Patent Publication Number: US-7914345-B2

Title: Electrical connector with improved compensation

Description:
BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to electrical connectors, and more particularly, to electrical connectors that utilize differential pairs and experience offending crosstalk and/or return loss. 
     The electrical connectors that are commonly used in telecommunication system, such as modular jacks and modular plugs, may provide interfaces between successive runs of cable in such systems and between cables and electronic devices. The electrical connectors may include contacts that are arranged according to known industry standards, such as Electronics Industries Alliance/Telecommunications Industry Association (“EIA/TIA”)-568. However, the performance to the electrical connectors may be negatively affected by, for example, near-end crosstalk (NEXT) loss and/or return loss. Accordingly, in order to improve the performance of the connectors, techniques are used to provided compensation for the NEXT loss and/or to improve the return loss. Such known techniques have focused on arranging the contacts with respect to each other within the electrical connector and/or introducing components to provided the compensation e.g., compensating NEXT. For example, the compensating signals may be created by crossing the conductors such that a coupling polarity between the two conductors is reversed or the compensating signals may be created by using discrete components. 
     One known technique is described in U.S. Pat. No. 5,997,358 (“the &#39;358 Patent”). The patent discloses a connector that introduces predetermined amounts of compensation between two pairs of conductors that extend from its input terminals to its output terminals along interconnection paths. Electrical signals on one pair of conductors are coupled onto the other pair of conductors in two or more compensation stages that are time delayed with respect to each other. However, the connector in the &#39;358 Patent uses a single interconnection path which may afford only a limited effect on the electrical performance. 
     Thus, there is a need for alternative techniques to improve the electrical performance of the electrical connector by reducing crosstalk and/or by improving return loss. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In one embodiment, an electrical connector that is configured to engage a mating connector having mating contacts and transmit a signal therebetween is provided. The electrical connector includes a housing having a mating end and a loading end. The electrical connector, also includes an array of conductors that have at least one differential pair of conductors that extends between the mating end and the loading end of the housing. The conductors are configured to engage a selected mating contact of the mating connector at the mating interface, and each conductor transmits a signal current. The electrical connector also includes a plurality of traces that extend between the mating and loading ends. Each trace is electrically connected to a corresponding conductor proximate to at least one of the mating end and the loading end. Also, the electrical connector includes a first interconnection path formed by the conductors that extends from the mating interface to the loading end and a second interconnection path formed by the traces that extends from the mating interface to the loading end. The signal current transmitting through at least one conductor of the at least one differential pair is split between the first and second interconnection paths. Also, at least one of the first and second interconnection paths is configured to provide compensation. 
     Optionally, the signal current may be split asymmetrically between the first interconnection path and the second interconnection path. The conductors may be configured to provide only one NEXT compensation stage along the first interconnection path. Also, the traces may be configured to provide a plurality of NEXT compensation stages along the second interconnection path where the NEXT compensation stages do not reverse in polarity. 
     In another embodiment, an electrical connector that is configured to engage a mating connector having mating contacts and transmit a signal therebetween is provided. The electrical connector includes a housing that has a mating end and a loading end. The electrical connector also includes an array of conductors forming at least one differential pair of conductors that extends between the mating end and the loading end within the housing. The conductors are configured to engage a selected mating contact at a mating interface and transmit a signal current. The electrical connector also includes a circuit board assembly having a circuit board disposed within the housing between the mating end and the loading end. The board assembly includes a plurality of traces that extend along the circuit board, where at least one trace is electrically connected to a corresponding conductor proximate to the mating end. The board assembly also includes a connecting member that extends from the circuit board. The connecting member electrically connects the trace to the corresponding conductor proximate to the loading end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an electrical connector formed in accordance with one embodiment of the present invention. 
         FIG. 2  is an exploded view of a contact sub-assembly that may be used with the electrical connector shown in  FIG. 1 . 
         FIG. 3  is an enlarged perspective view of a mating assembly that may be used with the contact subassembly shown in  FIG. 2 . 
         FIG. 4  is a perspective cross-sectional view of the electrical connector shown in  FIG. 1 . 
         FIG. 5  is a schematic side view of a portion of the electrical connector shown in  FIG. 1  when the electrical connector engages a modular plug. 
         FIG. 6A  schematically illustrates one prior known technique that includes multiple stages for providing compensation along one interconnection path. 
         FIG. 6B  illustrates polarity and magnitude for the stages shown in  FIG. 6A  as a function of transmission time delay. 
         FIG. 6C  illustrates a polarity and magnitude vector diagram of the technique shown in  FIGS. 6A and 6B  in complex polar notation. 
         FIG. 7  is a top-perspective view of a circuit board assembly used with the electrical connector shown in  FIG. 1 . 
         FIG. 8  is a bottom-perspective view of the circuit board assembly shown in  FIG. 7 . 
         FIG. 9A  illustrates an electrical schematic of a preferred embodiment of the present invention showing the associated with each stage. 
         FIG. 9B  illustrates a schematic of a more general configuration of the present invention. 
         FIG. 9C  illustrates polarity and magnitude as a function of transmission time delay for the embodiment shown in  FIG. 9A . 
