JP2008198863A - Multilayer type common mode choke coil - Google Patents

Abstract

The present invention relates to a multilayer common in which good transmission characteristics can be obtained with little reflection loss even when used in a differential signal transmission line in a microwave region without increasing coil resistance or enlarging the coil size. A mode choke coil is provided.
A first coil A and a second coil B forming a common mode choke coil 20 are each formed by a plurality of conductor layers 30a and 30b stacked with a nonmagnetic dielectric layer 32 interposed therebetween. The conductor layer 30a group that forms the first coil A and the conductor layer 30b group that forms the second coil B are installed separately in the layer direction, and the conductor layer 30a and the second coil B of the first coil A are installed. The capacitor formed between the two conductor layers 30b is distributed along the line direction of the two conductor layers 30a and 30b, so that the signal transmission line and the impedance can be impedance-matched between the first coil A and the second coil B. Form impedance.
[Selection] Figure 2

Description

  The present invention relates to a stacked common mode choke coil in which a pair of coils that are magnetically coupled to each other is formed of a plurality of conductor layers, and is particularly effective for use as a countermeasure against common mode noise in high-speed differential signal transmission.

  For example, in electronic devices such as personal computers and digital AV devices, the speed of signals handled increases as the functions become higher in performance. For this reason, differential transmission systems suitable for high-speed transmission of digital signals have been adopted in these electronic devices.

  Examples of interface standards that use the differential transmission method include USB (Universal Serial Bus), IEEE 1394, LVDS (Low Voltage Differential Signaling), DVI (Digital Video Interface), and HDMI (High-Definition Multimedia Interface).

  These differential transmission systems have the advantage that they are resistant to external noise and have less noise radiation by transmitting signals having opposite phases to each other through a differential transmission line composed of a pair of signal lines. However, in a differential transmission line, common mode (in-phase component) noise may be superimposed between a pair of signal lines. Therefore, it is necessary to distinguish and remove the common mode noise from the differential signal.

  In order to selectively remove common mode noise from the differential transmission path, a common mode choke coil is used. A common mode choke coil is formed by a first coil and a second coil that are magnetically coupled to each other. By inserting these two coils in a differential transmission line, only in-phase signals (in-phase component noise) are selected. Can be offset. In addition, the impedances of the two coils cancel each other out of the differential signals having opposite phases, and the same effect as that in the absence of the coil is generated theoretically.

  As this common mode choke coil, a signal having a pair of coils wound around a magnetic core such as a toroidal core has been used for signal transmission in a relatively low frequency region, but a plurality of conductor layers are used for high-speed digital signal transmission. A laminated common mode choke coil in which coils are laminated to form a coil is generally used.

In this laminated common mode choke coil, as disclosed in, for example, Patent Document 1, a pair of coils that cancel out in-phase signals are connected to each other by connecting a plurality of coil conductor layers laminated via a nonmagnetic insulating layer. It is formed by doing.
JP 2006-173207 A

  However, the present inventors have revealed that the conventional laminated common mode choke coil has the following problems.

  That is, for example, in the laminated common mode choke coil disclosed in Patent Document 1, the conductor layer forming the first coil and the conductor layer forming the second coil are alternately stacked via the insulating layer. However, such a configuration increases the mutual capacitor between the first coil and the second coil.

  When this mutual capacitor is large, the capacitance impedance between the coils is lowered, and the impedance mismatch between the transmission line and the choke coil is enlarged. If there is a mismatched portion (impedance node) having different impedances in the signal transmission path, a transmission loss, so-called reflection loss, occurs due to the signal reflected at the mismatched portion.

  The reflection loss due to this impedance mismatch becomes more apparent as the frequency of the transmission signal becomes higher. For example, in high-speed signal transmission in a high frequency (microwave) region such as 5 GHz, the deterioration of transmission characteristics due to impedance mismatch is a very big problem. Become.

  Impedance mismatching in high-speed signal transmission is a serious problem in addition to an increase in transmission loss due to reflection, as well as signal quality degradation and noise generation caused by interference of the reflected wave with the traveling wave.

