Abstract:
A communication jack having crosstalk compensation features for overall crosstalk interference reduction is disclosed. In one embodiment, the jack is configured to receive a plug to form a communication connection, and comprises jack contacts disposed in the jack, with each contact having at least a first surface and a second surface. Upon the plug being received by the jack, the plug contacts interface with the first surface of the jack contacts. The jack further includes a first capacitive coupling connected between two pairs of jack contacts to compensate for near end crosstalk, with the first capacitive coupling being connected to the pairs of jack contacts along the second surface adjacent to where the plug contacts interface with the jack contacts. A far end crosstalk compensation scheme is also set forth.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/606,420, filed Sep. 7, 2012, which is a continuation of U.S. patent application Ser. No. 12/969,779, filed Dec. 16, 2010, which issued as U.S. Pat. No. 8,262,415 on Sep. 11, 2012, which is a continuation of U.S. patent application Ser. No. 12/272,127, filed Nov. 17, 2008, which issued as U.S. Pat. No. 7,874,879 on Jan. 25, 2011, which is a continuation of U.S. patent application Ser. No. 11/623,578, filed Jan. 16, 2007, which issued as U.S. Pat. No. 7,452,246 on Nov. 18, 2008, which is a continuation of U.S. patent application Ser. No. 11/055,344, filed Feb. 10, 2005, which issued as U.S. Pat. No. 7,179,131 on Feb. 20, 2007, which claims priority to U.S. Provisional Application Ser. No. 60/544,050, filed on Feb. 12, 2004; U.S. Provisional Application Ser. No. 60/558,019, filed on Mar. 31, 2004; and U.S. Provisional Application Ser. No. 60/559,876, filed on Apr. 6, 2004; the entireties of which are hereby incorporated by reference. In addition, this application is related in subject matter to copending U.S. patent application Ser. No. 11/014,097, filed Dec. 15, 2004; and copending U.S. patent application Ser. No. 11/078,816, filed Mar. 11, 2005. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to electrical connectors, and more particularly, to modular communication connectors that utilize compensation techniques to reduce net crosstalk generated by the combination of a plug and a jack of a connector assembly. 
       BACKGROUND 
       [0003]    Computer networks, including local area networks (LAN) and wide area networks (WAN), are becoming increasingly prevalent as the number of computers and network devices in the workplace grows. These computer networks utilize data communication cables and electrical connectors to transmit information between various components attached to the network. The electrical connectors are typically configured to include a plug that is connectable to a jack mounted in the wall, or integrated into a panel or other telecommunication equipment. The jack typically includes a housing that holds an array of closely spaced parallel contacts for contacting corresponding conductors of the plug. The contacts of a jack are often mounted onto a printed circuit board. An RJ45 plug and jack connector assembly is one well known standard connector assembly having closely spaced contacts. 
         [0004]    Over the past several years, advances in computer networking technology have facilitated a corresponding increase in the rate at which data can be transmitted through a network. Conventional connectors have been used to transmit low-frequency data signals without any significant crosstalk problems. However, when such connectors are used to transmit high-frequency data signals, crosstalk generated within the connector increases dramatically. This crosstalk is primarily due to the capacitive and inductive couplings between the closely spaced parallel conductors within the jack and/or the plug. 
         [0005]    A wide variety of improvements have been made in the design of electrical connectors to reduce crosstalk occurring within the connector. One example is disclosed in U.S. Pat. No. 6,305,950, which is commonly assigned to Panduit Corporation. This type of connector uses a particular conductor configuration in conjunction with a multi-layered printed circuit board containing capacitors to achieve a reduction in the crosstalk effect. However, due to the high level of crosstalk occurring in the plug for this connector at very high-frequency signal rates, the tuning effect achievable by the capacitors can still be difficult to accomplish. As such, further improvements in the design of connectors are still needed to address such problems and provide improved crosstalk performance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of a connector assembly embodying the principles of the present invention; 
           [0007]      FIG. 2  is a schematic diagram of the compensation technique to reduce crosstalk in the connector assembly of  FIG. 1 ; 
           [0008]      FIG. 3  is a NEXT schematic vector diagram of the connector assembly of  FIG. 1 ; 
           [0009]      FIG. 4  is a FEXT schematic vector diagram of the connector assembly of  FIG. 1 ; 
           [0010]      FIG. 5  is a perspective view of an electrical jack embodying the principles of the present invention; 
           [0011]      FIG. 6  is an exploded view of the electrical jack of  FIG. 5 ; 
           [0012]      FIG. 7  is a sectional view of the electrical jack of  FIG. 5  taken along line A-A of  FIG. 5 ; 
           [0013]      FIG. 8  is a plan view of the printed circuit board of the electrical jack of  FIG. 5 ; 
           [0014]      FIG. 9  is a plan view of an alternative printed circuit board of the electrical jack of  FIG. 5 ; 
           [0015]      FIG. 10  is a sectional view of the printed circuit board of  FIG. 9  taken along line A-A of  FIG. 9 ; 
           [0016]      FIG. 11  is a sectional view of the printed circuit board of  FIG. 9  taken along line B-B of  FIG. 9 ; 
           [0017]      FIG. 12  is a perspective exploded view of another electrical jack embodying the principles of the present invention; 
           [0018]      FIG. 13  is a sectional view of the electrical jack of  FIG. 12  taken along line B-B of  FIG. 12 . 
           [0019]      FIG. 14  is a perspective view of one embodiment of a flexible circuit capacitor; 
           [0020]      FIG. 15  is a bottom view of the flexible circuit capacitors attached to jack contacts, shown in the unformed state; 
           [0021]      FIG. 16  is a top view of the flexible circuit capacitor of  FIG. 14 ; 
           [0022]      FIG. 17  is a sectional view taken along line C-C of  FIG. 16 ; 
           [0023]      FIG. 18  is a sectional view taken along line D-D of  FIG. 16 ; 
           [0024]      FIG. 19  is a sectional view taken along line E-E of  FIG. 16 ; 
           [0025]      FIG. 20  is a perspective view of another embodiment of a flexible circuit capacitor; 
           [0026]      FIG. 21  is a top view of the flexible circuit capacitor of  FIG. 20 ; 
           [0027]      FIG. 22  is a sectional view taken along line F-F of  FIG. 21 ; 
           [0028]      FIG. 23  is a sectional view taken along line G-G of  FIG. 21 ; 
           [0029]      FIG. 24  is a sectional view taken along line H-H of  FIG. 21 ; 
           [0030]      FIGS. 25-27  are sectional views taken along lines F-F, G-G and H-H, respectively, of  FIG. 21 , showing the flexible circuit capacitor being connected to a contact; 
           [0031]      FIG. 28  is a perspective view of a flexible circuit capacitor according to one embodiment of the present invention; 
           [0032]      FIG. 29  is a top view of the flexible circuit capacitor of  FIG. 28 ; 
           [0033]      FIG. 30  is a sectional view taken along the line I-I of  FIG. 29 ; 
           [0034]      FIG. 31  is a sectional view taken along the line J-J of  FIG. 29 ; 
           [0035]      FIG. 32  is a sectional view taken along the line K-K of  FIG. 29 ; 
           [0036]      FIGS. 33-35  are sectional views of a flexible capacitor showing a solder rivet being attached to a jack contact; 
           [0037]      FIG. 36  is a perspective view of a jack contact capacitor according to one embodiment of the present invention; 
           [0038]      FIG. 37  is a perspective view of a jack contact capacitor with bent contact strips; 
           [0039]      FIG. 38  is a side view of the jack contact capacitor of  FIG. 36 ; 
           [0040]      FIG. 39  is a sectional view taken along the line L-L of  FIG. 38 ; 
           [0041]      FIG. 40  is a side cutaway view of the jack contact capacitor of  FIG. 36 ; 
           [0042]      FIG. 41  is a side cutaway view showing contact capacitors mounted to jack contacts in a sled in an unmated position; 
           [0043]      FIG. 42  is a side cutaway view of the contact capacitors mounted to jack contacts in a sled of  FIG. 41  showing the jack contacts in a mated position; 
           [0044]      FIG. 43  is a perspective view of a jack contact capacitor according to one embodiment of the present invention; 
