JPH05335817A - Directional coupler - Google Patents

Abstract

PURPOSE:To obtain the directional coupler in which the effective length of a coupling line is not fluctuated by ensuring bridge connection by a wire. CONSTITUTION:Plural pairs of strip lines 12, 14, 16, 18 with a prescribed width are formed on a dielectric board 10. A proximity point where ends of a couple of strip lines 12, 14 are close to each other and a proximity point where ends of other couple of strip lines 16, 18 are close to each other are coupled by plural coupling strip lines 22, 24, 26 having a length of 1/4 wavelength with respect to an operating signal, and the coupling strip lines 22, 24, 26 are in bridge connection by wires 28, 29. Notches 16a, 14a are formed to the ends of the strip lines 16, 14 and contain ends 22a, 26a of the coupling strip lines 22, 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional coupler, and more particularly to a distributed coupling type directional coupler in a microstrip line for transmitting microwaves.

[0002]

2. Description of the Related Art Conventionally, as a distributed coupling type directional coupler in a microstrip line, as shown in FIG.
A four-wavelength coupling type directional coupler, a tandem connection type directional coupler shown in FIG. 5 (b), and an interdigitated type directional coupler shown in FIG. 5 (c) are known.

A quarter wavelength coupling type directional coupler is shown in FIG.
As shown in (a), the strip lines 100 and 102 are brought close to each other over a length of ¼ wavelength to be coupled to form a directional coupler. However, in order to achieve a tight coupling degree of about 3 dB by using distributed coupling of microstrip lines on a general printed circuit board such as a Teflon (registered trademark) glass substrate, the spacing between the coupling lines of the strip lines 100 and 102 is large. 0.5
It was necessary to form the film with a thickness of about μm, which was very difficult in terms of manufacturing technology.

In order to solve the problem of such a 1/4 wavelength coupling type directional coupler, the tandem connection type directional coupler shown in FIG. 5 (b) and the interdigitation type shown in FIG. 5 (c). Tate directional couplers have been proposed. The tandem connection type directional coupler forms strip lines 104, 106, 108 and 110 as shown in FIG. 5B, and connects the strip line 104 and the strip line 108 to the wire 11.
Bridge connection by 2 (connection by aerial cross wiring),
By bridging the strip line 106 and the strip line 110 with the wire 114, 8.43
By connecting directional couplers of dB in two stages, a coupling degree of 3 dB is realized. In the interdigitated directional coupler, as shown in FIG. 5C, the proximity points where the ends of the strip lines 120 and 122 are close to each other and the ends of the strip lines 124 and 126 are close to each other. The coupling line 130 that couples the adjacent points is divided into a plurality of coupling strip lines 132, 134, 136, and the coupling strip lines 132, 136 are bridge-connected by the wires 140, 142 to increase the number of distributed couplings. By doing so, the degree of coupling is increased.

[0005]

However, in any case, as shown in FIGS. 5 (b) and 5 (c), the strip line of the coupling portion has a width as narrow as possible in order to have an inductance component, Since it is electromagnetically coupled, it is desirable that the gap between the strip lines is as narrow as possible. With the current processing accuracy of the conductor pattern, the width of the strip line is 2
Generally, the gap between strip lines is about 10 μm at 0 μm. It is necessary to connect such extremely thin strip lines with each other by using a gold wire having a diameter of 20 to 30 μm, which is thicker than the width of the strip lines, and by bonding by heat and pressure.

Therefore, there is a problem that adjacent strip lines for coupling are short-circuited at the time of wire bonding, or a connection failure such that the strip line and the gold wire are not completely connected by wire bonding is likely to occur. Further, since the effective length of the coupling line is determined by the bonding position of the gold wire, there is a problem that the length of the coupling line fluctuates.

An object of the present invention is to provide a directional coupler which can surely make a bridge connection by wires and which does not change the effective length of the coupled line.

