JP2016126966A - High-speed transmission cable module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-speed transmission cable module capable of suppressing crosstalk between cables.SOLUTION: A high-speed transmission cable module comprises: a plurality of cables 2 each having a differential signal transmission line 5 obtained by covering two signal lines 5a with an insulator 5b and forming a shield layer 5c around the insulator 5b; and a common connector 3 to which terminals on one end of the respective cables 2 are collectively connected. The common connector 3 comprises a common circuit board 9 to which the differential signal transmission line 5 of each of the plurality of cables 2 is connected. On the circuit board 9, ground wiring 11 to which the shield layer 5c is electrically connected is dividedly formed at least for each of the cables 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a high-speed transmission cable module.

  High-speed transmission with multiple cables equipped with differential signal transmission lines for transmitting differential signals and a common connector (called a common connector) in which one end of the multiple cables is connected together Cable modules are known.

  Each cable has a structure in which a plurality of differential signal transmission lines with two signal lines covered with an insulator and a shield layer around the insulator are twisted together, and twisted differential signal transmission A braided shield and a sheath are sequentially provided around the wire. The cable having such a structure is also called a composite cable, and the whole bundle of the composite cables is also called a composite cable assembly.

  Each of the plurality of cables provided with an individual connector (referred to as an individual connector) at the other terminal is called a breakout cable. In other words, a breakout cable is configured by bundling a plurality of cables extending from individual connectors and providing a common connector at the bundled terminal, and is used when connecting at one to a plurality of locations. It is.

  In a high-speed transmission cable module such as the breakout cable described above, a common circuit board to which differential signal transmission lines of a plurality of cables are connected is provided inside the common connector. On the circuit board, signal pads to which signal lines of differential signal transmission lines are electrically connected and ground pads to which shield layers are electrically connected are formed.

  In a conventional high-speed transmission cable module, the ground wiring including the ground pad is commonly used for all the differential signal transmission lines on the circuit board.

  In addition, there exists patent document 1 as prior art document information relevant to invention of this application.

JP 2007-87877 A

  However, in the above-described conventional high-speed transmission cable module, since the ground wiring is common to all the differential signal transmission lines, the ground potential (shield layer potential) of the differential signal transmission lines of all the cables. There is a problem that crosstalk (signal interference) occurs between the cables.

  In particular, in the breakout cable described above, the connection destination of each cable is different, and therefore, if the ground potential is common, problems such as noise are likely to occur.

  Therefore, an object of the present invention is to provide a high-speed transmission cable module that can solve the above-described problems and can suppress crosstalk between cables.

  The present invention has been devised to achieve the above object, and includes a plurality of differential signal transmission lines each including two signal lines covered with an insulator and a shield layer formed around the insulator. A common connector to which one end of the plurality of cables is collectively connected, and the common connector is a common circuit board to which the differential signal transmission lines of the plurality of cables are connected The circuit board is a high-speed transmission cable module in which a ground wiring to which the shield layer is electrically connected is divided at least for each of the cables.

  The circuit board is a multilayer board, and the ground wiring includes a ground pad to which the shield layer is fixed, a ground pattern formed on the circuit board in a layer different from the ground pad, and the ground pad and the ground wiring. And a through hole that electrically connects the two.

  The differential signal transmission line is connected to the front and back surfaces of the circuit board, the ground pattern is formed on the inner surface of the circuit board, and the ground pad is formed on the surface of the circuit board. And the ground pattern formed on the front surface side of the circuit board are electrically connected by the through hole, and are formed on the back surface side of the circuit board and the ground pad formed on the back surface of the circuit board. The ground pattern may be electrically connected through the through hole.

  The cable includes a pair of the differential signal transmission lines, and is configured to dispose the pair of differential signal transmission lines so as to face the front and back surfaces of the circuit board. The two layers of ground patterns corresponding to the lines may be electrically connected by a ground pattern connecting through hole.

  Individual connectors may be provided on the other terminals of the plurality of cables.

  ADVANTAGE OF THE INVENTION According to this invention, the cable module for high speed transmission which can suppress the crosstalk between cables can be provided.