           [0045]      FIG. 44  is a top view of the jack contact capacitor of  FIG. 43 ; 
           [0046]      FIG. 45  is a sectional view taken along the line M-M of  FIG. 44 ; 
           [0047]      FIG. 46  is a sectional view taken along the line N-N of  FIG. 44 ; 
           [0048]      FIG. 47  is a sectional view taken along the line O-O of  FIG. 44 ; 
           [0049]      FIG. 48  is a top view of jack contact capacitors attached to jack contacts; 
           [0050]      FIG. 49  is a side view of jack contact capacitors attached to jack contacts; 
           [0051]      FIG. 50  is a rear view of jack contact capacitors attached to jack contacts; 
           [0052]      FIG. 51  is a side cutaway view of jack contact capacitors attached to jack contacts in a sled in an unmated position; 
           [0053]      FIG. 52  is a side cutaway view of jack contact capacitors attached to jack contacts in a sled in a mated position; 
           [0054]      FIG. 53   a  is a perspective view showing jack contact capacitors of one embodiment of the present invention mounted to jack contacts; 
           [0055]      FIG. 53   b  is a perspective view showing jack contact capacitors according to one embodiment of the present invention; 
           [0056]      FIG. 54  is a detail view of the detail “P” of  FIG. 53   b;    
           [0057]      FIG. 55  is a side cutaway view showing jack contact capacitors attached to jack contacts mounted to a sled; 
           [0058]      FIG. 56  is a rear view of a jack-and-capacitor assembly according to the embodiment of  FIG. 53   a;    
           [0059]      FIG. 57  is a side cutaway view of an adhesive area of a jack contact capacitor connected to a jack contact; 
           [0060]      FIG. 58  is a perspective view of a flexible circuit according to one embodiment of the present invention; 
           [0061]      FIG. 59  is a plan view of a flexible shunt according to one embodiment of the present invention; 
           [0062]      FIG. 60  is a side view of the flexible shunt of  FIG. 59 ; 
           [0063]      FIG. 61  is a side view of a flexible shunt mounted between jack contacts and a printed circuit board; 
           [0064]      FIG. 62  is a sectional view taken along the line Q-Q of  FIG. 59 ; 
           [0065]      FIG. 63  is a perspective view of flexible circuit capacitors according to one embodiment of the present invention; 
           [0066]      FIG. 64  is a detail view of the detail “R” of  FIG. 63 ; 
           [0067]      FIG. 65  is a top view of a flexible circuit capacitor of  FIG. 63 ; 
           [0068]      FIG. 66  is a side view of a flexible circuit capacitor of  FIG. 63 ; 
           [0069]      FIG. 67  is a perspective view of a flexible circuit capacitor of  FIG. 63  attached to jack contacts; 
           [0070]      FIG. 68  is a perspective view of the flexible circuit capacitors of  FIG. 63  attached to jack contacts; 
           [0071]      FIG. 69  is a side view of the flexible circuit capacitors of  FIG. 63  attached to jack contacts; 
           [0072]      FIG. 70  is a rear view of the flexible circuit capacitors of  FIG. 63  attached to jack contacts; 
           [0073]      FIG. 71  is an end view showing the overlap of capacitive plates in a flexible circuit capacitor of  FIG. 63 ; 
           [0074]      FIG. 72  is a plan view showing the overlap of capacitive plates in a flexible circuit capacitor of  FIG. 63 ; 
           [0075]      FIG. 73  is a perspective view of a flexible printed circuit according to one embodiment of the present invention; 
           [0076]      FIG. 74  is a plan view of the flexible printed circuit of  FIG. 73 ; 
           [0077]      FIG. 75  is a sectional view taken along the line S-S of  FIG. 74 ; 
           [0078]      FIG. 76  is a sectional view taken along the line T-T of  FIG. 74 ; 
           [0079]      FIGS. 77-80  are plan views respectively showing conductive pathways associated with first, second, third, and fifth conductors of an eight-conductor jack; 
           [0080]      FIGS. 81-84  are perspective views progressively showing conductive pathways of the flexible printed circuit of  FIG. 73 ; 
           [0081]      FIG. 85  is a perspective view showing a dielectric layer according to one embodiment of the present invention; 
           [0082]      FIG. 86  is a plan view showing conductive pathways in the flexible printed circuit of  FIG. 73 ; 
           [0083]      FIG. 87  is a sectional view taken along the line U-U of  FIG. 86 ; 
           [0084]      FIG. 88  is a sectional view taken along the line V-V of  FIG. 86 ; 
           [0085]      FIG. 89  is a perspective view of a flexible circuit capacitor according to one embodiment of the present invention; 
           [0086]      FIG. 90  is a top view of the flexible circuit capacitor of  FIG. 89 ; 
           [0087]      FIG. 91  is a sectional view taken along the line W-W of  FIG. 90 ; 
           [0088]      FIG. 92  is a sectional view taken along the line X-X of  FIG. 90 ; 
           [0089]      FIG. 93  is a sectional view taken along the line Y-Y of  FIG. 90 ; 
           [0090]      FIG. 94  is a side view of the flexible circuit capacitor of  FIG. 89  showing a rivet attached to a jack contact; 
           [0091]      FIG. 95  is a side view of the flexible circuit capacitor of  FIG. 89  showing an adhesive area bonded to a jack contact; 
           [0092]      FIG. 96  is a perspective view of a NEXT compensation capacitor circuit according to one embodiment of the present invention; 
           [0093]      FIG. 97  is a plan view of conductive plates of the NEXT compensation capacitor circuit of  FIG. 96 ; 
           [0094]      FIG. 98  is an end view along the view line “Z” of  FIG. 97 ; 
           [0095]      FIGS. 99-104  are plan views of the interior of the NEXT compensation capacitor circuit of  FIG. 96  showing the shapes of conductive plates; 
           [0096]      FIG. 105  is a plan view of a flexible printed circuit according to one embodiment of the present invention; 
           [0097]      FIG. 106  is a sectional view taken along the line AA-AA of  FIG. 105 ; 
           [0098]      FIGS. 107-109  are perspective views showing successive layers of the flexible printed circuit of  FIG. 105 ; 
           [0099]      FIG. 110  is a side cutaway view showing flexible printed circuits of  FIG. 105  installed within a jack with jack contacts in an unmated position; 
           [0100]      FIG. 111  is a side cutaway view showing flexible printed circuits of  FIG. 105  installed within a jack with jack contacts in a mated position; 
           [0101]      FIG. 112  is a plan view of a flexible printed circuit according to another embodiment of the present invention; 
           [0102]      FIG. 113  is a perspective view of a flexible PCB according to one embodiment of the present invention; 
           [0103]      FIG. 114  is a side view of the flexible PCB of  FIG. 113 ; 
           [0104]      FIG. 115  is a front view of the flexible PCB of  FIG. 113 ; 
           [0105]      FIG. 116  is another front view of the flexible PCB of  FIG. 113  showing conductive pathways; 
           [0106]      FIG. 117  is an end view toward the line A/A of  FIG. 116 ; and 
           [0107]      FIGS. 118-121  are front views of the flexible PCB of  FIG. 113  showing, respectively, capacitive plates associated with fifth, third, sixth, and fourth conductors of an eight-conductor jack. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0108]    Before explaining the present embodiments in detail, it should be understood that the invention is not limited in its application or use to the details of construction and arrangement of parts illustrated in the accompanying drawings and description. It will be recognized that the illustrative embodiments of the invention may be implemented or incorporated in other embodiments, variations and modifications, and may be practiced or carried out in various ways. Furthermore, unless otherwise indicated, the terms and expressions employed herein have been chosen for the purpose of describing the illustrative embodiments of the present invention for the convenience of the reader and are not for the purpose of limitation. 
         [0109]    Referring now to the drawings, and more particularly to  FIG. 1 , a communication connector assembly  100  is illustrated. The communication connector assembly  100  includes a compensation technique that reduces net crosstalk in accordance with the principles of the present invention. As shown in  FIG. 1 , the communication connector assembly  100  includes a plug  102  that is connectable to a jack  104 . The jack  104  includes a housing  106  and a carrier portion to hold a printed circuit board (not shown). The housing  106  of the jack  104  holds an array of closely spaced parallel contacts for contacting corresponding contacts of the plug  102 . When electrical signals are transmitted through the communication connector assembly  100 , crosstalk occurs within the connector assembly. 
