JP2007159069A - Layered common mode filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a layered common mode filter is not available for a communication apparatus which performs high-speed differential transmission since a loss of ferrite becomes great in a high frequency band of GHz, an insertion loss to a differential signal to be transmitted also tends to be great therefore, and a differential signal to be transmitted may be attenuated. <P>SOLUTION: An insulator layer and a conductor pattern are layered. In a layered body thereof, provided are a first coil connected between a first terminal and a second terminal, a second coil connected between a third terminal and a fourth terminal, a first capacitor connected in parallel with the first coil, a second capacitor connected in parallel with the second coil, a third capacitor connected between a winding start terminal of the first coil and a winding start terminal of the second coil, and a fourth capacitor connected between a winding end terminal of the first coil and a winding end terminal of the second coil, and the first coil and the second coil are magnetically coupled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminated common mode filter having a plurality of coils in which an insulating layer and a conductor pattern are laminated and magnetically coupled to each other in the laminated body.

As shown in FIG. 12, a conventional common mode choke coil is formed by winding a pair of copper wires arranged in parallel and winding them around a ferrite core and connecting the ends of each copper wire to a terminal. There is a circuit in which the coil L7 is connected between the terminal 121 and the terminal 122, the coil L8 is connected between the terminal 123 and the terminal 124, and a circuit in which the coil L7 and the coil L8 are magnetically coupled is configured (for example, Patent Documents). 1).
JP 2004-356473 A

  This type of common mode choke coil has a ferrite permeability μ that decreases as the frequency increases. Therefore, common mode noise can be removed from several KHz to several GHz, and communication device interfaces (USB2.0, IEEE1394) and Used for PCI bus transmission lines. In recent years, a PCI Express specification has been announced on the PCI bus, and data transmission / reception is performed using serial data (differential signal) with an operating frequency of 2.5 GHz.

  However, the conventional common mode choke coil has a large loss of ferrite in a high frequency band such as GHz, so that the insertion loss with respect to the transmitted differential signal tends to increase, and the differential signal that needs to be transmitted is attenuated. In other words, it cannot be used for communication devices that perform high-speed differential transmission as described above.

  An object of the present invention is to provide a small stacked common mode filter having a low insertion loss for a required signal even in a high frequency band such as GHz.

The laminated common mode filter of the present invention comprises an insulator layer and a conductor pattern laminated, and a first coil and a third terminal connected between the first terminal and the second terminal in the laminated body. The second coil connected between the fourth terminals, the first capacitor connected in parallel with the first coil, the second capacitor connected in parallel with the second coil, the winding of the first coil A third capacitor connected between the starting end and the winding start end of the second coil; and a fourth capacitor connected between the winding end end of the first coil and the winding end end of the second coil. The first coil and the second coil are magnetically coupled.
The multilayer common mode filter of the present invention includes an insulator layer and a conductor pattern, and includes four capacitors and two coils spirally wound around a common winding axis in the multilayer body. The two coils are arranged so as to overlap in the stacking direction so that the winding start sides are close to each other, the first coil is connected between the first terminal and the second terminal, and the third terminal and the fourth terminal A second coil is connected in between, a first capacitor is connected in parallel with the first coil, a second capacitor is connected in parallel with the second coil, and the winding end of the first coil and the second coil A fourth capacitor is connected between the winding end ends of the two coils, and the winding of the first coil is started by the capacitance formed between the winding start end portion of the first coil and the winding start end portion of the second coil. A third condenser between the end and the winding start end of the second coil. There is connected.
Furthermore, the multilayer common mode filter of the present invention includes an insulator layer and a conductor pattern, and includes four capacitors and two coils spirally wound around a common winding axis in the laminate. The two coils are arranged to overlap in the stacking direction so that the winding end sides are close to each other, the first coil is connected between the first terminal and the second terminal, and the third terminal and the fourth terminal A second coil is connected in between, a first capacitor is connected in parallel with the first coil, a second capacitor is connected in parallel with the second coil, and the winding start end of the first coil and the second coil A third capacitor is connected between the winding start ends of the two coils, and a winding end of the first coil is formed by a capacitance formed between the winding end end of the first coil and the winding end end of the second coil. Between the end and the end of winding of the second coil Capacitor is connected.

