Low cross talk connector configuration

Abstract: A low crosstalk connector includes a connector terminal face, and at least three pairs of electrical connector terminals. Each pair of terminals is situated at a different corner of an approximately square terminal pattern projected on the connector terminal face. Pairs of terminals at opposite side ends of the square pattern, are aligned in respective planes that are substantially perpendicular to one another. Pairs of terminals at diagonally opposite corners of the square pattern, are aligned in respective planes that are substantially parallel to one another.

Description: Field of the Invention The present invention relates to configurations for electrical connectors that tend to suppress crosstalk between terminals of the connectors, and particularly to a low crosstalk configuration for jacks and plugs used in high data rate wired networks. Discussion of the Known Art Presently, telephone "modular" plug and jack connectors are used in many communication systems as a primary means for connecting copper wire to equipment. Such connectors, referred to in the industry as, e.g., type RJ-45 connectors, usually have four pairs of connector terminals. The known plugs and jacks are also used to provide simple and reliable "patching" connections between lengths of cable carrying one or more twisted pairs of copper wire conductors. The modular plug and jack connection configuration has become a global standard. The mounting size of a type RJ-45 jack frame measures about 1.651 cm (0.650 inches) by 1.524 cm (0.600 inches). There is a current concern in the connector industry with improving crosstalk performance of the modular type telephone plugs and jacks, especially to allow existing copper cable systems to compete with optical fiber networks. See, for example, U.S. Patents No. 5,399,107 (Mar. 21, 1995); and No. 5,186,647 (Feb. 16, 1993). But characteristics inherent to the existing modular connector interface, tend to limit the amount of crosstalk suppression that can be achieved when using the connectors with copper cable systems. It would therefore be desirable to provide a plug and jack connector interface that excels in crosstalk suppression relative to current modular connector designs. Preferably, such an interface should occupy a cross-section no greater than that of current modular connectors so that large scale field replacements can be easily carried out. EP 755,100 (22 January 1997) discloses a plug and jack contact set for twisted pair cable, wherein contact pins for each wire pair are individually shielded by the plug and the jack connectors for each set. Each pair of contact pins is located adjacent an outer shield cover of the associated connector, to maximize the spacing between pairs of contact pins on the connector. It would of course be desirable to provide a low crosstalk connector configuration that can be applied to existing wire networks without shielding, and nonetheless obtain a high level of crosstalk performance. Summary of the Invention According to the invention, a low crosstalk connector configuration includes a connector terminal face, and at least three pairs of electrical connector terminals wherein each pair of terminals is situated at a different corner of an approximately square pattern projected on the terminal face. Pairs of terminals at opposite side ends of the square pattern, are aligned in respective planes that are substantially perpendicular to one another. Pairs of terminals at diagonally opposite corners of the square pattern, are aligned in respective planes that are substantially parallel to one another. For a better understanding of the invention, reference is made to the following description taken in conjunction with the accompanying drawing and the appended claims. Brief Description of the Drawing In the drawing; FIG. 1 is a cross-sectional representation of a first low crosstalk configuration for two pairs of electrical connector terminals. FIG. 2 is a cross-sectional representation of a second low crosstalk configuration for two pairs of connector terminals; FIG. 3 is a cross-sectional representation of a low crosstalk configuration for three or four pairs of connector terminals; FIG. 4 is a view of an electrical jack connector and a mating plug connector each having the terminal pair configuration of FIG. 3; and FIG. 5 is a side view showing further construction details of the mating jack and plug connectors of FIG. 4. Detailed Description of the Invention FIGS. 1 and 2 are cross-sections of configurations of pairs of electrical connector terminals, which configurations are embodied in the present invention. The terminals may be nearly flush with one or both sides of a terminal face in the plane of the drawing, or the terminals may extend parallel to one another in a direction normal to the view of FIGS. 1 and 2. In FIG. 1, two pairs 10, 12 of connector terminals are positioned such that a spacing X between the terminals of each pair is small relative to a distance Y that separates the two terminal pairs 10, 12. Also, the terminals of the pair 10 are aligned in a respective plane 14 that is substantially perpendicular to a plane 16 containing the terminals of the pair 12. Further, as shown in FIG. 1, the plane 14 which includes the terminal pair 10, coincides with a midpoint of the terminal pair 12. With the configuration of FIG. 1, it can be shown that crosstalk between the two terminal pairs 10, 12 is substantially zero or very minimal. That is, voice/data signals transmitted or received through one terminal pair 10 or 12; are not induced onto the other terminal pair 12 or 10, to any significant degree. In the configuration of FIG. 2, connector terminal pairs 20, 22 are each aligned in respective planes 24, 26 that are substantially parallel