JP6074653B2 - Common mode noise filter - Google Patents

Description

  The present invention relates to a common mode noise filter used in various electronic devices such as digital devices, AV devices, and information communication terminals.

  As shown in FIGS. 16 and 17, the conventional common mode noise filter of this type includes a rectangular parallelepiped laminated body 1, and first to sixth external electrodes 2 a to 2 f formed on the surface of the laminated body 1. The first and second coils 3 and 4, the plurality of insulator layers 5, the first to fourth capacitor electrode layers 6 a to 6 d, and the ground electrode layer 7 constituting the multilayer body 1. I was prepared. Further, the first and second external electrodes 2a and 2b are used as input terminals, the third and fourth external electrodes 2c and 2d are used as output terminals, and the first coil 3 and the second coil 4 are magnetically coupled. The common mode filter unit is configured, and the first coil 3 is connected to the first external electrode 2a as an input terminal, the third external electrode 2c as an output terminal, and the second coil 4 to the input A second external electrode 2b is connected as a terminal, and a fourth external electrode 2d is connected as an output terminal.

  The first external electrode 2a is connected to the one end 3a of the first coil 3 and the first capacitor electrode layer 6a, and the second external electrode 2b is connected to the one end 4a of the second coil 4 and the first capacitor 4a. The third external electrode 2c is connected to the other end 3b of the first coil 3 and the third capacitor electrode layer 6c, and the fourth external electrode 2d is connected to the second capacitor electrode layer 6b. The other end portion 4b of the coil 4 and the fourth capacitor electrode layer 6d were connected. Furthermore, the first to fourth capacitor electrode layers 6 a to 6 d were formed on the same insulator layer 5 and opposed to the ground electrode layer 7 with the other insulator layer 5 interposed therebetween. Thus, the capacitor C1 is formed by the first capacitor electrode layer 6a and the ground electrode layer 7, the capacitor C2 is formed by the second capacitor electrode layer 6b and the ground electrode layer 7, and the capacitor C3 is formed by the third capacitor electrode layer 6c and the ground electrode layer 7. The fourth capacitor electrode layer 6d and the ground electrode layer 7 constitute the capacitor C4. Both end portions of the ground electrode layer 7 are connected to the ground via the fifth and sixth external electrodes 2e and 2f.

  With this configuration, as shown in FIG. 18, the common mode filter unit formed by magnetically coupling the first coil 3 (L1) and the second coil 4 (L2), and the ground capacitor C1 , C3, and ground-to-ground capacitors C2 and C4, a low-pass filter (LPF) is formed, and an attenuation effect by the low-pass filter is realized not only for common mode noise but also for differential mode noise.

  As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.

JP 2009-219069 A

  In the above-described conventional common mode noise filter, the first to fourth capacitor electrode layers 6a to 6d built in order to attenuate the differential mode noise are formed on the same insulator layer 5, so that the first A first capacitor electrode layer 6a connected to one external electrode 2a (input terminal of the first coil 3), and a third capacitor electrode connected to a third external electrode 2c (output terminal of the first coil 3). Stray capacitance is generated between the second capacitor electrode layer 6c and the second capacitor electrode layer 6b connected to the second external electrode 2b (the input terminal of the second coil 4), and a fourth external electrode A stray capacitance is generated with the fourth capacitor electrode layer 6d connected to the electrode 2d (the output terminal of the second coil 4), whereby common mode noise is generated by the stray capacitance by the first coil 3, Second Easily jump over a common mode filter portion formed by-yl 4, the inherent common mode noise rejection is degraded attenuation has been a problem that can not be secured.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a common mode noise filter that can secure the attenuation of common mode noise while attenuating differential mode noise.

  In order to achieve the above object, the present invention has the following configuration.

