JP5439797B2 - Noise filter - Google Patents

Description

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

  As shown in FIG. 9, the conventional noise filter of this type is provided with first to fourth conductors 2a, 2b, 3a, 3b on the upper surfaces of the first to fourth insulating layers 1a to 1d, Then, the first coil 2 is formed by connecting the first conductor 2a and the spiral second conductor 2b via the via electrode 4a, and the spiral third conductor 3a and the fourth conductor are formed. 3b is connected via via electrode 4b to form second coil 3, and fifth insulating layer 5 made of a magnetic material is formed on the upper surface of fourth conductor 3b and the lower surface of first insulating layer 1a. Each was provided.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
JP 2001-76930 A

  In the conventional noise filter described above, the attenuation characteristics as shown in FIG. 11 can be obtained by combining with the capacitors 6 and 7 as shown in FIG. On the other hand, when trying to remove more noise, it is necessary to increase the impedance of the coil by increasing the number of turns of at least one of the first to fourth conductors 2a, 2b, 3a, 3b. If the impedance increases, the cut-off frequency decreases, and if the number of turns of the conductor is increased, the DC resistance component of the coil increases. Thus, when the cut-off frequency is lowered or the DC resistance component of the coil is increased, there is a problem that the loss of the signal component is increased.

  The present invention solves the above-described conventional problems, and an object of the present invention is to provide a noise filter that can remove more noise without increasing loss of signal components.

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

  According to a first aspect of the present invention, there is provided a first coil and a second coil connected to each other, a third coil and a fourth coil connected to each other, and the first to fourth coils. A first and second extraction electrodes each led out to a different side surface of the multilayer body from a connecting portion between the first coil and the second coil, the third coil, and a second coil And third and fourth extraction electrodes respectively drawn from different connection portions of the laminated body to different side surfaces of the laminated body, so that the first coil and the second coil are not magnetically coupled to each other. In addition, the third coil and the fourth coil are not magnetically coupled to each other, the first coil and the third coil are magnetically coupled, and the second coil and the fourth coil are further coupled to each other. This structure is magnetically coupled with According to this, since the capacitor can be connected to the two extraction electrodes drawn out from the connection portion between the coil and the coil, two capacitors can be combined with two coils per line, thereby reducing the impedance. More noise can be removed without increasing, and since the impedance does not increase, there is an effect that the loss of signal components does not increase.

The invention according to claim 2 of the present invention is formed on the first insulating layer, the laminated body, the first to fourth insulating layers made up of the magnetic bodies that constitute the laminated body and are sequentially laminated from the bottom. The first and second conductors, the third and fourth conductors formed in the second insulating layer, the fifth and sixth conductors formed in the third insulating layer, A seventh coil formed on a fourth insulating layer, an eighth conductor; a first coil formed by connecting the first conductor and the third conductor; the second conductor; A second coil formed by connecting a fourth conductor; a third coil formed by connecting the fifth conductor and the seventh conductor; the sixth conductor; A fourth coil formed by connecting the eighth conductor, and the first insulating layer or the second insulating layer The first coil and the second coil are connected to each other, and the first and second lead electrodes are respectively drawn out from the connecting portions to different side surfaces of the laminate, and the third insulating layer or the second coil is provided. The third coil and the fourth coil are connected to each other in four insulating layers, and third and fourth extraction electrodes are respectively drawn from the connection portions to different side surfaces of the laminate, A lead portion of the coil and the second coil is drawn out from one side surface of the laminate, and a lead portion of the third coil and the fourth coil is drawn out from the other side surface of the laminate, The second coil is not magnetically coupled to each other, the third coil and the fourth coil are not magnetically coupled to each other, and the first coil and the third coil are magnetically coupled to each other. And the second carp When the fourth and a coil which was not magnetically coupled, according to this configuration, since the same insulating layer so as to form two coils, in which effect that it is possible to thin is obtained.

