JP2013062477A - Common mode choke coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common mode choke coil that can be used as a noise countermeasure for transmission lines to cope with the acceleration of high-speed signal transmission, achieve reduced floating capacitance between the transmission lines, and realize reduced differential inductance generated in differential current.SOLUTION: In a common mode choke coil, two coils formed with two lines are separately, not alternately, arranged on a nearly I-shaped core such that coil axes become linear. Since the two coils are adjacent only at respective one end turn, floating capacitance becomes small to reduce distortion of transmission signal waveform, and the floating capacitance will not increase in proportion with the increase of the number of windings of the coils. Also, since the coils are wound in directions such that fluxes generated by the differential signal current from the two coils are canceled inside the nearly I-shaped core around which the coils are arranged so that the coil axes become linear, the directions of fluxes generated in the space around the coils are generated in the direction so that the fluxes become canceled, which prevents an increase of distortion in the signal waveform due to the increase of differential inductance.

Description

  The present invention relates to a technology of a common mode choke coil which is an electronic component used for measures against electromagnetic noise.

  In electronic devices and information devices, signals are becoming faster and broadband, and noise countermeasures are becoming difficult and important. These devices are widely used for common mode choke coils as noise countermeasures. Normal single-end drive digital signals are likely to emit noise and are also affected by external noise, whereas differential transmission is a method in which signal waveforms with opposite polarities are transmitted to both lines, With high noise resistance characteristics, high-speed digital devices are becoming widely used for differential signal transmission in typical interfaces such as USB, LAN, and LVDS.

  However, even in this differential signal transmission, if a phase difference or level difference occurs between the signals of both lines in the transmission signal processing circuit or transmission path, common mode noise that causes noise emission occurs. Further, when the impedance balance around the differential signal circuit is lost, it is affected by external noise such as radiation noise.

  Common mode choke coils are often used as countermeasures against such differential transmission noise, but current common mode choke coils have problems in use.

  A typical structure of a common mode choke coil that is commonly used is disclosed in Patent Document 1, for example. This structure is shown in FIG. In this structure, the wires 3 and 6 are alternately arranged and wound around one magnetic core.

  In this type of common mode choke coil, two wire rings 3 and 6 connected to a signal transmission line are alternately wound around the same magnetic core 1, and both wire rings are adjacent to each other. Therefore, many electric lines of force are generated between the 3 and 6 wire rings or between the 3 and 6 wire rings via the core from the wire ring, and there is a large stray capacitance between the wire rings of both lines. Occur. If there is stray capacitance, the waveform of the differential transmission signal to be transmitted is distorted. In particular, when the differential signal used becomes high-speed and the frequency of the transmission signal increases, there is a problem that even if a small stray capacitance is used, the influence becomes large, and the differential signal waveform to be transmitted is greatly distorted, making it unusable for practical use. In a typical conventional common mode choke coil as shown in FIG. 1, when the number of turns of the wire ring is increased, the stray capacitance also increases in proportion to the number of turns. A common mode choke coil with is not available.

  In order to solve such problems, common mode choke coils with a small stray capacitance have been proposed in, for example, Patent Document 2, Patent Document 3, and Patent Document 4.

  Patent Document 2 discloses a common mode choke coil having a structure in which two wire rings are wound around a toroidal core. This structure is shown in FIG. However, this structure has the disadvantages that a wire ring must be wound around the space surrounded by the core, there is no high-speed winding machine, it is not suitable for mass production, and it is difficult to provide electrodes for surface mounting.

  The structure shown in Patent Document 3 is shown in FIG. In this structure, two U-shaped magnetic cores are inserted into two wire rings wound around a bobbin from both sides. In this structure, two wire rings wound around a bobbin are used, and two U-shaped cores are inserted into the wire ring from both sides. For this reason, there exists a fault that a shape becomes large and cost also becomes high.

  As shown in FIG. 4, the structure proposed in Patent Document 4 divides the wire rings of both lines into two cores and separates the distance between the two wire rings to generate floating between the two lines. The capacity is reduced. By constructing two wire rings wound around a pair of electromagnetically symmetrical magnetic cores so that the direction of the winding is reversed, and by combining the two wire rings electromagnetically, The stray capacitance generated between the lines can be reduced.

