JP2016092160A - Choke coil, bias t circuit, and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily reduce in size.SOLUTION: A choke coil 100 comprises: a coil pattern 101 that is arranged between input-output terminals, and is wounded in a coil form; and a magnetic band gap 102 that is arranged in an inner space of the coil pattern 101. The magnetic bandgap 102 includes: a land pattern 112 that is formed by connecting a plurality of lands 112a for dividing an area in the inner space with a connection piece 112b; and a meander pattern 122 that is overlapped and arranged to the land pattern 112 so as to be separated in a predetermined interval, and in which a conductor pattern 122a is meandered and formed in an annular shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a choke coil, a bias T circuit including the choke coil, and a communication device.

  In power line communication (PLC), a signal (AC) and a power supply (DC) are superimposed and transmitted, and a communication device including a bias T circuit is used for superimposing and separating these signals and power. For example, by providing a PLC communication device in a car, power can be supplied to the mobile phone terminal simultaneously with the communication between the car and the mobile phone terminal.

  In order to reduce the size of a communication device, it is necessary to reduce the size of a DC cut capacitor used in a bias T circuit and a choke coil that attenuates a high-frequency signal. Metamaterial technology is used for miniaturization of devices. For example, there is an LH transmission line that obtains a large inductance by metamaterial technology, and a filter in which a serial capacitor and a parallel inductor are configured with metamaterial between nodes (for example, see Patent Documents 1 and 2 below). Further, there is an electromagnetic bandgap structure element in which a capacitor having an EBG (Electromagnetic Band Gap) structure is formed on a printed circuit board made of a dielectric and a conductor (see, for example, Patent Documents 3 and 4 below). In addition, there is an electromagnetic bandgap structure element in which a spiral-shaped planar inductance element is formed by an electromagnetic bandgap element (see, for example, Patent Document 5 below).

Special table 2010-507321 gazette JP 2006-222971 A JP 2011-171900 A JP 2010-10183 A International Publication No. 2009/082003

  However, the conventional choke coil requires a space for obtaining a predetermined inductance or capacitance (capacitance) even if the metamaterial technology is used, and further miniaturization cannot be performed. In addition, in order to obtain a wide frequency band for communication in a bias T circuit or a communication device equipped with a choke coil, it is necessary to mount a plurality of choke coils for chip elements on a printed circuit board in a frequency band from a high frequency to a low frequency. Yes, it could not be downsized.

  In one aspect, it is an object of the present invention to be easily miniaturized.

  In one proposal, the choke coil is provided between the input and output terminals, and includes a coil pattern wound in a coil shape, and a magnetic band gap disposed in an internal space of the coil pattern, and the magnetic band gap Is a land pattern formed by connecting a plurality of lands that divide the area of the internal space with connecting pieces, and a meander pattern that is arranged to be overlapped with the land pattern by a predetermined distance and is formed in a ring shape by meandering the conductor pattern It is a requirement that

  According to one embodiment, the size can be easily reduced.

FIG. 1 is a perspective view illustrating a configuration example of a choke coil according to an embodiment. FIG. 2 is a plan view (upper layer) showing a wiring pattern of each layer when the choke coil according to the embodiment is formed using a multilayer printed board. FIG. 3 is a plan view (intermediate layer) showing a wiring pattern of each layer when the choke coil according to the embodiment is formed using a multilayer printed board. FIG. 4 is a plan view (intermediate layer) showing a wiring pattern of each layer when the choke coil according to the embodiment is formed using a multilayer printed board. FIG. 5 is a plan view showing a wiring pattern of each layer when the choke coil according to the embodiment is formed using a multilayer printed board (lower layer). FIG. 6 is a plan view showing the positional relationship of the EBG pattern of the choke coil according to the embodiment. FIG. 7 is a diagram illustrating electrical characteristics between the layers of the choke coil according to the embodiment. FIG. 8 is a diagram illustrating an equivalent circuit of the choke coil according to the embodiment. FIG. 9 is a diagram for explaining the action of the magnetic band gap by the EBG of the choke coil according to the embodiment. FIG. 10 is a diagram for explaining the magnetic action when no EBG is provided. FIG. 11 is a chart illustrating a model example and characteristics of the CRLH according to the embodiment. FIG. 12 is a chart showing frequency characteristics of the choke coil according to the embodiment. FIG. 13 is a chart showing frequency characteristics according to size of the EBG according to the embodiment. FIG. 14 is a side view illustrating a configuration example of a printed board including the choke coil according to the embodiment. FIG. 15 is a table showing frequency characteristics obtained by combining the choke coil and the chip coil according to the embodiment. FIG. 16 is a perspective view illustrating a configuration example of a choke coil according to another embodiment. FIG. 17A is a plan view showing a wiring pattern of each layer when a choke coil according to another embodiment is formed using a multilayer printed board (part 1). FIG. 17B is a plan view showing a wiring pattern of each layer when the choke coil according to another embodiment is formed using a multilayer printed board (part 2). FIG. 18 is a circuit diagram illustrating a bias T circuit including the choke coil according to the embodiment. FIG. 19 is a circuit diagram illustrating a configuration example of a communication device including a bias T circuit having a choke coil according to an embodiment. FIG. 20 is a diagram illustrating a communication device having the choke coil according to the embodiment.

(Embodiment)
Hereinafter, preferred embodiments of the disclosed technology will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view illustrating a configuration example of a choke coil according to an embodiment. In the figure, X is the length direction, Y is the width direction, and Z is the height direction.

  As shown in FIG. 1A, the choke coil 100 is arranged in a coil pattern 101 in which a coil is wound between one end and the other end, which are input / output terminals, and an internal space of the coil pattern 101. And a magnetic band gap (EBG pattern) 102. The coil pattern 101 is configured to be wound in a rectangular shape with the length direction X as an axis in the illustrated example, but may be a circular shape or a polygonal shape and have a predetermined diameter (inner diameter). One end 101A of the coil pattern 101 is an input terminal of the choke coil 100, and the other end 101B is an output terminal.

  The coil pattern 101 is configured by connecting an upper coil pattern 101a, a lower coil pattern 101b, and a pair of side coil patterns 101c and 101d. A part of the connection configuration will be described. One end 101aa of the upper coil pattern 101a is connected to one end 101ba of the lower coil pattern 101b through the side coil pattern 101c. The other end portion 101ab of the upper coil pattern 101a is connected to the other end portion 101bb of the lower coil pattern 101b via the side coil pattern 101d.

