JPH11144961A - Surface-mounted equilibrium-nonequilibrium converting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-mounted equilibrium-nonequilibrium converting device for mutual conversion between an equilibrium transmission path and a nonequilibrium transmission path which is extremely downsized. SOLUTION: A first dielectric layer 31 is made of glass ceramics or the like. A first primary strip line 11 is formed on one surface of the first dielectric layer 31. A first secondary strip line 12 is formed on the other surface of the first dielectric layer 31. A first coupled path 1 is comprised of the first primary and secondary strip lines 11 and 12. A second secondary coupled path 2 is comprised of a second primary strip line 21, formed on one surface of a second dielectric layer 32 and a second secondary strip line 22, formed on the other surface of the second dielectric layer 32. The first and second coupled paths 1 and 2 are laminated via a third dielectric layer 33 in the longitudinal direction of the device and are jointed to obtain a surface-mounted equilibrium- nonequilibrium converting device. Although the strip lines can be made linear, they are bent or formed into a spiral shape so as to facilitate downsizing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type balanced / unbalanced conversion element for mutually converting a balanced transmission line and an unbalanced transmission line. The surface-mount type balanced-unbalanced conversion element of the present invention is used for information communication equipment such as a portable transceiver. Further, it can be used as an impedance converter of a high-frequency transmission line or a balun transformer for mutually converting signals of a balanced transmission line and an unbalanced transmission line.

[0002]

2. Description of the Related Art Balance-unbalance conversion elements are used to connect lines having different balances in a high frequency range. The balance-unbalance conversion element includes a coupler including a primary coil and a secondary coil paired with the primary coil. Conventionally, a coil obtained by winding a copper wire around a ferrite core is used as the primary and secondary coils.
However, since the copper wire cannot always be wound uniformly, the characteristics are not stable, for example, the balance of the balanced output is lost. In addition, since the coil is formed by winding a copper wire around the core, there is naturally a limit to miniaturization.

[0003] In order to solve the above-mentioned problems such as unstable characteristics or limited size reduction, there has been proposed a converter in which strip lines are connected by a 1/4 wavelength coaxial line without using a coil. . In this converter, it is necessary to route a coaxial line having a length of 1/4 wavelength. However, since coaxial lines are usually provided only with several types of impedance, there is a problem that an arbitrary conversion ratio cannot be obtained when the coaxial line is used as an impedance converter.

[0004] In order to solve the problem when such a coaxial line is used, Japanese Patent Application Laid-Open No. 8-191016 discloses a primary coil and a secondary coil using a strip line of a specific shape on the surface of a dielectric substrate. There has been proposed a converter having a structure in which a coil is formed and a first coupling line body and a second coupling line body are built in a laminated dielectric substrate. However, in this converter, since the first and second coupling line bodies are arranged on the same plane of the dielectric substrate, the surface area of the converter becomes large, and it is necessary to reduce the mounting area such as a cellular phone. There is a problem that it cannot be used for a certain small communication device.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and the first and second coupled line bodies are not disposed on the same plane as in the prior art. It is an object of the present invention to provide a surface-mounted balanced-unbalanced conversion element having a structure in which layers are stacked in a thickness direction of the element via layers. By adopting such a structure, the surface-mount type balanced-unbalanced conversion element of the present invention can reduce the area in the plane, and is useful in a remarkably miniaturized communication device such as a portable transceiver. is there.

[0006]

According to a first aspect of the present invention, there is provided a surface mount type balanced-unbalanced conversion element comprising: (1) a first dielectric layer; and (2) a first dielectric layer formed on one surface of the first dielectric layer. A first coupled line body including a primary strip line and a first secondary strip line formed on the other surface, and (3) a second dielectric layer;
(4) a second coupled line body including a second primary strip line formed on one surface of the second dielectric layer and a second secondary strip line formed on the other surface; 1
Of the primary strip line and the first secondary strip line, and the second primary strip line and the second secondary strip line.
That the first and second coupling line members are electromagnetically coupled to each other, and that the first and second coupling line members are arranged in the longitudinal direction of the element via a third dielectric layer. Features.