  The multilayer common mode filter of the present invention includes a first coil connected between a first terminal and a second terminal, and a third terminal and a fourth terminal in a laminate of an insulator layer and a conductor pattern. A second capacitor connected in parallel, a first capacitor connected in parallel with the first coil, a second capacitor connected in parallel with the second coil, a winding start end of the first coil and the second A third capacitor connected between the winding start ends of the first coil and a fourth capacitor connected between the winding end end of the first coil and the winding end end of the second coil, And the second coil are magnetically coupled to each other, so that the shape can be reduced in size and the amount of unnecessary noise attenuation can be improved without increasing the insertion loss for a necessary signal even in a high frequency band.

In the multilayer common mode filter of the present invention, an insulator layer and a conductor pattern are laminated, and four capacitors and two coils wound spirally around a common winding axis are formed in these laminates. . The two coils are arranged so as to overlap in the stacking direction so that the winding start sides are close to each other, the first coil is connected between the first terminal and the second terminal, and between the third terminal and the fourth terminal Is connected to the second coil. A first capacitor is connected in parallel to the first coil. A second capacitor is connected in parallel to the second coil. Further, a fourth capacitor is connected between the winding end of the first coil and the winding end of the second coil. A third capacitor is connected between the winding start end of the first coil and the winding start end of the second coil by a capacitance formed between the conductive patterns on the winding start side of the two coils.
In addition, the two coils of another laminated common mode filter of the present invention are arranged so as to overlap each other in the lamination direction so that the winding end sides are close to each other, and the first coil is interposed between the first terminal and the second terminal. The second coil is connected between the third terminal and the fourth terminal. A first capacitor is connected in parallel to the first coil. A second capacitor is connected in parallel to the second coil. In this case, a third capacitor is connected between the winding start end of the first coil and the winding start end of the second coil. A fourth capacitor is connected between the winding end of the first coil and the winding end of the second coil by a capacitance formed between the conductive patterns on the winding end of the two coils. .
Therefore, the multilayer common mode filter of the present invention adjusts the inductance value of the two coils, the capacitance value of the four capacitors, and the magnetic coupling coefficient of the two coils to adjust the differential signal that needs to be transmitted. It is possible to form an attenuation pole for attenuating noise (in-phase signal) unnecessary for the frequency band.

Hereinafter, the laminated common mode filter of the present invention will be described with reference to FIGS.
1 is a circuit diagram of a multilayer common mode filter of the present invention, FIG. 2 is an exploded perspective view of a first embodiment of the multilayer common mode filter of the present invention, and FIG. It is a perspective view of 1 Example.
The coil L1 is connected between the first terminal 11 and the second terminal 12. The coil L <b> 2 is connected between the third terminal 13 and the fourth terminal 14. The coil L1 and the coil L2 have the same inductance value and are magnetically positively coupled to each other.
The capacitor C1 is connected in parallel with the coil L1. The capacitor C2 is connected in parallel with the coil L2.
The capacitor C3 is connected between the winding start end of the coil L1 and the winding start end of the coil L2. Capacitor C4 is connected between the winding end of coil L1 and the winding end of coil L2.