  The upper coil pattern 101a, the side coil pattern 101c, the lower coil pattern 101b, the side coil pattern 101d, and the connection to the upper coil pattern 101a are repeated, so that one coil-shaped coil pattern having a predetermined length is obtained. 101 is formed. Note that the coil pattern 101 can also be configured by winding a single conductor in a coil shape.

  The EBG 102 is disposed inside the coil pattern 101 and is disposed so as not to be in electrical contact with the coil pattern 101. In the example of FIG. 1, the EBG 102 is an example in which two pairs of land patterns 112 and meander patterns 122 separated by a predetermined distance are arranged above and below the internal space of the coil pattern 101, but at least one set may be arranged. . The EBG 102 itself is not directly grounded or the like.

  FIG. 1B shows a set of land patterns 112 and meander patterns 122 in the EBG 102. The EBG 102 (land pattern 112 and meander pattern 122) has a length equivalent to the coil pattern 101 in the length direction X.

  The land pattern 112 is formed by connecting a plurality of rectangular lands 112a and four sides of the adjacent lands 112a to each other by connection pieces 112b. The meander pattern 122 is formed in an annular shape (ring shape) by meandering the conductor pattern 122a.

  The coil pattern 101 and the EBG 102 are made of a material such as a conductive metal. A base material having a predetermined dielectric constant is provided between the coil pattern 101 and the EBG 102. As the substrate, a printed board such as a glass epoxy resin having a predetermined dielectric constant, Teflon (registered trademark), or the like can be used, and the substrate may be formed by a method of filling the substrate. In addition, most of the region where the substrate is provided can be an air layer (in this case, a fixing member for holding the EBG 102 is provided in a part of the coil pattern 101).

  2-5 is a top view which shows the wiring pattern of each layer at the time of forming the choke coil concerning Embodiment using a multilayer printed circuit board. A configuration example in which the coil pattern 101 and the EBG 102 are formed using a multilayer printed circuit board (PCB) will be described. The choke coil 100 can be formed by forming predetermined conductor patterns on each of the six layers of the multilayer printed board. 3 to 5 do not describe the printed circuit board itself.

  For example, a glass epoxy (FR4) material is used for the printed circuit board. The first layer 301 to the sixth layer 306 are separated by a thickness corresponding to each layer, and each conductor pattern formed on each layer is separated with a predetermined interval corresponding to the layer.

  FIG. 2 is a diagram showing the first layer (upper layer) 301 of the printed circuit board, and the conductor pattern of the upper coil pattern 101a shown in FIG. 1 is formed. As shown in the drawing, the upper coil pattern 101a is composed of a plurality of conductor patterns inclined at a predetermined angle in the length direction X. The entire length of the upper coil pattern 101a is La and the width is W1.

  FIG. 3 is a diagram illustrating the second layer 302 and the fifth layer 305 (first intermediate layer) of the printed circuit board. In both the second layer 302 and the fifth layer 305, the land pattern 112 of the EBG 102 shown in FIG. 1 is formed by a conductor pattern.

  The size W2 in the width direction Y of the land pattern 112 is smaller than the width W1 of the upper coil pattern 101a. The plurality of rectangular lands 112a have a length (and width) of W3, and are connected with a width W4 by a connecting piece 112b. The land pattern 112 is not a land that is uniformly (solid) formed on the entire surface of the internal space of the printed circuit board. The land pattern 112 includes a rectangular land 112a obtained by dividing a surface (area) of the internal space of the coil pattern 101 into a plurality of predetermined sizes, and a connection piece 112b (inductor) that connects capacitances of the land 112a.

  FIG. 4 is a diagram showing a third layer 303 and a fourth layer 304 (second intermediate layer) of the printed circuit board, and each of the third layer 303 and the fourth layer 304 includes the EBG 102 shown in FIG. The meander pattern 122 is formed. 4A shows the meander pattern 122 of the third layer 303, and FIG. 4B shows the meander pattern 122 of the fourth layer 304. As shown in the figure, the meander pattern 122 of the third layer 303 and the meander pattern 122 of the fourth layer 304 have shapes that are vertically inverted with the length direction X as an axis.

  The size W2 of the meander pattern 122 in the width direction Y is smaller than the width W1 of the upper coil pattern 101a (same as W2 of the land pattern 112). As shown in the figure, the meander pattern 122 has a predetermined inductance L by meandering the conductor pattern 122a to form an annular shape.

  FIG. 5 is a diagram showing a sixth layer (lower layer) 306 of the printed circuit board. In this sixth layer 306, a conductor pattern of the lower coil pattern 101b shown in FIG. 1 is formed. As shown in the figure, the lower coil pattern 101b is composed of a plurality of conductor patterns inclined at a predetermined angle in the length direction X. The inclination direction of the lower coil pattern 101b is opposite to the inclination direction of the upper coil pattern 101a. The dimensions of each part of the lower coil pattern 101b are the same as those of the upper coil pattern 101a, and the overall length is La and the width is W1.

  The one end 101aa of the upper coil pattern 101a of the first layer 301 is connected to the one end 101ba of the lower coil pattern 101b of the sixth layer 306 via the side coil pattern 101c described in FIG. The side coil pattern 101 c is formed by a through hole (via) provided between the first layer 301 and the sixth layer 306. Similarly, the other end 101ab of the upper coil pattern 101a of the first layer 301 is connected to the other end 101bb of the lower coil pattern 101b of the sixth layer 306 through the side coil pattern 101d. The side coil pattern 101d is also formed by vias provided between the first layer 301 and the sixth layer 306.

  The inclination direction of the lower coil pattern 101b is opposite to the inclination direction of the upper coil pattern 101a. Then, the upper coil pattern 101a and the lower coil pattern 101b on the same position in a plan view are electrically connected between the layers via vias of a multilayer printed board. As a result, the coil pattern 101 having a predetermined length wound in the coil shape shown in FIG. 1 and the like can be formed on the multilayer printed board.

