JP5994108B2 - 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. 17 and 18, the conventional common mode noise filter of this type is positioned above the first coil 2 and the first coil 2 on the plurality of insulator layers 1 a constituting the multilayer body 1. And the second coil 3 is formed by connecting the first and second coil conductors 4a and 4b, and the second coil 3 is constituted by the third and fourth coil conductors 5a. 5b are connected, and the second coil conductor 4b and the third coil conductor 5a are arranged so as to be magnetically coupled to each other.

  Furthermore, first and second capacitor electrodes 6a and 6b constituting a capacitor above the second coil 3, and third and fourth capacitor electrodes 6c constituting other capacitors below the first coil 2. 6d are provided, and the first to fourth external electrodes 7a to 7d are provided on the surface of the laminate 1. Then, the first capacitor electrode 6a and the second coil conductor 4b are connected via the first external electrode 7a, and the second capacitor electrode 6b and the third coil conductor 5a are connected via the second external electrode 7b. The third capacitor electrode 6c and the first coil conductor 4a are connected via the third external electrode 7c.

  With this configuration, the fourth capacitor electrode 6d and the fourth coil conductor 5b are connected via the fourth external electrode 7d to form a common mode noise filter having two capacitors as shown in FIG. Thus, common mode noise and differential mode noise (normal mode noise) can be removed.

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

JP 2012-178718 A

  In recent high-speed digital signal transmission, various digital interfaces such as a USB to a mobile phone or the like are mounted, and noise countermeasures are desired. Particularly in mobile phones, it is desired to remove noise in the frequency band used for communication, particularly noise in the 800 to 900 MHz band, and in recent years, due to the increase in the communication frequency band, However, reduction of common mode noise and normal mode noise is desired. In other words, in the frequency characteristics of the common mode noise attenuation amount and the differential mode noise attenuation amount of the common mode noise filter, it is necessary to adjust the frequency that becomes the attenuation pole to a predetermined value.

  However, in the conventional common mode noise filter described above, the first coil conductor 4b and the fourth coil conductor 5b, the first coil conductor 4a and the third coil conductor 5a, Since magnetic coupling occurs between the coil conductor 4a and the fourth coil conductor 5b, the characteristics of each coil cannot be adjusted independently, thereby adjusting the attenuation characteristics of common mode noise and differential mode noise. Therefore, it has been difficult to adjust the frequency as the attenuation pole.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a common mode noise filter that can easily adjust a frequency serving as an attenuation pole and can attenuate not only common mode noise but also differential mode noise. To do.

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

  The invention according to claim 1 of the present invention is a laminated body, first to fourth external electrodes formed on the surface of the laminated body, and a plurality of insulating layers that constitute the laminated body and are laminated in the vertical direction. A body layer, a first coil formed of the first coil conductor and the second coil conductor formed on the insulator layer, and a third coil conductor and a fourth coil conductor formed on the insulator layer. A second coil comprising: first and second capacitor electrodes configured between the first coil conductor and the second coil conductor; the third coil conductor and the fourth coil conductor; And the third and fourth capacitor electrodes, and the first coil conductor, the second coil conductor, the third coil conductor, and the fourth coil conductor are stacked in this order. Combining the two coil conductors and the third coil conductors facing each other for magnetic coupling A mode filter portion is formed, one of the first and second capacitor electrodes is connected to a connection portion between the first coil conductor and the second coil conductor, and the other is connected to the other end of the first coil conductor. One of the third and fourth capacitor electrodes is connected to the connection portion of the third coil conductor and the fourth coil conductor, and the other is connected to the other end of the fourth coil conductor. In this configuration, the first coil conductor and the first and second capacitor electrodes form a parallel resonance circuit, and the fourth coil conductor and the third and fourth capacitor electrodes perform parallel resonance. Since the circuit part can be formed, the common mode noise is attenuated by the common mode filter part. Furthermore, the parallel resonance circuit part not only attenuates the common mode noise near the parallel resonance frequency of the circuit, but also reduces the differential mode. It can be ensured. In addition, since the magnetic coupling generated between the first to fourth coil conductors can be reduced by the first to fourth capacitor electrodes, the common mode filter section and the first coil made up of the second and third coil conductors. The characteristics of the parallel resonant circuit including the conductor or the fourth coil conductor can be adjusted independently. This makes it possible to adjust the attenuation characteristics of common mode noise and differential mode noise. This has the effect of facilitating frequency adjustment.