  However, there is a problem common to any common mode choke coil in which the stray capacitance generated between the rings of both lines shown in FIGS. 2, 3, and 4 is reduced. This is because the magnetic flux generated in the space around the wire ring is generated in the direction in which the magnetic flux is added by the differential current of both wire rings, the differential inductance that affects the differential signal current increases, and the differential signal current is obstructed. It is a problem of giving.

  In a common mode choke coil used for noise suppression in a signal transmission line, if there is a stray capacitance between the lines, the transmission impedance decreases. Further, if there is an inductance generated by a differential current, there is a problem that the transmission impedance becomes high and the transmission waveform is distorted. Therefore, noise suppression components for signal transmission require a common mode choke coil with a small stray capacitance between transmission lines and a small inductance generated by a differential current.

  JP 2002-246244 A   JP 2002-198236 A   JP 2004-214334 A   JP 2010-153684 A

  In an ideal common mode choke coil, as shown in Fig. 5, the magnetic flux generated by the common mode current is added, the common mode inductance is expanded, the magnetic flux generated by the differential current is erased, and the differential inductance is not generated. The differential signal has a function of attenuating common mode noise without being attenuated or distorted.

  Also in the common mode choke coils shown in FIGS. 2, 3, and 4, the magnetic flux generated by the differential current generated in the magnetic core is canceled out, and the differential inductance that affects the differential signal current is generated. do not do. However, in any of the common mode choke coils having the structures shown in FIG. 2, FIG. 3, and FIG. 4, as shown in the example of FIG. 6, the magnetic flux generated in the space around the wire rings is the differential current of both wire wheels. The magnetic flux is generated in the direction in which the magnetic fluxes are added to each other, the differential inductance that affects the differential signal current increases, and the differential signal current is disturbed.

  The speed of signal transmission is increasing, and common mode choke coils used for noise countermeasures on differential transmission lines have a small stray capacitance between both transmission lines and a small amount of differential inductance generated by the differential signal current. A common mode choke coil that does not distort the signal waveform is required. In order to suppress the generation of the differential inductance generated by the differential signal current, a structure capable of suppressing the generation of the differential inductance by eliminating the magnetic flux generated by the differential current not only in the magnetic core but also in the space around the wire ring is required.

  The present invention is capable of taking noise countermeasures on differential signal lines without distorting the waveform even with high-speed signals. The main purpose is to provide a mode choke coil.

  According to the first aspect of the present invention, a pair of loops having the same number of windings arranged in a straight line are wound around a core made of a magnetic material having a pair of electrodes formed at both ends. The wire ring is mainly wound on one side of the core, the other wire ring is mainly wound on the other side of the core, and both ends of the one wire ring are arbitrary 2 formed at the end of the core. Connected to one electrode, both ends of the other ring wire are connected to the remaining two electrodes, and the magnetic flux generated in the core is reversed in one wire ring and the other wire ring when a differential current flows. It is a common mode choke coil wound in the direction. Provided is a common mode choke coil having a small stray capacitance between lines and a small differential inductance generated by a differential signal current. This common mode choke coil has two wire rings wound in the direction in which the magnetic flux generated in the core by the differential current is generated in the opposite direction on the magnetic core so that the winding axis is linear. By arranging the magnetic flux generated by the differential current, not only inside the core, but also in the space around the wire ring, the magnetic flux generated by the two wire rings can create a magnetic flux in the direction of canceling each other, and the differential inductance generated by the differential signal current Can be reduced. And since the location where stray capacitance is generated is almost limited to only one turn at the end where both the rings are adjacent to each other, the stray capacitance between both the rings is small, and the stray capacitance increases by increasing the number of turns. There is nothing.

  The invention of claim 2 is the common mode choke coil according to claim 1, wherein both ends of one wire ring are respectively connected to a pair of electrodes formed at one end portion of the core, and both ends of the other wire ring. Are common mode choke coils each connected to a pair of electrodes formed at the other end of the core.

