Abstract:
An electrical circuit arrangement includes at least three adjacent spaced-apart, elongate parallel conductors. Specifically, a middle conductor has two oppositely facing first and second surfaces. A left conductor has a surface facing the first surface of the middle conductor to define a first electrical coupling. A right conductor has a surface facing the second surface of the middle conductor to define a second electrical coupling. The shape of the facing surfaces between the left conductor and the middle conductor is different from the shape of the facing surfaces between the right conductor and the middle conductor. Therefore, the electrical characteristics of the first electrical coupling is different from the electrical characteristics of the second electrical coupling.

Description:
FIELD OF THE INVENTION 
     This invention generally relates to the art of electrical conductors or terminals and, particularly, to an electrical circuit arrangement for controlling the electrical characteristics between adjacent conductors. 
     BACKGROUND OF THE INVENTION 
     In electrical circuit arrangements, including adjacent conductors or terminals in high speed digital systems, there is a continuing problem of &#34;crosstalk&#34; (horizontal capacitance) between adjacent conductors. Such crosstalk occurs in many electrical devices such as modular jack connectors, input-output connectors, other connectors of various types, electrical cables and arrays of terminal pins. 
     In the past, various schemes, constructions or methods have been used to uniformly reduce the crosstalk between conductors in any given electrical circuit arrangement. The invention herein is designed to selectively control crosstalk between various conductors or terminals in a given electrical circuit arrangement, rather than simply trying to wholesale eliminate the crosstalk. 
     SUMMARY OF THE INVENTION 
     An object, therefore, of the invention is to provide an electrical circuit arrangement wherein the electrical characteristics, such as the crosstalk (horizontal capacitance) between selected conductors in the circuit arrangement, is different. 
     In one embodiment of the invention, an electrical circuit arrangement includes at least three adjacent spaced-apart, elongate parallel conductors including a middle conductor having two oppositely facing surfaces. A left conductor has a surface facing the first surface of the middle conductor to define a first electrical coupling. A right conductor has a surface facing the second surface of the middle conductor to define a second electrical coupling. 
     The invention contemplates that the shape of the facing surfaces between the left conductor and the middle conductor be different from the shape of the facing surfaces between the right conductor and the middle conductor. Therefore, the electrical characteristics of the first electrical coupling is different from the electrical characteristics of the second electrical coupling. 
     As disclosed herein, the facing surfaces between one of the left or right conductors and the middle conductor are narrower than the facing surfaces between the other of the left or right conductors and the middle conductor. The narrower facing surfaces cause less crosstalk (horizontal capacitance) than the wider surfaces. In one embodiment of the invention, the facing surfaces between at least one of the left or right conductors and the middle conductor are pointed. In another embodiment, the facing surfaces between at least one of the left or right conductors and the middle conductor are generally flat. In still a further embodiment, the facing surfaces between at least one of the left or right conductors and the middle conductor are rounded. 
     The concepts of the invention comprising the unique electrical circuit arrangement are shown herein in one embodiment wherein the conductors are in a generally parallel array in an electrical cable. In another embodiment, the conductors comprise terminals in an electrical connector. 
     Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features of this invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with its objects and the advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements in the figures and in which: 
     FIG. 1 is a perspective view of an electrical connector wherein an electrical circuit arrangement according to the invention has applicability; 
     FIG. 2 is a fragmented front elevational view of the connector of FIG. 1; 
     FIG. 3 is a fragmented top plan view of the connector of FIG. 2; 
     FIG. 4 is a section through a flat electrical cable embodying an electrical circuit arrangement incorporating the concepts of the invention; 
     FIG. 5 is a computer generated diagram of the electrical field between the terminals in the connector of FIGS. 1-3, as through the tails of the connector generally along line 5--5 of FIG. 3; 
     FIG. 6 is a computer generated diagram of the electrical field between the conductors in the cable of FIG. 4; 
     FIG. 7 is a section through another flat cable having conductors with somewhat different configurations than the conductor in FIG. 4; 
     FIG. 8 is a fragmented section through a single conductor having a different edge configuration; 
     FIG. 9 is a view similar to that of FIG. 8, with the conductor having still another different edge configuration; 
     FIG. 10 is a view similar to that of FIGS. 8 and 9, with the conductor having yet a further different edge configuration; and 
     FIG. 11 is an illustration of the invention incorporated in the conductors between two rows of conductors. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in greater detail, FIGS. 1-3 show an electrical connector in which an electrical circuit arrangement according to the invention has applicability. In particular, an electrical connector 12 includes an elongated dielectric housing 14, such as of molded plastic material or the like. The housing has a receptacle 16 defining a mating face of the connector for mating with a complementary connector, such as a plug connector inserted into receptacle 16. The opposite face 18 of the housing is adapted for surface mounting on a printed circuit board. FIG. 3 shows that a pair of boardlocks 20 may depend from housing 14 for insertion into appropriate mounting holes in the printed circuit board. A polarizing peg 22 also may depend from housing 14 for inserting into a polarizing hole in the circuit board. The housing mounts a plurality of terminals 24 which, as best seen in FIG. 2, are arranged in two rows lengthwise of the housing. The terminals have tails portions 24a, also in two rows and depending from surface 18 of the housing for insertion into appropriate holes in the printed circuit board. The tails typically are soldered to circuit traces on the board and/or in the holes. To this extent, connector 12 is generally conventional. 