[0008]

The above object is to provide a plurality of pairs of strip lines having a predetermined width on a dielectric substrate, and a first proximity point where ends of the pair of strip lines are adjacent to each other. A second proximity point where the ends of the pair of strip lines are close to each other is coupled by a plurality of coupling strip lines each having a length of about ¼ wavelength of the used signal, and at least one end of the coupling strip line is coupled. In a directional coupler in which the wire and the vicinity of the first or second proximity point are bridge-connected by a wire, a coupling strip in which the wire is connected near the first or second proximity point of the strip line This is achieved by a directional coupler characterized in that a notch is formed to accommodate the end of the line.

Further, it is desirable to widen the width of the end portion of the coupling strip line housed in the cutout portion of the strip line.

[0010]

According to the present invention, since the notch is formed at the end of the input / output strip line and the end of the coupling strip line to which the wire is connected is accommodated in the notch, It is possible to surely perform the bridge connection by the wire and to keep the effective length of the coupled line constant.

Further, if the width of the end portion of the coupling strip line accommodated in the cutout portion of the input / output strip line is widened, the wire bonding can be performed more reliably.

[0012]

1 shows a directional coupler according to a first embodiment of the present invention. Strip lines 12, 14, 16 and 1 for signal input / output are provided on the front surface of the dielectric substrate 10 whose back surface is grounded.
8 is formed. Strip lines 12, 14, 1
6 and 18 are formed to have a constant impedance of 50Ω at high frequency. That is, if the thickness of the dielectric substrate 10 is d and the dielectric constant is ε, the strip lines 12, 14,
The width W of 16 and 18 is determined by the following equation W = (d × 2.7) / (ε) ^1/2 . For example, as the dielectric substrate 10, 0.
If a 38 mm thick alumina substrate (dielectric constant ε = 10) is used, the width W is 0.36 mm.

Strip line 12 and strip line 14
Of the strip line 16 and the end portions of the strip line 18 are arranged to be close to each other. The proximity point where the ends of the strip lines 12 and 14 are close to each other and the proximity point where the ends of the strip lines 16 and 18 are close to each other are the effective wavelength λ of the microwave used.
Are coupled by a coupling line 20 having a length of 1/4.

In this embodiment, the coupling line 20 is composed of three coupling strip lines 22, 24 and 26. The coupling strip lines 22, 24, 26 have a width of 20.
.mu.m, and are formed at a distance of 20 .mu.m from each other. The widths and intervals of the coupling strip lines 22, 24 and 26 are determined by the required degree of coupling of the directional coupler. In addition to the width and spacing described above, the width is 20 μm and the spacing is 10 μm, the width is 10 μm and the spacing is 10 μm, and the width is 3
A combination of 0 μm and an interval of 10 μm can be considered.

In FIG. 1, the central coupling strip line 24 has its upper end continuing to the end of the strip line 14 and its lower end continuing to the end of the strip line 16. The left side of the coupling strip line 22 is continuous with the end of the strip line 12, and the lower end is 50 μm.
And a wide pad portion 22a are provided. A notch 16a having a length of 60 μm and a width of 90 μm is formed at an end of the strip line 16 facing the coupling strip line 22, and a pad portion 22a of the coupling strip line 22 is formed.
Is stored. The pad portion 22a of the coupling strip line 22 and the end of the strip line 18 are bridge-connected to each other by a wire 29 made of gold or the like across the coupling strip line 24.

A lower end of the coupling strip line 26 on the right side is continuous with the end of the strip line 18, and a pad portion 26a having a width as wide as 50 μm is provided at the upper end. At the end of the strip line 14, a coupling strip line 26 is provided.
A notch portion 14a having a length of 60 μm and a width of 90 μm is formed in a portion facing to, and the pad portion 26a of the coupling strip line 26 is housed. Strip line for coupling 26
The pad portion 26a and the end portion of the strip line 12 are bridge-connected by a wire 28 made of gold or the like across the coupling strip line 24.

