Common mode noise filters

Abstract

A common-mode noise filter comprises: a laminate comprising first to fourth insulating layers stacked in sequence; first and second coils provided on the laminate; and a conductor layer provided on the laminate. The first coil comprises a first spiral conductor provided on the lower surface of the first insulating layer; and a second spiral conductor provided on the upper surface of the second insulating layer. The second coil comprises a third spiral conductor provided on the upper surface of the first insulating layer, opposing the first spiral conductor with the first insulating layer interposed therebetween; and a fourth spiral conductor provided on the upper surface of the third insulating layer, opposing the second spiral conductor with the third insulating layer interposed therebetween. A conductor layer is provided on the upper surface of the fourth insulating layer, opposing the fourth spiral conductor with the fourth insulating layer interposed therebetween, and is connected to the first coil. This common-mode noise filter can reduce the occurrence of mode conversion.

Description

Technical Field

[0001] The present invention relates to a small and thin common mode noise filter used in various electronic devices such as digital equipment, AV equipment, and information communication terminals. Background Art

[0002] Figure 13 This is an exploded perspective view of a conventional common mode noise filter 500. Common mode noise filter 500 includes coils 2 and 3 formed on multiple stacked insulating layers 1a to 1f. Coil 2 is constructed by connecting spiral coil conductors 4a and 4b, while coil 3 is constructed by connecting spiral coil conductors 5a and 5b. The coil conductors 4a and 4b that constitute coil 2 and the coil conductors 5a and 5b that constitute coil 3 are arranged alternately.

[0003] Patent Document 1 discloses a conventional common mode noise filter similar to common mode noise filter 500 .

[0004] If noise from digital data lines enters a nearby Global Navigation Satellite System (GNSS) antenna, such as the Global Positioning System (GPS), it can degrade reception sensitivity. Unlike other wireless communication functions, GNSS signals are weak signals received from satellites and are therefore susceptible to noise. Therefore, in common-mode noise filters, it is desirable to reduce the mode conversion that converts differential-mode signals (digital signals) input to the common-mode noise filter into common-mode noise within the GNSS frequency band.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-138146 Summary of the Invention

[0008] A common mode noise filter comprises: a laminate comprising a first insulating layer, a second insulating layer, and a second coil provided on the laminate; and a conductor layer provided on the laminate. The first coil comprises a first spiral conductor provided on the lower surface of the first insulating layer; and a second spiral conductor provided on the upper surface of the second insulating layer. The second coil comprises a third spiral conductor provided on the upper surface of the first insulating layer and opposed to the first spiral conductor with the first insulating layer interposed therebetween; and a fourth spiral conductor provided on the upper surface of the third insulating layer and opposed to the second spiral conductor with the third insulating layer interposed therebetween. The conductor layer is provided on the upper surface of the fourth insulating layer and opposed to the fourth spiral conductor with the fourth insulating layer interposed therebetween, and is connected to the first coil.

[0009] The common mode noise filter can reduce the occurrence of mode conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is an exploded perspective view of the common mode noise filter in the first embodiment.

[0011] Figure 2A This is a perspective view of the common mode noise filter in the first embodiment.

[0012] Figure 2B yes Figure 2A This is a cross-sectional view of the common mode noise filter taken along line IIB-IIB.

[0013] Figure 3 This is a circuit diagram of the common mode noise filter in Embodiment 1.

[0014] Figure 4 This is an exploded perspective view of another common mode noise filter in the first embodiment.

[0015] Figure 5 This is a circuit diagram of a common mode noise filter of a comparative example.

[0016] Figure 6 This is an exploded perspective view of yet another common mode noise filter in the first embodiment.

[0017] Figure 7 yes Figure 6 The circuit diagram of the common mode noise filter is shown.

[0018] Figure 8 This is an exploded perspective view of the common mode noise filter in the second embodiment.

[0019] Figure 9 This is a circuit diagram of a common mode noise filter in Embodiment 2.

