JPS62176111A - High-frequency transformer - Google Patents

Abstract

PURPOSE:To make a balancer hard to be influenced strongly by a conductive layer for electromagnetic field, even if it is arranged in the vicinity of a toroidal type coil, and yet to enable a thin type electromagnetic shielding, by closely coupling a multiple number of thin toroidal type coils having a rectangular cross section, using either a both-side or multilayer circuit substrate. CONSTITUTION:In the balancer, for instance, the primary winding consists of radial conductors 3A, 4A, 3C, 4C, 3E, 4E, etc. and thru-holes 5A, 6A, 5C, 6C, 5E, 6E, etc., having their electrodes 7A, 7B. The secondary winding consists of radial conductors 3B, 4B, 3D, 4D, 3F, etc. and thru-holes 5B, 5B, 5D, 6D, 5F, 6F, etc., having their electrodes 7C, 7D (central tap electrode), 7E. As mentioned above, this balance is of a close coupling of two pairs of toroidal type coils having a rectangular cross section. The main magnetic flux generated by a current running through the primary and secondary windings composes a closed magnetic route and is confined in the insulator 2 parallel with the substrate surface and composing the substrate. For this reason, even arranging a conductive layer for electromagnetic shield in the vicinity of the balancer can hardly influence the balancer strongly.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention mainly relates to a high-frequency transformer and balun (hereinafter, both are collectively referred to as high-frequency transformers) that utilize a double-sided circuit board.
It is related to.

BACKGROUND OF THE INVENTION In recent years, there has been a marked trend toward smaller and thinner electronic devices, and as a result, there has been a strong demand for smaller and thinner high-frequency circuit blocks such as receiver front-end sections and chainer sections that make up these devices. I've become stronger.

One of the challenges in making these high frequency circuit parts smaller and thinner is to make the coils and high frequency transformers smaller and thinner, and to make thin TL magnetic shields possible. Among these coils, efforts have been made in recent years to make them smaller and thinner as one-dress tinop coils or printed coils, but sufficient consideration has not yet been given to high frequency transformers.

The present invention aims to realize a high frequency transformer that can be thinly shielded based on a printed coil.
A conventional printed coil will be explained.

FIG. 5 is a pattern diagram of a planar printed coil that has been commonly used in the high frequency field.

In FIG. 4, 11 is a circuit board, and 12 is a conductor pattern formed on its surface, which functions as a printed coil. The center of the 12 conductor patterns, together with the outermost end of the conductor pattern, becomes the coil terminal, so when in use it is connected to other circuit parts using through holes or jumper wires, but the details are not shown in the figure. will be omitted.

Regarding the above-mentioned printed coils, for example, H and G.

Dill, Design Inductors for Spinfilm Applications: Electrison Design Section 52, February 17, 1964 (Design
ing Iudnctors For Thin
-Film Applications: Elect
ronic DesignP52 Feb, 17.
1964.

Problems to be Solved by the Invention The problem when forming a high-frequency transformer based on the planar printed coil shown in Figure 5 is that the main part of the magnetic flux generated by the current flowing through the coil is perpendicular to the surface of the circuit board. Therefore, if a conductor or magnetic material is placed close to a circuit board that has a high-frequency transformer formed based on this coil, the influence will be strong (and the primary and secondary parts of the high-frequency transformer will be
The problem is that it is difficult to provide a thin electromagnetic shield because the next-side inductance, Q, changes significantly.

Means for Solving the Problems When forming intermittent radial conductors facing both sides of a circuit board, each starting point of each radial conductor on the front and back sides faces on the same circumference, and the radial conductors The end points of are arranged on the same circumference that is concentric with the circumference connecting the above starting points and have different diameters, and the end points corresponding to the starting points facing each other on the front and back sides are Form radial conductors on the front and back surfaces so as to correspond to the adjacent end points (M is a positive integer of 2 or more), and each starting point of the radial conductors on the front and back surfaces facing each other,
By connecting the end points to each other through holes, M independent toroidal coils with a rectangular cross section and each winding are closely coupled to each other are formed. -Next S cotton, secondary winding,...
...Used as the Mth winding. Further, taps are provided at arbitrary locations on each winding to form a balun or the like.

Furthermore, the above-mentioned high frequency transformer is formed using the inner layer conductor of the multilayer circuit board, and the conductor layer adjacent thereto is used as a conductor layer for electromagnetic shielding.

Function The present invention solidly forms a plurality of thin toroidal coils having a rectangular cross section as described above to have the function of a high frequency transformer. By creating a closed magnetic path in parallel directions, the influence of conductor layers even if they are placed close to each other is reduced, thereby realizing a high frequency transformer capable of thin electromagnetic shielding.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view conceptually showing the structure of a high frequency transformer according to the present invention, taking a balun as an example.

In FIG. 1, IA, 18 are front and back conductor layers of a double-sided circuit board, 2 is an insulator, 3A to 3u shown by solid lines are radial conductors formed on the front conductor layer, and 4A to 4A shown by dotted lines are shown in FIG.
4. 5A to 5. are radial conductors formed on the back conductor layer.
and 6A-61. I is each line 3A of radial conductor
~3° and 4A~ Through holes for electrically connecting the ends of the starting and ending points, and 7A to 7E represent the electrodes of the balun.

In the balun shown in Figure 1, the primary winding consists of radial conductors 3A, 4
A, 3o, 4c, 36.4E, 30°4o, 3. ．． 4.
．． 3. ．． 4, 3. ．． 4. and through hole SA, 6
A, 5o, 6o, 58°6°, 5o, 6o, 5. ．． 6.
．． 5, 6K.