The surface-mount type balanced-unbalanced conversion element according to a second aspect of the present invention includes (1) a first dielectric layer, and (2) a first primary strip line formed on one surface of the first dielectric layer. And a first secondary line formed on the other surface and a first secondary line formed on the other surface, and (3) one surface is laminated on the first secondary strip line, and a first electromagnetic shielding material layer on the other surface. A fourth dielectric layer provided with: (4) a second dielectric layer,
(5) a second coupled line body including a second primary strip line formed on one surface of the second dielectric layer and a second secondary strip line formed on the other surface; and (6) one surface A fifth dielectric layer laminated on the second secondary strip line, and provided on the other surface with a second electromagnetic shielding material layer;
Wherein the first primary strip line and the first secondary strip line, and the second primary strip line and the second secondary strip line are respectively electromagnetically coupled, and The first coupling line body and the second coupling line body are arranged via a third dielectric layer.

[0008] In the first and second inventions, the first coupled line body and the second coupled line body are arranged via a third dielectric layer. The third dielectric layer is composed of two or three dielectric layers, and a connection for connecting an electromagnetic shielding material layer or an unbalanced transmission line to an input / output terminal provided on the surface of the element therebetween. At least one of the lines can be formed. As the electromagnetic shielding material forming the electromagnetic shielding material layer, silver paste, copper paste, or the like is usually used. Further, the above connection lines can also be formed by the same paste. This electromagnetic shielding material layer or connection line can be formed by printing a silver paste or the like on one surface of a sheet made of a dielectric material.

Further, in the second invention, the first secondary strip line and the first electromagnetic shield material layer are connected by the second via hole as in the third invention. Similarly, the second secondary strip line and the second electromagnetic shield material layer are connected by a third via hole. The first and second secondary strip lines and the first and second electromagnetic shield material layers do not necessarily need to be connected by via holes, and the ends of these strip lines are connected to the electromagnetic shield material layer by other means. It may be. However, in particular, if the end of the spiral center of the strip line is connected by a via hole near the center of the electromagnetic shielding material layer, miniaturization becomes easier. still,
The via hole portion means a via hole and a conductive material filled in the inside or coated on the wall surface.

Further, in the first and second inventions, the first primary strip line and the second primary strip line are connected by the first via hole as in the fourth invention. As described above, the element can be more easily miniaturized by being internally connected by the via hole portion. The first and second primary strip lines need not necessarily be connected to each other by the via holes, and the spiral outer ends of these strip lines may be connected by other means.

Also, the first and second primary strip lines and the first and second secondary strip lines can be formed in a straight line. However, as in the fifth invention, it is preferable that all of these strip lines are bent or formed in a spiral shape. In that way, each stripline is not particularly long in one direction. Therefore, the element can be miniaturized, which is useful in a small communication device such as a portable transceiver. The strip line can have an appropriate shape depending on the actual shape or design of the element.

Incidentally, if the first primary strip line, the second primary strip line, the first secondary strip line and the second secondary strip line are all formed to have the same length, it is ideal. Is connected to a balanced transmission line.
The phase difference of the signal between the two input / output terminals becomes 180 degrees. However, in practice, it is extremely difficult to design with high accuracy so that the phase difference becomes 180 degrees. Therefore, the balanced transmission line 2 connected to the two input / output terminals
Noise in one signal line is not canceled out efficiently.

Therefore, the first primary strip line and the first secondary strip line are formed to have the same length,
The first and second primary strip lines are formed to have the same length, and the first and second primary strip lines are formed to have different lengths. Can also be adjusted. In this way, it is also possible to design so that the phase difference of the signal between the first secondary stripline and the second secondary stripline to which the balanced transmission line is connected becomes 180 degrees. This makes it possible to efficiently cancel noise in the two signal lines of the balanced transmission line connected to the first secondary strip line and the second secondary strip line. Also, it is not required that the design accuracy of the element is so high, and the manufacture of the element becomes easy and the productivity is improved.

Further, when the surface-mount type balanced-unbalanced conversion element of the present invention is used as a balun transformer, an unbalanced transmission line is connected to the first and second primary strip lines, and the first and second secondary striplines are connected. Two signal lines of a balanced transmission line are connected to the next strip line. With this element, a signal on the unbalanced transmission line can be extracted between two signal lines on the balanced transmission line, or a signal between two signal lines on the balanced transmission line can be extracted on the unbalanced transmission line. . Further, in this element, the thickness of the dielectric substrate can be arbitrarily set, and if the thickness is changed, the characteristic impedance changes, so that the degree of freedom of the characteristic impedance is large.

