JP6613608B2 - Pulse transformer - Google Patents

Description

  The present invention relates to a pulse transformer used for, for example, an application for transmitting a pulse signal through a LAN cable or the like.

  When connecting a device such as a personal computer to a network such as a LAN or a telephone network, it is necessary to protect the device from ESD (ElectroStatic Discharge) and high voltage entering through a cable. Therefore, a pulse transformer is used as a connector constituting the connection point between the cable and the device.

  A conventional pulse transformer is made by winding a primary coil and a secondary coil around a donut-shaped magnetic core (toroidal core), and only the AC component (pulse) of the voltage applied to the primary coil is secondary. It has the property of transmitting to the coil. Since the direct current component is not transmitted to the secondary coil, the pulse transformer can block ESD and high voltage.

  In recent years, pulse transformers are also required to be miniaturized and surface-mounted. For this reason, an example in which a drum core is used instead of the toroidal core has appeared. Such a pulse transformer is referred to as a surface mount type pulse transformer, and an example thereof is disclosed in Patent Document 1.

  By the way, the network speed of Ethernet (registered trademark) (Ethernet (registered trademark)) from 10BASE-T of 10Mbps (bits per second) to 100BASE-TX of 100Mbps, which is 10 times that, has become widespread. -T is popular. In addition, 10GBASE-T (10 Gigabit Ethernet (registered trademark) (10GbE)) has been newly standardized.

  Therefore, there is a demand for a pulse transformer having a small insertion loss (insertion loss) particularly at a high frequency. If the insertion loss is small, the signal attenuation amount is small, and if the attenuation amount of the high frequency component is small, a high-speed data signal can be accurately sent to a long (long) distance. However, in the conventional pulse transformer, it has been difficult to satisfy the reduction of insertion loss at high frequency with particularly strict standards.

JP 2009-21558 A

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a pulse transformer capable of reducing insertion loss at a high frequency with a particularly strict standard.

  As a result of intensive studies on the pulse transformer, the present inventors have attempted to reduce the insertion loss by overlapping the first assembled layer and the second assembled layer not only over the entire length but only partially. The present inventors have newly found that it is possible to complete the present invention.

That is, the pulse transformer according to the present invention is
A winding core,
A pulse transformer having a primary coil and a secondary coil formed on the outer periphery of the winding core;
The primary coil has a first wire and a second wire,
The secondary coil has a third wire and a fourth wire,
A first assembly layer composed of a combination of the first wire and the third wire and a second assembly layer composed of a combination of the second wire and the fourth wire partially overlap on the outer periphery of the core portion. It has an overlap area.

  In the pulse transformer according to the present invention, the reason why the insertion loss can be reduced in the high frequency region is not necessarily clear, but it is considered that the line capacitance can be reduced by reducing the overlapping region.

  In the pulse transformer of the present invention, since the insertion loss in the high frequency region can be reduced, the amount of signal attenuation at the high frequency is reduced, and a high-speed data signal can be sent accurately over a long (long) distance.

  In the present invention, the first assembly layer includes a first wire that constitutes the primary coil and a third wire that constitutes the secondary coil, and the second assembly layer includes A second wire that will constitute the primary coil and a fourth wire that will constitute the secondary coil are included. For this reason, the primary coil and the secondary coil suppress variations in wire length of the windings, suppress variations in inductance, have excellent balance characteristics, and excellent noise removal characteristics. That is, in the present invention, it is possible to reduce the insertion loss in the high frequency region while maintaining the coupling between the primary coil and the secondary coil.

  Preferably, a winding total length including the first assembly layer and the second assembly layer along the axis of the winding core portion is L1, and the overlap length of the overlap region along the axis is When L2, L2 / L1 is 0.8 or less. If L2 / L1 is too large (that is, the overlap length is long), the effect of reducing the insertion loss tends to be small.