[0020] Figure 10 This is a diagram showing the frequency characteristics of mode conversion of the common mode noise filters in the first and second embodiments.

[0021] Figure 11 This is an exploded perspective view of another common mode noise filter in the second embodiment.

[0022] Figure 12 yes Figure 11 The circuit diagram of the common mode noise filter is shown.

[0023] Figure 13 This is an exploded perspective view of a conventional common mode noise filter. DETAILED DESCRIPTION

[0024] (Implementation 1)

[0025] Figure 1 This is an exploded perspective view of common mode noise filter 1001 in Embodiment 1. Figure 2A This is a perspective view of common mode noise filter 1001 . Figure 2B yes Figure 2A A cross-sectional view taken along line IIB-IIB of common mode noise filter 1001 is shown. Figure 3 FIG. 1 is a circuit diagram of the common mode noise filter 1001.

[0026] Common mode noise filter 1001 includes: insulating layers 11a to 11f; a spiral conductor 12 formed on insulating layer 11a; a spiral conductor 13 formed on insulating layer 11c; a spiral conductor 15 formed on insulating layer 11b; a spiral conductor 16 formed on insulating layer 11d; and a conductor layer 18a formed on insulating layer 11e. Insulating layers 11a to 11f are stacked in this order, located upward, in stacking direction Du. Insulating layer 11b is provided on the upper surface of insulating layer 11a. Specifically, insulating layer 11a is provided on the lower surface of insulating layer 11b. Insulating layer 11c is provided on the upper surface of insulating layer 11b. Insulating layer 11d is provided on the upper surface of insulating layer 11c. Insulating layer 11e is provided on the upper surface of insulating layer 11d. Insulating layer 11f is provided on the upper surface of insulating layer 11e. The spiral conductors 12 and 13 are connected in series to form a coil 14. The spiral conductors 15 and 16 are connected in series to form a coil 17.

[0027] Spiral conductor 12 is provided on the lower surface of insulator layer 11b. Spiral conductor 15 is provided on the upper surface of insulator layer 11b. Spiral conductor 13 is provided on the upper surface of insulator layer 11c. Spiral conductor 16 is provided on the upper surface of insulator layer 11d. Spiral conductor 15 faces spiral conductor 12 across insulator layer 11b. Spiral conductor 13 faces spiral conductor 15 across insulator layer 11c. Spiral conductor 16 faces spiral conductor 13 across insulator layer 11c.

[0028] One end of conductor layer 18a is connected to coil 14, and the other end is open. Conductor layer 18a is adjacent to and faces spiral conductor 16, the uppermost spiral conductor among spiral conductors 12, 13, 15, and 16, in stacking direction Du. Conductor layer 18a is provided on the upper surface of insulator layer 11e and faces spiral conductor 16 via insulator layer 1ie.

[0029] The insulating layers 11 a to 11 f are made of an insulating non-magnetic material that is not a magnetic body, for example, Cu—Zn ferrite, glass ceramic, or the like, and have a sheet shape.

[0030] The number of insulating layers 11a to 11f is not limited to Figure 1The number of sheets shown. Alternatively, sheet-shaped magnetic layers made of an insulating magnetic material such as Cu-Ni-Zn ferrite may be disposed below the insulating layer 11a and above the insulating layer 11f. Furthermore, the insulating layers 11a to 11f may also be made of a magnetic material such as Cu-Ni-Zn ferrite.

[0031] The insulating layers 11a to 11f stacked in the stacking direction Du constitute a stacked body 19. External electrodes 20a to 20d are provided on the surface of the stacked body 19.

[0032] Coil 14 is disposed inside laminate 19 as one signal line and is composed of spiral conductors 12 and 13. Coil 17 is disposed inside laminate 19 as another signal line and is composed of spiral conductors 15 and 16.

[0033] The spiral conductor 12 and the spiral conductor 13 are connected via a via electrode 21 a , and the spiral conductor 15 and the spiral conductor 16 are connected via a via electrode 21 b .