  As described above, the noise filter of the present invention includes the first coil and the second coil connected to each other, the third coil and the fourth coil connected to each other, and the first to fourth coils. A laminated body provided, first and second extraction electrodes drawn from connection portions of the first coil and the second coil to different side surfaces of the laminated body, the third coil, and a fourth coil, respectively. And third and fourth extraction electrodes respectively drawn from different connection portions to the different side surfaces of the laminate, so that the first coil and the second coil are not magnetically coupled to each other. The third coil and the fourth coil are not magnetically coupled to each other, the first coil and the third coil are magnetically coupled, and the second coil and the fourth coil are Because it is magnetically coupled, Capacitors can be connected to the two extraction electrodes drawn out from the connection between the coil and the coil, so that two capacitors can be combined with two coils per line, thus increasing the impedance Therefore, it is possible to remove more noise, and since the impedance does not increase, there is an excellent effect that the loss of signal components does not increase.

  Hereinafter, a noise filter according to an embodiment of the present invention will be described with reference to the drawings.

  1 is an exploded top view of a noise filter according to an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of the noise filter, and FIG. 3 is a perspective view of the noise filter.

  As shown in FIGS. 1 to 3, the noise filter according to one embodiment of the present invention includes a laminated body 11, and first to fourth layers made of a magnetic body that constitutes the laminated body 11 and is laminated in order from the bottom. Insulating layers 12a to 12d, first and second conductors 13 and 14 formed on the first insulating layer 12a, and third and fourth conductors 15 and 14 formed on the second insulating layer 12b, 16, fifth and sixth conductors 17 and 18 formed on the third insulating layer 12c, seventh and eighth conductors 19 and 20 formed on the fourth insulating layer 12d, A first coil 21 formed by connecting the first conductor 13 and the third conductor 15, and a second coil formed by connecting the second conductor 14 and the fourth conductor 16. The coil 22, the fifth conductor 17, and the seventh conductor 19 are connected to each other. A third coil 23 formed me, in which and a fourth coil 24 formed by connecting the sixth conductor 18 and the eighth conductor 20.

  Then, the first coil 21 and the second coil 22 are connected in the second insulating layer 12b, and the first and second extraction electrodes are connected to the different side surfaces 11a and 11b of the laminated body 11 from the connection portion 25. 26a and 26b are pulled out, and the third coil 23 and the fourth coil 24 are connected in the third insulating layer 12c, and the third side 11a and 11b of the stacked body 11 is connected to the third side from the connecting portion 27. The fourth lead electrodes 28a and 28b are pulled out, respectively, and the lead portions 21a and 22a of the first coil 21 and the second coil 22 in the first insulating layer 12a are arranged on one side surface of the multilayer body 11. 11a, and the lead portions 23a and 24a of the third coil 23 and the fourth coil 24 in the fourth insulating layer 12d are connected to the other side surface 1 of the laminate 11. In which it was to withdraw from b.

  In the above configuration, the first to fourth insulating layers 12a to 12d are made of a magnetic material such as Ni-Zn ferrite, and the first insulating layer 12a, the second insulating layer 12b, and the third are formed from the bottom. The insulating layer 12c and the fourth insulating layer 12d are provided in this order.

  The first to eighth conductors 13 to 20 are formed by plating a conductive material such as silver in a spiral shape.

  In addition, a first conductor 13 and a second conductor 14 are formed on the upper surface of the first insulating layer 12a, and one end 13a of the first conductor 13 and one end 14a of the second conductor 14 are Both are exposed on one side surface 11 a of the laminate 11. That is, the lead portions 21 a and 22 a of the first coil 21 and the second coil 22 are drawn to one side surface 11 a of the laminate 11.