  As a workaround for the above problem, for example, it is conceivable to keep the mutual capacitor small by increasing the thickness of the insulating layer between the coil conductor layers. There is a trade off that it is not suitable for density mounting.

  As another method of reducing the mutual capacitor, it is conceivable to narrow the line width of the coil conductor layer. In the laminated coil, the capacitor between the conductor layers can be reduced by reducing the width of the coil conductor layer. However, if the width of the conductor layer is reduced, there arises a problem that the coil resistance increases and the signal transmission loss increases.

  The present invention has been made in view of the above problems, and its purpose is to be used by interposing a differential signal transmission line in the microwave region without increasing the coil resistance or enlarging the coil size. It is still another object of the present invention to provide a laminated common mode choke coil that can obtain good transmission characteristics with little reflection loss.

  Other objects and configurations of the present invention will be clarified in the description of the present specification and the accompanying drawings.

The present invention provides the following solutions.
(1) A laminated common mode choke coil in which a first coil and a second coil forming a common mode choke coil are each formed by a plurality of conductor layers laminated via a nonmagnetic dielectric layer. The conductor layer group that forms the first coil and the conductor layer group that forms the second coil are disposed separately in the layer direction and formed between the conductor layer of the first coil and the conductor layer of the second coil. The multilayer common is characterized in that a characteristic impedance capable of impedance matching with the signal transmission line is formed between the first coil and the second coil by distributing the capacitor to be distributed along the line direction of both conductor layers. Mode choke coil.

  (2) In the above means (1), the conductor layer of the first coil and the conductor layer of the second coil are arranged to have a predetermined width and length, respectively, and the coil pattern of both conductor layers is substantially between the layers. A laminated common mode choke coil characterized by being provided so as to overlap.

  (3) In the above means (1) or (2), the uppermost layer or the lowermost conductor layer of the first coil and the lowermost layer or the uppermost conductor layer of the second coil adjacent thereto are the lines A laminated common mode choke coil having different lengths.

  (4) In any one of the above means (1) to (3), the via that connects the conductor layers of the first coil and the via that connects the conductor layers of the second coil are connected to the center of the common mode choke coil. A laminated common mode choke coil, which is installed on either the left or right side of the surface direction of the magnetic path.

  (5) In any one of the above means (1) to (4), the terminals of the first coil and the second coil are the terminals drawn from the lowermost conductor layer of each coil, and the terminals of each coil. A laminated common mode choke coil, characterized in that terminals drawn from the uppermost conductor layer are provided on the same side.

  (6) In any one of the above means (1) to (5), a nonmagnetic dielectric layer is formed on each of the upper side of the coil pattern located on the uppermost layer and the lower side of the coil pattern located on the lowermost layer. A laminated common mode choke coil.

  (7) The laminated common mode choke coil according to any one of the above means (1) to (6), wherein the nonmagnetic dielectric layer is made of nonmagnetic ferrite.

  (8) A laminated common mode choke coil according to any one of the above means (1) to (7) interposed in a transmission line having a predetermined differential characteristic impedance, the conductor layer of the first coil and the first The total sum of the thicknesses of the nonmagnetic dielectric layer positioned between the conductor layers of the two coils and the nonmagnetic dielectric layer positioned at the portion where the first coil and the second coil are adjacently opposed to each other The characteristic impedance formed between the first coil and the second coil is 0.9 to 1.4 times the thickness of the dielectric layer so as to be the same as the characteristic impedance of the transmission line. A laminated common mode choke coil.

  Multilayer common-mode choke coil with low reflection loss and good transmission characteristics even when used in a differential signal transmission line in the microwave region without increasing coil resistance or increasing coil size Can be provided.

  The operations / effects other than the above will be clarified in the description of the present specification and the accompanying drawings.

FIG. 1 shows an outline of a laminated common mode choke coil 20 according to an embodiment of the present invention. In the same figure, (a) shows the use state of the common mode choke coil 20, (b) shows its external configuration, and (c) shows an equivalent circuit in the use state.
As shown in the figure, a laminated common mode choke coil 20 according to the present invention is used in the middle of a differential transmission path 13 formed on a printed wiring board 10.

