JP2004193886A - Bias t - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a bias T having proper productivity, a small size and stable characteristics. <P>SOLUTION: In the bias T 10, a capacitor C in which a pair of high frequency capacitors 12a, 12b and a low frequency capacitor 14 connected in series are connected in parallel, is connected between a first terminal 1 and a second terminal 2, and a coil L is connected between the second terminal 2 and a third terminal 3. Further, a first conductor pattern 32 and a second conductor pattern 33 are oppositely disposed on the surface of a dielectric substrate 30, an internal electrode 34 superposed with the first and second conductor patterns is disposed in the dielectric substrate 30, and the pair of the high frequency capacitors 12a, 12b are formed between the first conductor pattern 32 and the internal electrode 34, and between the second conductor pattern 33 and the internal electrode 34. One electrode 14a of the low frequency capacitor 14 made of a ceramic capacitor is connected to the first conductor pattern 32, and the other electrode 14b is connected to the second conductor pattern 33 to constitute the capacitor C, and a lead wire 20 is wound on the outer peripheral surface of the winding 24 of a conical core 22 to constitute the coil L. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bias T for superimposing and supplying a DC component such as a DC current or a DC voltage without affecting a high-frequency signal.
[0002]
[Prior art]
A bias T as an electronic component for supplying a DC component such as a DC current or a DC voltage in a superimposed manner without affecting a high-frequency signal has been conventionally used as disclosed in JP-A-9-8583. I have.
As shown in FIG. 8, the bias T70 is configured by connecting a capacitor C ′ between terminals a and b and connecting a coil L ′ between terminals a and c.
The bias T70 passes a high-frequency signal between terminals a and b and removes a low-frequency component by a capacitor C ′. A DC component is input from a terminal c and a high-frequency component is removed by a coil L ′. Overlaid on the high frequency signal.
[0003]
9 and 10 show an example of a coil L 'used for the bias T70. This coil 74 has an insulating coating 78 made of a polymer insulating material such as polyester or polyurethane on the surface of the copper wire 76. The conductive wire 80 is wound around an outer peripheral surface of a cylindrical core 82 made of a magnetic material such as dielectric ceramic or ferrite. In addition, both ends of the conductive wire 80 are formed as terminal portions 84 by exfoliating the insulating coating 78 and exposing the copper wire 76.
In the coil 74, the core 82 has a cylindrical shape, and the winding diameter of the conductive wire 80 wound around the core 82 is constant at any portion, so that the coil has only one self-resonant frequency. . As a result, as shown in the graph of FIG. 11, the impedance of the coil 74 becomes maximum at its self-resonant frequency, and at a frequency equal to or higher than the self-resonant frequency, the impedance sharply decreases, and the coil does not perform its function. However, a single coil 74 could not be used in a wide band.
[0004]
Therefore, when the coil 74 is used for the bias T70 for a wide band, a plurality of coils 74a, 74b, 74c, 74d having different self-resonant frequencies are connected in series as shown in the graph of FIG. A coil usable in a wide band as shown by a solid line in the graph of FIG. 12 was configured.
[0005]
Further, as shown in FIG. 13, the capacitor C ′ used for the bias T70 for a wide band is configured by connecting a capacitor 86 for a high frequency and a capacitor 88 for a low frequency in parallel to constitute a capacitor usable in a wide band. Was.
The high frequency capacitor 86 and the low frequency capacitor 88 are composed of, for example, ceramic chip capacitors.
Then, as shown in FIG. 14, one electrode 86a of the high-frequency capacitor 86 is connected to the conductor pattern 92a on the surface of the circuit board 90, and the other electrode 86b is connected via an external electrode terminal 94 made of copper foil or the like. Connected to a conductor pattern 92b on the surface of the circuit board 90, and one electrode 88a of the low-frequency capacitor 88 is connected to the conductor pattern 92b on the surface of the circuit board 90 via the external electrode terminal 94. The other electrode 88b is connected to a conductor pattern 92a on the surface of the circuit board 90 via a conductive base 96 made of copper or the like, so that the high-frequency capacitor 86 and the low-frequency capacitor 88 are mounted on the circuit board 90. Has been done.