  Preferably, the length of the overlapping region along the axis of the winding core is equal to or greater than a length obtained by adding a wire diameter of the first wire and a wire diameter of the third wire, or a wire of the second wire. It is more than the length which added the diameter and the wire diameter of the said 4th wire. If the length of the overlapping region is too short, the noise reduction effect tends to be small.

  Preferably, L2 / L1 is 0.1 to 0.8, more preferably 0.2 to 0.6. In such a range, the insertion loss can be reduced and the noise reduction effect is also increased.

  The overlapping region may be positioned at a substantially central portion of the entire winding length. With this configuration, the winding work is facilitated. In addition, there may be winding disturbance at the winding start and winding end of each of the first assembled layer and the second assembled layer.

FIG. 1 is a perspective view of a pulse transformer according to an embodiment of the present invention. FIG. 2 is a schematic half-sectional view of a coil portion wound around the core portion of the transformer shown in FIG. FIG. 3 is an equivalent circuit diagram of the transformer shown in FIG. FIG. 4 is a perspective view of a pulse transformer according to another embodiment of the present invention. FIG. 5 is a graph showing the effect of reducing the insertion loss of the pulse transformer according to the embodiment of the present invention.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

First Embodiment As shown in FIG. 1, a pulse transformer according to an embodiment of the present invention is composed of a coil component 10 of a surface mount type. The coil component 10 includes a first core 20 that is a drum-type core, a plate-shaped second core 30, and a coil portion 40 that is wound around the core portion 22 of the first core 20.

  In the description of the coil component 10, the direction parallel to the winding axis of the core portion 22 of the first core 20 in the plane parallel to the mounting surface on which the coil component 10 is mounted is the same as the X axis and the X axis. The direction perpendicular to the X axis in the plane parallel to the Y axis is the Y axis direction, and the normal direction of the mounting surface is the Z axis direction.

  The outer dimensions of the coil component 10 are, for example, (width 3.2 mm × height 2.8 mm × depth 3.2 mm), but the size of the coil component 10 is not limited to this.

  The core of the coil component 10 is configured by combining the first core 20 and the second core 30. The first core 20 includes a rod-shaped core portion 22 and a pair of flange portions 24 and 24 as a pair of core end portions provided at both ends of the core portion 22.

  The outer shape of the flange portion 24 is a substantially rectangular parallelepiped, and the pair of flange portions 24 are arranged so as to be substantially parallel to each other with a predetermined interval in the X-axis direction. The winding core part 22 is connected to the center part of each surface facing each other in the pair of collar parts 24, and connects the pair of collar parts 24. Although the cross-sectional shape of the core part 22 is a rectangle in this embodiment, a circular shape may be sufficient and the cross-sectional shape is not specifically limited.

  The second core 30 is a plate-like core, and the outer shape of the second core 30 is a substantially rectangular parallelepiped whose side in the Z-axis direction is the shortest side. The second core 30 has a substantially rectangular shape that is long in the X-axis direction when viewed from the normal direction (Z-axis direction) of the outer surface 36, but may be a square or other shapes. The upper surface 32 of the second core 30 located at both ends in the X-axis direction faces the bottom surface 24a of the flange 24, and is fixed to the bottom surface 24a with an adhesive such as a thermosetting resin. Thereby, the second core 30 forms a magnetic path continuous with the first core 20.

  Terminal portions 51 to 56 are provided on the flange portions 24 of the first core 20. The terminal portions 51 to 56 are made of metal fittings having a substantially L-shaped outer shape, and at least a part thereof is provided on the installation surface 24 b of the flange portion 24. The installation surface 24b of the flange 24 is an upper surface in the Z-axis direction opposite to the bottom surface 24a facing the upper surface 32 of the second core 30.

  The three terminal portions 51 to 53 are provided on one flange portion 24, and the other three terminal portions 54 to 56 are provided on the other flange portion 24. The interval between the adjacent terminal portions is not equal, and the interval between the terminal portion 52 and the terminal portion 53 is designed to be wider than the interval between the terminal portion 51 and the terminal portion 52, and the interval between the terminal portion 54 and the terminal portion 55. Is designed to be wider than the distance between the terminal portion 55 and the terminal portion 56.

