Abstract:
An array of electrical conductors, the array including an input zone, a first inductive cross talk compensation zone downstream from the input zone, and a second inductive cross talk compensation zone downstream from the first inductive cross talk compensation zone, the first inductive cross talk compensation zone of the array being configured to induce corrective mutual inductance therein for reducing cross talk caused by undesirable mutual inductance in the input zone of the array, and the second inductive cross talk compensation zone of the array being configured to induce corrective mutual inductance therein for reducing cross talk caused by undesirable mutual inductance in the input zone of the array and caused by undesirable mutual inductance in the first inductive cross talk compensation zone of the array.

Description:
[0001]    This is a U.S. nonprovisional patent application relating to and claiming the benefit of the U.S. provisional patent application having the serial No. 60/328,512, which was filed in the U.S. Patent &amp; Trademark Office on Oct. 10, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates to electrical connectors which are susceptible to cross talk between pairs of conductors.  
           [0003]    RJ type TIA plugs and jacks include pairs of closely parallel conductors. At higher frequencies, for example, above 1 MHz, an unacceptable amount of cross talk occurs between the conductors, and between pairs of conductors. This is due to the fact that conductors, including contacts, are closely spaced which encourages both capacitive and inductive couplings. In general, capacitive couplings occur between individual closely spaced conductors, while inductive couplings occur between pairs of closely spaced pairs of conductors.  
           [0004]    Cross talk due to capacitance can be alleviated by crossing certain conductors in the jack lead frame or contact array, as taught by U.S. Pat. No. 5,186,647 issued to Denkmann et al, so that in effect, the polarity of the cross talk is reversed, thereby canceling the cross talk. Cross talk cancellation may also be accomplished on a circuit board to which the jack is attached, as taught in U.S. Pat. No. 5,299,956 issued to Brownell et al.  
           [0005]    It is also desirable to reduce the inductive component of cross talk. One approach to inductive cross talk reduction is disclosed in U.S. Pat. No. 5,700,167 issued to Pharney et al. The Pharney patent teaches the printing of mirror image facing loops on opposing sides of a circuit board to compensate for inductive cross talk arising in a plug and jack. However, it is desirable to compensate for inductive cross talk as near to the source of the cross talk as possible, that is, as near to the plug and jack contacts as possible.  
         SUMMARY OF THE INVENTION  
         [0006]    An array of electrical conductors, the array including an input zone, a first inductive cross talk compensation zone downstream from the input zone, and a second inductive cross talk compensation zone downstream from the first inductive cross talk compensation zone, the first inductive cross talk compensation zone of the array being configured to induce corrective mutual inductance therein for reducing cross talk caused by undesirable mutual inductance in the input zone of the array, and the second inductive cross talk compensation zone of the array being configured to induce corrective mutual inductance therein for reducing cross talk caused by undesirable mutual inductance in the input zone of the array and caused by undesirable mutual inductance in the first inductive cross talk compensation zone of the array.  
           [0007]    A method for reducing undesirable inductive cross talk in an array of electrical conductors, the method including the steps of providing an array of electrical conductors, configuring the array to include an input zone, a first inductive cross talk compensation zone downstream from the input zone, and a second inductive cross talk compensation zone downstream from the first inductive cross talk compensation zone, configuring the first inductive cross talk compensation zone of the array to induce corrective mutual inductance therein for reducing cross talk caused by undesirable mutual inductance in the input zone of the array, and configuring the second inductive cross talk compensation zone of the array to induce corrective mutual inductance therein for reducing cross talk caused by undesirable mutual inductance in the input zone of the array and caused by undesirable mutual inductance in the first inductive cross talk compensation zone of the array.  