Such a common mode filter is formed in a laminated body by laminating an insulator layer and a conductor pattern as shown in FIG.
The insulating layers 21A to 21J are formed using an insulating material such as a magnetic material, a nonmagnetic material, or a dielectric material.
The capacitor conductor pattern 22A and the capacitor conductor pattern 23A are formed on the surface of the insulator layer 21A so as not to contact each other. The lead end of the capacitor conductor pattern 22A and the lead end of the capacitor conductor pattern 23A are drawn to the same side surface of the insulating layer 21A.
A capacitor conductor pattern 22B, a capacitor conductor pattern 23B, and a capacitor conductor pattern 24 are formed on the surface of the insulating layer 21B so as not to contact each other. The capacitor conductor pattern 22B is formed at a position facing the capacitor conductor pattern 22A. The capacitor conductor pattern 23B is formed at a position facing the capacitor conductor pattern 23A. Further, the capacitor conductor pattern 24 is formed at a position facing both the capacitor conductor pattern 22A and the capacitor conductor pattern 23A. The lead end of the capacitor conductor pattern 22B and the lead end of the capacitor conductor pattern 23B are drawn to the same side surface of the insulator layer 21B.
A coil conductor pattern 25A is formed on the surface of the insulator layer 21C. One end of the coil conductor pattern 25A is drawn to the side surface of the insulating layer 21C.
A coil conductor pattern 25B is formed on the surface of the insulating layer 21D. One end of the coil conductor pattern 25B is connected to the other end of the coil conductor pattern 25A via a conductor in the through hole of the insulator layer 21D.
A coil conductor pattern 25C is formed on the surface of the insulator layer 21E. One end of the coil conductor pattern 25C is connected to the other end of the coil conductor pattern 25B via a conductor in the through hole of the insulator layer 21E. The other end of the coil conductor pattern 25C is drawn to the side surface of the insulator layer 21E. In this way, the coil L1 is formed by connecting the coil conductor patterns 25A to 25C in a spiral shape. In the coil L1, the coil conductor pattern 25C formed on the surface of the insulator layer 21E constitutes the winding start end, and the coil conductor pattern 25A formed on the surface of the insulator layer 21C has the winding end end. Constitute.
A coil conductor pattern 26A is formed on the surface of the insulator layer 21F. The coil conductor pattern 26A is formed at the position facing the coil conductor pattern 25C so that the winding direction of the coil conductor pattern 25C is the same. One end of the coil conductor pattern 26A is drawn to the side surface of the insulating layer 21F.
A coil conductor pattern 26B is formed on the surface of the insulator layer 21G. One end of the coil conductor pattern 26B is connected to the other end of the coil conductor pattern 26A via a conductor in the through hole of the insulator layer 21G.
A coil conductor pattern 26C is formed on the surface of the insulator layer 21H. One end of the coil conductor pattern 26C is connected to the other end of the coil conductor pattern 26B via a conductor in the through hole of the insulator layer 21H. The other end of the coil conductor pattern 26C is drawn to the side surface of the insulator layer 21H. In this way, the coil L2 is formed by connecting the coil conductor patterns 26A to 26C in a spiral shape. The coil L2 is stacked such that its winding axis coincides with the winding axis of the coil L1, and is wound in the same direction as the winding direction of the coil L1. In the coil L2, the coil conductor pattern 26A formed on the surface of the insulator layer 21F constitutes a winding start end, and the coil conductor pattern 26C formed on the surface of the insulator layer 21H has a winding end. Parts.
A magnetic shield conductor pattern 27 is formed on the surface of the insulator layer 21I.
In this way, the insulator layers 21A to 21I are sequentially laminated, and the terminal electrodes 31, 32, 33, and 34 are formed on the side surfaces of the laminate covered with the protective insulator layer 21J as shown in FIG. Is formed. The other end of the coil conductor pattern 25C and the lead end of the capacitor conductor pattern 22B are connected to the terminal electrode 31, and one end of the coil conductor pattern 25A and the lead end of the capacitor conductor pattern 22A are connected to the terminal electrode 32. Thus, the parallel circuit of the coil L1 and the capacitor C1 is connected between the first terminal 11 and the second terminal 12. One end of the coil conductor pattern 26A and the lead end of the capacitor conductor pattern 23B are connected to the terminal electrode 33, and the other end of the coil conductor pattern 26C and the lead end of the capacitor conductor pattern 23A are connected to the terminal electrode 34. Thus, the parallel circuit of the coil L2 and the capacitor C2 is connected between the third terminal 13 and the fourth terminal 14. Further, the capacitor formed between the coil conductor pattern 22A and the capacitor conductor pattern 24 and between the winding end of the coil L1 and the winding end of the coil L2 depending on the capacitance formed between the capacitor conductor pattern 23A and the capacitor conductor pattern 24. C4 is connected. Furthermore, the capacitor C3 is connected between the winding start end of the coil L1 and the winding start end of the coil L2 by the capacitance formed between the coil conductor pattern 25C and the coil conductor pattern 26A.