The size of the pad portions 22a and 26a of the coupling strip lines 22 and 26 is the same as that of the wire 2 to be used.
When gold wires are used as the wires 28, 29, the size of the pad portions 22a, 26a is 1.5 to 2 times or more the diameter of the wires 28, 29 or more.
It is preferably 0 times or less. For example, when a gold wire having a diameter of 25 μm is used, it is necessary to have a good knowledge of bonding if the pad portion 2 is used.
The size of 2a and 26a is at least 50 μm in height and 50 μ in width.
m is enough.

As described above, according to this embodiment, since the pad portion is provided at the end of the coupling strip line, the bridge connection by the wire can be easily performed. Moreover, since the notch is provided at the end of the strip line and the pad is housed in the notch, the effective length of the coupling strip line does not change and affects the characteristics of the directional coupler. Never.

Next, FIG. 2 shows a directional coupler according to a second embodiment of the present invention. The same components as those of the directional coupler shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the end portions of the coupling strip lines 22 and 26 are extended without changing the width and are accommodated in the cutout portions 14a and 16a of the strip lines 14 and 16, respectively. The distance between the ends of the coupling strip lines 22 and 26 and the edges of the notches 14a and 16a is made larger than the width of the coupling strip lines 22 and 26.

For example, strip lines 12, 14, 1
The width W of 6 and 18 is 0.4 mm, the strip lines for coupling 22, 24 and 26 are formed with a width of 20 μm and an interval of 10 μm, and the cutouts 14a and 16a are 100 μm in length and 20 in width.
When formed in μm, the strip lines for coupling 22 and 26
D1 between the tip of the and the edges of the notches 16a and 14a
= 21 μm and d2 = 50 μm.

In this embodiment, the coupling strip line 22,
Although the pad portion is not provided at the end portion of 26, when connecting to the end portion of the coupling strip lines 22 and 26 by the wires 28 and 29 such as gold, bonding to the center of the cutout portions 16a and 14a. Wires 28 and 29
The tip of the cable collapses and the shape changes, and the strip line for coupling 2
The ends of 2, 26 are contacted and securely connected.

As described above, according to this embodiment, it is possible to easily perform the bridge connection by the wire without providing the pad portion at the end portion of the coupling strip line. Third of the present invention
FIG. 3 shows a directional coupler according to the embodiment of FIG. Thickness 0.3
Strip lines 32, 3 having a width of 0.40 mm for signal input / output are provided on a dielectric substrate 30 made of an 8 mm alumina substrate.
4, 36, 38 are formed. Stripline 38
The input / output terminal side of is terminated by a 50Ω termination section 39.

The proximity point where the ends of the strip lines 32 and 34 are close to each other and the proximity point where the ends of the strip lines 36 and 38 are close to each other are 1 of the effective wavelength λ of the microwave used.
They are coupled by a coupling line 40 having a length of / 4. In this embodiment, the coupling line 40 is composed of four coupling strip lines 42, 43, 44 and 45. The coupling strip lines 42, 43, 44, 45 have a thickness of 60 μ.
m, the width is 20 μm, and they are formed at intervals of 10 μm.

In FIG. 3, the leftmost coupling strip line 42 has its upper end connected to the end of the strip line 32, and its lower end is provided with a pad portion 42a of 50 μm in length and 50 μm in width. At the end of the strip line 36, a length of 60 μm is provided at a portion facing the coupling strip line 42.
A cutout portion 36a having a width of m and a width of 60 μm is formed, and the pad portion 42a of the coupling strip line 42 is housed therein. The pad portion 42a of the coupling strip line 42 and the end of the strip line 38 are bridge-connected by a wire 50 made of gold or the like across the coupling strip lines 43, 44, 45.

