JP2003115704A - High frequency circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a high frequency circuit formed with grounds short-circuited with vias in a tri-plate line has ground-to-ground short- circuiting vias at both sides of a signal line inner conductor in a via layout section, this forming a structure of enclosing the entire signal line inner conductor with the ground to shield this conductor in all directions, compared with a usual tri-plate line, however, in a section without provision of vias, it takes only a usual tri-plate line structure and hence the lateral shield of the signal line inner conductor is lost to result in a poor electromagnetic shield. SOLUTION: The circuit comprises a signal line inner conductor 1 and ground inner conductors 7 disposed in parallel to a signal transmitting direction at both sides of the inner conductor 1 on the same substrate layer as the conductor 1 in a tri-plate line formed on a multilayer circuit board, two grounds 2 sandwiching the inner conductor 1 of the tri-plate line, and a plurality of vias 3 which short-circuit the grounds 2 in a signal propagating direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency circuit electromagnetic shield technique.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing the structure of a conventional high-frequency circuit which is electromagnetically shielded. FIG. 4 (a) is a plan view and FIG.
(B) is a cross-sectional view as seen from AA ', and FIG. 4 (c) is B-
FIG. 1 is a cross-sectional view seen from B ′, 1 is an inner conductor for a signal line, 2 is a ground of a triplate line, 3 is a via, 4 is a high-frequency circuit composed of a multilayer substrate, 5 is a single substrate constituting the multilayer substrate, 6 Is a bonding sheet for connecting the substrates 5.

[0003]

The high frequency circuit 4 having a shape in which the grounds 2 of the triplate line are short-circuited by the vias 3 as described above, as compared with a normal triplate line, as shown in FIG.
In the cross section in which the vias 3 are arranged as described above, there are vias 3 that short-circuit the grounds 2 on both sides of the signal line inner conductor 1, and the entire circumference of the signal line inner conductor 1 is surrounded by the ground. Therefore, the signal line inner conductor 1 is shielded in all directions. However, in the cross section in which the vias 3 are not arranged as shown in FIG. 4C, the structure is only a normal triplate line, and the horizontal shield property of the signal line inner conductor 1 is impaired, so that the electromagnetic shield is not sufficient. There was a problem of coming.

The present invention has been made to solve the above problems, and an object thereof is to enhance the electromagnetic shielding property of a high frequency circuit.

[0005]

A high frequency circuit according to a first aspect of the present invention sandwiches a signal line inner conductor and a signal line inner conductor in a triplate line formed on a multilayer circuit board. Two layers of ground, inner conductors for ground arranged on the same substrate layer as the inner conductor for signal lines and parallel to the signal transmission direction on both sides of the inner conductor for signal lines, and two layers of ground and the ground The inner conductor and a plurality of vias that short-circuit the inner conductor along the signal propagation direction of the inner conductor for signal lines.

In the high frequency circuit according to the second invention,
An inner conductor for ground which is arranged on an inner layer on which the inner conductor for signal line of the high-frequency circuit according to the first invention is not arranged and which is parallel to the signal transmission direction, and an inner conductor for ground on the same substrate layer as the inner conductor for signal line. In this configuration, the conductor and the ground of the two layers sandwiching the signal line inner conductor of the triplate line are short-circuited by a plurality of vias along the signal propagation direction.

In the high frequency circuit according to the third invention,
In a cross section of the high-frequency circuit according to the second aspect of the invention, the inner conductor for ground is arranged in a circle with the inner conductor for signal line as a center, and between the inner conductors for ground and between the ground of the triplate line and the inner conductor for ground. The configuration is such that a plurality of vias are provided along the signal propagation direction so that the cross section including the vias is concentric with the inner conductor for ground and the via as concentric circles centering on the inner conductor for signal line.

In the high frequency circuit according to the fourth invention,
In the high frequency circuit according to the first to fourth aspects of the invention, the via pitch is arranged along the signal propagation direction at ¼ or less of the wavelength of the signal propagating through the high frequency circuit.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 is a block diagram of a high frequency circuit showing a first embodiment of the present invention.
1A is a plan view, FIG. 1B is a cross-sectional view as seen from CC ′, FIG. 1C is a cross-sectional view as seen from DD ′, and 7 is an inner conductor 1 for a signal line. The inner conductors for ground are disposed on both sides of the inner conductor 1 for signal lines on the same substrate layer and in parallel with the signal transmission direction. In FIG. 1, 1 to 6 are the same as in the conventional description.

The via 3 is composed of the ground 2 and the ground inner conductor 7.
Are short-circuited and a plurality of them are arranged along the signal propagation direction.

According to the above embodiment, the via 3
In the cross section in which is arranged, as shown in FIG. 1B, since the entire circumference of the signal line inner conductor 1 is surrounded by the ground, the signal line inner conductor 1 is shielded in all directions. There is. Even in the cross section in which the vias 3 are not arranged as shown in FIG. 1C, the structure is such that the inner conductor 7 for ground is arranged on both sides of the inner conductor 1 for signal line. Therefore, compared to the conventional electromagnetic shielded high frequency circuit. A high-frequency circuit that has excellent electromagnetic shielding properties and is resistant to signal line interference.