           [0008]    A method for reducing undesirable inductive cross talk in an array of electrical conductors, the method including the steps of providing an array of electrical conductors comprising an input zone, a first inductive cross talk compensation zone downstream from the input zone, and a second inductive cross talk compensation zone downstream from the first inductive cross talk compensation zone, inducing undesirable cross talk in the input zone of the array, inducing undesirable cross talk in the first inductive cross talk compensation zone of the array, inducing corrective mutual inductance in the first inductive cross talk compensation zone for reducing cross talk caused by undesirable mutual inductance in the input zone of the array, and inducing corrective mutual inductance in the second inductive cross talk compensation zone for reducing cross talk caused by undesirable mutual inductance in the input zone of the array and caused by undesirable mutual inductance in the first inductive cross talk compensation zone of the array.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a fragmentary and schematic top plan view of an array of four pairs of conductors oriented in the configuration utilized in a TIA specified plug;  
         [0010]    [0010]FIG. 2 is a fragmentary and schematic elevational view of a plug inserted into a jack comprising an array of two pairs of conductors configured in accordance with an embodiment of the invention;  
         [0011]    [0011]FIG. 3 is a fragmentary and schematic perspective view of an array of two pairs of conductors in a jack configured in accordance with an embodiment of the invention as viewed from the rear of the jack;  
         [0012]    [0012]FIG. 4 is a fragmentary and schematic perspective view of an array of two pairs of conductors in a jack configured in accordance with an embodiment of the invention as viewed from the rear of the jack;  
         [0013]    [0013]FIG. 5 is a schematic elevational view of an array of two pairs of conductors with vectors drawn between the members of each pair to illustrate the angles of mutual inductance exhibited by the pairs;  
         [0014]    [0014]FIG. 6 is a fragmentary and schematic elevational view of an array of four pairs of conductors in a jack configured in accordance with an embodiment of the invention;  
         [0015]    [0015]FIG. 7 is a fragmentary and schematic elevational view of the array shown in FIG. 6, with a facing area in the first inductive cross talk compensation zone of the array shaded;  
         [0016]    [0016]FIG. 8 is a fragmentary and schematic elevational view of the array shown in FIG. 6, with a facing area in the second inductive cross talk compensation zone of the array shaded;  
         [0017]    [0017]FIG. 9 is a fragmentary perspective view of an array of four pairs of conductors in a jack configured in accordance with a further embodiment of the invention; and  
         [0018]    [0018]FIG. 10 is a fragmentary elevational view of the array shown in FIG. 9. 
     
    
     DETAILED DESCRIPTION  
       [0019]    The closely spaced configuration of contacts formed by the four twisted pairs of conductors in a TIA specified plug is shown generally at reference numeral  10  in FIG. 1. In the illustrated and described embodiments of the invention, the standard known by those of ordinary skill in the art as TIA 568B is utilized. However, the invention may be implemented with equal effectiveness in connections designed in accordance with the standard known by those of ordinary skill in the art as TIA 568A, because, as is known by those of ordinary skill in the art, TIA  568 A only differs from TIA 568B by orienting the respective conductors comprising Pair  3  in TIA 568B where the respective conductors comprising Pair  2  in TIA 568B are oriented, and vice versa. Therefore, the utilization of TIA 568B herein is for purposes of illustration and not for purposes of limitation, and reference herein to “TIA specifications” refers to both TIA 568A and TIA 568B. Turning now to FIG. 1, in accordance with TIA 568B, Pair  1  ( 11 ) is comprised of conductor  4  ( 11  N) and conductor  5  ( 11  P), which have negative and positive polarity, respectively; Pair  2  ( 12 ) is comprised of conductor  1  ( 12 P) and conductor  2  ( 12 N), which have positive and negative polarity, respectively; Pair  3  ( 13 ) is comprised of conductor  3  ( 13 P) and conductor  6  ( 13 N), which have positive and negative polarity, respectively; and Pair  4  ( 14 ) is comprised of conductor  7  ( 14 P) and conductor  8  ( 14 N), which have positive and negative polarity, respectively. Since Pair  1  ( 11 ) is surrounded by Pair  3  ( 13 ), resulting capacitive and inductive couplings are present between them. Furthermore, resulting capacitive and inductive couplings exist between both Pair  1  ( 11 ) and Pair  3  ( 13 ) and the outer Pair  2  ( 12 ) and Pair  4  ( 14 ).  
         [0020]    In order to control cross talk, it is required that both capacitive and inductive coupling fields be compensated for those induced in the plug, and to a certain extent, in the jack. Capacitive compensation is discussed in the aforementioned Denkmann and Brownell patents, and inductive compensation has been performed typically using the PC board to which the jack is attached, as shown in the Pharney patent. The techniques set forth below will outline how to compensate for inductive cross talk and thus reduce inductive cross talk using various configurations of the contact array in a connector jack, and thus control the inductive couplings between all pairs simultaneously.  
         [0021]    Inductive coupling between differential pairs in a three dimensional space is quantified primarily by two fundamental properties. Those properties are the separation distance and the facing area between the pairs. Mutual inductance is directly proportional to the facing area and mutual inductance is inversely proportional to the distance between the facing area.  