According to a first aspect of the present invention, a common mode filter portion is formed by magnetic coupling with a plurality of insulator layers, a first coil, and the first coil formed below the first coil. A second coil to be configured; first to fourth capacitor electrode layers; first and second ground electrode layers; a laminate formed by laminating and forming these on the insulator layer; and First to sixth external electrodes formed on the surface of the laminated body, and the first and second capacitor electrode layers are formed above the first and second coils, and the first and second capacitor electrodes are formed. to form a first ground electrode layer on the second capacitor electrode layer, the first, the below the second coil 3, to form a fourth capacitor electrode layer, the third, the second ground electrode layer is formed below the fourth capacitor electrode layer, and wherein 1, the second capacitor electrode layer and the first ground electrode layer are opposed to each other, the third and fourth capacitor electrode layers are opposed to the second ground electrode layer, and one end of the first coil And the other end of the first coil is connected to the first capacitor electrode layer via the third external electrode. Then, one end of the second coil is connected to the fourth capacitor electrode layer via the second external electrode, and the other end of the second coil is connected to the fourth external electrode. The second capacitor electrode layer is connected to both ends of the first and second ground electrode layers, and the fifth and sixth external electrodes are connected. Capacitor electrode layers connected to both ends of the coil are connected to the first and second coils. The first capacitor electrode layer and the third capacitor electrode layer positioned above and below via the first and second capacitors, and the capacitor electrode layers connected to both ends of the second coil positioned vertically via the first and second coils Since the second capacitor electrode layer and the fourth capacitor electrode layer are used, the second capacitor electrode layer and the fourth capacitor electrode layer are interposed between the first capacitor electrode layer and the third capacitor electrode layer. There is almost no stray capacitance between them, which makes it difficult for common mode noise to jump over the common mode filter section formed by the first coil and the second coil. Further, the differential mode noise is attenuated by a capacitor composed of the first and second ground electrode layers and the first to fourth capacitor electrode layers connected to the ground. It has the effect that it can be made.

  According to a second aspect of the present invention, in particular, a third coil connected to the first capacitor electrode layer and the other end of the first coil above the first and second coils, The fourth coil connected to the second capacitor electrode layer and the other end of the second coil is formed. According to this configuration, the third coil and the fourth coil are connected to each other in a desired band. Since it is possible to cause series resonance between the ground and the ground, it is possible to increase the attenuation of differential mode noise and common mode noise in a desired band.

  According to a third aspect of the present invention, in particular, a fifth coil connected to the third capacitor electrode layer and one end of the first coil below the first and second coils, and a fourth coil The capacitor electrode layer and the sixth coil connected to one end of the second coil are formed. According to this configuration, the fifth coil and the sixth coil are connected to each other in the desired band. Therefore, if the frequency of the series resonance is different from the frequency of the series resonance due to the connection of the third coil and the fourth coil, the differential mode noise and the common in the two desired bands can be obtained. This has the effect of increasing the attenuation of mode noise.

According to a fourth aspect of the present invention, a common mode filter portion is formed by magnetic coupling with a plurality of insulator layers, a first coil, and the first coil formed below the first coil. A second coil to be configured; first to fourth capacitor electrode layers; first and second ground electrode layers; a laminate formed by laminating and forming these on the insulator layer; and First to sixth external electrodes formed on the surface of the laminate, and the first and second capacitor electrode layers and the first ground electrode layer above the first and second coils. And forming the third and fourth capacitor electrode layers and the second ground electrode layer below the first and second coils, and the first and second capacitor electrode layers and the The third and fourth capacitor electrodes facing the first ground electrode layer And the second ground electrode layer are opposed to each other, and one end portion of the first coil is connected to the third capacitor electrode layer via the first external electrode, and the other end of the first coil is connected. The first coil electrode layer is connected to the first capacitor electrode layer via the third external electrode, and one end of the second coil is connected to the fourth capacitor electrode layer via the second external electrode. The other end of the second coil is connected to the second capacitor electrode layer via the fourth external electrode, and both ends of the first and second ground electrode layers are connected to the fifth and fifth electrodes. A third coil connected to the first capacitor electrode layer and the other end of the first coil above the first and second coils; and A capacitor electrode layer connected to the second coil and the other end of the second coil. Forming a coil, and below the first and second coils, a fifth coil connected to the third capacitor electrode layer and one end of the first coil; a fourth capacitor electrode layer; sixth coil to form a connecting one end portion of said second coil, said first and second coils, the first to fourth capacitor electrode layer, and the third to sixth coils wherein during the first, which was to position the second ground electrode layer, according to this configuration, the first, second ground electrode layer, the third, fourth coil and the fifth, sixth Since mutual interference with the coil can be reduced, the balance degree of the differential signal is greatly improved, thereby having the effect of realizing stable differential signal quality.