  A dimension example of each part of the choke coil 100 will be described. The overall dimensions of the choke coil 100 are a width W1 = 1.7 mm, a length La = 2.2 mm, and a thickness d = 0.4 mm. The width La1 of the conductor pattern on the upper coil pattern 101a and the lower coil pattern 101b is 0.1 mm, the interval La2 is 0.1 mm, and the total length (coil length) of the wound coil pattern 101 is 25 mm. Thus, in the embodiment, a coil length of 25 mm can be obtained by using a region on the printed board having a length La = 2.2 mm and a width W1 = 1.7 mm.

  The land pattern 112 of the EBG 102 has a width W2 = 1.1 mm, a size (length and width) W3 = 0.5 mm of the land 112a, and a length (interval of the land 112a) W4 = 0.1 mm of the connection piece 112b. It is. The length La is the same as the upper coil pattern 101a and the lower coil pattern 101b.

  Further, the meander pattern 122 of the EBG 102 has a width W2 = 1.1 mm, a width W5 = 0.5 mm per turn, an outer diameter La2 = 0.3 mm in length, and gaps La3, W6 = 0.1 mm in turn. is there. The length La is the same as the upper coil pattern 101a and the lower coil pattern 101b.

  The printed circuit board characteristics are: 10-layer board, board thickness d = 0.4 mm (see FIG. 7), dielectric constant = 3.95, Tan δ = 0.012, conductor pattern material = Cu 5.8e7 s / m, conductor The thickness is 0.018 mm, and the via diameter is 0.06 mm.

  The width La1 of the coil pattern 101 is determined by the capacitance immediately below the coil pattern 101 (capacity of the land pattern 112 of the EBG 102), and the inductance L is determined by the total length of the coil pattern 101, thereby forming a closed circuit of the LC resonator. For this reason, the frequency characteristic of a high frequency can be adjusted by changing the pattern width or total length of the coil pattern 101 surrounding the EBG 102.

  FIG. 6 is a plan view showing the positional relationship of the EBG pattern of the choke coil according to the embodiment. The state where the meander pattern 122 of the third layer 303 is superimposed on the land pattern 112 of the second layer 302 is shown. The land pattern 112 has a capacity by forming a plurality of lands 112a as large as possible with a predetermined size (width and length W3), and the adjacent lands 112a are connected by connection pieces 112b (inductance components). Thus, a left-handed right-handed circuit that connects the left-handed circuit and the right-handed circuit is formed.

  In contrast to the land pattern 112 of the second layer 302, the meander pattern 122 of the third layer 303 is formed such that the conductor pattern 122a meanders a plurality of times at the positions of the plurality of lands 112a, and is as long as possible. The inductor component is increased by ensuring a longer period. The meander pattern 122 of the fourth layer 304 and the land pattern 112 of the fifth layer 305 have the same positional relationship as in FIG.

  FIG. 7 is a diagram illustrating electrical characteristics between the layers of the choke coil according to the embodiment. The first layer 301 and the sixth layer 306 have coil patterns 101a and 101b of the choke coil 100 and have an inductance L. Specifically, the coil patterns 101a and 101b have inductances L due to a plurality of conductor patterns in the length direction X, respectively.

  Further, regarding the EBGs 102 of the second layer 302 to the fifth layer 305, the land pattern 112 of the second layer 302 and the fifth layer 305 has a capacitance C2 and an inductor L2 due to the land 112a, and an inductance L1 due to the connection piece 112b. The meander pattern 122 of the third layer 303 and the fourth layer 304 has an inductance L3 and a capacitance C3 due to the plurality of conductor patterns 122a in the length direction X.

  Each of the first layer 301 to the sixth layer 306 has predetermined capacitances (capacitances) C1-2, C2-3,..., C5-6 that the multilayer printed board has. Between the first layer 301 and the second layer 302 is a capacitance C1-2, and between the fifth layer 305 and the sixth layer 306 is a capacitance C5-6.

  FIG. 8 is a diagram illustrating an equivalent circuit of the choke coil according to the embodiment. An equivalent circuit of the EBG 102 is connected in parallel with the inductance L of the upper coil pattern 101a and the lower coil pattern 101b between the first layer 301 of the input terminal 101A of the choke coil and the sixth layer 306 of the output terminal 101B. .

  The equivalent circuit of the EBG 102 includes a capacitance C1-2 of the printed circuit board between the first layer 301 and the second layer 302 and a connection piece 112b of the land pattern 112 of the second layer 302 between the input terminal 101A and the output terminal 101B. The inductance L1 is directly connected. Further, the parallel circuit 801 of the capacitance C2 of the land pattern 112 of the second layer 302 and the inductance L2 is directly connected. Further, the parallel circuit 802 of the capacitance C2 of the land pattern 112 of the fifth layer 305 and the inductance L2 is directly connected. Further, the capacitance C5-6 of the printed circuit board between the fifth layer 305 and the sixth layer 306 is directly connected to the inductance L1 of the connection piece 112b of the land pattern 112 of the fifth layer 305.

  Further, between the inductance L1 and the parallel circuit 801, a parallel circuit 803 of the inductance L3 and the capacitor C3 by the meander pattern 122 of the third layer 303 is connected. Further, between the inductance L1 and the parallel circuit 802, a parallel circuit 804 of the inductance L3 and the capacitor C3 by the meander pattern 122 of the fourth layer 304 is connected. The parallel circuits 803 and 804 are grounded at a high frequency.

  By forming conductor patterns of the coil patterns 101a and 101b of the first layer 301 and the sixth layer 306 in the above dimension example and via-connecting these layers, the choke coil 100 wound in a coil shape is formed. The Further, the EBG 102 is formed using the second layer 302 to the fifth layer 305 that are intermediate layers between the first layer (upper layer) 301 and the sixth layer (lower layer) 306. The principle of the right-handed left-handed medium (CRLH) is realized using the EBG 102. The EBG 102 functions as a magnetic band gap with respect to the upper coil pattern 101a and the lower coil pattern 101b.

  FIG. 9 is a diagram for explaining the action of the magnetic band gap by the EBG of the choke coil according to the embodiment. The distance between the upper coil pattern 101a of the first layer 301 and the lower coil pattern 101b of the sixth layer 306 is about a thin substrate thickness d (0.4 mm, see FIG. 7). In the choke coil of the embodiment, since the printed board is thin, the upper coil pattern 101a and the lower coil pattern 101b are arranged close to each other.

