connecting the third cable in the adjacent coil layer are all located on the same cross section perpendicular to all coil layers. In this way, the distances from all coil groups to the first magnetic layer and the second magnetic layer are consistent and in phase, and in each coil layer, the relative positional relationships between the cables of different coil groups are the same, thereby further improving the symmetry between different coil groups and further reducing the longitudinal transmission loss of the common mode filter.

[0009] According to the first and second aspects, in a second possible implementation of the common mode filter, there is a first relative positional relationship between the first cable, the second cable, and the third cable in the first coil layer, there is a second relative positional relationship between the first cable, the second cable, and the third cable in the second coil layer, and there is an intermediate relative positional relationship between the first cable, the second cable, and the third cable in the intermediate coil layer. The first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are different, and the first total length of the first cables of the first coil group, the second total length of the second cables of the second coil group, and the third total length of the third cables of the third coil group are the same. In this way, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase and matched. In addition, the relative positional relationship between the cables of different coil groups in each coil layer is changed, so that the total length of the cables of different coil groups is the same, which further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0010] According to the first and second aspects, in a third possible implementation of the common mode filter, there is a first relative positional relationship between the first cable, the second cable, and the third cable in the first coil layer, there is a second relative positional relationship between the first cable, the second cable, and the third cable in the second coil layer, and there is an intermediate relative positional relationship between the first cable, the second cable, and the third cable in the intermediate coil layer. The first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same, and the first total length of the first cables of the first coil group, the second total length of the second cables of the second coil group, and the third total length of the third cables of the third coil group are the same. In this way, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase and matched. In addition, based on the same relative positional relationship between the cables of different coil groups in each coil layer, the lengths of the cables in different coil layers are changed, so that the total lengths of the cables of different coil groups are the same, which further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0011] According to the first aspect, the second aspect, the first possible implementation, the second possible implementation, or the third possible implementation, in a fourth possible implementation of the common mode filter, the common mode filter further includes a reference ground structure, the reference ground structure being isolated from all of the first cables, all of the second cables, and all of the third cables, and the reference ground structure being isolated from both the first magnetic layer and the second magnetic layer.

[0012] According to the fourth possible implementation, in a fifth possible implementation of the common mode filter, the reference ground structure includes a first auxiliary layer and a second auxiliary layer.

[0013] The first auxiliary layer is located between the first coil layer and the first magnetic layer, and a first reference ground cable corresponding to the first cable, the second cable, and the third cable in the first coil layer is disposed in the first auxiliary layer.

[0014] The second auxiliary layer is located between the second coil layer and the second magnetic layer, and the second reference ground cable corresponding to the first cable, the second cable, and the third cable in the second coil layer is arranged in the second auxiliary layer. In this way, the distances from all the coil groups to the first magnetic layer and the second magnetic layer are in phase with each other. Also, by arranging the first auxiliary layer and the second auxiliary layer including the reference ground cable, the different coil groups have similar ground impedance. This further improves the symmetry between the different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0015] According to the fourth possible implementation, in a sixth possible implementation of the common mode filter, the reference ground structure includes a first associated reference ground cable, an intermediate associated reference ground cable, and a second associated reference ground cable. The first associated reference ground cable of one or more first target cables of the first cable, the second cable, and the third cable in the first coil layer is arranged in the first coil layer, and the first associated reference ground cable is located on one side or both sides of the first target cable.

[0016] An intermediate associated reference ground cable of one or more intermediate target cables of the first cable, the second cable, and the third cable in the intermediate coil layer is disposed in the intermediate coil layer, and the intermediate associated reference ground cable is located on one or both sides of the intermediate target cable.

[0017] The second associated reference ground cable of one or more second target cables of the first cable, the second cable, and the third cable in the second coil layer is arranged in the second coil layer, and the second associated reference ground cable is located on one side or both sides of the second target cable. In this way, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase and matched. Also, by arranging the associated reference ground cable, different coil groups have similar ground impedance. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0018] According to the sixth possible implementation, in the seventh possible implementation of the common mode filter, the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable are connected together. Thus, compared with the fourth possible implementation, this possible implementation further ensures that different coil groups have similar ground impedances.

[0019] According to the fourth possible implementation, in an eighth possible implementation of the common mode filter, the reference ground structure is formed by the following metal reference ground layers: a first metal reference ground layer located between the first coil layer and the first magnetic layer; a second metal reference ground layer located between the second coil layer and the second magnetic layer; a third metal reference ground layer located between the first coil layer and the middle coil layer, the third metal reference ground layer being provided with a first receiving hole for receiving a first cable hole, a second cable hole, and a third cable hole passing through the third metal reference ground layer; a fourth metal reference ground layer located between the second coil layer and the middle coil layer, the fourth metal reference ground layer being provided with a first cable hole passing through the third metal reference ground layer, a second cable hole, and a second receiving hole receiving the third cable hole; an intermediate metal reference ground layer, where there are one or more intermediate metal reference ground layers, each intermediate metal reference ground layer being located between two intermediate coil layers and a third receiving hole being provided to receive a first cable hole, a second cable hole, and a third cable hole passing through the third metal reference ground layer; In this way, the distances from all the coil groups to the first magnetic layer and the second magnetic layer are in phase with each other. Also, compared with the common mode filter in another possible implementation, the common mode filter in this possible implementation has a metal reference ground layer, so that the different coil groups have similar ground impedance. This further improves the symmetry between the different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0020] According to the eighth possible implementation, in the ninth possible implementation of the common mode filter, when there are multiple metal reference ground layers, the multiple metal reference ground layers are connected through the reference ground holes, and the reference ground holes are disposed in one or more of the first coil layer, the second coil layer, and the middle coil layer. Also, compared with the sixth possible implementation, this possible implementation can further reduce the difference between the ground impedances of different coil groups.

[0021] According to the first aspect, the second aspect, or any one of the nine possible implementations described above, in a tenth possible implementation of the common mode filter, the common mode filter further includes a third magnetic layer and a fourth magnetic layer parallel to each other. The first coil layer, the intermediate coil layer, and the second coil layer are located between the third magnetic layer and the fourth magnetic layer, the third magnetic layer being perpendicular to the first magnetic layer and the second magnetic layer, and the fourth magnetic layer being perpendicular to the first magnetic layer and the second magnetic layer. In this way, the distances from all the coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer are in phase and matched. Also, compared to a common mode filter arranged in a manner including only the first magnetic layer and the second magnetic layer, this common mode filter allows multiple coil groups to be in the same magnetic environment in two dimensions. This further improves the symmetry between the different coil groups and reduces the longitudinal transmission losses of the common mode filter.

[0022] According to the tenth possible implementation, in an eleventh possible implementation of the common mode filter, the common mode filter further includes a fifth magnetic layer and a sixth magnetic layer parallel to each other.

[0023] The first coil layer, the middle coil layer, and the second coil layer are located between the fifth magnetic layer and the sixth magnetic layer, the fifth magnetic layer being perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer, and the sixth magnetic layer being perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer. In this way, the distances from all the coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer are in phase with each other. In addition, compared with the common mode filter arranged in the manner including only the first magnetic layer and the second magnetic layer, and the manner including only the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer, this common mode filter allows multiple coil groups to exist in the same magnetic environment in three-dimensional space. This further improves the symmetry between the different coil groups and reduces the longitudinal transmission losses of the common mode filter.

[0024] According to the fourth possible implementation, in the twelfth possible implementation of the common mode filter, the reference ground structure includes a metal reference ground coating layer, and the metal reference ground coating layer coats the surface of the common mode filter. In this way, the distances from all coil groups to the magnetic layer are in phase and matched. Also, compared with the common mode filter arranged in the manner in the first aspect, this common mode filter allows multiple coil groups to be in the same reference ground environment and have the same ground impedance in three-dimensional space. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0025] According to the fourth possible implementation, in a thirteenth possible implementation of the common mode filter, the reference ground structure further includes pads and metal reference ground strips connected to the terminals of each coil group. A part of each pad is located on a first side of the common mode filter, and another part of each pad is located on one of a plurality of second sides on the common mode filter and connected to the first side. The metal reference ground strip is located between the pads and surrounds at least a part of the area of ​​the first side of the common mode filter and the second side having the pads. In this way, the distances from all the coil groups to the magnetic layer are in phase and matched. Also, compared to the common mode filter arranged in the manner in the first aspect, this common mode filter allows different coil groups to have similar ground impedances at the pads. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0026] According to a third aspect, an embodiment of the present application provides a terminal device, the terminal device including a common mode filter according to the first aspect, the second aspect, or any one of the aforementioned thirteen possible implementations.

[0027] These and other aspects of the present application may become clearer and more understandable in the description of the following embodiment(s). [Brief description of the drawings]

[0028] The accompanying drawings, which are incorporated in and may constitute a part of this specification, illustrate exemplary embodiments or features and aspects of the present application and, together with the description, serve to explain the principles of the present application.

[0029] [Figure 1a] FIG. 1 is a schematic diagram of a cable structure of a common mode filter in the related art. [Figure 1b] FIG. 1 is a schematic diagram of a cable structure of a common mode filter in the related art. [Figure 1c]FIG. 1 is a schematic diagram of a cable structure of a common mode filter in the related art. [Figure 1d] FIG. 2 is a three-dimensional view of a common mode filter according to an embodiment of the present application; [Figure 1e] FIG. 1 is a main diagram of a common mode filter according to an embodiment of the present application. [Figure 1f] FIG. 2 is a side view of a common mode filter according to an embodiment of the present application. [Figure 1g] FIG. 2 is a top view of a common mode filter according to an embodiment of the present application. [Figure 1h] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 2a] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 2b] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 2c] FIG. 2 is a schematic diagram of a structure of a coil layer of a common mode filter according to an embodiment of the present application. [Figure 3a] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 3b] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 5a] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 5b] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 6a] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 6b] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 6c] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 7a]FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 7b] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 7c] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 8a] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 8b] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 9a] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 9b] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 10a] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 10b] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 11a] FIG. 2 is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. [Figure 11b] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 12a] FIG. 2 is a three-dimensional view of a common mode filter according to an embodiment of the present application; [Figure 12b] FIG. 2 is a diagram of a common mode filter according to an embodiment of the present application. [Figure 12c] FIG. 2 is a diagram of a common mode filter according to an embodiment of the present application. [Figure 12d] FIG. 2 is a diagram of a common mode filter according to an embodiment of the present application. [Figure 13a] FIG. 2 is a three-dimensional view of a common mode filter according to an embodiment of the present application; [Figure 13b] FIG. 2 is a diagram of a common mode filter according to an embodiment of the present application. [Figure 13c] FIG. 2 is a diagram of a common mode filter according to an embodiment of the present application. [Figure 13d] FIG. 2 is a diagram of a common mode filter according to an embodiment of the present application. [Figure 14a] FIG. 2 is a cross-sectional view of a common mode filter according to an embodiment of the present application. [Figure 14b] FIG. 2 is a schematic diagram of multiple coil layers of a common mode filter according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Various exemplary embodiments, features, and aspects of the present application are described in detail below with reference to the accompanying drawings, in which like reference numerals represent elements having the same or similar functions, and in which various aspects of the embodiments are illustrated in the accompanying drawings, which are not necessarily drawn to scale unless specifically indicated.