According to the fifth aspect of the present invention, in particular, the first inductor connected in series with the first coil and formed between the third external electrode and the second coil are connected in series. The second inductor formed between the fourth external electrode is provided, and according to this configuration, the differential mode (differential) characteristic impedance is connected to the ground by the first and second inductors. Since it is possible to prevent the capacitor from being lowered, the differential signal loss is small and the deterioration of the signal can be prevented.

  As described above, the common mode noise filter according to the present invention forms the first and second capacitor electrode layers connected to the ground above the first and second coils, and the first and second coils. The third and fourth capacitor electrode layers connected to the ground are formed below, and the capacitor electrode layers connected to both ends of the first coil are vertically moved via the first and second coils. The first capacitor electrode layer and the third capacitor electrode layer are positioned, and the capacitor electrode layers connected to both ends of the second coil are arranged above and below the first and second coils. Since the capacitor electrode layer and the fourth capacitor electrode layer are used, there is a stray capacitance between the first capacitor electrode layer and the third capacitor electrode layer and between the second capacitor electrode layer and the fourth capacitor electrode layer. Almost never occurs. This makes it difficult for the common mode noise to jump over the common mode filter portion formed by the first coil and the second coil, so that an attenuation amount of the common mode noise can be secured, and the first and second ground electrode layers can be secured. In addition, the differential mode noise can be attenuated by the capacitor connected to the ground including the first to fourth capacitor electrode layers.

1 is an exploded perspective view of a common mode noise filter according to Embodiment 1 of the present invention. Perspective view of the common mode noise filter Circuit diagram of the common mode noise filter Comparison of frequency characteristics of common mode attenuation of the common mode noise filter and the conventional common mode noise filter The disassembled perspective view of the principal part of the common mode noise filter in Embodiment 2 of this invention Circuit diagram of the common mode noise filter Schematic diagram of another example of the common mode noise filter Comparison of frequency characteristics of differential mode attenuation between the common mode noise filter and the conventional common mode noise filter Comparison of frequency characteristics of common mode attenuation of the common mode noise filter and the conventional common mode noise filter The disassembled perspective view of the principal part of the common mode noise filter in Embodiment 3 of this invention Schematic diagram of another example of the common mode noise filter The figure which compared the frequency characteristic of the amplitude balance degree of the differential mode of the common mode noise filter and the common mode noise filter in Embodiment 1 of this invention The figure which compared the frequency characteristic of the phase balance degree of the differential mode of the common mode noise filter and the common mode noise filter in Embodiment 1 of this invention The disassembled perspective view of the principal part of the common mode noise filter in Embodiment 4 of this invention Circuit diagram of the common mode noise filter Exploded perspective view of a conventional common mode noise filter Perspective view of the common mode noise filter Circuit diagram of the common mode noise filter

(Embodiment 1)
Hereinafter, the first aspect of the present invention will be described with reference to the first embodiment.

  FIG. 1 is an exploded perspective view of a common mode noise filter according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view of the common mode noise filter.