  Here, in the embodiment, the EBG 102 (land pattern 112 and meander pattern 122) is provided between the upper coil pattern 101a of the first layer 301 and the lower coil pattern 101b of the sixth layer 306. By forming a capacitance with the land pattern 112 of the second layer 302 and the fifth layer 305 and forming an inductance with the meander pattern 122 of the third layer 303 and the fourth layer 304, the resonance frequency is determined and becomes a magnetic wall. Due to this magnetic wall, as indicated by arrows in the figure, the magnetic fluxes of the upper coil pattern 101a and the lower coil pattern 101b flow along the EBG 102. Thereby, a magnetic field can be generated in the coil pattern 101, and a current can be passed through the coil pattern 101.

  The EBG 102 has the same effect as a magnetic material such as ferrite, and is easier to process than ferrite and can be formed on a printed circuit board with a general-purpose pattern, so that it can be formed easily and inexpensively.

  FIG. 10 is a diagram for explaining the magnetic action when no EBG is provided. FIG. 10 is different from FIG. 9 in that the EBG 102 is not provided. Thus, when the coil pattern 101 is formed with a thin printed circuit board and the EBG 102 is not provided, the magnetic flux of the upper coil pattern 101a and the magnetic flux of the lower coil pattern 101b collide and cancel each other, so that a current flows through the coil pattern 101. Not flowing.

  As described above, in the embodiment, when the upper coil pattern 101a of the first layer 301 and the lower coil pattern 101b of the sixth layer 306 are close to each other using a printed board or the like, the EBG 102 is provided to cancel the magnetic fluxes. The phenomenon is blocked.

  The resonance frequency of the choke coil 100 can be controlled by changing the constants of the inductance L and the capacitance C of the EBG 102. Since the EBG 102 has a magnetic band gap, the magnetic flux of the upper coil pattern 101a and the magnetic flux of the lower coil pattern 101b are separated. As a result, even when the coil pattern 101 is formed with a conductor pattern on a thin printed board, the effect of canceling out magnetic fluxes from above and below can be attenuated, and the effect that the amount of inductance of the coil pattern 101 does not change can be obtained.

  As described above, the EBG 102 has one set for the second layer 302 and the third layer 303, which are intermediate layers of the printed circuit board, and another set for the fourth layer 304 and the fifth layer 305 in accordance with the CRLH principle. It can be formed simply by forming a conductor pattern. Then, the EBG 102 is provided in the intermediate layer (second layer 302 to fifth layer 305) of the coil-shaped choke coil 100 using the first layer 301 and the sixth layer 306 (upper and lower layers) and vias, whereby the choke coil 100 is provided. The transmission / reception sensitivity can be improved while downsizing.

  Here, as described above, by forming the EBG 102 in two layers and one set in a total of four layers and two sets, the capacitance C can be increased and the choke coil 100 can be reduced in size. At least one set of EBGs 102 may be provided in an intermediate layer positioned between the upper layer and the lower layer on which the coil pattern 101 of the multilayer printed board is formed. For example, the EBG 102 may be formed only in one set of two layers (second layer 302 and third layer 303). In this case, a four-layer printed board is used, and the first layer 301 (upper layer) and fourth layer are used. The coil pattern 101 is formed using 304 (lower layer), and an EBG 102 (land pattern 112 on the second layer 302 and meander on the third layer 303 is formed on the intermediate layer located between the first layer 301 and the fourth layer 304. A pattern 122) may be formed.

  As shown in FIGS. 3 and 4, the EBG 102 forms the land pattern 112 and the meander pattern 122 by the conductor pattern 122a on the printed circuit board. Therefore, the land pattern 112 increases the capacitance (parasitic capacitance), and the meander pattern In 122, the inductance component can be increased.

  When a magnetic field component perpendicular to the surface of the EBG 102 composed of the land pattern 112 and the meander pattern 122 is incident, a repulsive magnetic field that cancels the incident magnetic field is created on the conductor pattern of the EBG 102, and the induced current is induced according to the principle of electromagnetic induction, The EBG 102 becomes a magnetic wall and the current is cut off. Then, charges are accumulated by the land pattern 112 of the EBG 102, and this capacitance becomes a current in the reverse direction, thereby forming a closed circuit of the LC resonator. The resonance frequency f0 of the choke coil 100 is determined by the following equation (1) based on the inductance L and the capacitance C of the coil pattern 101 and the EBG 102. f0 is set to a desired frequency.

  f0 = 1 / 2π√CL (1)

  Due to the reverse induced current of the EBG 102, the magnetic permeability μ changes in the repulsive magnetic field, and the incident electromagnetic wave of the EBG 102 resonates with the EBG 102 and is absorbed. The absorbed action is an effect of changing the magnetic permeability μ. Therefore, the magnetic field absorption effect has an effect of making the permeability μ negative, which satisfies the fact that the refractive index n, which is a metamaterial definition, becomes negative, and the EBG 102 has a metamaterial structure.

Relational expression of EBG102 Dielectric constant ε and permeability μ Permittivity ε = n / z, permeability μ = nz
About refractive index n and impedance z

S ₁₁ is reflection coefficient when metamaterial (EBG102) is irradiated with plane wave, and S ₂₁ is transmission coefficient

  For constants k and d, k = 2πf / C, d = substrate width of EBG102

  FIG. 11 is a chart illustrating a model example and characteristics of the CRLH according to the embodiment. The CRLH line is represented by a unit element model in which a series capacitance and series inductance circuit of an ideal left-handed line and a parallel inductance and a parallel capacitance are inserted. In CRLH, the length Δz of the circuit section is handled as a section of unit elements having a lattice constant a.

  In the dispersion characteristics, ω is an angular frequency, and β is a phase constant (wave number). The CRLH line is a line having Δz as a periodic structure with a finite ground and having a periodicity of a propagation wave, having a left-handed transmission band on the low frequency side and a right-handed transmission band on the high frequency side. The characteristics of the CRLH line change depending on the frequency, and have the characteristics of a high-pass cutoff, a left-handed propagation band, a band gap, a right-handed propagation band, and a low-pass cutoff in order from the low frequency side to the high frequency side. The low-pass cutoff and the high-pass cutoff are caused by a finite number of unit elements. The cutoff wave number of a one-dimensional CRLH line having a periodic structure is π / a, which corresponds to a Bragg reflection condition.