5. 6. 7A and 7B are the electrodes, and the secondary windings are radial conductors 3B, 4B, 38° 4D, 3F,
4F・3H・4H・3J・4J・3L, 4L
and through hole 58.6B, 5. .

6D・5F・6F・5H・6H・5J・6
It is composed of J, 5L, and 6L, and 7c, 7[), and 78 are its electrodes (7, is the center tap electrode).

As is clear from Figure 1, this balun consists of two sets of toroidal coils with a thin rectangular cross section, tightly coupled together, and the main magnetic flux generated by the current flowing through the -order S wire and the secondary winding is directed to the substrate surface. Since the balun is parallel to the balun and is confined to form a closed magnetic path within the insulator that makes up the board, even if an electromagnetic shielding conductor layer is placed close to the balun, the balun is not strongly affected by it. Therefore, it is possible to create a balun with a thin electromagnetic shield. FIG. 2 shows a plan view of the balun shown in FIG. 1, and since each number attached to the figure is the same as that in FIG. 1, further detailed explanation will be omitted.

FIG. 3 is a perspective view conceptually showing the structure of a balun that uses a four-layer circuit board and is thin and magnetically shielded.
Portions designated by the same numbers as in the figures have the same functions and structures as those in FIG. 1, so further detailed description will be omitted. In FIG. 3, 8A to 8D are the first sections of the multilayer circuit board, respectively. 2nd゜3rd. Indicates the fourth conductor layer, 9A to 96
In order to take out the balun electrode to the outside, the first conductor layer and the second
A through hole for electrically connecting radial conductors formed in the conductor layer or the third conductor layer. 10A.

108 is a through hole for electrically connecting the first conductor layer and the fourth conductor layer used for electromagnetic shielding, and 20A to 208 are parts of the 1i-th body layer used for electromagnetic shielding. This shows the balun electrode provided in the part where the island shape has been removed.

FIG. 4 is a perspective view showing the external appearance when a balun is formed inside the four-layer circuit board shown in FIG.
Since the parts designated by the same numbers as in the figures have the same functions and structures as those in FIG. 3, further detailed description will be omitted.

In the above explanation, a balun having a secondary winding with a center socket was used as an example. However, as is clear from the figure, it is possible to provide a tertiary winding, a quaternary winding, eliminate a tap, or Needless to say, the present invention includes the provision of the winding at any point of the winding.

Furthermore, in order to increase the inductance, Q, and degree of coupling of each winding, based on the purpose of the present invention, a filler made of a magnetic material is introduced into the insulator of the circuit board, and the magnetic material itself has good insulation properties. Of course, it is possible to take any other measures, such as introducing the system.

Effects of the Invention As described above, the present invention uses a double-sided circuit board, a multilayer circuit board, and a plurality of sets of thin toroidal type foils having a rectangular cross section.
A high-frequency transformer is constructed by tightly coupling the transformer, and the main magnetic flux generated by the current flowing through each winding of the transformer is parallel to the substrate surface and is confined by forming a closed magnetic path within the insulator that makes up the substrate. Even if a conductor layer for electromagnetic shielding is placed close to this high-frequency transformer, it is less susceptible to the influence, and a high-frequency transformer capable of thin electromagnetic shielding can be obtained.

[Brief explanation of drawings]

Figure 3 is a perspective view conceptually showing the structure of a balun that uses a 4N circuit board and is provided with a thin electromagnetic shield.
FIG. 5 is a perspective view showing the external appearance of a 4N circuit board shown in which a balun is formed inside the circuit board, and FIG. 5 is a perspective view showing a conventional planar printed coil. IA, 1. ,...Front surface of double-sided circuit board, back conductor layer, 2...Insulator, 3A to 3 construction...
Radial conductor formed on the surface conductor layer, 4A~4°...
. . . Radial conductor formed on the back conductor layer, 5A to 5° . . . Surface. The radial pattern formed between the conductor layers on the back side, and...
・6A to 6o...Through holes that electrically connect each starting point and end point of the conductor, 7A to 78...
- Balun electrode, 8A-8. ...Conductor layer of 4-layer circuit board, 9A to 9E...Through hole for taking out the balun electrode to the outside, ■OA, 10B...
・Through hole connecting between conductors for electrode shield, 2
0A~208...Balun electrode, 11...
...Circuit board, 12...Conventional planar printed coil conductor pattern. Name of agent: Patent attorney Toshio Nakao, 1 person δA ---
Ya 1 Ki Jukan 8B-11su 2 De δ. -1-su3・Figure 3 δD-ri→・9a-9E---+r21iLiijlt1. rJI
ff; f firing: □, 'H';, :h&:! -;-L2θ~
FOR-Barano Ren A

Claims (3)

[Claims] (1) When forming interrupted radial conductors facing both sides of a circuit board, each starting point of each radial conductor on the front and back sides is opposite on the same circumference, and each radial conductor on the front and back sides is The end points are arranged on the same circumference that is concentric with the circumference connecting the above starting points and have different diameters, and the end points corresponding to the starting points facing each other on the front and back sides are on the front and back sides, respectively. Form radial conductors on the front and back surfaces so that they correspond to the adjacent end points (M is a positive integer of 2 or more), and connect the opposing starting and ending points of the radial conductors on the front and back sides through holes. By doing so, M independent toroidal coils having a rectangular cross section and each winding are tightly coupled to each other are formed. is a positive integer of 1 or more). (2) A high-frequency transformer according to claim (1), characterized in that a tap is provided at an arbitrary position on each winding of M coils. (3) Form an insulating layer covering the entire area where the interrupted radial conductor pattern is formed on the front and back surfaces, further cover it to form a conductor layer, and use this conductor layer as a conductor for electromagnetic shielding of a high frequency transformer. The high frequency transformer according to claim (1), which is used as a layer.