[0034] The spiral conductors 12 , 13 , 15 , and 16 are formed by plating or printing a conductive material such as silver in a spiral shape.

[0035] Spiral conductor 12 is provided on the upper surface of insulating layer 11a , spiral conductor 13 is provided on the upper surface of insulating layer 11c , spiral conductor 15 is provided on the upper surface of insulating layer 11b , and spiral conductor 16 is provided on the upper surface of insulating layer 11d .

[0036] Specifically, spiral conductors 12 and 13 forming coil 14 and spiral conductors 15 and 16 forming coil 17 are alternately stacked. In the stacking direction Du, spiral conductor 16 is located at the top and spiral conductor 12 is located at the bottom.

[0037] The ends of coil 14 are connected to external electrodes 20a and 20b, respectively. Specifically, one end of spiral conductor 12 is connected to external electrode 20a, and one end of spiral conductor 13 is connected to external electrode 20b. The ends of coil 17 are connected to external electrodes 20c and 20d, respectively. Specifically, one end of spiral conductor 15 is connected to external electrode 20c, and one end of spiral conductor 16 is connected to external electrode 20d.

[0038] Here, in top view, that is, when viewed in the lamination direction Du, the spiral conductors 12 and 15 are partially arranged at substantially the same position and are wound in the same winding direction, thereby being magnetically coupled to each other and forming the common mode filter unit 22 .

[0039] Similarly, in top view, spiral conductors 13 and 16 are partially arranged at approximately the same position and wound in the same winding direction, thereby being magnetically coupled to each other and forming common mode filter section 23. Thus, coils 14 and 17 face each other in the stacking direction Du and are magnetically coupled to each other.

[0040] Conductor layer 18a is located on the upper surface of insulating layer 11e. One end of conductor layer 18a is connected to coil 14, while the other end is open, meaning it is floating and electrically unconnected. Conductor layer 18a is adjacent to and faces spiral conductor 16, located at the top in stacking direction Du.

[0041] That is, in the area between conductor layer 18a and spiral conductor 16, a portion of coil 14 and a portion of coil 17 face each other. As a result, stray capacitance C2a is generated between conductor layer 18a and spiral conductor 16, that is, between coils 14 and 17. Stray capacitance C2a can be adjusted by adjusting the distance between spiral conductor 16 and conductor layer 18a, that is, the thickness of insulating layer 11e.

[0042] One end of the conductor layer 18 a is connected to the external electrode 20 a , and is connected to the spiral conductor 12 of the coil 14 via the external electrode 20 a .

[0043] Figure 1 The illustrated conductor layer 18a is an open coil composed of a spiral conductor. When viewed in the stacking direction Du, the spiral shape of the conductor layer 18a winds in the same direction from the outer circumference to the inner circumference as the spiral shape of the spiral conductor 16. Since the conductor layer 18a, which functions as an open coil and has no current flowing through it, exhibits little magnetic coupling with the spiral conductor 16, it has little effect on the differential signal flowing through the spiral conductor 16, thus minimizing differential signal loss.

[0044] Figure 4 FIG1 is an exploded perspective view of another common mode noise filter 1002 in Embodiment 1. Figure 4 In, with Figure 1 The same reference numerals are used to designate the same parts as those in the common mode noise filter 1001. Figure 4 In the common-mode noise filter 1002 shown, the direction in which conductor layer 18a is wound from the outer periphery is opposite to the direction in which spiral conductor 16 is wound from the outer periphery, as viewed in the stacking direction Du. This structure achieves attenuation characteristics even in differential mode due to magnetic coupling between conductor layer 18a and spiral conductor 16, reducing noise leakage to the surrounding area caused by differential-mode signals.

