JP3351366B2 - High frequency transmission line and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention mainly relates to 10 to 15
Several GHz in microwave and millimeter wave bands of 0 GHz
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency transmission line capable of optimizing transmission characteristics in a moderate bandwidth and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a partially cutaway perspective view schematically showing a structure of a conventional high-frequency transmission line as described in Japanese Patent Application Laid-Open Publication No. H10-209,004. This high-frequency transmission line comprises a grounded coplanar line 2 and a signal line 3
Are electrically coupled to each other. The grounded coplanar line 2 includes a signal line 2-1 formed on one surface of the dielectric substrate 1 and one of the two sides at a predetermined distance from the signal line and along the signal line 2-1. It has a first ground plane 2-2 formed on the surface, and a second ground plane 2-3 formed on the other surface of the dielectric substrate 1. On the other hand, the signal line 3 includes a signal line 3-1 formed on the other surface while being electrically insulated from the second ground plane 2-3, and a second ground plane 2
And a ground line 3-2 formed on both sides thereof along the signal line 3-1. In order to electrically connect the grounded coplanar line 2 and the signal line 3, a via 4 is provided between one end of one signal line 2-1 and one end of the other signal line 3-1 opposed thereto. Connected to the first ground plane 2-2 and the second ground plane 2-2.
Are connected by a plurality of ground vias 5.

When the grounded coplanar line 2 is connected to an IC chip, the line width of the signal line 2-1 can be adapted to the line width of the IC chip by employing such a structure of the high-frequency transmission line. Thus, the high-frequency mismatch between the grounded coplanar line 2 and the connection between the IC chip and the IC chip is eliminated, so that the loss can be reduced and the standing wave ratio can be reduced. Further, by using a plurality of ground vias 5 for connection between the first and second ground planes 2-2 and 2-3 of the grounded coplanar line 2, and using a coaxial structure via as necessary, High-frequency mismatch can be reduced and isolation can be increased.

As described above, it is presumed that the transmission characteristics of the high-frequency line shown in FIG. 7, that is, the insertion loss and the reflection loss, are improved.
It is difficult to secure a sufficient area width in a microwave band or a millimeter wave band of 0 GHz or more, and its insertion loss is limited to about -3 dB.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above problems, and has as its object to provide a high-frequency line having good transmission characteristics in a used frequency band and a method of manufacturing the same. .

[0006]

In order to achieve the above object, the inventions described in claims 1 and 2 of the present application are directed to a center line of a signal line of a grounded coplanar line and the center line thereof. The distance between the edge of the ground via closest to
(Μm), when the relative permittivity of the dielectric substrate is εr, and the frequency used is F (GHz), the distance L is F = M ₀ + M ₁ L, where M ₀ = 188−6.0 · εr M Provided is a high-frequency transmission line characterized by being within ± 5% around a value satisfying ₁ = −0.18 + 0.005 · εr.

According to another aspect of the present invention, a conductor pattern forming a grounded coplanar line is formed on two opposing main surfaces of a dielectric substrate. Forming a via for electrically connecting the signal lines of the grounded coplanar line, and a ground via for electrically connecting between ground planes formed on the opposing main surfaces. Wherein the distance between the center line of the signal line and the ground via end closest to the center line is L (μm),
The relative permittivity of the dielectric substrate is εr, and the operating frequency is F (G
Hz), the distance L is F = M ₀ + M ₁ L where M ₀ = 188−6.0 · εr M ₁ = −0.18 + 0.005 · εr ± 5% centered on a value satisfying And a step of manufacturing the high-frequency transmission line.

[0008]

The distance between the center line of the signal line and the end of the ground via closest to the center line is L (μm), the relative permittivity of the dielectric substrate is εr, and the frequency used is F (GHz). When the distance L is within a range of ± 5% around a value satisfying F = M ₀ + M ₁ L, where M ₀ = 188−6.0 · εr M ₁ = −0.18 + 0.005 · εr Are provided with ground vias. This optimizes the transmission characteristics of the high-frequency transmission line in a given frequency band.

[0009]

FIG. 1 is a front view of one embodiment of a high-frequency transmission line according to the present invention, and FIG.
Is a cross-sectional view of the grounded coplanar line of FIG. 1 along the center line AA ′ of the signal line, and FIG. 3 is a cross-sectional view of FIG. 1 along the line BB ′. 1 to 3, the same or similar components as those in FIG. 7 are denoted by the same reference numerals.