         FIG. 9D  illustrates a polarity and magnitude vector diagram of the embodiment shown in  FIGS. 9A and 9C . 
         FIG. 10  is an exploded perspective view of a circuit board assembly including a plurality of rigid conductors in accordance with another embodiment. 
         FIG. 11  is an exploded view of a contact sub-assembly formed in accordance with another embodiment. 
         FIG. 12  is a schematic side view of a portion of an electrical connector formed in accordance with another embodiment while engaged with a modular plug. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a perspective view of an electrical connector  100  formed in accordance with one embodiment. As shown, the electrical connector  100  is a modular jack, such as an RJ-45 jack assembly, that is configured to engage a mating connector or modular plug  145  (shown in  FIG. 5 ), and transmit data and/ 0 r power therebetween. The electrical connector  100  includes a housing  102  having mating and loading ends  104  and  106 , respectively, and a cavity  108  extending therebetween. When the electrical connector  100  is fully assembled, the cavity  108  is configured to receive the modular plug  145  trough the mating end  104 . However, while the electrical connector  100  is shown and described with reference to an RJ-45jack assembly and a modular plug, the subject matter herein may be used with other types of connectors. 
     The electrical connector  100  includes a plurality of conductors  118  that are configured to interface with mating contacts  146  (shown in  FIG. 5 ) of the modular plug  145 . As will be discussed in greater detail below, in the exemplary embodiment, the electrical connector  100  is configured to split the electrical current of one or more differential signals, hereinafter referred to as “signal current,” transmitting through the mating contacts  146  at a mating interface  120  (shown in  FIG. 3 ). The signal current is split into multiple interconnection paths that are formed by conductors and/or traces. Along each interconnection path, one or more compensation mechanisms, techniques, or components may be used for reducing the negative effects of crosstalk and/or return loss. For example, in the illustrated embodiment, the electrical connector  100  uses adjacent conductors/traces that are electromagnetically coupled to each other via non-ohmic plates to improve the electrical performance of the electrical connector  100 . In addition, the electrical connector  100  may reposition two conductors/traces by crossing paths of the conductors/traces in order to reverse the coupling polarity of the two. However, utilizing non-ohmic plates, open-ended traces, and crossover techniques are only examples of providing compensation in electrical connectors and they are not intended to be limiting. Those skilled in the art understand that various mechanisms, techniques, and components may be used to provide compensation and/or improve return loss. 
       FIG. 2  is an exploded view of a contact sub-assembly  110  that is received within the housing  102  ( FIG. 1 ) through the loading end  106  ( FIG. 1 ) when the electrical connector  100  ( FIG. 1 ) is fully assembled. The contact sub-assembly  110  may include a mating assembly  114 , a wire-terminating assembly  116 , a circuit board assembly  132 , and a circuit board  124 . The board assembly  132  and the circuit board  124  are both configured to be electrically connected to the plurality, of conductors  118  disposed on the mating assembly  114 . In the illustrated embodiment, the board assembly  132  includes a plurality of contact pads  134  on a surface of a circuit board  152  that are electrically connected to a connecting member  136  via a plurality of traces (discussed below). The wire-terminating assembly  116  includes a plurality of insulation displacement contacts (IDCs)  125  that extend therethrough and are configured to engage the circuit board  124 . The IDCs  125  are configured to receive and connect with wires (not shown). 
     The circuit board  152  of the board assembly  132  is configured to be inserted into a cavity (not shown) of the mating assembly  114 . The contact pads  134  may engage corresponding conductors  118  near the mating end  104  ( FIG. 1 ) of the electrical connector  100 . When the electrical connector  100  is fully assembled, the contact sub-assembly  110  is held within the housing  102 . The contact sub-assembly  110  may be secured to the housing  102  by using tabs  112  that project away from sides of the contact sub-assembly  110  and are inserted into and engage corresponding windows  13  (shown in  FIG. 1 ) within the housing  102 . 
       FIG. 3  is an enlarged perspective view of the mating assembly  114 . As shown, the mating assembly  114  may include an array  117  of the conductors  118  that are attached to or supported by a body  119 . The configuration of the array  117  of conductors  118  may be controlled by industry standards, such as EIA/TIA-568. As shown, the array  117  includes eight conductors  118  that are arranged as a plurality of differential pairs P 1 -P 4 . Each differential pair P 1 -P 4  consists of two associated conductors  118  in which one conductor  118  transmits a signal current and the other conductor  118  transmits a signal current that is 180° out of phase with the associated conductor. In the exemplary embodiment, the array  117  of conductors  118  may have an EIA/TIA-568 A modular jack wiring configuration for a typical RJ45 connector. More specifically, the differential pair P 1  includes conductors +4 and −5; the differential pair P 2  includes conductors +6 and −3; the differential pair P 3  includes conductors +2, and −1; and the differential pair P 4  includes conductors +8 and −7. As used herein, the (+) and (−) represent polarity of the conductors. Accordingly, a conductor labeled (+) is opposite, in polarity to a conductor labeled (−) and, as such, the conductor labeled (−) carries a signal that is 180° out of phase with the conductor labeled (+). 