[0031] The specific word "exemplary" is used herein to mean "serving as an example or embodiment, or illustration." Any embodiment described as "exemplary" is not necessarily described as superior or better than other embodiments.

[0032] Also, in order to better explain the present application, the following specific implementations provide many specific details. Those skilled in the art should understand that the present application may be implemented without some specific details. In some instances, methods, means, components, and circuits well known by those skilled in the art are not described in detail in order to emphasize the main purpose of the present application.

[0033] In the related art, a common mode inductor (a kind of common mode filter) usually includes two coils. The two coils have the same amount of turns and the same phase, and are wound in parallel around the same iron core. Since the common mode coils are wound in the same phase, when equal amplitude phase-inverted differential mode currents flow through the common mode inductor, the differential mode currents can generate magnetic fields opposite to each other in the coils, so that the magnetic fields cancel each other out and reduce the inductance effect. The common mode inductor usually does not attenuate the differential mode current, and the main factor affecting the differential mode current is the resistance of the common mode inductor coil. When equal amplitude in-phase common mode currents flow through the common mode inductor, the common mode currents are in the same direction, so the magnetic fields generated by the common mode currents in the common mode inductor coils are also in the same direction, so that the inductance reactance of the common mode inductor coil is increased and the coils show high impedance. In this way, a strong damping effect is created, so that the common mode current can be attenuated and the filtering effect can be achieved. A common mode filter with more than two cables (i.e., more than two coils) has a wide application prospect in high-speed data transmission. For example, a common mode filter adapted to MIPI (Mobile Industry Processor Interface) in the data transmission mode of C-PHY interface (PHY is an abbreviation of Port Physical Layer in English, and C-PHY is a standard for the port physical layer specified in MIPI) is composed of three coils, which can filter common mode noise through coupling and differentiation between two coils. In the related art, Figure 1a, Figure 1b, and Figure 1c are schematic diagrams of the cable structure of the common mode filter in the related art. The cables labeled "A", "B", and "C" are cables with three different coil groups.As shown in FIG. 1a, the cables of the three coil groups are arranged in an equilateral triangle, the cables of the "A" and "B" coil groups are in the same layer, and the cables of the "C" coil group are in a separate layer. In this way, the distances from the ferrite to the cables of the three coil groups are different, resulting in different phases between different coil groups. When a differential current signal flows through the common mode filter and performs a differential operation between the two coils, it is difficult to completely cancel the common mode current, and as a result, a part of the common mode current is converted into a differential mode current. As a result, a differential mode noise is formed. As shown in FIG. 1b, the cables of the three coil groups are also arranged in an equilateral triangle, and the cables of the "A", "B", and "C" coil groups are all in different layers. In this way, the distances from the ferrite to the cables of the three coil groups are different, resulting in different phases between different coil groups. As a result, there is a problem that the common mode current is converted into a differential mode current. As shown in FIG. 1c. 、「 The cables of coil groups "A", "B" and "C" are in different layers, and the cable of one coil group is wound in two layers. In this way, the distances from the ferrite to the cables of the three coil groups are different, resulting in different phases between different coil groups. As a result, there is a problem that the common mode current is converted into a differential mode current. In summary, the common mode filter components with more than two cables in the related art have a problem of insufficient symmetry, and the common mode noise is easily converted into a differential mode noise, so that the filtering effect of the filter against the common mode interference noise is reduced. In general, the characteristic of the common mode to differential mode conversion of the common mode filter is referred to as the longitudinal transmission loss. How to provide the common mode filter with high symmetry and low longitudinal transmission loss is a technical problem to be solved urgently. In order to solve the aforementioned technical problem, the present application provides a common mode filter.

[0034] The common mode filter provided in the present application includes a plurality of coil groups, a plurality of cable holes, and a first magnetic layer, a second magnetic layer, a first coil layer, a middle coil layer, and a second coil layer parallel to each other. The first coil layer, the middle coil layer, and the second coil layer are successively disposed between the first magnetic layer and the second magnetic layer. The quantity of coil groups can be at least three, and the multiple cables of each coil group are distributed separately in each coil layer. The cable lengths of different coil groups in the same coil layer, the relative positional relationship between the cables, and the cable width ratio are set to obtain a common mode filter with high symmetry and low longitudinal transmission loss. The structural layout settings, such as the quantity of coil groups, the quantity of coil layers, and the quantity and position of cable holes of the common mode filter with different usage requirements can be adjusted correspondingly. Those skilled in the art may make settings based on the requirements, which are not limited in the present application. In order to intuitively and clearly describe the layout of the coil groups in the common mode filter, the following uses the example of "three coil groups are arranged in the common mode filter" for explanation, and "A", "B" and "C" respectively represent three coil groups. If the quantity of the coil groups is more than three, those skilled in the art may refer to the layout setting of "arranging three coil groups in the common mode filter" to make corresponding adjustments, and the details will not be described in this application.

[0035] FIG. 1d is a three-dimensional view of a common mode filter according to an embodiment of the present application. FIG. 1e is a main view of a common mode filter according to an embodiment of the present application. FIG. 1f is a side view of a common mode filter according to an embodiment of the present application. FIG. 1g is a top view of a common mode filter according to an embodiment of the present application. FIG. 1h is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 1h is a cross-sectional view obtained by performing a section along the location of the dotted box area s3 in FIG. 1f. To facilitate understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view FIG. 1h. The dotted box area s2 in FIG. 1e, the dotted box area s3 in FIG. 1f, and the dotted box area s1 in FIG. 1g correspond to the same spatial region of the common mode filter.

[0036] An embodiment of the present application provides a common mode filter. As shown in Fig. 1h, the common mode filter includes a plurality of coil groups (however, the difference between the cables of different coil groups is not shown in Fig. 1h), a plurality of cable holes, and a first magnetic layer 11, a second magnetic layer 12, and a plurality of coil layers parallel to each other, the plurality of coil layers including a first coil layer 21, a second coil layer 22, and one or more intermediate coil layers 23 (however, in Fig. 1h, the plurality of intermediate coil layers are used as an example). At least a first cable, a second cable, and a third cable are disposed on each coil layer. The multiple coil groups include at least a first coil group A, a second coil group B, and a third coil group C (however, since FIG. 1h does not limit the relative positional relationship of cables of different coil groups in the same coil layer, FIG. 1h does not show the first coil group A, the second coil group B, and the third coil group C in a different form, but reference may be made to the illustrations in FIGS. 2a, 3a, 5a, 6a, 6b, 7a, 14a). The multiple cable holes include at least a first cable hole, a second cable hole, and a third cable hole (not shown in FIG. 1h).

[0037] The first coil layer 21 , the middle coil layer 23 and the second coil layer 22 are successively disposed between the first magnetic layer 11 and the second magnetic layer 12 .

[0038] The first coil group A includes a first cable in all coil layers. Specifically, the first coil group A includes a first cable in the first coil layer 21, includes a first cable in the second coil layer 22, and includes a first cable in the intermediate coil layer 23. The second coil group B includes a second cable in all coil layers. Specifically, the second coil group B includes a second cable in the first coil layer 21, includes a second cable in the second coil layer 22, and includes a second cable in the intermediate coil layer 23. The third coil group C includes a third cable in all coil layers. Specifically, the third coil group C includes a third cable in the first coil layer 21, includes a third cable in the second coil layer 22, and includes a third cable in the intermediate coil layer 23.

[0039] The first cable hole is configured to connect a plurality of first cables of a first coil group, the second cable hole is configured to connect a plurality of second cables of a second coil group, and the third cable hole is configured to connect a plurality of third cables of a third coil group. At least two of the first cables, second cables, and third cables in the same coil layer are wound in parallel.

[0040] In this embodiment of the present application, different coil groups are insulated from each other. An insulating layer of insulating material, such as a dielectric, may be added to each cable surface. Alternatively, the insulation between different coil groups is implemented by disposing a gap between different cables of the same coil layer, and an insulating material, such as a dielectric, is disposed between adjacent coil layers. For example, the insulating material may be a resin material, a ceramic material, a polymer material, etc. Those skilled in the art may set up a way to implement the mutual insulation between different coil groups based on the requirements. This is not limited in the present application.

[0041] In this embodiment of the present application, the first cable hole, the second cable hole, and the third cable hole disposed in each intermediate coil layer are not connected to each other or in contact with each other, and are insulated from each other to ensure mutual insulation between different coil groups. The material filled in the first cable hole, the second cable hole, and the third cable hole is a metal, which may be completely the same as the cable material of the corresponding coil group. For example, the material is a metal with good electrical conductivity, such as copper, silver, gold, and tungsten. Alternatively, a different metal may be used for the cable of the corresponding coil group. For example, the cable material of the coil group is copper metal, and the filling material in the cable hole is silver metal. This is not limited in the present application.

[0042] In this embodiment of the present application, the material of the first magnetic layer 11 and the second magnetic layer 12 may be a magnetic material such as ferrite, for example, an alloy, a monomer, an oxide, such as an oxide containing an element such as Fe, Co, Ni, or Mn. This is not limited in the present application. Also, the first magnetic layer 11, the second magnetic layer 12, and adjacent layers in the multiple coil layers (including the first coil layer 21, the second coil layer 22, and one or more intermediate coil layers 23) are insulated from each other. The insulation between adjacent layers may be implemented by adding an insulating layer, etc. The material of the insulating layer may be an insulating material such as a resin material, a ceramic material, or a polymer material. This is not limited in the present application. The first magnetic layer and the second magnetic layer are provided with spatial sizes such as thickness, length, and width, and the thickness, length, and width of the first magnetic layer and the second magnetic layer may be set based on the limitations of processing technology, longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, etc. This is not limited in the present application. However, in order to simplify the structure of the common mode filter, strengthen the cable, and ensure the positional relationship between layers in the common mode filter, the sizes of the first magnetic layer and the second magnetic layer are not described in detail in the accompanying drawings of the present application. However, this cannot be considered as a limitation of the present application.