For the phase velocity (v _p ), group velocity (v _g ), and characteristic impedance, a homogeneous medium approximation is established when the absolute value of β is small, and an effective dielectric constant and permeability can be defined, but the absolute value of β When is large, the wave is treated as a periodic structure because the effect as a Bloch wave increases. In the case of this periodic structure, the characteristic impedance of the line is not uniquely determined, but the impedance Z _B for the Bloch wave in the periodic structure is calculated as shown. Z _L = (L _L / C _L ) ^1/2

  FIG. 12 is a chart showing frequency characteristics of the choke coil according to the embodiment. The horizontal axis is frequency, and the vertical axis is attenuation. As shown in the figure, according to the above dimension example (the width La1 of the coil pattern 101 = 0.1 mm), the choke coil 100 having the resonance frequency f0 in the vicinity of 1.9 GHz can be obtained.

  FIG. 13 is a chart showing frequency characteristics according to size of the EBG according to the embodiment. The horizontal axis is frequency, and the vertical axis is attenuation. The resonance frequency in each coil length when width La1 of the coil pattern 101 is changed between 0.1 mm (refer FIG. 12)-0.3 mm is shown.

  When the width La1 of the coil pattern 101 is 0.3 mm, the lowest resonance frequency f0 = 1.42 GHz. When the width La1 is 0.2 mm, f0 = 1.55 GHz, and when the width La1 is 0.1 mm, f0 = 1.9 GHz. Become. Thus, f0 moves to the high frequency side as the width La1 of the coil pattern 101 is reduced. That is, an arbitrary f0 can be obtained by setting the width La1 of the coil pattern 101 that matches the desired f0. Further, the frequency characteristics of the high frequency can be adjusted by changing the total length of the coil pattern 101.

  Further, if a plurality of sets of land patterns 112 and meander patterns 122, which are EBGs 102, are provided on a plurality of layers of the printed circuit board and the EBGs 102 of the respective sets are set to have different inductances and capacities, they differ for each set of EBGs 102. f0 can be obtained. A choke coil 100 having a wide frequency characteristic (attenuation characteristic) at a high frequency can be obtained by different f0 for each EBG 102.

  FIG. 14 is a side view illustrating a configuration example of a printed board including the choke coil according to the embodiment. On the printed board 1401, the power supply terminals of the ICs 1402 and 1403 are mounted via surface mounting bumps 1402a and 1403a. A power supply connector may be mounted instead of the IC 1403. For example, a power supply IC (not shown) is mounted on the printed circuit board 1401, and power is supplied from the power supply IC to the power supply line 1405.

  The printed circuit board 1401 is provided in an electronic device (not shown) and supplies power to each part of the electronic device. Electronic devices include communication devices that handle high frequencies, such as mobile phone terminals. The mobile phone terminal is required to reduce the size of the built-in printed circuit board 1401.

  The printed board 1401 is a multilayer board and has a plurality of layers. A power supply line 1405 is formed in a predetermined layer of the printed circuit board 1401, and the power supply line 1405 is connected to power supply terminals (bumps 1402 a and 1403 a) of the ICs 1402 and 1403 through vias 1404. The power line 1405 has a predetermined wiring pattern when viewed from the plane of the printed circuit board 1401.

  Of the layers of the printed circuit board 1401, some regions of the plurality of layers are used as the choke coil 100 described above. In the choke coil 100 shown in this figure, a total of four layers (first layer 301 to fourth layer 304) are used among the layers of the printed circuit board 1401, and the EBG 102 includes a pair of land patterns 112 and meander patterns 122. A land pattern 112 is provided on the second layer 302, and a meander pattern 122 is provided on the third layer 303. In FIG. 14, reference numerals are assigned to the four layers used in the choke coil 100. Then, one input terminal 101A of the choke coil 100 is connected to the via 1404 connected to the power line 1405, and the other output terminal 101B is connected to the IC 1402 via the via 1404.

  Thus, since the choke coil 100 is formed in a pattern on the inner layer of the printed circuit board 1401, it can be formed directly below the electronic component on the printed circuit board 1401, and the mounting space on the printed circuit board 1401 can be eliminated.

  In the illustrated example, the power supply line 1405 is led out to the surface of the printed circuit board 1401 by the via 1404 and connected to the chip coil 1406 on the printed circuit board 1401. The chip coil 1406 is connected to the choke coil 100 in series.

  FIG. 14 shows an example in which the choke coil 100 is formed using a partial region (inner layer) of the printed board 1401 on which electronic components such as the IC 1402 are mounted. The choke coil 100 according to the embodiment can be configured as a single unit as an electronic component of inductance, or can be configured with a printed circuit board having the coil pattern 101 and the EBG 102 shown in FIG. 1, in this case, as described above. The overall dimensions of the choke coil 100 can be made small with a width W1 = 1.7 mm, a length La = 2.2 mm, and a thickness d = 0.4 mm.

  As another configuration example of the choke coil 100, the EBG 102 is formed on a rod-shaped substrate. Then, the coil pattern 101 is wound around the substrate of the EBG 102 in a coil shape using a metal conductor (conductive wire). The cross section of the choke coil 100 (coil pattern 101) can be circular, for example. The metal conductor that is the coil pattern 101 may be covered with an outer skin having a predetermined dielectric constant and electrically insulated from the EBG 102.

  FIG. 15 is a table showing frequency characteristics obtained by combining the choke coil and the chip coil according to the embodiment. By using the choke coil 100 according to the embodiment, a steep attenuation characteristic (see FIG. 12) having a predetermined f0 can be obtained. Further, the general-purpose (conventional) chip coil 1406 has a gentle and relatively wide frequency characteristic (attenuation characteristic). Therefore, by combining the choke coil 100 and the chip coil 1406 shown in FIG. 12, in addition to the attenuation characteristic of the choke coil 100, an attenuation characteristic obtained by adding the attenuation characteristic of the chip coil 1406 in a wide frequency band can be obtained. it can. Thereby, the favorable DC cut characteristic which suppressed the power supply noise about a signal component is acquired.