         [0022]    In addition, the angle between the facing areas is another variable. When the angle between the facing areas is  00 , there is maximum mutual inductance. The mutual inductance becomes less as the angle is increased until the angle reaches 90°, at which point the mutual inductance becomes zero. Thus the mutual inductance is a function of the cosine of the angle between the facing areas.  
         [0023]    Since the inductance which results in cross talk arising in the plug and to a certain extent in the jack between Pair  1  ( 11 ) and Pair  3  ( 13 ) can be approximately 1.75 mH, one can create a facing set of loops in the contact array to offset these inductive couplings in the plug and to a certain extent within the jack. This is done by canceling the inductance using loops in the jack contact array. FIG. 2 illustrates an embodiment of a loop  15  within a jack  16  that has received a plug  17 , with the intersection of the jack  16  and the plug  17  defining an input zone  18 . This loop area will need to be made larger as the distance between the pairs increases.  
         [0024]    The rear view of a jack may offer more insight into the relationship of the area to distance, which is illustrated in FIG. 3 by two conductor pairs  30 ,  31  in close proximity with reference to length “L”, distance “D”, and height “H” dimensions. The positive polarity conductors  30 P,  31 P and negative polarity conductors  30 N,  31 N of each pair  30 ,  31  are designated. It is noteworthy that the pins shown in FIG. 3 need not be positioned in a uniform staggering arrangement; for example, see conductor pairs  32 ,  33 , and the positive polarity conductors  32 P,  33 P and negative polarity conductors  32 N,  33 N therein, illustrated in FIG. 4. The illustration in FIG. 4 may prove to give decreased cross talk levels and satisfy other physical requirements, however, length may have to be increased as height is decreased. In a situation wherein multiple pairs of transmission lines require compensation due to the introduction of a plug, an arrangement is possible to allow one level of inductive compensation in the jack between Pairs  1  ( 11 ) and  3  ( 13 ), as well as Pairs  2  ( 12 ) and  3  ( 13 ) and Pairs  3  ( 13 ) and  4  ( 14 ), while maintaining reduced cross talk levels between Pairs  1  ( 11 ) and  2  ( 12 ) and Pairs  1  ( 11 ) and  4  ( 14 ) with reduced inductive couplings. Embodiments of the invention that help accomplish these objectives are shown in FIGS.  6 - 10  and are discussed further below.  
         [0025]    Furthermore, adjustments of facing area allows all pairs to be compensated inductively simultaneously giving reduced levels of cross talk on all pairs. This can be accomplished by changing the direction or angle of the area vectors, as shown in FIG. 5. Therefore, as illustrated in contact array  40  shown in FIG. 6, should Pair  1  (conductors  11 N,  11 P) and Pair  3  (conductors  13 N,  13 P) require −1.75 mH and Pairs  1  ( 11 N,  11 P) and  2  (conductors  12 N,  12 P) and Pairs  1  ( 11 N,  11 P) and  4  (conductors  14 N,  14 P) require +0.105 mH, loops can be created with Pairs  1  ( 11 N,  11 P) and  3  ( 13 N,  13 P) maintained at −1.75 mH. Pairs  3  ( 13 N,  13 P) and  2  ( 12 N,  12 P) and Pairs  3  ( 13 N,  13 P) and  4  ( 14 N,  14 P) can then be controlled for inductive compensation of the plug via adjusting the shaded area shown at reference numeral  50  in FIG. 7, which falls within a first inductive compensation zone “A” in the contact array  40 . Controlling Pairs  1  ( 11 N,  11 P) and  2  ( 12 N,  12 P) and Pairs  1  ( 11 N,  11 P) and  4  ( 14 N,  14 P) can then be made by adjusting the area shown at reference numeral  51  in FIG. 8, which falls within a second inductive compensation zone “B” in the contact array  40 .  
         [0026]    Conductors  14 P and  12 P can be raised or lowered to give the correct inductive coupling value to compensate the inductive cross talk in the plug. Using this approach, near ideal inductive compensation can be induced between all pair combination to reduce cross talk levels between pairs for connecting hardware.  
         [0027]    [0027]FIGS. 9 and 10 illustrate a contact array  60  to accomplish the above, with Pairs  1  ( 11 N,  11 P),  2  ( 12 N,  12 P),  3  ( 13 N,  13 P), and  4  ( 14 N,  14 P), as well as first and second inductive compensation zones “A”, “B” referenced therein.  
         [0028]    An electrical connector having a contact array which provides inductive cross talk compensation is described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation—the invention being defined by the claims.