The transmission line 13 is formed by a pair of parallel lines 13a and 13b made of strip lines patterned on the surface of the substrate 10. The back surface of the substrate 10 is a full surface conductor (solid conductor) 12 and is connected to the ground potential.
The parallel lines 13a and 13b are opposed to the entire surface conductor 12 via an insulating plate 11 having a predetermined dielectric constant, thereby forming a differential transmission path 13 having a predetermined characteristic impedance (Zo = 100Ω).
One end of the transmission line 13 is connected to a differential signal source (digital signal source) 51 having a predetermined output impedance (Zo = 100Ω). The other end is connected / terminated to a receiving terminal (interface) 52 having a predetermined input impedance (Zo = 100Ω).

  The common mode choke coil 20 is obtained by magnetically coupling the first coil A and the second coil B to each other. The common mode choke coil 20 is interposed in the middle of the transmission line 13 and has a parallel phase between the parallel lines 13a and 13b. While the transmitted differential signal is passed as it is, the in-phase signal (in-phase component noise) is canceled and removed by magnetic induction between the coils A and B.

  The laminated common mode choke coil 20 of the embodiment is formed in a rectangular chip shape for surface mounting. The coils A and B are each formed by coil conductor layers 30a and 30b in the chip.

  The terminals 21a, 22a, 21b, and 22b of the two coils A and B are provided outside the chip, but the input-side terminals 21a and 21b connected to the lines 13a and 13b on the signal source 51 side, The output side terminals 22a and 22b connected to the lines 13a and 13b on the receiving terminal 52 side are installed so as to be located on the same side.

  In the common mode choke coil 20, there is no particular distinction between input and output, and either of the terminals 21a and 21b and 22a and 22b may be on the input side / output side, but here it is positioned on the signal source 51 side for convenience. The terminals 21a and 21b are the input side, and the terminals 22a and 22b positioned on the receiving terminal 52 side are the output side.

  FIG. 2 shows an internal cross-sectional structure of the multilayer common mode choke coil 20 in the stacking direction. In the figure, a first coil A and a second coil B that form a common mode choke coil 20 are each formed by a plurality of coil conductor layers 30a and 30b stacked via a nonmagnetic dielectric layer 32. Yes. Both coils A and B are inductively coupled to each other via a magnetic circuit formed by a magnetic layer 34 laminated together with the dielectric layer 32 and the conductor layers 30a and 30b.

  The conductor layer 30a group that forms the first coil A and the conductor layer 30b group that forms the second coil B are disposed separately in the layer direction. That is, the conductor layer 30a of the first coil A and the conductor layer 30b of the second coil B are not alternately stacked but are divided into a group that forms the first coil A and a group that forms the second coil B. Has been. Each coil conductor layer 30a, 30b is formed using a printed wiring technique.

  Furthermore, as shown in FIG. 3, the conductor layer 30a of the first coil A and the conductor layer 30b of the second coil B are provided so that the pattern widths w are the same and are substantially overlapped in the layer direction. .

  FIG. 3 shows a portion of the overlapping conductor layers 30a and 30b. As shown in the figure, when attention is paid to an arbitrary portion of the conductor layer 30a of the coil A and the conductor layer 30b of the coil B, a portion of the conductor layer 30a (or 30b or 30a and 30b) in addition to the dielectric layer 32 therebetween. Also intervenes. However, since the thickness of the conductor portion can be regarded as equivalently zero, a dielectric having a thickness corresponding to the sum of the thicknesses ST of the dielectric layers 32 interposed between the conductor layers 30a and 30b. It can be seen that the layer 32 is interposed.

  Thereby, capacitors are formed in a distributed state along the line direction of the conductor layer 30a of the coil A and the conductor layer 30b of the coil B. The capacitance value per unit length of the distributed capacitor is the coil conductor layer 30a, It is determined by the width w of 30b, the sum of the thickness ST of the dielectric layer 32, and the dielectric constant (relative dielectric constant εr) of the dielectric layer 32.

