WO2009113604A1

WO2009113604A1 - Noise filter and electronic device using the same

Info

Publication number: WO2009113604A1
Application number: PCT/JP2009/054719
Authority: WO
Inventors: 弘福島
Original assignee: 株式会社村田製作所
Priority date: 2008-03-12
Filing date: 2009-03-12
Publication date: 2009-09-17

Abstract

Provided is a small-size noise filter which can remove both of a normal mode noise and a common mode noise. A common mode choke coil (L11) is formed by two coils. An LC filter (LC1) includes a coil (L1). The LC filter (LC2) includes a coil (L2). The two coils of the common mode choke coil (L11) also serve as the coils (L1, L2).

Description

Noise filter and electronic device equipped with the same

The present invention relates to a noise filter and an electronic device provided with the same, and more particularly to a noise filter including a common mode choke coil and an electronic device provided with the same.

As a noise filter for removing common mode noise, for example, a stacked common mode choke coil described in Patent Document 1 has been proposed. In the laminated common mode choke coil, the pair of coils are arranged in a state of being overlapped with each other so that the pair of coils are magnetically coupled to each other so that common mode noise can be removed.

However, the common mode choke coil can only remove common mode noise and not normal mode noise. Therefore, when it is desired to remove the normal mode noise, it is necessary to separately provide a noise removal component for removing the normal mode noise in addition to the laminated common mode choke coil. As a result, in a circuit to which the laminated common mode choke coil is applied, an increase in size becomes a problem.

Also, a differential transmission system may be used as a signal transmission system between the mobile phone driver and the receiver. In the differential transmission method, since the sum of the currents of the differential signals transmitted through the two signal lines is constant, no common mode noise is theoretically generated.

However, in practice, due to variations in driver impedance, the balance of the amplitude, rise time, phase, etc. of the two signals is lost, and common mode noise is generated in the differential signal. Therefore, it is necessary to take measures against common mode noise between the driver and the receiver.

In the differential transmission method, in order to satisfy the performance described in a standard (for example, 3GPP), higher-order (fourth or higher) harmonics of a normal mode signal constituting the differential signal may be removed. is there. That is, the normal mode signal may be regarded as normal mode noise. Therefore, it is necessary to take measures against normal mode noise between the driver and the receiver. As described above, there is a demand for a noise filter suitable for common mode noise countermeasures and normal mode noise countermeasures between mobile phone drivers and receivers.

As a conventional noise filter, for example, a multilayer array component described in Patent Document 2 is known. However, since the multilayer array component removes the same amount of normal mode noise in all frequency bands, the normal mode noise, that is, the harmonic signal constituting the differential signal is excessively removed, and the waveform quality is improved. It will be greatly reduced.
Japanese Patent Laid-Open No. 08-138938 JP 2005-64267 A

Therefore, a first object of the present invention is to provide a noise filter that can remove both normal mode noise and common mode noise and can be miniaturized.

In addition, a second object of the present invention is to provide a noise filter suitable for countermeasures against common mode noise and normal mode noise between a driver and a receiver of a mobile phone while suppressing deterioration in the quality of the differential signal waveform. It is to provide an electronic device provided.

The noise filter according to the first aspect of the present invention includes a first common mode choke coil including two coils, a first LC filter including the first coil, and a second LC including the second coil. And the two common coils of the first common mode choke coil are also used as the first coil and the second coil.

A noise filter according to a second aspect of the present invention includes a first common mode choke coil composed of two coils coupled with a coupling coefficient of 0.3 to 0.7 and a first coil including the first coil. 1 LC filter and a second LC filter including a second coil, and the two coils of the first common mode choke coil are also used as the first coil and the second coil. It is characterized by that.

An electronic apparatus according to a third aspect of the present invention includes the noise filter and a differential transmission path including a first signal line to a fourth signal line, and the first LC filter includes the first LC line The second signal line is connected between the first signal line and the second signal line, and the second LC filter is connected between the third signal line and the fourth signal line. It is characterized by.

In the electronic device according to the fourth aspect of the present invention, the noise filter, a differential transmission line including a first signal line to an eighth signal line, and the first LC filter include the first signal. The second LC filter is connected between the third signal line and the fourth signal line, and is connected between the third signal line and the second signal line. The LC filter is connected between the fifth signal line and the sixth signal line, and the fourth LC filter is connected between the seventh signal line and the eighth signal line. It is connected between them.

According to the present invention, a coaxial connector having excellent durability can be obtained.

1 is an external perspective view of a noise filter according to a first embodiment. It is an exploded view of the laminated body of the noise filter which concerns on 1st Embodiment. It is an equivalent circuit diagram of the noise filter according to the first embodiment. It is the graph which showed the relationship between the reflection characteristic of common mode noise, and a frequency. It is the graph which showed the relationship between the insertion loss of a filter with respect to normal mode noise, and a frequency. It is the graph which showed the relationship between the insertion loss of a filter with respect to normal mode noise and common mode noise, and frequency. It is the figure which showed the modification of the electrode layer for coupling | bonding. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 2nd Embodiment. It is an equivalent circuit diagram of the noise filter according to the second embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 3rd Embodiment. FIG. 6 is an equivalent circuit diagram of a noise filter according to a third embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 4th Embodiment. It is the equivalent circuit schematic of the noise filter which concerns on 4th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 5th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 6th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 7th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 8th Embodiment. FIG. 10 is an equivalent circuit diagram of a noise filter according to an eighth embodiment. It is an external appearance perspective view of the noise filter which concerns on 9th Embodiment. It is an exploded view of the laminated body of the noise filter which concerns on 9th Embodiment. It is the equivalent circuit schematic of the noise filter which concerns on 9th Embodiment. In the noise filter, when the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are 0.2, the graph shows the relationship between the filter insertion loss and the frequency with respect to the normal mode noise. is there. In the noise filter, when the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are 0.3, the graph shows the relationship between the insertion loss of the filter and the frequency with respect to the normal mode noise. is there. In the noise filter, when the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 is 0.6, a graph showing the relationship between the insertion loss of the filter and the frequency with respect to normal mode noise. is there. In the noise filter, when the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 is 0.7, the graph shows the relationship between the filter insertion loss and the frequency with respect to normal mode noise. is there. It is the graph which showed the result at the time of performing a 1st experiment in the 1st example of an experiment. It is the graph which showed the result at the time of performing a 1st experiment in the 2nd example of an experiment. It is the graph which showed the result at the time of performing a 2nd experiment in the 2nd experiment example. It is the graph which showed the result at the time of performing a 2nd experiment in the 1st experiment example. It is the graph which showed the relationship between the reflection characteristic of common mode noise, and a frequency. It is the graph which showed the relationship between the insertion loss of a filter with respect to normal mode noise, and a frequency. It is the graph which showed the relationship between the insertion loss of a filter with respect to normal mode noise and common mode noise, and frequency. It is the figure which showed the modification of the electrode layer for coupling | bonding. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 10th Embodiment. It is an equivalent circuit diagram of the noise filter according to the tenth embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 11th Embodiment. It is an equivalent circuit diagram of the noise filter according to the eleventh embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 12th Embodiment. It is an equivalent circuit schematic of the noise filter concerning a 12th embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 13th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 14th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 15th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on 16th Embodiment. It is an equivalent circuit schematic of the noise filter which concerns on 16th Embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on other embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on other embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on other embodiment. 48 is an equivalent circuit diagram of the noise filter of FIG. 47. FIG. It is a disassembled perspective view of the laminated body of the noise filter which concerns on other embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on other embodiment. It is a disassembled perspective view of the laminated body of the noise filter which concerns on other embodiment. It is a block diagram of the electronic apparatus provided with the noise filter which concerns on this invention.

Explanation of symbols

C1 to C16, C21 to C36 Capacitors CP1, CP2, CP11, CP12 Stray capacitance E1 to E20 External electrodes L1 to L4, L21 to L24 Coils L11, L12, L31, L32 Common mode choke coils LC1 to LC4, LC11 to LC14 LC filters S1 to S8 Signal lines 10a to 10h, 410a to 410n Noise filters 12a to 12h, 412a to 412n Laminated bodies 14a to 14c, 16a to 16f, 18a to 18f, 20, 22a to 22f, 24a to 24g, 26a to 26c, 414a 414c, 416a to 416f, 418a to 418f, 420, 422a to 422f, 424a to 424g, 426a to 426c Dielectric layers 30a to 30f, 34a to 34f, 38a to 38f, 42a to 42f, 430a to 43 f, 434a to 434f, 438a to 438f, 442a to 442f Coil electrode layers 32a to 32e, 36b to 36f, 40b to 40f, 44a to 44e, 432a to 432e, 436b to 436f, 440b to 440f, 444a to 444e Via conductor 50 , 52, 54, 56, 58, 60, 62, 64, 66, 68, 80, 82, 84, 86, 90, 92, 94, 96, 100, 103, 150, 152, 154, 156, 158, 160 162,164,166,168,250,252,254,256,258,260,262,264,266,268,360,362,364,366,450,452,454,456,458,460,462 , 464, 466, 468, 480, 482, 484, 486, 490, 4 2,494,496,500,503,550,552,554,556,558,560,562,564,566,568,650,652,654,656,660,662,664,666,760,762 764, 766 Capacitor electrode layers 51, 53, 55, 57, 61, 63, 65, 67, 71, 72, 73, 74, 81, 83, 85, 87, 91, 93, 95, 97, 101, 102, 104,105,151,153,155,157,161,163,165,167,171,172,173,174,251,253,255,257,261,263,265,267,361,363,365 367, 451, 453, 455, 457, 461, 463, 465, 467, 471, 472, 473, 474 481,483,485,487,491,493,495,497,501,502,504,505,551,553,555,563,563,565,567,651,653,655,657,661, 663, 665, 667, 761, 763, 765, 767 Lead portion 70, 470 Coupling electrode layer 600 Electronic device 602a, 602b Driver 604a, 604b Receiver

Hereinafter, the noise filter according to the embodiment of the present invention will be described.

(First embodiment)
FIG. 1 is an external perspective view of a noise filter 10a according to the first embodiment of the present invention. FIG. 2 is an exploded view of the multilayer body 12a of the noise filter 10a. FIG. 3 is an equivalent circuit diagram of the noise filter 10a. Hereinafter, the direction in which the ceramic green sheets are laminated when the noise filter 10a is formed is defined as the lamination direction. The stacking direction is the z-axis direction, the longitudinal direction of the noise filter 10a is the x-axis direction, and the direction orthogonal to the x-axis and the z-axis is the y-axis direction. The x-axis, y-axis, and z-axis are parallel to the sides that constitute the noise filter 10a.

(Noise filter configuration)
As shown in FIG. 1, the noise filter 10a includes a rectangular parallelepiped laminated body 12a including a plurality of LC filters and a common mode choke coil therein, and external electrodes E1 to E10 formed on the surface of the laminated body 12a. ing. Hereinafter, surfaces positioned at both ends in the x-axis direction of the stacked body 12a are defined as end surfaces, surfaces positioned at both ends in the y-axis direction of the stacked body 12a are defined as side surfaces, and upper surfaces in the z-axis direction of the stacked body 12a are defined. The surface is defined as the upper surface, and the lower surface of the laminate 12a in the z-axis direction is defined as the lower surface.

External electrodes E1, E3, E5, and E7 are each formed to extend in the z-axis direction on the side surface on the positive direction side in the y-axis direction. Each of the external electrodes E1, E3, E5, E7 functions as an input terminal. The external electrodes E2, E4, E6, E8 are each formed to extend in the z-axis direction on the negative side surface in the y-axis direction. The external electrodes E2, E4, E6, E8 each function as an output terminal. The external electrodes E9 and E10 are each formed to extend in the z-axis direction on both end faces. The external electrodes E9 and E10 each function as a ground electrode.

As will be described below, the multilayer body 12a is configured by laminating a plurality of internal electrode layers and a plurality of dielectric layers, and includes LC filters LC1 to LC4 and common mode choke coils L11 and L12 therein. ing. More specifically, as shown in FIG. 2, the multilayer body 12a includes a plurality of dielectric layers 14a to 14c, 16a, 16b, 18a to 18f, 20, 22f to 22a, 24b, 24a, 26c to 26a in this order. It is configured by being laminated. The plurality of dielectric layers 14a to 14c, 16a, 16b, 18a to 18f, 20, 22a to 22f, 24a, 24b, and 26a to 26c are rectangular insulating layers each having substantially the same area and shape.

On the main surface of the dielectric layer 16a, rectangular capacitor electrode layers 50, 52, 54, 56 having a longitudinal direction in the y-axis direction are formed. Capacitor electrode layers 50, 52, 54, and 56 are for connecting capacitor electrode layers 50, 52, 54, and 56 to external electrodes E2, E4, E6, and E8 at the ends on the negative direction side in the y-axis direction, respectively. The

drawer portions

51, 53, 55, and 57 are provided. A rectangular capacitor electrode layer 58 having a longitudinal direction in the x-axis direction is formed on the main surface of the dielectric layer 16b. The capacitor electrode layer 58 has lead

portions

71 and 72 for connecting the capacitor electrode layer 58 and the external electrodes E9 and E10 at both ends in the x-axis direction.

The capacitor electrode layer 50 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming the capacitor C1. The capacitor electrode layer 52 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming the capacitor C2. The capacitor electrode layer 54 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming the capacitor C3. The capacitor electrode layer 56 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming the capacitor C4.