[0043] In this embodiment of the present application, the parallel winding of at least two of the multiple cables in the same coil layer may include the parallel winding of two or more cables. As shown in each of Figures 2b, 2c, and 3b, the multiple cables in each coil layer are wound in parallel. The parallel winding of at least two of the multiple cables in the same coil layer may include the following: All or a part of each cable in the parallel-wound cables participates in the winding of "all cables wound in parallel", and another part of each cable in the parallel-wound cables participates in parallel with the winding of one or more other cables in "all cables wound in parallel". In this way, the distance from each cable to the first magnetic layer in the same coil layer is consistent, and the distance from each cable to the second magnetic layer is also consistent (however, the distance from the multiple cables to the first magnetic layer in the same coil layer is different from the distance from the multiple cables to the second magnetic layer in the same coil layer). At least two cables in the same coil layer are wound in parallel, meaning that cables that need to be wound in parallel in the same coil layer are wound in parallel. Parallel wound cables have the same phase.

[0044] For example, as shown in Figures 2b and 2c below, the multiple cables in each coil layer are all wound in parallel, and the entire length of each cable joins in parallel to the winding of the multiple cables. As shown in Figure 3b below, the multiple cables in each coil layer are wound in parallel. However, due to different cable lengths, some cables cannot join in parallel winding with all other cables in the same coil layer at their entire length. The remaining length that does not join in "parallel winding with all other cables in the same coil layer" continues to be wound in parallel with one or more of the remaining cables until the entire length is used up. If a cable is the longest cable in a coil layer, the remaining length of the cable cannot be used in any parallel winding. For example, in the "first layer", the first cable a, the second cable b, and the third cable c are wound in parallel, but , No.Only the entire length of cable b in 2 is involved in the parallel winding of the three cables. No. A part of the third cable c joins the parallel winding of the three cables, another part of the third cable c joins the parallel winding with the second cable b, and the last part of the third cable c does not join the parallel winding. As shown in FIG. 4, all the cables in each coil layer are wound in parallel, but due to the different cable length restrictions, in the "sixth layer", only a small part of the second cable b joins the parallel winding of the three cables, and the remaining part is wound in parallel with the third cable c. R .

[0045] It should be noted that in the actual manufacturing process of the common mode filter, the multiple coil layers, the first magnetic layer, and the second magnetic layer are directly contacted and attached closely to each other. In the examples provided in the accompanying drawings of this application, the distances between different layers are only used to more clearly illustrate the structure of the common mode filter, and are not limited in this application.

[0046] By arranging the common mode filter in the manner shown in FIG. 1h, the distances from all coil groups, including at least the first coil group, the second coil group, and the third coil group, to the first magnetic layer and the second magnetic layer are in phase and matched, thereby improving the symmetry between the different coil groups and reducing the longitudinal transmission loss of the common mode filter.

[0047] FIG. 2a is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 2b is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. FIG. 2a is a cross-sectional view obtained by performing a section along the location of the dotted box region s3 in FIG. 1h. To facilitate the understanding of the cable layout of the coil groups in the present application, only the parts associated with the coil groups are shown in the cross-sectional view FIG. 2a. In a possible implementation, in each coil layer, the relative positional relationship between the cables of different coil groups is the same. In the same coil layer, the center lines of the cable holes of all coil groups are located in the same cross section perpendicular to the coil layer. Different segments of each cable in the same coil layer may be perpendicular to the cross section, parallel to the cross section, or located in the cross section. In the first coil layer 21, there is a first relative positional relationship between the first cable belonging to the first coil group A, the second cable belonging to the second coil group B, and the third cable belonging to the third coil group C. In the second coil layer, there is a second relative positional relationship between the first cable belonging to the first coil group A, the second cable belonging to the second coil group B, and the third cable belonging to the third coil group C. In the middle coil layer, there is an intermediate relative positional relationship between the first cable belonging to the first coil group A, the second cable belonging to the second coil group B, and the third cable belonging to the third coil group C. As shown in Fig. 2a and Fig. 2b, the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same, and the centerlines of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc, which are for connecting cables in adjacent coil layers, are all located in the same cross section perpendicular to all coil layers. The "circular dotted box" disposed on the cable in Fig. 2b is the location of the cable hole connected to the cable.

[0048] As shown in FIG. 2b, in each coil layer, the cables labeled "a", "b", and "c" are the first, second, and third cables of the coil layer in which the cables are located. Specifically, the first cable is labeled "a", the second cable is labeled "b", and the third cable is labeled "c". In this case, the cables of the first coil group A are the cables labeled "a" in the first coil layer, i.e., "first layer", the middle coil layer, i.e., the second layer to the fifth layer, and the second coil layer, i.e., the sixth layer. The cables of the second coil group B are the cables labeled "b" in the first coil layer, i.e., "first layer", the middle coil layer, i.e., the second layer to the fifth layer, and the second coil layer, i.e., the sixth layer. The cables of the third coil group C are the cables designated "c" in the first coil layer, i.e., "first layer", the intermediate coil layers, i.e., layers 2 through 5, and the second coil layer, i.e., "sixth layer".

[0049] In this implementation, the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship may refer to adjacent or neighboring relationships between the cables. As shown in FIG. 2b, "the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same" means that in each of the first coil layer, i.e., "first layer", the intermediate coil layer, i.e., "second layer to fifth layer", and the second coil layer, i.e., "sixth layer", the relative positional relationships are that the first cable a is the outermost, the third cable c is the innermost, and the second cable b is between the first cable a and the third cable c, i.e., the three cables are in an "abc" positional relationship.

[0050] In this implementation, as shown in FIG. 2b, the "third layer" in the middle coil layer 23 and the "first cable hole Aa, the second cable hole Bb, and the third cable hole Cc for implementing cable connection in each coil group in the second layer and the third layer" are used as an example. The first cable hole Aa corresponding to the first coil group A, the first cable hole Bb corresponding to the second coil group B, and the first cable hole Cc corresponding to the third coil group C are disposed in the "third layer" and between the "third layer" and the "second layer". The centerlines (i.e., the dashed lines shown in FIG. 2b) of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc are located on the same cross section M, and the cross section M is perpendicular to all coil layers. However, the first cable a, the second cable b, and the third cable c in the "third layer" each have multiple different segments. Using the first cable a in the “third layer” as an example, the first cable a includes segments a1, a2, a3, a4, and a5, where segment a1 is perpendicular to cross section M, segment a2 is parallel to cross section M, segment a3 is perpendicular to cross section M, segment a4 is parallel to cross section M, and segment a5 is perpendicular to cross section M. Similarly, the center lines of "the first cable hole Aa, the second cable hole Bb and the third cable hole Cc for cable connection of each coil group in the first and second layers," "the first cable hole Aa, the second cable hole Bb and the third cable hole Cc for cable connection of each coil group in the third and fourth layers," "the first cable hole Aa, the second cable hole Bb and the third cable hole Cc for cable connection of each coil group in the fourth and fifth layers," and "the first cable hole Aa, the second cable hole Bb and the third cable hole Cc for cable connection of each coil group in the fifth and sixth layers" are also located on the corresponding cross sections.

[0051] In Fig. 2b, Fig. 3b, Fig. 4, Fig. 5b, Fig. 6c, Fig. 7b, Fig. 7c and Fig. 14b in this application, in order to simplify the winding method of the cable in multiple coil groups and to clearly describe the winding structure, it should be noted that the number of turns of the first cable, the second cable and the third cable in each coil layer is less than two. In actual production and manufacturing, the number of turns of the first cable, the second cable and the third cable in each coil layer can be any number, such as one or more turns. Also, in order to avoid the stress problems caused by tip discharge and right angle bending, and to make the differential mode loss and the return loss of the common mode filter smaller, the corner position of the cable during the winding period can be made into a circular arc shape (as shown in Fig. 2c below).

[0052] In this implementation, the quantity of multiple coil layers may be set based on limitations of the longitudinal transmission loss, differential mode loss, return loss, and impedance indicator parameters of the common mode filter.

[0053] In this implementation, the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc required for cable connection of the coil groups between two adjacent coil layers (the first coil layer and the adjacent intermediate coil layer, the second coil layer and the adjacent intermediate coil layer, or the two adjacent intermediate coil layers) may be disposed in any one of the two coil layers or may be disposed between the two coil layers. Alternatively, the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc may extend through each coil layer. The connection positions (positions where the cable holes contact the coil layers) corresponding to the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc in different coil layers may be the same or different. Provided that it is ensured that the electrical connection of the cables in the first coil group, the second coil group, and the third coil group can be implemented by using the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc, the positions of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc may be set based on the actual requirements. This is not limited in the present application. For example, the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc required for the electrical connection between the cables in the coil group between the first coil layer and the adjacent intermediate coil layer may be disposed in the intermediate coil layer, may be disposed in the first coil layer, or may be disposed between the first coil layer and the intermediate coil layer. The first cable hole Aa, the second cable hole Bb, and the third cable hole Cc required for electrical connection between the cables in the coil group between the second coil layer and the adjacent intermediate coil layer may be disposed in the intermediate coil layer, may be disposed in the second coil layer, or may be disposed between the intermediate coil layer and the second coil layer. The first cable hole Aa, the second cable hole Bb, and the third cable hole Cc required for connection between the cables in the coil group between two adjacent intermediate coil layers may be disposed in any one of the two intermediate coil layers, or may be disposed between the two intermediate coil layers.It should be noted that in practice, different coil layers are in direct contact and attached closely to each other. In the example provided in FIG. 2b of the present application, the length of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc is much longer than the thickness of the coil layers, so that the structure of the common mode filter is more clearly shown. The actual length of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc in the common mode filter is not limited.

[0054] By arranging the common mode filter in the manner shown in Figures 2a and 2b, the distances from all coil groups to the first and second magnetic layers are in phase with each other. Also, compared to the common mode filter arranged in the manner shown in Figure 1h, the distances from all coil groups to the first and second magnetic layers are in phase with each other. I , the relative positional relationship between the cables of different coil groups is the same, so that the symmetry between different coil groups is further improved and the longitudinal transmission loss of the common mode filter is further reduced.