  As shown in FIGS. 1 and 2, the common mode noise filter according to the first exemplary embodiment of the present invention includes first to ninth insulator layers 11 a to 11 i, a first coil 12, and a first coil 12. , A second coil 13 that forms a common mode filter portion by magnetic coupling with the first coil 12, first to fourth capacitor electrode layers 14 to 17, and first and second ground electrodes Layers 18 and 19, a laminated body 20 formed by laminating and forming them as insulator layers, and first to sixth external electrodes 21 a to 21 f formed on the surface of the laminated body 20 are provided. Yes.

  Then, the first and second capacitor electrode layers 14 and 15 and the first ground electrode layer 18 are formed above the first and second coils 12 and 13, and the first and second coils 12 and 13 are formed. The third and fourth capacitor electrode layers 16 and 17 and the second ground electrode layer 19 are formed below, and the first and second capacitor electrode layers 14 and 15 and the first ground electrode layer 18 are opposed to each other. The third and fourth capacitor electrode layers 16 and 17 and the second ground electrode layer 19 are opposed to each other, and the one end portion 12a of the first coil 12 is connected to the third capacitor via the first external electrode 21a. Connected to the electrode layer 16, the other end 12b of the first coil 12 is connected to the first capacitor electrode layer 14 via the third external electrode 21c, and the one end 13a of the second coil 13 is connected to the second Through the external electrode 21b of the fourth capacitor Connected to the electrode layer 17, the other end 13b of the second coil 13 is connected to the second capacitor electrode layer 15 via the fourth external electrode 21d, and the first and second ground electrode layers 18, 19 are connected. Are connected to the fifth and sixth external electrodes 21e and 21f.

  In the above configuration, the first to ninth insulator layers 11a to 11i are stacked in order from the top, and the second, fourth to sixth, and eighth insulator layers 11b, 11d to 11f, and 11h are The first, third, seventh, and ninth insulator layers 11a, 11c, 11g, and 11i are made of a magnetic material such as Cu—Ni—Zn ferrite. Each is configured in a sheet form. The number of first to ninth insulator layers 11a to 11i is not limited to the number shown in FIG.

  Further, the first coil 12 is composed of a spiral first conductor 22 and a second conductor 23, and the second coil 13 is a spiral third conductor 24 and a fourth conductor 25. It consists of

  The first to fourth conductors 22 to 25 are each formed by plating, printing, or the like with a conductive material such as silver spirally or linearly. The first conductor 22 is the upper surface of the fifth insulator layer 11e, the second conductor 23 is the upper surface of the fourth insulator layer 11d, the third conductor 24 is the upper surface of the sixth insulator layer 11f, The fourth conductors 25 are respectively formed on the upper surface of the seventh insulator layer 11g. Here, in the top view, a part of the first conductor 22 and the third conductor 24 are arranged at substantially the same position, and the winding direction is also the same direction, whereby the first conductor 22 and the third conductor The first coil 12 and the second coil 13 form a common mode filter unit that removes common mode noise.

  And the 1st conductor 22 and the 2nd conductor 23 which comprise the 1st coil 12 are connected through the via electrode 26a formed in the 4th insulator layer 11d. Further, the third conductor 24 and the fourth conductor 25 constituting the second coil 13 are connected via a via electrode 26b formed in the sixth insulator layer 11f.

  Note that the first and third conductors 22 and 24 may be spiral instead of spiral.

  The first and second capacitor electrode layers 14 and 15 are formed in a plate shape on the upper surface of the third insulator layer 11 c above the first and second coils 12 and 13.

  Furthermore, the third and fourth capacitor electrode layers 16 and 17 are formed in a plate shape on the upper surface of the eighth insulator layer 11 h below the first and second coils 12 and 13. The first to fourth capacitor electrode layers 14 to 17 may be spiral or spiral.

  The first ground electrode layer 18 is formed in a plate shape on the upper surface of the second insulator layer 11b above the first and second coils 12 and 13, and the second ground electrode layer 19 is The first and second coils 12 and 13 are formed in a plate shape on the upper surface of the ninth insulator layer 11i below the first and second coils 12 and 13.