1 to 3, a high-frequency transmission line according to the present invention is a first grounded coplanar line having a signal line formed along the center line of one main surface of a dielectric substrate 1. 10 and the other main surface of the dielectric substrate 1 (that is,
A second grounded coplanar line 2 having a signal line formed along the center line of a main surface facing one main surface)
0 is electrically coupled.

As clearly shown in FIG. 1, the signal line 11 of the first grounded coplanar line 10 and the signal line 21 of the second grounded coplanar line 20 are formed such that their center lines coincide with each other. Is done. Further, the first grounded coplanar line 10 includes first ground planes 1 formed on both sides of the signal line 11 and separated by a predetermined distance.
2 and the signal line 11 and the first
And a second ground plane 13 formed on almost the entire surface so as to face the ground plane 12. Similarly, the second grounded coplanar line 20 includes a third ground plane 22 formed on both sides of the signal line 21 and separated by a predetermined distance, and a signal line on one main surface of the dielectric substrate 1. 21 and a fourth ground plane 23 formed substantially on the entire surface in opposition to the third ground plane 22.

Actually, as shown in FIG. 1, the first ground plane 12 and the fourth ground plane 23 are formed on the one main surface so as to be electrically and mechanically continuous. Similarly, the second ground plane 13 and the third ground plane 22 are formed on the other main surface so as to be electrically and mechanically continuous.

Further, as shown in FIGS. 1 and 2, the end of the signal line 11 of the first grounded coplanar line 10 and the end of the signal line 21 of the second grounded coplanar line 20 are different from each other. They are formed so as to overlap, and are electrically connected by vias 4 between these overlapping ends. In addition, between the ground planes 12 and 23 formed on one main surface of the dielectric substrate 1 and the ground planes 13 and 22 formed on the other main surface are on both sides of the center line of the signal lines 11 and 21. The columns are electrically connected by a plurality of ground vias 5 arranged in a straight line and at equal distances from the center lines of the signal lines 11 and 21. In addition, the mutual spacing of the ground vias 5 arranged on each side with respect to the center line of the signal lines 11 and 21 may be arbitrary, but is preferably equal.

According to the present invention, the ground planes 12, 23 are provided.
By changing the distance between the signal lines 11 and 21 and the plurality of vias 5 electrically connecting the ground planes 13 and 22, it is possible to adjust the frequency band in which the insertion loss becomes the best. It has been proposed based on the knowledge that it will be. Based on this finding, the inventor of the present invention has determined that the center lines of the signal lines 11 and 21 and the ends of the ground vias 5 arranged on one side and the other side of the center lines, which are closest to the center line, Is L (μm), the dielectric substrate 1
Is the relative dielectric constant of εr and the frequency at which the insertion loss is the best is F (GHz),

F = M ₀ + M ₁ L (1) However, it has been found that M ₀ = 188−6.0 εr and M ₁ = 0.18 + 0.005 εr are satisfied. If this equation (1) is used, when the operating frequency F and the relative permittivity εr of the dielectric substrate are known, L satisfying the equation (1) is obtained, and ±
If the ground via 5 is placed at a position of 5%, it is about ±
Good insertion loss can be obtained with an error of about 5 GHz.

For example, if the operating frequency band is 60 GHz ± 1
When L is obtained from Expression (1) in the case of using a dielectric substrate having a relative dielectric constant εr of 7.5 at GHz, L is about 58
0 μm. Therefore, L = 580 (μm) and FIG.
3 were manufactured and transmission characteristics thereof were determined. As a result, frequency characteristics of insertion loss as shown in FIG. 4 were obtained.

Next, the frequency band used is also 60 GHz.
When a dielectric substrate having a relative permittivity εr of 7.5 at ± 1 GHz was used, the insertion loss frequency characteristics of the high-frequency transmission line with L = 550 μm and the high-frequency transmission line with L = 610 μm were determined. Was obtained. FIG.
In a, L is L = 580 μm, and b is L = 550 μm
Where c is the characteristic when L = 610 μm. From the graph of FIG. 5, when L is changed by ± 5%, the center frequency becomes ± 5%.
It can be seen that the insertion loss in the used frequency band of 60 ± 1 GHz shows a good value of −1.0 dB or less even if it changes by about GHz and L changes by ± 5%.