         [0110]    Crosstalk is primarily generated in the connector assembly due to the closely spaced parallel conductors within the plug  102  and the jack  104 . In general, cross-talk is a measure of undesirable signal coupling from one circuit pair to another. Several different measures of cross-talk have been developed to address concerns arising in communication connector assemblies. Near end crosstalk (NEXT) is a measurement of crosstalk traveling in the opposite direction as a disturbing signal in a different circuit pair. NEXT is calculated according to the following equation: NEXT=Signal Voltage due to (Capacitive Coupling (C)+Inductive Coupling (L)). Far end crosstalk (FEXT) is a measurement of crosstalk traveling in the same direction as a disturbing signal in a different circuit pair. FEXT is calculated according to the following equation: FEXT=Signal Voltage due to (Capacitive Coupling (C)−Inductive Coupling (L)). A further description of the principles of crosstalk within a connector is disclosed in U.S. Pat. No. 5,997,358 (the “358 patent”), which is hereby incorporated by reference. 
         [0111]    There is distributed inductive and capacitive coupling between all signal current carrying conductors in a plug/jack combination from the cable connection to the plug to the cable connection to the jack. In addition, there is capacitive coupling between any conductive materials which are remote from the above conductors and which are connected electrically to the above conductors and between the conductive materials and the above conductors. 
         [0112]    The major couplings which illustrate how a preferred embodiment functions are illustrated schematically in  FIG. 2 . 
         [0113]    The plug is primarily distributed inductive and capacitive coupling. 
         [0114]    The NEXT compensation zone is remote capacitive coupling. 
         [0115]    The jack contacts are primarily distributed inductive and capacitive coupling. 
         [0116]    The NEXT crosstalk zone is remote capacitive coupling. 
         [0117]    The FEXT crosstalk zone is a combination of distributed inductive and capacitive coupling and a remote capacitive coupling. 
         [0118]    The distinction between distributed couplings and remote couplings is important because of their different effects on NEXT and FEXT. 
         [0119]    NEXT is the reflected signal from any coupling back to the cable connection to the plug. The phase angle of each element of NEXT is dependent on the distance from said cable connection to and from said element. 
         [0120]    FEXT is the signal from any coupling that travels to the cable connection to the jack. Thus, all such signals from distributed couplings are in phase regardless of their location. The phase angle of the signal from each remote coupling is, however, dependent on the distance to and from the remote coupling to the current carrying conductors. 
         [0121]    In the illustrated embodiment, conductors 3,6 form one wire pair and conductors 4,5 form another wire pair. It will be recognized that different wire pair combinations and other wire pairs can be utilized without departing from the spirit and scope of the present invention. 
         [0122]    The compensation scheme of the connector assembly  100  includes a NEXT compensation scheme and a FEXT compensation scheme. The NEXT compensation scheme preferably includes a NEXT compensation zone and a NEXT crosstalk zone. The NEXT compensation scheme reduces the NEXT of the plug and the jack to effectively zero at a selected null frequency.  FIG. 3  is a vector representation of the NEXT compensation scheme implemented on the two wire pairs 3,6 and 4,5 according to the present invention. 
         [0123]    As shown in  FIG. 3 , the plug  102  of the connector assembly  100  introduces offending NEXT onto the circuit pairs of the connector assembly  100 . The offending NEXT of the plug  102  includes an inductive component from inductive coupling (Lp) and a capacitive component from capacitive coupling (Cp). In order to reduce the offending NEXT of the plug  102 , the NEXT compensation zone of the connector assembly  100  introduces a compensation component from capacitive coupling (C 2 ) on the circuit pairs of the connector. 
         [0124]    The magnitude of the capacitive coupling (C 2 ) is preferably greater than the magnitude of the couplings of the plug (Cp+Lp), but with opposite polarity. In this embodiment, the magnitude of the capacitive coupling (C 2 ) is approximately twice the magnitude of the offending couplings of the jack  104 . The magnitude of the resultant NEXT is dependent on the magnitude of the phase angle between the coupling of the plug and the capacitive coupling (C 2 ). The larger the phase angle, the larger the resultant NEXT. It is therefore desirable to minimize this phase angle. This phase angle is proportional to the distance between the effective center of the crosstalk coupling of the plug and the effective center of the NEXT compensation zone. 
         [0125]    As shown in  FIG. 3 , the NEXT compensation zone introduces a capacitive compensation coupling (C 2 ) on the circuit pairs of the jack to reduce the offending NEXT of the plug. As further described below, the NEXT compensation zone can be implemented in the jack  104  by connecting capacitors between selected jack contacts at or near but on the opposite sides of the electrical interface  110  of the jack  104  contacts and the plug  102  contacts. As a result, the phase angle between the offending NEXT of the plug and the compensation component introduced by the NEXT compensation zone is minimized. The capacitors of the NEXT crosstalk zone are connected between circuit paths 3 and 5, and 4 and 6 at or near the electrical interface  110  of the jack contacts and the plug contacts. 
         [0126]    Referring again to  FIG. 3 , the jack contacts of the connector assembly  100  introduce couplings onto circuit pairs of the connector assembly. The couplings of the jack contacts include an inductive component (L 1 ) and a capacitive component (C 1 ). 
         [0127]    The NEXT crosstalk coupling (C 3 ) has the same polarity as the coupling of the plug  102 , but has the opposite polarity of the capacitance compensation coupling (C 2 ). The NEXT crosstalk zone is located at a particular phase angle at the null frequency from the NEXT compensation zone. In the preferred embodiment, since the phase angle between the coupling of the plug and the capacitive coupling (C 2 ) of the NEXT compensation zone is relatively small, the phase angle between the capacitive coupling (C 2 ) of the NEXT compensation zone and the capacitive coupling (C 3 ) of the NEXT crosstalk zone is relatively small. In order to attain a relatively small phase angle between these capacitive couplings, the length of that portion of the jack contacts between the NEXT compensation zone and the NEXT crosstalk zone is relatively small. A preferred embodiment disclosed herein minimizes this length, separates them with air as much as feasible, and still provides adequate force between the jack contacts and the contacts of an installed plug. 
         [0128]    As shown in  FIG. 2 , the NEXT crosstalk zone introduces the crosstalk coupling (C 3 ) on the circuit paths of the connector. The NEXT crosstalk zone is preferably located at a particular phase angle at the null frequency from the cable connection to the plug. As further described below, the NEXT crosstalk zone can be implemented in the jack  104 , for example, by connecting capacitors between the input terminals of the printed circuit board (PCB) of the connector assembly  100 . It will also be recognized that such capacitors could be connected between the contacts of the jack  104  at the same locations that the NEXT compensation zone capacitors are connected. They would, however, be connected between different conductors to reverse the polarity, and the length of the electrical conductors from the connection point to the NEXT crosstalk zone capacitors would be larger than the length of the electrical conductors from the connection point to the NEXT compensation zone capacitors. 
         [0129]    The NEXT crosstalk zone capacitors could alternatively be connected to the jack contacts between the plug/jack contact interface and the cable connection to the jack. As shown in  FIG. 2 , the crosstalk coupling (C 3 ) of the NEXT crosstalk zone is introduced by capacitors whose leads are connected between circuit paths 3, 4 and 5, 6 at the input terminals of the PCB. 
         [0130]    As further described below, the FEXT crosstalk zone includes a crosstalk coupling (C C ) and compensation couplings (L FCZ  and C L ). The location of the effective center of the compensation couplings (L FCZ  and C L ) and the effective center of the crosstalk coupling (C C ) of the FEXT crosstalk zone are preferably equidistant and equal in phase angle displacement from the electrical interface of the plug and jack. The NEXT components generated by capacitive coupling in the FEXT crosstalk zone are generated by C C  and C L  and the net of these couplings is C FCZ  which is equal to C C -C L . The inductive compensation coupling in the FEXT crosstalk zone (L FCZ ) is preferably equal in magnitude and of opposite polarity to the crosstalk component (C FCZ ). As a result, since NEXT coupling is equal to C+L, the two components (L FCZ ) and (C FCZ ) will cancel each other out, and therefore, the FEXT crosstalk zone has little or no effect on NEXT. 
         [0131]    Referring to  FIG. 4 , couplings C and L for a specification plug both create crosstalk which is designated as negative (−). 
         [0132]    In this jack design, the jack contacts have couplings C and L which both create crosstalk and which are also negative (−). 