[0055] In this embodiment of the present application, each cable of different coil groups has a thickness and width, and there may also be cable spacing between adjacent cables in the same coil layer. Also, the cable thickness and width, as well as the cable spacing, may be set based on the limitations of the longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, processing technology, etc. of the common mode filter. The appearance length, width, and thickness of the common mode filter used for the terminal device are 0.1 mm to 1 mm, that is, the length, width, and height of the three-dimensional space occupied by the common mode filter are 0.1 mm to 1 mm. An example is used in which the length, width, and thickness of the common mode filter are 1 mm. When the common mode filter uses technologies such as Low Temperature Co-fired Ceramic (LTCC), thin film lamination technology, and Integrated Passive Device (IPD) technology, the cable width is 5 μm to 30 μm, and the cable spacing is 5 μm to 30 μm, due to the limitations of the technology, the size of the common mode filter, the longitudinal transmission loss, the differential mode loss, the return loss, and the impedance. When the common mode filter is processed and manufactured by using printing technology or electroplating technology, the cable thickness can be 0.1 μm to 10 μm. Those skilled in the art can set the cable thickness, cable width, and cable spacing based on the actual design requirements of the common mode filter. This is not limited in the present application. When the common mode filter is used, it is considered that it is necessary to ensure that the impedance of the common mode filter is small, that is, the differential mode loss is small, in other words, the differential mode current is not lost. Therefore, when a common mode filter is manufactured, the distance between the cable layers should be large enough to avoid the existence of stray capacitance, and the cable should be thick enough to avoid excessive DC resistance. The common mode filter should also have a specific filtering frequency band, and the filtering frequency band control is generally implemented by adding ferromagnetic materials.Specifically, the ferromagnetic material is added to the upper and lower surfaces of the common mode filter. The ferromagnetic material has a tangent of the loss angle, which is a function of frequency. At some frequencies, the tangent of the loss angle is large. When a common mode noise current flows through the common mode filter, the magnetic field generated by the common mode current is dissipated in the ferromagnetic material in the form of thermal energy. Also, the common mode filter provided in this application can be manufactured independently. The size of the manufactured common mode filter is large and can meet the design requirements of the common mode filter regarding the cable thickness and cable width as much as possible. The common mode filter can be manufactured by using various manufacturing techniques, and the manufacturing of the common mode filter has low resource cost, low time cost, and high reliability.

[0056] In a possible implementation, the cable widths of the different cables in each coil layer of the common mode filter are set based on a preset width ratio relationship.

[0057] The width ratio relationship may include any one of the following relationships: the multiple coil groups include one or more target coil groups and at least two same-width coil groups, where the cables of the different same-width coil groups have the same first cable width and a different first width ratio relationship exists between the second cable width and the first cable width of the cables of each target coil group, the multiple coil groups include one or more target coil groups and at least two same-width coil groups, where the cables of the different same-width coil groups have the same first cable width and the cables of the different target coil groups have the same second cable width and a second width ratio relationship exists between the second cable width and the first cable width, the cable widths of the cables of all coil groups are different from one another and a third width ratio relationship exists between the cable widths of the cables of the different coil groups, or a corresponding fourth width ratio relationship exists between the cable widths of the different cables in each coil layer.

[0058] The cable width of the cable of each coil group can be the width of all the cables of the coil group in different coil layers. Different cables of the same coil group may be set to have the same cable width, or different cables of the same coil group may be set to have cable widths that are not completely the same or different from each other. In the case where different cables of the same coil group have the same cable width, when the width ratio relationship is set, a first cable width of the coil group with the same width may be determined first, and then the cable width of the target coil group is adjusted based on the width ratio relationship. The width ratio relationship between the first cable width W1 and the second cable width W2 is W1=p1×W2, where p1 is a ratio coefficient, and p1∈[0.5, 0.8] or p1∈[2, 3]. The multiple cables in the same coil layer may further be set to have cable widths that are not completely the same. A reference cable may be determined from the multiple cables first. A fourth ratio relationship between the cable width w1 of the reference cable and the cable width w2 of the other cable is w1=p1×w2, where p1 is a ratio coefficient; p 1 ∈ [0.5, 0.8] or p 1∈[2, 3].

[0059] In this way, the cable width of each coil group is set based on the preset width ratio relationship, so that the impedance difference caused by the different total length of the multiple cables in different coil groups, the different cable thickness of different coil groups caused by the processing technology, and the mismatched phase of the cables in different coil groups caused by the position setting of the cable hole can be further improved. The cable width of different coil groups can be adjusted by adjusting the width ratio relationship, so that the different coil groups have similar or the same characteristic impedance, the symmetry between the different coil groups is improved, and the longitudinal transmission loss of the common mode filter is reduced. When the cable thickness is the same, a smaller cable width corresponds to a larger impedance. Since the impedance value is inversely proportional to the cross-sectional area of ​​the cable, the smaller the cable width, the smaller the cross-sectional area of ​​the cable.

[0060] To briefly explain different methods of setting the width ratio relationship, the following uses an example in which the multiple coil groups include a first coil group A, a second coil group B, and a third coil group C for illustration. FIG. 2c is a schematic diagram of the structure of a coil layer of a common mode filter according to an embodiment of the present application. The difference between FIG. 2c and FIG. 2b is that in FIG. 2c, the cable width is set, and the cable wiring corner is set to a circular arc shape. Therefore, FIG. 2c only shows the cable of the first coil layer "first layer". There is only one target coil group, and in the multiple coil groups, all coil groups except "one target coil group" are coil groups of the same width. As shown in FIG. 2c, when the multiple coil groups include a first coil group A, a second coil group B, and a third coil group C, any one of the first coil group A, the second coil group B, and the third coil group C may be selected as the target coil group, and the other coil groups are coil groups of the same width. For example, the third coil group C is the target coil group, and the first coil group A and the second coil group B are coil groups of the same width. In this case, W1a=W1b=p1*W2c, and p1∈[0.5, 0.8]. The first cable a of the first coil group A, the second cable b of the second coil group B, and the third cable c of the third coil group C are arranged continuously from the outside to the inside, and the number of turns is greater than 1, so the cable width of the first cable a and the cable width of the second cable b can be reduced. However, the impedance cannot be adjusted by increasing the cable width of the third cable c. This is because, if it is ensured that the first cable a, the second cable b, and the third cable c have the same cable spacing and the same coupling condition, increasing the width of the third cable c will bring the third cable c and the first cable a closer to each other, even causing a short circuit caused by the connection between the third cable c and the first cable a.

[0061] In the following description of the embodiments of the present application, in fact, all the cables shown in Figures 3b, 4, 5b, 6c, 7b, 7c, 8a, 9a, 10a, 11a, and 14b are cables having the thickness and width shown in Figure 2b. However, in order to simplify the structure of the common mode filter, strengthen the cable, and ensure the positional relationship between the layers of the common mode filter, only "lines" having widths are used to illustrate the cables in Figures 3b, 4, 5b, 6c, 7b, 7c, 8a, 9a, 10a, 11a, and 14b.

[0062] In the example shown in FIG. 2b in this embodiment of the present application, the diameters of the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc are the same as the width of the cable connected to the first cable hole Aa, the second cable hole Bb, and the third cable hole Cc. In practice, the diameters of the cable holes can be set based on the processing technology (such as laser drilling or photolithography technology), the electrical connection requirements between the cables, and the width of the cables. The diameters of the cable holes can be larger, smaller, or equal to the width of the cable connected to the cable hole. This is not limited in the present application. Similarly, in Figures 3b, 4, 5b, 6c, 7b, 7c, 8a, 9a, 10a, 11a, and 14b, two ends of each cable in the middle coil layer, one end of each cable in the first coil layer, and one end of each cable in the second coil layer are each depicted with a cable hole (i.e., a circle with a different gray scale shown in the figures). To simply indicate the location of the cable hole, the diameter of the cable hole is larger than the width of the cable connected to the cable hole. However, in practice, the diameter of the cable hole may be larger, smaller, or equal to the width of the cable connected to the cable hole. In other words, the size relationship between the diameter of the cable hole and the width of the cable connected to the cable hole shown in Figures 2b, 3b, 4, 5b, 6c, 7b, 7c, 8a, 9a, 10a, 11a, and 14b is not limited in the present application.

[0063] FIG. 3a is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 3b is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. FIG. 3a is a cross-sectional view obtained by performing a section along the location of the dotted box region s3 in FIG. 1f. To facilitate the understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view FIG. 3a. In a possible implementation, the total winding length of different coil groups is similar, the total length is the sum of the lengths of multiple cables in the same coil group, and the relative positional relationship between the cables of different coil groups in each coil layer is different. As shown in FIG. 3a and FIG. 3b, in the first coil layer 21, there is a first relative positional relationship between the first cable belonging to the first coil group A, the second cable belonging to the second coil group B, and the third cable belonging to the third coil group C. In the second coil layer, a second relative positional relationship exists between the first cable belonging to the first coil group A, the second cable belonging to the second coil group B, and the third cable belonging to the third coil group C. In the intermediate coil layer, an intermediate relative positional relationship exists between the first cable belonging to the first coil group A, the second cable belonging to the second coil group B, and the third cable belonging to the third coil group C. The first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are different, and a first total length of the multiple cables of the first coil group A, a second total length of the multiple cables of the second coil group B, and a third total length of the multiple cables of the third coil group C are the same.

[0064] In this implementation, in the actual processing of the common mode filter, the first total length, the second total length, and the third total length are affected by the processing technology, and the three cannot be completely the same in practice. Therefore, in this application, "the first total length, the second total length, and the third total length are the same" is a theoretical state, and "the first total length, the second total length, and the third total length" in the actually manufactured common mode filter are basically the same and approximately equal. Alternatively, the length difference may be set based on indicator requirements related to the common mode filter, such as differential mode loss, longitudinal transmission loss, and the required total winding length of the multiple cables in each coil group, so that the actual length difference between the first total length, the second total length, and the third total length is less than the above length difference, ensuring that the total winding length of the cables in different coil groups is as similar as possible, and further improving the symmetry between different coil groups. A smaller length difference indicates that the total winding lengths of the different coil groups are closer (specifically, the first total length, the second total length, and the third total length are closer) and that there is better symmetry between the different coil groups.

[0065] In this implementation, as shown in Figures 3a and 3b, the relative positional relationship between the cables of different coil groups in each coil layer is different. The relative positional relationship between the first cable a, the second cable b, and the third cable c in the "first layer" (first coil layer 21) may be "abc", the relative positional relationship between the first cable a, the second cable b, and the third cable c in the "second layer" (intermediate coil layer 23) is "cab", and the relative positional relationship between the first cable a, the second cable b, and the third cable c in the "third layer" (intermediate coil layer 23) is "bca". In the "fourth layer" (intermediate coil layer 23), the relative positional relationship between the first cable a, the second cable b, and the third cable c is "cab", in the "fifth layer" (intermediate coil layer 23), the relative positional relationship between the first cable a, the second cable b, and the third cable c is "bca", and in the "sixth layer" (second coil layer 22), the relative positional relationship between the first cable a, the second cable b, and the third cable c is "abc". That is, in the multiple coil layers, multiple layers having the same relative positional relationship between the first cable a, the second cable b, and the third cable c are the "first layer and the sixth layer". However, the relative positional relationship between the first cable a, the second cable b, and the third cable c in all coil layers is not completely the same. For example, the relative positional relationships between the first cable a, the second cable b, and the third cable c in the first and sixth layers, the third and fifth layers, and the second and fourth layers are the same individually, while the relative positional relationships in other different layers are different.