Coil electrode layers 30a to 30f and 42a to 42f having shapes in which linear electrodes are bent are formed on the principal surfaces of the dielectric layers 18a to 18f, respectively. More specifically, each of the

coil electrode layers

30a and 42a has an “L” shape, and one end thereof is connected to the external electrodes E2 and E8, respectively. The coil electrode layers 30b to 30e and 42b to 42e are electrode layers formed in a spiral shape so as to rotate in opposite directions to each other formed on the same dielectric layer 18. The

coil electrode layers

30f and 42f each have an “L” shape, and one ends thereof are connected to the external electrodes E1 and E7, respectively. Furthermore, via conductors 32a to 32e and 44a to 44e connected to one ends of the coil electrode layers 30a to 30e and 42a to 42e are formed on the dielectric layers 18a to 18e, respectively. As a result, when the dielectric layers 18a to 18f are laminated, the via conductors 32a to 32e and 44a to 44e are formed on the coil electrode layers 30a to 30f and 42a to 42f formed on the adjacent dielectric layers 18a to 18f. Connect each other. As a result, the coil electrode layers 30a to 30f constitute the coil L1, and the coil electrode layers 42a to 42f constitute the coil L4.

On the main surface of the dielectric layer 24a, rectangular capacitor electrode layers 60, 62, 64, 66 having a longitudinal direction in the y-axis direction are formed. Capacitor electrode layers 60, 62, 64, and 66 are for connecting capacitor electrode layers 60, 62, 64, and 66 to external electrodes E2, E4, E6, and E8 at the negative end in the y-axis direction, respectively. The

drawer portions

61, 63, 65, and 67 are provided. A rectangular capacitor electrode layer 68 having a longitudinal direction in the x-axis direction is formed on the main surface of the dielectric layer 24b. The capacitor electrode layer 68 has lead

portions

73 and 74 for connecting the capacitor electrode layer 68 and the external electrodes E9 and E10 at both ends in the x-axis direction.

The capacitor electrode layer 60 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming the capacitor C1. The capacitor electrode layer 62 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming the capacitor C2. The capacitor electrode layer 64 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming the capacitor C3. The capacitor electrode layer 66 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming a capacitor C4.

Coil electrode layers 34a to 34f and 38a to 38f having shapes in which linear electrodes are bent are formed on the principal surfaces of the dielectric layers 22a to 22f, respectively. More specifically, the

coil electrode layers

34a and 38a each have an “L” shape, and one ends thereof are connected to the external electrodes E4 and E6, respectively. The coil electrode layers 34b to 34e and 38b to 38e are electrode layers formed on the same dielectric layer 22 in a spiral shape so as to rotate in opposite directions. The

coil electrode layers

34f and 38f each have an “L” shape, and one ends thereof are connected to the external electrodes E3 and E5, respectively. Furthermore, via conductors 36b to 36f and 40b to 40f connected to one ends of the coil electrode layers 34b to 34f and 38b to 38f are formed in the dielectric layers 22b to 22f, respectively. Thus, when the dielectric layers 22a to 22f are laminated, the via conductors 36b to 36f and 40b to 40f are formed on the coil electrode layers 34a to 34f and 38a to 38f formed on the adjacent dielectric layers 22a to 22f. Connect each other. As a result, the coil electrode layers 34a to 34f constitute the coil L2, and the coil electrode layers 38a to 38f constitute the coil L3.

Since the laminated body 12a has the above-described configuration, as shown in FIG. 3, the LC filter LC1 including the coil L1 and the capacitor C1, the LC filter LC2 including the coil L2 and the capacitor C2, the coil L3, and the capacitor C3 are included. The LC filter LC3 including the LC filter LC3 and the coil L4 and the capacitor C4 is formed. The LC filters LC2 and LC3 are not electrically connected to the LC filters LC1 and LC4. Here, taking the LC filter LC1 as an example, one end of the coil L1 is connected to the external electrode E1, and the other end of the coil L1 is connected to the external electrode E2. Furthermore, one end of the capacitor C1 is connected to the other end of the coil L1, and the other end of the capacitor C1 is connected to the external electrodes E9 and E10. The configurations of the LC filters LC2, LC3, and LC4 are the same as the configuration of the LC filter LC1, and thus the description thereof is omitted.

By the way, since the external electrodes E1 and E3 function as input terminals and the external electrodes E2 and E4 function as output terminals, in FIG. 2, for example, a current flows through the coil L1 from the bottom to the top in the z-axis direction. In the coil L2, for example, a current flows from the top to the bottom in the z-axis direction. That is, a current flows through the coil L1 and the coil L2 in the opposite directions in the z-axis direction. Furthermore, the coil electrode layers 30a to 30f constituting the coil L1 rotate clockwise as it goes from the bottom to the top in the z-axis direction, and the coil electrode layers 34a to 34f constituting the coil L2 are rotated in the z-axis direction. It turns counterclockwise as it goes from bottom to top. That is, the coil L1 and the coil L2 are rotated in opposite directions. Therefore, when current flows through the coil L1 and the coil L2, the current turns in the same direction. Furthermore, as shown in FIG. 2, the coil L1 and the coil L2 are arranged side by side in the z-axis direction so that the coil axis of the coil L1 and the coil axis of the coil L2 substantially coincide. As a result, the coil L1 and the coil L2 generate magnetic fluxes in the same direction and are magnetically coupled, so that the coils constituting the LC filter LC1 and LC filter LC2 and the two constituting the common mode choke coil L11 It comes to share with the coil. In particular, the coil L1 and the coil L2 are magnetically coupled in the vicinity of the other end (the central portion in the z-axis direction in FIG. 2) with respect to the end where the capacitors C1 and C2 are connected. The coil L3 and the coil L4 are also magnetically coupled to serve as both the coil constituting the LC filter LC3 and the LC filter LC4 and the two coils constituting the common mode choke coil L12. For details, see the coil L1. Since it is the same as that of the coil L2, description thereof is omitted.

Furthermore, a coupling electrode layer 70 for capacitively coupling the coil L1 and the coils L3 and L4 is formed on the main surface of the dielectric layer 20 disposed between the dielectric layer 18f and the dielectric layer 22f. Yes. The coupling electrode layer 70 is capacitively coupled to the coil L2 and the coils L3 and L4. Similarly, the coupling electrode layer 70 is capacitively coupled to the coils L1 and L2 for the coils L3 and L4. Therefore, the coupling electrode layer 70 is formed across the LC filter LC1 and the LC filters LC3 and LC4 when viewed in plan from the z-axis direction. Similarly, the coupling electrode layer 70 is formed across the LC filter LC2 and the LC filters LC3 and LC4 when viewed in plan from the z-axis direction.

Here, the coupling electrode layer 70 has a shape in which two annular linear electrodes are connected. This is to prevent the coupling electrode layer 70 from interfering with the magnetic flux generated in the coils L1 to L4 when a current flows through the coils L1 to L4.

(effect)
As described above, according to the noise filter 10a, the LC filters LC1 to LC4 are incorporated, and the coils L1 to L4 also serve as the coils constituting the common mode choke coils L11 and L12. Both common mode noises can be removed.

Also, according to the noise filter 10a, the LC filter and the common mode choke coil are built in one noise filter 10a, and therefore the LC filter and the common mode choke coil are configured by separate electronic components. As a result, the entire circuit can be reduced in size. In particular, in the noise filter 10a, the coils L1 and L2 function as coils constituting the common mode choke coil L11 and also function as part of the LC filters LC1 and LC2. Similarly, the coils L3 and L4 function as coils constituting the common mode choke coil L12 and also function as part of the LC filters LC3 and LC4. As described above, in the noise filter 10a, the coils L1 to L4 are also used as a part of the LC filter and a part of the common mode choke coil, so that the noise filter 10a is further downsized.

Also, the noise filter 10a can efficiently remove common mode noise as described below. In the xz cross section, when the magnetic flux generated by the coil L1 and the magnetic flux generated by the coil L2, and the magnetic flux generated by the coil L1 and the magnetic flux generated by the coil L2 are not equal, normal mode noise is converted into common mode noise. As a result, new common mode noise is generated, and the common mode noise is not efficiently removed. Therefore, in the noise filter 10a, the current paths of the coils L1 and L2 are configured so that the magnitude of the magnetic flux generated by the coil L1 and the magnitude of the magnetic flux generated by the coil L2 are substantially equal in the xz section. Similarly, in the xz cross section, the current path is configured so that the magnitude of the magnetic flux generated by the coil L3 and the magnitude of the magnetic flux generated by the coil L4 are substantially equal. Thereby, the difference in characteristics between the coil L1 and the coil L2 and between the coil L3 and the coil L4 can be reduced. Therefore, normal mode noise is not converted into common mode noise, and new common mode noise is not generated. Therefore, in the noise filter 10a, common mode noise can be more efficiently removed by the common mode choke coil L11 and the common mode choke coil L12.

In addition, when the capacitor electrode is not line symmetric with respect to the dielectric layer 20 in the xz cross section, the magnitude of the magnetic flux is difficult to equalize, so normal mode noise is converted into common mode noise, and a new common Mode noise occurs and common mode noise is not efficiently removed. On the other hand, as shown in FIG. 2, the capacitor electrode layers 50, 52, 58, 60, 62, and 68 have boundary lines between the LC filter LC1 and the LC filter LC2 (dielectric layer 20 in FIG. 2) in the xz section. On the other hand, it has a substantially line-symmetric structure. Similarly, as shown in FIG. 2, the capacitor electrode layers 54, 56, 58, 64, 66, 68 have boundaries between the LC filter LC 3 and the LC filter LC 4 (dielectric layer 20 in FIG. 2) in the xz section. On the other hand, it has a substantially line-symmetric structure. Thereby, the influence which

capacitor electrode layer

50,52,58 has on the magnetic flux by coil L1, and the influence which

capacitor electrode layer

60,62,68 has on the magnetic flux by coil L2 can be made equal. Similarly, the influence of the capacitor electrode layers 54, 56, and 58 on the magnetic flux by the coil L4 can be made equal to the influence of the capacitor electrode layers 64, 66, and 68 on the magnetic flux by the coil L3. That is, the difference in characteristics between the coil L1 and the coil L2 and between the coil L3 and the coil L4 can be further reduced. Therefore, normal mode noise is not converted into common mode noise, and new common mode noise is not generated. Therefore, in the noise filter 10a, common mode noise can be more efficiently removed by the common mode choke coil L11 and the common mode choke coil L12.

In general, to increase the noise suppression effect, the insertion loss characteristic may be increased. However, in order to further increase the effect, it is important to suppress the reflection of the noise and to reduce the reflection against the noise. It becomes. In the noise filter 10a, the common mode choke coil L11 and the common mode choke coil L12 are capacitively coupled to generate noise circulation between the common mode choke coils L11 and L12, thereby reducing reflection. FIG. 4 is a graph showing the relationship between the reflection characteristic of common mode noise and the frequency. The vertical axis represents the reflection characteristics, and the horizontal axis represents the frequency. On the vertical axis in the graph, 0 db indicates total reflection.

As shown in FIG. 2, in the noise filter 10a, a coupling electrode layer 70 is provided. The coupling electrode layer 70 capacitively couples a set of coils L1 and L2 and a set of coils L3 and L4. As a result, as shown in the graph of FIG. 4, the noise filter 10 a can suppress the reflection of the common mode noise more than the noise filter without the coupling electrode layer 70. Incidentally, when there is no coupling electrode layer 70, for example, the coupling capacitance between the coil L1 and the coil L3 is about 0.5 pF, but when there is the coupling electrode layer 70, the coil L1 and the coil L3. And the coupling capacitance is about 5 pF. As shown in FIG. 2, all of the coils L1 to L4 may be capacitively coupled, or three or two of the coils L1 to L4 may be capacitively coupled. However, when the two coils are capacitively coupled, one of the coils L1 and L2 and one of the coils L3 and L4 need to be capacitively coupled.

In the noise filter 10a, the coil electrode layers 30a to 30f, 34a to 34f, the capacitor electrode layers 50, 52, 58, 60, 62, and 68, and the dielectric layers 16a, 16b, 18a to 18f, 22a to 22f, As shown in FIG. 2, the coils 24a and 24b are stacked such that the coils L1 and L2 are positioned between the capacitors C1 and C2 in the z-axis direction. That is, no capacitor is provided between the coil L1 and the coil L2. Therefore, the magnetic flux generated in the coil L1 and the coil L2 is not easily disturbed by the capacitors C1 and C2. As a result, the magnetic flux in the coils L1 and L2 can be increased, the normal mode noise removal characteristics of the LC filters LC1 and LC2 can be improved, and the magnetic coupling between the LC filter LC1 and the LC filter LC2 is increased. Therefore, the common mode noise removal characteristics of the common mode choke coil L11 can be improved. The same applies to the LC filters LC3 and LC4 and the coils L3 and L4.

Incidentally, the noise filter 10a generates stray capacitances CP1 and CP2 as shown in FIG. The stray capacitance CP1 is generated between the coil L1 and the coil L2 and between the coil L3 and the coil L4 by overlapping the coil electrode layer 30, the coil electrode layer 34, the coil electrode 38, and the coil electrode 42 in the z-axis direction. Stray capacitance. Since the stray capacitance CP1 is generated, the normal mode noise of the noise filter 10a can be efficiently removed and the change in the insertion loss of the filter with respect to the normal mode noise is steep as described below with reference to FIG. Can be.