  The invention of claim 3 is the common mode choke coil according to claim 1, wherein both ends of one wire ring are respectively connected to one of a pair of electrodes formed at one end of the core and the other end of the core. One end of the pair of electrodes formed on one end of the core is connected to one end of the pair of electrodes formed on the other end of the core. A common mode choke coil connected to the remaining electrode. This is an electrode arrangement in which the input / output electrode positions of the wire ring are arranged in the length direction of the magnetic core.

  According to a fourth aspect of the present invention, in the common mode choke coil according to any one of the first to third aspects, the magnetic core has a substantially I-shape in which both ends of the magnetic core are hooked. This is a common mode choke coil. By providing ridges at both ends of the magnetic core, electrode formation is facilitated and mounting properties are reliably improved.

  According to a fifth aspect of the present invention, in the chip common mode choke coil according to any one of the first to fourth aspects of the present invention, the flanges and the flanges at both ends of the magnetic core are magnetically short-circuited by the magnetic bar core. This is a common mode choke coil having a closed magnetic circuit. A differential generated by a differential signal current with a small stray capacitance between two wire rings by magnetically short-circuiting the ridges and ridges at both ends of an I-shaped magnetic core with a magnetic bar core to form a closed magnetic circuit A chip common mode choke coil with low inductance is configured. A common mode choke coil having a small size, a large common mode impedance, a small stray capacitance, and a small differential inductance generated by a differential signal current can be produced.

  A sixth aspect of the present invention is the common mode choke coil according to any one of the first to fifth aspects, wherein the windings of the two wire rings are brought close to each other at the proximal ends of the two separated wire rings. It is a mode choke coil. Provided is a common mode choke coil in which two wire rings are brought close to each other at the close ends of two separate wire rings in order to prevent winding disturbance. If there is a winding disturbance, the common mode impedance will decrease at a high frequency, or if the winding disturbance is large, it will also cause resonance, so by bringing the windings of the two wire rings close together, These problems can be prevented.

  According to a seventh aspect of the present invention, in the common mode choke coil according to any one of the first to sixth aspects, adjacent windings of two wire rings separated at a substantially central portion of the magnetic core are crossed. Provided is a chip common mode choke coil in which some positions of windings are interchanged with each other, and the amount of replacement is adjusted. Even if the common mode choke coil has a little stray capacitance between the two lines or a large differential inductance generated by the differential signal current, it can be matched with the transmission impedance of the input / output circuit of the common mode choke. The differential mode signal can be used for noise suppression without distortion. According to the configuration of claim 7, two adjacent windings of independent wire rings are crossed, the positions of a part of the windings are interchanged with each other, the stray capacitance between the two wire rings and the differential inductance are adjusted, and impedance matching is performed. An adjustable common mode choke can be provided.

  The invention of claim 8 provides an adjustment method for matching impedances of a circuit connected to a common mode choke coil. The invention according to claim 8 is formed by winding a pair of loops having the same number of windings arranged linearly on a core made of a magnetic body having a pair of electrodes formed at both ends. The wire ring is mainly wound on one side of the core, the other wire ring is mainly wound on the other side of the core, and both ends of the one wire ring are arbitrary 2 formed at the end of the core. Connected to one electrode, both ends of the other ring wire are connected to the remaining two electrodes, and the magnetic flux generated in the core is reversed in one wire ring and the other wire ring when a differential current flows. Common mode choke, the windings of the two wire rings are crossed at the approximate center of the magnetic core, and the positions of some of the windings are interchanged with each other. Stray capacitance and differential inductance between two coil rings By adjusting a control method of matching the impedance of the circuit connected to the common mode choke coil.

  In the present invention, a pair of separated windings having the same number of windings are wound linearly on a core made of a magnetic material having a pair of electrodes formed on both ends, respectively. Mainly wound on one side of the core, the other wire ring is mainly wound on the other side of the core, and both ends of one wire ring are connected to any two electrodes formed at the end of the core Both ends of the other ring wire are connected to the remaining two electrodes, and one wire ring and the other wire ring are respectively in directions in which the magnetic flux generated in the core is reversed when a differential current flows. A common mode choke coil that is wound. With such a structure, a common mode choke coil having a small stray capacitance between lines and a small differential inductance generated by a differential signal current can be realized.