The coupling strip line 43 on the right side of the coupling strip line 42 has its upper end continuing to the end of the strip line 34 and its lower end continuing to the end of the strip line 36. The lower end of the coupling strip line 44 on the right side of the coupling strip line 43 is continuous with the end of the strip line 38, and the upper end is 50 μm long and 50 μm wide.
Pad portion 46a is provided. Strip line 3
A cutout portion 34a having a length of 60 .mu.m and a width of 60 .mu.m is formed at the end of 4 at a portion facing the coupling strip line 44, and the pad portion 44a of the coupling strip line 44 is accommodated therein. The pad portion 44 of the coupling strip line 44
a is a wire 52 such as gold.
Is connected in a bridge across the coupling strip lines 42 and 43.

The rightmost coupling strip line 45 is
The upper end is continuous with the end of the strip line 34, and the lower end is provided with a pad portion 45a having a length of 50 μm and a width of 50 μm. The end portion of the strip line 38 has a length of 60 μm and a width of 60 μm at a portion facing the coupling strip line 45.
Is formed, and the pad portion 45a of the coupling strip line 45 is housed therein. The pad portion 45a of the coupling strip line 45 and the end of the strip line 36 are bridge-connected to each other by a wire 54 made of gold or the like across the coupling strip line 44.

As described above, according to this embodiment, since the pad portion is provided at the end portion of the coupling strip line, the bridge connection by the wire can be easily performed, and the cut portion is provided at the end portion of the strip line. Since the notch is provided and the pad is accommodated in the notch, the effective length of the coupling strip line does not change and the characteristics of the directional coupler are not significantly affected.

A directional coupler according to a fourth embodiment of the present invention is shown in FIG. The same components as those of the directional coupler shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, of the signal input / output strip lines 32, 34, 36, 38 formed on the dielectric substrate 30, the input / output terminal side of the strip line 36 is terminated by a 50Ω termination portion 37.

The connection between the adjacent points where the ends of the strip lines 32 and 34 are close to each other and the adjacent points where the ends of the strip lines 36 and 38 are close to each other is 1/4 of the effective wavelength λ of the microwave used. They are coupled by a length coupling line 60. In this embodiment, the coupling line 60 is composed of six coupling strip lines 61, 62, 63, 64, 65, 66. Coupling strip lines 61, 62, 6
3, 64, 65, 66 have a thickness of 60 μm and a width of 20 μ
m are formed at a distance of 10 μm from each other.

In FIG. 4, the leftmost coupling strip line 61 has a length of ⅛ of the effective wavelength λ of the microwave used, the lower end is continuous with the end of the strip line 36, and the upper end is Is a pad portion 6 having a length of 50 μm and a width of 50 μm
1a is provided. The coupling strip line 62 on the right side of the coupling strip line 61 has a length of ¼ of the effective wavelength λ of the microwave used, the upper end is continuous with the end of the strip line 32, and the lower end is vertically. 50 μm, width 5
A pad portion 62a of 0 μm is provided. At the end of the strip line 36, a notch 36a having a length of 60 μm and a width of 60 μm is formed in a portion facing the coupling strip line 62, and the pad portion 62a of the coupling strip line 62 is formed.
Is stored. The pad portion 62a of the coupling strip line 62 and the end of the strip line 38 are bridge-connected to each other by a wire 70 made of gold or the like across the coupling strip line 63.

The coupling strip line 63 on the right side of the coupling strip line 62 has a length of ⅛ of the effective wavelength λ of the microwave used, the lower end is continuous with the end of the strip line 36, and the upper end. Is provided with a pad portion 63a having a length of 50 μm and a width of 50 μm. The pad portion 61a of the coupling strip line 61 and the pad portion 63a of the coupling strip line 63 are bridge-connected by a wire 72 across the coupling strip line 62.