[0045] Alternatively, conductor layer 18a may be a closed loop (closed coil) with one end connected to the other end, rather than an open coil. Furthermore, conductor layer 18a is not limited to a spiral shape and may also have a plate shape, a mesh shape, or a zigzag shape. However, in the case of a closed loop or a plate-shaped conductor layer 18a, since this may shield the magnetic field and reduce common-mode impedance, an open coil with a spiral shape is more preferable. Furthermore, the number of turns of conductor layer 18a may be the same as or less than the number of turns of spiral conductors 12, 13, 15, and 16.

[0046] In common mode noise filters 1001 and 1002 according to the first embodiment, in addition to stray capacitance C1 generated between spiral conductor 13 of coil 14 and spiral conductor 15 of coil 17 , stray capacitance C2 a also occurs between spiral conductor 16 and conductive layer 18 a .

[0047] Since the conductor layer 18 a is connected to the spiral conductor 12 , a stray capacitance C2 a is generated between the spiral conductors 12 and 16 .

[0048] That is, stray capacitance C1 is generated not only between the spiral conductors 13 and 15 adjacent to each other in the stacking direction Du, but also between the spiral conductors 12 and 16 not adjacent to each other in the stacking direction Du. This maintains the symmetry of the two signal lines, coils 14 and 17, improving the balance of the two signal lines and reducing the possibility of mode conversion.

[0049] Figure 5 This is a circuit diagram of a common mode noise filter of a comparative example. Figure 5 The common mode noise filter shown is Figure 13 The conventional common mode noise filter 500 is shown in FIG. In the common mode noise filter 500, as shown in FIG. Figure 5 As shown, stray capacitance C0 occurs between adjacent coil conductors 4b and 5a in the stacking direction Du, but no stray capacitance occurs between non-adjacent coil conductors 4a and 5b. Consequently, the two signal lines of coils 2 and 3 lose symmetry, degrading their balance and potentially causing mode conversion.

[0050] On the other hand, in common mode noise filter 1001 according to the first embodiment, the possibility of mode conversion occurring can be reduced as described above.

[0051] Figure 6 This is an exploded perspective view of yet another common mode noise filter 1003 in the first embodiment. Figure 7 This is a circuit diagram of the common mode noise filter 1003. Figure 6 and Figure 7 In, with Figures 1 to 4Identical components to those of common mode noise filter 1001 are designated by the same reference numerals. Common mode noise filter 1003 further includes a conductor layer 18b, located below the lowest spiral conductor 12 in the stacking direction Du. This conductor layer 18b has one end connected to coil 17 and the other end open. Common mode noise filter 1003 further includes an insulator layer 11g disposed on the lower surface of insulator layer 11a. Insulator layer 11a is disposed on the upper surface of insulator layer 11g. Conductor layer 18b is disposed on the upper surface of insulator layer 11g.

[0052] The conductor layer 18b is connected to the spiral conductor 16 of the coil 17 via the external electrode 20d. The spiral conductor 12 and the conductor layer 18 are adjacent to and face each other in the stacking direction Du. The conductor layer 18b faces the spiral conductor 12 with the insulating layer 11a interposed therebetween.

[0053] That is, in this portion, part of coil 14 and part of coil 17 also face each other. As a result, stray capacitance C2b is generated between coils 14 and 17. In conductive layer 18a, part of coil 14 and part of coil 17 also face each other, generating stray capacitance C2a between coils 14 and 17. This eliminates directivity in the mounting and characteristics of common mode noise filter 1003.

[0054] Figure 6 Conductor layer 18b, shown as an open coil, is similar to conductor layer 18a and is comprised of a spiral conductor. When viewed in the stacking direction Du, the spiral shape of conductor layer 18b winds in the same direction, from the outer circumference to the inner circumference, as does the spiral shape of spiral conductor 12. Since conductor layer 18b, acting as an open coil and with no current flowing through it, exhibits little magnetic coupling with spiral conductor 12, it has minimal effect on the differential signal flowing through spiral conductor 12, thus minimizing differential signal loss.