[Patent Document 1]
JP-A-9-8583
[Problems to be solved by the invention]
As described above, conventionally, a plurality of coils 74 having different self-resonance frequencies are connected in series to form a coil that can be used for the bias T70 for a wide band. The connection operation for obtaining a coil having stable characteristics by connecting the components is complicated, and the number of parts is increased and the size is increased.
[0007]
Conventionally, a high-frequency capacitor 86 and a low-frequency capacitor 88 composed of ceramic chip capacitors are connected in parallel to form a capacitor that can be used in a wide band, and these high-frequency capacitor 86 and low-frequency capacitor 88 are used. 14 is mounted on the circuit board 90 via the external electrode terminal 94 and the pedestal 96 (FIG. 14). In this case, since the inductance component of the external electrode terminal 94 greatly affects the high frequency characteristics of the high frequency capacitor 86, In addition, in order to prevent the characteristic deterioration as much as possible, it is necessary to perform the connection operation while finely adjusting the length and the mounting position of the external electrode terminal 94, and the connection operation is complicated. Furthermore, since the high-frequency capacitor 86 and the low-frequency capacitor 88 completed as individual components are mounted on the circuit board 90 using the external electrode terminals 94 and the pedestal 96, the number of components is increased, and the shape is large. Was brought to life.
[0008]
The present invention has been devised to solve the above-mentioned conventional problems, and an object of the present invention is to realize a bias T with good productivity, small size and stable characteristics.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a bias T according to the present invention has first to third terminals, and a high-frequency capacitor and a low-frequency capacitor are provided between the first terminal and the second terminal. A capacitor connected in parallel with a frequency capacitor is connected, and a coil is connected between the second terminal and the third terminal or between the first terminal and the third terminal. A bias T comprising: a conductor pattern disposed on the surface of the dielectric substrate; and an internal electrode overlapping the conductor pattern disposed inside the dielectric substrate. The coil is formed by forming a high-frequency capacitor, forming at least one portion having a diameter different from that of the other portion in the winding portion of the core, and winding a conductive wire around the outer peripheral surface of the core. It is characterized by having done.
[0010]
In the coil constituting the bias T of the present invention, at least one portion having a different diameter from the other portions is formed in the winding portion of the core, so that the winding diameter of the conductor wound around the different diameter portion is different from that of the coil. The winding diameter of the conductive wire wound around the other portion is different, and has a plurality of self-resonant frequencies. As a result, a single coil can be used in a wide band. Therefore, in the bias T of the present invention using the coil, the complicated connection work of the plurality of coils 74 as in the conventional bias T70 for a wide band is not required, and the productivity and characteristics are improved. The number of points can be reduced and the size can be reduced.
[0011]
The capacitor constituting the bias T according to the present invention forms a high-frequency capacitor between a conductor pattern disposed on the surface of the dielectric substrate and an internal electrode disposed inside the dielectric substrate and overlapping the conductor pattern. Therefore, there is no need to provide the external electrode terminal 94 for connecting the conductor pattern 92b and the high-frequency capacitor 86 unlike the conventional wide band bias T70. Therefore, in the bias T of the present invention using the capacitor, complicated connection work of the external electrode terminal 94 for preventing deterioration of the high frequency characteristics as in the conventional bias T70 becomes unnecessary, and the productivity and characteristics are improved. In addition, the number of parts can be reduced and the size can be reduced.
[0012]
A first conductor pattern and a second conductor pattern are opposed to each other with a predetermined gap provided on the surface of the dielectric substrate, and the first conductor pattern and the second conductor pattern are arranged inside the dielectric substrate. By arranging the overlapping internal electrodes, a first high-frequency capacitor and a second high-frequency capacitor connected in series between the first conductor pattern and the internal electrode and between the second conductor pattern and the internal electrode. A capacitor may be formed. In this case, the low-frequency capacitor is constituted by a chip capacitor, and one electrode of the low-frequency capacitor is connected to the first conductor pattern constituting the first high-frequency capacitor, and the other electrode is connected to the first conductor pattern. By connecting to the second conductor pattern constituting the second high-frequency capacitor, the low-frequency capacitor, the first high-frequency capacitor and the second high-frequency capacitor can be connected in parallel, so that further production is possible. As a result, the number of parts can be reduced and the size can be reduced.