  This common mode choke coil has two wire rings wound in the direction in which the magnetic flux generated in the core by the differential current is generated in the opposite direction on the magnetic core so that the winding axis is linear. By arranging the magnetic flux generated by the differential current, not only inside the core, but also in the space around the wire ring, the magnetic flux generated by the two wire rings can create a magnetic flux in the direction of canceling each other, and the differential inductance generated by the differential signal current Can be reduced. And since the location where stray capacitance is generated is almost limited to only one turn at the end where both the rings are adjacent to each other, the stray capacitance between both the rings is small, and the stray capacitance increases by increasing the number of turns. There is nothing. A chip for surface mounting becomes easy.

  It is a figure which shows the structure of the common mode choke coil by which the conventional bifilar winding was generally used, (A) is a front view, (B) is a side view, (C) is a back view.   It is a figure which shows the structural example of the conventional ring type common mode choke coil.   It is a figure which shows the structural example of the common mode choke coil which inserted the magnetic body core in the conventional bobbin.   It is a figure which shows the structural example of the common mode choke coil which combined the symmetrical coil which wound the conventional wire ring in the reverse direction, (A) is a front view, (B) is a side view, (C) is a back view. is there.   It is a figure explaining the principle of a common mode choke coil, and shows the relationship between the electric current in a common mode choke coil, and the magnetic flux in a magnetic body core. (A) shows the common mode current and magnetic flux, and (B) shows the differential current and magnetic flux.   It is a figure which shows the relationship of the magnetic flux of the coil surrounding space in the conventional common mode choke coil, (A) shows a common mode electric current and magnetic flux, (B) shows a differential electric current and magnetic flux.   It is a figure which shows the basic structure of the common mode choke coil by the Example of this invention, (A) is a front view, (B) is a side view, (C) is a back view.   It is a figure which shows the structure of the common mode choke coil by the other Example of this invention, (A) is a front view, (B) is a side view, (C) is a back view.   It is a figure which shows the structure of the common mode choke coil by the other Example of this invention, (A) is a front view, (B) is a side view, (C) is a back view.   It is a figure which shows the structure of the common mode choke coil by the other Example of this invention, (A) is a front view, (B) is a side view, (C) is a back view.   In the split winding common mode choke coil according to the present invention, a differential current and a magnetic flux generated by the differential current are illustrated, (A) is a front view, (B) is a side view, and (C) is a back view. It is.   It is a figure which shows the relationship between the stray capacitance and signal waveform in the common mode choke coil by this invention.   It is a figure which shows the structure of the circuit used for simulation.

  Hereinafter, examples of the present invention will be described with reference to FIGS.

  FIG. 7 shows a basic configuration of the common mode choke coil according to the first embodiment. A pair of electrodes 4 and 5, and 7 and 8 are provided on the flanges at both ends of the core 1 made of a magnetic material such as ferrite. A pair of wires having the same number of windings separated from both ends by connecting the tips of two wires 3 and 6 covered with polyurethane or the like to the electrodes 4 and 7 by a method such as welding, rotating the magnetic core And two wires are drawn from the center to the electrodes 5 and 8 at the other end and connected by welding or the like. In the present embodiment, a pair of wire rings arranged in a straight line of a wire ring 3 having electrodes 4 and 5 and a winding 6 having electrodes 7 and 8 is formed. According to the configuration of the present embodiment, a common mode choke coil having a small stray capacitance between both lines and a small differential inductance generated by the differential signal current can be obtained.

  The configuration of the second embodiment is based on the configuration shown in FIG. A pair of electrodes 4 and 5, and 7 and 8 are provided on the flanges at both ends of the core 1 made of a magnetic material such as ferrite. A pair of wires having the same number of windings separated from both ends by connecting the tips of two wires 3 and 6 covered with polyurethane or the like to the electrodes 4 and 7 by a method such as welding, rotating the magnetic core And two wires are drawn from the center to the electrodes 8 and 5 at the other end and connected by welding or the like. In this embodiment, a pair of wire ring 3 having 4 and 8 electrode arrangements and wire ring 6 having 7 and 8 electrode arrangements are formed. The electrode arrangement may be, for example, a pair of wire rings with 4 and 7 electrode arrangements and wire rings with 5 and 8 electrode arrangements, and the optimum arrangement is selected according to the arrangement of the external circuit. This is a configuration of a common mode choke coil having an electrode arrangement capable of reducing the mounting area during mounting.