  A coil portion 40 is formed on the core portion 22 of the first core 20. The coil unit 40 is composed of four wires 41 to 44. The wires 41 to 44 are configured by, for example, coated conductors, and have a configuration in which a core material made of a good conductor is covered with an insulating coating film, and are wound around the core portion 22 with a two-layer structure described later. It has been turned.

  As shown in FIG. 2, the second wire 42 and the fourth wire 44 are wound by a normal bifilar around the core 22 to form a second assembly layer 46, and the first wire 41 and the third wire 43 are The first assembly layer 45 is formed by being wound around a normal bifilar around the core portion 22. In the present embodiment, in the substantially central portion in the X-axis direction of the winding core portion 22, a part of the first assembled layer 45 is overlapped and wound on the second assembled layer 46 to overlap and overlap the region 47. However, the reverse is also possible. That is, in the substantially central portion in the X-axis direction of the winding core portion 22, a part of the second assembly layer 46 is overlapped and wound on the first assembly layer 45 to form an overlapping region 47. May be.

  When the overlapping region 47 is formed by overlapping a part of the second assembled layer 46 on the first assembled layer 45 and winding it, the first wire 41 and the third wire for forming the first assembled layer 45 are formed. Bifilar winding with the wire 43 is performed first, and then bifilar winding with the second wire 42 and the fourth wire 44 for forming the second assembled layer 46 may be performed. In the present embodiment, bifilar winding of the second wire 42 and the fourth wire 44 for forming the second assembled layer 46 is performed, and then the first wire 41 for forming the first assembled layer 45 is used. Bifilar winding with the third wire 43 is performed.

  Moreover, in this embodiment, the wires 42 and 44 of the second assembled layer 46 and the wires 41 and 43 of the first assembled layer are wound in opposite directions. Further, the number of windings of the wires 41 to 44 is the same, but may be different.

  In the present embodiment, the entire winding length including the first assembled layer 45 and the second assembled layer 46 along the axis of the winding core portion 22 is L1, and the overlapping length of the overlapping region 47 along the axis. When L2 is L2, L2 / L1 is 0.8 or less. If L2 / L1 is too large (that is, the overlap length is long), the effect of reducing the insertion loss tends to be small.

  The length L2 of the overlapping region 47 along the axis of the winding core portion 22 is equal to or greater than the length obtained by adding the wire diameter of the first wire 41 and the wire diameter of the third wire 43, or the wire diameter of the second wire 42. And the length of the fourth wire 44 plus the wire diameter. That is, the length L2 of the overlapping region 47 is a length of one turn or more of the windings of the first assembled layer 45 or the second assembled layer 46. If the length of the overlapping region L2 is too short, the noise reduction effect tends to be small. In addition, in this embodiment, although the wires 41-44 are all comprised by the wire of the same wire diameter, you may make it differ depending on the case. The wire diameters of the wires 41 to 44 are preferably 0.03 to 0.05 mm.

  Preferably, L2 / L1 is 0.1 to 0.8, more preferably 0.2 to 0.6. In such a range, the insertion loss can be reduced and the noise reduction effect is also increased.

  In the present embodiment, the overlapping region 47 is located at a substantially central portion of the winding total length L1. With this configuration, the winding work is facilitated. Note that each of the first assembled layer 45 and the second assembled layer 46 is an area that is wound around the core 22 in close contact with each other, but each of the first assembled layer 45 and the second assembled layer 46. There may be winding disturbance at the beginning and end of winding.

  In the present embodiment, the four wires 41 to 44 are wound in close contact with each other in the overlapping region 47, and the first wire 41 and the third wire 43 are in close contact with each other in the first assembled layer 45 that is not the overlapping region 47. In the second assembled layer 46 that is not the overlapping region 47, the second wire 42 and the fourth wire 44 are wound in close contact with each other. Even at the boundary between the overlapping region 47 and the non-overlapping region of the second assembly layer 46 located below the overlapping region 47, the second wire 42 and the fourth wire 44 are wound in close contact with each other.