  Here, the first to fourth capacitor electrode layers 14 to 17 and the first and second ground electrode layers 18 and 19 are provided by printing a conductive material such as silver on the upper surface of a predetermined insulator layer. . The first and second capacitor electrode layers 14 and 15 and the first ground electrode layer 18 are opposed to each other in a top view to form capacitors C1 and C2, and the third and fourth capacitor electrode layers 15 and 16 and the second ground electrode layer 19 are opposed to each other to form capacitors C3 and C4.

  Further, the first to sixth external electrodes 21 a to 21 f are formed by printing a conductor such as silver on the surface of the multilayer body 20. A nickel plating layer (not shown) is formed on these surfaces by plating, and a low melting point metal plating layer (not shown) such as tin or solder is formed on the surface of the nickel plating layer by plating. In addition, as shown in FIG. 2, the first and second external electrodes 21 a and 21 b are formed on one end surface of the multilayer body 20 to serve as input terminals, and the third and fourth external electrodes 21 c and 21 d are formed on the multilayer body 20. The output terminal is formed on the other end surface, and the fifth and sixth external electrodes 21e, 21f are formed on both side surfaces of the multilayer body 20 and are ground terminals. Further, the first external electrode 21a and the third external electrode 21c are arranged to face each other, and the second external electrode 21b and the fourth external electrode 21d are arranged to face each other.

  The first external electrode 21 a is connected to the one end 12 a of the first coil 12 and the third capacitor electrode layer 16, and the second external electrode 21 b is connected to the one end 13 a of the second coil 13 and the fourth capacitor electrode 16. The third external electrode 21 c is connected to the capacitor electrode layer 17, the other end 12 b of the first coil 12 and the first capacitor electrode layer 14, and the fourth external electrode 21 d is connected to the second coil 13. The other end portion 13b and the second capacitor electrode layer 15 are connected. The fifth and sixth external electrodes 21e and 21f are both connected to both end portions of the first and second ground electrode layers 18 and 19.

  In the common mode noise filter according to the first embodiment of the present invention, as shown in FIG. 3, the first coil 12 (L1) includes a capacitor C3 below the first coil 12 and a capacitor above the first coil 12. The structure is sandwiched between C1 and a low-pass filter is formed by C1 and C3 connected between the ground. The second coil 13 (L2) is sandwiched between a capacitor C4 below the second coil 13 and a capacitor C2 above the second coil 13, and C2 and C4 connected between the grounds. Thus, another low-pass filter is formed, so that not only common mode noise but also differential mode noise can be attenuated.

  As described above, in the common mode noise filter according to the first exemplary embodiment of the present invention, the first and second capacitor electrode layers 14 and 15 are formed above the first and second coils 12 and 13, and the first The third and fourth capacitor electrode layers 16 and 17 are formed below the first and second coils 12 and 13, and the capacitor electrode layers connected to both ends 12a and 12b of the first coil 12 are Capacitors connected to both ends 13a and 13b of the second coil 13 with the first capacitor electrode layer 14 and the third capacitor electrode layer 16 positioned above and below via the first and second coils 12 and 13, respectively. Since the electrode layers are the second capacitor electrode layer 15 and the fourth capacitor electrode layer 17 positioned above and below via the first and second coils 12 and 13, common mode noise is mutually magnetic. Since it becomes difficult to jump over the common mode filter portion formed by the first coil and the second coil that are joined, the attenuation of common mode noise can be secured, and the first to fourth connected to the ground The excellent effect that the differential mode noise can be attenuated by the capacitors C1 to C4 is obtained.

  That is, since the first capacitor electrode layer 14 and the third capacitor electrode layer 16 connected to the first coil 12 are formed on different insulator layers, stray capacitance hardly occurs between them. As a result, the capacitance component that jumps over the first coil 12 is reduced, so that the common mode noise reliably passes through the first coil 12. Since this can be applied to the second coil 13, the common mode noise attenuation can be ensured in the common mode filter section constituted by the first coil 12 and the second coil 13.