[0055] exist Figure 6 The common mode noise filter 1003 shown in FIG. Figure 4 Similarly, in the illustrated common mode noise filter 1002, conductor layer 18a is wound in the opposite direction from the outer periphery of conductor layer 18b, as viewed in the stacking direction Du, to the direction of winding of spiral conductor 12. This structure achieves attenuation characteristics even in differential mode due to magnetic coupling between conductor layer 18b and spiral conductor 12, reducing noise leakage to the surrounding area caused by differential mode signals.

[0056] Figure 4 The common mode noise filter 1003 shown may further include Figure 6The conductor layer 18b of the common mode noise filter 1003 shown in FIG. This arrangement achieves the same effects as common mode noise filter 1003. In this common mode noise filter, the direction in which the conductor layer 18b winds from the periphery is opposite to the direction in which the spiral conductor 12 winds from the periphery, as viewed in the stacking direction Du. This configuration achieves attenuation characteristics even in the differential mode due to the magnetic coupling between the conductor layer 18b and the spiral conductor 12, reducing noise leakage to the surrounding area caused by differential mode signals.

[0057] (Implementation Method 2)

[0058] Figure 8 This is an exploded perspective view of common mode noise filter 1004 in the second embodiment. Figure 9 FIG. 1 is a circuit diagram of the common mode noise filter 1004. Figure 8 and Figure 9 In, with Figures 1 to 4 The same components as those of common mode noise filter 1001 in the first embodiment are denoted by the same reference numerals.

[0059] The common mode noise filter 1004 in the second embodiment is different from the common mode noise filter 1001 in the first embodiment. Figure 8 、 Figure 9 As shown, the spiral conductors 12 and 13 constituting the coil 14 are arranged between the spiral conductors 15 and 16 constituting the coil 17 in the stacking direction Du.

[0060] Spiral conductor 15 is provided on the lower surface of insulator layer 11b. Spiral conductor 12 is provided on the upper surface of insulator layer 11b. Spiral conductor 13 is provided on the upper surface of insulator layer 11c. Spiral conductor 16 is provided on the upper surface of insulator layer 11d. Spiral conductor 12 faces spiral conductor 15 across insulator layer 11b. Spiral conductor 13 faces spiral conductor 12 across insulator layer 11c. Spiral conductor 16 faces spiral conductor 13 across insulator layer 11d.

[0061] One end of the conductor layer 18a is connected to the spiral conductor 15 of the coil 17 via the external electrode 20c, and the other end thereof is open.

[0062] Moreover, similarly to the first embodiment, the spiral conductor 16 is located at the uppermost portion in the stacking direction Du, and is adjacent to and opposed to the conductor layer 18 a in the stacking direction Du.

[0063] According to this configuration, in addition to the stray capacitance C3 generated between the spiral conductors 12 and 13 in the coil 14 , a stray capacitance C4 a is generated between the spiral conductors 16 and 18 a of the coil 17 .

[0064] Since the conductor layer 18 a is connected to the spiral conductor 15 of the coil 17 , a stray capacitance C4 a is generated between the spiral conductors 15 and 16 .

[0065] That is, stray capacitance C4a is generated not only between the spiral conductors 12 and 13 that form coil 14 and are adjacent to each other in the stacking direction Du, but also between the spiral conductors 15 and 16 that form coil 17 and are not adjacent to each other in the stacking direction Du. This maintains the symmetry of the two signal lines of coils 14 and 17, improving the balance of the two signal lines and reducing the possibility of mode conversion.

[0066] Furthermore, since stray capacitance C3 is generated in parallel with spiral conductors 15 and 16, and stray capacitance C4a is generated in parallel with spiral conductors 12 and 13, common mode noise filter 1001 in Embodiment 1 does not generate stray capacitance C1 that couples two signal lines, i.e., coils 14 and 17, to each other, thereby minimizing mode conversion.

[0067] By changing the distance between the conductor layer 18a and the spiral conductor 16, that is, the thickness of the insulating layer 11e, and adjusting the stray capacitance C4a, the frequency f1 that can minimize the mode conversion can be adjusted.