     As shown in  FIG. 3 , the conductor +6 and the conductor −3 of the differential pair P 2  are separated by the conductors +4 and −5 that form the differential pair P 1 . As such, near-end crosstalk (NEXT) may develop between the differential pairs P 1  and P 2 . 
     In alternative embodiments, the array  117  of conductors  118  may have other wiring configurations. For example, the array  117  may be configured under the EIA/TIA-568B modular jack wiring configuration. As such the illustrated configuration of the array  117  is not intended to be limiting. 
     Also shown, the body  119  may include a plurality of slot openings  128 . Each of the conductors  118  includes a mating interface  120  and is configured to extend into a corresponding slot opening  128  such that portions of the conductors  118  are received in corresponding slot openings  128 . The body  119  may form gaps or holes (not shown) that allow the conductors  118  to be electrically connected to the contact pads  134  ( FIG. 2 ). The conductors  118  may be movable within the slot openings  128  to allow flexing of the conductors  118  as the electrical connector  100  ( FIG. 1 ) is mated with the modular plug  145  ( FIG. 5 ). Furthermore, each of the conductors  118  may extend substantially parallel to one another and the mating interfaces  120  of each conductor  118  may be generally aligned with one another. 
     When the electrical connector  100  is assembled, the mating interfaces  120  are arranged within the cavity  108  ( FIG. 1 ) to engage the corresponding mating contacts  146  ( FIG. 5 ) of the modular plug  145 . When the conductors  118  are engaged with the corresponding mating contacts  146  of the modular plug  145 , the conductors  118  may bend or flex into the contact pads  134  of the board assembly  132  ( FIG. 2 ) to make an: electrical connection and form an electrical path. Alternatively, the conductors  118  may be configured to engage or connect with the contact pads  134  even when the modular plug  145  is not engaged with the electrical connector  100 . 
       FIG. 4  is a cross-sectional view of the fully assembled electrical connector  100 , and  FIG. 5  is a schematic side view of a portion of the electrical connector  100  when engaged with the modular plug  145  and shows a portion of the contact sub-assembly  110 . When assembled, the circuit board  152  of the board assembly  132  is positioned within the housing  102  ( FIG. 4 ) such that the conductors  118  engage the contact pads  134  ( FIG. 5 ). The circuit board  124  may be oriented vertically within the housing  102  such that the circuit board  124  is substantially perpendicular to, and spaced apart a predetermined distance from, the circuit board  152  of the board assembly  132 . The circuit board  124  may facilitate connecting the conductors  118  to the IDCs  125 . Furthermore, the board assembly  132  may be positioned generally forward of the circuit board  124 , in the direction of the mating end  104  ( FIG. 4 ). However, the positions of the circuit board  124  and the circuit board  152  are only exemplary, and the circuit board  124  and the circuit board  152  may be positioned, anywhere within the hosing  102  in alternative embodiments. 
     Also shown, a connecting member  136  extends from the board assembly  132  and curves upward to engage the conductors  118  at corresponding nodes  140 . In the exemplary embodiment, an end of the connecting member  136  is embedded within the circuit board  152  of the board assembly  132  and extends therefrom. However, in alternative embodiments, the connecting member  136  may be coupled to one of the surfaces of the board assembly  132  using, for example, an adhesive. As will be discussed in greater detail below, the connecting member  136  facilitates electrically connecting traces within the board assembly  132  to corresponding conductors  118  at the nodes  140 . 
     With reference to  FIG. 5 , when the mating contacts  146  engage the conductors  118  at the corresponding mating interfaces  120 , offending signals that cause noise/crosstalk may be generated. The offending crosstalk (also called NEXT loss) is created by adjacent or nearby conductors through capacitative and inductive coupling which yields the exchange of electromagnetic energy between conductors. In the illustrated embodiment, signal current transmitted between the mating end  104  ( FIG. 1 ) and the loading end  106  ( FIG. 1 ) is split so that a first current portion is transmitted through a first interconnection path X 1  and a second current portion is transmitted through a second interconnection path X 2 . An “interconnection path,” as used herein, is formed by conductors and/or traces of a differential pair that are configured to transmit a signal current between input and output terminals when the electrical connector is in operation. In the illustrated embodiment, the signal current flowing through the differential pair P 2  is split between the interconnection paths X 1  and X 2  and the signal current flowing through the differential pair P 1  only flows along the interconnection path X 1 . However, in alternative embodiments, more than one differential pair can be split into multiple interconnection paths. Furthermore, although the arrows shown in  FIG. 5  for interconnection paths X 1  and X 2  are in one direction, those skilled in the art understand that a communication jack is bi-directional. 
     Optionally, techniques for providing compensation may be used along any interconnection path, such as reversing the polarity of the conductors/traces. Also, non-ohmic plates and discrete components, such as, resistors, capacitors, and/or inductors may be used along the interconnection path for providing compensation. 
     Also shown, the interconnection path X 2  may later split into a plurality of interconnection paths, such as interconnection paths X 2   A  and X 2   B , which are secondary to the interconnection path X 2 . However, embodiments described herein are not intended to be limiting. For example, each interconnection path may be split into secondary interconnection paths and one or more of the secondary interconnection paths may be split into tertiary interconnection paths, etc. Also, an interconnection path may not only be split into two interconnection paths, such as with interconnection paths X 2   A  and X 2   B , but may be split into three or more interconnection paths. 
