JPH0795134A - Balanced transmission line - Google Patents

Abstract

PURPOSE:To provide noise immunity against environment electromagnetic field with an excellent transmission characteristic in which high density is attained. CONSTITUTION:A one side wire pattern L1 forming a balanced transmission line 2 is divided into a forward wire pattern L11 and a rear side wire pattern L12 and similarly the other wire pattern L2 is divided into a forward wire pattern L21 and a rear side wire pattern L22, the forward wire pattern L11 and the rear wire pattern L22 are connected via a throughhole 4-1, the rear wire pattern L12 and the forward wire pattern L21 are connected via a throughhole 4-2, and a twisted structure is provided to a division point P1. Thus, when an electric signal is fed to the wire pattern pairs L1, L2, a crosstalk induced in the balanced transmission line 3 close to the patterns L1, L2 is inverted for the polarity before and after the division point P1, then the crosstalk is cancelled together.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balanced transmission line composed of a pair of wiring patterns opposed to each other with an insulating substrate interposed therebetween and transmitting an electric signal through the pair of wiring patterns.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a balanced transmission line in a conventional printed wiring board. The conventional balanced transmission line 2 (3) is
As shown in the drawing, the wiring pattern pair L1 (L3) and L2 (L4) facing each other with the insulating substrate 1 sandwiched therebetween is formed. The wiring pattern pair L1 (L3) and L2 (L4)
To transmit electrical signals through.

[0003]

However, in the conventional balanced transmission line, a shield pattern (not shown) is used in order to reduce the crosstalk induced in the adjacent balanced transmission line and improve the transmission characteristics. There is a method that there is no other method than sandwiching it or widening the pattern interval of the adjacent wiring patterns, and it is difficult to increase the density of the wiring patterns. On the contrary, when the pattern interval is narrowed and the wiring pattern is densified, the crosstalk that occurs is large, so that there is a drawback that the applicable signal transmission rate can be suppressed low. Further, when there is a noise source such as a broadcasting antenna near the printed wiring board, it is necessary to house the entire printed wiring board in a shielded case, which causes a cost increase.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a balanced transmission line capable of high density and having excellent transmission characteristics and noise resistance against an environmental electromagnetic field. To provide.

[0005]

In order to achieve such an object, the present invention provides a wiring pattern on one side of a wiring pattern pair forming a balanced transmission line in a signal transmission direction in a front wiring pattern and a rear wiring pattern. Similarly, the other side wiring pattern is divided into a front side wiring pattern and a rear side wiring pattern in the signal transmission direction, and the front side wiring pattern of the one side wiring pattern and the rear side of the other side wiring pattern are divided. The wiring pattern is connected by a first conductor provided through the insulating substrate, and the rear wiring pattern on one side of the wiring pattern and the front wiring pattern on the other side of the wiring pattern are passed through the insulating substrate. The connection is made by the provided second conductor.

[0006]

Therefore, according to the present invention, when an electric signal is passed through a pair of wiring patterns facing each other with the insulating substrate interposed therebetween,
The crosstalks induced in the wiring pattern pairs of other adjacent balanced transmission lines have their polarities inverted before and after the dividing point, and thus cancel each other out.

[0007]

EXAMPLES The present invention will now be described in detail based on examples.

[Embodiment 1] FIG. 1 is a perspective view showing an essential part of an embodiment of the present invention, in which a part of an insulating substrate 1 is cut away for easy understanding. In this embodiment, the wiring pattern L1 on one side forming the balanced transmission line 2 is divided into a front wiring pattern L11 and a rear wiring pattern L12 in the signal transmission direction, and similarly, the wiring pattern L2 on the other side is divided.
Is divided into a front side wiring pattern L21 and a rear side wiring pattern L22, and a small diameter through provided through the insulating substrate 1 to the front side wiring pattern L11 and the rear side wiring pattern L22 of the wiring pattern L1. Hall 4
−1, the rear side wiring pattern L12 of the wiring pattern L1 and the front side wiring pattern L21 of the wiring pattern L2.
Are connected to each other by a through hole 4-2 having a small diameter provided through the insulating substrate 1 to provide a twist structure at the dividing point P1.

By providing such a twisted structure,
When an electric signal is passed through the wiring pattern pair L1 and L2, the crosstalk induced from the wiring pattern pair L1 and L2 to the wiring pattern pair L3 and L4 of the adjacent balanced transmission line 3 has the polarity reversed before and after the division point P1. Therefore, they cancel each other out.

Therefore, adjacent wiring pattern pairs L3, L
Even if the pattern interval between the wiring patterns 4 and 4 is narrow, it is possible to reduce the crosstalk induced by the wiring pattern pair L3, L4 by adjusting the number and arrangement of the division points P1. That is, the density of the wiring pattern can be increased, and the applicable signal transmission rate can be increased. Also, as in the case of crosstalk, external noise such as broadcast waves can also be canceled by the twisted structure, so that noise resistance against environmental electromagnetic fields can be improved. Further, the above twisted structure can be realized by an ordinary printed wiring board manufacturing method and does not require a special step,
It does not increase costs. Further, by adjusting the shape of the wiring pattern and the diameter of the through hole at the division point P1, it is possible to further increase the density of the wiring pattern.