  The configuration of the common mode choke coil in the third embodiment is shown in FIG. A pair of electrodes 4 and 5, and 7 and 8 are provided on the flanges at both ends of the core 1 made of a magnetic material such as ferrite. A pair of wires having the same number of windings separated from both ends by connecting the tips of two wires 3 and 6 covered with polyurethane or the like to the electrodes 4 and 7 by a method such as welding, rotating the magnetic core And two wires are drawn from the center to the electrodes 5 and 8 at the other end and connected by welding or the like. A magnetic core 1 made of ferrite or the like is joined to the opposite ends of the magnetic core 1 with a magnetic bar core 2 with an adhesive or the like to magnetically short-circuit to form a closed magnetic circuit. The flanges at both ends of the magnetic core and the magnetic bar core are joined with an adhesive or the like.

  In the present embodiment, a pair of wire rings 3 having 4 and 5 electrode arrangements and wire rings having 7 and 8 electrode arrangements are formed.

  Since the magnetic core 1 made of ferrite or the like has a closed magnetic circuit formed by magnetically short-circuiting the ridges and ridges at both ends with the magnetic bar core 2, the structure is smaller than the structure of the embodiment shown in FIG. A larger common mode impedance can be obtained.

  An operation model of the common mode choke coil in this embodiment is shown in FIG. FIG. 11 is a diagram showing a relationship between two coil positions and a magnetic flux generated by a differential current which is a signal current.

  In the common mode choke coil of the present embodiment, the coils 3 and the coils 6 of the two lines are not alternately arranged, but are arranged so that the winding axis is linearly separated on the magnetic core. The coil 3 and the coil 6 are adjacent to each other at only one turn, the stray capacitance C is small, and the distortion of the differential transmission signal waveform can be suppressed to a small level. Even if the value is increased, the stray capacitance C is not increased proportionally, and the distortion of the signal waveform is not increased.

  As shown in FIG. 11, in this embodiment, a pair of wire rings are arranged on a magnetic core so that the winding axis is linear, and a pair of wire rings can be formed in the core by a differential current. Is wound in the direction that occurs in the opposite direction. Therefore, the magnetic flux generated by the differential signal currents of the two wire rings in the magnetic core is canceled out, and the direction of the magnetic flux generated in the space around the wire ring is also canceled out, which increases the differential inductance. However, the distortion of the signal waveform does not increase. Therefore, the differential inductance generated by the differential signal current can be reduced.

  FIG. 9 shows the configuration of a common mode choke coil according to Example 4 of the present invention. A pair of electrodes 4 and 5, and 7 and 8 are provided on the flanges at both ends of the core 1 made of a magnetic material such as ferrite. A pair of wires having the same number of windings separated from both ends by connecting the tips of two wires 3 and 6 covered with polyurethane or the like to the electrodes 4 and 7 by a method such as welding, rotating the magnetic core , The windings of the two wire rings are brought close to each other at the near end of the substantially central portion of the magnetic core, and the wire from the wire ring 3 connected to the electrode 4 is connected to the electrode 5 and the wire ring connected to the electrode 7 The wire from 6 is pulled out to the electrode 8 and connected by welding or the like. According to this embodiment, a pair of wire rings 3 having electrode arrangements of 4 and 5 and a pair of wire rings having electrode arrangements of 7 and 8 are formed.

  If the winding of the wire ring is disturbed, the common mode impedance may decrease at high frequencies. Moreover, if this disturbance is large, it may cause resonance. The structure of the present embodiment is effective for preventing winding disturbance and loosening, and for improving manufacturing efficiency.