         [0133]    As previously stated, NEXT is equal to the signal voltage due to couplings C+L and FEXT is equal to the signal voltage due to couplings C−L. 
         [0134]    Therefore, the net effect of the couplings due to the plug and the jack contacts is greatly reduced in their effect on FEXT compared to their effect on NEXT. Since the combined effects of the various couplings are extremely successful in minimizing NEXT, the same couplings result in an excessive FEXT. 
         [0135]    However, although the net effect of the FEXT crosstalk zone is zero on NEXT, it has a beneficial effect of reducing FEXT. 
         [0136]    In the example of the embodiment taught herein, the net capacitive coupling of the FEXT crosstalk zone is C FCZ  and it is crosstalk and has a negative (−) sign. 
         [0137]    The inductive coupling of the FEXT crosstalk zone is L FCZ  and it is compensation and has a positive sign (+). 
         [0138]    The couplings that affect NEXT=C FCZ +L FCZ =−0.944 pF+0.948 pF*=0 
         [0139]    The couplings that affect FEXT=C FCZ −L FCZ =−0.946 pF−0.946 pF*=1.892 pF *Equivalent pF to nH of L FCZ    
         [0140]    The magnitude of the net effect of the FEXT crosstalk zone on FEXT has been derived to be approximately equal to the loss of the net effect of the plug and jack contacts on FEXT compared to their effect on NEXT. 
         [0141]    In the creation of FEXT, the phase angle displacement between the various elements is equal to two times the distance (in Phase Angle Displacement) from the signal path to the elements. In this embodiment, these phase angles are relatively small, and therefore the FEXT is relatively small. 
         [0142]    The inductive coupling portion of the FEXT crosstalk zone, L FCZ  is created by adjacent current carrying conductors on the PCB. It is not a design objective, but these conductors produce a minimal amount of capacitive coupling in addition to the inductive coupling. Both of these couplings have a polarity which is opposite to that of the couplings in the plug and which has been designated as positive. The designation of this capacitive coupling is C L . 
         [0143]    The main capacitive coupling portion of the FEXT crosstalk zone is created by capacitor plates which are an integral part of the PCB and which are connected by conductors to the current carrying conductors in the above described inductive coupling portion. The connecting conductors are connected at a selected location and are of a selected length to insure the phase angle displacement from the plug/jack contact interface is equal for L FCZ  and C FCZ . The polarity of this capacitive coupling is negative, the same as the couplings in the plug. 
         [0144]    The designation of this capacitive coupling is C C . 
         [0145]    The magnitude of C C  is such that C C −C L =C FCZ =Equivalent to magnitude of L FCZ  in pF. 
         [0146]    Referring to  FIG. 2 , FEXT is the signal from any coupling that travels to the cable connection to the jack. Thus, all such signals from distributed couplings are in phase regardless of their location. The phase angle of the signal from each remote coupling is, however, dependent on the distance to and from the remote coupling to the current carrying conductors. 
         [0147]    Again, referring to  FIG. 4 , as compared to  FIG. 3 , the net plug vector is reduced in magnitude. The net jack contact vector is reduced in magnitude. The three components of the FEXT crosstalk zone no longer add up to zero. They are now effective. 
         [0148]    Referring to  FIG. 4 , all the distributed couplings are in phase with each other and all the remote couplings have a phase angle which is lagging the distributed couplings. 
         [0149]    The FEXT crosstalk zone can be implemented in the printed circuit board of the jack by connecting selected magnitudes of capacitance between circuit paths and by creating mutual inductance between adjacent circuit paths. The inductive couplings of the FEXT crosstalk zone are generated in the printed circuit board by positioning circuit paths 3 and 5 in close proximity to each other for a selected distance, and positioning circuit paths 4 and 6 in close proximity to each other for a selected distance. As shown in  FIG. 8 , capacitors are connected between pairs 3,6 and 4,5 at a selected distance from the input terminals of the printed circuit board. 
         [0150]    The NEXT generated by the FEXT crosstalk zone is self-canceling as described above. The effects of couplings on FEXT are determined by distributed couplings and by remote couplings in the same manner regardless of their positioning along signal paths. Therefore, the FEXT crosstalk zone can be positioned at any suitable distance from the NEXT compensation zone, without degrading NEXT or FEXT performance. 
         [0151]    The plug is a specification plug which must be used and it contains inductive and capacitive coupling. 
         [0152]    The contacts are designed to be short in length and mechanically sound. The result is that they contain inductive and capacitive crosstalk coupling. Longer and more complicated contacts could be designed to have minimal inductive coupling or inductive compensation coupling however such complications would not enhance the superior results of this invention. 
         [0153]    The NEXT compensation zone design provides the minimum phase angle change from the interface of the plug/jack contacts to the effective center of the NEXT compensation zone. The NEXT compensation zone coupling is all capacitive because simple alternate designs with inductive coupling would increase the phase angle change. The NEXT compensation zone design allows minimum NEXT to be achieved and it is one of the most important elements of this invention. 
         [0154]    The NEXT crosstalk zone provides only capacitive coupling. This is the optimum design because it provides the required balance to minimize NEXT and it has no detrimental affect on FEXT. 
         [0155]    The results of the above design are: 
         [0156]    It provides minimum NEXT; and 
         [0157]    It provides relatively large FEXT. 
         [0158]    This combination of results creates a problem, however the addition of the FEXT crosstalk zone solves this problem because it has no effect on NEXT and has a very beneficial effect on FEXT. 
         [0159]    The FEXT crosstalk zone is also one of the most important elements of this invention and in combination with the unique compensation zone, the synergy results in a very important technical achievement. 
         [0160]    The parameters of the FEXT crosstalk zone design provided herein results in a relatively small FEXT; however, it is contemplated that the FEXT could be reduced further by changing design parameters. 
         [0161]    One example is to increase C L  which could be achieved by locating conductor 3 above 5 instead of adjacent to it and by locating conductor 6 above 4 instead of adjacent to it. With C L  increased, C C  would necessarily be increased. Since the phase angle of C C  is more nearly 180° from the NEXT compensation zone C 2  than C C , FEXT would be reduced. 
         [0162]    Another example is to increase the length of conductors 3,5 and 4,6 in combination with separating them to keep L FCZ  the same. Since C C  must be in the center of the FEXT crosstalk zone, the distance from the current paths to the remote C C  would necessarily be increased and this would change its phase angle which could be made optimum. 
         [0163]    In one embodiment, the parameters of the components of the compensation scheme implemented by the connector assembly are provided as follows: 
         [0164]    Plug: 
         [0000]        Cp+Lp =Equivalent to −1.472 pF
 
         [0000]        Cp−Lp =Equivalent to −0.111 pF
       where Lp is the inductive coupling of standard plug and Cp is the capacitive coupling of standard plug.       
 
         [0166]    Jack Contacts: 
         [0000]        C 1+ L 1=Equivalent to −0.791 pF
 
         [0000]        C 1− L 1=Equivalent to −0.071 pF
       where L 1  is the inductive coupling of jack contacts and C 1  is the capacitive coupling of jack contacts.       
 
         [0168]    NEXT Compensation Zone: 
         [0169]    If the effect of the jack contacts are ignored at 500 MHz null frequency, then C 2 =2.782 pF; however, with adjustments for jack contacts: 
         [0000]        C 2=3.574 pF       where C 2  is the capacitive coupling of NEXT compensation zone.         
         [0171]    NEXT Crosstalk Zone: 
         [0000]        C 3=−1.472 pF
       where C 3  is the capacitive coupling of NEXT crosstalk zone.       
 
         [0173]    FEXT Crosstalk Zone: 
         [0000]        C   FCZ =−0.944 pF
 
         [0000]      − L   FCZ =+1.741 nH=Equivalent to +0.944 pF
 
         [0000]        C   C =−1.138 pF
 
         [0000]      − C   L =+0.194 pF
       where:
           L FCZ  is the inductive coupling of FEXT crosstalk zone;   C FCZ  is the net capacitive coupling of FEXT crosstalk zone capacitors;   
               
 
         [0000]        C   FCZ   =C   C   −C   L ;           C L  is the capacitive coupling of FEXT crosstalk zone inductive coupling conductors; and   C C  is the capacitive coupling of FEXT crosstalk zone capacitors.             