  The first wire 41 and the third wire 43 are wound in close contact with each other even at the boundary between the overlapping region 47 and the non-overlapping region of the first assembled layer 45 located above the overlapping region 47. However, there may be some disturbance in the portion where the wire 41 or 43 of the first set layer 45 located in the upper layer moves to the lower layer (the boundary between the overlapping region 47 and the non-overlapping region). .

As shown in FIG. 2, in the present embodiment, a pair of winding sparse regions 48, in which the wires 41 to 44 are not tightly wound around the flanges 24 on the outer peripheral surface of the winding core portion 22, 49 may be formed. The lengths L3 and L4 of the winding sparse regions 48 and 49 may be the same or different from each other. If the total length of the core part 22 is L0, L3 / L0 or L4 / L0 is not particularly limited as long as it is 0 or more and less than 1.
Ruri.

  As shown in FIG. 1, the wire ends 41a and 41b of the first wire 41 are connected to the terminal portions 54 and 52, respectively, and the wire ends 42a and 42b of the second wire 42 are connected to the terminal portions 51 and 54, respectively. The wire ends 43a and 43b of the third wire 43 are connected to the terminal portions 55 and 53, respectively. Wire ends 44a and 44b of the fourth wire 44 are connected to terminal portions 53 and 56, respectively.

  As shown in FIG. 3, the terminal portions 51 and 52 are used as a positive input terminal IN + and a negative input terminal IN− for balanced input, respectively. The terminal portions 55 and 56 are used as a positive output terminal OUT + and a negative output terminal OUT−, respectively, for balanced output. Terminal portions 53 and 54 are used as intermediate taps CT on the input side and output side, respectively. The wires 41 and 42 constitute a primary winding (primary coil) of the pulse transformer, and the wires 43 and 44 constitute a secondary winding (secondary coil) of the pulse transformer.

  In manufacturing the coil component 10, first, the drum-type first core 20 provided with the terminal portions 51 to 56 and the wires 41 to 44 are prepared. The first core 20 is formed and sintered from, for example, a magnetic material having a relatively high magnetic permeability, such as Ni—Zn ferrite, Mn—Zn ferrite, or metal magnetic material. It is produced by doing. The metal terminal portions 51 to 56 are fixed to the flange portion 24 of the first core 20 by adhesion or the like. In addition, the terminal parts 51-56 may be provided in the collar part 24 by forming a conductor film in the 1st core 20 by printing, plating, etc., and baking the conductor film.

  As the wires 41 to 44, for example, a core material made of a good conductor such as copper (Cu) is covered with an insulating material made of imide-modified polyurethane and the outermost surface is covered with a thin resin film such as polyester. Can do. The first core 20 and the wires 41 to 44 on which the prepared terminal portions 51 to 56 are installed are set in a winding machine, and the wires 41 to 44 are wound around the core portion 22 of the first core 20 in a predetermined order. Turned.

  In the present embodiment, bifilar winding of the second wire 42 and the fourth wire 44 for forming the second assembled layer 46 is performed, and then the first wire 41 for forming the first assembled layer 45 is used. Bifilar winding with the third wire 43 is performed. The wire ends 41a to 44a and 41b to 44b of the wound wires 41 to 44 are fixed to predetermined terminal portions 51 to 55 shown in FIG. 1 by silver brazing, thermocompression bonding, laser bonding, or the like.

  Next, a plate-like second core 30 is prepared and joined to the first core 20 around which the coil portion 40 is wound. Similar to the first core 20, the second core 30 is composed of a sintered or molded body of a magnetic material composed of Ni—Zn-based ferrite, Mn—Zn-based ferrite, metal magnetic material, or the like. .