[0066] In this implementation, the quantity of the multiple coil layers and the sum of the winding lengths of each coil group can be set based on the limitations of the longitudinal transmission loss, return loss, and impedance indicator parameters of the common mode filter, which are not limited in this application.

[0067] By arranging the common mode filter in the manner shown in Figures 3a and 3b, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase with each other. Also, compared with the common mode filter arranged in the manner shown in Figures 2a and 2b, in this common mode filter, the relative positional relationship between the cables of different coil groups in each coil layer is changed (specifically, the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are changed), so that the total length of the cables of different coil groups is similar. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0068] In a possible implementation, Fig. 4 is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. The difference between the manners of arranging different coil groups in multiple coil layers shown in Fig. 4 and Fig. 3a and Fig. 3b is that the relative positional relationship between the cables is arranged in a different manner. As shown in Fig. 4, the first relative positional relationship, the second relative positional relationship and the intermediate relative positional relationship are the same, and the first total length of the multiple cables of the first coil group, the second total length of the multiple cables of the second coil group, and the third total length of the multiple cables of the third coil group are the same.

[0069] In this implementation, as shown in Fig. 4, the relative positional relationship between the first cable a, the second cable b, and the third cable c in each coil layer is the same (i.e., the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same). However, in order to satisfy the requirement that the total winding length between different coil groups is the same, the winding length of the first cable, the second cable, and / or the third cable in the same coil group may be more than one turn, or may be less than one turn. In other words, the length of the first cable, the second cable, and the third cable in the same coil layer is not limited.

[0070] By arranging the common mode filter in the manner shown in Figure 4, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase with each other. Also, compared with the common mode filter arranged in the manner shown in Figures 2a and 2b, in this common mode filter, the lengths of the cables in different coil layers are changed based on the fact that the relative positional relationship between the cables of different coil groups in each coil layer is the same, so that the total lengths of the cables of different coil groups are the same. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0071] Based on some common mode filters provided in Figures 2a, 2b, 3a, 3b and 4, in this application, the common mode filter may further include a reference ground structure. The reference ground structure is insulated from each of the first cables, each of the second cables and each of the third cables, and the reference ground structure is insulated from both the first magnetic layer and the second magnetic layer. The reference ground structure may be the "reference ground" of the cables in each coil group through connection to a ground pin, air connection, floating connection, etc. This is not limited in this application. By disposing the reference ground structure, different coil groups may have similar ground matching impedance or even the same matching impedance, so that the symmetry between different coil groups is further improved and the longitudinal transmission loss of the common mode filter is reduced.

[0072] The implementation of the ground reference structure may include the following implementations of Method 1 to Method 4. In the common mode filter, one or more methods of Method 1 to Method 4 may be selected to arrange the ground reference structure.

[0073] Approach 1: The ground reference structure may be one or more internal ground reference layers located within the common mode filter, such as the "metal ground reference layers" described below.

[0074] Method 2: The reference ground structure may be one or more internal reference ground conductive cable layers located inside the common mode filter, and at least one reference ground cable providing a "reference ground" for the cable in the adjacent coil layer is disposed in the reference ground conductive cable layer. A corresponding reference ground conductive cable layer may be set for each coil layer, a corresponding reference ground conductive cable layer may be set for some coil layers, or a corresponding reference ground conductive cable layer may be set for each coil layer. Electric Cable A layer may be set for some coil layers and used as a "reference ground" for all coil layers. For example, the "first auxiliary layer and second auxiliary layer" described below are the "reference ground" for all coil layers.

[0075] Approach 3: The reference ground structure may be one or more associated reference ground cables located in the coil layer of the common mode filter, such as the “first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable” described below.

[0076] Approach 4: The ground reference structure may be a surface ground reference structure located on the surface of the common mode filter, such as a "metal ground reference coating layer" or a "metal ground reference strip" described below.

[0077] It can be understood that those skilled in the art can set the position, structure, size, etc. of the reference ground structure in the common mode filter based on requirements, provided that it is ensured that the reference ground structure can provide a reference ground for the cable of the coil group. Different coil groups can even have similar or the same ground matching impedance. This is not limited in the present application.

[0078] FIG. 5a is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 5b is a schematic diagram of a structure of a common mode filter according to an embodiment of the present application. FIG. 5a is a cross-sectional view obtained by performing a section along the location of the dotted box region s3 in FIG. 1c. To facilitate the understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view FIG. 5a. In a possible implementation, as shown in FIG. 5a and FIG. 5b, the reference ground structure may include a first auxiliary layer 31 and a second auxiliary layer 32. The first auxiliary layer 31 is located between the first coil layer 21 and the first magnetic layer 11, and the first auxiliary layer 31 is separated from the first coil layer 21 by using an insulating medium to prevent the first auxiliary layer 31 from being electrically connected to the first coil layer 21. The first auxiliary layer 31 is provided with a first reference ground cable 41 that corresponds separately to the first cable a, the second cable b, and the third cable c in the first coil layer 21. Specifically, the first reference ground cable 41 includes a reference ground cable segment Da of the first cable a in the first coil layer 21, a reference ground cable segment Db of the second cable b in the first coil layer 21, and a reference ground cable segment Dc of the third cable c in the first coil layer 21. The second auxiliary layer 32 is located between the second coil layer 22 and the second magnetic layer 12. Similarly, the second auxiliary layer 32 is separated from the second coil layer 22 by using an insulating medium to prevent the second auxiliary layer 32 from being electrically connected to the second coil layer 22. The second auxiliary layer 32 is provided with a second reference ground cable 42 that separately corresponds to the first cable a, the second cable b, and the third cable c in the second coil layer 22. Specifically, the second reference ground cable 42 includes a reference ground cable segment Fa of the first cable a in the second coil layer 22, a reference ground cable segment Fb of the second cable b in the second coil layer 22, and a reference ground cable segment Fc of the third cable c in the second coil layer 22.

[0079] In this implementation, the first auxiliary layer 31 and the second auxiliary layer 32 can be electrically connected through the auxiliary layer holes. The first auxiliary layer 31 and the second auxiliary layer 32 can be "floating" between the magnetic layer and the coil layer, i.e., the auxiliary layers do not need to be electrically connected. If the auxiliary layers are electrically connected through the auxiliary layer holes, the auxiliary layer holes cannot be electrically connected to any cables or cable holes in the coil layer.

[0080] In order to facilitate the description of the setting of the first auxiliary layer 31 and the second auxiliary layer 32 in the common mode filter, only "FIGS. 3a and 3b" are used as an example to describe the setting of adding the first auxiliary layer 31 and the second auxiliary layer 32 in FIG. 5a and 5b. Those skilled in the art can add the first auxiliary layer 31 and the second auxiliary layer 32 to the common mode filter in "FIGS. 2a and 2b" and "FIG. 4" according to the setting of the first auxiliary layer 31 and the second auxiliary layer 32 in FIG. 5a and 5b. The details will not be described again in this specification.

[0081] In this implementation, as shown in Figures 5a and 5b, the positions and layout of the reference ground cable segments in the first reference ground cable 41 and the second reference ground cable 42 are the same as the positions and layout of the corresponding cables, ensuring that different coil groups have similar ground impedances.

[0082] By arranging the common mode filter in the manner shown in Figures 5a and 5b, the distances from all coil groups to the first and second magnetic layers are in phase with each other. Also, by arranging the first and second auxiliary layers including the reference ground cable, different coil groups have similar ground impedances compared to the common mode filter arranged in the manner without adding the first and second auxiliary layers in Figures 3a, 3b, etc. (i.e., the manner corresponding to Figures 2a, 2b, 4, etc.). This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0083] Based on some common mode filters provided in Figures 2a, 2b, 3a, 3b, and 4, Figures 6a and 6b are cross-sectional views of a common mode filter according to an embodiment of the present application, and Figure 6c is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. Figures 6a and 6b are cross-sectional views obtained by performing a section along the location of the dotted box region s3 in Figure 1f. To facilitate understanding of the cable layout of the coil group in the present application, only the parts associated with the coil group are shown in the cross-sectional views 6a and 6b. In a possible implementation, as shown in Figures 6a, 6b, and 6c, the reference ground structure may include a first associated reference ground cable, an intermediate associated reference ground cable, and a second associated reference ground cable. A first associated reference ground cable 51 of one or more cables among the first cable a, the second cable b, and the third cable c in the first coil layer 21 is disposed in the first coil layer 21, and the first associated reference ground cable 51 is located on one side or both sides of the first target cable. An intermediate associated reference ground cable 53 of one or more intermediate target cables among the first cable a, the second cable b, and the third cable c in the intermediate coil layer 23 is disposed in the intermediate coil layer 23, and the intermediate associated reference ground cable 53 is located on one side or both sides of the intermediate target cable. A second associated reference ground cable 52 of one or more second target cables among the first cable a, the second cable b, and the third cable c in the second coil layer 22 is disposed in the second coil layer 22, and the second associated reference ground cable 52 is located on one side or both sides of the second target cable. The materials of the first, intermediate and second associated reference ground cables and the materials of the cables may be the same type of metal or may be different types of metal.

[0084] 6a and 6c show that the first associated reference ground cable 51 is disposed on one side (outside) of the first cable a, the second cable b, and the third cable c in the first coil layer 21, i.e., the first cable a, the second cable b, and the third cable c in the first coil layer 21 are first target cables, and the second associated reference ground cable 52 is disposed on one side (outside) of the first cable a, the second cable b, and the third cable c in the second coil layer 22. This figure only shows that the intermediate coil layer 23 is disposed on one side (outside) of the first cable a, the second cable b, and the third cable c in the second coil layer 22, i.e., the first cable a, the second cable b, and the third cable c in the second coil layer 22 are second target cables, and that the intermediate associated reference ground cable 53 is disposed on one side (outside) of the first cable a, the second cable b, and the third cable c in the intermediate coil layer 23, i.e., the first cable a, the second cable b, and the third cable c in the intermediate coil layer 23 are intermediate target cables. FIG. 6b only shows that the first associated reference ground cable 51 is disposed on both sides of the first cable a, the second cable b, and the third cable c in the first coil layer 21, i.e., the first cable a, the second cable b, and the third cable c in the first coil layer 21 are first target cables, and that the second associated reference ground cable 52 is disposed on both sides of the first cable a, the second cable b, and the third cable c in the second coil layer 22, i.e., the first cable a, the second cable b, and the third cable c in the second coil layer 22 are second target cables, and that the intermediate associated reference ground cable 53 is disposed on both sides of the first cable a, the second cable b, and the third cable c in the intermediate coil layer 23, i.e., the first cable a, the second cable b, and the third cable c in the intermediate coil layer 23 are intermediate target cables. For configuration of the first associated reference ground cable 51, the second associated reference ground cable 52, and the intermediate associated reference ground cable 53 in another manner, please refer to the example layout provided in Figures 6a, 6b, and 6c.The details will not be described again in this application.