     By way of example, each differential pair P 1 , P 2 , P 3 , and P 4 . ( FIG. 3 ) transmits signal current along the first interconnection path X 1  from the corresponding mating interface  120  to a corresponding node  140  and to the output terminals through IDC&#39;s  125 . Additionally, in the exemplary embodiment, the conductors +6 and −3 of differential pair P 2  and conductors +4 and −5 of differential pair P 1  are each electrically connected to corresponding traces (discussed below) of the board assembly  132  through corresponding contact pads  134 . The traces that are electrically connected to the conductors +6 and −3 extend from the corresponding contact pads  134  through the board assembly  132  and through corresponding connecting members  136  to electrically connect to corresponding nodes  140  and to the output terminals through IDC&#39;s  125 . Thus in one embodiment, the electrical connector  100  includes the interconnection path X 1  that extends from the mating interfaces  120  through the array  117  of conductors  118  to nodes  140  and to the output and the interconnection path X 2  that extends from the mating interfaces  120  through the traces of the board assembly  132  to the nodes  140  and to the output terminals through IDC&#39;s  125 . 
     As shown in the exemplary embodiment, each interconnection path X 1  and X 2  may include one or more NEXT stages. A “NEXT stage,” as used herein, is a region where signal coupling (i.e., crosstalk) exists between conductors or pairs of conductors and where the magnitude and phase of the crosstalk are substantially similar, without abrupt change. An interconnection path may have multiple NEXT stages within it. Also, the NEXT stage could be a NEXT loss stage, where offending signals are further generated, or a NEXT compensation stage, where NEXT compensation is provided. For purposes of analysis, the average crosstalk along each NEXT stage may be represented by a vector whose phase is measured at the midpoint of the NEXT stage. This does not apply to the initial offending crosstalk generated at the mating interface node  120  ( FIG. 5 ), which is represented by a vector whose phase is zero. In one embodiment, NEXT compensation for the NEXT loss generated at the mating interface  120  ( FIG. 3 ) is only provided by the board assembly  132  and the conductors  118  (i.e., not within the circuit, board  124 ). However, those skilled in the art understand that NEXT compensation may be generated with the circuit board  124  if desired. 
     Furthermore, in one embodiment, the interconnection path X 2  has a higher impedance than the interconnection path X 1  such that a larger portion of the signal current travels through the interconnection path X 1 . Accordingly, embodiments described herein may sustain larger amounts of power without overheating than previously known electrical connectors. 
       FIGS. 6A-6C  illustrate one known technique that is described in the &#39;358 Patent for creating compensation crosstalk in an electrical connector. As shown in  FIG. 6A , conductors  501 - 504  extend between input terminals  51  and output terminals  52  of connecting apparatus  500 . The conductors  501  and  504  form one wire pair that straddles another wire pair formed by the conductors  502  and  503 . 
       FIG. 6B  graphically illustrates the crosstalk between the two pairs along a time axis. The vector A 0 , generated in stage 0, represents the offending crosstalk (NEXT loss). As shown in  FIG. 6A , compensation is provided by crossing conductor  502  over the path of conductor  303  so that the polarity of the crosstalk between the conductor pairs is reversed. Accordingly, stage I provides compensating crosstalk, A 1 , i.e., the crosstalk has a polarity opposite to the polarity of the offending crosstalk A 0  in stage 0. As shown in  FIG. 6B , the magnitude of A 1  is approximately twice the magnitude of A 0 . Stage II is another compensation stage that provides further compensating crosstalk, A 2 , that is shown having the same approximate magnitude of crosstalk as the offending crosstalk A 0 , but an opposite polarity with respect to stage I. By selecting the crossover locations and the amount of signal coupling between the conductors  501 - 504 , the magnitude and phase of vectors A 0 , A 1 , and A 2  (illustrated in  FIG. 6C ) can be selected to approximately cancel each other. As shown in  FIGS. 6A-6C  and as known in the prior art, the offending crosstalk and compensating crosstalk for each wire pair are provided on a single interconnecting path. 
     As is understood by the inventors, the signal coupling or crosstalk that occurs along the stages 0, I, and II shown in  FIGS. 6A-6C  may be written in complex polar notation as vectors {right arrow over (A)} o , {right arrow over (A)} 1 , and {right arrow over (A)} 2 . The initial crosstalk is defined by the vector {right arrow over (A)} 0  shown in the following equation:
 
{right arrow over (A)} 0 =|A 0 |e iφis 0 =|A 0 |  (Equation 1)
 
where |A 0 | is the complex magnitude and e iφ     0    is the complex phase shift relative to the offending NEXT in {right arrow over (A)} 0 . The phase shift for {right arrow over (A)} 0  is φ 0 =0. The compensating crosstalk generated in stage I is represented by the complex vector and the compensating crosstalk in stage II is represented by the complex vector {right arrow over (A)} 2 .