[0068] Figure 10 The frequency characteristics P1004 of the mode conversion from differential mode to common mode of the common mode noise filter 1004 in the second embodiment, the frequency characteristics P1001 of the mode conversion of the common mode noise filter 1001 in the first embodiment, and the frequency characteristics P500 of the mode conversion of the common mode noise filter 500 in the conventional example are shown. Figure 10 In the figure, the horizontal axis represents frequency, and the vertical axis represents the ratio of the magnitude of the component converted into the normal mode in the common mode signal input to common mode noise filters 500, 1001, and 1004 to the magnitude of the common mode signal, i.e., the mode conversion amount, in decibels.

[0069] like Figure 10 As shown, the common mode noise filter 1001 in the first embodiment has a smaller mode conversion than the conventional common mode noise filter 500, making it superior. The common mode noise filter 1004 in the second embodiment has a further reduced mode conversion, making it even better. In the common mode noise filter 1004, the stray capacitance C4a is adjusted by changing the distance between the conductor layer 18a and the spiral conductor 16, that is, the thickness of the insulating layer 11e, thereby adjusting the frequency at which the mode conversion is minimized. For example, Figure 10 At a frequency f1 near the GPS band 1600 MHz, the analog-to-analog conversion amount reaches a minimum value Lmin and is minimized.

[0070] Figure 8The illustrated conductor layer 18a is an open coil composed of a spiral conductor. When viewed in the stacking direction Du, the spiral shape of the conductor layer 18a winds in the same direction from the outer circumference to the inner circumference as the spiral shape of the spiral conductor 16. Since the conductor layer 18a, which functions as an open coil and has no current flowing through it, exhibits little magnetic coupling with the spiral conductor 16, it has minimal effect on the differential signal flowing through the spiral conductor 16, thus minimizing differential signal loss.

[0071] In addition, in the common mode noise filter 1004, Figure 4 Similarly, in common mode noise filter 1002 according to the first embodiment shown, the direction in which conductor layer 18a is wound from the outer periphery is opposite to the direction in which spiral conductor 16 is wound from the outer periphery, as viewed in stacking direction Du. This provides the same effects as common mode noise filter 1002.

[0072] Figure 11 This is an exploded perspective view of another common mode noise filter 1005 in the second embodiment. Figure 12 This is a circuit diagram of the common mode noise filter 1005. Figure 11 and Figure 12 In, with Figure 8 Identical parts to those in the common mode noise filter 1004 are denoted by the same reference numerals. Common mode noise filter 1005 further includes a conductive layer 18b disposed below the lowest spiral conductor 15 in the stacking direction Du. One end of conductive layer 18b is connected to coil 17, and the other end is open.

[0073] The conductor layer 18b is connected to the spiral conductor 16 of the coil 17 via the external electrode 20d. The spiral conductor 15 and the conductor layer 18b are adjacent to and face each other in the stacking direction Du.

[0074] That is, in this portion, spiral conductors 15 and 16, which constitute coil 17 and are adjacent to each other in stacking direction Du, face each other, generating stray capacitance C4b therebetween. In conductor layer 18a, spiral conductors 15 and 16, which also constitute coil 17, face each other, generating stray capacitance C4a therebetween. This eliminates directivity in the mounting and characteristics of common mode noise filter 1005.

[0075] Figure 11The illustrated conductor layer 18b is an open-circuit coil composed of a spiral conductor. When viewed in the stacking direction Du, the spiral shape of the conductor layer 18b winds in the same direction from the outer circumference to the inner circumference as the spiral shape of the spiral conductor 15. Since the conductor layer 18b, which functions as an open-circuit coil and has no current flowing through it, exhibits little magnetic coupling with the spiral conductor 15, it has minimal effect on the differential signal flowing through the spiral conductor 15, thus minimizing differential signal loss.

