JPH04271602A - Directional coupler - Google Patents

Abstract

PURPOSE:To realize the directional coupler with a smaller size than that of a conventional directional coupler. CONSTITUTION:Green sheets with strip line 28, 32, 36, 40 are laminated while sandwiching with a green sheet 14 inbetween respectively, baked to manufacture a lamination unit 12. Then an external electrode is used to interconnect strip lines 42, 38, strip lines 30, 34, strip line 42, 34 and strip lines 30, 38 respectively. Moreover, each connection electrode of the laminated green sheets 14 with shield electrode is interconnected respectively by the external electrode. Thus, the strip lines 30, 34, 38 and 42 form respectively branch lines and the directional coupler is formed in the lamination unit.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention relates to a directional coupler.
In particular, 3dB couplers and 90° for phase modulation and phase detection in transmitting and receiving terminals of digital mobile radio communications, for example.
It relates to directional couplers used in phase converters and the like.

0002

2. Description of the Related Art As a conventional directional coupler, there is, for example, a branch line type directional coupler 1 as shown in FIG. This is a microstrip line formed on one plane. In this conventional branch line type directional coupler 1, the branch lines 2, 3, 4, and 5 are formed to have a length of λ/4 and are connected so as to form a square shape as a whole. And brunch line 2
An input (output) end 6 is formed at the connection portion of the branch lines 3 and 4, and an input (output) end 6' is formed at the connection portion of the branch lines 3 and 4, respectively. Further, an output (input) end 7 is formed at the connection portion between the branch lines 2 and 5, and an output (input) end 7' is formed at the connection portion between the branch lines 3 and 5, respectively.

In such a branch line type directional coupler 1, the microwave input from the input (output) end 6 or 6' passes through the λ/4 branch line 4 or 5 and is output. The signals are outputted from the (input) input ends 7 and 7' with a phase difference of 90° from each other.

0004

However, the conventional branch line type directional coupler 1 requires a large mounting area. For example, if the operating frequency is 900 MHz, one piece of the branch line will be approximately 83 mm (however, the relative dielectric constant εr is assumed to be 1). Therefore, the conventional branch line type directional coupler is not suitable for applications such as mobile wireless terminals, which require miniaturization.

[0005] Therefore, the main object of the present invention is to provide a directional coupler that requires a small mounting area.

[0006]

[Means for Solving the Problems] The present invention comprises laminating at least two ceramic sheets each having at least one strip line formed on one main surface, interposing a shield electrode layer therebetween, and further providing a strip line. This is a directional coupler in which lines are connected with external electrodes.

[0007]

By interconnecting each stripline with external electrodes, each stripline functions as a branchline.

[0008]

According to the present invention, a directional coupler with a small mounting area can be obtained by stacking strip lines to form a branch line. Therefore, it is possible to downsize mobile radio terminals and the like that utilize it. The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a directional coupler 10 of this embodiment includes a laminated unit 12 formed by laminating ten ceramic green sheets as shown in FIG. To manufacture the laminated unit 12, first, the green sheet 14 with shield electrodes is prepared. The green sheet with shield electrode 14 includes a ceramic green sheet 16 and a shield electrode 18 formed on the upper surface of the ceramic green sheet 16 at a constant distance from the edge. Connection electrodes 20 and 22 are formed on one long side of the shield electrode 18 at a predetermined interval approximately in the center thereof. Similarly, connection electrodes 24 and 26 are formed on the other long side at a predetermined interval approximately in the center thereof. Each of the connection electrodes 20 to 26 is formed to protrude from the shield electrode 18 in the short side direction of the ceramic green sheet 16,
The tip thereof is flush with the long side surface of the ceramic green sheet 16. Note that the material constituting the ceramic green sheet 16 is, for example, BaO-S.
Examples include those consisting of iO2 -Al2O3 -B2O3 + additives. Further, the shield electrode 18, the connection electrodes 20 to 26, and each strip line to be described later are formed by printing an electrode paste made of, for example, Cu on the ceramic green sheet 16.