 
     In order for stages I and II to cancel out the offending crosstalk or NEXT loss generated by {right arrow over (A)} 0 , the vector sum of {right arrow over (A)} 1  and {right arrow over (A)} 2  should be approximately equal to {right arrow over (A)} 0 . Furthermore, if additional stages are used, all of the vectors that represent offending or compensating crosstalk that occurs along the interconnection path after stage 0 should all be summed to be approximately equal to {right arrow over (A)} 0 . Thus, if φ 2 −2φ 1 , an equation may be made that generally represents an electrical connector using multiple NEXT stages with alternating polarity as shown above: 
                          A   0          ≈     -       ∑     n   =   1     N     ⁢         (     -   1     )     n     ⁢          A   n          ⁢     ⅇ     ⅈϕ   n                     (     Equation   ⁢           ⁢   2     )               
where “N” equals the total number of stages.
 
     As will discussed in greater detail below, the electrical connector  100  ( FIG. 1 ) uses multiple NEXT stages to effectively reduce or cancel the offending crosstalk {right arrow over (A)} 0 . However, the electrical connector  100  splits the signal current between multiple interconnection paths, e.g., X 1  and X 2  which may each have one or more NEXT compensation stages. Furthermore, although the known crossover technique discussed above may be used to provide compensating crosstalk, the electrical connector  100  may use other means of providing compensation. For example, the interconnection paths X 1  and X 2  may include non-ohmic plate and/or discrete components, such as resistors, capacitors, and inductors to facilitate providing compensation. 
       FIGS. 7 and 8  are top and bottom perspective views, respectively, of the board assembly  132  coupled to the connecting member  136 . In the exemplary embodiment, the board assembly  132  is configured to provide one or more stages of compensation for the electrical connector  100  using, for example, traces and non-ohmic plates. As used, herein, the term “non-ohmic plate” refers to a conductive plate that is not directly connected to any conductive material, such as traces or ground. In one embodiment, the non-ohmic plates may be positioned relative to one or more open-ended traces and/or one or more contact traces within the circuit board. As used herein, the term “open-ended traces” refers to traces that do not carry a signal current when the electrical connector  100  is operational. As used herein, the term “contact trace” is a trace that extends between two points and carries a signal current therebetween. When in use, the non-ohmic plate may electromagnetically couple, i.e., magnetically and/or capacitatively couple, to the open-ended and/or contact traces. As such, the non-ohmic plate and corresponding traces may be configured to provide compensation. 
     In alternative embodiments, the open-ended and contact traces may electromagnetically couple and provide compensation without using a non-ohmic plate. For example, the contact traces may extend adjacent to each other and cross-over, similar to that described above in  FIGS. 6A-6C . Also, the distances separating the adjacent traces, whether open-ended or contact traces, may be narrowed or widened in order to affect the electromagnetic coupling. Discrete capacitors defined by piezoelectric fingers may also be used to provide compensation. 
     As shown in  FIGS. 7 and 8 , the board assembly  132  includes the circuit board  152 . The circuit board  152  may be formed from a dielectric material and may be substantially rectangular and have a length L B , a width W B , and a substantially constant thickness T B . Alternatively, the circuit board  152  may be other shapes. The circuit board  152  may be formed from multiple layers. The circuit board  152  may also include a protruded portion  153 . As shown, the circuit board  152  includes a plurality of outer surfaces S 1 -S 6 , including a top surface, S 1 , a bottom surface S 2 , and side surfaces S 3 -S 6 . The top and bottom surfaces S 1  and S 2 , respectively, are on opposite sides of the circuit board  152  and are separated by the thickness T B . Opposing side surfaces S 4  and S 6  are separated by the length L B ; and opposing side surfaces S 3  and S 5  are separated by the width W B . 
     As shown in  FIG. 7 , the surface S 1  may include a plurality of contact pads  211 - 214  and trace pads  215 - 217 . The contact pads  211 - 214  may be aligned with respect to each other and proximate to a mating end  218  of the board assembly  132  such that the contact pads  211 - 214  are proximate to the mating end  104  ( FIG. 1 ) when the connector is fully assembled. The trace pads  215 - 217  may be aligned with respect to each other and proximate to a rear end  219 , which may be proximate to the loading end  106  ( FIG. 1 ). Also shown, the surface S 1  may include a plurality of traces  221 - 224  thereon. Each trace  221 - 224  extends from a corresponding contact pad or trace pad. More specifically, traces  221 ,  222 , and  224  may extend from contact pads  211 ,  212 , and  214 , respectively. The traces  221  and  224  are contact traces and extend lengthwise from the contact pads  211  and  214 , respectively, toward the rear end  219  and couple to a trace pad  215  and  217 , respectively. The trace  222  is open-ended and extends lengthwise from the contact pad  212  toward the rear end  219  and terminates at a position on the surface S 1  and adjacent to the trace  224 . The trace  223  is open-ended and extends lengthwise from the trace pad  216  toward the mating end  218  and terminates at a position on the surface S 1  and adjacent to the trace  221 . 