It is a figure which shows the cable module for high-speed transmission which concerns on one Embodiment of this invention, (a) is a perspective view, (b) is the 1B-1B sectional view taken on the line. It is a cross-sectional view of the cable used for the high-speed transmission cable module of FIG. It is a figure which shows the cable module for high-speed transmission which concerns on one modification of this invention, (a) is a perspective view, (b) is the 3B-3B sectional view taken on the line.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1A and 1B are diagrams showing a high-speed transmission cable module according to the present embodiment, in which FIG. 1A is a perspective view and FIG. 1B is a sectional view taken along line 1B-1B. FIG. 2 is a cross-sectional view of the cable.

  As shown in FIG. 1 and FIG. 2, a high-speed transmission cable module 1 includes a plurality of (here, four) cables 2 each having a differential signal transmission line 5 for transmitting a differential signal, and a plurality of cables. 2 and a common connector 3 to which one terminal is connected in a lump.

  Although not shown in FIG. 1 (a), the high-speed transmission cable module 1 is provided with individual connectors respectively provided on the other end of the plurality of cables 2, and is a break that is connected at one-to-multiple locations. It is an out cable.

  The cable 2 is configured by sequentially providing a braided shield 6 and a sheath 7 around the differential signal transmission line 5. The differential signal transmission line 5 is configured by individually covering two signal lines 5a with an insulator 5b and providing a shield layer 5c around the insulator 5b. Here, the insulator 5b is provided so as to individually cover the two signal lines 5a, but the insulator 5b may be provided so as to cover the two signal lines 5a in a lump. As the insulator 5b, a non-foamed resin may be used, or a foamed resin such as foamed polyethylene or foamed Teflon may be used. The shield layer 5c is configured, for example, by winding a metal tape around the insulator 5b.

  Here, a cable 2 having two differential signal transmission lines 5 for transmission / reception of one channel is used. Each cable 2 is configured by twisting two differential signal transmission lines 5 and sequentially providing a braided shield 6 and a sheath 7 around the cables.

  One terminal of the four cables 2 is provided with a common connector 3 for four channels, and the other terminal of each cable 2 is provided with an individual connector for one channel.

  The high-speed transmission cable module 1 corresponds to, for example, 10 gigabit Ethernet connection (10GBASE-T, Ethernet is a registered trademark). Good. As the common connector 3, for example, a QSFP + (Quad Small Form-factor Pluggable Plus) connector is used. Moreover, as the individual connector 4, for example, an SFP + (Small Form-factor Pluggable Plus) connector is used.

  A covering material 8 for bundling the four cables 2 is provided around the four cables 2 extending from the common connector 3 for easy handling. Here, a braided tube made of polyester that is easily bent is used as the covering material 8. The covering material 8 can be omitted.

  Hereinafter, the connection between the cable 2 and the common connector 3 will be described in detail.

  The common connector 3 includes a common circuit board 9 to which the differential signal transmission lines 5 of the plurality of cables 2 are connected. Although not shown, the common connector 3 includes a case provided so as to cover the terminal of the cable 2 and the circuit board 9, and the case and the braided shield 6 of each cable are electrically connected. .

  On the circuit board 9, a signal wiring 10 to which the signal line 5a of the differential signal transmission line 5 is electrically connected and a ground wiring 11 to which the shield layer 5c is electrically connected are formed.

  In the present embodiment, a multilayer substrate having four layers is used as the circuit board 9, a signal pattern which is the signal wiring 10 is formed on the front and back surfaces of the circuit board 9, and a ground which is a part of the ground wiring 11 is formed on the inner layer two layers. A pattern 11b is formed. A ground pad 11a for soldering and fixing the shield layer 5c of the differential signal transmission line 5 is formed at the end of the circuit board 9 on the cable connection side on the front and back surfaces. The ground pad 11a formed on the surface of the circuit board 9 and the ground pattern 11b formed on the surface side of the circuit board 9 are electrically connected through the through hole 11c, and the ground pad formed on the back surface of the circuit board 9 11a and the ground pattern 11b formed on the back side of the circuit board 9 are electrically connected through a through hole 11c. Here, the entire ground pad 11a, the ground pattern 11b, and the through hole 11c are referred to as the ground wiring 11.

  Now, in the high-speed transmission cable module 1 according to this embodiment, the ground wiring 11 to which the shield layer 5 c is electrically connected is formed on the circuit board 9 so as to be divided at least for each cable 2.