  According to the second aspect of the present invention, in particular, a fifth capacitor electrode is provided so as to face at least one of the third and fourth capacitor electrodes, and the fifth capacitor electrode is provided as the first coil conductor. According to this configuration, since a third capacitor is newly formed between the third and fourth capacitor electrodes and the fifth capacitor electrode, the third capacitor is used as a differential. The mode characteristic impedance can be adjusted, and this makes it possible to easily perform impedance matching in a differential (differential mode) signal transmission line, and thus has the effect of preventing deterioration of the differential signal. It is.

  According to the third aspect of the present invention, in particular, an inductor is formed between the fifth capacitor electrode and the third external electrode. According to this configuration, the fifth capacitor electrode has the fifth capacitor electrode. 3 can be provided between the differential lines. Therefore, if this series resonant circuit is adjusted to resonate at a specific frequency, a specific frequency in the differential mode noise can be obtained. This has the effect of forming an attenuation pole.

  In the invention according to claim 4 of the present invention, in particular, a fifth coil conductor connected to the second coil conductor is formed, and the fifth coil conductor is arranged so as to face the third coil conductor. Thus, according to this configuration, a series resonance circuit can be formed with the fifth coil conductor serving as the inductor section and the stray capacitance generated between the third coil conductor and the fifth coil conductor. Since the fifth coil conductor can also be used as an inductor and an electrode for generating stray capacitance, it has the effect of reducing the number of stacked layers when a series resonance circuit is provided between differential signals.

  According to the fifth aspect of the present invention, in particular, the insulator layer located on at least one of the upper and lower surfaces of the coil conductor is made of a non-magnetic material. Since the influence on the characteristics can be reduced, the frequency and the attenuation pole can be easily adjusted.

  As described above, the common mode noise filter according to the present invention includes the first and second capacitor electrodes formed between the first coil conductor and the second coil conductor, the third coil conductor, and the fourth coil conductor. Third and fourth capacitor electrodes formed between the second coil conductor and the third coil conductor, and the second coil conductor and the third coil conductor are opposed to each other and magnetically coupled to form a common mode filter portion. One of the first and second capacitor electrodes is connected to the connecting portion of the first coil conductor and the second coil conductor, the other is connected to the other end of the first coil conductor, and the third and fourth capacitors Since one of the electrodes is connected to the connection portion of the third coil conductor and the fourth coil conductor and the other is connected to the other end of the fourth coil conductor, the first coil conductor and the first, first, A parallel resonant circuit unit is formed by two capacitor electrodes, and the fourth The parallel resonance circuit section can be formed by the coil conductor and the third and fourth capacitor electrodes, thereby attenuating the common mode noise by the common mode filter section, and in the parallel resonance circuit section, near the parallel resonance frequency of the circuit In addition to the attenuation of the common mode noise, the attenuation of the differential mode can be ensured. In addition, since the magnetic coupling generated between the first to fourth coil conductors can be reduced by the first to fourth capacitor electrodes, the common mode filter section and the first coil made up of the second and third coil conductors. The characteristics of the parallel resonant circuit including the conductor or the fourth coil conductor can be adjusted independently. This makes it possible to adjust the attenuation characteristics of common mode noise and differential mode noise. This provides an excellent effect that the frequency can be easily adjusted.