  Further, a third conductor 15 and a fourth conductor 16 are formed on the upper surface of the second insulating layer 12b, and the third conductor 15 and the fourth conductor 16 are connected. In this case, the second insulating layer 12b is provided with via electrodes 29a and 29b, and the third conductor 15 and the first conductor 13 are connected via the via electrode 29a. A first coil 21 is configured. Similarly, the second coil 22 is configured by connecting the fourth conductor 16 and the second conductor 14 via the via electrode 29b. Therefore, on the upper surface of the second insulating layer 12b, the first coil 21 and the second coil 22 are connected in series, and the first coil 21 and the second coil 22 connected in series are connected to each other. Thus, the first inductor portion 30a is configured.

  The first insulating layer 12a connects the first coil 21 and the second coil 22 on the top surface, and the first coil 21 and the second coil on the top surface of the second insulating layer 12b. The 22 lead portions 21 a and 22 a may be pulled out to one side surface 11 a of the laminate 11.

  With the configuration described above, a signal that has entered from the lead portion 21a of the first coil 21 (one end portion 13a of the first conductor 13) is transmitted to the lead portion 22a (second portion of the second coil 22). It will exit from one end 14a) of the conductor 14.

  The first and second lead electrodes 26a and 26b are led out from the connecting portion 25 between the first coil 21 and the second coil 22 (the third conductor 15 and the fourth conductor 16), and The first extraction electrode 26 a is exposed on one side surface 11 a of the multilayer body 11, and the second extraction electrode 26 b is exposed on the other side surface 11 b of the multilayer body 11.

  A fifth conductor 17 and a sixth conductor 18 are formed on the upper surface of the third insulating layer 12c, and the fifth conductor 17 and the sixth conductor 18 are connected. Further, third and fourth lead electrodes 28a and 28b are led out from the connecting portion 27 between the third coil 23 and the fourth coil 24 (the fifth conductor 17 and the sixth conductor 18), and The third extraction electrode 28 a is exposed on one side surface 11 a of the multilayer body 11, and the fourth extraction electrode 28 b is exposed on the other side surface 11 b of the multilayer body 11.

  In this case, the fifth conductor 17 and the third conductor 15 have substantially the same shape when viewed from above, and are provided such that current flows in the same direction when a signal is applied to the noise filter. ing. As a result, the first coil 21 and the third coil 23 are magnetically coupled. The relationship between the sixth conductor 18 and the fourth conductor 16 is also the same. In this case, the second coil 22 and the fourth coil 24 are magnetically coupled.

  Further, a seventh conductor 19 and an eighth conductor 20 are formed on the upper surface of the fourth insulating layer 12d, and one end 19a of the seventh conductor 19 and one end 20a of the eighth conductor 20 are Both are exposed on the other side surface 11 b of the laminate 11. That is, the lead portions 23 a and 24 a of the third coil 23 and the fourth coil 24 are drawn to the other side surface 11 b of the multilayer body 11. In this case, the fourth insulating layer 12d is provided with via electrodes 29c and 29d, and the seventh conductor 19 and the fifth conductor 17 are connected via the via electrode 29c. A third coil 23 is configured. Similarly, the fourth coil 24 is configured by connecting the eighth conductor 20 and the sixth conductor 18 via the via electrode 29d. Therefore, on the upper surface of the third insulating layer 12c, the third coil 23 and the fourth coil 24 are connected in series, and the third coil 23 and the fourth coil 24 connected in series are connected to each other. Thus, the second inductor portion 30b is configured.

  The fourth insulating layer 12d connects the third coil 23 and the fourth coil 24 on the upper surface, and the third coil 23 and the fourth coil 24 on the upper surface of the third insulating layer 12c. The leading portions 23 a and 24 a may be pulled out to the other side surface 11 b of the laminate 11.

  With the above-described configuration, a signal that has entered from the lead portion 23a (the one end portion 19a of the seventh conductor 19) of the third coil 23 is transmitted to the lead portion 24a (the eighth coil 24) of the fourth coil 24. It will exit from one end 20a) of the conductor 20. The arrow in FIG. 1 indicates that when a signal enters from the lead-out portion 21a of the first coil 21 and goes out from the lead-out portion 22a of the second coil 22, the signal enters from the lead-out portion 23a of the third coil 23. 4 shows the direction of signal flow when going out from the lead-out portion 24a of the fourth coil 24.