     FIG. 4 shows a generally flat electrical cable, generally designated 26, which includes a dielectric 28 surrounding three pairs of conductors 30a,30b; 32a,32b and 34a,34b. Therefore, conductors 30a and 30b comprise a left-hand pair, conductors 32a and 32b comprise a center pair and conductors 34a and 34b comprise a right-hand pair. It can be seen that the facing surfaces 36 between the conductors in each pair are generally flat. However, the facing surfaces 38 between the conductors of two adjacent pairs are pointed. Of course, this results in the facing flat surfaces 36 forming a greater interface area than the opposing pointed surfaces 38. 
     Referring to FIG. 5, this diagram shows a section through three pairs of the terminal tails 24a in each of the two rows of terminals in connector 12 as might be taken along line 5--5 of FIG. 3. For clarity of description and understanding as well as cohesion between FIGS. 4-6, the terminal tails 24a in FIG. 5 have been numbered corresponding to the conductors in FIG. 4 so that the depiction in FIG. 5 includes two rows of conductors (terminal tails) with three pairs of conductors (terminal tails) in each row. Therefore, as with the conductors in FIG. 4, the conductors or terminal tails in each of the top and bottom rows in FIG. 5 include a left-hand pair 30a,30b; a center pair 32a,32b and a right-hand pair 34a,34b. Again, the facing surfaces 36 between the conductors in each pair are relatively large and flat, whereas the facing surfaces 38 between the conductors of adjacent pairs are relatively narrow and pointed. 
     It should be understood that when dealing with electrical &#34;pairs&#34; of conductors as described above in relation to FIGS. 3-6, the electrical lines in each pair of conductors are electrically driven together. The electrical coupling between the conductors in each commonly driven pair is quite high. In addition, crosstalk between the conductors of any commonly driven pair can be beneficial. 
     FIGS. 5 and 6 represent computer generated diagrams of the electrical fields between the conductors in connector 12 (FIGS. 1-3) and cable 26 (FIG. 4), respectively. In other words, FIG. 5 corresponds to the terminal tails 24a of connector 12, and FIG. 6 corresponds to the conductors of cable 26 in FIG. 4. 
     Before going into detail of the computer generated diagrams of FIGS. 5 and 6, it should be understood that, very generally, capacitance is proportional to the amount of energy stored in the electrical field in and around a particular structure (e.g. conductor). In a circuit, capacitance is proportional to the amount of energy stored in the electric field due to the voltage differential across a dielectric whether it be plastic or air. In the following equation: 
     
         U.sub.e =1/2Cv.sup.2 
    
     U e  is the energy stored in the electric field, C is the capacitance, and v is the voltage across the dielectric. The computer generated diagrams of FIGS. 5 and 6 were made by using the Maxwell 2D Parameter Extractor software version 1.7.06 published by Ansoft Corporation. The software computes the capacitance between two lines or conductors by first simulating the electric field that arises when a voltage differential is applied and then computing the energy stored in the simulated field. It then solves for capacitance in terms of the computed field energy (U e ) in the following equation: ##EQU1## This software was used to generate the electric field diagrams of FIGS. 5 and 6. 
     In FIGS. 5 and 6, solid field lines 40 represent the highest electrical field magnitude (volts). Dotted field lines 42 represent the lowest electric field magnitude. Dashed field lines 44 represent the electric field of intermediate magnitude. Of course, it should be understood that whereas capacitance is proportional to the amount of energy stored in the electric field in and around the conductors, the capacitance is proportional to or represents the &#34;coupling&#34; between the conductors. The capacitance also is related to the crosstalk between the conductors. 