[0010] The green sheet 14 with shield electrode includes:
Green sheets 28 with strip lines are overlapped. The green sheet 28 with strip lines includes the ceramic green sheet 16 and the ceramic green sheet 1.
6 includes a strip line 30 formed on the top surface of the 6. The strip line 30 is formed in a meandering manner to make the whole compact, and its length is basically 1/4 (λ/4) of the wavelength λ of the microwave used, but in this case, It is preferable to set it in consideration of the length of the side electrode. And the left end is the ceramic green sheet 16
The ceramic green sheet 16 is disposed near the short side of the ceramic green sheet 16 at a predetermined distance from the short side thereof, and its tip is flush with the surface of the long left side of the ceramic green sheet 16 . Further, the right end of the strip line 30 is arranged at a predetermined distance from the front short side of the ceramic green sheet 16, and its tip is flush with the surface of the right long side of the ceramic green sheet 16.

[0011] This green sheet with strip line 2
8 is overlaid with a green sheet 14 with a shield electrode. Then, the green sheet 32 with strip lines is superimposed on the green sheet 14 with shield electrodes. The green sheet with strip lines 32 includes the ceramic green sheet 16 and the strip lines 34 formed on the top surface of the ceramic green sheet 16. The stripline 34 is thinner than the stripline 30, meandering, and has a length of approximately λ/4.
It is formed as follows. And strip line 3
The left end of the ceramic green sheet 16 is placed near the front short side of the ceramic green sheet 16 at a predetermined distance from the short side, and its tip is flush with the surface of the left long side of the ceramic green sheet 16. There is. Also, strip line 38
The right end of the ceramic green sheet 16 is placed near the short side on the back side at a predetermined distance from the short side, and its tip is flush with the surface of the right long side of the ceramic green sheet 16. .

[0012] This green sheet with strip line 3
A green sheet 14 with a shield electrode is superimposed on the green sheet 2 . Then, the green sheet 36 with strip lines is placed on top of the green sheet 14 with shield electrodes. The green sheet with strip lines 36 includes the ceramic green sheet 16 and strip lines 38 formed on the upper surface thereof. The strip line 38 is formed in a meandering manner and has the same thickness as the strip line 34, and its length is basically λ/4, but is determined by taking into account the length of the side electrodes. The left end of the strip line 38 is placed near the back short side of the ceramic green sheet 16 at a predetermined distance from the short side, and its tip is flush with the surface of the left long side of the ceramic green sheet 16. It has become. Further, the right end of the strip line 38 is placed near the short side of the ceramic green sheet 16 on the near side at a predetermined distance from the short side, and its tip is flush with the surface of the right long side of the ceramic green sheet 16. It is one.

[0013] This green sheet with strip line 3
A green sheet 14 with a shield electrode is superimposed on the green sheet 6 . Then, the green sheet 40 with strip lines is superimposed on this green sheet 14 with shield electrodes. The green sheet with strip lines 40 includes a ceramic green sheet 16 and strip lines 42 formed on the upper surface thereof. The strip line 42 is formed in a meandering manner and has the same thickness as the strip line 30, and its length is basically λ/4, but is determined by taking into consideration the length of the side electrodes. The left end of the strip line 42 is placed near the back short side of the ceramic green sheet 16 at a predetermined distance from the short side, and its tip is flush with the surface of the left long side of the ceramic green sheet 16. It is one. Moreover, the right end of the strip line 42 is
It is arranged near the short side on the back side of the ceramic green sheet 16 at a predetermined distance from the short side, and its tip is flush with the surface of the long side on the right side of the ceramic green sheet 16 .

[0014] This green sheet with strip line 4
A green sheet 14 with a shield electrode is placed on top of the green sheet 14. Then, the ceramic green sheet 16 is stacked on the shield electrode-equipped green sheet 14 and pressed against it to form a ceramic green sheet laminated unit. When the ceramic green sheet laminated unit is fired, Figure 1
The laminated unit 12 shown in FIG.