  FIG. 10 shows the configuration of a common mode choke coil according to the fifth embodiment of the present invention. A pair of electrodes 4 and 5, and 7 and 8 are provided on the flanges at both ends of the core 1 made of a magnetic material such as ferrite. A pair of wires having the same number of windings separated from both ends by connecting the tips of two wires 3 and 6 covered with polyurethane or the like to the electrodes 4 and 7 by a method such as welding, rotating the magnetic core The windings 3 and 6 are crossed at the approximate center of the adjacent magnetic core, and the positions of a part of the windings are interchanged with each other. The wire from the wire ring 3 is drawn to the electrode 5 and the wire from the wire ring 6 connected to the electrode 7 is drawn to the electrode 8 and connected by welding or the like. The magnetic core 1 is joined to the flanges 2 at both ends of the magnetic core 1 with an adhesive or the like to magnetically short-circuit to form a closed magnetic circuit. The flanges at both ends of the magnetic core and the magnetic bar core are joined with an adhesive or the like.

  Even if the stray capacitance between the two lines in the common mode choke coil is a little large or the differential inductance generated by the differential signal current is a little large, if it matches the transmission impedance of the input / output circuit of the common mode choke The differential mode signal can also be used for noise suppression without being distorted. In that case, a structure that can finely adjust the stray capacitance between the wire rings and the differential inductance is required. In the embodiment shown in FIG. 10, two wire rings are formed by crossing the wire rings 3 and 6 at the center where two windings are adjacent to each other, exchanging positions of some of the windings with each other, and adjusting the exchanged amount. A common mode choke coil in which the stray capacitance between them and the differential inductance are adjusted can be made.

  The positions of the central portions of the adjacent wire rings 3 and 6 may be replaced with each other not only at one or two places but also at a plurality of places, and may be twisted.

  The configuration of the common mode choke coil according to the sixth embodiment of the present invention is based on FIG. A pair of electrodes 4 and 5, and 7 and 8 are provided on the flanges at both ends of the core 1 made of a magnetic material such as ferrite. A pair of wires having the same number of windings separated from both ends by connecting the tips of two wires 3 and 6 covered with polyurethane or the like to the electrodes 4 and 7 by a method such as welding, rotating the magnetic core The windings 3 and 6 are crossed at the approximate center of the adjacent magnetic core, and the positions of a part of the windings are interchanged with each other. The wire from the wire ring 3 is drawn to the electrode 5 and the wire from the wire ring 6 connected to the electrode 7 is drawn to the electrode 8 and connected by welding or the like. The magnetic core 1 is joined to the flanges 2 at both ends of the magnetic core 1 with an adhesive or the like to magnetically short-circuit to form a closed magnetic circuit. The flanges at both ends of the magnetic core and the magnetic bar core are joined with an adhesive or the like.

  Adjustment of stray capacitance and differential inductance between two wire rings is made by intersecting wire rings 3 and 6 at the central part where two windings are adjacent to each other, exchanging part of the windings with each other, and adjusting the amount of exchange. You can do it. By this adjustment method, the transmission impedance of the input / output circuit of the common mode choke coil can be matched (matched), and the differential mode signal can be taken with no noise distortion without being distorted.

  The place where stray capacitance between the wire rings 3 and 6 is generated is almost limited to only one central turn where both wire rings are adjacent. Many electric lines of force are generated between the wire rings 3 and 6 or between the wire rings 3 and 6 via the core from the wire ring, and stray capacitance is generated between the wire rings of both lines. If the stray capacitance occurs only in the center turn adjacent to it, if the last one turn is completely replaced, the length of the two wire rings adjacent to each other will be tripled, up to about three times the stray capacitance Can be increased and adjusted.

  Using the common mode choke coil produced in Example 6, a simulation was performed to finely adjust the stray capacitance at a transmission speed of 500 MHz, and it was confirmed that the distortion of the signal waveform could be improved as shown in FIG. The simulation was performed with the circuit shown in FIG. For comparison, FIG. 12A shows characteristics of a prototype manufactured in Example 6 having a basic structure. When this stray capacitance is simulated at 1.5 pF close to the matching condition, the waveform distortion is reduced as shown in FIG. Further, when the simulation was performed at 3 pF with a larger stray capacitance, the signal waveform became dull as shown in FIG.

  In the common mode choke coil of this embodiment, even if the stray capacitance between the two lines is a little large or the differential inductance generated by the differential signal current is a little large, it matches the transmission impedance of the input / output circuit of the common mode choke ( If matching is taken, noise countermeasures can be taken without distorting the differential mode signal.