  In the pulse transformer 10 according to the present embodiment, it is possible to reduce the insertion loss at a high frequency with a particularly strict standard. Although it is not always clear why the insertion loss can be reduced in the high frequency region, the first assembled layer 45 and the second assembled layer 46 are not overlapped over the entire length, but only partially overlap. By doing so, it is considered that the capacity between lines can be reduced.

  In the pulse transformer 10 of the present embodiment, since the insertion loss in the high frequency region can be reduced, the amount of signal attenuation at the high frequency is reduced, and a high-speed data signal can be sent accurately over a long (long) distance.

  In the present embodiment, the first set layer 45 includes a first wire 41 that forms a primary coil and a third wire 43 that forms a secondary coil. Layer 46 includes a second wire 42 that will form the primary coil and a fourth wire 44 that will form the secondary coil. For this reason, the primary coil and the secondary coil suppress variations in wire length of the windings, suppress variations in inductance, have excellent balance characteristics, and excellent noise removal characteristics. That is, in this embodiment, it is possible to reduce the insertion loss in the high frequency region while maintaining the coupling between the primary coil and the secondary coil.

Second Embodiment The coil component 10a as the pulse transformer of the second embodiment shown in FIG. 4 is different in that four terminal portions are provided on the flange portions 24 at both ends, for a total of eight terminal portions. The configuration of is the same as that of the coil component 10 of the first embodiment. The terminal portions 53a and 53b of the coil component 10a correspond to the terminal portion 53 of the coil component 10 of the first embodiment, and the terminal portions 54a and 54b of the coil component 10a correspond to the terminal portion 54 of the coil component 10. ing.

  In the coil component 10a, the electrical connection between the wire end 43b and the wire end 44a and the electrical connection between the wire end 41a and the wire end 42b are performed via a wiring pattern on the wiring board on which the coil component 10a is mounted. Done. Other configurations and operational effects of the coil component 10a according to the present embodiment are the same as in the case of the first embodiment, and a detailed description thereof will be omitted.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, the shape of the first core 20 is not limited to the drum shape shown in the embodiment, and may be an arbitrary shape including a pair of core end portions at both ends of the core portion, such as a U shape. Further, the two flange portions 24 of the first core 20 may have the same shape or different shapes.

  In the above-described embodiment, the first layer 45 of the coil unit 40 is configured by the two wires 41 and 43, and the second layer 46 is configured by the two wires 42 and 44. The one wire 41 and the second wire 42 may be configured by a single wire continuous at the terminal portion 54. Further, the third wire 43 and the fourth wire 44 may be configured by a single wire continuous at the terminal portion 53.

  Furthermore, in the embodiment described above, the terminal portions 53 and 54 are used, but the terminal portions 53 and 54 may be omitted depending on the application. That is, as shown in FIG. 3, the terminal sections 53 and 54 used as the input-side and output-side intermediate taps CT may be deleted to constitute a pulse transformer. In that case, a pulse transformer is formed using only two wires.

  Furthermore, in this embodiment, you may reduce the number of the wires used at the time of winding by devising the winding method of the wire with respect to the winding core part 22. FIG. For example, after forming the first layer (second assembly layer 46 or first assembly layer 45) of the coil portion 40 on the winding core portion 22 using one or two wires, the same wire is used to form the coil portion 40. Form the second layer (first assembly layer 45 or second assembly layer 46), cut the boundary between the primary winding and secondary winding of the coil section, and separate it into primary winding and secondary winding You may do it.