[0076] In addition, in the common mode noise filter 1005, Figure 4 Similarly, in common mode noise filter 1002 according to the first embodiment shown, the direction in which conductor layer 18a is wound from the periphery is opposite to the direction in which spiral conductor 16 is wound from the periphery when viewed in stacking direction Du. Alternatively, the direction in which conductor layer 18b is wound from the periphery is opposite to the direction in which spiral conductor 15 is wound from the periphery when viewed in stacking direction Du. This achieves the same effects as common mode noise filter 1002.

[0077] In common mode noise filters 1001 to 1005 in Embodiments 1 and 2, the number of coils 14 and 17 and the number of conductor layers 18a are each 1. Common mode noise filters 1001 to 1005 may each be an array-type common mode noise filter having multiple coils 14, multiple coils 17, and multiple conductor layers 18a.

[0078] In the first and second embodiments, terms indicating directions such as "upper surface," "lower surface," and "above" indicate relative directions determined solely by the positional relationship of components of the common mode noise filter, such as the insulating layer and the spiral conductor, and do not indicate absolute directions such as the vertical direction.

[0079] Industrial Availability

[0080] The common mode noise filter disclosed herein has the effect of reducing the possibility of mode conversion and is particularly useful as a small and thin common mode noise filter used as a noise countermeasure for various electronic devices such as digital equipment, AV equipment, and information communication terminals.

[0081] Description of Reference Numerals

[0082] 11a Insulator layer (fifth insulating layer)

[0083] 11b Insulator layer (first insulating layer)

[0084] 11c Insulator layer (second insulating layer)

[0085] 11d Insulator layer (third insulator layer)

[0086] 11e Insulator layer (fourth insulator layer)

[0087] 11f, 11g insulation layer

[0088] 12 Spiral conductor (first spiral conductor)

[0089] 13 Spiral conductor (second spiral conductor)

[0090] 14 Coil (1st coil)

[0091] 15 Spiral conductor (3rd spiral conductor)

[0092] 16 Spiral conductor (4th spiral conductor)

[0093] 17 Coil (2nd coil)

[0094] 18a Conductor layer (first conductor layer)

[0095] 18b Conductor layer (second conductor layer)

Claims

1. A common mode noise filter comprising: a first insulating layer (11b); a second insulating layer (11c) stacked on the upper surface of the first insulating layer (11b); a third insulating layer (11d) stacked on the upper surface of the second insulating layer (11c); a fourth insulating layer (11e) stacked on the upper surface of the third insulating layer (11d); a fifth insulating layer (11a) stacked on the lower surface of the first insulating layer (11b); a first external electrode (20a); a second external electrode (20b); a third external electrode (20c); a fourth external electrode (20d); a first coil (14) comprising a first spiral conductor (12) provided on the lower surface of the first insulating layer (11b) and having one end connected to the first external electrode (20a), and a second spiral conductor (13) provided on the upper surface of the second insulating layer (11c) and having one end connected to the other end of the first spiral conductor (12) and the other end connected to the second external electrode (20b); a second coil (17) comprising a third spiral conductor (15) provided on the upper surface of the first insulating layer (11b) and opposed to the first spiral conductor (12) via the first insulating layer (11b) and having one end connected to the third external electrode (20c); and a fourth spiral conductor (16) provided on the upper surface of the third insulating layer (11d) and opposed to the second spiral conductor (13) via the third insulating layer (11d) and having one end connected to the other end of the third spiral conductor (15) and the other end connected to the fourth external electrode (20d); a first conductor layer (18a) provided on the upper surface of the fourth insulating layer (11e) and opposed to the fourth spiral conductor (16) via the fourth insulating layer (11e), having one end connected to the one end of the first spiral conductor (12) of the first coil (14) and the other end being open; and The second conductor layer (18b) is provided on the lower surface of the fifth insulating layer (11a) and is opposite to the first spiral conductor (12) via the fifth insulating layer (11a), and has one end connected to the second coil (17) and the other end being open. The second spiral conductor (13) is opposed to the third spiral conductor (15) via the second insulating layer (11c), so that a stray capacitance (C1) is generated between the second spiral conductor (13) and the third spiral conductor (15). The first spiral conductor (12) and the third spiral conductor (15) are wound in the same winding direction, thereby being magnetically coupled to each other to form a first common mode filter unit (22). The second spiral conductor (13) and the fourth spiral conductor (16) are wound in the same winding direction, thereby being magnetically coupled to each other to form a second common mode filter unit (23). The winding direction of the first spiral conductor (12) and the third spiral conductor (15) is opposite to the winding direction of the second spiral conductor (13) and the fourth spiral conductor (16).