  Therefore, if these parameters are set as appropriate, a transmission line having a predetermined characteristic impedance can be formed in the coil conductor layers 30a and 30b. Furthermore, by setting the above parameters so that the characteristic impedance is substantially the same as the characteristic impedance of the transmission line 13 (Zo = 100Ω), the first coil A and the second coil B can generate common mode noise (in-phase component). It is possible to provide a function as a transmission line having a characteristic impedance (Zo = 100Ω) substantially the same as that of the transmission line 13 for differential signals. .

  In this way, a characteristic impedance of 100Ω, which is a standard for high-speed digital signal transmission, can be kept waiting between the first coil A and the second coil B. What should be noted here is that The characteristic impedance value of 100Ω can be achieved without increasing the coil resistance or increasing the coil size.

  This is because the conductor layer 30a group that forms the first coil A and the conductor layer 30b group that forms the second coil B are arranged separately in the layer direction. Since the two conductor layers 30a and 30b are laminated separately for each of the coils A and B, the thickness of the dielectric layer 32 interposed between the conductor layer 30a of the coil A and the conductor layer 30b of the coil B is one dielectric. The total thickness of the plurality of dielectric layers 32 is expanded instead of the thickness ST of the layer 32.

  As a result, the capacitor value between the conductor layer 30a of the coil A and the conductor layer 30b3 of the coil B has a plurality of distances between the capacitor electrodes even if the width w of the conductor layers 30a and 30b, that is, the facing area of the capacitor electrodes is large. By expanding the dielectric layer 32 to the total thickness ST, the dielectric layer 32 can be kept small.

  Even if the width w of the conductor layers 30a and 30b is widened, if the capacitance value formed between them can be made much smaller than before, the characteristic impedance value of, for example, 100Ω can also increase the coil resistance and the coil size. It can be provided between the coils A and B without increasing the size.

  As described above, the laminated common mode choke coil 20 according to the present invention is used by interposing it in the differential signal transmission line 13 in the microwave region without increasing the coil resistance or enlarging the coil size. However, good transmission characteristics can be obtained with little reflection loss.

  FIG. 4 shows an equivalent circuit of a high-speed differential transmission line in which the laminated common mode choke coil 20 of the present invention is interposed. As shown to (a) of the figure, a pair of coils A and B which form the common mode choke coil 20 are interposed in series with a pair of parallel lines 13a and 13b, respectively.

  As shown in FIG. 2B, a predetermined distributed inductor Ls and distributed capacitor Cs are formed in the pair of parallel lines 13a and 13b along the signal transmission direction. A predetermined distributed inductor Lx and distributed capacitor Cx are also formed in the pair of coils A and B along the coil conductor layers 30a and 30b.

  The distributed inductor Ls and the distributed capacitor Cs of the parallel lines 13a and 13b form the same characteristic impedance as the output impedance (Zo = 100Ω) of the signal source 51 and the input impedance (Zo = 100Ω) of the receiving terminal 52. In the coils A and B, a distributed inductor Lx and a distributed capacitor Cx having the same characteristic impedance as the characteristic impedance (Zo = 100Ω) are formed.

  FIG. 6C shows an impedance matching state in which the impedance Zo of the signal source 51 and the receiving terminal 52, the characteristic impedance Zt of the transmission line 13, and the characteristic impedance Zx of the common mode choke coil 20 are identical to each other (Zx = Zo = Zt). The equivalent effective circuit at is shown.

  As in this equivalent effective circuit, in the impedance matching state (Zx = Zo = Zt), the common mode choke coil 20 behaves equivalently to a receiving terminal impedance-matched to the signal source 51, and to the receiving terminal 52. It behaves as if equivalent to the signal source (V), thereby eliminating common mode noise and allowing only the differential signal to be transmitted selectively and efficiently.

  Here, in the laminated common mode choke coil 20 of the present invention described above, the distributed inductor Lx and the distributed capacitor Cx for achieving the impedance matching state (Zx = Zo = Zt) are increased by increasing the coil resistance or the coil size. It is possible to set with a high degree of freedom without any change.