The reason why each of the strip lines 30, 34, 38 and 42 formed in the laminated unit 12 is formed in a meandering manner is that the distance of the strip line is λ/4 relative to the operating frequency. This is to reduce the required mounting area of the strip line. However, in this case, care must be taken not to perform resistance treatment or to make the distance between adjacent striplines too small so as not to disturb the characteristic impedance of the stripline. Further, the reason why the strip lines 34 and 38 are formed thinner than the strip lines 30 and 42 is for impedance matching when each strip line functions as a branch line.

On the long side of the laminated unit 12 after firing,
As shown in FIG. 1, external electrodes are formed corresponding to the positions of each connection electrode in the stacked unit 12, for example, by applying electrode material. The external electrode is formed in a U-shape so as to cover a portion of the long side surface, a portion of the top surface, and a portion of the bottom surface of the laminated unit 12. The external electrode 4 is located at the position corresponding to the connection electrode 20 of the green sheet with shield electrode 14.
4, an external electrode 46 is formed at a position corresponding to the connection electrode 22, an external electrode 48 is formed at a position corresponding to the connection electrode 24, and an external electrode 50 is formed at a position corresponding to the connection electrode 26.

Furthermore, an external electrode 52 is formed at a position corresponding to the left end of the strip line 42 and the left end of the strip line 38. An external electrode 54 is formed at a position corresponding to the left end of the strip line 30 and the left end of the strip line 34. Further, an external electrode 56 is formed at a position corresponding to the right end of the strip line 42 and the right end of the strip line 34. An external electrode 58 is formed at a position corresponding to the right end of the strip line 30 and the right end of the strip line 38.

In the directional coupler 10, the external electrode 5
2 by stripline 42 and stripline 3
8 is connected. Further, the strip line 30 and the strip line 34 are connected by the external electrode 54. Then, the strip line 42 is connected by the external electrode 56.
and the strip line 34 are connected. Further, the strip line 30 and the strip line 38 are connected by the external electrode 58. This forms a branch type directional coupler. The strip line 42 corresponds to the branch line 2 shown in FIG.
corresponds to branch line 3 shown in FIG. The strip line 38 corresponds to the branch line 4 shown in FIG. 3, and the strip line 34 corresponds to the branch line 5 shown in FIG.

The directional coupler 10 of this embodiment is actually 9
When used as a 0° phase converter, the external electrode 44
For example, with the external electrode 58 connected to the ground,
Ω and input a sine wave of the target frequency to the external electrode 52, the output waveform of the external electrode 54 will be the same as that of the external electrode 56.
The output waveform is always delayed by 90 degrees in phase.

In the directional coupler of this embodiment, the branch line is divided into four layers of strip lines and stacked, but a two-layer structure including two sides of the branch line in one layer may also be used. Furthermore, when each stripline is to be doubled in length, green sheets with the same stripline may be stacked on top of each other. However, even in this case, it is necessary to sandwich a green sheet with a shield electrode between them. Note that if the above-mentioned 50Ω terminating resistor is formed as a chip resistor or a printed resistor on the top of the laminated unit 12, the mounting area of the directional coupler 10 can be further reduced.

In the directional coupler 10 of this embodiment, since each strip line is sandwiched between shield electrodes and stacked, it is less susceptible to the influence of external interference waves. Further, since the external electrodes are formed on the long sides of the laminated unit 12 and serve as side electrodes, the directional coupler 10 has excellent high frequency characteristics.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an example of the configuration of a stacked unit of the directional coupler shown in FIG. 1;

FIG. 3 is an illustrative diagram showing a conventional branch line type directional coupler.

[Explanation of symbols]

10...Directional coupler 12
...Laminated unit 14
... Green sheet with shield electrode 16 ... Ceramic green sheet 18
...shield electrodes 20, 22, 24, 26
... Connection electrodes 30, 34, 38, 42 ... Strip lines 44, 46, 48, 50, 52, 54, 56,
58...External electrode

Claims (1)

[Claims] Claim 1: At least two ceramic sheets each having at least one stripline formed on one main surface are laminated, a shield electrode layer is interposed between them, and the stripline is connected by an external electrode. , directional coupler.