  A dummy insulating layer (not shown) made of a magnetic material is formed on the upper surfaces of the seventh conductor 19 and the eighth conductor 20.

  In addition, the spiral direction (direction from the inside of the spiral toward the outside) of the first conductor 13 and the third conductor 15 formed in the same insulating layer 12a is reversed, and the same insulating layer The direction of the spiral of the second conductor 14 and the fourth conductor 16 formed in 12b is also reversed. Therefore, when the signal that has entered from the lead portion 21a of the first coil 21 goes out from the lead portion 22a of the second coil 22, the direction of the current flowing through the first coil 21 and the second coil The direction of the current flowing through the second coil 22 is reversed, so that the direction of the magnetic flux generated in the first coil 21 is opposite to the direction of the magnetic flux generated in the second coil 22. The same applies to the fifth to eighth conductors 17 to 20, and the direction of the magnetic flux generated in the third coil 23 is opposite to the direction of the magnetic flux generated in the fourth coil 24. Further, the first to fourth coils 21 to 24 are all covered with a magnetic material, and as a result, the first coil 21 and the second coil 22 are not magnetically coupled to each other, and the third The coil 23 and the fourth coil 24 are also not magnetically coupled to each other.

  Further, as shown in FIG. 3, first to fourth external electrodes 31 a to 31 d are formed in order on one side surface 11 a of the laminate 11, and the first external electrode 31 a is a lead portion of the first coil 21. 21a (one end 13a of the first conductor 13), the second external electrode 31b to the first extraction electrode 26a, the third external electrode 31c to the third extraction electrode 28a, and the fourth external electrode 31d. Are respectively connected to the lead-out portion 22a of the second coil 22 (one end portion 14a of the second conductor 14). Furthermore, fifth to eighth external electrodes 31e to 31h are formed in this order on the other side surface 11b of the multilayer body 11, and the fifth external electrode 31e is a lead portion 23a (seventh conductor 19) of the third coil 23. The sixth external electrode 31f is connected to the fourth extraction electrode 28b, the seventh external electrode 31g is connected to the second extraction electrode 26b, and the eighth external electrode 31h is connected to the fourth coil 24. Each is connected to the lead portion 24a (one end portion 20a of the eighth conductor 20).

  As described above, in the embodiment of the present invention, the first coil 21 and the second coil 22 connected to each other, the third coil 23 and the fourth coil 24 connected to each other, First to fourth laminated bodies 11 having first to fourth coils 21 to 24 and first and second coils 22 and 22 connected to different side surfaces of the laminated body 11, respectively. Second and second extraction electrodes 26a and 26b, and third and fourth extraction electrodes 28a and 28a respectively drawn from the connecting portions 27 of the third coil 23 and the fourth coil 24 to different side surfaces of the laminate 11. 28b, so that the first coil 21 and the second coil 22 are not magnetically coupled to each other, and the third coil 23 and the fourth coil 24 are not magnetically coupled to each other. Since the first coil 21 and the third coil 23 are magnetically coupled, and the second coil 22 and the fourth coil 24 are magnetically coupled, they are pulled out from the connection portion between the coils. In addition, since two capacitors can be connected to the two extraction electrodes, and two capacitors can be combined with two coils in each of the first and second inductor portions 30a and 30b (one line), The effect that more noise can be removed without increasing the impedance can be obtained.

  Here, FIG. 4 is a diagram showing a circuit in which a capacitor is combined with a noise filter in an embodiment of the present invention, and FIG. 5 is a diagram comparing the attenuation characteristics of the noise filter of the present invention and a conventional noise filter.

  As shown in FIG. 4, two coils and two capacitors can be combined per line, that is, a combination of the first coil 21, the second coil 22, and the two capacitors 34, 35, and the third The coil 23 and the fourth coil 24 and the two capacitors 36 and 37 can be combined, so that the number of coils and capacitors forming the circuit is increased. As a result, as shown in FIG. Since the attenuation amount of the filter can be made larger than that of the conventional noise filter, more noise can be removed.