Embodiment 2. 2 is a configuration diagram of a high-frequency circuit showing a second embodiment of the present invention, FIG. 2 (a) is a plan view, FIG. 2 (b) is a cross-sectional view seen from EE ′, and FIG. 2 (c).
FIG. 6 is a cross-sectional view seen from FF ′. In FIG. 2, 7a
Is an inner conductor for ground on the same substrate layer as the inner conductor 1 for signal line, 7b is an inner conductor for ground on a substrate layer on which the inner conductor for signal line is not arranged, and 1 to 6 are the same as the conventional description It is a thing.

A plurality of vias 3 short-circuit the ground 2 and all the ground inner conductors 7 arranged in the inner layer of the substrate, and a plurality of vias 3 are arranged along the signal propagation direction.

According to the above embodiment, the via 3
2B, the signal line inner conductor 1 is shielded in all directions because the signal line inner conductor 1 has a structure in which the entire circumference is surrounded by the ground as shown in FIG. 2B. There is. Even in a cross section in which the vias 3 are not arranged as shown in FIG. 2C, the ground inner conductors 7a are arranged on both sides of the signal line inner conductor 1 and the ground inner conductors 7b are arranged on the outer periphery. Therefore, the high-frequency circuit is more excellent in electromagnetic shielding than the first embodiment and resistant to signal line-to-line interference.

Embodiment 3. 3 is a configuration diagram of a high frequency circuit showing Embodiment 3 of the present invention, FIG. 3 (a) is a plan view, FIG. 3 (b) is a cross-sectional view seen from GG ′, and FIG. 3 (c).
Is a cross-sectional view seen from H-H '. In FIG. 3, 1 to
6 is the same as the conventional description, and 7a and 7b are the same as those in the second embodiment.

A plurality of vias 3 short-circuit the ground 2 and all the ground inner conductors 7 arranged in the inner layer of the substrate, and a plurality of vias 3 are arranged along the signal propagation direction. In addition, the inner conductor for ground 7 and the via 3 are shown in FIG.
As shown in (b), they are arranged so as to form a concentric circle centered on the signal line inner conductor 1.

According to the above embodiment, the via 3
In the cross section in which is arranged, as shown in FIG. 3B, the inner circumference of the signal line inner conductor 1 is surrounded by the ground, so that the signal line inner conductor 1 is shielded in all directions. There is. Even in a cross section in which the vias 3 are not arranged as shown in FIG. 3C, the inner conductor for ground 7a is arranged on both sides of the inner conductor for signal line 1 and the inner conductor for ground 7b is arranged on the outer periphery. Therefore, the high frequency circuit is superior in electromagnetic shielding property to the first embodiment and resistant to signal line interference. Further, the ground inner conductors 7a and 7b and the via 3 are used for the signal line inner conductor 1 in both the cross section where the via 3 is arranged and the cross section where the via 3 is not arranged
Since they are arranged in a concentric circle shape centering on the center, the ground inner conductors 7a and 7b and the via 3 near the substrate 5 farther from the signal line inner conductor 1 than in the first and second embodiments are used for the signal line. It is arranged close to the inner conductor 1 and has excellent electromagnetic shielding properties.

Further, in the first to third embodiments, the radiation of the signal can be improved by arranging the pitch of the adjacent vias 3 in the signal propagation direction to be ¼ or less of the wavelength of the signal to be propagated.

[0019]

According to the present invention, the electromagnetic shielding performance of the high frequency circuit formed on the multilayer substrate can be enhanced, and the influence of the signal line interference or the electromagnetic interference generated between other high frequency circuits can be suppressed.

[0020]

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a high-frequency circuit according to the present invention.

FIG. 2 is a diagram showing a second embodiment of a high-frequency circuit according to the present invention.

FIG. 3 is a diagram showing a third embodiment of a high-frequency circuit according to the present invention.

FIG. 4 is a diagram showing a configuration of a conventional high-frequency circuit that is electromagnetically shielded.

[Explanation of symbols]

1 inner conductor for signal line, 2 ground, 3 via,
4 high frequency circuit, 5 substrate, 6 bonding sheet, 7 inner conductor for ground

Claims (4)

[Claims] 1. In a triplate line formed on a multilayer circuit board, an inner conductor for a signal line that allows a high frequency signal to pass therethrough, two layers of grounds sandwiching the inner conductor for the signal line, and an inner conductor for the signal line. An inner conductor for ground arranged on the same substrate layer as the inner conductor for signal line and parallel to the signal transmission direction on both sides of the inner conductor for signal line; And a plurality of vias that are short-circuited along the signal propagation direction of the high frequency circuit. 2. An inner conductor for ground which is arranged on an inner layer where the inner conductor for signal line is not arranged and which is parallel to the signal transmission direction, and an inner conductor for ground which is on the same substrate layer as the inner conductor for signal line. The high frequency circuit according to claim 1, wherein the grounds of the two layers sandwiching the signal line inner conductor of the triplate line are short-circuited by a plurality of vias along the signal propagation direction. 3. An inner conductor for ground is arranged on a circle centering on the inner conductor for signal line, and between the inner conductors for ground and between the ground of the triplate line and the inner conductor for ground along the signal propagation direction. 3. The plurality of vias are short-circuited so that a cross section including the vias is concentric with the inner conductor for ground and the via for the inner conductor for signal line as a center. High frequency circuit. 4. The vias in the signal propagation direction are arranged along the signal propagation direction at a pitch of ¼ or less of a wavelength of a signal propagating in a high frequency circuit.
1. The high frequency circuit according to any one of 1 to 3.