  FIG. 16 is a perspective view showing a configuration example of a choke coil according to another embodiment, and FIGS. 17A and 17B are each layer when the choke coil according to another embodiment is formed using a multilayer printed board. It is a top view which shows the wiring pattern.

  In the embodiment described above, the coil pattern 101 of the choke coil 100 is wound around the length direction X as an axis. In the choke coil 100 of another embodiment, the winding direction of the coil pattern 101 of the choke coil 100 is changed, and the coil pattern 101 is wound spirally in the same plane (in the plane of each layer of the printed circuit board) with the height direction Z as an axis. The structure is turned.

  As shown to (a) of FIG. 17A, in the 1st layer 301, the upper coil pattern 101a is formed in a spiral form from the input terminal 101A to the connection end 101ab.

  Also, as shown in FIG. 17A (b), the land pattern 112 of the EBG 102 similar to that of the above-described embodiment is formed on the second layer 302 and the fifth layer 305. Further, as shown in FIG. 17B (c), the meander pattern 122 of the EBG 102 similar to that of the above-described embodiment is formed in the third layer 303 and the fourth layer 304.

  Also, as shown in FIG. 17B (d), in the sixth layer 306, the lower coil pattern 101b is formed in a spiral shape from the connection end 101ba to the output terminal 101B.

  Then, the connection end 101ab of the upper coil pattern 101a and the connection end 101ba of the lower coil pattern 101b are provided at the same position when seen in a plan view, and these connection ends 101ab and 101ba are connected by a via 1701. According to this coil pattern, the number of vias 1701 can be reduced to the minimum (one) as compared with the configuration of the coil pattern shown in FIG. 1, and the coil pattern 101 can be easily formed.

  Thus, even when the winding direction of the coil pattern 101 of the choke coil 100 is changed, a predetermined coil length (inductance component) can be obtained within a limited area on the printed circuit board, as in the above embodiment. The effect of this can be obtained.

(Bias T circuit using choke coil)
FIG. 18 is a circuit diagram illustrating a bias T circuit including the choke coil according to the embodiment. The bias T circuit 1800 includes three terminals 1801, 1802, and 1803, a capacitor (capacitor) C (1804) connected in series between the terminals 1801 and 1802, and an inductor L (connected in series between the terminals 1801 and 1803). 1805).

  The signal terminal 1801 receives a PLC signal in which the signal and the DC power are superimposed, the DC power is output from the terminal 1803, and the signal from which the DC component is cut is output from the terminal 1802. If a signal is input from the terminal 1802 and a DC power is input from the terminal 1803, a PLC signal in which the signal and the DC power are superimposed can be output from the terminal 1801.

  The choke coil 100 described above can be used as the inductor L (1805) of the bias T circuit 1800. Here, if the width La1 or the total length of the coil pattern 101 is changed, a bias T circuit 1800 having a different f0 can be obtained.

  In addition, if a plurality of sets of land patterns 112 and meander patterns 122 of the EBG 102 are provided in a plurality of layers of the printed circuit board and different f0 is set for each set, a bias T circuit having a wide band frequency characteristic (DC cut characteristic) 1800 can be obtained.

  As described above, the choke coil 100 can be formed in a pattern on the inner layer of the printed circuit board 1401 (see FIG. 14). Further, a chip coil 1406 and a capacitor 1804 can be provided on the printed circuit board 1401 as an inductor L (1805) as necessary. As described above, by using the choke coil 100 in the inner layer of the printed circuit board 1401 as the bias T circuit 1800, the space of the printed circuit board 1401 can be used effectively, and the bias T circuit 1800 can be downsized.

  Generally, a choke coil uses a wire (inductor) wound around ferrite, but this choke coil is not used in a high-frequency circuit because of a small amount of attenuation at high frequencies. Further, when the frequency band becomes wide, a plurality of choke coils from high frequency to low frequency are required, and the mounting space for chip components on the printed board increases. In this regard, the choke coil 100 of the embodiment can be formed in a pattern on the inner layer of the printed circuit board 1401, and thus can be applied to a high-frequency circuit and a wide frequency band.

  In the above example, the example in which the choke coil 100 is formed in the inner layer of the printed circuit board used for the bias T circuit 1800 has been described. However, the choke coil 100 is not limited to the bias T circuit 1800 and is used as an inductor of various electronic devices. Can be used. Even in this case, since the choke coil can be formed by using the inner layer of the printed circuit board on which various electronic components are mounted, it is possible to reduce the size of the printed circuit board and increase the mounting space for the electronic components. it can.

(Configuration example of communication device provided with bias T circuit)
FIG. 19 is a circuit diagram illustrating a configuration example of a communication device including a bias T circuit having a choke coil according to an embodiment. The communication device 1900 performs communication between the vehicle 1901 and the mobile phone terminal 1911 in a vehicle such as an automobile, and power supply from the vehicle 1901 to the mobile phone terminal 1911. The communication device 1900 includes a circuit inside the vehicle 1901 and a communication unit 1921 connected to the vehicle 1901.

  A transmission unit 1902 and a reception unit 1903 are provided on the vehicle 1901 side, and transmit and receive signals to and from a network such as a mobile phone network outside the vehicle 1901. These transmission unit 1902 and reception unit 1903 are connected to a splitter 1904, and are connected to an input / output terminal (eg, cigarette writer socket) 1905 of a vehicle 1901 via a bias T circuit 1800.

  The splitter 1904 is connected to the terminal 1802 of the bias T circuit 1800, and signals are input and output. A DC power supply is supplied from a DC power supply 1906 to a terminal 1803 of the bias T circuit 1800, and a PLC signal in which the signal and the DC power supply are superimposed is output from the terminal 1801.

  By connecting an electronic device to an input / output terminal (eg, cigarette lighter socket) 1905 of the vehicle 1901, the electronic device can communicate with an external wireless communication network via the vehicle 1901. A DC power supply for operating an electronic device can be received from the vehicle 1901.

  In the illustrated example, the signal terminal 1922 of the communication unit 1921 is connected to the input / output terminal (eg, cigarette lighter socket) 1905 of the vehicle 1901, and signal input / output and DC power supply to the mobile phone terminal 1911 are performed via the communication unit 1921. I do.