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 Equivalent circuit diagram of the common mode noise filter Internal connection schematic diagram of the common mode noise filter Internal connection schematic diagram of another example of the common mode noise filter Diagram showing frequency characteristics of the common mode noise filter The disassembled perspective view of the common mode noise filter in Embodiment 2 of this invention Equivalent circuit diagram of the common mode noise filter Internal connection schematic diagram of the common mode noise filter The disassembled perspective view of the common mode noise filter in Embodiment 3 of this invention Equivalent circuit diagram of the common mode noise filter Internal connection schematic diagram of the common mode noise filter Diagram showing frequency characteristics of the common mode noise filter The disassembled perspective view of the common mode noise filter in Embodiment 4 of this invention Equivalent circuit diagram of the common mode noise filter Internal connection schematic 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 Equivalent circuit diagram of the common mode noise filter

(Embodiment 1)
The invention according to the first and fifth aspects of the present invention will be described below 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 a multilayer body 11 and first to fourth external electrodes 12 a to 12 d formed on the surface of the multilayer body 11. And the first to ninth insulator layers 13a to 13i constituting the laminate 11 and laminated in the vertical direction, and the first and fourth insulator layers 13a and 13d formed on the upper surfaces of the insulator 11 and 13d, respectively. A first coil 16 composed of one coil conductor 14 and a second coil conductor 15, and a third coil conductor 17 and a fourth coil formed on the top surfaces of the fifth and eighth insulator layers 13e and 13h, respectively. A second coil 19 comprising the first coil conductor 18, first and second capacitor electrodes 20, 21 formed between the first coil conductor 14 and the second coil conductor 15, and the third coil conductor 18. Coil conductor 17 and fourth coil conductor 18 Third constructed between, and a fourth capacitor electrodes 22 and 23.

  The first coil conductor 14, the second coil conductor 15, the third coil conductor 17, and the fourth coil conductor 18 are laminated in this order, and the second coil conductor 15 and the third coil conductor 17 are stacked. Are coupled to each other to form a common mode filter portion, the first capacitor electrode 20 is connected to the first coil conductor 14 and the second coil conductor 15, and the second capacitor electrode 21 is connected to the third capacitor electrode 21. The fourth capacitor electrode 23 is connected to the first coil conductor 14 through the external electrode 12c, the fourth capacitor electrode 23 is connected to the third coil conductor 17 and the fourth coil conductor 18, and the third capacitor electrode 22 is connected. Is connected to the fourth coil conductor 18 via the fourth external electrode 12d.

  In the above configuration, the first to ninth insulator layers 13a to 13i are stacked in this order from the bottom, and the second, third, fifth, seventh, and eighth insulator layers 13b, 13c, and 13e are stacked. , 13g, and 13h are formed in a sheet shape from a non-magnetic material such as Cu—Zn-based ceramic and glass ceramic, and the other insulator layers are formed in a sheet shape from a magnetic material such as Cu—Ni—Zn ferrite. .

  An insulator layer made of a nonmagnetic material is formed between the second coil conductor 15 and the fourth insulator layer 13d, and the nonmagnetic material is formed between the third coil conductor 17 and the sixth insulator layer 13f. An insulator layer made of a material may be formed.

  With this configuration, since the insulator layer located on at least one of the upper and lower surfaces of each coil conductor 14, 15, 17, 18 can be made of a nonmagnetic material, the influence of the magnetic material on the frequency characteristics of the coil can be reduced. This makes it easier to adjust the frequency that becomes the attenuation pole.

  Further, the first to fourth coil conductors 14, 15, 17, 18 are each formed by spirally plating or printing a conductive material such as silver. The first coil conductor 14 is the upper surface of the first insulator layer 13a, the second coil conductor 15 is the upper surface of the fourth insulator layer 13d, and the third coil conductor 17 is the fifth insulator layer 13e. And the fourth coil conductor 18 are respectively formed on the upper surface of the eighth insulator layer 13h.