  In the laminated common mode filter formed in this way, a dielectric having a dielectric constant of 4.6 is used for the insulator layers 21A to 21J, and the line widths of the coil conductor patterns 25A, 25B, 25C, 26A, 26B, and 26C are used. The coil L1 and the coil L2 having the same inductance value are formed with a thickness of 75 μm, and are magnetically coupled to each other in a state where the winding start end of the coil L1 and the winding start end of the coil L2 are close to each other. When the thickness was set to 0.0 × 1.2 × 0.8 mm, the characteristics shown in FIGS. 4A and 4B were obtained. In FIG. 4, the horizontal axis represents frequency, the vertical axis represents attenuation, 41 represents differential signal attenuation, 42 represents in-phase signal (noise) attenuation, 43 represents reflected signal attenuation, and 44 represents Common mode rejection ratio, 45 indicates SCD21 (noise attenuation to the outside), and 46 indicates SDC21 (noise attenuation from the outside). Looking at these characteristics at a PCI Express clock frequency of 2.5 GHz, as shown in FIG. 5, the differential insertion loss is 0.459 dB, the differential reflection loss is 26.12 dB, and the noise attenuation is 31. 84dB, common mode rejection ratio is 36.83dB, SCD21 is 32.75dB, SDC21 is 39.67dB, and the amount of noise attenuation is reduced with the differential insertion loss reduced to 1/2 or less compared to the conventional one. Was improved by 20%.