to one another. Crosstalk between the terminal pairs 20, 22 is nulled or minimized, when the separation distance Q between midpoints of the terminal pair along a direction parallel to the planes 24, 26, is equal to the separation distance R between the midpoints in a direction perpendicular to the planes 24, 26, and when the inter-terminal spacing T of each terminal pair is small relative to the distance Q (or R). That is, crosstalk is minimized when a line 28 drawn from the center of one terminal pair (e.g., pair 22) to the center of the other terminal pair (e.g., pair 20), forms substantially a 45 degree angle with the plane containing the other terminal pair. To arrive at a low crosstalk connector interface for use in applications now met with four terminal pair (8 terminal) modular type telephone connectors, the optimized configurations or relationships of FIGS. 1 and 2 are applied to minimize crosstalk between all six combinations of four differential (tip/ring) terminal pairs 50, 52, 54 and 56, shown in FIG. 3. In FIG. 3, the terminal pair configuration of FIG. 1 is applied to combinations of differential terminal pairs 50 and 52, pairs 50 and 56, pairs 52 and 54, and pairs 54 and 56, wherein each of these terminal pair combinations is situated at opposite ends of a side of an approximately square pattern 58 projected on a connector terminal face. The configuration of FIG. 2 is applied to the remaining combinations of differential terminal pairs 50 and 54, and pairs 52 and 56, wherein each of the remaining terminal pair combinations are at diagonally opposite corners of the square pattern 58. Crosstalk is a function of, among other things, the spacing of individual connector terminals from one another, the relative orientation of the terminal pairs, the spacing of the terminal pairs from one another, and the dielectric properties of a connector body in which the connector terminals are held in position. The greater the spacing between terminal pairs relative to the inter-terminal spacing of each pair, the less, if any, crosstalk will be induced between the terminal pairs. In practical applications there is a need to provide "miniature" connectors in order to reduce space required for outlets, and to reduce the size of mount openings in panels. Significantly, the arrangement of FIG. 3 can be used in applications now met with telephone type modular connectors such as, for example, the earlier mentioned RJ-45. That is, the FIG. 3 arrangement will exhibit significantly superior crosstalk levels in an envelope size less than that of the current modular connectors. The following data was obtained using two envelope sizes of the four-pair, differential connector terminal configuration of FIG. 3. Crosstalk performance was measured at 100 MHz. Version 1 is for a square terminal pattern 58 measuring 1.397cm (0.550 inches) on a side. Version 2 is for a square pattern measuring 1.143 (0.450 inches) on a side. Differential terminal pairs A, B, C, D correspond to those in FIG. 3. VERSION 1 Terminal Pair Crosstalk (dB down) A-B (adjacent) 84.6 A-C (diagonal) 107 (in noise floor) A-D (adj.) 79.1 B-C (adj.) 85.1 B-D (diag.) 96.5 (near floor) C-D (adj.) 106 (in noise floor) VERSION 2 Terminal Pair Crosstalk (dB down) A-B (adjacent) 72.8 A-C (diagonal) 87.1 A-D (adj.) 70.5 B-C (adj.) 76.7 B-D (diag.) 81.5 C-D (adj.) 74.2 The above data demonstrates that the connector configuration of the invention can be applied in plugs and jacks used to connect copper cables that transmit data at relatively high rates. The configuration will achieve low electrical crosstalk between data transmitting pairs of cable conductors. Until now, crosstalk has been a common problem with connectors used in high data rate cable transmission applications. FIG. 4 is a view showing an electrical jack connector 100 with elongate connector pin terminal pairs 102, 104, 106, 108; and a mating plug connector 120 with elongate connector socket terminal pairs 122, 124, 126, 128; according to the invention. The jack connector 100 has a generally rectangular outer frame body 130, with pairs of resilient snaps 132, 134 projecting from opposed side walls 136, 138 of the connector 100. The outer dimensions of the frame body 130 and its mounting parts may, for example, be compatible with mounts or panel openings that currently accept a type RJ-45 jack connector. Such would facilitate the replacement of existing modular connectors with those of the invention. The plug connector 120 has a generally square connector terminal face 150 with an oblique "key" 152 cut at one corner of the face 150. The key 152 ensures that the plug connector 150 can be inserted with only one (i.e., proper) orientation in the jack connector 100 whose frame body 130 has a corresponding key 154 at a corner of a plug receiving opening 156 in the body 130. When the plug connector is properly inserted in the jack receiving opening 156, the jack connector pin terminal pairs 102, 104, 106, 108 engage corresponding plug connector socket terminal pairs 122, 124, 126, 128 in electrical conducting relation. Preferably, the plug connector 120 has a bendable snap catch 160 formed to project from a side wall of the connector face 150. The catch 160 engages an edge of the plug receiving opening 156 in the jack frame body 130, when the plug connector 120 is fully inserted in the jack receiving opening 156. FIG. 5 is a side view of the connectors 100, 120 in FIG. 4 with associated wire cables 180, 182. The jack connector 100 has a generally conical portion 184 projecting axially toward the rear of the connector 100. The connector 120 also has a conical portion 186 projecting axially rearward. The conical portions 184, 186 serve to guide twisted wire pairs of the cables 180, 182 as they transition from the cables to connect with terminals