The stray capacitance CP2 is a stray capacitance generated at both ends of the coils L1 to L4 by overlapping the coil electrode layers 30, 34, 38, and 42 in the z-axis direction. Since the stray capacitance CP2 is generated, the cutoff frequency of normal mode noise and common mode noise can be lowered and the filter for normal mode noise and common mode noise can be reduced, as will be described below with reference to FIG. The change in insertion loss can be made steep. 5 and 6 are graphs showing the relationship between filter insertion loss and frequency for normal mode noise and common mode noise. The vertical axis represents insertion loss, and the horizontal axis represents frequency.

First, the effect produced by the stray capacitance CP1 will be described. FIG. 5 shows the insertion loss of the filter for normal mode noise when it is assumed that there is a stray capacitance CP1, and the insertion loss of the filter for normal mode noise when it is assumed that there is no stray capacitance CP1. Since common mode noise is not affected by stray capacitance CP1, common mode insertion loss is not shown in FIG.

As shown in FIG. 3, when the stray capacitance CP1 is generated, the coils L1 and L2 and the stray capacitance CP1 constitute an LC filter. Therefore, when the stray capacitance CP1 is generated, the normal mode noise at the resonance point on the high frequency side can be efficiently removed as shown in FIG. 5 compared to the case where the stray capacitance CP1 is not generated. Further, when the stray capacitance CP1 is generated, the insertion loss of the filter with respect to the normal mode noise at the resonance point on the high frequency side is abruptly changed as compared with the case where the stray capacitance CP1 is not generated as shown in FIG.

Next, the effect produced by the stray capacitance CP2 will be described. FIG. 6 shows filter insertion loss for normal mode noise and common mode noise when it is assumed that there is a stray capacitance CP2, and insertion of a filter for normal mode noise and common mode noise when there is no stray capacitance CP2. Loss is shown.

When the stray capacitance CP2 is generated, as compared with the case where the stray capacitance CP2 is not generated, the frequencies of the resonance points of the normal mode noise and the common mode noise are lower as shown in FIG. That is, when the stray capacitance CP2 is generated, the cut-off frequency becomes lower than when the stray capacitance CP2 is not generated. Furthermore, when the stray capacitance CP2 is generated, the normal mode noise and the common mode insertion loss at the resonance point on the high frequency side are sharply changed as shown in FIG. 6 as compared with the case where the stray capacitance CP2 is not generated.

(Modification)
In the noise filter 10a shown in FIG. 2, the coupling electrode layer 70 has a shape in which two annular linear electrodes are connected, but the shape of the coupling electrode layer 70 is not limited to this. The coupling electrode layer 70 only needs to have a shape that does not interfere with the magnetic flux generated in the coils L1 to L4. In other words, the coupling electrode layer 70 only needs to be formed so as not to overlap the coils L1 to L4 when viewed in plan from the z-axis direction. Therefore, the coupling electrode layer 70 may have a shape as a modification of the coupling electrode layer 70 shown in FIGS. 7 (a) to 7 (g). The coupling electrode layer 70 may be a solid pattern electrode as shown in FIG. Since the coupling electrode layer 70 shown in FIG. 7G is not grounded, it does not affect the magnetic coupling.

(Second Embodiment)
The configuration of the noise filter 10b according to the second embodiment will be described below with reference to the drawings. FIG. 8 is an exploded perspective view of the multilayer body 12b of the noise filter 10b according to the second embodiment. FIG. 9 is an equivalent circuit diagram of the noise filter 10b. 8 and 9, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals.

As shown in FIG. 8, the laminated body 12b has a structure in which capacitor electrode layers 80, 82, 84, 86, 90, 92, 94, and 96 are formed on the dielectric layers 16a and 24a, respectively. Is different. Hereinafter, the description will focus on the differences between the laminate 12b and the laminate 12a.

Capacitor electrode layers 50, 52, 54, 56, 80, 82, 84, 86 are formed on the dielectric layer 16a. The capacitor electrode layer 80 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming a capacitor C5. The capacitor electrode layer 82 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming a capacitor C6. The capacitor electrode layer 84 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming a capacitor C7. The capacitor electrode layer 86 and the capacitor electrode layer 58 are opposed to each other with the dielectric layer 16a interposed therebetween, thereby forming a capacitor C8.

Furthermore, a lead-out portion 81 is provided at the end of the capacitor electrode layer 80 on the positive side in the y-axis direction. Accordingly, as shown in FIG. 9, the capacitor C5 is connected between the external electrode E1 and the external electrodes E9 and E10. A lead-out portion 83 is provided at the end of the capacitor electrode layer 82 on the positive side in the y-axis direction. Thereby, as shown in FIG. 9, the capacitor C6 is connected between the external electrode E3 and the external electrodes E9 and E10. A lead-out portion 85 is provided at the end of the capacitor electrode layer 84 on the positive side in the y-axis direction. Accordingly, as shown in FIG. 9, the capacitor C7 is connected between the external electrode E5 and the external electrodes E9 and E10. A lead-out portion 87 is provided at the end of the capacitor electrode layer 86 on the positive side in the y-axis direction. Accordingly, as shown in FIG. 9, the capacitor C8 is connected between the external electrode E7 and the external electrodes E9 and E10.

Capacitor electrode layers 60, 62, 64, 66, 90, 92, 94, and 96 are formed on the dielectric layer 24a. The capacitor electrode layer 90 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming a capacitor C5. The capacitor electrode layer 92 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming a capacitor C6. The capacitor electrode layer 94 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming a capacitor C7. The capacitor electrode layer 96 and the capacitor electrode layer 68 are opposed to each other with the dielectric layer 24b interposed therebetween, thereby forming a capacitor C8.

Furthermore, a lead-out portion 91 is provided at the end of the capacitor electrode layer 90 on the positive side in the y-axis direction. Accordingly, as shown in FIG. 9, the capacitor C5 is connected between the external electrode E1 and the external electrodes E9 and E10. A lead-out portion 93 is provided at the end of the capacitor electrode layer 92 on the positive side in the y-axis direction. Thereby, as shown in FIG. 9, the capacitor C6 is connected between the external electrode E3 and the external electrodes E9 and E10. A lead-out portion 95 is provided at the end of the capacitor electrode layer 94 on the positive side in the y-axis direction. Accordingly, as shown in FIG. 9, the capacitor C7 is connected between the external electrode E5 and the external electrodes E9 and E10. A lead-out portion 97 is provided at the end of the capacitor electrode layer 96 on the positive side in the y-axis direction. Accordingly, as shown in FIG. 9, the capacitor C8 is connected between the external electrode E7 and the external electrodes E9 and E10.

The noise filter 10b is added with capacitors C5 to C8 and has a saddle type structure, so that the insertion loss of the filter with respect to normal mode noise and common mode noise can be increased sharply.

(Third embodiment)
The configuration of the noise filter 10c according to the third embodiment will be described below with reference to the drawings. FIG. 10 is an exploded perspective view of the multilayer body 12c of the noise filter 10c according to the third embodiment. FIG. 11 is an equivalent circuit diagram of the noise filter 10c. 10 and 11, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals.

As shown in FIG. 10, the laminated body 12c is different from the laminated body 12a shown in FIG. 2 in that

dielectric layers

16c and 24c are provided instead of the

dielectric layers

16a, 16b, 24a and 24b. . Hereinafter, the difference between the stacked body 12c and the stacked body 12a will be mainly described.

In the noise filter 10b, as shown in FIG. 10,

dielectric layers

16c and 24c formed with capacitor electrode layers 100 and 103 are inserted in the middle of the coils L1, L2, L3, and L4. More specifically, the dielectric layer 16c is disposed between the dielectric layer 18c and the dielectric layer 18d. The dielectric layer 24c is disposed between the dielectric layer 22c and the dielectric layer 22d. Capacitor electrode layers 100 and 103 (grounding electrodes) have blank portions where no electrode layers are formed so as not to overlap with the coil axes of coils L1 to L4 when viewed in plan from the z-axis direction. . The via

conductors

32c, 36d, 40d, and 44c penetrate through the blank portion so as not to contact the capacitor electrode layers 100 and 103. Thereby, the capacitor electrode layer 100 is opposed to the coil electrode layers 30 and 42 with the

dielectric layers

16c and 18 interposed therebetween, thereby forming capacitors C9 and C12. Further, the capacitor electrode layer 103 is opposed to the coil electrode layers 34 and 38 with the

dielectric layers

22 and 24c interposed therebetween, thereby forming capacitors C10 and C11.

Furthermore, the capacitor electrode layer 100 has lead

portions

101 and 102 at both ends in the x-axis direction. The

lead portions

101 and 102 are connected to the external electrodes E9 and E10, respectively. As a result, the capacitor C9 is connected between the coil L1 and the external electrodes E9 and E10 as shown in FIG. Similarly, the capacitor C12 is connected between the coil L4 and the external electrodes E9 and E10 as shown in FIG.

The capacitor electrode layer 103 has lead

portions

104 and 105 at both ends in the x-axis direction. The

lead portions

104 and 105 are connected to the external electrodes E9 and E10, respectively. As a result, the capacitor C10 is connected between the coil L2 and the external electrodes E9 and E10 as shown in FIG. Similarly, the capacitor C11 is connected between the coil L3 and the external electrodes E9 and E10 as shown in FIG.

According to the noise filter 10c, common mode noise can be efficiently removed as described below. More specifically, when the magnetic flux generated by the coil penetrates the electrode layer, eddy current loss occurs in the electrode layer, and the common mode noise removal characteristics of the noise filter are degraded. Therefore, in the noise filter 10c, the capacitor electrode layers 100 and 103 are provided with blank portions. As a result, the magnetic flux generated in the coils L1 to L4 penetrates through the blank portions of the capacitor electrode layers 100 and 103, and no eddy current loss occurs in the capacitor electrode layers 100 and 103, and the coils L1 to L4. The magnetic flux generated at becomes stronger. As a result, the temporal coupling of the coils L1 to L4 is strengthened, and the common mode noise removal characteristics are improved in the noise filter 10c. Further, since the magnetic flux generated in the coils L1 to L4 becomes stronger, the normal mode noise removal characteristics by the LC filters LC1 to LC4 are also improved.

In the noise filter 10c, the coil electrode layers 30, 34, 38, and 42 serve as both the coil electrode layer and the capacitor electrode layer. Therefore, in the noise filter 10c, the number of dielectric layers can be reduced compared to the noise filter 10a.

(Fourth embodiment)
The configuration of the noise filter 10d according to the fourth embodiment will be described below with reference to the drawings. FIG. 12 is an exploded perspective view of the multilayer body 12d of the noise filter 10d according to the fourth embodiment. FIG. 13 is an equivalent circuit diagram of the noise filter 10d. 12 and 13, the same reference numerals are assigned to the same components as those in FIGS. 2, 3, 10, and 11.

As shown in FIG. 12, the laminated body 12d is different from the laminated body 12c shown in FIG. 10 in that

dielectric layers

16a, 16b, 24a, and 24b are further added. The

dielectric layers

16a, 16b, 24a, and 24b are the same as those included in the stacked body 12a shown in FIG.

According to the laminated body 12d as described above, as shown in FIG. 13, the capacitor C1 is provided between the external electrode E2 and the external electrodes E9 and E10, and between the external electrode E4 and the external electrodes E9 and E10. The capacitor C2 is provided, the capacitor C3 is provided between the external electrode E6 and the external electrodes E9 and E10, and the capacitor C4 is provided between the external electrode E8 and the external electrodes E9 and E10. Thereby, the noise filter 10d can have a steep and large filter insertion loss with respect to normal mode noise and common mode noise by adopting a saddle type structure.

(Fifth embodiment)
The configuration of the noise filter 10e according to the fifth embodiment will be described below with reference to the drawings. FIG. 14 is an exploded perspective view of the multilayer body 12e of the noise filter 10e according to the fifth embodiment. 14, the same components as those in FIG. 2 are given the same reference numerals.

As shown in FIG. 14, the laminated body 12e is provided with

dielectric layers

16d, 16e, 24d, and 24e instead of the

dielectric layers

16a, 16b, 24a, and 24b. Is different. Below, the difference between the laminated body 12e and the laminated body 12a is demonstrated.

Capacitor electrode layers 150, 152, 154, and 156 are formed on the dielectric layer 16d. The capacitor electrode layers 150, 152, 154, and 156 are formed to have a narrower width in the x-axis direction than the capacitor electrode layers 50, 52, 54, and 56 shown in FIG. Accordingly, the capacitor electrode layers 150, 152, 154, and 156 (signal electrodes) do not overlap with the coil axes of the coils L1 and L4 when viewed in plan from the z-axis direction. Furthermore, lead

portions

151, 153, 155, and 157 connected to the external electrodes E 2, E 4, E 6, and E 8 are respectively provided at the negative end portions in the y-axis direction of the capacitor electrode layers 150, 152, 154, and 156. Is provided.

Further, a capacitor electrode layer 158 is formed on the dielectric layer 16e. The capacitor electrode layer 158 has an electrode layer formed so as to overlap with the capacitor electrode layers 150, 152, 154, 156 and not to overlap with the coil axes of the coils L1, L4 when viewed in plan from the z-axis direction. It is formed to have no blanks.