     With respect to  FIG. 8 , the surface S 2  may include a plurality of trace pads  231 ,  233 , and  234  positioned near the mating end  218  and a plurality of trace pads  235 ,  236 , and  238  positioned near the rear end  219 . Each trace pad  231 ,  233 , and  234  is connected to one of the contact pads  211 ,  213 , and  214  ( FIG. 7 ), respectively, through corresponding vias  251 ,  253 , and  254 , which extend; through the thickness T B  proximate to the mating end  218 . Likewise, each trace pad  235 ,  236 , and  238  is connected to one of the contact pads  217 ,  216 , and  215  ( FIG. 7 ), respectively, through corresponding vias  255 ,  256 , and  257 . Also, the board assembly  132  includes a plurality of traces  241 - 244  on the surface S 2  that extend from corresponding trace pads. More specifically, the traces  241 ,  243 , and  244  extend from the trace pads  231 ,  233 , and  234 , respectively, lengthwise toward the rear end  219 . The trace  242  extends from the rear end  219  lengthwise toward the mating end  218 . The traces  241  and  244  are contact traces and extend completely between corresponding trace pads, whereas the traces  243  and  242  are open-ended traces that terminate at a position along the surface S 2 . The trace  243  is positioned adjacent to the trace  241 , and the trace  242  is positioned adjacent to the trace  244 . 
     As discussed above, the board assembly  132  may also include non-ohmic plates  271 - 274  to facilitate electromagnetic coupling adjacent traces. The non-ohmic plates  271 - 274  may be “free-floating,” i.e., the plates do not contact either of the adjacent traces or any other conductive material that leads to one of the conductors  118  or ground. In one embodiment, the board assembly  132  may have multiple layers where the non-ohmic plates  271 - 274  and the traces are on separate layers. Furthermore, in the illustrated embodiment, the non-ohmic plates  271 - 274  are substantially rectangular; however, other embodiments may have a variety of geometric shapes. In the illustrated embodiment, the non-ohmic plates are embedded within the circuit board  152  a distance from the corresponding traces to provide broadside coupling with the traces. Alternatively, the non-ohmic plates may be co-planer (e.g., on the corresponding surface) with respect to the adjacent traces and positioned therebetween such that each trace electromagnetically couples with an edge of the non-ohmic plate. 
     In the exemplary embodiment, each non-ohmic plate  271 - 274  is positioned near adjacent traces that include one open-ended trace and one contact trace. More specifically, as shown in  FIG. 8 , the non-ohmic plate  271  is positioned within the circuit board  152  near the open-ended trace  243  and the contact trace  241 , and the non-ohmic plate  273  is positioned within the circuit board  152  near the open-ended trace  242  and the contact trace  244 . As shown in  FIG. 7 , the non-ohmic plate  272  is positioned within the circuit board  152  near the open-ended trace  223  and the contact trace  221 , and the non-ohmic plate  274  is positioned within the circuit board  152  near the open-ended trace  222  and the contact trace  224 . Although other sizes and positions may be used, in the illustrated embodiment, the non-ohmic plates  271  and  274  have a substantially equal length and are longer than the non-ohmic plates  272  and  273 , and the non-ohmic plates  271  and  274  are positioned closer to the mating end  218 , whereas the non-ohmic plates  272  and  273  are positioned closer to the rear end  219 . 
     However, alternative embodiments are not limited to using non-ohmic plates to electromagnetically couple one open-ended trace to one contact trace. For instance, a non-ohmic plate may couple a plurality of open-ended traces to one or more contact traces or a non-ohmic plate may couple a plurality of contact traces to one open-ended trace. Also, a non-ohmic plate may be used to couple two or more contact traces or two or more open-ended traces. In addition, alternative embodiments may not use a non-ohmic plate. 
     When the electrical connector  100  is fully assembled and in operation, the conductors  118  ( FIG. 3 ) that form differential pairs P 1  and P 2  ( FIG. 3 ) are coupled to the contact pads  211 - 214  ( FIG. 7 ). As such, the traces  221 - 224  (FIG.  7 ) and  241 - 244  ( FIG. 8 ) are electrically connected to the conductors  118  that form the differential pairs P 1  and P 2 . With respect to the differential pair P 1 , the conductor +4 and the conductor −5 electrically connect to the contact pads  213  and  212 , respectively, and the open-ended traces  243  and  222 , respectively, near the mating end  218 . The conductors +4 and −5 are electrically connected to the open-ended traces  242  and  223 , respectively, through the connecting member  136  at the rear end  219 . More specifically, the conductor +4 is electrically connected to the open-ended trace  242  through a corresponding member trace  190  (discussed below) of the connecting member  136 . The conductor −5 is electrically connected to the open-ended trace  223  through trace pad  216 , via  256 , trace pad  236 , and a corresponding member trace  190  of the connecting member  136 . 
     With respect to the differential pair P 2 , the conductor −3 is electrically connected to the contact pad  214  and the conductor +6 is electrically connected to the contact pad  211 . Accordingly, the signal current carried by the conductor −3 is split such that a first signal current portion is directed through the contact trace  224  and a second signal current portion is directed through the contact trace  244 . The signal current conveyed by the conductor +6 is split such that a first portion of the signal current is directed through the contact trace  221  and a second portion of the signal current is directed through the contact trace  241 . More specifically, the conductor +6 for the differential pair P 2  goes through path X 2   A  along the contact pad  211 , the contact trace  221 , and the trace pad  215  and through path X 2   B  along the trace pad  231 , the contact trace  241 , and the trace pad  238 . The signal from the conductor −3 for the differential pair P 2  goes through path X 2   A  along the contact pad  214 , the contact trace  224 , the trace pad  217 , and through path X 2   B  along the trace pad  234 , the contact trace  244 , and the trace pad  235 . 