  In this case, it is desirable that the distributed inductor Lx and the distributed capacitor Cx have the same distribution state as much as possible. For this purpose, for example, as shown in FIGS. 2 and 3, both conductor layers of the coils A and B are used. It is effective to make the pattern widths w of 30a and 30b the same, and to provide both conductor layers 30a and 30b so as to substantially overlap in the layer direction.

  Conventionally, when the two conductor layers 30a and 30b are overlapped in the layer direction, there is a concern that the capacitor between the conductor layers 30a and 30b may increase, but in the present invention, the distance between the two conductor layers 30a and 30b (the sum of STs). ) Is equivalently large, so there is no concern.

  FIG. 5 shows a coil conductor layer pattern of the common mode choke coil 20 having the cross-sectional structure shown in FIG. As shown in the figure, the conductor layers 30a and 30b are laminated together with the coils A and B. That is, first, the conductor layers 30a for forming one coil A are sequentially laminated while being connected via the vias 31a. Thereafter, the conductor layer 30b for forming the other coil B is sequentially laminated while being connected via the via 31b.

  In the figure, the conductor layer 30a of the uppermost layer (coil A-2 layer) of the first coil A and the conductor layer 30b of the lowermost layer (coil B-1 layer) of the second coil B adjacent thereto. Are formed with different line lengths. Thereby, it is possible to avoid an unnecessarily large mutual capacitance between the coils A and B.

  In addition, the via 31a that connects the conductor layer 30a of the first coil A and the via 31b that connects the conductor layer 30b of the second coil B are either left or right in the plane direction of the central magnetic path of the common mode choke coil. It is installed in the crab.

  According to this configuration, the conductor layers 30a and 30b of both the coils A and B do not need to be deformed in order to bypass the vias 31a and 31b, and the difference in pattern shape between the coils A and B is reduced. it can. Thereby, the magnetic flux generated by the differential current flowing between the coil A and the coil B can be canceled and the leakage magnetic flux can be reduced. Further, the distribution state of the distributed inductor Lx and the distributed capacitor Cx formed in the coils A and B can be made uniform, and the coils A and B can have better transmission characteristics.

  Furthermore, the terminals 21a, 22a, 21b, and 22b of the first coil A and the second coil B are connected to the terminals 21a and 21b drawn from the lowermost conductor layer of the coils A and B, and to the coils A, respectively. , B are provided such that the terminals 22a, 22b drawn from the uppermost conductor layer are located on the same side.

  As a result, for example, as shown in FIG. 1, it is possible to provide a terminal arrangement that is convenient for interposition with a pair of parallel lines forming a differential transmission line. Moreover, the effect of reducing the difference in the conductor layer pattern shape between the coils A and B can also be obtained.

  The above-described configuration is also suitable for a multilayer common mode choke coil 20 having a multilayer structure in which a coil A and a coil B are formed by three or more conductor layers 30a and 30b, respectively, as shown in FIGS. 6 and 7, for example. It is applicable to.

  The nonmagnetic dielectric layer 32 preferably has a low dielectric loss and a low dielectric constant in the operating frequency range, that is, the transmission frequency range. When the magnetic layer is made of magnetic ferrite and the nonmagnetic dielectric layer is made of nonmagnetic ferrite, the difference in thermal shrinkage between the magnetic ferrite and nonmagnetic ferrite is small. The disconnection failure of the coil pattern can be prevented. As the nonmagnetic ferrite, Zn ferrite can be used.

  FIG. 8, FIG. 9, and FIG. 10 are graphs showing examples of characteristics of the laminated common mode choke coil 20 produced based on the technique of the present invention. FIG. 8 shows changes in the reflection loss (2 GHz) and the cut-off frequency (−3 dB) with respect to the thickness of the nonmagnetic dielectric layer (total ST). FIG. 9 shows changes in reflection loss and transmission efficiency with respect to frequency. FIG. 10 shows changes in normal mode impedance and common mode impedance with respect to frequency.