As the dielectric substrate, either resin or ceramics may be used. However, ceramics is preferable because it has a smaller dielectric loss and a larger heat dissipation effect than glass epoxy resin or the like. If a dielectric substrate made of ceramics is used, dielectric loss can be reduced,
The element can be further downsized. In addition, when the strip line and the input / output terminals are formed of a material having high conductivity such as copper or silver, a surface-mount type balanced-unbalanced conversion element with small conversion loss can be obtained. Further, in this element, an input / output terminal serving as an unbalanced terminal, a balanced terminal, and a ground terminal is provided on the surface thereof, so that it can be easily surface-mounted on a printed circuit board or the like.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A surface mount type balanced-unbalanced conversion element according to the second invention will be described in detail below with reference to FIG. 1 schematically showing a longitudinal section thereof and FIG. I do. (1) Manufacture of Surface-Mount Balanced-Unbalanced Conversion Element In this manufacturing method, after firing, a green sheet (dielectric sheet) that constitutes a dielectric layer is denoted by the symbol:
For convenience, the same reference numerals as those of the dielectric layer are used. Also, the same reference numerals are used for the strip line, the via hole portion, and the electromagnetic shielding material layer before and after firing.

A slurry-like glass ceramic raw material was prepared, and green sheets having a thickness of 0.1 mm, 0.2 mm and 0.4 mm were produced by using this raw material by a doctor blade method. First, almost all of the upper surface of a green sheet having a predetermined plane dimension (hereinafter, the plane dimensions of green sheets constituting each dielectric layer are the same) having a thickness of 0.1 mm is commercially available for use in a thick film circuit. Was printed to form a seventh dielectric sheet 37 provided with the second electromagnetic shielding material layer 5b. Thereafter, the silver paste is printed in a spiral shape having a required width and length on the upper surface of a 0.4 mm-thick green sheet provided with a third via hole portion 4c at the center, thereby forming a second secondary strip line. A fifth dielectric sheet 35 provided with 22 was formed. Next, a silver paste was printed on the upper surface of the green sheet having a thickness of 0.1 mm in the same width, length, and shape as above to form a second dielectric sheet 32 provided with the second primary strip lines 21. .

After that, the silver paste is printed on almost the entire upper surface of the green sheet having a thickness of 0.4 mm on which a part of the first via hole 4a is formed, excluding the portion where the first via hole 4a is formed. And the third electromagnetic shielding material layer 5c
To form a dielectric sheet. Next, a thickness of 0.2 m in which a part of the first via hole portion 4a is formed
The first primary strip line 11 and the input / output terminals 8 are printed with silver paste on required portions of the upper surface of the green sheet of m.
A dielectric sheet provided with a line 6 for connecting to a was formed. After that, a part of the first via hole portion 4a and another thickness of 0.2 m where the fourth via hole portion 4d is formed are formed.
The silver paste was printed on the upper surface of the m green sheet in the same width, length and shape as the second primary strip lines 21 and the like to form a dielectric sheet provided with the first primary strip lines 11. The third dielectric sheet 33 is constituted by these dielectric sheets and these.

Next, a silver paste is printed on the upper surface of the green sheet having a thickness of 0.1 mm in the same width, length and shape as described above, and the first dielectric sheet 31 provided with the first secondary strip line 12 is provided. Was formed. Then the second in the center
The silver paste was printed on almost the entire surface of one side of a 0.4 mm-thick green sheet provided with the via hole portion 4b to form a fourth dielectric sheet 34 provided with the first electromagnetic shielding material layer 5a. .

The seventh, fifth, second, third, first, and fourth dielectric sheets formed as described above are laminated in this order, and furthermore, on the fourth dielectric sheet 34, Thickness 0.
After laminating a 1 mm green sheet (sixth dielectric sheet 36), the sheets were integrated by heating and pressing. Thereafter, the integrated laminate is further heated to decompose and remove the binder and the like in the glass ceramic material, and then fired to form input / output terminals 7a, 7b, 8a, 8b, 9a and 9b on the side surfaces. Thus, a surface-mount type balanced-unbalanced conversion element was obtained.