FIG. 6 is an exploded perspective view of a second embodiment of the multilayer common mode filter of the present invention.
A capacitor conductor pattern 62A, a capacitor conductor pattern 62B, a capacitor conductor pattern 63A, and a capacitor conductor pattern 63B are formed on the surface of the insulator layer 61A. The capacitor conductor pattern 62A and the capacitor conductor pattern 62B are formed so as not to contact each other on one half surface (the left half surface in FIG. 6) of the insulator layer 61A, and each lead end is the same as that of the insulator layer 61A. It is pulled out to the side. Further, the capacitor conductor pattern 63A and the capacitor conductor pattern 63B are formed so as not to contact each other on the remaining half surface (the right half surface in FIG. 6) of the insulator layer 61A, and each lead-out end is an insulator layer. It is pulled out to the same side of 61A. At this time, the capacitor conductor patterns 62A and 62B and the capacitor conductor patterns 63A and 63B are formed point-symmetrically with the center of the surface of the insulator layer 61A as the origin, and the lead ends of the capacitor conductor patterns 62A and 62B The lead ends of the capacitor conductive patterns 63A and 63B are drawn to different side surfaces of the insulating layer 61A.
A capacitor conductor pattern 62C, a capacitor conductor pattern 62D, a capacitor conductor pattern 62E, a capacitor conductor pattern 63C, a capacitor conductor pattern 63D, and a capacitor conductor pattern 63E are formed on the surface of the insulator layer 61B. The capacitor conductor pattern 62C, the capacitor conductor pattern 62D, and the capacitor conductor pattern 62E are formed so as not to contact each other on one half surface (left half surface in FIG. 6) of the insulator layer 61B, and the capacitor conductor pattern 62C. And the lead end of the capacitor conductive pattern 62D are drawn to the same side surface of the insulating layer 61B. The capacitor conductor pattern 63C, the capacitor conductor pattern 63D, and the capacitor conductor pattern 63E are formed so as not to contact each other on the remaining half surface (the right half surface in FIG. 6) of the insulator layer 61B. The lead end of the conductor pattern 63C and the lead end of the capacitor conductor pattern 63D are drawn to the same side surface of the insulator layer 61B. At this time, the lead-out ends of the capacitor conductor patterns 62C and 62D and the lead-out ends of the capacitor conductor patterns 63C and 63D are drawn to different side surfaces of the insulating layer 61B. In this way, the capacitor conductor patterns 62C, 62D, and 62E and the capacitor conductor patterns 63C, 63D, and 63E are formed point-symmetrically with the center of the surface of the insulator layer 61B as the origin.
A coil conductor pattern 64A and a coil conductor pattern 65A are formed on the surface of the insulating layer 61C. The coil conductor pattern 64A is formed on one half surface (left half surface in FIG. 6) of the insulating layer 61C. The coil conductor pattern 65A is formed on the remaining half surface (the right half surface in FIG. 6) of the insulating layer 61C. One end of the coil conductor pattern 64A and one end of the coil conductor pattern 65A are drawn out to different side surfaces of the insulator layer 61C.
A coil conductor pattern 64B and a coil conductor pattern 65B are formed on the surface of the insulator layer 61D. The coil conductor pattern 64B is formed on one half surface (left half surface in FIG. 6) of the insulating layer 61D, and one end thereof is connected to the other end of the coil conductor pattern 64A. The coil conductor pattern 65B is formed on the remaining half surface (the right half surface in FIG. 6) of the insulator layer 61D, and one end thereof is connected to the other end of the coil conductor pattern 65A.
A coil conductor pattern 64C and a coil conductor pattern 65C are formed on the surface of the insulator layer 61E. The coil conductor pattern 64C is formed on one half surface (left half surface in FIG. 6) of the insulating layer 61E, and one end thereof is connected to the other end of the coil conductor pattern 64B. The coil conductor pattern 65C is formed on the remaining half surface (the right half surface in FIG. 6) of the insulating layer 61E, and one end thereof is connected to the other end of the coil conductor pattern 65B. The other end of the coil conductor pattern 64C and the other end of the coil conductor pattern 65C are drawn out to different side surfaces of the insulator layer 61E. Thus, the coil L3 is formed by connecting the coil conductor pattern 64A to the coil conductor pattern 64C in a spiral shape, and the coil L6 is formed by connecting the coil conductor pattern 65A to the coil conductor pattern 65C in a spiral shape. It is formed. In the coil L3, the coil conductor pattern 64C formed on the surface of the insulator layer 61E constitutes the winding start end, and the coil conductor pattern 64A formed on the surface of the insulator layer 61C has the winding end end. Constitute. In the coil L6, the coil conductor pattern 65C formed on the surface of the insulator layer 61E constitutes the winding start end, and the coil conductor pattern 65A formed on the surface of the insulator layer 61C has the winding end end. Configure.
A coil conductor pattern 66A and a coil conductor pattern 67A are formed on the surface of the insulating layer 61F. The coil conductor pattern 66A is formed on one half surface (left half surface in FIG. 6) of the insulator layer 61F at a position facing the coil conductor pattern 64C so as to be in the same winding direction as the coil conductor pattern 64C. Is done. Further, the coil conductor pattern 67A has the same winding direction as the coil conductor pattern 65C at the position facing the coil conductor pattern 65C on the remaining half surface (the right half surface in FIG. 6) of the insulating layer 61F. Formed. One end of the coil conductor pattern 66A and one end of the coil conductor pattern 67A are drawn out to different side surfaces of the insulator layer 61F.
A coil conductor pattern 66B and a coil conductor pattern 67B are formed on the surface of the insulator layer 61G. The coil conductor pattern 66B is formed on one half surface (left half surface in FIG. 6) of the insulator layer 61G, and one end thereof is connected to the other end of the coil conductor pattern 66A. The coil conductor pattern 67B is formed on the remaining half surface (the right half surface in FIG. 6) of the insulating layer 61G, and one end thereof is connected to the other end of the coil conductor pattern 67A.
A coil conductor pattern 66C and a coil conductor pattern 67C are formed on the surface of the insulating layer 61H. The coil conductor pattern 66C is formed on one half surface (left half surface in FIG. 6) of the insulating layer 61H, and one end thereof is connected to the other end of the coil conductor pattern 66B. The coil conductor pattern 67C is formed on the remaining half surface (the right half surface in FIG. 6) of the insulating layer 61H, and one end thereof is connected to the other end of the coil conductor pattern 67B. The other end of the coil conductor pattern 66C and the other end of the coil conductor pattern 67C are drawn out to different side surfaces of the insulator layer 61H. In this way, the coil L4 is formed by connecting the coil conductor patterns 66A to 66C in a spiral shape, and the coil L5 is formed by connecting the coil conductor patterns 67A to 67C in a spiral shape. The coil L4 is stacked so that its winding axis coincides with the winding axis of the coil L3, and is wound in the same direction as the winding direction of the coil L3. In the coil L4, the coil conductor pattern 66A on the surface of the insulator layer 61F constitutes a winding start end portion, and the coil conductor pattern 66C on the surface of the insulator layer 61F constitutes a winding end end portion. The coil L5 is stacked so that its winding axis coincides with the winding axis of the coil L6, and is wound in the same direction as the winding direction of the coil L6. In the coil L5, the coil conductor pattern 67A on the surface of the insulator layer 61F constitutes the winding start end portion, and the coil conductor pattern 67C on the surface of the insulator layer 61H constitutes the winding end end portion.
A magnetic shield conductor pattern 68A and a magnetic shield conductor pattern 68B are formed on the surface of the insulator layer 61I.
In this way, by sequentially laminating from the insulator layer 61A to the insulator layer 61I and covering with the protective insulator layer 61J, a circuit as shown in FIG. Terminal electrodes 81 to 87 are formed on the side surfaces as shown in FIG. The coil conductor pattern 64C and the capacitor conductor pattern 62C are connected to the terminal electrode 81, and the coil conductor pattern 64A and the capacitor conductor pattern 62A are connected to the terminal electrode 82, whereby the coil L3 and the capacitor C5 are parallel. A circuit is connected between the first terminal 71 and the second terminal 72. Further, the coil conductor pattern 66A and the capacitor conductor pattern 62D are connected to the terminal electrode 83, and the coil conductor pattern 66C and the capacitor conductor pattern 62B are connected to the terminal electrode 84, whereby the coil L4 and the capacitor C6 are arranged in parallel. A circuit is connected between the third terminal 73 and the fourth terminal 74. Further, a capacitor is formed between the winding end of the coil L3 and the winding end of the coil L4 by the capacitance formed between the capacitor conductive pattern 62A and the capacitor conductive pattern 62E and between the capacitor conductive pattern 62B and the capacitor conductive pattern 62E. C8 is connected. Furthermore, the capacitor C7 is connected between the winding start end of the coil L3 and the winding start end of the coil L4 by the capacitance formed between the coil conductor pattern 64C and the coil conductor pattern 66A. Further, the coil conductor pattern 67A and the capacitor conductor pattern 63C are connected to the terminal electrode 85, and the coil conductor pattern 67C and the capacitor conductor pattern 63A are connected to the terminal electrode 86, so that the coil L5 and the capacitor C9 are arranged in parallel. A circuit is connected between the fifth terminal 75 and the sixth terminal 76. Furthermore, the coil conductor pattern 65C and the capacitor conductor pattern 63D are connected to the terminal electrode 87, and the coil conductor pattern 65A and the capacitor conductor pattern 63B are connected to the terminal electrode 88, whereby the coil L6 and the capacitor C10 are parallel. A circuit is connected to the seventh terminal 77 and the eighth terminal 78. Further, the capacitor formed between the winding end of the coil L5 and the winding end of the coil L6 depending on the capacitance formed between the capacitor conductive pattern 63A and the capacitor conductive pattern 63E and between the capacitor conductive pattern 63B and the capacitor conductive pattern 63E. C12 is connected. Furthermore, the capacitor C11 is connected between the winding start end of the coil L5 and the winding start end of the coil L6 by the capacitance formed between the coil conductor pattern 65C and the coil conductor pattern 67A. This circuit is a circuit comprising two sets of the circuit shown in FIG. 1, and has a circuit configuration suitable for PCI Express having two high-speed differential transmission lines for transmission and reception. In the mode filter TX, the reception-side common mode filter RX is formed in the remaining half of the stacked body.