2. The common mode noise filter according to claim 1, wherein The first conductor layer (18a) is an open-circuit coil.

3. The common mode noise filter according to claim 2, wherein The direction in which the open coil is wound from the outer periphery is the same as the direction in which the fourth spiral conductor (16) is wound from the outer periphery.

4. The common mode noise filter according to claim 2, wherein The direction in which the open coil is wound from the outer periphery is different from the direction in which the fourth spiral conductor (16) is wound from the outer periphery.

5. The common mode noise filter according to claim 1, wherein The one end of the second conductor layer (18b) is connected to the other end of the fourth spiral conductor (16) of the second coil (17).

6. A common mode noise filter comprising: a first insulating layer (11b); a second insulating layer (11c) stacked on the upper surface of the first insulating layer (11b); a third insulating layer (11d) stacked on the upper surface of the second insulating layer (11c); a fourth insulating layer (11e) stacked on the upper surface of the third insulating layer (11d); a first external electrode (20a); a second external electrode (20b); a third external electrode (20c); a fourth external electrode (20d); a first coil (14) having a first spiral conductor (12) provided on the upper surface of the first insulating layer (11b) and having one end connected to the first external electrode (20a), and a second spiral conductor (13) provided on the upper surface of the second insulating layer (11c) and having one end connected to the other end of the first spiral conductor (12) and the other end connected to the second external electrode (20b); a second coil (17) comprising a third spiral conductor (15) provided on the lower surface of the first insulating layer (11b) and opposed to the first spiral conductor (12) via the first insulating layer (11b) and having one end connected to the third external electrode (20c); and a fourth spiral conductor (16) provided on the upper surface of the third insulating layer (11d) and opposed to the second spiral conductor (13) via the third insulating layer (11d) and having one end connected to the other end of the third spiral conductor (15) and the other end connected to the fourth external electrode (20d); and The first conductor layer (18a) is provided on the upper surface of the fourth insulating layer (11e) and is opposite to the fourth spiral conductor (16) via the fourth insulating layer (11e), and has one end connected to the one end of the third spiral conductor (15) of the second coil (17) and the other end is open. The second spiral conductor (13) is opposed to the first spiral conductor (12) via the second insulating layer (11c) so that a stray capacitance (C3) is generated between the first spiral conductor (12) and the second spiral conductor (13). The first spiral conductor (12) and the third spiral conductor (15) are wound in the same winding direction, thereby being magnetically coupled to each other to form a first common mode filter unit (22). The second spiral conductor (13) and the fourth spiral conductor (16) are wound in the same winding direction, thereby being magnetically coupled to each other to form a second common mode filter unit (23). The winding direction of the first spiral conductor (12) and the third spiral conductor (15) is opposite to the winding direction of the second spiral conductor (13) and the fourth spiral conductor (16).

7. The common mode noise filter according to claim 6, wherein The common mode noise filter further comprises: a fifth insulating layer (11a) stacked on the lower surface of the first insulating layer (11b); and The second conductor layer (18b) is provided on the lower surface of the fifth insulating layer (11a) and is opposite to the third spiral conductor (15) via the fifth insulating layer (11a), and has one end connected to the second coil (17) and the other end being open.

8. The common mode noise filter according to claim 7, wherein The one end of the second conductor layer (18b) is connected to the other end of the fourth spiral conductor (16) of the second coil (17).

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