  Here, a part of the second coil conductor 15 and the third coil conductor 17 are arranged at substantially the same position in the top view, and the winding direction is also made the same direction, and the second coil conductor 15 and the third coil conductor are arranged. 17 is magnetically coupled. Thereby, the common coil filter part is comprised by the 2nd coil conductor 15 and the 3rd coil conductor 17, and it can remove a common mode noise.

  The first coil conductor 14 and the second coil conductor 15 are connected to each other through the first via electrodes 24 formed in the second to fourth insulator layers 13b to 13d, respectively. The coil 16 is configured. Further, the third coil conductor 17 and the fourth coil conductor 18 are connected to each other via the second via electrode 25 formed in the sixth to eighth insulator layers 13f to 13h, and the second A coil 19 is configured. Note that the first coil 16 and the second coil 19 are differential lines.

  Here, the first via electrode 24 and the second via electrode 25 are formed by drilling holes in predetermined portions of the insulator layer with a laser and filling the holes with silver.

  The number of the first to ninth insulator layers 13a to 13i is not limited to the number shown in FIG. Further, the first to fourth coil conductors 14, 15, 17, 18 may not be spiral but may be spiral.

  Further, the first and second capacitor electrodes 20 and 21 are disposed between the first coil conductor 14 and the second coil conductor 15, and the first capacitor electrode 20 includes the second insulator layer 13 b. The second capacitor electrode 21 is formed on the upper surface of the third insulator layer 13 c located above the first capacitor electrode 20. Since the first capacitor electrode 20 and the second capacitor electrode 21 are adjacent to each other and face each other, the first capacitor electrode 20 and the second capacitor electrode 21 constitute a first capacitor 26. .

  Further, the first capacitor electrode 20 is connected to the first via electrode 24, that is, connected to the connection portion between the first coil conductor 14 and the second coil conductor 15, and the second capacitor electrode 21 is connected to the first capacitor electrode 21. It is formed so as not to be connected to one via electrode 24. Further, the second capacitor electrode 21 is connected to the first coil conductor 14 via the third external electrode 12c, and therefore the first coil conductor 14 and the first capacitor 26 are configured in parallel. .

  The third and fourth capacitor electrodes 22 and 23 are disposed between the third coil conductor 17 and the fourth coil conductor 18, and the third capacitor electrode 22 includes the sixth insulator layer 13 f. The fourth capacitor electrode 23 is formed on the upper surface of the seventh insulator layer 13 g located above the third capacitor electrode 22. Further, since the third capacitor electrode 22 and the fourth capacitor electrode 23 are adjacent to each other and face each other, the third capacitor electrode 22 and the fourth capacitor electrode 23 constitute a second capacitor 27. .

  The fourth capacitor electrode 23 is connected to the second via electrode 25, that is, connected to the connection portion between the third coil conductor 17 and the fifth coil conductor 18, and the third capacitor electrode 22 is connected to the second capacitor electrode 22. It is formed so as not to be connected to the two via electrodes 25. The third capacitor electrode 22 is connected to the fourth coil conductor 18 via the fourth external electrode 12d. Therefore, the fourth coil conductor 18 and the second capacitor 27 are configured in parallel. .

  With this configuration, a parallel resonance circuit is formed by the first coil conductor 14 and the first capacitor 26, and this parallel resonance circuit is connected between the third external electrode 12 c and the second coil conductor 15. The The fourth coil conductor 18 and the second capacitor 27 form another parallel resonance circuit, and this parallel resonance circuit is connected between the fourth external electrode 12 d and the third coil conductor 17. The

  Further, since the first and second capacitor electrodes 20 and 21 are disposed above the first coil conductor 14 in the stacking direction, the first coil conductor 14 and the second to fourth coil conductors 15, 17 and 18 are magnetically coupled. Similarly, the fourth coil conductor 18 has the third and fourth capacitor electrodes 22, 23 arranged below the stacking direction, and therefore the first to third coil conductors 14, 15 and 17 are not magnetically coupled.

  The capacitor electrodes 20 to 23 are formed in a plate shape by printing or plating a metal such as Ag. In addition, the shape may be a mesh shape or a meandering shape instead of a plate shape.