(2) Structure of Surface Mount Type Balance-Unbalance Conversion Element In FIG. 1, the first coupled line body 1 is formed on one surface of a first dielectric layer 31 made of glass ceramic having a thickness of 0.1 mm. It comprises a first primary strip line 11 and a first secondary strip line 12 formed on the other surface. Further, the second coupled line body 2 includes a second primary strip line 21 formed on one surface of a second dielectric layer 32 also made of glass ceramic having a thickness of 0.1 mm and a second primary strip line 21 formed on the other surface. And the secondary strip line 22. Each of these strip lines is formed in a spiral shape having the same shape, and has the same length of １ ／ wavelength.

The first coupled line body 1 and the second coupled line body 2 are laminated on both surfaces of the third dielectric layer 33 so as to face each other. The third dielectric layer 33 is made of a glass ceramic and has a thickness of 0.4 mm and a thickness of 0.4 mm.
It is composed of two dielectric layers of 2 mm. Then, between the dielectric layer having a thickness of 0.4 mm and the dielectric layer having a thickness of 0.2 mm, silver paste is printed as an electromagnetic shielding material to form a third electromagnetic shielding material layer 5c. Further, between the two dielectric layers having a thickness of 0.2 mm, the same silver paste is printed to form connection lines 6. The first primary strip line 11 and the second primary strip line 21 are each formed at a spiral outer end by a first via hole portion 4 a provided through the third dielectric layer 33. They are connected in series. One end of the connection line 6 is connected to the end of the spiral center of the first primary strip line 11 by a via hole 4d, and the other end of the connection line 6 is connected to the input / output terminal 8a. This terminal is an unbalanced terminal.

The spiral outer end of the first secondary strip line 12 is connected to an input / output terminal 7b provided on the outer peripheral surface of the element, and this terminal becomes one of the balanced terminals. Further, a spiral outer end of the second secondary strip line 22 is connected to an input / output terminal 9b provided on the outer peripheral surface of the element, and this terminal becomes another one of the balanced terminals. The end of the center of the second primary strip line 21 is open.

Further, the surface of the first dielectric layer 31 on which the first secondary strip line 12 is formed has a thickness of 0.4 mm.
A fourth dielectric layer 34 made of glass ceramics having a thickness of 2 mm is provided. On the other surface of the fourth dielectric layer 34,
A silver paste is printed as an electromagnetic shielding material, and a first electromagnetic shielding material layer 5a is formed. On the other hand, on the surface of the second dielectric layer 32 on which the second secondary strip line 22 is formed, a fifth dielectric layer 35 made of glass ceramic having a thickness of 0.4 mm is also provided. On the other surface of the fifth dielectric layer 35, a silver paste is printed as an electromagnetic shielding material, and a second electromagnetic shielding material layer 5b is formed. Then, the first secondary strip line 12
Is connected to the first electromagnetic shield material layer 5a by the second via hole 4b, and the end of the spiral center of the second secondary strip line 22 is the same. Is connected to the second electromagnetic shield material layer 5b by the third via hole 4c.

On the surface of the fourth dielectric layer 34 on which the first electromagnetic shielding material layer 5a is formed, a sixth dielectric layer 36 made of glass ceramic having a thickness of 0.1 mm is laminated. Similarly, on the surface of the fifth dielectric layer 35 on which the second electromagnetic shield material layer 5b is formed, a seventh dielectric layer 37 made of glass ceramic having a thickness of 0.1 mm is laminated. The sixth dielectric layer 36 and the seventh dielectric layer 37
Protects the first and second electromagnetic shield material layers 5a and 5b and constitutes the outer surface of the element. Although FIG. 1 is a vertical cross section of the element, two input / output terminals 7a and 7b are shown on both sides, but actually, at equal intervals in the width direction of the element as shown in the perspective view of FIG. And four more input / output terminals 8
a, 8b, 9a and 9b are provided, which are used as a ground terminal, an unbalanced terminal and two balanced terminals.