         [0179]    As will be recognized by those skilled in the art, the values of the components of the compensation scheme may be varied in magnitude about their initially determined values for purposes of fine tuning. Although the embodiment has been applied to pairs 3,6 and 4,5 of a connector assembly, it will be recognized that the principles described herein can be applied to other pair combinations of an electrical connector, such as a jack. 
         [0180]    Referring now to  FIGS. 5-7 , an electrical connector implementing a compensation scheme to reduce crosstalk according to the present invention is shown. The electrical connector is preferably a jack  200 . The jack  200  minimizes the phase angle delay for introducing crosstalk compensation by introducing it at the plug/jack contact interface where the offending crosstalk is introduced to a jack by a mating plug (not shown). 
         [0181]    As shown in  FIGS. 5-7 , the jack  200  includes a housing  202  defining a plug receiving opening  204 , a PCB and conductor carrying sled  206  and a wire containment cap  208 . In the illustrated embodiment, the jack  200  is an 8 contact type (i.e., 4 twisted pair) connector arrangement according to a wire pair industry standard (i.e., wires 4 and 5 comprising pair 1, wires 3 and 6 comprising pair 2, wires 1 and 2 comprising pair 3, and wires 7 and 8 comprising pair 4). It is contemplated that the jack can be any other type of suitable jack or connector. 
         [0182]    The contact carrier  206  of the jack  200  includes a printed circuit board (PCB)  210  and a plurality of contacts  220 . The contacts  220  each have a first end portion  222  fixedly attached to the printed circuit board  210  and a second free end portion  224 . Each contact  220  also has a contact portion  226  extending between its first and second end portions  222 ,  224 . When a plug is inserted into the opening  204  of the housing  202 , the contact portions  226  of the connector  200  make electrical contact with the contacts of the plug. 
         [0183]    As described above, the plug introduces offending NEXT onto the jack conductors at the electrical interface of the contacts  220  and the plug. As part of the compensation for the offending NEXT of the plug, the jack  200  introduces a capacitive compensation coupling (C 2 ) at said electrical interface. As shown in  FIGS. 6 and 7 , the capacitance compensation coupling (C 2 ) of the NEXT compensation zone is preferably provided by flexible printed circuit capacitors  230  and  232  that are connected with flexible arms to the underside of the contact portions  226  of the contacts  220 . 
         [0184]    In the illustrated embodiment, the capacitors  230  and  232  are connected across contacts  220  associated with wire pair 1 (wires 3 and 5) and wire pair 2 (wires 4 and 6). The capacitors  230  and  232  are installed by electrically connecting flexible printed circuit capacitive plates to the respective contacts  220 . It will be recognized that the capacitors can be implemented by any suitable capacitive element. Since the capacitance compensation component (C 2 ) is connected at said plug/jack contact interface and since the distance from said plug/jack contact interface to the effective center of the capacitors is minimized, the phase angle between the offending NEXT of the plug and the NEXT compensation coupling (C 2 ) is minimized. 
         [0185]    Referring now to  FIG. 8 , a preferred layout of the circuit conductors or traces in the printed circuit board  210  of the jack  200  is shown. The printed circuit board  210  has a front portion  250  and a rear portion  252 . The front portion  250  includes a plurality of front terminals  260  labeled  1 - 8  and the rear portion  252  of the printed circuit board  210  includes a plurality of rear terminals  262  labeled 1-8. For explanation purposes, only the circuit pathways formed between front terminals  260  (labeled 3-6) and the rear terminals  262  (labeled  3 - 6 ) at the rear portion  252  are shown. Insulation displacement contacts (IDCs)  270  are mounted to each of the rear terminals  262  as shown in  FIG. 6 . The IDCs  270  are electrically connected through the circuit paths on the printed circuit board  210  to the front terminals  260 . 
         [0186]    Following the teachings of the &#39;358 patent, the jack  200  introduces a crosstalk or reverse compensation coupling (C 3 ) at specific locations on the circuit paths of the connector  200  at the NEXT crosstalk zone. The capacitance compensation component C 3  of the NEXT crosstalk zone of the jack  200  is introduced by capacitors  280  and  282  as shown in  FIG. 8 . 
         [0187]    The capacitors  280  and  282  are connected across front terminals 3, 4 and terminals 5, 6, respectively, of the printed circuit board  210  of the jack  200  and are preferably formed by parallel conductive plates. It will be recognized that the capacitors  280  and  282  can be discrete components, such as a capacitor, or any other suitable capacitive element. For example, the capacitors can be formed on the same or different layers of the circuit board and the shape or type of the capacitors can be varied. 
         [0188]    The printed circuit board  210  of the jack  200  implements a FEXT crosstalk scheme or zone to reduce or cancel the FEXT of the plug/jack combination. 
         [0189]    The FEXT compensation scheme introduces a crosstalk capacitive coupling (C C ) and inductive and capacitive compensation couplings (L FCZ  and C L ) onto the circuit paths of the printed circuit board  210 . The capacitance compensation coupling C C  of the FEXT crosstalk zone is introduced by capacitors  290  and  292 , and the compensation couplings (L FCZ  and C L ) are created by positioning the current carrying circuit paths in close proximity to each other. It is to be noted that the thickness or the cross-sectional dimension of the traces as well as the distance or spacing between the conductors or traces can also be adjusted to achieve the required couplings. 
         [0190]    As shown in  FIG. 8 , the capacitors  290  and  292  are connected across terminals 3, 5 and 4, 6, respectively, near the front terminals of the printed circuit board  210  of the jack  200 . Each of capacitors  290  and  292  are preferably formed by parallel conductive plates, but can be implemented by any suitable capacitor element. 
         [0191]    The locations of the effective center of the compensation couplings (L FCZ  and C L ) and the effective center of the capacitance crosstalk coupling (C C ) of the crosstalk zone are preferably equidistant and equal in phase angle displacement from the electrical interface of the plug and jack. 
         [0192]    It should be noted that the generation of the inductive compensation coupling (L FCZ ) introduces a capacitive coupling (C L ) having the same polarity as the inductive coupling (L FCZ ). However, the magnitude of the compensation coupling (C C ) is designed to cancel the C L  coupling out as well as the inductive coupling (L FCZ ) in the generation of NEXT. C FCZ =C C −C L . As a result, the compensation couplings (L FCZ  and C L ) are preferably equal in magnitude and of opposite polarity to the crosstalk component (C C ). Therefore, the two components (L FCZ ) and (C FCZ ) will cancel each out in the generation of NEXT. 
         [0193]    The IDCs have been designed so their effect on NEXT and FEXT is minimal. Their effect has been ignored. 
         [0194]    The layout illustrated in  FIG. 8  is effective in compensating for forward FEXT without adversely affecting forward NEXT (i.e. NEXT observed when the driven signal is received from the cable connection to the plug). Because the effective center of the compensation couplings (L FCZ  and C L ) and the effective center of the capacitance crosstalk coupling (C C ) of the crosstalk zone are designed to be equidistant from the electrical interface of the plug and jack, the resultant inductive and capacitive coupling vectors of the FEXT crosstalk zone are at the same phase angle location with regard to their effect on forward NEXT. 
         [0195]    For reverse NEXT (i.e. NEXT observed when the driven signal is received through the IDCs from a cable connection to the end of the jack opposite the plug), the effective center of the compensation couplings (L FCZ  and C L ) and the effective center of the capacitance crosstalk coupling (C C ) of the crosstalk zone will not be equidistant from the electrical interface of the plug and jack. This is due to the physical asymmetries in the trace layout of  FIG. 8 , caused by the use of remote capacitive couplings  290  and  292 . As a result, the inductive and capacitive coupling vectors of the FEXT crosstalk zone will be at different phase angle locations, adversely affecting reverse NEXT. 
         [0196]      FIG. 9  is a plan view of a layout for an alternative PCB  550  having couplings that are symmetrical from either direction, thereby providing FEXT compensation without adversely affecting forward or reverse NEXT. The PCB  550  includes a front portion  552  and a rear portion  554 . The front portion  552  includes a plurality of front terminals  560  labeled  1 - 8  and the rear portion  554  includes a plurality of rear terminals  562  labeled 1-8. As was the case for  FIG. 8 , only the circuit pathways between front terminals (labeled 3-6) and rear terminals (labeled 3-6) are shown. In addition, the NEXT crosstalk zone has been omitted from  FIG. 9  for clarity. 