  That is, in the present embodiment, the ground pad 11a and the ground pattern 11b constituting the ground wiring 11 are separated for each cable 2.

  In the present embodiment, each cable 2 includes a pair of differential signal transmission lines 5, and the pair of differential signal transmission lines 5 constituting each cable 2 is arranged to face the front and back surfaces of the circuit board 9. In addition, since the cables 2 are arranged in the width direction of the circuit board 9 (the left-right direction in FIG. 1B), the ground pads 11a and the ground patterns 11b correspond to the cables 2. It is divided into four in the width direction.

  In the present embodiment, two layers of ground patterns 11b corresponding to a pair of differential signal transmission lines 5 of each cable 2 are electrically connected by a ground pattern connecting through hole 11d, so that they are included in the same cable 2. The ground wiring 11 of the differential signal transmission line 5 is connected to have the same potential. However, for example, when crosstalk between transmission and reception becomes a problem, the ground pattern connection through hole 11d may be omitted to separate the two layers of the ground pattern 11b. Further, when the cable 2 includes a plurality of pairs of differential signal transmission lines 5 and is configured to perform communication of a plurality of channels, the ground wiring 11 may be separated for each channel.

  As described above, in the high-speed transmission cable module 1 according to the present embodiment, the ground wiring 11 to which the shield layer 5c is electrically connected is formed on the circuit board 9 so as to be divided at least for each cable 2. ing.

  As a result, the ground potential (potential of the shield layer 5c) of the differential signal transmission line 5 of each cable 2 can be separated, the occurrence of crosstalk between the cables 2 is suppressed, and the occurrence of noise is suppressed. It becomes possible. The present invention is particularly effective in a breakout cable in which the connection destination of each cable 2 is different.

  The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the pair of differential signal transmission lines 5 of each cable 2 is arranged to face the front and back surfaces of the circuit board 9, but for example, as shown in FIGS. 3 (a) and 3 (b), There may be a case where the pair of differential signal transmission lines 5 of each cable 2 is not disposed opposite to the front and back surfaces of the circuit board 9. In such a case, in order to suppress the occurrence of crosstalk between the cables 2, it is desirable to omit the ground pattern connecting through hole 11d and separate the two layers of the ground pattern 11b.

DESCRIPTION OF SYMBOLS 1 High-speed transmission cable module 2 Cable 3 Common connector 5 Differential signal transmission line 5a Signal line 5b Insulator 5c Shield layer 8 Cover material 9 Circuit board 10 Signal wiring 11 Ground wiring 11a Ground pad 11b Ground pattern 11c Through hole 11d Ground pattern Through hole for connection

Claims (5)

A plurality of cables including a differential signal transmission line in which two signal lines are covered with an insulator and a shield layer is formed around the insulator;
A common connector to which one terminal of the plurality of cables is connected in a lump;
The common connector includes a common circuit board to which the differential signal transmission lines of the plurality of cables are connected,
A high-speed transmission cable module, wherein a ground wiring to which the shield layer is electrically connected is formed on the circuit board at least for each of the cables. The circuit board comprises a multilayer board;
The ground wiring includes a ground pad to which the shield layer is fixed, a ground pattern formed on the circuit board in a layer different from the ground pad, and a through hole that electrically connects the ground pad and the ground wiring. The high-speed transmission cable module according to claim 1. The differential signal transmission line is configured to be connected to the front and back surfaces of the circuit board,
Two layers of the ground pattern are formed on the inner layer of the circuit board,
The ground pad formed on the surface of the circuit board and the ground pattern formed on the surface side of the circuit board are electrically connected by the through hole,
The cable module for high-speed transmission according to claim 2, wherein the ground pad formed on the back surface of the circuit board and the ground pattern formed on the back surface side of the circuit board are electrically connected by the through hole. . The cable includes a pair of differential signal transmission lines, and is configured to dispose the pair of differential signal transmission lines opposite to the front and back surfaces of the circuit board,
The high-speed transmission cable module according to claim 3, wherein the two layers of ground patterns corresponding to the pair of differential signal transmission lines are electrically connected by ground pattern connection through holes. The high-speed transmission cable module according to claim 1, wherein an individual connector is provided on each of the other terminals of the plurality of cables.

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