  The communication unit 1921 has a signal terminal connected to the terminal 1801 of the bias T circuit 1800, and receives a PLC signal in which a signal and a DC power source are superimposed. The bias T circuit 1800 outputs a DC cut signal from the terminal 1802 and outputs a DC power from the terminal 1803 via the power line 1925. A plurality of antennas 1924 are connected to the terminal 1802 through a splitter 1923. The antenna 1924 transmits and receives signals to and from the mobile phone terminal 1911 by short-range wireless such as Bluetooth (registered trademark).

  Alternatively, the antenna 1924 may not be provided and the antenna line may be connected to the antenna terminal of the mobile phone terminal 1911. Further, the DC power source can supply power to the mobile phone terminal 1911 by non-contact power supply by a non-contact power supply unit 1926 by electromagnetic induction or by power supply connector connection.

  For example, in the numerical example of each component described above, the transmission frequency of the transmission unit 1902 and the reception unit 1903 is 900 MHz, the IF frequency is 400 kHz, the DC power supply voltage is 1.0 V, the center frequency of the antenna 1924 is 1 GHz, and the bias T circuit 1800 Capacitor C is 1.0 pF and inductor L is 1.0 nH.

  Currently, the communication frequency used by the mobile phone terminal 1911 is, for example, a wide band of 200 MHz to 2.5 GHz. In particular, if the choke coil 100 required in the high frequency band of 1 GHz to 2.5 GHz is obtained with a chip coil, the amount of attenuation is small and the current resistance is also small. In this regard, according to the embodiment, the choke coil 100 having a high frequency of 1 GHz to 2.5 GHz can be reduced in size while having high current resistance and high attenuation characteristics.

  In the above configuration example, PLC communication is performed between the vehicle 1901 and the communication unit 1921, and the vehicle 1901 and the communication unit 1921 are each provided with a bias T circuit 1800. By using the choke coil 100 in the inner layer of the printed circuit board 1401 as the bias T circuit 1800, the space of the printed circuit board 1401 can be used effectively, and the bias T circuit 1800 can be downsized. As a result, both the communication device 1900 having the bias T circuit 1800 (the vehicle 1901 side device and the communication unit 1921) can be downsized.

  The communication device 1900 of the above configuration example is configured to be interposed between the vehicle 1901 and the mobile phone terminal 1911 and transfer communication data and the like to each other. The communication apparatus according to the embodiment is not limited to this, and may be configured to include at least the choke coil 100 and not include the bias T circuit 1800. For example, the mobile phone terminal 1911 itself having the choke coil 100 therein can also be used as a communication device. This communication apparatus has a choke coil 100, has a high frequency characteristic (attenuation characteristic), and can be miniaturized. The communication device is not limited to the mobile phone terminal 1911 and can be widely applied to various communication terminal devices and transmission devices that require a choke coil.

  FIG. 20 is a diagram illustrating a communication device having the choke coil according to the embodiment. In this example, a configuration example of the communication device 1900 illustrated in FIG. 19 will be described.

  A communication unit 1921 of the communication device 1900 is provided in the pocket 2001 portion of the vehicle 1901, and a PLC signal is transmitted from the device on the vehicle 1901 side to the communication unit 1921. In this case, the PLC transmission path inside the vehicle may be used without using the input / output terminal (for example, cigarette lighter socket) 1905 of the vehicle 1901.

  Then, a mobile phone terminal 1911 (for example, a smartphone 1911a or a conventional mobile phone 1911b) can be accommodated in the pocket 2001. In this pocket 2001, for example, a non-contact power feeding portion 1926 is provided on the bottom surface, and an antenna 1924 is provided on the side surface. By accommodating the mobile phone terminal 1911 in the pocket 2001, it is possible to easily transmit and receive signals and supply DC power to the mobile phone terminal 1911 when the communication device 1900 and the mobile phone terminal 1911 are in a non-contact state (no connector connection or the like). You can do it.

  The entire interior of the vehicle 1901 is covered with metal, and radio waves of the mobile phone terminal 1911 are not easily connected. Further, when the navigation function of the mobile phone terminal 1911 is used, the radio wave condition is unstable, and the position accuracy is deteriorated during tunnel traveling. There are techniques for performing in-vehicle wireless communication such as wireless LAN, but in-vehicle wireless communication is not safe in terms of communication speed because of slow communication, signal propagation to adjacent vehicles, and interference. In this regard, by using the communication device 1900 described above, the mobile phone terminal 1911 can stabilize the communication state, and can perform safe data transmission / reception.

  According to the embodiment described above, the choke coil structure is provided in which the EBG is provided in the internal space of the coiled conductor pattern according to the CRLH principle. The EBG is composed of a combination of a land pattern and a meander pattern, and has an inductance and a capacitance connected in parallel to the choke coil. When the magnetic flux from the conductor pattern enters the EBG, a repulsive magnetic field that cancels the incident magnetic field is created on the EBG, and the induced current is induced according to the principle of electromagnetic induction, and the current is cut off by the capacitance. This capacitance results in a reverse current, which forms a closed circuit of the LC resonator. Due to the reverse induced current, the permeability changes in the repulsive magnetic field, and the incident electromagnetic wave of the EBG resonates with the EBG and is absorbed. The absorbed action is an effect of changing the magnetic permeability. The magnetic field absorption effect is an effect that the permeability is negative, the refractive index that defines the metamaterial is negative, and the EBG has a metamaterial structure. The EBG acts as a magnetic band gap that separates magnetic flux generated by the current flowing through the conductor pattern. Thereby, a choke coil having a high attenuation in a high frequency band can be obtained by downsizing.

  The choke coil can be formed using a plurality of layers of a multilayer printed board. For example, a coil pattern can be formed as a conductor pattern in the first layer and the sixth layer, and a predetermined coil length can be formed in a small space by via-connecting between the conductor patterns of the first layer and the sixth layer. A set of land patterns and meander patterns of the EBG are formed on the second and third layers. Further, another set of meander pattern and land pattern of EBG is formed on the intermediate fourth layer and fifth layer. If the EBG is formed with a pair of meander pattern and land pattern, a choke coil can be formed with a total of four layers.