  Digital devices are used in many fields, and differential signal transmissions such as typical interfaces, USB, LAN, and LVDS are widely used for the digital devices, and the speed of differential signal transmission is increasing. As the speed increases, countermeasures against electromagnetic noise are required in the differential signal transmission line, and the common mode choke coil has become an indispensable important component for the countermeasures. However, in the countermeasures against electromagnetic noise of high-speed differential signal transmission, the stray capacitance of the common mode choke coil becomes a problem, and there is no countermeasure component that can take sufficient countermeasures. An inexpensive and effective solution is desired.

  In the present invention, a common mode choke coil having a small stray capacitance can be provided at low cost by linearly separating and separating the wire ring through which the transmission signal passes. A contribution can be expected.

  Moreover, in the electromagnetic noise countermeasure of differential signal transmission, in order to obtain a large noise countermeasure effect, it is necessary to wind a large number of common mode choke coil wires to obtain a large common mode impedance. The conventional common mode choke coil has a problem that when a large number of wire rings are wound, the stray capacitance becomes large and the differential mode differential transmission signal cannot be distorted and a common mode choke coil having a large common mode impedance cannot be obtained. However, according to the present invention, since the number of windings and the stray capacitance are not directly related, a common mode choke coil having a large common mode impedance can be realized, and a large noise countermeasure effect can be obtained. This aspect can also be expected to contribute to the industry.

DESCRIPTION OF SYMBOLS 1 Magnetic body core 2 Magnetic body bar core for forming a closed magnetic circuit 3 Wire ring 4 Electrode 5 Electrode 6 Wire ring 7 Electrode 8 Electrode

Claims (8)

  A core made of a magnetic material having a pair of electrodes formed at both ends is wound with a pair of identically wound wires with the same number of windings, and one wire is mainly a core. The other wire ring is wound mainly on the other side of the core, and both ends of one wire ring are connected to any two electrodes formed on the end of the core, Both ends of the ring wire are connected to the remaining two electrodes, and one wire ring and the other wire ring are respectively wound in a direction in which the magnetic flux generated in the core is reversed when a differential current flows. A common mode choke coil.   Both ends of one wire ring are respectively connected to a pair of electrodes formed at one end of the core, and both ends of the other wire ring are respectively connected to a pair of electrodes formed at the other end of the core. The common mode choke coil according to claim 1, wherein:   Both ends of one wire ring are connected to one of a pair of electrodes formed at one end of the core and one of a pair of electrodes formed at the other end of the core, respectively, and both ends of the other wire ring 2. Each of the electrodes is connected to a remaining electrode of a pair of electrodes formed at one end of the core and a remaining electrode of a pair of electrodes formed at the other end of the core. Common mode choke coil.   The common mode choke coil according to any one of claims 1 to 3, wherein both ends of the magnetic core are generally I-shaped with a hook shape.   5. The common mode choke coil according to claim 1, wherein a closed magnetic circuit is formed by magnetically short-circuiting the flanges at both ends of the magnetic core with a magnetic bar core. 6.   The common mode choke coil according to any one of claims 1 to 5, wherein windings of the two wire rings are brought close to each other at a proximal end of the two separated wire rings.   Cross the adjacent windings of the two wire rings separated at the approximate center of the magnetic core, replace the positions of some of the windings with each other, adjust the amount of replacement, and stray capacitance between the two wire rings The common mode choke coil according to any one of claims 1 to 6, wherein a differential inductance is adjusted.   A pair of wires with the same number of windings arranged in a straight line is wound around a core made of a magnetic material having a pair of electrodes formed at both ends, respectively. Wound on one side of the core, the other wire ring is mainly wound on the other side of the core, both ends of one wire ring are connected to any two electrodes formed on the end of the core, Both ends of the other ring wire are connected to the remaining two electrodes, and one wire ring and the other wire ring are wound in a direction in which the magnetic flux generated in the core is reversed when a differential current flows. The two windings of the common mode choke coil are adjusted by crossing adjacent windings of the two wire rings at approximately the center of the magnetic core, exchanging the positions of a part of the windings with each other, and adjusting the exchanged amount. By adjusting the stray capacitance and differential inductance between Te, adjusting method of matching the impedance of the circuit connected to the common mode choke coil.

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