  And the laminated body 11 of a common mode noise filter is formed by the above-mentioned structure. Further, first to fourth external electrodes 12a to 12d are provided on both side surfaces of the multilayer body 11, the first external electrode 12a is the second coil conductor 15, and the second external electrode 12b is the third. The coil conductor 17 and the third external electrode 12 c are connected to the first coil conductor 14, and the fourth external electrode 12 d is connected to one end of the fourth coil conductor 18.

  Further, the first to fourth external electrodes 12a to 12d are formed by printing silver on the end face of the laminate 11, and a nickel plating layer is formed on these surfaces by plating. A low melting point metal plating layer such as tin or solder is formed on the surface of the substrate by plating.

  FIG. 3 is an equivalent circuit diagram of the common mode noise filter according to the first embodiment of the present invention.

  As is apparent from FIG. 3, the second coil conductor 15 and the third coil conductor 17 constituting the common mode filter unit are connected in series with the first coil conductor 14 and the fourth coil conductor 18, respectively. The first coil conductor 14 is connected in parallel with the first capacitor 26, and the fourth coil conductor 18 is connected in parallel with the second capacitor 27.

  In addition, the positional relationship in the stacking direction of the first to fourth coil conductors 14, 15, 17, 18 and the first to fourth capacitor electrodes 20 to 23 in the common mode noise filter according to the first embodiment of the present invention is illustrated. 4 shows.

  As described above, in the common mode noise filter according to the first exemplary embodiment of the present invention, the first and second capacitor electrodes 20 and 21 configured between the first coil conductor 14 and the second coil conductor 15. And third and fourth capacitor electrodes 22, 23 formed between the third coil conductor 17 and the fourth coil conductor 18, and the second coil conductor 15 and the third coil conductor 17. Are coupled to each other to form a common mode filter portion, the first capacitor electrode 20 is connected to the connection portion of the first coil conductor 14 and the second coil conductor 15, and the second capacitor electrode 21 is The other end of the first coil conductor 14 is connected, the fourth capacitor electrode 23 is connected to the connection portion of the third coil conductor 17 and the fourth coil conductor 18, and the third capacitor electrode 22 is connected to the fourth capacitor electrode 22. Coil guide 18 is connected to the other end of 18, and magnetic coupling generated between the first to fourth coil conductors 14, 15, 17, and 18 can be reduced by the first to fourth capacitor electrodes 20 to 23. The characteristics of the parallel resonant circuit including the common mode filter section including the second and third coil conductors 15 and 17 and the first coil conductor 14 or the fourth coil conductor 18 can be independently adjusted. This makes it possible to adjust the attenuation characteristics of common mode noise and differential mode noise, so that the effect of facilitating the adjustment of the frequency serving as the attenuation pole can be obtained.

  The first coil conductor 14 and the first and second capacitor electrodes 20 and 21 form a parallel resonance circuit unit, and the fourth coil conductor 18 and the third and fourth capacitor electrodes 22 and 23 are different from each other. A parallel resonant circuit section can be formed, which attenuates common mode noise in the common mode filter section. In addition, the parallel resonant circuit section not only attenuates common mode noise in the vicinity of the parallel resonant frequency of the circuit, but also differentials. Mode attenuation can be ensured.

  FIG. 6 shows the frequency characteristics of the differential mode and common mode of the common mode noise filter according to the first embodiment. In the present embodiment, the resonance frequency of the parallel resonance circuit composed of the first coil conductor 14 and the first capacitor 26 and the resonance frequency of the parallel resonance circuit composed of the fourth coil conductor 18 and the second capacitor 27 are determined as the main communication of the mobile phone. The shape, size, number of turns, and the like of the first and fourth coil conductors 14 and 18 and the first to fourth capacitor electrodes 20 to 23 are adjusted so that the frequency band can be set to 2 GHz. The attenuation pole of the common mode attenuation of 800 MHz to 1 GHz is due to the common mode filter portion formed by the second coil conductor 15 and the third coil conductor 17, and the attenuation pole due to the parallel resonance circuit is 2 GHz. It can be seen that it is formed not only in the common mode but also in the differential mode. As described above, it is possible to secure the common mode attenuation amount in a wide frequency band from the communication frequency band 800 MHz to 2 GHz of the mobile phone, and ensure the attenuation amount not only in the common mode but also in the differential mode at a predetermined frequency. be able to.