The coupling strip line 64 on the upper side of the coupling strip line 63 has a length which is ⅛ of the effective wavelength λ of the microwave used, and is 50 μm in length and 50 μm in width at the upper and lower ends.
Pad portions 64a and 64b are provided. At the end of the strip line 32, a notch portion 32a having a length of 60 μm and a width of 60 μm is provided in a portion facing the coupling strip line 64.
Is formed and the pad portion 64 of the coupling strip line 64 is formed.
a is stored. The pad portion 64a of the coupling strip line 64 and the end portion of the strip line 34 are connected to the wire 74.
Are bridge-connected across the coupling strip line 65.

The upper end of the coupling strip line 65 on the right side of the coupling strip lines 63 and 64 is the strip line 3
2 and the lower end is continuous with the end of the strip line 38. The rightmost coupling strip line 66 has a length of ⅛ of the effective wavelength λ of the microwave used, the upper end is continuous with the end of the strip line 34, and the lower end has a length of 50 μm and a width of 50 μm. Pad portion 66a
Is provided. The pad portion 64b at the lower end of the coupling strip line 64 and the pad portion 66a of the coupling strip line 66 are connected by a wire 76 to the coupling strip line 65.
Bridged across.

As described above, according to this embodiment, since the pad portion is provided at the end of the coupling strip line, the bridge connection by the wire can be easily performed, and the tight coupling degree of the coupling line can be increased. .. The present invention is not limited to the above embodiment, and various modifications can be made. For example, the mode of the coupling line is not limited to that described in the above embodiment, and the number of coupling strip lines to be divided may be increased or decreased,
Other coupling modes such as an interdigitated directional coupler or a tandem connection type directional coupler may be used.

[0035]

As described above, according to the present invention, the notch is formed at the end of the strip line, and the end of the coupling strip line to which the wire is connected is housed in the notch. Therefore, it is possible to prevent short-circuits between the coupled lines, peeling of the bonding, and the like, to reliably perform the bridge connection by the wires, and to keep the effective length of the coupled lines constant.

[Brief description of drawings]

FIG. 1 is a diagram showing a directional coupler according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a directional coupler according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a directional coupler according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a directional coupler according to a fourth embodiment of the present invention.

FIG. 5 is a diagram showing a conventional directional coupler.

[Explanation of symbols]

10 ... Dielectric substrate 12, 14, 16, 18 ... Strip line 14a, 16a ... Notch part 20 ... Coupling line 22, 24, 26 ... Coupling strip line 22a, 26a ... Pad part 28, 29 ... Wire 30 ... Dielectric Body substrate 32, 34, 36, 38 ... Strip line 34a, 36a, 38a ... Notch part 37, 39 ... 50Ω termination part 40 ... Coupling line 42, 43, 44, 45 ... Coupling strip line 42a, 44a, 45a ... Pad portion 50, 52, 54 ... Wire 60 ... Coupling line 61, 62, 63, 64, 65, 66 ... Coupling strip line 61a, 62a, 63a, 64a, 64b, 66a ... Pad portion 70, 72, 74, 76 ... Wires 100, 102 ... Strip lines 104, 106, 108, 110 ... Strip lines 112, 114 ... Y 120, 122, 124, 126 ... stripline 130 ... coupling line 132, 134, 136 ... coupling strip lines 140, 142 ... wire

Claims (2)

[Claims] 1. A plurality of pairs of strip lines having a predetermined width are formed on a dielectric substrate, and a first proximity point where ends of a pair of strip lines are close to each other and ends of another pair of strip lines are adjacent to each other. The second proximity point where is close to is about 1 of the used signal
/ 4 wavelengths are coupled by a plurality of coupling strip lines, and an end of at least one coupling strip line and the vicinity of the first or second proximity point are bridge-connected by a wire. In the sex coupler, near the first or second neighbor point of the strip line,
A directional coupler, wherein a cutout portion is formed to accommodate an end portion of the coupling strip line to which the wire is connected. 2. The directional coupler according to claim 1, wherein a width of an end portion of the coupling strip line accommodated in the cutout portion is widened.