  Thus, even when the conductor pattern of the choke coil is formed on the thin printed circuit board, the action of the EBG canceling the magnetic force due to the magnetic flux from the upper and lower layers of the coil pattern can be attenuated, and the inductance amount of the coil pattern can be reduced. Has the effect of not changing. In addition, a choke coil can be formed at low cost by using a printed circuit board.

  The resonance frequency of the choke coil is determined based on the coil pattern and the inductance and capacitance of the EBG. Since the coil pattern and the EBG are arranged so as to overlap in the same printed circuit board, for example, an arbitrary resonance frequency can be easily obtained by changing the region (length or width) of the choke coil. In particular, a high-frequency choke coil can be provided in a printed circuit board in a space-saving manner.

  Further, since the resonance frequency of the choke coil can be obtained corresponding to the capacitance and inductance of the EBG, the resonance frequency corresponding to any capacitance and inductance can be easily obtained. Furthermore, a plurality of sets of EBGs may be provided in the intermediate layer of the printed circuit board, and the capacitance and inductance may be different in each set. Thereby, it is possible to obtain a choke coil having a high frequency and a wide frequency characteristic (attenuation characteristic) by superimposing different resonance frequencies for each set of EBGs by using a single printed board.

  The bias T circuit having the choke coil and the communication device having the bias T circuit according to the embodiment can be miniaturized by a space-saving choke coil. For example, even in a configuration in which a large number of choke coils are incorporated, a plurality of choke coils can be provided inside the device.

  The following additional notes are disclosed with respect to the embodiment described above.

(Supplementary Note 1) A coil pattern provided between input and output terminals and wound in a coil shape;
A magnetic band gap disposed in the internal space of the coil pattern,
The magnetic band gap is
A land pattern formed by connecting a plurality of lands that divide the area of the internal space with connecting pieces;
A meander pattern, which is arranged to be spaced apart from the land pattern by a predetermined distance and meanders the conductor pattern to form an annular shape;
A choke coil characterized by comprising:

(Supplementary note 2) The choke according to supplementary note 1, wherein a base material having a predetermined dielectric constant is provided between the conductor pattern and the land pattern and the meander pattern of the magnetic band gap. coil.

(Additional remark 3) The said base material is a multilayer printed circuit board,
The coil pattern includes a plurality of conductor patterns formed in an upper layer and a lower layer of the printed circuit board, and vias connecting both ends of the plurality of conductor patterns in the upper layer and the lower layer at the same position. Consists of
The choke coil according to appendix 2, wherein the land pattern and the meander pattern of the magnetic band gap are formed of conductor patterns respectively formed in different layers of the intermediate layer of the printed circuit board.

(Appendix 4) The base material is a multilayer printed circuit board,
The coil pattern includes a spiral conductor pattern formed in the plane of the upper layer and the lower layer of the printed circuit board, and vias connecting the ends of the conductor patterns of the upper layer and the lower layer. And consists of
The choke coil according to appendix 2, wherein the magnetic band gap is made of a conductor pattern formed in an intermediate layer of the printed circuit board.

(Supplementary Note 5) The choke coil according to Supplementary Note 3 or 4, wherein a predetermined resonance frequency is obtained based on a width or a total length of the coil pattern formed on the printed circuit board.

(Supplementary note 6) The choke coil according to supplementary note 5, wherein the magnetic band gaps having different resonance frequencies are provided in a plurality of intermediate layers of the printed circuit board.

(Supplementary note 7) Supplementary notes 3 to 6, wherein the conductive pattern and the magnetic band gap are provided using a plurality of layers in a partial region of a multilayer printed board on which a predetermined electronic circuit is mounted. The choke coil according to any one of the above.

(Supplementary Note 8) A bias T circuit comprising the choke coil described in any one of Supplementary notes 1 to 7.

(Supplementary note 9) A communication apparatus comprising the bias T circuit described in supplementary note 8.

(Additional remark 10) The communication apparatus provided with the choke coil as described in any one of additional marks 1-7.

100 Choke coil 101 Coil pattern 101A One end (input terminal)
101B The other end (output terminal)
101a Upper coil pattern 101b Lower coil pattern 101c, 101d Side coil pattern 102 Magnetic band gap (EBG)
112 land pattern 112a land 112b connecting piece 122 meander pattern 122a conductor pattern 301 first layer 302 second layer 303 third layer 304 fourth layer 305 fifth layer 306 sixth layer

Claims (9)

A coil pattern provided between the input and output terminals and wound in a coil shape;
A magnetic band gap disposed in the internal space of the coil pattern,
The magnetic band gap is
A land pattern formed by connecting a plurality of lands that divide the area of the internal space with connecting pieces;
A meander pattern, which is arranged to be spaced apart from the land pattern by a predetermined distance and meanders the conductor pattern to form an annular shape;
A choke coil characterized by comprising:   The choke coil according to claim 1, wherein a base material having a predetermined dielectric constant is provided between the conductor pattern and the land pattern and the meander pattern of the magnetic band gap. The substrate is a multilayer printed circuit board;
The coil pattern includes a plurality of conductor patterns formed in an upper layer and a lower layer of the printed circuit board, and vias connecting both ends of the plurality of conductor patterns in the upper layer and the lower layer at the same position. Consists of
3. The choke coil according to claim 2, wherein the land pattern and the meander pattern of the magnetic band gap are each formed of a conductor pattern formed in a different layer of the intermediate layer of the printed circuit board. The substrate is a multilayer printed circuit board;
The coil pattern includes a spiral conductor pattern formed in the plane of the upper layer and the lower layer of the printed circuit board, and vias connecting the ends of the conductor patterns of the upper layer and the lower layer. And consists of
The choke coil according to claim 2, wherein the magnetic band gap is made of a conductor pattern formed in an intermediate layer of the printed circuit board.   5. The choke coil according to claim 3, wherein a predetermined resonance frequency is obtained based on a width or a total length of the coil pattern formed on the printed circuit board.   6. The choke coil according to claim 5, wherein the magnetic band gaps having different resonance frequencies are provided in a plurality of intermediate layers of the printed circuit board.   The conductive pattern and the magnetic band gap are provided by using a plurality of layers in a partial area of a multilayer printed board on which a predetermined electronic circuit is mounted. The choke coil according to one.   A bias T circuit comprising the choke coil according to claim 1.   A communication apparatus comprising the bias T circuit according to claim 8.

Images