Further, capacitor electrode layers 160, 162, 164 and 166 are formed on the dielectric layer 24d. The capacitor electrode layers 160, 162, 164, and 166 are formed to have a narrower width in the x-axis direction than the capacitor electrode layers 60, 62, 64, and 66 shown in FIG. Thereby, the capacitor electrode layers 160, 162, 164, and 166 do not overlap with the coil axes of the coils L2 and L3 when viewed in plan from the stacking direction. Furthermore, lead

portions

161, 163, 165, and 167 connected to the external electrodes E 2, E 4, E 6, and E 8 are respectively provided at end portions on the negative side in the y-axis direction of the capacitor electrode layers 160, 162, 164, and 166. Is provided.

Further, a capacitor electrode layer 168 is formed on the dielectric layer 24e. The capacitor electrode layer 168 has an electrode layer formed so as to overlap with the capacitor electrode layers 160, 162, 164, 166 and not to overlap with the coil axes of the coils L2, L3 when viewed in plan from the z-axis direction. It is formed to have no blanks.

The noise filter 10e having the above configuration has the circuit configuration shown in FIG. 2 in the same manner as the noise filter 10a.

According to the noise filter 10e, the capacitor electrode layers 150, 152, 154, 156, 158, 160, 162, 164, 166, and 168 do not overlap the coils L1 to L4 when viewed in plan from the z-axis direction. Is formed. Therefore, in the noise filter 10e, the occurrence of eddy current loss in the capacitor electrode layers 150, 152, 154, 156, 158, 160, 162, 164, 166, and 168 is suppressed, and the magnetic flux generated in the coils L1 to L4 is strong. Become. As a result, the magnetic coupling between the coil L1 and the coil L2 and the magnetic coupling between the coil L3 and the coil L4 are strengthened, and the common mode noise removal characteristics of the noise filter 10e are improved as compared with the noise filter 10a.

(Sixth embodiment)
The configuration of the noise filter 10f according to the sixth embodiment will be described below with reference to the drawings. FIG. 15 is an exploded perspective view of the multilayer body 12f of the noise filter 10f according to the sixth embodiment. 15, the same components as those in FIGS. 2 and 14 are denoted by the same reference numerals.

As shown in FIG. 15, the laminated body 12f is provided with

dielectric layers

16d, 16e, 16f, 24d, 24e, and 24f instead of the

dielectric layers

16a, 16b, 24a, and 24b. It differs from the laminate 12b shown in FIG. Below, the difference between the laminated body 12f and the laminated body 12b will be described.

As shown in FIG. 15, the laminated body 12f is provided with a dielectric layer 16f between a dielectric layer 14c and a dielectric layer 16d. Capacitor electrode layers 250, 252, 254, and 256 are formed on the dielectric layer 16f. The capacitor electrode layers 250, 252, 254, and 256 are formed so as to overlap with the capacitor electrode layer 158 when viewed in plan from the z-axis direction. Thereby, the capacitor electrode layer 250 and the capacitor electrode layer 150 form a capacitor C5. Capacitor electrode layer 252 and capacitor electrode layer 152 constitute capacitor C6. Capacitor electrode layer 254 and capacitor electrode layer 154 constitute capacitor C7. Capacitor electrode layer 256 and capacitor electrode layer 156 form capacitor C8. Furthermore, lead

portions

251, 253, 255, and 257 connected to the external electrodes E 1, E 3, E 5, and E 7 are respectively provided at the positive end portions in the y-axis direction of the capacitor electrode layers 250, 252, 254, and 256. Is provided.

Further, capacitor electrode layers 260, 262, 264, and 266 are formed on the dielectric layer 24f. The capacitor electrode layers 260, 262, 264, and 266 are formed so as to overlap the capacitor electrode layer 168 when viewed in plan from the z-axis direction. Thereby, the capacitor electrode layer 260 and the capacitor electrode layer 160 constitute a capacitor C5. The capacitor electrode layer 262 and the capacitor electrode layer 162 constitute a capacitor C6. Capacitor electrode layer 264 and capacitor electrode layer 164 constitute capacitor C7. Capacitor electrode layer 266 and capacitor electrode layer 166 constitute capacitor C8. Furthermore, lead

portions

261, 263, 265, 267 connected to the external electrodes E 1, E 3, E 5, E 7 are respectively provided at the ends on the positive side in the y-axis direction of the capacitor electrode layers 260, 262, 264, 266. Is provided.

The noise filter 10f having the above configuration has the circuit configuration shown in FIG. 9 in the same manner as the noise filter 10b.

According to the noise filter 10f, the capacitor electrode layers 158, 168, 250, 252, 254, 256, 260, 262, 264, and 266 do not overlap with the coils L1 to L4 when viewed in plan from the z-axis direction. Is formed. Therefore, in the noise filter 10f, the occurrence of eddy current loss in the capacitor electrode layers 158, 168, 250, 252, 254, 256, 260, 262, 264, and 266 is suppressed, and the magnetic flux generated in the coils L1 to L4 is strong. Become. As a result, the magnetic coupling between the coil L1 and the coil L2 and the magnetic coupling between the coil L3 and the coil L4 are strengthened, and the common mode noise removal characteristics of the noise filter 10f are improved as compared with the noise filter 10b.

(Seventh embodiment)
The configuration of the noise filter 10g according to the seventh embodiment will be described below with reference to the drawings. FIG. 16 is an exploded perspective view of the multilayer body 12g of the noise filter 10g according to the seventh embodiment. 16, the same components as those in FIGS. 2 and 14 are denoted by the same reference numerals.

As shown in FIG. 16, the laminated body 12g is provided with

dielectric layers

16d, 16e, 24d, and 24e instead of the

dielectric layers

16a, 16b, 24a, and 24b. It is different from 12d. The

dielectric layers

16d, 16e, 24d, and 24e are the same as those shown in FIG.

The noise filter 10g having the above configuration has the circuit configuration shown in FIG. 13 in the same manner as the noise filter 10d.

According to the noise filter 10g, the capacitor electrode layers 150, 152, 154, 156, 158, 160, 162, 164, 166, and 168 do not overlap with the coils L1 to L4 when viewed in plan from the z-axis direction. Is formed. Therefore, in the noise filter 10g, the generation of eddy current loss in the capacitor electrode layers 150, 152, 154, 156, 158, 160, 162, 164, 166, and 168 is suppressed, and the magnetic flux generated in the coils L1 to L4 is strong. Become. As a result, the magnetic coupling between the coil L1 and the coil L2 and the magnetic coupling between the coil L3 and the coil L4 become stronger, and the common mode noise removal characteristics of the noise filter 10g are improved as compared with the noise filter 10d.

(Eighth embodiment)
The configuration of the noise filter 10h according to the eighth embodiment will be described below with reference to the drawings. FIG. 17 is an exploded perspective view of the multilayer body 12h of the noise filter 10h according to the eighth embodiment. FIG. 18 is an equivalent circuit diagram of the noise filter 10h. 17 and 18, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals.

As shown in FIG. 17, the laminated body 12h is different from the laminated body 12a shown in FIG. 2 in that a dielectric layer 24g is provided between the dielectric layer 24a and the dielectric layer 26c. Below, the difference between the laminated body 12h and the laminated body 12a will be described.

In the laminated body 12h, as shown in FIG. 17, a dielectric layer 24g is provided between the dielectric layer 24a and the dielectric layer 26c. Capacitor electrode layers 360, 362, 364, and 366 are formed on the dielectric layer 24g. The capacitor electrode layers 360, 362, 364, and 366 are formed so as to overlap with the capacitor electrode layers 60, 62, 64, and 66, respectively, when viewed in plan from the z-axis direction. Thereby, the capacitor electrode layer 60 and the capacitor electrode layer 360 constitute a capacitor C13. The capacitor electrode layer 62 and the capacitor electrode layer 362 constitute a capacitor C14. Capacitor electrode layer 64 and capacitor electrode layer 364 constitute capacitor C15. Capacitor electrode layer 66 and capacitor electrode layer 366 constitute capacitor C16. Further,

lead portions

361, 363, 365, and 367 connected to the external electrodes E1, E3, E5, and E7 are respectively provided at the ends on the positive side in the y-axis direction of the capacitor electrode layers 360, 362, 364, and 366. Is provided.

The noise filter 10h having the above configuration has a circuit configuration shown in FIG. More specifically, capacitors C13, C14, C15, and C16 are formed between both ends of the coils L1, L2, L3, and L4. Then, by adjusting the shape and area of the capacitor electrode layers 360, 362, 364, and 366, the capacitance of the capacitors C13, C14, C15, and C16 can be adjusted, and the common mode noise and the normal mode noise of the noise filter 10h can be removed. The characteristics can be adjusted.

Note that the dielectric layer 24g may also be provided for the noise filters 10b to 10g.

The noise filters 10a to 10h may include one or more common mode choke coils.

(Ninth embodiment)
FIG. 19 is an external perspective view of noise filters 410a to 410n according to the ninth embodiment. FIG. 20 is an exploded view of the multilayer body 412a of the noise filter 410a. FIG. 21 is an equivalent circuit diagram of the noise filter 410a. Hereinafter, when the noise filter 410a is formed, the direction in which the ceramic green sheets are stacked is defined as the stacking direction. This stacking direction is the z-axis direction, the longitudinal direction of the noise filter 410a is the x-axis direction, and the direction orthogonal to the x-axis and the z-axis is the y-axis direction. The x-axis, y-axis, and z-axis are parallel to the sides that constitute the noise filter 410a.

(Noise filter configuration)
As shown in FIG. 19, the noise filter 410a includes a rectangular parallelepiped laminated body 412a including a plurality of LC filters and a common mode choke coil therein, and external electrodes E11 to E20 formed on the surface of the laminated body 412a. ing. Hereinafter, surfaces positioned at both ends in the x-axis direction of the stacked body 412a are defined as end surfaces, surfaces positioned at both ends in the y-axis direction of the stacked body 412a are defined as side surfaces, and the upper side in the z-axis direction of the stacked body 412a is defined. The surface is defined as the upper surface, and the lower surface in the z-axis direction of the stacked body 412a is defined as the lower surface.

External electrodes E11, E13, E15, and E17 are each formed to extend in the z-axis direction on the side surface on the positive direction side in the y-axis direction. Each of the external electrodes E11, E13, E15, E17 functions as an input terminal. The external electrodes E12, E14, E16, and E18 are each formed to extend in the z-axis direction on the side surface on the negative direction side in the y-axis direction. The external electrodes E12, E14, E16, E18 each function as an output terminal. The external electrodes E19 and E20 are each formed to extend in the z-axis direction on both end faces. The external electrodes E19 and E20 each function as a ground electrode.

As will be described below, the multilayer body 412a is formed by laminating a plurality of internal electrode layers and a plurality of dielectric layers, and includes LC filters LC11 to LC14 and common mode choke coils L31 and L32 therein. ing. More specifically, as shown in FIG. 20, the stacked body 412a includes a plurality of dielectric layers 414a to 414c, 416a, 416b, 418a to 418f, 420, 422a to 422f, 424a, 424b, 426a to 426c in this order. It is configured by being laminated. The plurality of dielectric layers 414a to 414c, 416a, 416b, 418a to 418f, 420, 422a to 422f, 424a, 424b, and 426a to 426c are rectangular insulating layers each having substantially the same area and shape.

On the main surface of the dielectric layer 416a, rectangular capacitor electrode layers 450, 452, 454 and 456 having a longitudinal direction in the y-axis direction are formed. Capacitor electrode layers 450, 452, 454, and 456 connect capacitor electrode layers 450, 452, 454, and 456 to external electrodes E12, E14, E16, and E18, respectively, at the end on the negative side in the y-axis direction. The

drawer portions

451, 453, 455, and 457 are provided. A rectangular capacitor electrode layer 458 having a longitudinal direction in the x-axis direction is formed on the main surface of the dielectric layer 416b. The capacitor electrode layer 458 has lead

portions

471 and 472 for connecting the capacitor electrode layer 458 and the external electrodes E19 and E20 at both ends in the x-axis direction.

The capacitor electrode layer 450 and the capacitor electrode layer 458 are opposed to each other with the dielectric layer 416a interposed therebetween, thereby forming the capacitor C21. The capacitor electrode layer 452 and the capacitor electrode layer 458 are opposed to each other with the dielectric layer 416a interposed therebetween, thereby forming the capacitor C22. The capacitor electrode layer 454 and the capacitor electrode layer 458 are opposed to each other with the dielectric layer 416a interposed therebetween, thereby forming the capacitor C23. The capacitor electrode layer 456 and the capacitor electrode layer 458 are opposed to each other with the dielectric layer 416a interposed therebetween, thereby forming the capacitor C24.

Coil electrode layers 430a to 430f and 442a to 442f having shapes in which linear electrodes are bent are formed on the principal surfaces of the dielectric layers 418a to 418f, respectively. More specifically, each of the coil electrode layers 430a and 442a has an “L” shape, and one end thereof is connected to the external electrodes E12 and E18. The coil electrode layers 430b to 430e and 442b to 442e are electrode layers formed on the same dielectric layer 418 and formed in a spiral shape so as to rotate in opposite directions. The coil electrode layers 430f and 442f each have an “L” shape, and one ends thereof are connected to the external electrodes E11 and E17, respectively. Furthermore, via conductors 432a to 432e and 444a to 444e connected to one ends of the coil electrode layers 430a to 430e and 442a to 442e are formed in the dielectric layers 418a to 418e, respectively. As a result, when the dielectric layers 418a to 418f are stacked, the via conductors 432a to 432e and 444a to 444e are coil electrode layers 430a to 430f and 442a to 442f formed on the adjacent dielectric layers 418a to 418f. Connect each other. As a result, the coil electrode layers 430a to 430f constitute the coil L21, and the coil electrode layers 442a to 442f constitute the coil L24.