  Here, in order to suppress the reflection loss shown in FIG. 8 to −20 dB or less, the nonmagnetic dielectric layer 32 located between the conductor layers 30a of the first coil A and between the conductor layers 30b of the second coil B, respectively. And the sum ST (see FIGS. 2, 3 and 6) of the thicknesses of the nonmagnetic dielectric layers positioned at the portions where the first coil A and the second coil B are adjacently opposed to each other. The characteristic impedance formed between A and the second coil B may be in the range of 0.9 to 1.4 times the thickness of the dielectric layer so that the characteristic impedance of the transmission line 13 is the same.

Although the differential characteristic impedance Zdd of the transmission path composed of parallel two flat plates, the relative dielectric constant εr between the parallel two flat plates, the width w and the interval s of the parallel two flat plates, the relational expression as in Expression 1 holds. As shown in FIG. 8, the impedance matching condition (the reflection loss becomes −20 dB or less as shown in FIG. 8 is obtained by increasing the above-mentioned total ST by 0.9 to 1.4 times with respect to the interval s determined by this relational expression. Z matching range) can be obtained.

  FIG. 11 shows a further preferred embodiment of the present invention. In this embodiment, the nonmagnetic dielectric layer 33 is also formed on the upper side of the coil pattern located on the uppermost layer and on the lower side of the coil pattern located on the lowermost layer. That is, it is desirable that the nonmagnetic dielectric layers 32 and 33 be interposed not only between the coil patterns but also between the outermost coil pattern and the magnetic layer 34.

  Thereby, especially in the microwave region of 3 GHz or more, it becomes possible to reduce the transmission loss due to the magnetic material loss and raise the cutoff frequency. In this case, the above-described Zn ferrite is particularly suitable for the nonmagnetic dielectric layers 32 and 33.

  12 and Table 1 are interposed between the relative dielectric constant (εr) of the nonmagnetic dielectrics 32 and 33 and the conductor layer 30a of the coil A in the stacked common mode choke coil 20 having the cross-sectional structure shown in FIG. The thickness ST1 of the nonmagnetic dielectric layer 32 (unit: μm, hereinafter the same), the thickness ST2 of the nonmagnetic dielectric layer 32 positioned between the conductor layer 30a of the coil A and the conductor layer 30b of the coil B, and the coil B The thickness ST3 of the nonmagnetic dielectric layer 32 interposed between the conductor layers 30b and the thickness ST4 of the uppermost layer and the lowermost nonmagnetic dielectric layer 33 are parameters (control factors), and the parameters (εr, ST1, The state of change in the average value of the cutoff frequency (-3 dB) appearing with respect to the change for each of ST2, ST3, ST4) is shown (reference average value = 5.962 GHz).

  As shown in FIG. 12 and Table 1, when the thickness ST4 of the uppermost layer and the lowermost nonmagnetic dielectric layer 33 is changed to 0 μm, 10 μm, and 20 μm, the cutoff frequency changes by about 650 MHz. From this, it can be seen that the nonmagnetic dielectric layer 33 as the uppermost / lower layer has the effect of increasing the cutoff frequency.

  It has also been found that when the thickness ST4 of the uppermost / lower nonmagnetic dielectric layer 33 exceeds 10 μm, the increase in the cut-off frequency becomes moderate, and when it exceeds 30 μm, the increase in the cut-off frequency is hardly affected. Therefore, the thickness ST4 of the uppermost / lower nonmagnetic dielectric layer 33 is preferably 10 μm to 30 μm.

  As described above, the present invention has been described based on the typical embodiments. However, the present invention can have various modes other than those described above.

  Multilayer common-mode choke coil with low reflection loss and good transmission characteristics even when used in a differential signal transmission line in the microwave region without increasing coil resistance or increasing coil size Can be provided.