         [0197]    Like the PCB  210  of  FIG. 8 , the FEXT crosstalk zone of PCB  550  utilizes distributed inductive couplings (i.e. where traces are placed in close horizontal or vertical proximity to one another). However, unlike the PCB  210 , which used remote capacitive couplings (parallel-plate capacitors  290  and  292 ), the PCB  550  utilizes distributed capacitive couplings  590 , which take the form of partially overlapping traces widened to approximate distributed parallel plates. As a result, the coupling vectors are at the same phase angle location with regard to their effect on both forward and reverse NEXT. Thus, the FEXT compensation zone benefits FEXT while being neutral to both forward and reverse NEXT. 
         [0198]      FIGS. 10 and 11  are sectional views of the PCB  550  taken along lines A-A and B-B, respectively, of  FIG. 9 . The traces corresponding to traces 3, 4, 5, and 6 are shown to each traverse one of four internal layers of the PCB  550 . This stratification provides spacing for desired capacitive and inductive coupling effects to appropriate FEXT compensation. 
         [0199]    While  FIGS. 9-11  illustrate one possible implementation of a symmetrical FEXT compensation zone, other implementations may also be used without departing from the intended scope of the invention. For example, different lengths and arrangements of traces may be used. Similarly, different shapes and configurations for distributed capacitances may be adopted. 
         [0200]    Referring now to  FIGS. 12 and 13 , another electrical connector  300  implementing the same compensation scheme to reduce NEXT and FEXT according to the present invention is shown. The electrical connector  300  is substantially similar to the previously described electrical connector  200 , except that the connection arrangement between the jack and the cable to which it is connected is a “punch down” design. Components of the electrical connector  300  which generally correspond to those components of the electrical connector  200  of  FIG. 5  are designated in the three-hundred series. As such, further description of the electrical connector  300  is unnecessary for a complete understanding of the present invention. 
         [0201]    The method and apparatus of the present invention provide a compensation technique to cancel or reduce the NEXT and FEXT produced by the electrical connector. In particular, the compensation scheme introduces compensation and crosstalk couplings into the electrical paths of the electrical connector to reduce or cancel the net crosstalk generated by the plug/jack combination. 
         [0202]    In the illustrated embodiment, the capacitors  230  and  232  are connected across contacts  220  associated with wire pair 1 (wires 3 and 5) and wire pair 2 (wires 4 and 6). The capacitors  230  and  232  are installed by electrically connecting flexible printed circuit capacitive plates to the respective contacts  220 . It will be recognized that the capacitors can be implemented by any suitable capacitive element. Since the capacitance compensation component (C 2 ) is connected at said interface and since the distance from said interface to the effective center of the capacitors is minimized, the phase angle between the offending NEXT of the plug and the NEXT compensation coupling (C 2 ) is minimized. 
         [0203]      FIGS. 14-19  illustrate one embodiment of the flexible printed circuit capacitors. These flexible circuit capacitors are made, for example, from a plated film of KAPTON® polyimide film manufactured by DuPont. The capacitors  230  and  232  include a pair of dome-shaped rivets and are attached opposite the plug/jack contact interface via electrical resistance or spot welding. 
         [0204]      FIGS. 20-27  illustrate a second embodiment of the flexible printed circuit capacitors  230  and  232 . These capacitors include a solder “plug”  236  and are attached to the contacts  220  that may include a pre-tinned area  238 . 
         [0205]      FIGS. 28-121  illustrate additional embodiments of capacitors according to the present invention.  FIG. 28  shows a flexible circuit capacitor  400  having solder rivets  402 . The solder rivets  402  are pre-formed and mechanically deformed into holes provided at the ends of the capacitor  400 . The flexible circuit capacitor  400  attaches to jack contacts by a resistance weld process.  FIG. 29  is a top view of the flexible circuit capacitor  400 , and  FIGS. 30 ,  31 , and  32  are, respectively, cross-sectional views taken along the lines I-I, J-J, and K-K of  FIG. 29 . As shown in  FIG. 30 , the solder rivet  402  is inserted in a plated through hole  404 . The plated through hole  404  is provided with pads. The rivet  402  has a dome head  406  (shown in  FIG. 31 ), and the rivet  402  is mechanically deformed on the underside as shown in  FIGS. 30 and 32 . 
         [0206]      FIGS. 33 ,  34 , and  35  are cross-sectional views of a flexible circuit capacitor  400  with a solder rivet  402  being attached to a jack contact  408 . As shown in  FIG. 33 , the jack contact  408  may be provided with a pre-tinned region  410  tinned with solder. The flexible circuit capacitor  400  is brought together with the jack contact  408  as shown in  FIG. 34  so that the solder rivet  402  makes physical contact with the pre-tinned region  410 . Then, as shown in  FIG. 35 , a welding tool  412  welds the rivet  402  to the contact  408 , for example by resistance welding. The welding may be performed simultaneously on several rivet-contact interfaces. The centerline  412   c  shown in  FIG. 35  is preferably located at the plug/jack contact interface. 
         [0207]      FIG. 36  shows an alternative PCB-type jack contact capacitor  413 . The jack contact capacitor  413  can serve as a NEXT compensation zone. In this embodiment, a printed circuit board  414  has contact strips  416  attached to it at eyelets  418 . Contact mating areas  420  are also provided on the contact strips  416  for attachment, for example via welding, to contacts of a jack. A similar construction is shown in  FIG. 37 , with the contact strips  416  bent for alternative mounting of the contact capacitor to a contact.  FIG. 38  is a side view of the jack contact capacitor  413  of  FIG. 36 , and  FIG. 39  is a cross-sectional view taken along the line L-L of  FIG. 38 . 
         [0208]    The cross-sectional view of  FIG. 39  shows the contact strip  416  held in place by the eyelet  418  and in electrical contact with a plated through hole  422 . Conductors  424  are also in contact with the plated through hole  422  and allow capacitive coupling between contact strips  416  within a printed circuit board  414 .  FIG. 40  shows a side cutaway view illustrating varying widths of the conductors  424  within the printed circuit board  414 . 
         [0209]      FIGS. 41 and 42  are side views of contact capacitors mounted to jack contacts  408  provided in a sled  426 . The printed circuit boards  414  of the jack contact capacitors fit within capacitor guides  428  of the sled  426 . A sled-mounted printed circuit board  430  may be provided within the sled  426 .  FIG. 41  shows the jack contacts  408  not mated to a plug and  FIG. 42  shows the jack contacts  408  bent downwardly as they would be bent when mated to a plug. A centerline  430   c  shows the plug/jack contact interface. The contact strips  416  are welded to the contacts  408  directly beneath the plug/jack contact interface, along the centerline  430   c.    
         [0210]    Turning now to  FIG. 43 , another embodiment of a jack contact capacitor  432  for implementing a NEXT compensation zone is shown. In the embodiment of  FIG. 43 , a flexible printed circuit  434  is adapted for connection to jack contacts via rivets  436   a  and  436   b . The rivets  436   a  and  436   b  are preferably provided with domed heads.  FIG. 44  is a top view of the jack contact capacitor  432 , and  FIGS. 45-47  are, respectively, cross-sectional views taken along the lines M-M, N-N, and O-O of  FIG. 44 . As shown in  FIG. 45 , a plated through hole  438  allows for electrical connection between a first rivet  436   a  and a first conductive plate  440 . Further, as shown in  FIG. 47 , another plated through hole  438  allows for electrical connection between a second rivet  436   b  and a second conductive plate  442 .  FIG. 46  shows a cross-sectional view of a region of capacitive coupling between the first conductive plate  440  and the second conductive plate  442 . 
         [0211]      FIGS. 48-50  show jack contact capacitors  432   a  and  432   b  attached to jack contacts  408 .  FIG. 48  is a top view of jack contacts  408  attached to jack contact capacitors  432   a  and  432   b , and  FIG. 49  is a side view of the assembly of  FIG. 48  and  FIG. 50  is a rear view of the assembly of  FIG. 48 . Contacts 3, 4, 5, and 6 of an eight-contact jack are shown. A centerline  442   c  of the welding between the jack contacts  408  and the jack contact capacitors  432   a  and  432   b  aligns with a plug/jack contact interface. The jack contact capacitors  432   a  and  432   b  are welded to the jack contacts  408  at a side opposite the plug/jack contact interface. Jack contact capacitors  432   a  and  432   b  can be attached to jack contacts  408  and mounted within a sled  426  as shown in  FIGS. 51 and 52 .  FIG. 51  shows the position of jack contacts  408  when a plug is not mated to the jack contacts  408  and  FIG. 52  shows the position of jack contacts mated with a plug. A printed circuit board  430  may be provided within the sled  426 . Capacitor guides  428  are positioned to accept the jack contact capacitors  432   a  and  432   b.    