  In the first embodiment of the present invention described above, the second capacitor electrode 21 is positioned above the first capacitor electrode 20 and the fourth capacitor electrode 23 is positioned above the third capacitor electrode 22. However, as shown in FIG. 5, the second capacitor electrode 21 is positioned below the first capacitor electrode 20, and the fourth capacitor electrode 23 is positioned below the third capacitor electrode 22. Also good.

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

  FIG. 7 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 second embodiment of the present invention is different from the first embodiment of the present invention described above in that a fifth capacitor electrode 22 is opposed to the third capacitor electrode 22 with an insulator layer 13f as shown in FIG. The capacitor electrode 28 is provided, and the fifth capacitor electrode 28 is connected to the first coil conductor 14 via the third external electrode 12c.

  At this time, the fifth capacitor electrode 28 is formed on the upper surface of the tenth insulator layer 13j made of a nonmagnetic material formed on the upper surface of the third coil conductor 17. Further, the fifth capacitor electrode 28 and the second via electrode 25 are not connected. Furthermore, since the third capacitor electrode 22 and the fifth capacitor electrode 28 are adjacent to each other and face each other, a third capacitor 29 is provided.

  The equivalent circuit is as shown in FIG. 8, and the positional relationship in the stacking direction of the first to fourth coil conductors 14, 15, 17, 18 and the first to fifth capacitor electrodes 20 to 23, 28 is shown in FIG. become that way. That is, on the third and fourth external electrodes 12c and 12d side, the third capacitor electrode 22 and the fifth capacitor electrode 28 are provided between the first coil 16 and the second coil 19 (between the differential lines). A third capacitor 29 is formed.

  Here, in the common mode noise filter according to the first exemplary embodiment of the present invention, the first and fourth coil conductors 14 and 18 are connected in series to the common mode filter unit (second and third coil conductors 15 and 17). Therefore, there is a possibility that the characteristic impedance of the differential mode rises and deviates from the specified range. However, with this configuration, the third capacitor electrode 22 and the fifth capacitor electrode 28 are newly connected with each other. Therefore, the differential mode characteristic impedance can be lowered, and thus the differential mode characteristic impedance can be kept within a specified range. Impedance matching can be achieved and deterioration of the differential signal can be prevented.

  Note that the third capacitor 29 may be formed by making the fourth capacitor electrode 23 adjacent to and face the fifth capacitor electrode 28 instead of the third capacitor electrode 22.

  In Embodiment 2 of the present invention described above, one third capacitor 29 is provided on the third and fourth external electrodes 12c and 12d side, but the first and second external electrodes 12a, One may be provided on the 12b side, and further provided on both sides. Then, two third capacitors 29 may be configured in parallel.

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

  FIG. 10 is an exploded perspective view 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 and second embodiments of the present invention are denoted by the same reference numerals, and the description thereof is omitted.

  The third embodiment of the present invention differs from the second embodiment of the present invention described above in that an inductor 30 is provided between the fifth capacitor electrode 28 and the third external electrode 12c as shown in FIG. It is a point formed. That is, it is the inductor 30 instead of the fifth capacitor electrode 28 that is directly connected to the first coil conductor 14 via the third external electrode 12c. Further, the fifth capacitor electrode 28 and the inductor 30 are connected in series via the third via electrode 30a.

  At this time, the inductor 30 is formed on the upper surface of the eleventh insulator layer 13k made of a nonmagnetic material formed on the upper surface of the third coil conductor 17 below the fifth capacitor electrode. Further, the inductor 30 and the second via electrode 25 are not connected.