[0085] In this implementation, in the actual cable wiring process, the position of the accompanying reference ground cable in each coil layer, the quantity of the accompanying cable, and the specific cable in the first cable, the second cable, and the third cable to be accompanied can be set based on the use requirements of the common mode filter that need to be met by the layout settings of the first cable, the second cable, and the third cable in different coil layers. That is, the settings of the accompanying reference ground cable in different coil layers can be the same or different. In this way, the symmetry of different coil groups can be improved, and different coil groups have similar ground impedance. Those skilled in the art can adjust whether the reference ground cable is arranged for the first cable, the second cable, and the third cable in each coil layer, whether the reference ground cable is arranged on one side or on both sides, and whether the reference ground cable is arranged inside or outside based on the actual requirements. This is not limited in the present application.

[0086] For example, the multiple coil layers are assumed to be a first layer, a second layer, ..., and a sixth layer, where the "first layer" is the first coil layer, the "second layer through fifth layers" are the middle coil layers, and the "sixth layer" is the second coil layer. In this case, in the "first layer", the first associated reference ground cable 51 may be arranged only on one side of the first cable a; in the "second layer", the intermediate associated reference ground cable 53 may be arranged only on both sides of the first cable a; in the "third layer", the intermediate associated reference ground cable 53 may be arranged only on both sides of the first cable a and the second cable b; in the "fourth layer", the intermediate associated reference ground cable 53 may be arranged only on both sides of the first cable a, the second cable b, and the third cable c; in the "fifth layer", the intermediate associated reference ground cable 53 may be arranged only on the outside of the first cable a, the second cable b, and the third cable c; and in the "sixth layer", the second associated reference ground cable 52 may be arranged only on the inside of the first cable a, the second cable b, and the third cable c.

[0087] By arranging the common mode filter in the manner shown in Figures 6a, 6b, and 6c, the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase with each other. Also, compared with a common mode filter arranged in the manner without the accompanying reference ground cable in Figure 4, etc. (i.e., the manner corresponding to Figures 2a, 2b, 3a, 3b, etc.), by arranging the first accompanying reference ground cable, the second accompanying reference ground cable, and the intermediate accompanying reference ground cable, different coil groups have similar ground impedances. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0088] In a possible implementation, the associated reference ground cables in different coil layers may be connected to each other, specifically, the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable may be connected to each other or not connected to each other. Some or all of the associated reference ground cables in the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable may be connected to each other or not connected to each other based on the ground impedance of the different coil groups. If the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable need to be connected, the connection between the associated reference ground cables may be implemented by disposing holes in the corresponding coil layers, or the connection between the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable may be implemented through an external conductive cable. The material of the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable may be metal. In this manner, compared to a technique in which the first, intermediate, and second auxiliary reference ground cables are not connected, this technique can further ensure similar ground impedances of different coil groups.

[0089] In a possible implementation, the ground reference structure may include the following metal ground reference layers: a first metal reference ground layer located between the first coil layer and the first magnetic layer; a second metal reference ground layer located between the second coil layer and the second magnetic layer; a third metal reference ground layer located between the first coil layer and the middle coil layer, the third metal reference ground layer being provided with a first receiving hole for receiving a first cable hole, a second cable hole, and a third cable hole passing through the third metal reference ground layer; a fourth metal reference ground layer located between the second coil layer and the middle coil layer, the fourth metal reference ground layer being provided with a first cable hole passing through the third metal reference ground layer, a second cable hole, and a second receiving hole receiving the third cable hole; an intermediate metal reference ground layer, where there are one or more intermediate metal reference ground layers, each intermediate metal reference ground layer being located between two intermediate coil layers and a third receiving hole being provided to receive a first cable hole, a second cable hole, and a third cable hole passing through the third metal reference ground layer; may include at least one of:

[0090] In this implementation, the quantity and type of metal reference ground layers can be determined based on the magnitude of difference between the ground impedances of different coil groups after different types of metal reference ground layers are set. For example, based on some common mode filters provided in Fig. 2a, Fig. 2b, Fig. 3a, Fig. 3b, and Fig. 4, Fig. 7a is a cross-sectional view of a common mode filter according to an embodiment of the present application, and Fig. 7b is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. Fig. 7a is a cross-sectional view obtained by performing a section along the location of the dotted box region s3 in Fig. 1f. To facilitate understanding of the cable layout of the coil groups in the present application, only the parts associated with the coil groups are shown in the cross-sectional view Fig. 7a. As shown in Fig. 7a and Fig. 7b, the common mode filter includes six coil layers, namely, "first layer, second layer, ..., and sixth layer". The "first layer" is the first coil layer, the "second layer to fifth layer" are the middle coil layers, and the "sixth layer" is the second coil layer. The reference ground structure includes a first metal reference ground layer 61, a second metal reference ground layer 62, a third metal reference ground layer 63, a fourth metal reference ground layer 64, and three intermediate metal reference ground layers 65. The third metal reference ground layer 63 is further provided with a first receiving hole 630 corresponding to the first cable hole, the second cable hole, and the third cable hole for implementing "cable connection between the coil groups in the first layer and the second layer". The fourth metal reference ground layer 64 is further provided with a second receiving hole 640 corresponding to the first cable hole, the second cable hole, and the third cable hole for implementing "cable connection between the coil groups in the fifth layer and the sixth layer". The three intermediate metal reference ground layers 65 are further provided with third receiving holes 650 corresponding to the first cable hole, the second cable hole and the third cable hole for implementing the "cable connection between the coil groups in the second layer and the third layer", the "cable connection between the coil groups in the third layer and the fourth layer" and the "cable connection between the coil groups in the fourth layer and the fifth layer".

[0091] As shown in FIG. 7b, the same receiving hole may be arranged for the first cable hole, the second cable hole, and the third cable hole passing through the metal reference ground layer (although, for example, the receiving hole is the first receiving hole, the second receiving hole, or the third receiving hole). The receiving hole may simultaneously receive the first cable hole, the second cable hole, and the third cable hole. Alternatively, a corresponding receiving hole may be arranged for each cable hole. The receiving hole and the received cable hole are insulated from each other, and the insulation may be implemented by using dielectric insulation, setting physical spacing, etc. In this way, the cables of different coil groups in different coil layers are not connected to each other because they are in contact with the metal reference ground layer to ensure mutual insulation between the different coil groups.

[0092] By arranging the common mode filter in the manner shown in Figures 7a and 7b, the distances from all coil groups to the first and second magnetic layers are in phase and matched. Also, by arranging at least one type of metal reference ground layer, different coil groups have similar ground impedances compared to the common mode filter arranged in the manner without adding the metal reference ground layer in Figures 2a, 2b, etc. (i.e., the manner corresponding to Figures 3a, 3b, 4, etc.). This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0093] In a possible implementation, when multiple metal reference ground layers are present, the multiple metal reference ground layers are connected through reference ground holes, the reference ground holes are disposed in one or more of the first coil layer, the second coil layer, and the intermediate coil layer, and there may be one or more reference ground holes.

[0094] In this implementation, Fig. 7c is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. The difference between the common mode filter shown in Fig. 7c and the common mode filter shown in Fig. 7b and Fig. 7a is that the coil layer of the common mode filter shown in Fig. 7c is provided with reference ground holes 212. The quantity and size of the reference ground holes 212 can be set based on requirements. This is not limited in the present application. Based on the common mode filter shown in Fig. 7b and Fig. 7a, the difference between the ground impedances of different coil groups can be further reduced by providing reference ground holes.

[0095] In this implementation, the metal reference ground layer is disposed with spatial dimensions such as thickness, length, and width, which may be set based on limitations of processing technology, longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, etc. Figures 7b and 7c more clearly illustrate the location of the metal reference ground layer using only "planes" and its thickness is not shown.

[0096] FIG. 8a is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. FIG. 8b is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 8b is a cross-sectional view obtained by performing a section along the location of the dotted box region s4 in FIG. 1g. To facilitate the understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view FIG. 8b. In a possible implementation, as shown in FIG. 8a and FIG. 8b, the common mode filter may further include a third magnetic layer 13 and a fourth magnetic layer 14 parallel to each other. The first coil layer 21, the middle coil layer 23, and the second coil layer 22 are located between the third magnetic layer 13 and the fourth magnetic layer 14, the third magnetic layer 13 is perpendicular to the first magnetic layer 11 and the second magnetic layer 12, and the fourth magnetic layer 14 is perpendicular to the first magnetic layer 11 and the second magnetic layer 12.

[0097] In this implementation, the fourth magnetic layer and the third magnetic layer are arranged with spatial sizes such as thickness, length, and width, and the thickness, length, and width of the fifth magnetic layer and the sixth magnetic layer can be set based on the limitations of processing technology, longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, etc. FIG. 8a illustrates the location of the third magnetic layer and the fourth magnetic layer more clearly using only "planes", and the thickness is not shown. The material of the fourth magnetic layer and the third magnetic layer can be a magnetic material such as ferrite, and the material of the third magnetic layer and the fourth magnetic layer can be the same or different from the material of the first magnetic layer and the second magnetic layer. This is not limited in this application.

[0098] By arranging the common mode filter in the manner shown in Figures 8a and 8b, the distances from all coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer are in phase and matched. Also, compared to the common mode filter arranged in the manner shown in Figure 1h, etc., which arranges only the first magnetic layer and the second magnetic layer (as shown in Figures 2a, 2b, 4, etc.), this common mode filter allows multiple coil groups to exist in the same magnetic environment in two dimensions. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0099] FIG. 9a is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. FIG. 9b is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 9b is a cross-sectional view obtained by performing a section along the location of the dotted box region s2 in FIG. 1e. To facilitate understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in cross-sectional view 9b. In a possible implementation, as shown in FIG. 9a and FIG. 9b, when the common mode filter includes a third magnetic layer 13 and a fourth magnetic layer 14 parallel to each other, the common mode filter may further include a fifth magnetic layer 15 and a sixth magnetic layer 16 parallel to each other. The first coil layer 21, the intermediate coil layer 23, and the second coil layer 22 are located between the fifth magnetic layer 15 and the sixth magnetic layer 16, and the fifth magnetic layer 15 is perpendicular to the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, and the fourth magnetic layer 14, and the sixth magnetic layer 16 is perpendicular to the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, and the fourth magnetic layer 14.