On the main surface of the dielectric layer 424a, rectangular capacitor electrode layers 460, 462, 464, and 466 having a longitudinal direction in the y-axis direction are formed. Capacitor electrode layers 460, 462, 464, and 466 connect capacitor electrode layers 460, 462, 464, and 466 and external electrodes E12, E14, E16, and E18, respectively, at the negative end portion in the y-axis direction. The

drawer portions

461, 463, 465, and 467 are provided. A rectangular capacitor electrode layer 468 having a longitudinal direction in the x-axis direction is formed on the main surface of the dielectric layer 424b. The capacitor electrode layer 468 has lead

portions

473 and 474 for connecting the capacitor electrode layer 468 and the external electrodes E19 and E20 at both ends in the x-axis direction.

The capacitor electrode layer 460 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming the capacitor C21. The capacitor electrode layer 462 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming the capacitor C22. The capacitor electrode layer 464 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming the capacitor C23. The capacitor electrode layer 466 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming the capacitor C24.

Coil electrode layers 434a to 434f and 438a to 438f having shapes in which linear electrodes are bent are formed on the principal surfaces of the dielectric layers 422a to 422f, respectively. More specifically, the coil electrode layers 434a and 438a each have an “L” shape, and one ends thereof are connected to the external electrodes E14 and E16, respectively. The coil electrode layers 434b to 434e and 438b to 438e are electrode layers formed on the same dielectric layer 422 and formed in a spiral shape so as to rotate in directions opposite to each other. The coil electrode layers 434f and 438f each have an “L” shape, and one ends thereof are connected to the external electrodes E13 and E15, respectively. Furthermore, via conductors 436b to 436f and 440b to 440f connected to one ends of the coil electrode layers 434b to 434f and 438b to 438f are formed in the dielectric layers 422b to 422f, respectively. Thus, when the dielectric layers 422a to 422f are stacked, the via conductors 436b to 436f and 440b to 440f are coil electrode layers 434a to 434f and 438a to 438f formed on the adjacent dielectric layers 422a to 422f. Connect each other. As a result, the coil electrode layers 434a to 434f constitute the coil L22, and the coil electrode layers 438a to 438f constitute the coil L23.

Since the laminate 412a has the above-described configuration, as shown in FIG. 21, the LC filter LC11 including the coil L21 and the capacitor C21, the LC filter LC12 including the coil L22 and the capacitor C22, the coil L23, and the capacitor C23 are included. The LC filter LC13 including the LC filter LC13 and the coil L24 and the capacitor C24 is formed. The LC filters LC12 and LC13 are not electrically connected to the LC filters LC11 and LC14. Here, taking the LC filter LC11 as an example, one end of the coil L21 is connected to the external electrode E11, and the other end of the coil L21 is connected to the external electrode E12. Furthermore, one end of the capacitor C21 is connected to the other end of the coil L21, and the other end of the capacitor C21 is connected to the external electrodes E19 and E20. Since the configurations of the LC filters LC12, LC13, and LC14 are the same as the configuration of the LC filter LC11, the description thereof is omitted.

Incidentally, since the external electrodes E11 and E13 function as input terminals and the external electrodes E12 and E14 function as output terminals, in FIG. 20, for example, a current flows through the coil L21 from the bottom to the top in the z-axis direction. In the coil L22, for example, a current flows from the top to the bottom in the z-axis direction. That is, current flows through the coil L21 and the coil L22 in the reverse direction in the z-axis direction. Further, the coil electrode layers 430a to 430f constituting the coil L21 rotate clockwise as it goes from the bottom to the top in the z-axis direction, and the coil electrode layers 434a to 434f constituting the coil L22 are rotated in the z-axis direction. It turns counterclockwise as it goes from bottom to top. That is, the coil L21 and the coil L22 are rotated in opposite directions. Therefore, when current flows through the coil L21 and the coil L22, the current rotates in the same direction. Furthermore, as shown in FIG. 20, the coil L21 and the coil L22 are arranged side by side in the z-axis direction so that the coil axis of the coil L21 and the coil axis of the coil L22 substantially coincide. As a result, the coil L21 and the coil L22 generate magnetic fluxes in the same direction and are magnetically coupled, so that the coils constituting the LC filter LC11 and the LC filter LC12 and the two constituting the common mode choke coil L31 are combined. It comes to share with the coil. In particular, the coil L21 and the coil L22 are magnetically coupled in the vicinity of the other end (the central portion in the z-axis direction in FIG. 20) with respect to the end to which the capacitors C21 and C22 are connected. The coupling coefficient between the coil L21 and the coil L22 is 0.3 or more and 0.7 or less. The coil L23 and the coil L24 are also magnetically coupled to serve as both the coil constituting the LC filter LC13 and the LC filter LC14 and the two coils constituting the common mode choke coil L32. For details, see the coil L21. Since this is the same as the coil L22, the description thereof is omitted.

The coupling coefficient between the coil L21 and the coil L22 is measured according to the following procedure. In measuring the coupling coefficient between the coil L21 and the coil L22, first, the external electrode E11 and the external electrode E13 in FIG. 21 are short-circuited, and the inductance value Ldd between the external electrodes E12 and E14 is measured. Next, the external electrode E11 and the external electrode E13 are short-circuited, the external electrode E12 and the external electrode E14 are short-circuited, and the inductance value Lcc between the external electrodes E11 and E13 and the external electrodes E12 and E14 is measured. Then, the inductance values Ldd and Lcc are substituted into the following formula (1) to obtain the coupling coefficient K.

K = (2Lcc-Ldd / 2) / (2Lcc + Ldd / 2) (1)

Since the measurement of the coupling coefficient between the coil L23 and the coil L24 is the same as the measurement of the coupling coefficient between the coil L21 and the coil L22, description thereof is omitted.

Furthermore, a coupling electrode layer 470 for capacitively coupling the coil L21 and the coils L23 and L24 is formed on the main surface of the dielectric layer 420 disposed between the dielectric layer 418f and the dielectric layer 422f. Yes. The coupling electrode layer 470 is capacitively coupled to the coil L22 and the coils L23 and L24. Similarly, the coupling electrode layer 470 is capacitively coupled to the coils L21 and L22 for the coils L23 and L24. Therefore, the coupling electrode layer 470 is formed between the LC filter LC11 and the LC filters LC13 and LC14 when viewed in plan from the z-axis direction. Similarly, the coupling electrode layer 470 is formed across the LC filter LC12 and the LC filters LC13 and LC14 when viewed in plan from the z-axis direction.

Here, the coupling electrode layer 470 has a shape in which two annular linear electrodes are connected. This is to prevent the coupling electrode layer 470 from preventing the magnetic flux generated in the coils L21 to L24 when a current flows through the coils L21 to L24.

(effect)
As described above, according to the noise filter 410a, the LC filters LC11 to LC14 are incorporated, and the coils L21 to L24 also serve as the coils constituting the common mode choke coils L31 and L32. Both common mode noises can be removed.

In particular, in the noise filter 410a, as described below, the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are 0.3 or more and 0.7 or less. The normal mode noise generated in the differential signal transmitted between the receiver and the receiver can be effectively removed.

More specifically, the present inventor performed a computer simulation described below in order to confirm the effect produced by the noise filter 410a. 22 to 25 are graphs showing the results of computer simulation. In the noise filter 410a, the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are 0.2, 0.3. , 0.6, 0.7 is a graph showing the relationship between filter insertion loss and frequency for normal mode noise. The vertical axis represents filter insertion loss with respect to noise, and the horizontal axis represents frequency.

The frequency of the differential signal transmitted between the mobile phone driver and the receiver is about 100 MHz. In such a differential signal, the insertion loss of the filter with respect to normal mode noise in the vicinity of 300 MHz, which is the third harmonic, needs to be smaller than 3 dB. This is because if the insertion loss of the filter with respect to the normal mode noise near 300 MHz is too large, the differential signal itself is adversely affected.

Therefore, referring to the graph shown in FIG. 22, when the coupling coefficient is 0.2, it can be seen that the insertion loss of the filter with respect to the normal mode noise at 300 MHz is about 5 dB. On the other hand, referring to the graph shown in FIG. 23, when the coupling coefficient is 0.3, the insertion loss of the filter with respect to the normal mode noise at 300 MHz is about 3 dB. Therefore, the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are preferably 0.3 or more.

Also, the insertion loss of the filter with respect to normal mode noise in the vicinity of the UHF band 470 MHz, which is the lower limit frequency used in the mobile phone, needs to be larger than 10 dB. This is to prevent UHF band signal harmonics from affecting the UHF band reception performance as normal mode noise.

Therefore, referring to the graph shown in FIG. 25, when the coupling coefficient is 0.7, the insertion loss of the filter with respect to the normal mode noise at 550 MHz is about 10 dB. Referring to the graph shown in FIG. 24, when the coupling coefficient is 0.6, the insertion loss of the filter with respect to the normal mode noise at 470 MHz is about 10 dB. Therefore, the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are preferably 0.7 or less, and more preferably 0.6 or less.

As described above, since the noise filter 410a has the common mode choke coils L31 and L32, common mode noise generated between the driver and the receiver of the mobile phone can be removed. Furthermore, the noise filter 410a has a coupling coefficient between the coil L21 and the coil L22 and a coupling coefficient between the coil L23 and the coil L24 that is not less than 0.3 and not more than 0.7, thereby suppressing the deterioration of the differential signal waveform. However, normal mode noise can also be removed. Therefore, the noise filter 410a is suitable for the common mode noise countermeasure and the normal mode noise countermeasure between the driver and the receiver of the mobile phone.

Next, the inventor of the present application conducted an experiment to clarify the effect of the noise filter 410a. More specifically, a first experimental example corresponding to the noise filter 410a was produced, and a second experimental example corresponding to the multilayer array component described in Patent Document 1 was produced. The coupling coefficient of the second experimental example was set to 0.05 or less. As a first experiment, a rectangular wave was input to these experimental examples, and the output signal output was measured. As a second experiment, the intensity distribution of noise when a noise filter was inserted was measured.

FIG. 26 is a graph showing the results of performing the first experiment in the first experimental example. FIG. 27 is a graph showing the results when the first experiment was performed in the second experiment example. In FIG.26 and FIG.27, the vertical axis | shaft has shown the signal level and the horizontal axis has shown time.

FIG. 28 is a graph showing a result of performing the second experiment in the second experimental example. FIG. 29 is a graph showing the results of performing the second experiment in the first experimental example. In FIG.28 and FIG.29, the vertical axis | shaft has shown the noise level and the horizontal axis has shown the frequency.

In the first experiment, when a rectangular wave is input to the first experimental example and the second experimental example, noise at high frequencies is removed, and as shown in FIGS. In both experimental examples, a sinusoidal signal has been output. 26 and 27, it can be seen that the output signal of FIG. 26 has a waveform closer to the input signal than the output signal of FIG. Therefore, it can be understood that the degree of deterioration of the output signal when the rectangular wave is used as the input signal is smaller in the first experimental example than in the second experimental example. That is, it can be understood that the degradation of the output signal in the noise filter 410a is smaller than the degradation of the output signal in the multilayer array component described in Patent Document 1.

Furthermore, in the second experiment, noise having the same intensity distribution was input to the first experiment example and the second experiment example. As a result, as shown in FIGS. 28 and 29, it can be seen that substantially the same noise removal effect can be obtained in the first experimental example and the second experimental example. That is, it can be understood that the noise removal effect in the noise filter 410a is equivalent to the noise removal effect in the multilayer array component described in Patent Document 1.

As described above, according to the first experiment and the second experiment, it is understood that the noise filter 410a can obtain a good noise removal effect while reducing the deterioration of the waveform of the output signal.

Further, according to the noise filter 410a, the LC filter and the common mode choke coil are built in one noise filter 410a, and therefore the LC filter and the common mode choke coil are configured by separate electronic components. As a result, the entire circuit can be reduced in size. In particular, in the noise filter 410a, the coils L21 and L22 function as coils constituting the common mode choke coil L31 and also function as part of the LC filters LC11 and LC12. Similarly, the coils L23 and L24 function as coils constituting the common mode choke coil L32 and also function as part of the LC filters LC13 and LC14. As described above, in the noise filter 410a, the coils L21 to L24 are also used as a part of the LC filter and a part of the common mode choke coil, so that the noise filter 410a is further downsized.