[Embodiment 2] FIG. 2 is a perspective view showing an essential part of another embodiment of the present invention, in which a part of the insulating substrate 1 is cut away for easy understanding. In this embodiment, similarly to the first embodiment, the split point P1 is provided at the wiring pattern pair L1 and L2 of the balanced transmission line 2, and the twisted structure is provided at the split point P1. Further, division points P2-1 and P2-2 are provided in the wiring pattern pair L3 and L4 of the balanced transmission line 3,
A twist structure is given to the dividing points P2-1 and P2-2. In this case, the dividing point P1 is arranged on the bisector of the wiring pattern pair L32, L42 of the balanced transmission line 3, and similarly, the dividing points P2-1 and P2-2 are the wiring pattern pair L11, of the balanced transmission line 2. It is arranged on the bisector of L21, L12, and L22. That is, in the present embodiment, the dividing point P1 of the balanced transmission line 2 is the balanced transmission line 3
The division points P2-1 and P2-2 do not overlap each other in the arrangement direction.

By doing so, the division points P1,
The crosstalks induced from the lines before and after P2-1 and P2-2 have the same magnitude and the polarities can be reversed, and the crosstalk is induced from the balanced transmission line 2 (3) to the balanced transmission line 3 (2). Crosstalk can be reduced. In addition, the balanced transmission line 2
The external noises induced in and 3 can be reduced in the same manner as in the case of crosstalk, and the noise resistance against the environmental electromagnetic field can be improved. As a result, it becomes possible to eliminate the case for shielding the entire printed wiring board even in a place where the external noise is bad such as near the broadcast antenna, and in addition to the effect described in the first embodiment, this balance is achieved. It is possible to reduce the cost of the entire device using the transmission lines 2 and 3.

Note that FIGS. 1 and 2 show an example of the wiring pattern shape at the dividing points, and it goes without saying that any shape may be used as long as the wiring pattern shape can realize a twisted structure. In addition, by making the through-holes landless, it is possible to further increase the density of the wiring pattern. Furthermore, in a multi-layer printed wiring board in which wiring patterns are laminated in layers, interstitial via holes (IVH) are used to obtain conduction by penetrating only the insulating substrate portion sandwiched between the required wiring pattern layers, A twisted structure may be added to the balanced transmission line.

[0014]

As is apparent from the above description, according to the present invention, when an electric signal is passed through a pair of wiring patterns facing each other with an insulating substrate interposed therebetween, a pair of wiring patterns of other balanced transmission lines adjacent to each other. Since the crosstalk induced by the signals is canceled out by reversing the polarities before and after the dividing point, it is possible to increase the density of the wiring pattern and increase the applicable signal transmission speed. It has an excellent effect such that it is possible to improve noise resistance against an electromagnetic field.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a main part of an embodiment (Embodiment 1) of the present invention.

FIG. 2 is a partially cutaway perspective view showing an essential part of another embodiment (Embodiment 2) of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of a balanced transmission line in a conventional printed wiring board.

[Explanation of symbols]

 1 Insulating board 2 Balanced transmission line 3 Balanced transmission line L1, L2 Wiring pattern L3, L4 Wiring pattern L11, L21 Front side wiring pattern L12, L22 Rear side wiring pattern 4-1 and 4-2 Through hole P1 Dividing point

Claims (2)

[Claims] 1. A balanced transmission line configured by a pair of wiring patterns facing each other with an insulating substrate sandwiched therebetween and transmitting an electric signal through the pair of wiring patterns, wherein a wiring pattern on one side of the wiring pattern pair is a front side in a signal transmission direction. The wiring pattern is divided into a wiring pattern and a rear wiring pattern, and the wiring pattern on the other side of the wiring pattern pair is divided into a front wiring pattern and a rear wiring pattern in the signal transmission direction, and a front wiring pattern of the one side wiring pattern. And a rear side wiring pattern of the other side wiring pattern are connected by a first conductor provided penetrating the insulating substrate, and a rear side wiring pattern of the one side wiring pattern and the other side wiring The front wiring pattern of the pattern is connected by a second conductor provided penetrating the insulating substrate. Transmission line. 2. A balanced transmission line that is formed of a pair of wiring patterns that face each other with an insulating substrate interposed therebetween and that transmits an electric signal through the pair of wiring patterns, wherein the wiring pattern on one side of the wiring pattern pair is on the front side in the signal transmission direction. The wiring pattern is divided into a wiring pattern and a rear wiring pattern, and the wiring pattern on the other side of the wiring pattern pair is divided into a front wiring pattern and a rear wiring pattern in the signal transmission direction, and a front wiring pattern of the one side wiring pattern. And a rear side wiring pattern of the other side wiring pattern are connected by a first conductor provided penetrating the insulating substrate, and a rear side wiring pattern of the one side wiring pattern and the other side wiring The front side wiring pattern of the pattern is connected by a second conductor provided penetrating the insulating substrate, and the one side and the other side Balanced transmission line, characterized in that the dividing point of the wiring pattern is not overlapped on one side and the division point of the other side of the wiring pattern and its alignment direction of the other balanced transmission line adjacent.