[0013]
It is desirable that the winding portion of the core of the coil is formed in a conical shape or a pyramid shape.
Thus, when the winding portion of the core is formed in a conical shape or a pyramid shape, the winding diameter of the conductive wire wound around the winding portion gradually decreases or increases from one end to the other end. As a result, a large number of self-resonant frequencies are continuously provided over a wide frequency band, so that a single coil can be used in a wide band.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a bias T according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a circuit diagram of a bias T10 according to the present invention. The bias T10 has a first terminal 1, a second terminal 2, and a third terminal 3; A capacitor C formed by connecting a pair of high-frequency capacitors 12a, 12b and a low-frequency capacitor 14 connected in series is connected between the second terminal 2 and the second terminal 2. 3 is connected to a coil L. Note that the coil L can be connected between the first terminal 1 and the third terminal 3.
[0015]
As shown in FIGS. 2 to 4, the coil L is formed by connecting a conductive wire 20 having a surface of a copper wire 16 on which an insulating film 18 made of a polymer insulating material such as polyester or polyurethane is formed, to a dielectric ceramic, ferrite, or the like. It is wound around the outer peripheral surface of the winding part 24 of the conical core 22 made of a magnetic material.
In addition, both ends of the conductive wire 20 are formed as terminal portions 26 by exfoliating the insulating coating 18 to expose the copper wire 16.
[0016]
In the coil L of the present invention, as described above, the winding portion 24 of the core 22 gradually decreases in diameter from one end (the right end in FIG. 2) to the other end (the left end in FIG. 2). Because of the conical shape, the winding diameter of the conductive wire 20 wound around the winding portion 24 also gradually decreases from one end (the right end in FIG. 2) to the other end (the left end in FIG. 2). It is becoming.
[0017]
As described above, in the coil L of the present invention, the winding diameter of the conductive wire 20 wound around the winding portion 24 gradually increases from one end (the right end in FIG. 2) to the other end (the left end in FIG. 2). As it becomes smaller, as shown in the graph of FIG. 5, it has a large number of different self-resonant frequencies continuously over a wide frequency band. it can.
[0018]
The dimensions of the coil L are, for example, such that the maximum diameter of the winding portion 24 of the core 22 is 1 mm, the length is 2 mm, and the diameter of the conductor 20 is 0.05 mm. The number of turns L was 1 μH.
[0019]
The shape of the winding portion 24 of the core 22 is not limited to the above-described conical shape, but may be a pyramid shape.
Further, in order to form the coil L having a plurality of self-resonant frequencies, at least one portion having a diameter different from other portions is formed in the winding portion 24 of the core 22 around which the conductive wire 20 is wound. It would be fine.
[0020]
FIG. 6 is a schematic sectional view of the capacitor C constituting the bias T10 according to the present invention. The first conductive pattern 32 is formed on the surface of the dielectric substrate 30 from both ends of the dielectric substrate 30 to the inside. The second conductor pattern 33 and the second conductor pattern 33 are arranged facing each other with a predetermined gap therebetween, and an internal electrode 34 partially overlapping the first conductor pattern 32 and the second conductor pattern 33 is provided inside the dielectric substrate 30. By arranging, the first high-frequency capacitor 12 a is formed between the first conductor pattern 32 and the internal electrode 34, and the second high-frequency capacitor 12 a is formed between the second conductor pattern 33 and the internal electrode 34. Is formed.
[0021]
In addition, one electrode 14a of the low-frequency capacitor 14 formed of a ceramic chip capacitor is connected to the first conductor pattern 32 forming the first high-frequency capacitor 12a, and the other electrode 14b is connected to the first electrode 14b. By connecting to the second conductor pattern 33 constituting the second high-frequency capacitor 12b, the low-frequency capacitor 14 and the pair of high-frequency capacitors 12a and 12b connected in series are connected in parallel.
In the first conductor pattern 32 and the second conductor pattern 33, portions that do not overlap with the internal electrodes 34 and do not constitute the high-frequency capacitors 12a and 12b constitute a microstrip line for transmitting a high-frequency signal, and The outer ends of the first conductor pattern 32 and the second conductor pattern 33 are formed as the first terminal 1 and the second terminal 2, respectively.