Also, the noise filter 410a can efficiently remove common mode noise as described below. In the xz cross section, when the magnetic flux generated by the coil L21 and the magnetic flux generated by the coil L22, and the magnetic flux generated by the coil L23 and the magnetic flux generated by the coil L24 are not equal, normal mode noise is converted into common mode noise. As a result, new common mode noise is generated, and the common mode noise is not efficiently removed. Therefore, in the noise filter 410a, the current paths of the coils L21 and L22 are configured so that the magnitude of the magnetic flux generated by the coil L21 and the magnitude of the magnetic flux generated by the coil L22 are substantially equal in the xz section. Similarly, in the xz cross section, the current path is configured so that the magnitude of the magnetic flux generated by the coil L23 and the magnitude of the magnetic flux generated by the coil L24 are substantially equal. Thereby, the difference in the characteristics between the coil L21 and the coil L22 and between the coil L23 and the coil L24 can be reduced. Therefore, normal mode noise is not converted into common mode noise, and new common mode noise is not generated. Therefore, in the noise filter 410a, common mode noise can be more efficiently removed by the common mode choke coil L31 and the common mode choke coil L32.

In addition, when the capacitor electrode is not line symmetric with respect to the dielectric layer 420 in the xz cross section, the magnitude of the magnetic flux is difficult to be equal, so normal mode noise is converted into common mode noise, and a new common Mode noise occurs and common mode noise is not efficiently removed. On the other hand, as shown in FIG. 20, the capacitor electrode layers 450, 452, 458, 460, 462, and 468 have boundaries between the LC filter LC11 and the LC filter LC12 in the xz section (the dielectric layer 420 in FIG. 20). On the other hand, it has a substantially line-symmetric structure. Similarly, as shown in FIG. 20, the capacitor electrode layers 454, 456, 458, 464, 466, and 468 have boundary lines between the LC filter LC13 and the LC filter LC14 (dielectric layer 420 in FIG. 20) in the xz cross section. On the other hand, it has a substantially line-symmetric structure. Thereby, the influence which capacitor electrode layer 450,452,458 exerts on the magnetic flux by coil L21 and the influence which capacitor electrode layer 460,462,468 exerts on the magnetic flux by coil L22 can be made equal. Similarly, the influence of the capacitor electrode layers 454, 456, 458 on the magnetic flux by the coil L24 can be made equal to the influence of the capacitor electrode layers 464, 466, 468 on the magnetic flux by the coil L23. That is, the difference in characteristics between the coil L21 and the coil L22 and between the coil L23 and the coil L24 can be further reduced. Therefore, normal mode noise is not converted into common mode noise, and new common mode noise is not generated. Therefore, in the noise filter 410a, common mode noise can be more efficiently removed by the common mode choke coil L31 and the common mode choke coil L32.

In general, to increase the noise suppression effect, the insertion loss characteristic may be increased. However, in order to further increase the effect, it is important to suppress the reflection of the noise and to reduce the reflection against the noise. It becomes. In the noise filter 410a, the common mode choke coil L31 and the common mode choke coil L32 are capacitively coupled to generate noise circulation between the common mode choke coils L31 and L32, thereby reducing reflection. FIG. 30 is a graph showing the relationship between the reflection characteristic of common mode noise and the frequency. The vertical axis represents the reflection characteristics, and the horizontal axis represents the frequency. On the vertical axis in the graph, 0 db indicates total reflection.

As shown in FIG. 20, in the noise filter 410a, a coupling electrode layer 470 is provided. The coupling electrode layer 470 capacitively couples a set of coils L21 and L22 and a set of coils L23 and L24. Thereby, as shown in the graph of FIG. 30, the noise filter 410 a can suppress the reflection of the common mode noise more than the noise filter without the coupling electrode layer 470. Incidentally, when the coupling electrode layer 470 is not provided, for example, the coupling capacitance between the coil L21 and the coil L23 is about 0.5 pF, but when the coupling electrode layer 470 is provided, the coil L21 and the coil L23 are provided. And the coupling capacitance is about 5 pF. As shown in FIG. 20, all of the coils L21 to L24 may be capacitively coupled, or three or two of the coils L21 to L24 may be capacitively coupled. However, when two coils are capacitively coupled, one of the coils L21 and L22 and one of the coils L23 and L24 need to be capacitively coupled.

In the noise filter 410a, the coil electrode layers 430a to 430f, 434a to 434f, the capacitor electrode layers 450, 452, 458, 460, 462, and 468, and the dielectric layers 416a, 416b, 418a to 418f, 422a to 422f, As shown in FIG. 20, the coils 424a and 424b are stacked such that the coils L21 and L22 are positioned between the capacitors C21 and C22 in the z-axis direction. That is, no capacitor is provided between the coil L21 and the coil L22. Therefore, the magnetic flux generated in the coil L21 and the coil L22 is not easily disturbed by the capacitors C21 and C22. Thereby, the magnetic flux in the coils L21 and L22 can be increased, the normal mode noise removal characteristics of the LC filters LC11 and LC12 can be improved, and the magnetic coupling between the LC filter LC11 and the LC filter LC12 is increased. Therefore, the common mode noise removal characteristics of the common mode choke coil L31 can be improved. The same applies to the LC filters LC13 and LC14 and the coils L23 and L24.

Incidentally, in the noise filter 410a, as shown in FIG. 21, stray capacitances CP11 and CP12 are generated. The stray capacitance CP11 is generated between the coil L21 and the coil L22 and between the coil L23 and the coil L24 by overlapping the coil electrode layer 430, the coil electrode layer 434, the coil electrode 438, and the coil electrode 442 in the z-axis direction. Stray capacitance. Since the stray capacitance CP11 is generated, the normal mode noise of the noise filter 410a can be efficiently removed and the change in the insertion loss of the filter with respect to the normal mode noise is steep as described below with reference to FIG. Can be.

Further, the stray capacitance CP12 is a stray capacitance generated at both ends of the coils L21 to L24 by overlapping the coil electrode layers 430, 434, 438, and 442 in the z-axis direction. Since the stray capacitance CP12 is generated, the cutoff frequency of the normal mode noise and common mode noise can be lowered and the filter for the normal mode noise and common mode noise can be reduced as described below with reference to FIG. The change in insertion loss can be made steep. 31 and 32 are graphs showing the relationship between the insertion loss of the filter and the frequency with respect to normal mode noise and common mode noise. The vertical axis represents insertion loss, and the horizontal axis represents frequency.

First, the effect produced by the stray capacitance CP11 will be described. FIG. 31 shows the insertion loss of the filter for normal mode noise when it is assumed that there is a stray capacitance CP11, and the insertion loss of the filter for normal mode noise when it is assumed that there is no stray capacitance CP11. Since the common mode noise is not affected by the stray capacitance CP11, the common mode insertion loss is not shown in FIG.

As shown in FIG. 21, when the stray capacitance CP11 is generated, the coils L21 and L22 and the stray capacitance CP11 constitute an LC filter. Therefore, when the stray capacitance CP11 is generated, the normal mode noise at the resonance point on the high frequency side can be efficiently removed as shown in FIG. 31 compared to the case where the stray capacitance CP11 is not generated. Further, when the stray capacitance CP11 is generated, the insertion loss of the filter with respect to the normal mode noise at the resonance point on the high frequency side changes abruptly as shown in FIG. 31 as compared with the case where the stray capacitance CP11 is not generated.

Next, the effect produced by the stray capacitance CP12 will be described. FIG. 32 shows filter insertion loss for normal mode noise and common mode noise when it is assumed that there is a stray capacitance CP12, and filter insertion for normal mode noise and common mode noise when there is no stray capacitance CP12. Loss is shown.

When the stray capacitance CP12 is generated, as compared with the case where the stray capacitance CP12 is not generated, the frequencies of the resonance points of normal mode noise and common mode noise are lower as shown in FIG. That is, when the stray capacitance CP12 is generated, the cut-off frequency becomes lower than when the stray capacitance CP12 is not generated. Furthermore, when the stray capacitance CP12 is generated, the normal mode noise and the common mode insertion loss at the resonance point on the high frequency side are sharply changed as shown in FIG. 32, compared to the case where the stray capacitance CP12 is not generated.

(Modification)
In the noise filter 410a shown in FIG. 20, the coupling electrode layer 470 has a shape in which two annular linear electrodes are connected, but the shape of the coupling electrode layer 470 is not limited thereto. The coupling electrode layer 470 only needs to have a shape that does not hinder the magnetic flux generated in the coils L21 to L24. That is, the coupling electrode layer 470 may be formed so as not to overlap with the coils L21 to L24 when viewed in plan from the z-axis direction. Therefore, the coupling electrode layer 470 may have a shape as a modification of the coupling electrode layer 470 shown in FIGS. 33 (a) to 33 (g). The coupling electrode layer 470 may be a solid pattern electrode as shown in FIG. The coupling electrode layer 470 shown in FIG. 33 (g) is not grounded and therefore does not affect the magnetic coupling.

(Tenth embodiment)
The configuration of the noise filter 410b according to the tenth embodiment will be described below with reference to the drawings. FIG. 34 is an exploded perspective view of the multilayer body 412b of the noise filter 410b according to the tenth embodiment. FIG. 35 is an equivalent circuit diagram of the noise filter 410b. 34 and 35, the same components as those in FIGS. 20 and 21 are denoted by the same reference numerals.

As shown in FIG. 34, the multilayer body 412b has a structure in which capacitor electrode layers 480, 482, 484, 486, 490, 492, 494, and 496 are formed on the dielectric layers 416a and 424a, respectively. And different. Hereinafter, the difference between the stacked body 412b and the stacked body 412a will be mainly described.

Capacitor electrode layers 450, 452, 454, 456, 480, 482, 484, and 486 are formed on the dielectric layer 416a. The capacitor electrode layer 480 and the capacitor electrode layer 458 constitute a capacitor C25 by facing each other with the dielectric layer 416a interposed therebetween. The capacitor electrode layer 482 and the capacitor electrode layer 458 constitute a capacitor C26 by facing each other with the dielectric layer 416a interposed therebetween. The capacitor electrode layer 484 and the capacitor electrode layer 458 constitute a capacitor C27 by facing each other with the dielectric layer 416a interposed therebetween. The capacitor electrode layer 486 and the capacitor electrode layer 458 constitute a capacitor C28 by facing each other with the dielectric layer 416a interposed therebetween.

Furthermore, a lead-out portion 481 is provided at the end of the capacitor electrode layer 480 on the positive side in the y-axis direction. Thereby, as shown in FIG. 35, the capacitor C25 is connected between the external electrode E11 and the external electrodes E19 and E20. In addition, a lead portion 483 is provided at the end of the capacitor electrode layer 482 on the positive side in the y-axis direction. As a result, as shown in FIG. 35, the capacitor C26 is connected between the external electrode E13 and the external electrodes E19, E20. In addition, a lead portion 485 is provided at the end of the capacitor electrode layer 484 on the positive side in the y-axis direction. Thereby, as shown in FIG. 35, the capacitor C27 is connected between the external electrode E15 and the external electrodes E19 and E20. A lead-out portion 487 is provided at the end of the capacitor electrode layer 486 on the positive side in the y-axis direction. Thereby, as shown in FIG. 35, the capacitor C28 is connected between the external electrode E17 and the external electrodes E19 and E20.

Capacitor electrode layers 460, 462, 464, 466, 490, 492, 494, 496 are formed on the dielectric layer 424a. The capacitor electrode layer 490 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming a capacitor C25. The capacitor electrode layer 492 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming a capacitor C26. The capacitor electrode layer 494 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming a capacitor C27. The capacitor electrode layer 496 and the capacitor electrode layer 468 are opposed to each other with the dielectric layer 424b interposed therebetween, thereby forming a capacitor C28.

Furthermore, a lead portion 491 is provided at the end of the capacitor electrode layer 490 on the positive side in the y-axis direction. Thereby, as shown in FIG. 35, the capacitor C25 is connected between the external electrode E11 and the external electrodes E19 and E20. In addition, a lead portion 493 is provided at the end of the capacitor electrode layer 492 on the positive side in the y-axis direction. As a result, as shown in FIG. 35, the capacitor C26 is connected between the external electrode E13 and the external electrodes E19, E20. A lead-out portion 495 is provided at the end of the capacitor electrode layer 494 on the positive side in the y-axis direction. Thereby, as shown in FIG. 35, the capacitor C27 is connected between the external electrode E15 and the external electrodes E19 and E20. In addition, a lead portion 497 is provided at the end of the capacitor electrode layer 496 on the positive side in the y-axis direction. Thereby, as shown in FIG. 35, the capacitor C28 is connected between the external electrode E17 and the external electrodes E19 and E20.

The noise filter 410b is added with capacitors C25 to C28 and has a saddle type structure, whereby the insertion loss of the filter with respect to normal mode noise and common mode noise can be increased sharply.

(Eleventh embodiment)
The configuration of the noise filter 410c according to the eleventh embodiment will be described below with reference to the drawings. FIG. 36 is an exploded perspective view of the multilayer body 412c of the noise filter 410c according to the eleventh embodiment. FIG. 37 is an equivalent circuit diagram of the noise filter 410c. 36 and 37, the same components as those in FIGS. 20 and 21 are denoted by the same reference numerals.

As shown in FIG. 36, the laminate 412c is different from the laminate 412a shown in FIG. 20 in that dielectric layers 416c and 424c are provided instead of the

dielectric layers

416a, 416b, 424a, and 424b. . Hereinafter, the difference between the stacked body 412c and the stacked body 412a will be mainly described.