  FIG. 4 shows a comparison of the frequency characteristics of the common mode attenuation of the common mode noise filter according to the first embodiment of the present invention and the conventional common mode noise filter.

  As is clear from FIG. 4, the first embodiment of the present invention is more reliable in the frequency region of 800 MHz or higher, which is the communication frequency band of the mobile phone, as compared with the conventional case where there is a stray capacitance between the capacitor electrodes. In addition, the attenuation of common mode noise is secured.

(Embodiment 2)
The second and third embodiments of the present invention will be described below with reference to the second embodiment.

  FIG. 5 is an exploded perspective view of the common mode noise filter according to Embodiment 2 of the present invention. In the second embodiment of the present invention, components having the same configurations as those of the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted.

  The difference between the second embodiment of the present invention and the first embodiment of the present invention is that the first coil 12 and the first and second capacitor electrode layers 14 and 15 are different from each other as shown in FIG. The third coil 27 and the fourth coil 28 are formed therebetween. In FIG. 5, for the sake of simplicity of explanation, only the structure located above the fourth insulator layer 11d is shown, and the same applies to FIGS. 10 and 14 below.

  At this time, both the third coil 27 and the fourth coil 28 are spirally formed on the upper surface of the tenth insulator layer 11j. The third coil 27 is connected to the other end 12b of the first coil 12 through the second external electrode 21c, and is connected to the first capacitor electrode layer 14 through the via electrode 26c. . That is, the first capacitor electrode layer 14 is not directly connected to the external electrode, and the first coil 12, the third coil 27, and the first capacitor electrode layer 14 are sequentially connected in series. . Further, the fourth coil 28 is connected to the other end 13b of the second coil 13 through the fourth external electrode 21d, and is connected to the second capacitor electrode layer 15 through the via electrode 26d. . Similarly, the second capacitor electrode layer 15 is not directly connected to the external electrode, and the second coil 13, the fourth coil 28, and the second capacitor electrode layer 15 are connected in series in order. ing.

  As a result of forming the third coil 27 (L3) and the fourth coil 28 (L4) as described above, a schematic circuit diagram as shown in FIG. 6 is obtained.

  According to the above configuration, since the third coil 27 and the fourth coil 28 can be connected to cause series resonance between the ground in a desired band, attenuation of differential mode noise and common mode noise in the desired frequency band. The amount can be increased.

  Further, a fifth coil 29 (L5) and a sixth coil 30 (L6) may be further formed between the second coil 13 and the third and fourth capacitor electrode layers 16 and 17.

  At this time, below the first and second coils 12 and 13, the fifth coil 29 is connected to the third capacitor electrode layer 16 and one end portion 12 a of the first coil 12, and the sixth coil 30 is 7 is connected to the fourth capacitor electrode layer 17 and the one end portion 13a of the second coil 13, and a circuit schematic diagram as shown in FIG. 7 is obtained.

  According to this configuration, since the fifth coil 29 and the sixth coil 30 are connected, it is possible to cause series resonance between the ground in a desired band, and therefore, the frequency of the series resonance and the third coil 27 described above. If the series resonance frequency due to the connection of the fourth coil 28 is made different, the attenuation amounts of the differential mode noise and the common mode noise can be increased in two desired frequency bands.

  8 and 9, when the third to sixth coils 27 to 30 are formed, respectively, the differential mode attenuation of the common mode noise filter according to the second embodiment of the present invention and the conventional common mode noise filter. The frequency characteristics of the common mode attenuation amount are compared and shown.

  As is apparent from FIGS. 8 and 9, the differential mode is different from the conventional mode in two frequency bands of 800 to 900 MHz which is a frequency band of a mobile phone and 1.6 GHz to 2 GHz band which is a frequency band of GPS. A common mode attenuation can be secured.