Further, the operating frequency band is 60 GHz ± 1 G
In the case of a high-frequency transmission line using a dielectric substrate having a relative permittivity εr of 9.3 at 9.3 Hz, when L is obtained from Expression (1), L
Is about 540 μm. When the transmission characteristics of the high-frequency transmission line were determined, the insertion loss frequency characteristics as shown in FIG. 6 were obtained.

The graphs of FIGS. 4 to 6 show that the ground vias connecting the ground planes are arranged at the positions of L satisfying the above equation (1), so that the center of the operating frequency band can be obtained. This shows that an optimum insertion loss can be obtained at a frequency.

There are various methods for manufacturing the high-frequency transmission line having the structure shown in FIGS. 1 to 3. For example, a predetermined portion of a dielectric sheet having a predetermined width and thickness, such as glass ceramic, is penetrated. Is filled with a conductor such as silver, and a predetermined pattern including a signal line and a ground plane surrounding the signal line is formed on both main surfaces of the dielectric sheet by using a conductor paste such as silver. The conductor paste can be manufactured in a process of simultaneous firing under predetermined conditions. As a result of these steps, the dielectric sheet becomes a dielectric substrate having a thickness of about 0.2 to 0.6 mm.

[0020]

As apparent from the detailed description of one embodiment of the present invention, the present invention provides:
By setting the position of the ground via from the signal line according to the operating frequency and the relative permittivity of the dielectric substrate, it is possible to achieve a special effect that the transmission characteristics of the high-frequency transmission line can be optimized.

[Brief description of the drawings]

FIG. 1 is a front view of one embodiment of a high-frequency transmission line according to the present invention.

FIG. 2 is a sectional view taken along line AA 'of FIG.

FIG. 3 is a sectional view taken along line BB ′ of FIG. 1;

FIG. 4 is a graph showing transmission characteristics of one embodiment of the high-frequency transmission line according to the present invention.

FIG. 5 is a graph for explaining a change in transmission characteristics of the high-frequency transmission line according to the present invention.

FIG. 6 is a graph showing transmission characteristics of another embodiment of the high-frequency transmission line according to the present invention.

FIG. 7 is a perspective view schematically showing a configuration of a conventional high-frequency transmission line.

[Explanation of symbols]

11, 21: signal line, 12, 13, 22, 23: ground plane, 4: via, 5: ground via

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 3/02 H01P 1/04 H01P 3/08 H01P 5/00

Claims (3)

(57) [Claims] 1. A ground plane formed on two opposing main surfaces of a dielectric substrate, wherein the grounded coplanar lines formed on two opposing main surfaces of the dielectric substrate are electrically connected to each other through vias. A high-frequency transmission line electrically connected to each other via a ground via, between a center line of a signal line of the grounded coplanar line and an end of the ground via closest to the center line. Is the distance L (μm), the relative permittivity of the dielectric substrate is εr, and the used frequency is F (GHz), and the distance L is F = M ₀ + M ₁ L, where M ₀ = 188−6. A high-frequency transmission line characterized by being within ± 5% around a value satisfying 0 · εr M ₁ = −0.18 + 0.005 · εr. 2. A first grounded coplanar line having a signal line formed on a first main surface of a dielectric substrate, and a second main line facing the first main surface of the dielectric substrate. A second grounded coplanar line having a signal line formed on a surface, a via electrically connecting between ends of the signal line, a first grounded coplanar line, and the second ground line A ground via electrically connecting a ground plane with the dead coplanar line, wherein a distance between a center line of the signal line and an end of the ground via closest to the center line is L. (Μm), when the relative permittivity of the dielectric substrate is εr, and the frequency used is F (GHz), the distance L is F = M ₀ + M ₁ L, where M ₀ = 188−6.0 · εr M middle-value that satisfies ₁ = -0.18 + 0.005 · _εr High-frequency transmission line, characterized in that is within ± 5% as. 3. A step of forming a conductor pattern forming a grounded coplanar line on two opposing main surfaces of a dielectric substrate, and a via for electrically connecting signal lines of the grounded coplanar line. Forming a ground via electrically connecting the ground planes formed on the opposing main surfaces, wherein a center line of the signal line and a center line closest to the center line are formed. Assuming that the distance from the ground via end is L (μm), the relative permittivity of the dielectric substrate is εr, and the operating frequency is F (GHz), the distance L is F = M ₀ + M ₁ L , M ₀ = 188−6.0 · εr, and M ₁ = −0.18 + 0.005 · εr. The process is ± 5% or less. Method.