In the noise filter 410c, as shown in FIG. 36, dielectric layers 416c and 424c on which capacitor electrode layers 500 and 503 are formed are inserted in the middle of the coils L21, L22, L23, and L24. More specifically, the dielectric layer 416c is disposed between the dielectric layer 418c and the dielectric layer 418d. The dielectric layer 424c is disposed between the dielectric layer 422c and the dielectric layer 422d. Capacitor electrode layers 500 and 503 (grounding electrodes) have blank portions in which no electrode layers are formed so as not to overlap with the coil axes of coils L21 to L24 when viewed in plan from the z-axis direction. . The via

conductors

432c, 436d, 440d, and 444c penetrate the blank portion so as not to contact the capacitor electrode layers 500 and 503. Thereby, the capacitor electrode layer 500 forms capacitors C29 and C32 so as to face the coil electrode layers 430 and 442 with the

dielectric layers

416c and 418 interposed therebetween. Further, the capacitor electrode layer 503 is opposed to the coil electrode layers 434 and 438 with the dielectric layers 422 and 424c interposed therebetween to form capacitors C30 and C31.

Furthermore, the capacitor electrode layer 500 has lead

portions

501 and 502 at both ends in the x-axis direction. The

lead portions

501 and 502 are connected to the external electrodes E19 and E20, respectively. As a result, the capacitor C29 is connected between the coil L21 and the external electrodes E19 and E20 as shown in FIG. Similarly, the capacitor C32 is connected between the coil L24 and the external electrodes E19 and E20 as shown in FIG.

The capacitor electrode layer 503 has lead

portions

504 and 505 at both ends in the x-axis direction. The

lead portions

504 and 505 are connected to the external electrodes E19 and E20, respectively. As a result, the capacitor C30 is connected between the coil L22 and the external electrodes E19 and E20 as shown in FIG. Similarly, the capacitor C31 is connected between the coil L23 and the external electrodes E19 and E20 as shown in FIG.

According to the noise filter 410c, common mode noise can be efficiently removed as described below. More specifically, when the magnetic flux generated by the coil penetrates the electrode layer, eddy current loss occurs in the electrode layer, and the common mode noise removal characteristics of the noise filter are degraded. Therefore, in the noise filter 410c, the capacitor electrode layers 500 and 503 are provided with blank portions. As a result, the magnetic flux generated in the coils L21 to L24 penetrates through the blank portions of the capacitor electrode layers 500 and 503, and no eddy current loss occurs in the capacitor electrode layers 500 and 503, and the coils L21 to L24. The magnetic flux generated at becomes stronger. As a result, the magnetic coupling of the coils L21 to L24 is strengthened, and the common mode noise removal characteristic is improved in the noise filter 410c. Further, since the magnetic flux generated in the coils L21 to L24 becomes stronger, the normal mode noise removal characteristics by the LC filters LC11 to LC14 are also improved.

Further, in the noise filter 410c, the coil electrode layers 430, 434, 438, and 442 serve as one of the coil electrode layer and the capacitor electrode layer. Therefore, in the noise filter 410c, the number of dielectric layers can be reduced as compared with the noise filter 410a.

(Twelfth embodiment)
The configuration of the noise filter 410d according to the twelfth embodiment will be described below with reference to the drawings. FIG. 38 is an exploded perspective view of the multilayer body 412d of the noise filter 410d according to the twelfth embodiment. FIG. 39 is an equivalent circuit diagram of the noise filter 410d. 38 and 39, the same components as those in FIGS. 20, 21, 36, and 37 are denoted by the same reference numerals.

The laminated body 412d is different from the laminated body 412c shown in FIG. 36 in that

dielectric layers

416a, 416b, 424a, and 424b are further added as shown in FIG. The

dielectric layers

416a, 416b, 424a, 424b are the same as those included in the stacked body 412a shown in FIG.

According to the laminated body 412d as described above, as shown in FIG. 39, the capacitor C21 is provided between the external electrode E12 and the external electrodes E19, E20, and between the external electrode E14 and the external electrodes E19, E20. The capacitor C22 is provided, the capacitor C23 is provided between the external electrode E16 and the external electrodes E19 and E20, and the capacitor C24 is provided between the external electrode E18 and the external electrodes E19 and E20. Thereby, the noise filter 410d can have a steep and large filter insertion loss with respect to normal mode noise and common mode noise by adopting a saddle type structure.

(13th Embodiment)
The configuration of the noise filter 410e according to the thirteenth embodiment will be described below with reference to the drawings. FIG. 40 is an exploded perspective view of the multilayer body 412e of the noise filter 410e according to the thirteenth embodiment. In FIG. 40, the same components as those in FIG. 20 are denoted by the same reference numerals.

As shown in FIG. 40, the stacked body 412e is provided with

dielectric layers

416d, 416e, 424d, and 424e instead of the

dielectric layers

416a, 416b, 424a, and 424b. And different. Hereinafter, differences between the stacked body 412e and the stacked body 412a will be described.

Capacitor electrode layers 550, 552, 554, and 556 are formed on the dielectric layer 416d. The capacitor electrode layers 550, 552, 554, and 556 are formed to have a narrower width in the x-axis direction than the capacitor electrode layers 450, 452, 454, and 456 shown in FIG. As a result, the capacitor electrode layers 550, 552, 554, and 556 (signal electrodes) do not overlap the coil axes of the coils L21 and L24 when viewed in plan from the z-axis direction. Further,

lead portions

551, 553, 555, and 557 connected to the external electrodes E12, E14, E16, and E18, respectively, are provided at the negative end portions of the capacitor electrode layers 550, 552, 554, and 556 in the y-axis direction. Is provided.

Further, a capacitor electrode layer 558 is formed on the dielectric layer 416e. The capacitor electrode layer 558 is formed with an electrode layer so as to overlap with the capacitor electrode layers 550, 552, 554, and 556 and not to overlap with the coil axes of the coils L21 and L24 when viewed in plan from the z-axis direction. It is formed to have no blanks.

Further, capacitor electrode layers 560, 562, 564, 566 are formed on the dielectric layer 424d. The capacitor electrode layers 560, 562, 564, and 566 are formed to have a narrower width in the x-axis direction than the capacitor electrode layers 460, 462, 464, and 466 shown in FIG. As a result, the capacitor electrode layers 560, 562, 564, 566 do not overlap with the coil axes of the coils L22, L23 when viewed in plan from the stacking direction. Further,

lead portions

561, 563, 565, and 567 connected to the external electrodes E12, E14, E16, and E18 are respectively provided at the negative side end portions of the capacitor electrode layers 560, 562, 564, and 566 in the y-axis direction. Is provided.

Further, a capacitor electrode layer 568 is formed on the dielectric layer 424e. The capacitor electrode layer 568 is formed with an electrode layer so as to overlap with the capacitor electrode layers 560, 562, 564, 566 and not to overlap with the coil axes of the coils L22, L23 when viewed in plan from the z-axis direction. It is formed to have no blanks.

The noise filter 410e having the above configuration has the circuit configuration shown in FIG. 21 in the same manner as the noise filter 410a.

According to the noise filter 410e, the capacitor electrode layers 550, 552, 554, 556, 558, 560, 562, 564, 566, and 568 do not overlap with the coils L21 to L24 when viewed in plan from the z-axis direction. Is formed. Therefore, in the noise filter 410e, the generation of eddy current loss in the capacitor electrode layers 550, 552, 554, 556, 558, 560, 562, 564, 566, and 568 is suppressed, and the magnetic flux generated in the coils L21 to L24 is strong. Become. As a result, the magnetic coupling between the coil L21 and the coil L22 and the magnetic coupling between the coil L23 and the coil L24 are strengthened, and the common mode noise removal characteristics of the noise filter 410e are improved as compared with the noise filter 410a.

(Fourteenth embodiment)
The configuration of the noise filter 410f according to the fourteenth embodiment will be described below with reference to the drawings. FIG. 41 is an exploded perspective view of the multilayer body 412f of the noise filter 410f according to the fourteenth embodiment. 41, the same components as those in FIGS. 20, 34 and 40 are denoted by the same reference numerals.

As shown in FIG. 41, the laminated body 412f is provided with

dielectric layers

416d, 416e, 416f, 424d, 424e, and 424f instead of the

dielectric layers

416a, 416b, 424a, and 424b. It differs from the laminate 412b shown in FIG. Hereinafter, differences between the stacked body 412f and the stacked body 412b will be described.

As shown in FIG. 41, in the stacked body 412f, a dielectric layer 416f is provided between the dielectric layer 414c and the dielectric layer 416d. Capacitor electrode layers 650, 652, 654, 656 are formed on the dielectric layer 416f. Capacitor electrode layers 650, 652, 654, and 656 are formed to overlap capacitor electrode layer 558 when viewed in plan from the z-axis direction. Thereby, capacitor electrode layer 650 and capacitor electrode layer 550 constitute capacitor C25. Capacitor electrode layer 652 and capacitor electrode layer 552 constitute capacitor C26. Capacitor electrode layer 654 and capacitor electrode layer 554 constitute capacitor C27. Capacitor electrode layer 656 and capacitor electrode layer 556 constitute capacitor C28. Furthermore, lead

portions

651, 653, 655, and 657 connected to the external electrodes E11, E13, E15, and E17, respectively, are provided at the ends on the positive side in the y-axis direction of the capacitor electrode layers 650, 652, 654, and 656. Is provided.

Further, capacitor electrode layers 660, 662, 664, 666 are formed on the dielectric layer 424f. The capacitor electrode layers 660, 662, 664, and 666 are formed so as to overlap with the capacitor electrode layer 568 when viewed in plan from the z-axis direction. Thereby, the capacitor electrode layer 660 and the capacitor electrode layer 560 constitute a capacitor C25. Capacitor electrode layer 662 and capacitor electrode layer 562 constitute capacitor C26. Capacitor electrode layer 664 and capacitor electrode layer 564 constitute capacitor C27. Capacitor electrode layer 666 and capacitor electrode layer 566 constitute capacitor C28. Further,

lead portions

661, 663, 665, and 667 connected to the external electrodes E11, E13, E15, and E17 are respectively provided at the ends on the positive side in the y-axis direction of the capacitor electrode layers 660, 662, 664, and 666. Is provided.

The noise filter 410f having the above configuration has the circuit configuration shown in FIG. 35, like the noise filter 410b.

According to the noise filter 410f, the capacitor electrode layers 558, 568, 650, 652, 654, 656, 660, 662, 664 and 666 do not overlap with the coils L21 to L24 when viewed in plan from the z-axis direction. Is formed. Therefore, in the noise filter 410f, the generation of eddy current loss in the capacitor electrode layers 558, 568, 650, 652, 654, 656, 660, 662, 664, and 666 is suppressed, and the magnetic flux generated in the coils L21 to L24 is strong. Become. As a result, the magnetic coupling between the coil L21 and the coil L22 and the magnetic coupling between the coil L23 and the coil L24 are strengthened, and the common mode noise removal characteristics of the noise filter 410f are improved as compared with the noise filter 410b.

(Fifteenth embodiment)
The configuration of the noise filter 410g according to the fifteenth embodiment will be described below with reference to the drawings. FIG. 42 is an exploded perspective view of the multilayer body 412g of the noise filter 410g according to the fifteenth embodiment. 42, the same components as those in FIGS. 20 and 38 are denoted by the same reference numerals.

As shown in FIG. 42, the laminate 412g is different from the

dielectric layers

416a, 416b, 424a, 424b in that

dielectric layers

416d, 416e, 424d, 424e are provided. It is different from 412d. The

dielectric layers

416d, 416e, 424d, and 424e are the same as those shown in FIG.

The noise filter 410g having the above configuration has the circuit configuration shown in FIG. 39, like the noise filter 410d.

According to the noise filter 410g, the capacitor electrode layers 550, 552, 554, 556, 558, 560, 562, 564, 566, and 568 do not overlap with the coils L21 to L24 when viewed in plan from the z-axis direction. Is formed. Therefore, in the noise filter 410g, the occurrence of eddy current loss in the capacitor electrode layers 550, 552, 554, 556, 558, 560, 562, 564, 566, and 568 is suppressed, and the magnetic flux generated in the coils L21 to L24 is strong. Become. As a result, the magnetic coupling between the coil L21 and the coil L22 and the magnetic coupling between the coil L23 and the coil L24 are strengthened, and the common mode noise removal characteristics of the noise filter 410g are improved as compared with the noise filter 410d.

(Sixteenth embodiment)
The configuration of the noise filter 410h according to the sixteenth embodiment will be described below with reference to the drawings. FIG. 43 is an exploded perspective view of the multilayer body 412h of the noise filter 410h according to the sixteenth embodiment. FIG. 44 is an equivalent circuit diagram of the noise filter 410h. 43 and 44, the same components as those in FIGS. 20 and 21 are denoted by the same reference numerals.

As shown in FIG. 43, the laminated body 412h is different from the laminated body 412a shown in FIG. 20 in that a dielectric layer 424g is provided between the dielectric layer 424a and the dielectric layer 426c. Hereinafter, differences between the stacked body 412h and the stacked body 412a will be described.

As shown in FIG. 43, in the stacked body 412h, a dielectric layer 424g is provided between the dielectric layer 424a and the dielectric layer 426c. Capacitor electrode layers 760, 762, 764, and 766 are formed on the dielectric layer 424g. Capacitor electrode layers 760, 762, 764, and 766 are formed so as to overlap capacitor electrode layers 460, 462, 464, and 466, respectively, when viewed in plan from the z-axis direction. Thereby, the capacitor electrode layer 460 and the capacitor electrode layer 760 constitute a capacitor C33. The capacitor electrode layer 462 and the capacitor electrode layer 762 constitute a capacitor C34. The capacitor electrode layer 464 and the capacitor electrode layer 764 constitute a capacitor C35. Capacitor electrode layer 466 and capacitor electrode layer 766 constitute capacitor C36. Furthermore, lead portions 761, 763, 765, and 767 connected to the external electrodes E11, E13, E15, and E17 are respectively provided at the ends on the positive side in the y-axis direction of the capacitor electrode layers 760, 762, 764, and 766. Is provided.