[0100] In this implementation, the fifth and sixth magnetic layers are arranged with spatial sizes such as thickness, length, and width, and the thickness, length, and width of the fifth and sixth magnetic layers can be set based on the limitations of processing technology, longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, etc. FIG. 9a illustrates the location of the fifth and sixth magnetic layers more clearly using only "planes", and the thickness is not shown. The material of the fifth and sixth magnetic layers can be a magnetic material such as ferrite, and the material of the fifth and sixth magnetic layers can be the same or different from the material of the first, second, third, and fourth magnetic layers. This is not limited in this application.

[0101] In this implementation, the lead-out holes of the electrodes of the common mode filter may be disposed in the first magnetic layer, the second magnetic layer, the third magnetic layer, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer to facilitate the assembly and electrical connection of the common mode filter in the circuit system. Those skilled in the art may set the location, size, etc. of the lead-out holes based on the requirements. This is not limited in the present application.

[0102] By arranging the common mode filter in the manner shown in Figures 9a and 9b, the distances from all coil groups to the first magnetic layer, the second magnetic layer, the third magnetic layer, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer are in phase with each other. Also, compared to the common mode filter arranged in the manner shown in Figure 1h, etc., in which only the first magnetic layer and the second magnetic layer are arranged (as shown in Figures 2a, 2b, 4, etc.), this common mode filter allows multiple coil groups to exist in the same magnetic environment in three-dimensional space. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0103] In a possible implementation, the reference ground structure may include a metal reference ground coating layer, and the metal reference ground coating layer may coat the surface of the common mode filter. The metal reference ground coating layer is configured to coat the components included in the common mode filter in the above-mentioned specifications. By disposing the common mode filter in a manner that adds a metal reference ground coating layer, the distances from all coil groups to the magnetic layer are in phase and matched. Also, compared with the common mode filter disposed in a manner that does not dispose a metal reference ground coating layer (as shown in Figures 2a, 2b, 4, etc.), as shown in Figure 1h, etc., this common mode filter allows multiple coil groups to be in the same reference ground environment in three-dimensional space and have the same ground impedance. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0104] For example, Fig. 10a is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. Fig. 10b is a cross-sectional view of a common mode filter according to an embodiment of the present application. Fig. 10b is a cross-sectional view obtained by performing a section along the location of the dotted box area s2 in Fig. 1e (or the dotted box area s4 in Fig. 1g). To facilitate understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view 10b. In a possible implementation, as shown in Fig. 10a and Fig. 10b, a metal reference ground coating layer 71 is configured to coat the first magnetic layer 11, the second magnetic layer 12, and the multiple coil layers.

[0105] FIG. 11a is a schematic diagram of the structure of a common mode filter according to an embodiment of the present application. FIG. 11b is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 11b is a cross-sectional view obtained by performing a section along the location of the dotted box region s2 in FIG. 1e. To facilitate understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view 11b. In a possible implementation, as shown in FIG. 11a and FIG. 11b, the metal reference ground coating layer 71 is configured to coat the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, the fourth magnetic layer 14, the fifth magnetic layer 15, and the sixth magnetic layer 16, and the multiple coil layers.

[0106] In this implementation, if the reference ground structure includes parts such as a metal reference ground layer, a first auxiliary layer, and a second auxiliary layer, these parts also need to be coated with the metal reference ground coating layer 71.

[0107] In this implementation, the lead-out holes of the electrodes of the common mode filter can be disposed in the metal reference ground coating layer, the first magnetic layer 11, the second magnetic layer 12, the third magnetic layer 13, the fourth magnetic layer 14, the fifth magnetic layer 15, and the sixth magnetic layer 16 to facilitate the assembly and electrical connection of the common mode filter in the circuit system. Those skilled in the art can set the location, size, etc. of the lead-out holes based on the requirements. This is not limited in the present application.

[0108] In this implementation, the metal reference ground coating layer is provided with a thickness, and the thickness of the metal reference ground coating layer can be set based on the limitations of processing technology, longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, etc., which are not limited in this application.

[0109] FIG. 12a is a three-dimensional view of a common mode filter according to an embodiment of the present application. FIG. 12b is a main view of a common mode filter according to an embodiment of the present application. FIG. 12c is a side view of a common mode filter according to an embodiment of the present application. FIG. 12d is a top view of a common mode filter according to an embodiment of the present application. FIG. 13a is a three-dimensional view of a common mode filter according to an embodiment of the present application. FIG. 13b is a main view of a common mode filter according to an embodiment of the present application. FIG. 13c is a side view of a common mode filter according to an embodiment of the present application. FIG. 13d is a top view of a common mode filter according to an embodiment of the present application. In a possible implementation, as shown in FIG. 12a to FIG. 12d and FIG. 13a to FIG. 13d, the reference ground structure may further include (a plurality of) pads 81 and a metal reference ground piece 91 located on the surface of the common mode filter and separately connected to the terminals of each coil group. One of the two ends of the cable in the first coil layer in each coil group, which is not connected to a cable in the same coil group in another coil layer, is a terminal of the coil group. One of the two ends of the cable in the second coil layer in each coil group, which is not connected to a cable in the same coil group in another coil layer, is another terminal of the coil group. One of the two ends of the first cable in the first coil layer in the first coil group, which is not connected to the first cable in the intermediate coil layer, is a terminal of the first coil group. One of the two ends of the first cable in the second coil layer in the first coil group, which is not connected to the first cable in the intermediate coil layer, is another terminal of the first coil group.

[0110] A portion of each pad 81 is located on a first side of the common mode filter (specifically, the bottom side of the common mode filter in Figs. 12a to 12d and 13a to 13d). Another portion of each pad 81 is located on one of a plurality of second sides connected to the first side of the common mode filter (specifically, the side connected to the bottom side of the common mode filter in Figs. 12a to 12d and 13a to 13d). A metal reference ground piece 91 is located between the plurality of pads 81 and surrounds at least a portion of the first side and the second side together with the pads of the common mode filter.

[0111] In this implementation, in the example shown in Figures 12a to 12d and 13a to 13d, it is assumed that the common mode filter includes three coil groups and six pads 81, and some of the six pads 81 are located on the bottom surface (i.e., the first side) of the common mode filter, and other parts of three pads 81 (hereinafter referred to as the first group of pads) of the six pads 81 are located on the front side (i.e., the second side) connected to the bottom surface of the common mode filter. Other parts of the other three pads 81 (hereinafter referred to as the second group of pads) of the six pads 81 are located on the rear side (i.e., the second side) connected to the bottom surface of the common mode filter. As shown in Figures 12a to 12d, the metal reference ground strip 91 can be located only between the first group of pads and the second group of pads, i.e., some of the metal reference ground strip 91 is in the middle area of ​​the first side and passes through the first group of pads and the second group of pads. The other parts of the metal reference ground strip 91 are located separately on the left and right sides of the common mode filter, and the height of the parts of the metal reference ground strip 91 on the left and right sides is at least equal to the height of the pads 81 on the front and rear sides. This ensures that each pad can use the metal reference ground strip as a reference ground. As shown in Figures 13a to 13d, the metal reference ground strip 91 continues to extend based on Figures 12a to 12d, surrounding the entire common mode filter, ensuring that each pad can use the metal reference ground strip as a reference ground.

[0112] In this implementation, a metal reference ground strip is provided having a thickness and a width, and the thickness of the metal reference ground coating layer can be set based on limitations of processing technology, longitudinal transmission loss, differential mode loss, return loss, impedance indicator parameters, etc., which are not limited in this application.

[0113] By arranging the common mode filter in the manner shown in Figures 12a to 12d and 13a to 13d, the distances from all coil groups to the magnetic layers are in phase and matched. Also, compared with the common mode filter arranged in the manner shown in Figure 1h, this common mode filter allows different coil groups to have similar ground impedance at the pad position. This further improves the symmetry between different coil groups and reduces the longitudinal transmission loss of the common mode filter.

[0114] FIG. 14a is a cross-sectional view of a common mode filter according to an embodiment of the present application. FIG. 14b is a schematic diagram of multiple coil layers of a common mode filter according to an embodiment of the present application. FIG. 14a is a cross-sectional view obtained by performing a section along the location of the dotted box region s3 in FIG. 1f. To facilitate understanding of the cable layout of the coil group in the present application, only the part associated with the coil group is shown in the cross-sectional view FIG. 14a. In possible implementations, the differences between the common mode filter shown in FIG. 14a and FIG. 14b and the common mode filters in FIG. 2a and FIG. 2b, FIG. 3a and FIG. 3b, FIG. 4, FIG. 5a and FIG. 5b, FIG. 6a to FIG. 6c, FIG. 7a to FIG. 7c, FIG. 8a and FIG. 8b, FIG. 9a and FIG. 9b, FIG. 10a and FIG. 10b, FIG. 11a and FIG. 11b, FIG. 12a to FIG. 12d, and FIG. 13a to FIG. 13d are as follows: The common mode filter shown in Figures 14a and 14b includes four coil groups, the multiple coil groups further include a fourth coil group D, the multiple cable holes further include a fourth cable hole (not shown, see the cable hole configuration in Figure 2b and related description), and each fourth coil group D includes a fourth cable d in the first coil layer 21, a fourth cable d in the second coil layer 22, and a fourth cable d in the middle coil layer 23. The multiple cables of the fourth coil group D are connected through the fourth cable hole, and the first cable a, the second cable b, the third cable c, and the fourth cable d in the same coil layer are wound in parallel.

[0115] As shown in FIG. 14b, in each coil layer, the cables labeled "a", "b", "c" and "d" are the first, second, third and fourth cables of the coil layer in which the cables are located. Specifically, the first cable is labeled "a", the second cable is labeled "b", the third cable is labeled "c" and the fourth cable is labeled "d". The cables of the first coil group A are the cables labeled "a" in the first coil layer, i.e. "first layer", the middle coil layer, i.e. "second layer to fifth layer", and the second coil layer, i.e. "sixth layer". The cables of the second coil group B are the cables labeled "b" in the first coil layer, i.e. "first layer", the middle coil layer, i.e. "second layer to fifth layer", and the second coil layer, i.e. "sixth layer". The third coil group C has cables labeled "c" in the first coil layer, i.e. "1st Layer", the middle coil layer, i.e. "2nd through 5th Layer", and the second coil layer, i.e. "6th Layer". The fourth coil group D has cables labeled "d" in the first coil layer, i.e. "1st Layer", the middle coil layer, i.e. "2nd through 5th Layer", and the second coil layer, i.e. "6th Layer".