  Furthermore, in the above-described embodiment, in the circuit diagram shown in FIG. 3, the arrangement positions of the first wire 41 and the second wire 42 constituting the primary coil may be reversed. Further, the arrangement positions of the third wire 43 and the fourth wire 44 constituting the secondary coil may be reversed. That is, the first wire and the second wire do not indicate a positional relationship in the primary coil, but mean wires that respectively constitute two arbitrary coils that constitute the primary coil. Similarly, the third wire and the fourth wire do not indicate the positional relationship in the secondary coil, but mean wires that respectively constitute two arbitrary coils that constitute the secondary coil. For this reason, in the circuit shown in FIG. 3, the third wire 43 can be disposed at the position indicated by reference numeral 44 and the fourth wire 44 can be disposed at the position indicated by reference numeral 43. In that case, in FIG. 3, the combination of wires 41 and 44 is the first set layer, and the combination of wires 42 and 43 is the second set layer.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
As shown in FIGS. 1 to 3, a pulse transformer constituted by a coil component 10 in which L2 / L1 is 1/5, L3 / L0 is 1/10, and L4 / L0 is 1/40. Was made. The measurement result of the insertion loss of the pulse transformer is shown by a curve ex1 in FIG. In FIG. 5, the horizontal axis is the measurement frequency (exponential display, the unit is MHz), and the vertical axis is the insertion loss (signal attenuation characteristic / unit is dB). The insertion loss was measured with a network analyzer.

Comparative Example 1
A pulse transformer made of a coil component was produced in the same manner as in Example 1 except that L2 / L1 was 1.0 and the coils 41 were formed by winding the wires 41 to 44 with the same number of turns as in Example 1. The result of measuring the insertion loss (Insertion Loss) of the pulse transformer in the same manner as in Example 1 is shown by a curve Ce1 in FIG.

As shown in FIG. 5, in the pulse transformer (ex1) according to the first embodiment, the insertion loss is reduced in the high frequency band from 1 MHz to 700 MHz as compared with the pulse transformer (Ce1) according to the first comparative example. It was confirmed that In particular, in the high frequency band up to 400 MHz, it was confirmed that the pulse transformer (ex1) according to Example 1 can be set to a reference insertion loss Sdd21 = less than −0.8 dB.

Example 2
A pulse transformer made of a coil component was produced in the same manner as in Example 1 except that L2 / L1 was changed within the range of 0.1 to 0.8. When the insertion loss of the pulse transformer was measured in the same manner as in Example 1, the same result as in Example 1 was obtained.

DESCRIPTION OF SYMBOLS 10 ... Coil component 20 ... 1st core 22 ... Core part 24 ... A collar part (core edge part)
30 ... 2nd core 40 ... Coil part 41 ... 1st wire 42 ... 2nd wire 43 ... 3rd wire 44 ... 4th wire 45 ... 1st assembly layer 46 ... 2nd assembly layer 47 ... Overlapping region

Claims (5)

A winding core,
A pulse transformer having a primary coil and a secondary coil formed on the outer periphery of the winding core;
The primary coil has a first wire and a second wire,
The secondary coil has a third wire and a fourth wire,
A first assembled layer formed by bifilar winding of the first wire and the third wire, and a second assembled layer formed by bifilar winding of the second wire and the fourth wire are formed on the core portion. and overlap region partially overlapped with the outer peripheral, a non-overlapping region not overlapping possess,
In the upper layer of the overlapping region, either the first assembled layer or the second assembled layer is wound,
The pulse transformer in which the first assembly layer or the second assembly layer located in the upper layer is shifted to a lower layer in the non-overlapping region .   The total winding length including the first assembly layer and the second assembly layer along the axis of the winding core portion is L1, and the overlap length of the overlap region along the axis is L2. The pulse transformer according to claim 1, wherein L2 / L1 is 0.8 or less.   The pulse transformer according to claim 2, wherein L2 / L1 is 0.1 to 0.8.   The length of the overlapping region along the axis of the winding core is equal to or greater than the length obtained by adding the wire diameter of the first wire and the wire diameter of the third wire, or the wire diameter of the second wire. The pulse transformer according to claim 1 or 2, wherein the pulse transformer has a length equal to or longer than a length obtained by adding a diameter of the fourth wire. The overlap region, according to claim 2 which is located substantially at the center portion of the winding the entire length including the second set layer and the first set layer along the axis of the winding core portion Pulse transformer.

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