     By way of example and with specific reference to adjacent traces  221  and  223  shown in  FIG. 7 , when the board assembly  132  is in use, electromagnetic energy may travel down the trace  221  and radiate the electromagnetic energy in the form of electric and magnetic fields that couple to the non-ohmic plate  272 . The electromagnetic energy may then travel across a surface of the non-ohmic plate  272  and radiate from the plate surface to the trace  223 . Thus, the board assembly  132  may use non-ohmic proximity energy coupling to compensate or reduce crosstalk between the differential pairs P 1  and P 2  and/or improve the return loss at a desired frequency range of interest. However, those having ordinary skill in the art will understand that an insignificant or minimal amount electromagnetic coupling may occur with other traces in the board assembly  132 . As such the type, position, geometric shape, and other factors relating to these traces may be considered when designing the board assembly  132 . 
     Also shown in  FIGS. 7 and 8 , the connecting member  136  extends from or is attached to the rear end  219  of the circuit board  152 . In one embodiment, the connecting member  136  includes a unitary body  188  that may be constructed from a material that is more flexible than the board assembly  132 . The body  188  comprises a plurality of ribs  189  mat extend away from the rear end  219  Each rib  189  may include a member trace  190  that is electrically connected to one of the traces on the board assembly  132  at one end of the member trace  190  and couples or forms into a node pad  191  at the other end of the member trace  190 . The node pad  191  is configured to electrically connect with one of the conductors  118  at the corresponding node  140  ( FIG. 5 ). As such, the traces of the board assembly  132  may be electrically connected to corresponding conductors  118  in the array  117  ( FIG. 3 ). 
       FIGS. 9A-9D  schematically illustrate in detail one technique for providing NEXT compensation in accordance with an exemplary embodiment of the present invention. As shown, the interconnection paths X 1  and X 2 , have an asymmetric relationship with respect to each other. As used herein, two interconnection paths that extend in parallel to each other are “asymmetric” if one interconnection path splits into secondary interconnection paths and the other interconnection path does not, thereby generating effectively different time delays for the interconnection paths relative to each other. For example, the interconnection path X 2  splits into secondary interconnection paths X 2   A  and X 2   B , whereas the interconnection path X 1  does not. Due to the asymmetric relationship, the interconnection paths X 1  and X 2  will have effectively different time delays (discussed further below). 
       FIG. 9A  illustrates a schematic of the electrical configuration for interconnection paths X 1  and X 2 . Stage 0 represents the mating interfaces  120  where the NEXT loss {right arrow over (A)} 0  is generated. The interconnection paths X 1  and X 2  split at the mating interfaces  120  and rejoin each other at the nodes  140 . Alternatively, the interconnection paths X 1  and X 2  may split at some point after the mating interface  120 . As shown, the interconnection path X 1  extends along stages IIIA and IIIB through the conductors  118  of the differential pairs P 1  and P 2  (i.e., the conductors +4 and −5 of the differential pair P 1  and the conductors −3 and +6 of the differential pair P 2 ). While the signal current travels along the conductors  118  in stage IIIA, NEXT loss is generated. Stage IIIA continues until the conductor +4 and the conductor −5 are crossed over each other. The signal current also travels along conductors  118  in stage IIIB where NEXT compensation is generated. Stage V where the NEXT compensation {right arrow over (A)} 1  is generated, spans between node  140  and the IDC  125  ( FIG. 5 ). 
     Although not shown, the differential pairs P 3  and P 4  also extend along the interconnection path X 1  and include one NEXT loss stage and one NEXT compensation stage. However, in alternative embodiments, the interconnection path X 1  may include more than one NEXT compensation stage and/or NEXT loss stage. 
     As shown in  FIG. 9A , the interconnection path X 2  travels along stages I, IIA, IIB, and IV. Initially, the interconnection path X 2  extends from the mating interfaces  120  along the conductors  118  in a direction opposite that of the interconnection path X 1 . Stage I ends when the interconnection path X 2  is then sub-divided at the contact pads  211  and  214  ( FIG. 7 ) into two secondary interconnection paths X 2   A  and X 2   B . The secondary interconnection paths X 2   A  and X 2   B  extend along the circuit board  152  ( FIG. 2 ) between the contact pads  211  and  214  and the trace pads  235 and  238  ( FIG. 8 ). The interconnection path X 2   A  includes the contact traces  221  and  224 . The interconnection path X 2   B  includes the contact traces  241  and  244  The interconnection paths X 2   A  and X 2   B  are reunited at the trace pads  235  and  238 . Stage IV extends from the trace pads  235 and  238  along the corresponding member traces  190  of the connecting member  136  to the nodes  140  where the interconnection paths X 1  and X 2  for the differential pair P 2  are reunited. 