  Further, if the attenuation amount of the noise filter of the present invention is made equal to the attenuation amount of the conventional noise filter, it is only necessary to reduce the impedance of the coils 21 to 24, and the impedance of the coils 21 to 24 can be reduced. For example, since the cut-off frequency is increased and the DC resistance component can be reduced, the loss of the signal component can be reduced. That is, signal loss can be improved without deteriorating the noise removal effect.

  In addition, since the first coil 21 and the third coil 23 are magnetically coupled, and the second coil 22 and the fourth coil 24 are also magnetically coupled, the common mode impedance can be increased. Thereby, common mode noise can be removed.

  Furthermore, since two coils are formed on the top surfaces of the first to fourth insulating layers 12a to 12d, respectively, the thickness can be reduced.

  Furthermore, the first coil 21 and the second coil 22 are not magnetically coupled to each other, and the third coil 23 and the fourth coil 24 are also not magnetically coupled to each other. Mutual inductance does not occur between the coil 21 and the second coil 22 and between the third coil 23 and the fourth coil 24, respectively, thereby leading to the extraction electrodes 26a, 26b, 28a, 28b. Since no inductance is generated in the capacitor, it is possible to prevent the attenuation characteristic from changing. That is, when magnetically coupled, inductance is generated in the extraction electrodes 26a, 26b, 28a, 28b, and series resonance occurs between the inductance and the capacitor, so that the attenuation characteristic is changed.

  FIG. 6 shows a case where the first coil 21 and the second coil 22 are not magnetically coupled to each other and the third coil 23 and the fourth coil 24 are not magnetically coupled to each other (uncoupled). It is a figure which shows the attenuation | damping characteristic with the case where it couple | bonds (combination).

  As is apparent from FIG. 6, the attenuation is the largest in a predetermined frequency band when the magnetic coupling is not performed, but the frequency band in which the attenuation is the largest fluctuates when the magnetic coupling is performed.

  The two extraction electrodes 26a and 26b connected to the first inductor section 30a are extracted to different side surfaces 11a and 11b of the multilayer body 11, and the two extraction electrodes 28a and 28b connected to the second inductor section 30b are connected. 28b is also drawn to different side surfaces 11a and 11b of the multilayer body 11, so that one extraction electrode connected to the first inductor portion 30a is provided on one side surface 11a and the other side surface 11b of the multilayer body 11. Since one extraction electrode connected to the two inductor portions 30b is extracted, the capacitors can be arranged in a space-saving and symmetrical manner when the capacitors are connected to the respective extraction electrodes 26a, 26b, 28a, 28b.

  That is, as shown in FIG. 7, there is one first capacitor 32a connected to the extraction electrode of the first inductor section 30a, and second capacitor 32b connected to the extraction electrode of the second inductor section 30b. In one case, only the first capacitor 32a is arranged on one side of the noise filter 33, and only the second capacitor 32b is arranged on the other side, so the symmetry of the arrangement location of the two capacitors is not good and is useless. Space may occur. That is, since the capacitor can be connected only to the end portions of the first and second inductor portions 30a and 30b, there is a limitation on the location of the capacitor. On the other hand, in the present invention shown in FIG. 8, the first capacitor 32a and the second capacitor 32b are arranged on one side of the noise filter 33, and the first capacitor 32a and the second capacitor 32b are arranged on the other side. Therefore, the two capacitors are arranged with good symmetry, so that a useless space can be prevented. In addition, the degree of freedom in the arrangement of the capacitors is improved.

  In the noise filter according to the embodiment of the present invention described above, two inductor portions are formed, but one inductor portion may be formed. At this time, the noise filter is composed of only the first coil 21 and the second coil 22, and is drawn out from the connection portion 25 between the first coil 21 and the second coil 22 to different side surfaces of the laminate 11. The first and second extraction electrodes 26a and 26b are provided.