  According to this configuration, a series resonant circuit including the third capacitor 29 having the fifth capacitor electrode 28 and the inductor 30 can be provided between the differential lines. By adjusting so as to resonate at a frequency, an attenuation pole can be formed at a specific frequency in differential mode noise.

  Note that the inductor 30 may have a spiral shape, a meandering shape, or a straight shape instead of the spiral shape as shown in FIG.

  The equivalent circuit is as shown in FIG. 11, and the positional relationship of the first to fourth coil conductors 14, 15, 17, 18, the first to fourth capacitor electrodes 20 to 23, and the inductor 30 in the stacking direction is illustrated. 12 and so on. That is, a series resonance circuit including the third capacitor 29 and the inductor 30 is formed on the third and fourth external electrodes 12c and 12d side.

  FIG. 13 shows the frequency characteristics of the common mode and the differential mode in the common mode noise filter according to the third embodiment of the present invention. In the present embodiment, the resonance frequency of the parallel resonance circuit formed by the first coil conductor 14 and the first capacitor 26 and the other parallel resonance circuit formed by the fourth coil conductor 18 and the second capacitor 27 are set to The main communication frequency band is set to 2 GHz, and the resonance frequency of the series resonance circuit formed by the inductor 30 and the third capacitor 29 is set to the main communication frequency band 800 MHz of the mobile phone. As is clear from FIG. 13, in addition to the common mode and differential mode attenuation in the 2 GHz band, attenuation is secured in the differential mode even in the 800 MHz band, and excellent noise removal capability is exhibited in the common mode and the differential mode. The effect of doing.

  In the third embodiment of the present invention described above, one series resonant circuit including the third capacitor 29 and the inductor 30 is provided on the third and fourth external electrodes 12c and 12d side. One may be provided on the first and second external electrodes 12a and 12b, and one on both sides of the third and fourth external electrodes 12c and 12d and the first and second external electrodes 12a and 12b. Two in total may be provided.

  Thus, when a series resonant circuit is formed on both sides, if the two series resonant circuits have different resonant frequencies, two attenuation poles of differential mode noise can be obtained, and the differential mode noise in a wide frequency band can be reduced. Removal is possible.

  Further, the series resonance circuit is formed on one side of the first and second external electrodes 12a and 12b or the third and fourth external electrodes 12c and 12d, and another capacitor is formed on the other side. May be.

  Two series resonant circuits may be formed in parallel on one side of the first and second external electrodes 12a and 12b side or the third and fourth external electrodes 12c and 12d side.

  At this time, when the resonance frequencies of the two series resonance circuits are the same, the depth of the attenuation pole of the common mode noise increases.

  The inductor 30 and the fifth capacitor electrode 28 may be formed in the same layer.

(Embodiment 4)
The fourth embodiment of the present invention will be described below 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 differs from the first embodiment of the present invention described above in that the first coil connected to the second coil conductor 15 via the first external electrode 12a as shown in FIG. The fifth coil conductor 31 is formed, and the fifth coil conductor 31 is disposed adjacent to and opposed to the third coil conductor 17 to form the fourth capacitor 32.

  At this time, the fifth coil conductor 31 is formed on the upper surface of the tenth insulator layer 13j made of a nonmagnetic material and formed on the upper surface of the third coil conductor 17. The fifth coil conductor 31 is open at the other end and is not connected to the second via electrode 25.

  The equivalent circuit is as shown in FIG. 15, and the positional relationship in the stacking direction of the first to fifth coil conductors 14, 15, 17, 18, 31, and the first to fourth capacitor electrodes 20 to 23 is shown in FIG. Thus, stray capacitance is generated between the fifth coil conductor 31 and the third coil conductor 17 serving as the inductor portion, and thereby the fourth capacitor 32 is formed. That is, on the first and second external electrodes 12a, 12b side, a fourth capacitor is formed by a stray capacitance between the inductor section made of the fifth coil conductor 31 and the fifth coil conductor 31 serving as the inductor section. 32 is formed.