(3) Performance evaluation of surface-mount type balanced-unbalanced conversion element The above-mentioned surface-mounted balanced-unbalanced conversion element was used, and the unbalanced terminal reflection loss, insertion loss and phase difference were measured under the following conditions. Its performance was evaluated. Table 1 shows the results. Frequency; 310 MHz, 620 MHz and 930 MHz Unbalanced terminal input impedance; 50 Ω Balanced terminal impedance; 100 Ω

[0027]

[Table 1]

According to the results shown in Table 1, the phase difference between the balanced transmission lines tends to become slightly smaller as the frequency increases, but is approximately 180 degrees at any frequency. Therefore, it is presumed that noise in the two signal lines of the balanced transmission circuit is efficiently canceled. Also, even if the frequency is the lowest at 310 MHz,
It can be seen that a surface-mounted balanced-unbalanced conversion element having a very small size of 3.3 × 3.3 × 2.0 mm and excellent performance with little loss is obtained.

[0029]

According to the first and second aspects of the present invention, strip lines used for coupling surface mount type baluns are stacked in the thickness direction of the elements, and are joined and arranged. The device can be more easily miniaturized than a device of the type, and is useful in a communication device such as a portable transceiver. Further, the surface mount type unbalanced conversion element can be used in an impedance conversion circuit having an arbitrary conversion ratio.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a longitudinal section of a surface-mount type balanced-unbalanced conversion element according to a second invention.

FIG. 2 is a perspective view illustrating an appearance of a surface-mount type balanced-unbalanced conversion element according to a second invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; 1st coupling line body, 11; 1st primary stripline, 12; 1st secondary stripline, 2; 2nd coupling line body, 21; 2nd primary stripline, 22; Secondary strip line 3; dielectric substrate 31; first dielectric layer 32; second dielectric layer 33; third dielectric layer 34; fourth dielectric layer 35; fifth dielectric Layer, 36;
Sixth dielectric layer, 37; seventh dielectric layer, 4a; first via hole, 4b; second via hole, 4c; third via hole, 4d; fourth via hole, 5a; first electromagnetic shield material layer 5b; second electromagnetic shield material layer, 5c; third electromagnetic shield material layer, 6; lines connecting first primary strip line 11 and input / output terminal 8a, 7a, 7b, 8
a, 8b, 9a, 9b; input / output terminals.

Claims (5)

[Claims] 1. A first dielectric layer, and (2) a first primary strip line formed on one surface of the first dielectric layer and a first secondary strip line formed on the other surface. And (3) a second dielectric layer, (4)
A second coupling line body comprising a second primary strip line formed on one surface of the second dielectric layer and a second secondary strip line formed on the other surface, A next stripline and the first secondary stripline,
And the second primary strip line and the second secondary strip line are each electromagnetically coupled,
In addition, the first coupled line body and the second coupled line body have a third
A surface-mounted balanced-unbalanced conversion element, which is arranged in a longitudinal direction of the element via a dielectric layer. (1) a first dielectric layer; (2) a first primary strip line formed on one surface of the first dielectric layer and a first secondary strip line formed on the other surface. (3) a fourth dielectric layer in which one surface is laminated on the first secondary strip line and the other surface is provided with a first electromagnetic shielding material layer; A second dielectric layer, (5) a second dielectric layer formed on one surface of the second dielectric layer;
A second coupled line body comprising a next strip line and a second secondary strip line formed on the other surface; and (6)
A fifth dielectric layer having one surface laminated on the second secondary strip line and the other surface provided with a second electromagnetic shielding material layer, wherein the first primary strip line and the first A secondary strip line, and the second primary strip line and the second secondary strip line are electromagnetically coupled to each other, and the first coupled line body and the second coupled line body are connected to each other. A surface-mounted balanced-unbalanced conversion element, wherein the element is arranged via three dielectric layers. 3. The first secondary strip line and the first electromagnetic shield material layer are connected by a second via hole portion, and the second secondary strip line and the second electromagnetic shield material layer are connected to each other. 3. The surface-mounted balun converter according to claim 2, wherein the first and second via holes are connected by a third via hole. 4. The device according to claim 1, wherein the first primary strip line and the second primary strip line are connected by a first via hole. Surface mount type unbalanced conversion element. 5. The first primary strip line, the first secondary strip line, the second primary strip line, and the second secondary strip line are bent or spirally formed. The surface-mounted balun converter according to any one of claims 1 to 4, wherein