     With the above understanding, it can be seen in FIGS. 5 and 6 that field lines 40 of highest electric field magnitude are quite scattered or broad in the area between larger flat facing surfaces 36 of the conductors in each pair 30a,30b; 32a,32b and 34a,34b thereof. This would represent a high coupling between the conductors of any given pair, as well as high crosstalk but, it should be understood, that crosstalk between cooperating pairs of conductors may not be a problem. 
     On the other hand, it can be seen in FIGS. 5 and 6 that the field lines 40 of highest electric field magnitude in the area between facing pointed surfaces 38 are considerably closer together or in a tight pattern representing a lesser capacitance field and, correspondingly, lesser crosstalk. This is of considerable advantage, because it is not desired to have significant crosstalk between the conductors of adjacent pairs. 
     By varying the area of the facing surfaces between adjacent conductors, the capacitance field and, therefore, the crosstalk between the adjacent conductors can be varied or controlled. The examples of FIGS. 1-6 wherein it is desirable to minimize the magnitude of the electric field (i.e. capacitance coupling or crosstalk) between the conductors of adjacent pairs thereof, while allowing significantly higher electric field magnitudes (i.e. capacitance coupling or crosstalk) between the conductors of any given pair, is but one application of the invention involving controlling the electrical characteristics or the electrical coupling between adjacent conductors. 
     FIG. 7 shows another generally flat electrical cable, generally designated 26&#39;, which includes a dielectric 28&#39; surrounding three pairs of conductors 30a&#39;,30b&#39;; 32a&#39;,32b&#39; and 34a&#39;,34b&#39;. Cable 26&#39; is similar to cable 26 (FIG. 4) except that opposing flat surfaces 36 between the conductors of each pair and opposing pointed surfaces 38 between the conductors of adjacent pairs are formed on generally flat or planar conductors versus the curved conductors shown in FIG. 4. 
     FIGS. 8-10 simply show further examples of reducing the area of the facing surfaces of conductors versus the pointed surfaces 38 in the embodiments described hereinbefore. In all of FIGS. 8-10, the conductors are embedded in a dielectric 28. 
     Specifically, in FIG. 8, conductor 50 has a rounded edge 50a to reduce the surface area which would face an adjacent conductor. In FIG. 9, conductor 52 has a quarter-round surface 52a which still reduces the edge surface area. In FIG. 10, conductor 54 has a flat surface 54a, but the flat surface is considerably narrower than the flat surfaces 36 described above, because the remainder of the edge 54b of the conductor is tapered or angled back toward the adjacent side of the conductor. In all of the embodiments of FIGS. 7-10, by opposing the conductors with another conductor of a similarly reduced surface area, the capacitance coupling between the adjacent couplings is minimized which, in appropriate applications, is effective to also minimize the crosstalk between the adjacent conductors. 
     Lastly, FIG. 11 is an illustration which shows an electrical circuit arrangement, generally designated 58, in which not only can the crosstalk between adjacent conductors in any given row of conductors (i.e. FIGS. 5 and 6) be controlled, but the crosstalk or capacitive coupling between the conductors in adjacent rows also can be controlled. In particular, FIG. 11 shows three pairs of conductors 60a,60b; 62a,62b and 64a,64b in each of two rows, generally designated 66 and 68. As with the descriptions of the arrays of conductors in FIGS. 5 and 6, larger flat surfaces 36 between any two adjacent conductors will create an electric field of a higher magnitude and, therefore, a higher coupling, than the field between facing pointed surfaces 38. 
     However, it should be noted that the surfaces 70 between conductors 60a, between conductors 60b, between conductors 62a, between conductors 64a and between conductors 64b in the two rows 66 and 68 are rounded in comparison to the larger flat opposing surfaces 72 between conductors 62b in the two rows. Therefore, larger flat surfaces 72 between adjacent conductors 62b in the two rows will create a higher electric field magnitude and, therefore, a higher capacitive coupling, than either the opposing or facing pointed surfaces 38 or the opposing, facing rounded surfaces 70 between any other two conductors in either row or in the adjacent conductors in both rows. 
     It should be understood that such terms as &#34;left&#34; and &#34;right&#34; have been used herein and in the claims hereof to facilitate a concise description and better understand of the invention. Such terms are not intended in any way to be limiting, because it is clearly understandable that the concepts of the invention are embodied in electrical circuit arrangements which are totally omni-directional in nature. 
     It will be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.