  According to this configuration, the fifth coil conductor 31 can also serve as an inductor and an electrode for generating stray capacitance, so that the number of stacked layers when a series resonance circuit is provided between differential signals can be reduced.

  Furthermore, if this series resonance circuit is adjusted to resonate at a specific frequency, an attenuation pole can be formed at a specific frequency in differential mode noise.

  Further, in the above-described fourth embodiment of the present invention, it is formed by the inductor portion composed of the fifth coil conductor 31 and the stray capacitance between the fifth coil conductor 31 and the third coil conductor 17. Although one series resonance circuit including the fourth capacitor 32 is formed, two series resonance circuits may be formed in parallel. In other words, a sixth coil conductor is separately provided, arranged opposite to the lower side of the second coil conductor 15, one end of the sixth coil conductor is connected to the second external electrode 12b, and the sixth coil conductor This is realized by setting the other end as an open end. Thereby, if two series resonance circuits are connected between the differential lines and the same resonance frequency is set, the resonance depth is increased, and the amount of attenuation in the differential mode can be increased, so that the noise removal performance is improved.

  Furthermore, in the above-described first to fourth embodiments of the present invention, a case where one common mode filter unit is provided has been described, but two or more may be provided as an array type.

  And although the common mode filter part was comprised by 2 layers of the 2nd, 3rd coil conductors 15 and 17, you may comprise by 3 or more layers.

  The common mode noise filter according to the present invention has an effect of facilitating the adjustment of the frequency serving as the attenuation pole, and is particularly used as a noise countermeasure for various electronic devices such as digital devices, AV devices, and information communication terminals. This is useful in common mode noise filters.

DESCRIPTION OF SYMBOLS 11 Laminated body 12a-12d 1st-4th external electrode 13a-13i 1st-9th insulator layer 14 1st coil conductor 15 2nd coil conductor 16 1st coil 17 3rd coil conductor 18 4th coil conductor 19 2nd coil 20-23, 28 1st-5th capacitor electrode 29 3rd capacitor 30 Inductor 31 5th coil conductor

Claims (5)

A laminated body, first to fourth external electrodes formed on a surface of the laminated body, a plurality of insulator layers that constitute the laminated body and are laminated in a vertical direction, and the insulating layer; A first coil composed of a first coil conductor and a second coil conductor; a second coil composed of a third coil conductor and a fourth coil conductor formed on the insulator layer; and the first coil First and second capacitor electrodes configured between the coil conductor and the second coil conductor, and third and fourth capacitors configured between the third coil conductor and the fourth coil conductor. A capacitor electrode; and laminating the first coil conductor, the second coil conductor, the third coil conductor, and the fourth coil conductor in this order, and the second coil conductor and the third coil conductor. Facing each other and magnetically coupling to form a common mode filter portion, One of the first and second capacitor electrodes is connected to the connection portion of the first coil conductor and the second coil conductor, the other is connected to the other end of the first coil conductor, and the third and second A common mode noise filter in which one of the four capacitor electrodes is connected to a connection portion between the third coil conductor and the fourth coil conductor, and the other is connected to the other end of the fourth coil conductor. The common mode noise filter according to claim 1, wherein a fifth capacitor electrode is provided so as to face at least one of the third and fourth capacitor electrodes, and the fifth capacitor electrode is connected to the first coil conductor. The common mode noise filter according to claim 2, wherein an inductor is formed between the fifth capacitor electrode and the third external electrode. The common mode noise filter according to claim 1, wherein a fifth coil conductor connected to the second coil conductor is formed, and the fifth coil conductor is disposed so as to face the third coil conductor. The common mode noise filter according to claim 1, wherein the insulating layer located on at least one of the upper and lower surfaces of the first to fourth coil conductors is made of a nonmagnetic material.

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