In FIG. 6, reference numeral 36 denotes a ground electrode formed on the entire back surface of the dielectric substrate 30.
[0022]
The internal electrode 34 is formed by stacking another dielectric substrate 30b on a dielectric substrate 30a having a surface on which a conductor pattern constituting the internal electrode 34 is formed, and then pressing and firing to integrate them. Can be formed.
The dielectric substrate 30 is made of ceramic having a dielectric constant of about 7, and the first conductor pattern 32a, the second conductor pattern 32b, and the internal electrode 34 are made of Ag, Ag-Pd, Au, or the like. Have been.
[0023]
In the capacitor C of the present invention, the conductor patterns 32 and 33 formed on the surface of the dielectric substrate 30 and the internal electrodes 34 formed inside the dielectric substrate 30 and partially overlapping the conductor patterns 32 and 33 are provided. Since the high-frequency capacitors 12a and 12b are formed between them, there is no need to provide the external electrode terminal 94 for connecting the conductor pattern 92b and the high-frequency capacitor 86 unlike the conventional broadband bias T70. In addition, complicated connection work of the external electrode terminals 94 for preventing deterioration of high frequency characteristics is not required, and productivity and characteristics are improved.
The high-frequency capacitors 12a and 12b are formed inside the dielectric substrate 30, and one electrode 14a of the low-frequency capacitor 14 composed of a ceramic chip capacitor is connected to the first conductor pattern 32, and the other electrode 14b is connected to the other. By connecting to the second conductor pattern 33, the low-frequency capacitor 14 and the pair of high-frequency capacitors 12a and 12b can be connected in parallel, so that the number of components can be reduced and the size can be reduced.
[0024]
FIG. 7 is a schematic plan view of the bias T10 according to the present invention, in which the coil L is disposed on the dielectric substrate 30 on which the capacitor C is formed, and the coil L has a smaller winding diameter of the conductive wire 20. Is connected to the second terminal 2 formed at the outer end of the second conductor pattern 33, and the terminal 26 on the side where the winding diameter of the conductive wire 20 is smaller is connected to the dielectric substrate 30. It is integrated by connecting to the third terminal 3 formed by applying a conductor pattern on the surface.
[0025]
In the coil L constituting the bias T10 of the present invention, the winding portion 24 of the core 22 has a conical shape, and the winding diameter of the conductive wire 20 wound around the winding portion 24 increases from one end to the other end. Therefore, the coil L has a large number of self-resonant frequencies continuously over a wide frequency band, so that a single coil L can be used in a wide band. Therefore, in the bias T10 of the present invention using the coil L, complicated connection work of a plurality of coils 74 as in the conventional broadband bias T70 is not required, and productivity and characteristics are improved. The number of parts can be reduced and the size can be reduced.
[0026]
Further, as described above, the capacitor C constituting the bias T10 of the present invention includes the conductor patterns 32 and 33 formed on the surface of the dielectric substrate 30 and the conductor patterns 32 and 33 formed inside the dielectric substrate 30. Since the high-frequency capacitors 12a and 12b are formed between the partially overlapped internal electrodes 34, the external electrode terminals for connecting the conductor pattern 92b and the high-frequency capacitor 86 like the conventional broadband bias T70. There is no need to provide 94. The high-frequency capacitors 12a and 12b are formed inside the dielectric substrate 30, and one electrode 14a of the low-frequency capacitor 14 composed of a ceramic chip capacitor is connected to the first conductor pattern 32, and the other electrode 14b is connected to the other. By connecting to the second conductor pattern 33, the low-frequency capacitor 14 and the pair of high-frequency capacitors 12a and 12b can be connected in parallel.
Therefore, in the bias T10 of the present invention using the capacitor C, the complicated connection work of the external electrode terminal 94 for preventing the deterioration of the high frequency characteristics as in the conventional bias T70 becomes unnecessary, and the productivity and the characteristics are reduced. In addition to the improvement, the number of parts can be reduced and the size can be reduced.