  Even in this configuration, since the capacitor can be connected to the two extraction electrodes 26a and 26b drawn from the connection portion 25 between the coil 21 and the coil 22, two capacitors can be combined with two coils. As a result, more noise can be removed without increasing the impedance, and since the impedance does not increase, the loss of the signal component does not increase.

  The noise filter according to the present invention has an effect that more noise can be removed without increasing loss of signal components, and in particular, various electronic devices such as digital devices, AV devices, information communication terminals, and the like. It is useful when applied to a noise filter or the like used in equipment.

The exploded top view of the noise filter in one embodiment of the present invention Equivalent circuit diagram of the same noise filter Perspective view of the noise filter The figure which shows the circuit which combines the capacitor with the same noise filter The figure which compared the attenuation characteristic of the noise filter of this invention and the conventional noise filter Diagram showing attenuation characteristics when magnetic coupling is not performed and when magnetic coupling is performed The figure which shows the arrangement | positioning relationship between the noise filter and capacitor | condenser in the case of one 1st capacitor | condenser and one 2nd capacitor | condenser The figure which shows the arrangement relation of the noise filter and the capacitor in the same noise filter Exploded perspective view of a conventional noise filter The figure which shows the circuit which combines the capacitor with the same noise filter Diagram showing the attenuation characteristics of the noise filter

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Laminated body 11a One side surface of laminated body 11b Other side surface of laminated body 12a-12d 1st-4th insulating layer 13 1st conductor 14 2nd conductor 15 3rd conductor 16 4th conductor 17 5th Conductor 18 Sixth conductor 19 Seventh conductor 20 Eighth conductor 21 First coil 21a First coil lead-out part 22 Second coil 22a Second coil lead-out part 23 Third coil 23a Third 24 coil 4a coil 24a coil extraction part 25 first coil and second coil connection part 26a first extraction electrode 26b second extraction electrode 27 third coil and third coil Connection portion of coil 4 28a Third extraction electrode 28b Fourth extraction electrode

Claims (2)

A first coil and a second coil connected to each other, a third coil and a fourth coil connected to each other, a laminate including the first to fourth coils, and the first coil And the second coil, and the first and second lead electrodes respectively drawn from the connecting portion between the second coil and the second coil, and the connecting portion between the third coil and the fourth coil. And third and fourth extraction electrodes respectively drawn on different side surfaces so as to prevent the first coil and the second coil from being magnetically coupled to each other, and the third coil and the fourth coil. Is a noise filter in which the first coil and the third coil are magnetically coupled, and the second coil and the fourth coil are magnetically coupled. A laminated body, first to fourth insulating layers made of a magnetic material that constitutes the laminated body and are sequentially laminated from the bottom; first and second conductors formed on the first insulating layer; and Third and fourth conductors formed on the second insulating layer; fifth and sixth conductors formed on the third insulating layer; and seventh and sixth conductors formed on the fourth insulating layer. An eighth conductor, a first coil formed by connecting the first conductor and the third conductor, and formed by connecting the second conductor and the fourth conductor Formed by connecting the second coil, the third coil formed by connecting the fifth conductor and the seventh conductor, and the sixth conductor and the eighth conductor. And a first coil and a second coil in the first insulating layer or the second insulating layer. And the first and second extraction electrodes respectively drawn from the connection portion to different side surfaces of the stacked body, and the third coil or the fourth coil in the third insulating layer. A fourth coil is connected, and third and fourth extraction electrodes are respectively drawn from the connection portion to different side surfaces of the laminate, and the extraction portions of the first coil and the second coil are connected to the extraction portion. Pull out from one side of the stack, and pull out the third coil and fourth coil from the other side of the stack, so that the first and second coils are not magnetically coupled to each other The third coil and the fourth coil are not magnetically coupled to each other, and the first coil and the third coil are magnetically coupled, and the second coil and the fourth coil are further coupled to each other. Magnetic coupling with the coil Noise filter.

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