(Embodiment 3)
The third embodiment of the present invention will be described below in particular.

  10 and 11 are exploded perspective views of the common mode noise filter according to Embodiment 3 of the present invention. In the third embodiment of the present invention, components having the same configurations as those of the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted.

  The third embodiment of the present invention is different from the second embodiment of the present invention described above in that the first and second coils 12 and 13 and the first to fourth coils as shown in FIGS. The first and second ground electrode layers 18 and 19 are located between the capacitor electrode layers 14 to 17 and the third to sixth coils 27 to 30.

  With this configuration, the first and second ground electrode layers 18 and 19 can reduce mutual interference between the third and fourth coils 27 and 28 and the fifth and sixth coils 29 and 30.

  Here, the frequency characteristic and the phase balance degree of the amplitude balance degree of the differential (differential) signal in the differential mode of the common mode noise filter according to the third embodiment of the present invention and the common mode noise filter according to the first embodiment of the present invention. FIG. 12 and FIG. 13 show comparisons of the frequency characteristics. This is the amount that shows the deviation from the balance between the positive and negative signals that make up a pair of high-speed digital differential (differential) signals. The amplitude and phase are shown as parameters. It becomes zero.

  As is clear from FIGS. 12 and 13, both the amplitude balance and the phase balance of the differential (differential) signal are particularly high as the resonance frequency is approached and in a higher frequency region than in the case of the first embodiment. As a result, stable differential signal quality can be realized.

(Embodiment 4)
Hereinafter, the invention according to the fifth aspect of the present invention will be described with reference to the fourth embodiment.

  FIG. 14 is an exploded perspective view of the common mode noise filter according to Embodiment 4 of the present invention. In the fourth embodiment of the present invention, components having the same configurations as those of the first embodiment of the present invention are denoted by the same reference numerals, and the description thereof is omitted.

  The fourth embodiment of the present invention is different from the first embodiment of the present invention described above in that the third external electrode 21c is connected in series with the first coil 12 as shown in FIGS. And a second inductor 32 connected in series with the second coil 13 and between the fourth external electrode 21d.

  In the first embodiment of the present invention and the conventional common mode noise filter, since the capacitors C1 to C4 are added between the common mode filter section and the ground, the differential mode characteristic impedance is reduced, and There is a possibility that the differential (differential) signal quality is deteriorated due to the characteristic impedance mismatch, but in the fourth embodiment, the first and second inductors 31 and 32 are further formed. The characteristic impedance of the lowered differential mode can be increased, and thereby the characteristic impedance can be within a specified range, so that the loss of differential signals is small and signal deterioration can be prevented.

  In FIG. 14, the second conductor 23 is formed in a spiral shape to form the first inductor 31. However, another conductor is formed between the first coil 12 and the third external electrode 21c. An inductor may be configured.

  In the above description, the first and second inductors 31 and 32 are formed on the output terminal (third and fourth external electrodes 21c and 21d) side of the first and second coils 12 and 13, but the input You may form in the terminal (1st, 2nd external electrode 21a, 21b) side.

  In the configurations of the second and third embodiments of the present invention, the first and second inductors 31 and 32 may be formed. In this case, it is preferable that the first and second inductors 31 and 32 and the third to sixth coils 27 to 30 are not magnetically coupled by the first and second ground electrode layers 18 and 19.

  In the first to fourth embodiments of the present invention described above, the laminate 20 may be configured upside down, and the input terminal and the output terminal may be reversed. Further, an array type in which a plurality of common mode noise filters of the present invention are arranged in parallel may be used.

  The common mode noise filter according to the present invention has an effect that the attenuation of the common mode noise can be ensured without deteriorating the characteristics of the built-in common mode filter unit while attenuating the differential mode noise. It is useful in a common mode noise filter or the like used as a noise countermeasure for various electronic devices such as information communication terminals, digital devices and AV devices.