The noise filter 410h having the above configuration has a circuit configuration shown in FIG. More specifically, capacitors C33, C34, C35, and C36 are formed between both ends of the coils L21, L22, L23, and L24. The capacitances of the capacitors C33, C34, C35, and C36 can be adjusted by adjusting the shape and area of the capacitor electrode layers 760, 762, 764, and 766, and the common mode noise and normal mode noise of the noise filter 410h can be removed. The characteristics can be adjusted.

(Other embodiments)
Hereinafter, noise filters 410i to 410n according to other embodiments will be described with reference to the drawings. 45 to 47 are exploded perspective views of stacked bodies 412i to 412k of noise filters 410i to 410k according to other embodiments, respectively. FIG. 48 is an equivalent circuit diagram of the noise filter 410k of FIG. 49 to 51 are exploded perspective views of stacked bodies 412l to 412n of noise filters 410l to 410n according to other embodiments.

The noise filter 410i may include a stacked body 412i as shown in FIG. The noise filter 410i has the same equivalent circuit shown in FIG. 37 as the noise filter 410c shown in FIG.

Further, the noise filter 410j may include a laminated body 412j as shown in FIG. The noise filter 410j has the same equivalent circuit shown in FIG. 39 as the noise filter 410d shown in FIG.

Further, the noise filter 410k may include a laminated body 412k as shown in FIG. The noise filter 410k has an equivalent circuit shown in FIG. According to the noise filter 410k, a plurality of resonance points can be obtained in normal mode and common mode attenuation by inserting a solid signal pattern and adjusting magnetic coupling.

Further, the noise filters 410l to 410n may include stacked bodies 412l to 412n as shown in FIGS.

Although not described in detail in the tenth embodiment, the sixteenth embodiment, and other embodiments, in the noise filters 410b to 410n, as in the noise filter 410a, the coupling coefficient between the coil L21 and the coil L22 and The coupling coefficient between the coil L23 and the coil L24 is not less than 0.3 and not more than 0.7. Thereby, also in the noise filters 410b to 410n, the common mode noise countermeasure and the normal mode noise countermeasure can be taken between the driver and the receiver of the mobile phone, similarly to the noise filter 410a.

Note that the dielectric layer 424g may also be provided for the noise filters 410b to 410n.

The noise filters 410a to 410n may include one or more common mode choke coils.

(Electronic device)
Hereinafter, an electronic device including noise filters 410a to 410n will be described with reference to the drawings. FIG. 52 is a configuration diagram of an electronic device 600 including noise filters 410a to 410n. In the following description, it is assumed that the electronic device 600 includes the noise filter 410a. The electronic device 600 is, for example, a mobile phone. In FIG. 52, a part of the mobile phone or the like is extracted and described.

52, the electronic device 600 includes a noise filter 410a, drivers 602a and 602b, receivers 604a and 604b, and signal lines S1 to S8.

The driver 602a generates two signals having waveforms in opposite phases and outputs them to the signal lines S1 and S3. The signal lines S1 and S3 are connected to the external electrodes E11 and E13, respectively, and constitute a differential transmission path. The signal lines S2 and S4 are connected to the external electrodes E12 and E14, respectively, and constitute a differential transmission path. Thereby, the LC filter LC11 is connected between the signal line S1 and the signal line S2, and the LC filter LC12 is connected between the signal line S3 and the signal line S4. The receiver 604a is connected to the signal lines S2 and S4 constituting the differential transmission path, and detects a differential signal between the two signals transmitted through the signal lines S2 and S4.

The driver 602b generates two signals having waveforms with opposite phases, and outputs them to the signal lines S5 and S7. The signal lines S5 and S7 are connected to the external electrodes E15 and E17, respectively, and constitute a differential transmission path. The signal lines S6 and S8 are connected to the external electrodes E16 and E18, respectively, and constitute a differential transmission path. Thereby, the LC filter LC13 is connected between the signal line S5 and the signal line S6, and the LC filter LC14 is connected between the signal line S7 and the signal line S8. The receiver 604b is connected to the signal lines S6 and S8 constituting the differential transmission path, and detects a differential signal between the two signals transmitted through the signal lines S6 and S8.

According to the electronic apparatus 600, common mode noise is removed by the noise filters 410a to 410n. More specifically, the sum of the currents of two signals flowing through an ideal differential transmission line is constant. Therefore, normally, common mode noise does not occur in two signals flowing through the differential transmission path. However, in the differential transmission path, the amplitude and phase of the signals at the points D + and D− may be disrupted due to variations in impedance of the drivers 602a and 602b, and common mode noise may occur. Therefore, common mode noise is removed by inserting noise filters 410a to 410n between the drivers 602a and 602b and the receivers 604a and 604b.

Further, according to the electronic apparatus 600, normal mode noise is removed by the noise filters 410a to 410n. More specifically, in the noise filter 410a, the coupling coefficient between the coil L21 and the coil L22 and the coupling coefficient between the coil L23 and the coil L24 are 0.3 or more and 0.7 or less. It is possible to effectively remove normal mode noise generated in differential signals transmitted between the two.

INDUSTRIAL APPLICABILITY The present invention is useful for a noise filter and an electronic apparatus including the noise filter, and in particular, a common mode noise countermeasure and a normal mode noise between a driver and a receiver of a mobile phone while suppressing a deterioration in the quality of a differential signal waveform. It is excellent in that it is suitable for countermeasures.

Claims

A first common mode choke coil comprising two coils;
A first LC filter including a first coil;
A second LC filter including a second coil;
With
The two coils of the first common mode choke coil are also used as the first coil and the second coil;
Noise filter characterized by.
The first LC filter includes a first capacitor;
The second LC filter includes a second capacitor;
The first coil and the second coil are configured by laminating an insulating layer and a coil electrode layer,
The first capacitor and the second capacitor are configured by laminating an insulating layer and a capacitor electrode layer,
The insulating layer, the coil electrode layer, and the capacitor electrode layer are arranged such that the first coil and the second coil are positioned between the first capacitor and the second capacitor in the stacking direction. To be laminated,
The noise filter according to claim 1, wherein:
The first coil and the second coil have a structure in which current circulates in the same direction when viewed in plan from the stacking direction,
The noise filter according to claim 2, wherein:
The capacitor electrode layer includes a signal electrode formed so as not to overlap the coil axis of the first coil and the coil axis of the second coil when viewed in plan from the stacking direction;
The noise filter according to any one of claims 2 and 3, wherein:
The magnitudes of magnetic flux generated by the first coil and the second coil are substantially equal;
The noise filter according to claim 3, wherein:
The capacitor electrode layer has a substantially line-symmetric structure with respect to a boundary line between the first LC filter and the second LC filter;
The noise filter according to claim 4, wherein:
The capacitor electrode layer includes a ground electrode formed so as not to overlap the coil axis of the first coil and the coil axis of the second coil when viewed in plan from the stacking direction;
The noise filter according to any one of claims 2 to 6, wherein:
A third LC filter comprising a third coil and a third capacitor;
A fourth LC filter comprising a fourth coil and a fourth capacitor;
A second common mode choke coil comprising two coils;
Further comprising
The third coil and the fourth coil are also used as two coils of the second common mode choke coil;
The noise filter according to any one of claims 1 to 7, characterized by the above.
The third LC filter and the fourth LC filter are not electrically connected to the first LC filter and the second LC filter;
The noise filter according to claim 8, wherein:
The first coil is capacitively coupled to the third coil and / or the fourth coil;
The noise filter according to any one of claims 8 and 9, wherein:
The third coil and the fourth coil are configured by laminating an insulating layer and a coil electrode layer,
The third capacitor and the fourth capacitor are configured by laminating an insulating layer and a capacitor electrode layer,
The insulating layer, the coil electrode layer, and the capacitor electrode layer are arranged such that the third coil and the fourth coil are positioned between the third capacitor and the fourth capacitor in the stacking direction. To be laminated,
The noise filter according to claim 10, wherein:
A coupling electrode layer laminated with the insulating layer and capacitively coupling the first coil and the third coil;
To provide further,
The noise filter according to claim 11, wherein:
The coupling electrode layer is formed between the first LC filter and the third LC filter when viewed in plan from the stacking direction;
The noise filter according to claim 12, wherein:
The coupling electrode layer has a coil axis of the first coil, a coil axis of the second coil, a coil axis of the third coil, and a coil of the fourth coil when viewed in plan from the stacking direction. Be formed so as not to overlap the shaft,
The noise filter according to claim 13, wherein:
A capacitor electrode for forming a fifth capacitor at both ends of the first coil;
The noise filter according to any one of claims 1 to 14, wherein:
A first common mode choke coil composed of two coils coupled with a coupling coefficient of 0.3 to 0.7;
A first LC filter including a first coil;
A second LC filter including a second coil;
With
The two coils of the first common mode choke coil are also used as the first coil and the second coil;
Noise filter characterized by.
The coupling coefficient of the first common mode choke coil is not less than 0.3 and not more than 0.6;
The noise filter according to claim 16, wherein:
The first LC filter includes a first capacitor;
The second LC filter includes a second capacitor;
The first coil and the second coil are configured by laminating an insulating layer and a coil electrode layer,
The first capacitor and the second capacitor are configured by laminating an insulating layer and a capacitor electrode layer,
The insulating layer, the coil electrode layer, and the capacitor electrode layer are arranged such that the first coil and the second coil are positioned between the first capacitor and the second capacitor in the stacking direction. To be laminated,
The noise filter according to any one of claims 16 and 17, characterized by the above.
The first coil and the second coil have a structure in which current circulates in the same direction when viewed in plan from the stacking direction,
The noise filter according to claim 18, wherein:
The capacitor electrode layer includes a signal electrode formed so as not to overlap the coil axis of the first coil and the coil axis of the second coil when viewed in plan from the stacking direction;
20. The noise filter according to claim 18, wherein the noise filter is characterized by the following.
The magnitudes of magnetic flux generated by the first coil and the second coil are substantially equal;
The noise filter according to claim 19, wherein:
The capacitor electrode layer has a substantially line-symmetric structure with respect to a boundary line between the first LC filter and the second LC filter;
21. The noise filter according to claim 20, wherein:
The capacitor electrode layer includes a ground electrode formed so as not to overlap the coil axis of the first coil and the coil axis of the second coil when viewed in plan from the stacking direction;
The noise filter according to any one of claims 18 to 22, characterized by the above-mentioned.
A third LC filter comprising a third coil and a third capacitor;
A fourth LC filter comprising a fourth coil and a fourth capacitor;
A second common mode choke coil composed of two coils coupled with a coupling coefficient of 0.3 or more and 0.7 or less;
Further comprising
The third coil and the fourth coil are also used as two coils of the second common mode choke coil;
The noise filter according to any one of claims 16 to 23.
The coupling coefficient of the first common mode choke coil is not less than 0.3 and not more than 0.6;
25. The noise filter according to claim 24, wherein:
The third LC filter and the fourth LC filter are not electrically connected to the first LC filter and the second LC filter;
26. A noise filter according to claim 24 or claim 25, wherein:
The first coil is capacitively coupled to the third coil and / or the fourth coil;
27. The noise filter according to any one of claims 24 to 26, wherein:
The third coil and the fourth coil are configured by laminating an insulating layer and a coil electrode layer,
The third capacitor and the fourth capacitor are configured by laminating an insulating layer and a capacitor electrode layer,
The insulating layer, the coil electrode layer, and the capacitor electrode layer are arranged such that the third coil and the fourth coil are positioned between the third capacitor and the fourth capacitor in the stacking direction. To be laminated,
28. The noise filter according to claim 27.
A coupling electrode layer laminated with the insulating layer and capacitively coupling the first coil and the third coil;
To provide further,
26. The noise filter according to claim 25, wherein:
The coupling electrode layer is formed between the first LC filter and the third LC filter when viewed in plan from the stacking direction;
30. A noise filter according to claim 29, wherein:
The coupling electrode layer has a coil axis of the first coil, a coil axis of the second coil, a coil axis of the third coil, and a coil of the fourth coil when viewed in plan from the stacking direction. Be formed so as not to overlap the shaft,
The noise filter according to claim 30, wherein:
A capacitor electrode for forming a fifth capacitor at both ends of the first coil;
32. The noise filter according to claim 16, wherein the noise filter is any one of claims 16 to 31.
A noise filter according to claim 16,
A differential transmission line comprising a first signal line to a fourth signal line;
With
The first LC filter is connected between the first signal line and the second signal line,
The second LC filter is connected between the third signal line and the fourth signal line;
An electronic device characterized by the above.
The noise filter according to claim 24,
A differential transmission path comprising a first signal line to an eighth signal line;
The first LC filter is connected between the first signal line and the second signal line,
The second LC filter is connected between the third signal line and the fourth signal line,
The third LC filter is connected between the fifth signal line and the sixth signal line;
The fourth LC filter is connected between the seventh signal line and the eighth signal line;
An electronic device characterized by the above.