of the associated connectors 100, 120. The conical portions 184, 186 may also have axially directed ribs or slots (not shown) to limit lateral movement of the wires. Each connector 100, 120 also has an associated conical housing 190, 192. The housings have rear openings that permit passage of an associated cable 180, 182 and the housings are fitted on the connectors over the conical portions 184, 186, with the twisted wire pairs protectively enveloped between the conical portions and the connector housings. It will be understood that FIG. 5 shows only one possible arrangement of connector/housing, and connectors with housings can be constructed using many different arrangements while still applying the terminal pair configuration shown in FIG. 3. The connector terminal configuration of the invention combines two different electrical field relationships, to achieve a very low crosstalk four-terminal pair connector. The connector can be used in applications where telephone type modular connectors are currently used. A jack or plug connector according to the invention exhibits significantly better crosstalk performance, but can fit easily within the physical envelope of an existing modular connector. Connectors according to the invention can be used wherever modular connectors are now being used, for example, in voice and data transmitting applications. Moreover, in addition to enhanced performance, the disclosed connectors should cost no more, and will probably cost less to manufacture than the existing modular connectors. And even more important, the connectors of the present invention will facilitate the use of copper cable transmission systems at data rates higher than those presently attained. While the foregoing description represents preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the true spirit and scope of the invention pointed out by the following claims. For example, for applications requiring only three terminal pairs, the terminal pair configuration of FIG. 3 may be modified by eliminating one of the terminal pairs and leaving the other three in place on the terminal face.

Claims: A low crosstalk connector configuration, comprising: a connector terminal face (58); at least three pairs (50, 54, 56) of elongated, parallel electrical connector terminals, wherein each pair of terminals is aligned in a plane normal to the terminal face; a first pair (50) of the electrical connector terminals is aligned in a first plane that is substantially parallel to a second plane in which a second pair (54) of the terminals is aligned; a first separation distance (Q) between midpoints of the first and the second pairs of terminals in a direction parallel to said planes, is substantially equal to a second separation distance (R ) between the midpoints in a direction perpendicular to the planes; and a third pair of the terminals (56) is aligned in a third plane that is perpendicular to the first and the second planes, and the third plane coincides with a point between either of the first (50) or the second (54) pair of terminals. A connector configuration according to claim 1, including a fourth pair (52) of elongated parallel electrical connector terminals, wherein the fourth pair of terminals is aligned in a fourth plane normal to the terminal face; wherein the fourth plane is substantially perpendicular to the first and the second planes and coincides with the point between either of the first (50) or the second (54) pair of terminals, and the fourth plane is substantially parallel to the third plane; and a first separation distance between midpoints of the fourth (52) and the third (56) pairs of terminals in a direction parallel to the fourth and the third planes, is substantially equal to a second separation distance between said midpoints in a direction perpendicular to the fourth and the third planes. A connector configuration according to claim 1 or 2, wherein at least some of the electrical connector terminals are pin terminals. A connector configuration according to claim 1 or 2, wherein at least some of the electrical connector terminals are socket terminals. A connector configuration according to claim 1 or 2, wherein the third plane coincides with a midpoint between either of the first or the second pair or terminals. A connector configuration according to claim 2, wherein the fourth plane coincides with a midpoint between either of the first or the second pair of terminals. A connector configuration according to any one of the preceding claims, including a length of cable comprising at least three pairs of twisted wires that are electrically connected to corresponding pairs of the connector terminals. A connector configuration according to any of the preceding claims, wherein the connector terminal face has an approximately square configuration, and each pair of electrical connector terminals is situated at a different corner of the configuration. A connector configuration according to claim 8, wherein a side dimension of the terminal face is at most about 1.65 centimeters (0.650 inches). A connector configuration according to claim 8 or 9, including a generally conical connector part extending axially rearward from the terminal face, the part being configured to limit lateral movement of cable wire pairs that transition between an associated cable and the connector terminals. A connector configuration according to claim 10, including a generally conical housing constructed and arranging to fit over the conical connector part with said wire pairs enveloped between the part and said housing.

Inventors: ARNETT JAIME RAY, PHARNEY JULIAN ROBERT, ARNETT, JAIME RAY, PHARNEY, JULIAN ROBERT
Applicants: LUCENT TECHNOLOGIES INC, LUCENT TECHNOLOGIES INC.
Application year: 1999
Main classification: H01R24
IPC codes: H01R25, H01R24, H01R13