11a to 11i First to ninth insulator layers 12 First coil 12a One end of the first coil 12b The other end of the first coil 13 Second coil 13a One end of the second coil 13b Second 14 to 17 First to fourth capacitor electrode layers 18 and 19 First and second ground electrode layers 20 Laminated bodies 21a to 21f First to sixth external electrodes 27 to 30 Third to third coils Sixth coil 31, 32 First and second inductors

Claims (5)

A plurality of insulator layers, a first coil, a second coil formed below the first coil and constituting a common mode filter unit by magnetic coupling with the first coil; 4 capacitor electrode layers, first and second ground electrode layers, a laminate formed by laminating these layers on the insulator layer, and first to first layers formed on the surface of the laminate. 6 external electrodes, the first and second capacitor electrode layers are formed above the first and second coils, and the first and second capacitor electrode layers are formed above the first and second capacitor electrode layers . Forming a ground electrode layer; forming the third and fourth capacitor electrode layers below the first and second coils; and forming the second electrode below the third and fourth capacitor electrode layers . Forming a ground electrode layer, and the first and second capacitor electrode layers; The first ground electrode layer is opposed, the third and fourth capacitor electrode layers are opposed to the second ground electrode layer, and one end of the first coil is interposed via the first external electrode. Connected to the third capacitor electrode layer, the other end of the first coil is connected to the first capacitor electrode layer via the third external electrode, and one end of the second coil Is connected to the fourth capacitor electrode layer via the second external electrode, and the other end of the second coil is connected to the second capacitor electrode layer via the fourth external electrode. A common mode noise filter in which both end portions of the first and second ground electrode layers are connected to the fifth and sixth external electrodes. Above the first and second coils, a third coil connected to the first capacitor electrode layer and the other end of the first coil, and a second capacitor electrode layer and the other end of the second coil The common mode noise filter according to claim 1, wherein a fourth coil connected to is formed. A fifth coil connected to the third capacitor electrode layer and one end of the first coil, and a fourth capacitor electrode layer and one end of the second coil are connected below the first and second coils. The common mode noise filter according to claim 2, wherein a sixth coil is formed. A plurality of insulator layers, a first coil, a second coil formed below the first coil and constituting a common mode filter unit by magnetic coupling with the first coil; 4 capacitor electrode layers, first and second ground electrode layers, a laminate formed by laminating these layers on the insulator layer, and first to first layers formed on the surface of the laminate. 6 external electrodes, and the first and second capacitor electrode layers and the first ground electrode layer are formed above the first and second coils, and the first and second coils are formed. The third and fourth capacitor electrode layers and the second ground electrode layer are formed below, and the first and second capacitor electrode layers and the first ground electrode layer are opposed to each other. 3. Pair the fourth capacitor electrode layer with the second ground electrode layer. Furthermore, one end of the first coil is connected to the third capacitor electrode layer via the first external electrode, and the other end of the first coil is connected to the third external electrode. Connected to the first capacitor electrode layer, one end of the second coil is connected to the fourth capacitor electrode layer via the second external electrode, and the other end of the second coil Is connected to the second capacitor electrode layer through the fourth external electrode, both ends of the first and second ground electrode layers are connected to the fifth and sixth external electrodes, and Above the first and second coils, a third coil connected to the first capacitor electrode layer and the other end of the first coil, the second capacitor electrode layer and the second coil Forming a fourth coil connected to the other end of the coil; Below the coil, a fifth coil connected to the third capacitor electrode layer and one end of the first coil, and a fourth coil connected to the fourth capacitor electrode layer and one end of the second coil. 6 the coil is formed of said first and second coils, the first to fourth capacitor electrode layer, said first, second ground electrode layer between the third to sixth coils Common mode noise filter with A first inductor connected in series with the first coil and formed between the third external electrode, and a second inductor formed between the second coil and connected in series with the second coil. The common mode noise filter according to claim 1, further comprising an inductor.

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