It is the perspective view and circuit diagram which show the outline | summary of the laminated | stacked common mode choke coil which makes one Embodiment of this invention. It is a figure which shows the internal cross-section in the lamination direction of the lamination type common mode choke coil which concerns on this invention. It is sectional drawing which shows a part of conductor layer in the laminated | stacked common mode choke coil shown in FIG. It is a figure which shows the equivalent circuit of the high-speed differential transmission line in which the lamination type common mode choke coil of this invention was interposed. It is a top view which shows the coil conductor layer pattern of the common mode choke coil which has the cross-sectional structure shown in FIG. It is sectional drawing of the lamination direction which shows the example which formed two coils with the conductor layer of 3 layers, respectively. It is a top view which shows the coil conductor layer pattern of the common mode choke coil which has the cross-sectional structure shown in FIG. It is a graph which shows the change state of the reflection loss (2 GHz) with respect to the thickness (total of ST) of a nonmagnetic dielectric material layer, and a cut-off frequency (-3 dB), respectively. It is a graph which shows the change state of the reflection loss with respect to a frequency, and transmission efficiency, respectively. It is a graph which shows the change state of the normal mode impedance with respect to a frequency, and a common mode impedance, respectively. It is a figure which shows the internal cross-section structure of the laminated | stacked common mode choke coil which formed the nonmagnetic dielectric material layer also on the upper side of the coil pattern located in the uppermost layer, and the lower side of the coil pattern located in the lowest layer. 12 is a graph showing a change state of a cut-off frequency with respect to the thickness of the nonmagnetic dielectric layer in the stacked common mode choke coil shown in FIG.

Explanation of symbols

10 Printed wiring board 11 Insulating plate 12 Full-surface conductor (solid conductor)
13 Transmission path 13a, 13b Parallel line 20 Laminated common mode choke coil 21a, 22a Terminal of coil A 21b, 22b Terminal of coil B 30a30b Conductor layer 31a, 31b Via which makes interlayer connection 32, 33 Nonmagnetic dielectric layer 34 Magnetic Body layer 51 Signal source 52 Receiving terminal A First coil B Second coil

Claims (8)

  Each of the first coil and the second coil forming the common mode choke coil is a stacked common mode choke coil formed by a plurality of conductor layers stacked via a nonmagnetic dielectric layer. The conductor layer group forming the first coil and the conductor layer group forming the second coil are disposed separately in the layer direction, and the capacitor is formed between the conductor layer of the first coil and the conductor layer of the second coil. Is distributed along the line direction of both conductor layers to form a characteristic impedance capable of impedance matching with the signal transmission path between the first coil and the second coil. .   In Claim 1, the conductor layer of the first coil and the conductor layer of the second coil are arranged to have a predetermined width and length, respectively, and the coil patterns of both conductor layers are provided so as to substantially overlap each other. A laminated common mode choke coil.   3. The line length of the uppermost or lowermost conductor layer of the first coil and the lowermost or uppermost conductor layer of the second coil adjacent to the first coil are different from each other. A laminated common mode choke coil, characterized in that   4. The method according to claim 1, wherein the via connecting the interlayer connection of the conductor layer of the first coil and the via connecting the interlayer of the conductor layer of the second coil are arranged in the plane direction of the central magnetic path of the common mode choke coil. A laminated common mode choke coil that is installed on either the left or right side.   5. The terminal according to claim 1, wherein each terminal of the first coil and the second coil is led out from terminals drawn from the lowermost conductor layer of each coil and from the uppermost conductor layer of each coil. A laminated common mode choke coil, wherein the terminals are provided on the same side.   6. The laminated common mode choke according to claim 1, wherein a nonmagnetic dielectric layer is formed on each of an upper side of a coil pattern located on the uppermost layer and a lower side of the coil pattern located on the lowermost layer. coil.   7. The laminated common mode choke coil according to claim 1, wherein the nonmagnetic dielectric layer is made of nonmagnetic ferrite.   The laminated common mode choke coil according to any one of claims 1 to 7, which is interposed in a transmission line having a predetermined differential characteristic impedance, between the conductor layer of the first coil and the conductor layer of the second coil. The sum of the thicknesses of the nonmagnetic dielectric layers positioned in the respective portions and the nonmagnetic dielectric layers positioned in the portions where the first coil and the second coil are adjacently opposed to each other are expressed as follows. A laminated common mode choke characterized in that the characteristic impedance formed between the coils is 0.9 to 1.4 times the thickness of the dielectric layer so that the characteristic impedance of the transmission line is the same. coil.

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