  In the laminated common mode filter formed as described above, dielectric materials having a dielectric constant of 4.6 are used for the insulator layers 61A to 61J, and coil conductor patterns 64A to 64C, 65A to 65C, 66A to 66C, and 67A to 67A. The coils L3, L4, L5, and L6 are formed with a line width of 67C of 75 μm and are magnetically coupled to each other in a state where the winding start end of the coil L3 and the winding start end of the coil L4 are close to each other. When the start end and the winding start end of the coil L6 are close to each other, they are magnetically coupled to each other, and the overall size is 2.0 × 1.2 × 0.8 mm. The filter circuit can be formed integrally, and the receiving side characteristics as shown in FIG. 9 and the transmitting side characteristics as shown in FIG. 10 are obtained. In FIG. 9, the horizontal axis represents frequency, the vertical axis represents attenuation, 91 represents the attenuation of the differential signal on the reception side, 92 represents the attenuation of the in-phase signal (noise) on the reception side, and 93 represents the differential signal on the reception side. , 94 represents the common mode rejection ratio, 95 represents SCD21 (noise attenuation to the outside), and 96 represents SDC21 (noise attenuation from the outside). In FIG. 10, the horizontal axis represents frequency, the vertical axis represents attenuation, 101 represents the attenuation of the differential signal, 102 represents the attenuation of the in-phase signal (noise), 103 represents the attenuation of the reflected wave of the differential signal, and 104 represents Common mode rejection ratio, 105 is SCD21 (noise attenuation to the outside), and 106 is SDC21 (noise attenuation from the outside). In addition, the electrical separation between the transmission and reception at this time is as shown in FIG. 11, and 35 dB or more could be secured. In FIG. 11, the horizontal axis represents frequency, the vertical axis represents attenuation, 111 represents the degree of separation between the input terminal on the reception side and the input terminal on the transmission side, and 112 represents separation between the input terminal on the reception side and the output terminal on the transmission side. 113 indicates the degree of separation between the output end on the reception side and the input end on the transmission side, and 114 indicates the degree of separation between the output end on the reception side and the output end on the transmission side.