         [0212]    Another embodiment of a jack contact capacitor is shown in  FIGS. 53   a - 56 . According to this embodiment of the present invention, jack contact capacitors  444   a  and  444   b  are adhesively mounted to jack contacts  408 .  FIG. 53   a  shows jack contact capacitors  444   a  and  444   b  mounted to jack contacts  408 . Jack contacts 3, 4, 5, and 6 of an eight-contact jack are shown.  FIG. 53   b  shows the jack contact capacitors  444   a  and  444   b  separated from the jack contacts  408 , and  FIG. 54  is a detail view of the detail “P” of  FIG. 53   b . As shown in  FIG. 54 , adhesive areas  446  are provided on contact strips  416  of the jack contact capacitors  444   a  and  444   b . The adhesive areas  446  allow for an adhesive connection to be made between the jack contact capacitors  444   a  and  444   b  and the jack contacts  408 . The resulting assembly can be mounted on a sled  426  as shown in  FIG. 55 , with capacitor guides  428  accepting the jack contact capacitors  444   a  and  444   b . The adhesive areas  446  are located directly beneath a plug/jack contact interface.  FIG. 56  is a rear view of a jack-and-capacitor assembly according to this embodiment of the invention. 
         [0213]    According to one embodiment, the jack contact capacitors  444   a  and  444   b  are formed with flexible printed circuits  448 , as shown in  FIG. 54 .  FIG. 57  shows a side cutaway view of an adhesive area  446  of a jack contact capacitor  444  connected to a jack contact  408 . Adhesive  450  is placed between a first dielectric layer  452 , such as a layer of MYLAR® PET film manufactured by DuPont, and a jack contact  408 . A conductor pattern  454  is layered between the first dielectric layer  452  and a second dielectric layer  456 . The conductor pattern  454  is layered between the first and second dielectric layers  452  and  456  in a flexible printed circuit  448 . The jack contact capacitors  444   a  and  444   b  are adhesively bonded to alternate jack contacts. For example, jack contact capacitor  444   a  may be bonded to jack contact pair 3-5 and jack contact capacitor  444   b  may be bonded to jack contact pair 4-6. This construction creates a capacitor by means of the conductor material  454  in the laminate form and the contact  408  itself. Two contacts are then coupled by two capacitors in series. Total capacitance between contacts is ½ the value of each capacitor. The thickness and dielectric constant of the adhesive are included in the calculations. 
         [0214]      FIGS. 58-61  show a NEXT compensation zone and flexible circuit contact shunt according to one embodiment of the present invention. A flexible NEXT compensation circuit  458  comprises a capacitor flexible circuit  460  adapted to connect to jack contacts via contact weld rivets  462  and further adapted to make electrical contact with a printed circuit board via printed-circuit-board compliant pins  464 . In the embodiment shown in  FIG. 58 , capacitive coupling between two contacts may be accomplished within a capacitor flexible circuit  460 . Turning to  FIG. 59 , a flexible shunt  466  is shown. The flexible shunt  466  is provided with rivets  462  on flexible members  463  for connection to jack contacts and with PCB-compliant pins  464  for connection to a printed circuit board. A side view of the flexible shunt  466  is shown in  FIG. 60 .  FIG. 61  is a side view illustrating the placement of a flexible shunt  466  between jack contacts  468  and a printed circuit board  470 . A segment of a plug  471  is shown, and the plug/jack contact interface  473  is directly above the location of attachment of the rivets  462  to the jack contacts  468 .  FIG. 62  is a cross-sectional view of the flexible shunt  466  along the line Q-Q of  FIG. 59 . A conductive trace  472 , such as a copper trace, is surrounded by a dielectric  474  such as KAPTON® polyimide film manufactured by DuPont. The use of a flexible circuit shunt  466  shortens the current path from the plug  471  to the PCB  470 .  FIGS. 59-62  show a flexible shunt  466  providing electrical connection only, with no capacitor plates. The use of a flexible circuit shortens the current path from the plug  471  to the printed circuit board  470 . For example, the signal length x 2  shown in  FIG. 61  is less than the signal length x 1 . 
         [0215]      FIGS. 63-72  show an alternative flexible circuit capacitor  476  for implementing a NEXT compensation zone.  FIG. 63  is a perspective view of two flexible circuit capacitors  476   a  and  476   b  having domed rivets  478  for attachment to first through eighth jack contacts as labeled in  FIG. 63 .  FIG. 64  is a detail view of the detail “R” of  FIG. 63  showing a domed rivet  478  adapted for welded attachment to a jack contact and a plated through hole  480  for establishing electrical connection between a jack contact and capacitive plates  482 , shown as dotted lines in  FIG. 63 .  FIG. 65  is a top view of the flexible circuit capacitor  476  more clearly showing the arrangement of the capacitive plates  482  and  FIG. 65  is a side view of the flexible circuit capacitor  476 , showing a 90° bend  475 . 
         [0216]      FIG. 67  is a perspective view showing a flexible circuit capacitor  476   a  attached to four jack contacts  484 .  FIG. 68  is another perspective view, showing an additional flexible circuit capacitor  476   b  attached to the other four jack contacts  484 . The two flexible circuit capacitors  476   a  and  476   b  partially overlap each other.  FIGS. 69 and 70  are respectively side and rear views showing the flexible circuit capacitors  476   a  and  476   b  attached to the jack contacts  484 . A first flexible circuit capacitor  476   a  is attached to first, second, third, and fifth jack contacts  484 , and a second flexible circuit capacitor  476   b  is attached to fourth, sixth, seventh, and eighth jack contacts  484  as shown in  FIGS. 68 and 70 . 
         [0217]    The overlap of capacitive plates within a flexible circuit capacitor  476  is shown in  FIGS. 71 and 72 .  FIGS. 71 and 72  show the flexible circuit capacitor for connection to first, second, third, and fifth jack contacts; the capacitors connected to eighth, seventh, sixth, and fourth contacts are a minor image of the illustrated capacitors. All pair combinations except for 1,2-7,8 are included. The flexible circuit capacitors  476   a  and  476   b  are welded to the bottom of jack contacts directly below the plug/jack contact interface. 
         [0218]    Turning now to  FIGS. 73-88 , a flexible printed circuit  486  with a capacitive and inductive NEXT compensation zone is shown.  FIG. 73  is a perspective view of a flexible printed circuit  486  with rivets  488  for connection to jack contacts and printed-circuit-board compliant pins  464  for connection to a printed circuit board. The flexible printed circuit  486  can flex between jack contacts and a printed circuit board when a plug is mated to jack contacts, and the rivets  488  are welded directly beneath a plug/jack contact interface.  FIG. 74  is a plan view of a flexible printed circuit  486  showing conductive pathways  490  with dotted lines. A flexible printed circuit  486  for providing a NEXT compensation zone for conductors 1, 2, 3, and 5 is shown; a flexible printed circuit for providing a NEXT compensation zone for conductors 4, 6, 7, and 8 is a mirror image of the shown flexible printed circuit  486 . Conductive pathways  490  are provided within the flexible printed circuit  486  such that the flexible printed circuit  486  provides both capacitive and inductive NEXT compensation on all conductor pairs except 1,2-7,8. 
         [0219]      FIG. 75  is a cross-sectional view along the line S-S of  FIG. 74  and  FIG. 76  is a cross-sectional view along the line T-T of  FIG. 74 . These views show the positioning of conductive pathways  490  along first and second cross-sections of the flexible printed circuit  486 . 
         [0220]      FIGS. 77-80  are plan views respectively showing in solid lines the conductive pathways  490   a - 490   d  associated with first, second, third, and fifth conductors of an eight-conductor jack. 