[0027]
【The invention's effect】
In the coil constituting the bias T of the present invention, at least one portion having a different diameter from the other portions is formed in the winding portion of the core, so that the winding diameter of the conductor wound around the different diameter portion is different from that of the coil. The winding diameter of the conductive wire wound around the other portion is different, and has a plurality of self-resonant frequencies. As a result, a single coil can be used in a wide band. Therefore, in the bias of the present invention using the coil, the complicated connection work of the plurality of coils 74 as in the conventional bias T70 for a wide band is not required, and the productivity and characteristics are improved, and the number of parts is reduced. And the size can be reduced.
[0028]
The capacitor constituting the bias T according to the present invention forms a high-frequency capacitor between a conductor pattern disposed on the surface of the dielectric substrate and an internal electrode disposed inside the dielectric substrate and overlapping the conductor pattern. Therefore, there is no need to provide the external electrode terminal 94 for connecting the conductor pattern 92b and the high-frequency capacitor 86 unlike the conventional wide band bias T70. Therefore, in the bias T of the present invention using the capacitor, complicated connection work of the external electrode terminals 94 for preventing deterioration of the high frequency characteristics as in the conventional bias T70 is not required, and productivity and characteristics are improved. In addition, the number of parts can be reduced and the size can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a bias T according to the present invention.
FIG. 2 is a schematic front view of a coil constituting a bias T according to the present invention.
FIG. 3 is a sectional view taken along line BB of FIG. 2;
FIG. 4 is a sectional view taken along the line CC of FIG. 2;
FIG. 5 is a graph showing impedance characteristics of a coil constituting a bias T according to the present invention.
FIG. 6 is a schematic sectional view of a capacitor constituting a bias T according to the present invention.
FIG. 7 is a schematic plan view of a bias T according to the present invention.
FIG. 8 is a circuit diagram showing a conventional bias T.
FIG. 9 is a front view showing a coil used for a conventional bias T.
FIG. 10 is a sectional view taken along line AA of FIG. 9;
FIG. 11 is a graph showing impedance characteristics of a coil used for a conventional bias T.
FIG. 12 is a graph showing impedance characteristics when a plurality of coils used for a conventional bias T are connected in series.
FIG. 13 is a circuit diagram showing a conventional capacitor used for a bias T for a wide band.
FIG. 14 is a schematic cross-sectional view showing a state in which a conventional capacitor used for a bias T for a wide band is mounted on a circuit board.
[Explanation of symbols]
1 first terminal 2 second terminal 3 third terminal 10 bias T
C capacitor L coil 12a first high-frequency capacitor 12b second high-frequency capacitor 14 low-frequency capacitor 20 conductor 22 core 24 winding part 30 dielectric substrate 32 first conductor pattern 33 second conductor pattern 34 internal electrode

Claims (4)

A capacitor having first to third terminals, a capacitor configured by connecting a high-frequency capacitor and a low-frequency capacitor in parallel between the first terminal and the second terminal, and a second capacitor. A bias T formed by connecting a coil between a terminal and a third terminal, or between a first terminal and a third terminal, wherein a conductor pattern is disposed on a surface of a dielectric substrate. By arranging an internal electrode that overlaps with the conductor pattern inside the dielectric substrate, the high-frequency capacitor is formed between the conductor pattern and the internal electrode, and the diameter of the winding portion of the core is different from that of another portion. Wherein at least one or more different portions are formed, and the coil is formed by winding a conductive wire around the outer peripheral surface of the core. A first conductor pattern and a second conductor pattern are opposed to each other with a predetermined gap provided on the surface of the dielectric substrate, and the first conductor pattern and the second conductor pattern are arranged inside the dielectric substrate. By arranging the overlapping internal electrodes, a first high-frequency capacitor and a second high-frequency capacitor connected in series between the first conductor pattern and the internal electrode and between the second conductor pattern and the internal electrode. The bias T according to claim 1, wherein a capacitor is formed. The low-frequency capacitor is constituted by a chip capacitor, one electrode of the low-frequency capacitor is connected to a first conductor pattern constituting a first high-frequency capacitor, and the other electrode is connected to a second electrode. 3. A low-frequency capacitor, a first high-frequency capacitor and a second high-frequency capacitor are connected in parallel by being connected to a second conductor pattern constituting the high-frequency capacitor. Bias T described in 1. The bias T according to any one of claims 1 to 4, wherein a winding portion of the core of the coil has a conical shape or a pyramid shape.

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