  As mentioned above, although the Example of the laminated | stacked common mode filter of this invention was described, it is not restricted to these Examples. For example, two coils that are magnetically coupled to each other are arranged so as to overlap each other in the stacking direction with the winding end sides being close to each other, and the first coil is connected between the first terminal and the second terminal, A second coil is connected between the third terminal and the fourth terminal, a first capacitor is connected in parallel with the first coil, a second capacitor is connected in parallel with the second coil, A third capacitor is connected between the winding start end of the first coil and the winding start end of the second coil, and is formed between the winding end end of the first coil and the winding end end of the second coil. A fourth capacitor may be connected between the winding end of the first coil and the winding end of the second coil depending on the capacitance.

FIG. 3 is a circuit diagram of the multilayer common mode filter of the present invention. It is a disassembled perspective view of the 1st Example of the lamination type common mode filter of the present invention. It is a perspective view of the 1st example of the lamination type common mode filter of the present invention. It is a characteristic view of the 1st Example of the lamination type common mode filter of this invention. It is the table | surface which compared the characteristic of the 1st Example of the laminated | stacked common mode filter of this invention, and the characteristic of the conventional common mode filter. It is a disassembled perspective view of 2nd Example of the laminated | stacked common mode filter of this invention. It is a circuit diagram of the 2nd example of a lamination type common mode filter of the present invention. It is a perspective view of the 2nd example of the lamination type common mode filter of the present invention. It is a characteristic view of the 2nd example of the lamination type common mode filter of the present invention. It is a characteristic view of the 2nd example of the lamination type common mode filter of the present invention. It is a characteristic view of the 2nd example of the lamination type common mode filter of the present invention. This is a conventional common mode choke coil.

Explanation of symbols

11 1st terminal 12 2nd terminal 13 3rd terminal 14 4th terminal L1 1st coil L2 2nd coil C1 1st capacitor C2 2nd capacitor C3 3rd capacitor C4 4th capacitor

Claims (4)

  The insulator layer and the conductor pattern are laminated, and in these laminates, the first coil connected between the first terminal and the second terminal, and the first coil connected between the third terminal and the fourth terminal. Two coils, a first capacitor connected in parallel with the first coil, a second capacitor connected in parallel with the second coil, a winding start end of the first coil, and the second coil A third capacitor connected between the winding start ends of the coil, and a fourth capacitor connected between the winding end end of the first coil and the winding end end of the second coil, A laminated common mode filter characterized by magnetically coupling the second coil and the second coil.   An insulating layer and a conductor pattern are stacked, and four capacitors and two coils wound spirally around a common winding axis are provided in the stacked body, and the two coils are close to each other at the winding start side. The first coil is connected between the first terminal and the second terminal, and the second coil is connected between the third terminal and the fourth terminal. The first capacitor is connected in parallel with the first coil, the second capacitor is connected in parallel with the second coil, the winding end of the first coil and the winding of the second coil A fourth capacitor is connected between the end ends, and a winding start end of the first coil is formed by a capacitance formed between the winding start end of the first coil and the winding start end of the second coil. A third capacitor is connected between the winding start ends of the second coil. Multilayer common mode filter to.   An insulator layer and a conductor pattern are laminated, and four capacitors and two coils spirally wound around a common winding axis are provided in the laminate, and the two coils are close to each other at the winding end side. The first coil is connected between the first terminal and the second terminal, and the second coil is connected between the third terminal and the fourth terminal. A first capacitor connected in parallel with the first coil, a second capacitor connected in parallel with the second coil, and a winding start end of the first coil and a winding of the second coil. A third capacitor is connected between the start ends, and a winding end of the first coil is formed by a capacitance formed between the end of winding of the first coil and the end of winding of the second coil. A fourth capacitor is connected between the winding ends of the second coil. Multilayer common mode filter according to claim.   The multilayer common mode filter according to any one of claims 1 to 3, wherein an array of common mode filters is formed by forming a plurality of sets of the four capacitors and two coils in the multilayer body.

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