         [0221]      FIGS. 81-84  progressively show conductive pathways  490  of the flexible printed circuit  486  as printed on the flexible printed circuit  486  from the lowermost to the uppermost conductive pathway.  FIG. 81  shows the lowermost conductive pathway  490   b  associated with the second conductor.  FIG. 82  shows the second lowermost conductive pathway  490   d  associated with the fifth conductor.  FIG. 83  shows the second uppermost conductive pathway  490   c  associated with the third conductor.  FIG. 84  shows the uppermost conductive pathway  490   a  associated with the first conductor.  FIG. 85  shows a dielectric layer  474  such as a layer of Kapton polyimide film manufactured by DuPont. The flexible circuit  486  is formed by overlapping these layers. 
         [0222]      FIG. 86  is another plan view of the conductive pathways  490   a - 490   d , and  FIGS. 87 and 88  are respectively cutaway views along the lines U-U and V-V of  FIG. 86  showing the overlapping of the conductive pathways  490   a - d . Capacitive plates for the first conductor adjacent capacitive plates for the third conductor and capacitive plates for the second conductor adjacent capacitive plates for the fifth conductor may be added as required. 
         [0223]    Flexible circuit boards according to some embodiments of the present invention may be attached to jack contacts using more than one method of attachment.  FIG. 89  is a perspective view of a flexible circuit capacitor  492  adapted for both welding and adhesive attachment to jack contacts. A rivet  488  is provided for attachment to one jack contact and an adhesive area  446  is provided for attachment to another jack contact.  FIG. 90  is a top view of the flexible circuit capacitor  492 , and  FIGS. 91-93  are, respectively, cross-sectional views of the flexible circuit capacitor  492  taken along the lines W-W, X-X, and Y-Y of  FIG. 90 . A flexible dielectric material  494  overlays first and second conductive plates  440  and  442 . The adhesive area  446  is shown in  FIG. 91  and a rivet  488  extends through a plated through hole  489  as shown in  FIG. 93 .  FIG. 94  is a side view showing the rivet  488  welded to a jack contact  408  and  FIG. 95  is a side view of the adhesive area  446  bonded to a jack contact  408 . As described above, capacitive coupling between the jack contact  408  and the flexible circuit capacitor  492  occurs at the adhesive bond area. Both the weld and the adhesive bond are placed directly beneath a plug/jack contact interface. 
         [0224]    Turning now to  FIGS. 96-104 , a NEXT compensation capacitor circuit  496  for connection to all eight conductors of an eight-conductor jack is illustrated. The NEXT compensation capacitor circuit  496  is a flexible capacitor circuit.  FIG. 96  is a perspective view of a NEXT compensation capacitor circuit  496 . Rivets  497  are provided for welding to the bottoms of jack contacts at plug/jack contact interfaces.  FIG. 97  is a plan view of conductive plates  498  associated with each of the eight contacts of a jack. The association between conductive plates  498   a - 498   h  with the respective first through eighth contacts is shown in  FIG. 98 , which is a side view along the view line Z of  FIG. 97  showing the overlap of the conductive plates  498   a - 498   h.    
         [0225]      FIGS. 99-104  are plan views of the interior of the NEXT compensation capacitor circuit  496  showing the shapes of conductive plates  498   a - 498   h .  FIGS. 99-104  progress from  FIG. 99  which shows the lowermost conductive plate  498   a  of  FIG. 98  (associated with a first jack contact) to  FIG. 104  which shows the uppermost conductive plate  498   h  of  FIG. 98  (associated with an eighth jack contact). 
         [0226]      FIGS. 105-109  illustrate another flexible printed circuit  500  with capacitive and inductive NEXT compensation for attachment to contacts of a jack.  FIG. 105  is a plan view of the flexible printed circuit  500  with dotted lines showing conductive pathways  502 . A first end  504  of the flexible printed circuit  500  is attached to jack contacts via weld/solder pads  505  provided on flexible members  507  and a second end  506  is attached to a printed circuit board via PCB-compliant pins  464 . The flexible printed circuit  500  is adapted for use with third and fifth contacts of an eight-contact jack; an identical flexible printed circuit  500  can also be used with fourth and sixth contacts. 
         [0227]      FIGS. 107-109  show successive layers of the flexible printed circuit  500 .  FIG. 107  shows a first dielectric layer  508   a  and a first conductive pathway  502   a  associated with a third jack contact.  FIG. 108  shows a second dielectric layer  508   b  and a second conductive pathway  502   b  associated with a fifth jack contact.  FIG. 109  shows a third dielectric layer  508   c . The dielectric layers  508   a - c  may be comprised of KAPTON®. 
         [0228]      FIGS. 110 and 111  show flexible printed circuits  500  installed within a jack. Jack contacts  408  are mounted within a sled  426  and the flexible printed circuits  500  are welded to the jack contacts  408  beneath a plug/jack contact interface. The flexible printed circuits  500  are soldered to a PCB  509 .  FIG. 110  shows the jack contacts  408  in a position in which they are not mated to a plug and  FIG. 111  shows the jack contacts  408  in a position in which they are mated to a plug. The flexible printed circuits  500  flex as the jack contacts  408  move between the two positions. The arrows of  FIG. 111  show a current path through the jack including the paths through the flexible printed circuits  500 . 
         [0229]      FIG. 112  is a plan view of another flexible printed circuit  510  for providing capacitive and inductive NEXT compensation. Rivets  511  are provided for attachment to jack contacts. The flexible printed circuit  510  of  FIG. 112  is adapted for attachment to third and fifth jack contacts, but a substantially identical flexible printed circuit can be used for attachment to fourth and sixth jack contacts of an eight-contact jack. Conductive pathways  512   a  and  512   b  are provided within the flexible printed circuit  510 , and capacitor plates  514   a  and  514   b  are attached to each of the conductive pathways  512   a  and  512   b . The vertical runs of the conductive pathways  512   a  and  512   b  are parallel but not collinear. Inductive segments  516   a  and  516   b  make up a portion of the vertical runs. The inductive segments  516   a  and  516   b  are adjacent current carrying conductors and/or transformers providing inductive compensation coupling. 
         [0230]      FIG. 113  is an upper right-side perspective view,  FIG. 114  is a side view, and  FIG. 115  is a front elevational view of one embodiment of a flexible PCB  518  that may be utilized in accordance with the present invention to provide crosstalk compensation. The PCB  518  includes a main portion  520  and attachment fingers, such as the finger  522 . The main portion  520  supports a plurality of capacitive plates (in this case, four plates, corresponding to plug interface contacts 3-6) to provide capacitive coupling. As will be illustrated in  FIGS. 116-121 , the leads to the capacitive plates provide an inductive coupling component as well. The fingers  522  serve as an attachment mechanism for attaching the PCB  518  to the plug interface contacts. While any suitable attachment technique may be used, in the illustrated embodiment, a resistance weld rivet  524  is used. In addition to attaching the PCB  518  to the plug interface contacts (or another conductor connected to the plug interface contacts), the rivet  524  acts as a contact post for the capacitive plates and their leads. This is illustrated in  FIGS. 114-121 , which show four layers of capacitive plates  526  and leads ( 528   a - d ), through which the rivet  524  protrudes to make appropriate contact in the fingers  522 . 
         [0231]      FIG. 116  is a front elevational view of the PCB  518  with the fingers in an unbent configuration, for ease of illustration.  FIG. 117  is a cross-sectional view of the capacitive plates and leads as viewed upward from the bottom of the PCB  518  toward line A/A in  FIG. 116 . Note that  FIG. 114  does not show portions of the PCB  518  that merely support the capacitive plates and leads or serve as a dielectric or insulator.  FIGS. 116-121  show how the capacitive plates and leads are placed with respect to one another to result in a relatively high density of inductive coupling in a relatively short distance. For example, in  FIG. 116 , the capacitive plate  526   a  and lead  528   a  for conductor  5  is the topmost plate and lead shown, having a sideways “U” shape. The same “U” shape, but with varying orientation, is used for conductors  3 ,  4 , and  6 , as shown by the dashed and solid lines of  FIG. 116 . The physical placement and overlapping area of the capacitive plates determines the amount of capacitive coupling. Similarly, the separation of the leads from one another and the length of overlap determine the amount of inductive coupling.  FIG. 117  also illustrates the relative direction of current flow due to inductive couplings in the respective leads, which provides a high density of inductive coupling.  FIGS. 118-121  show, respectively, leads  528   a - d  and capacitive plates  526   a - d  associated with, respectively, fifth, third, sixth, and fourth conductors of an eight-conductor jack. 
         [0232]    While the particular preferred embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the teachings of our invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.