[0116] In this implementation, referring to the common mode filter shown in FIG. 14a and FIG. 14b, the four coil groups may be adjusted, another part (such as a metal reference ground coating layer) may be added, and the layout of the cables in each coil layer may be adjusted. This is not limited in this application. The number of coil groups, thickness, width, and cable spacing of the cables in the coil groups may be set based on component requirements, processing technology limitations, etc. This is not limited in this application.

[0117] By arranging the common mode filter in the manner shown in Figures 14a and 14b, the distances from all coil groups to the magnetic layers are in phase and matched. Also, compared with a common mode filter arranged in the manner of arranging only three coil groups (as shown in Figures 2a, 2b, 4, etc.) as shown in Figure 1h, etc., this common mode filter increases the number of coil groups in the common mode filter, improves the symmetry between different coil groups, and reduces the longitudinal transmission loss of the common mode filter.

[0118] The above describes the embodiments of the present application. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The embodiments and features in the embodiments in the present application may be combined with each other, provided that they are not mutually inconsistent. The selection of terms used in this specification is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

Claims

1. A common mode filter comprising: a plurality of coil groups; a plurality of cable holes; a first magnetic layer, a second magnetic layer, and a plurality of coil layers parallel to each other; the plurality of coil groups including at least a first coil group, a second coil group, and a third coil group; the plurality of cable holes including at least a first cable hole, a second cable hole, and a third cable hole; the plurality of coil layers including a first coil layer, at least one intermediate coil layer, and a second coil layer; and at least a first cable, a second cable, and a third cable disposed in each coil layer; the first coil layer, the intermediate coil layer, and the second coil layer are stacked in succession between the first magnetic layer and the second magnetic layer; the first coil group includes the first cable in each coil layer, the second coil group includes the second cable in each coil layer, and the third coil group includes the third cable in each coil layer; the first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group; At least two of the first cable, the second cable, and the third cable in the same coil layer are wound in parallel; A common mode filter, wherein the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase and matched.

2. A common mode filter comprising: a plurality of coil groups; a plurality of cable holes; a first magnetic layer, a second magnetic layer, and a plurality of coil layers parallel to each other; the plurality of coil groups including at least a first coil group, a second coil group, and a third coil group; the plurality of cable holes including at least a first cable hole, a second cable hole, and a third cable hole; the plurality of coil layers including a first coil layer, at least one intermediate coil layer, and a second coil layer; and at least a first cable, a second cable, and a third cable disposed in each coil layer; the first coil layer, the intermediate coil layer, and the second coil layer are disposed successively between the first magnetic layer and the second magnetic layer, the first coil group includes the first cable in each coil layer, the second coil group includes the second cable in each coil layer, and the third coil group includes the third cable in each coil layer; the first cable hole is configured to connect a plurality of first cables of the first coil group, the second cable hole is configured to connect a plurality of second cables of the second coil group, and the third cable hole is configured to connect a plurality of third cables of the third coil group; At least two of the first cable, the second cable, and the third cable in the same coil layer are wound in parallel, and the cable width of the same coil group is determined as follows: the first cable width and the second cable width are each a first cable width, the third cable width is a second cable width, and the first cable width is different from the second cable width; or The width of the first cable, the width of the second cable, and the width of the third cable are all different, the width of the first cable being a first cable width and the width of the second cable being a second cable width. Satisfy one of the following: A common mode filter, wherein the distances from all coil groups to the first magnetic layer and the second magnetic layer are in phase and matched.

3. The first cable width and the second cable width are 3. The common mode filter of claim 2, wherein W1 = p1 x W2 is satisfied, W1 is the first cable width, W2 is the second cable width, p1 is a ratio coefficient, and p1 ∈ [0.5, 0.8] or p1 ∈ [2, 3].

4. a first relative positional relationship exists between the first cable, the second cable, and the third cable in the first coil layer, a second relative positional relationship exists between the first cable, the second cable, and the third cable in the second coil layer, and an intermediate relative positional relationship exists between the first cable, the second cable, and the third cable in the intermediate coil layer; 4. A common mode filter as claimed in any one of claims 1 to 3, wherein the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same, and center lines of the first cable hole for connecting a first cable in an adjacent coil layer, the second cable hole for connecting a second cable in an adjacent coil layer, and the third cable hole for connecting a third cable in an adjacent coil layer are all located on the same cross section perpendicular to all coil layers.

5. a first relative positional relationship exists between the first cable, the second cable, and the third cable in the first coil layer, a second relative positional relationship exists between the first cable, the second cable, and the third cable in the second coil layer, and an intermediate relative positional relationship exists between the first cable, the second cable, and the third cable in the intermediate coil layer; A common mode filter as claimed in any one of claims 1 to 3, wherein the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are the same, and a first total length of a plurality of first cables of the first coil group, a second total length of a plurality of second cables of the second coil group, and a third total length of a plurality of third cables of the third coil group are the same.

6. a first relative positional relationship exists between the first cable, the second cable, and the third cable in the first coil layer, a second relative positional relationship exists between the first cable, the second cable, and the third cable in the second coil layer, and an intermediate relative positional relationship exists between the first cable, the second cable, and the third cable in the intermediate coil layer; A common mode filter as claimed in any one of claims 1 to 3, wherein the first relative positional relationship, the second relative positional relationship, and the intermediate relative positional relationship are different, and a first total length of a plurality of first cables of the first coil group, a second total length of a plurality of second cables of the second coil group, and a third total length of a plurality of third cables of the third coil group are the same.

7. 7. The common mode filter of claim 1, further comprising at least one reference ground structure, the reference ground structure being isolated from all of the first cables, all of the second cables, and all of the third cables, and the reference ground structure being isolated from both the first magnetic layer and the second magnetic layer.

8. the ground reference structure includes a first auxiliary layer and a second auxiliary layer; the first auxiliary layer is located between the first coil layer and the first magnetic layer, and a first reference ground cable corresponding to the first cable, the second cable, and the third cable in the first coil layer is disposed in the first auxiliary layer; 8. The common mode filter of claim 7, wherein the second auxiliary layer is located between the second coil layer and the second magnetic layer, and a second reference ground cable corresponding to the first cable, the second cable, and the third cable in the second coil layer is disposed in the second auxiliary layer.

9. the reference ground structure includes a first associated reference ground cable, an intermediate associated reference ground cable, and a second associated reference ground cable; A first associated reference ground cable of one or more first target cables of the first cable, the second cable, and the third cable in the first coil layer is disposed in the first coil layer, and the first associated reference ground cable is located on one or both sides of the first target cable; An intermediate associated reference ground cable of one or more intermediate target cables of the first cable, the second cable, and the third cable in the intermediate coil layer is disposed in the intermediate coil layer, and the intermediate associated reference ground cable is located on one or both sides of the intermediate target cable; 8. The common mode filter of claim 7, wherein a second associated reference ground cable of one or more second target cables of the first cable, the second cable, and the third cable in the second coil layer is disposed in the second coil layer, and the second associated reference ground cable is located on one or both sides of the second target cable.

10. The common mode filter of claim 9 , wherein the first associated reference ground cable, the intermediate associated reference ground cable, and the second associated reference ground cable are connected.

11. The ground reference structure comprises the following metal ground reference layers: a first metal reference ground layer located between the first coil layer and the first magnetic layer; a second metal reference ground layer located between the second coil layer and the second magnetic layer; a third metal reference ground layer located between the first coil layer and the intermediate coil layer, the third metal reference ground layer being provided with a first receiving hole for receiving a first cable hole, a second cable hole, and a third cable hole passing through the third metal reference ground layer; a fourth metal reference ground layer located between the second coil layer and the intermediate coil layer, the fourth metal reference ground layer being provided with the first cable hole, the second cable hole, and a second receiving hole for receiving the third cable hole passing through the third metal reference ground layer; an intermediate metal reference ground layer, where there are one or more intermediate metal reference ground layers, each intermediate metal reference ground layer being located between two intermediate coil layers, and a third receiving hole being provided to receive the first cable hole, the second cable hole, and the third cable hole passing through the third metal reference ground layer; 11. The common mode filter according to claim 7, comprising at least one of the following:

12. 12. The common mode filter of claim 11, wherein when multiple metal reference ground layers are present, the multiple metal reference ground layers are connected through reference ground holes, and the reference ground holes are disposed in one or more of the first coil layer, the second coil layer, and the intermediate coil layer.

13. The common mode filter further comprises a third magnetic layer and a fourth magnetic layer parallel to each other; 13. A common mode filter as claimed in any one of claims 1 to 12, wherein the first coil layer, the intermediate coil layer, and the second coil layer are located between the third magnetic layer and the fourth magnetic layer, the third magnetic layer being perpendicular to the first magnetic layer and the second magnetic layer, and the fourth magnetic layer being perpendicular to the first magnetic layer and the second magnetic layer.

14. The common mode filter further comprises a fifth magnetic layer and a sixth magnetic layer parallel to each other; 14. The common mode filter of claim 13, wherein the first coil layer, the intermediate coil layer, and the second coil layer are located between the fifth magnetic layer and the sixth magnetic layer, the fifth magnetic layer being perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer, and the sixth magnetic layer being perpendicular to the first magnetic layer, the second magnetic layer, the third magnetic layer, and the fourth magnetic layer.

15. The common mode filter according to any one of claims 7 to 12, wherein the reference ground structure includes a metal reference ground coating layer, the metal reference ground coating layer coating a surface of the common mode filter.

16. the reference ground structure includes a pad and a metal reference ground piece connected to a terminal of each coil group; a portion of each pad is located on a first side of the common mode filter, and another portion of each pad is located on one of a plurality of second sides on the common mode filter and connected to the first side; 13. A common mode filter as claimed in any one of claims 7 to 12, wherein the metal reference ground strip is located between a plurality of pads and surrounds at least a portion of the area of ​​the first side of the common mode filter and the second side having pads.

17. 4. The common mode filter of claim 1, wherein the plurality of coil groups further includes a fourth coil group, the plurality of cable holes further includes a fourth cable hole, a fourth cable is further disposed in each coil layer, the fourth coil group includes a fourth cable in each coil layer, the plurality of fourth cables of the fourth coil group are connected through the fourth cable hole, and at least two of the first cable, the second cable, the third cable, and the fourth cable in the same coil layer are wound in parallel.

18. 18. A common mode filter as claimed in any one of claims 1 to 17, wherein the first cable, the second cable, and the third cable in the same coil layer are separated by a dielectric, and different coil layers are separated by the dielectric.

19. The common mode filter according to claim 18, wherein the material of the dielectric is a ceramic material, and the material of the coil group and the cable hole is a metallic material.

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