     As shown in  FIG. 9A , the conductors  118  are arranged in order as +6, −5, +4, and −3 at the mating interfaces  120 . When the interconnection paths X 1  and X 2  are reunited at the nodes  140 , the order of the conductors  118  is changed to +6, +4, −5, and −3. In the illustrated embodiment, the polarity between the conductors of the differential pair P 1  is reversed only once. Other embodiments, however, may alternate the polarity multiple times. 
       FIG. 9A  also illustrates the complex vectors associated with each NEXT stage. More specifically, the complex vector {right arrow over (A)} 0  represents the NEXT loss generated at stage 0, which may form the main source of NEXT loss. The complex vector {right arrow over (B)} 0  represents the NEXT loss generated by conductors  118  of the interconnection path X 1  along stage IIIA. The complex vector {right arrow over (B)} 1  represents the NEXT compensation generated by the conductors  118  extending along stage IIIB. With reference to the interconnection path X 2 , the complex vector {right arrow over (E)} (Equation 3) represents the NEXT loss generated by the conductors  118  that extend along stage I. The interconnection path X 2  is then split further into secondary paths X 2   A  and X 2   B . The complex vector {right arrow over (C)} 0  represents the NEXT loss generated along the secondary path X 2   A  and the complex vector {right arrow over (D)} 0  represents the NEXT loss generated along the secondary path X 2   B . At the point between stages IIA and IIB, the polarity of the NEXT signals is effectively reversed such that NEXT compensation is now generated along the secondary path X 2   A  and the secondary path X 2   B , which is represented by the complex vectors {right arrow over (C)} 1  and {right arrow over (D)} 1 , respectively. When the traces along the secondary path X 2   A  and secondary path X 2   B  are reunited, the member traces  190  continue to generate NEXT compensation along stage IV, which is represented by the complex vector {right arrow over (F)} (Equation 4). Lastly, the complex vector {right arrow over (A)} 1 , defines the NEXT compensation at stage V that is generated by the physical region that spans between node  140  and the IDC  125  ( FIG. 5 ).
 
{right arrow over (E)}=|E|e iα   (Equation 3)
 
{right arrow over (F)}|F|e iβ   (Equation 4)
 
       FIG. 9B  illustrates a general schematic of an electrical configuration for some embodiments of the present invention. For example, the interconnection path X 1  may include more than two NEXT stages. As such, the NEXT vectors, {right arrow over (B)} 0 , {right arrow over (B)} 1 , and any additional complex vectors for any additional NEXT stages along the interconnection path X 1  maybe defined in general by the complex vector array {right arrow over (B)} 1 , (Equation 5).
 
 {right arrow over (B)}   1   =[|B   0   |e   iγ     0     , −|B   1   |e   iγ     1     , |B   2   |e   iγ2 , . . . , (−1) 1   |B   1   |e   iγ     1   ]  (Equation 5)
 
Similarly the NEXT vectors, {right arrow over (C)} 0 , {right arrow over (C)} 1 , and any additional complex vectors for any additional NEXT stages along the interconnection path X 2   A  may be defined in general by the complex vector array {right arrow over (C)} m (Equation 6), and the vectors NEXT vectors, {right arrow over (D)} 0 , {right arrow over (D)} 1 , and any additional complex vectors for any additional NEXT stages along the interconnection path X 2   B  are defined in general by the complex vector array {right arrow over (D)} n  (Equation 7).
 
 {right arrow over (C)}   m   =[|C   0   |e   iθ     0   , −|C 1   |e   iθ     1   , |C 2   |e   iθ     2   , . . . , (−1) m   |C   m   |e   iθ     m   ]  (Equation 6)
 
{right arrow over (D)} n   =[|D   0   |e   iΨ     0     , −|D   1   |e   iΨ     1   , |D 2   |e   iΨ     2   , . . . , (−1) m   |D   n   |e   iΨ     n   ]  (Equation 7)
 
     As discussed above, the overall purpose of the stages I-V is to cancel or minimize the NEXT loss provided {right arrow over (A)} 0  at stage 0. However, the configuration of the electrical connector  100  is more complicated than discussed above with respect to the cross-over technique in  FIGS. 6A-6C  along one interconnection path. For example, in addition to the NEXT loss vector, {right arrow over (A)} 0 , the electrical connector  100  must also consider the interface between the IDC terminals and the conductors and traces at the node  140 , represented by the vector {right arrow over (A)} 1 . Accordingly, in order to effectively cancel or minimize the NEXT loss, the electrical connector  100  is configured such that the summation of the vectors: {right arrow over (A)} 0 , {right arrow over (A)} 1 , {right arrow over (B)} 1 , {right arrow over (C)} m , {right arrow over (D)} m , {right arrow over (E)}, and {right arrow over (F)} is approximately equal to zero. Thus: 
                   0   ≈            A   0          +          E        ⁢     ⅇ   ⅈα       +       ∑     l   =   0     L     ⁢         (     -   1     )     l     ⁢          B   l          ⁢     ⅇ     ⅈγ   l           +       ∑     m   =   0     M     ⁢         (     -   1     )     m     ⁢          C   m          ⁢     ⅇ     ⅈθ   m           +       ∑     n   =   0     N     ⁢         (     -   1     )     n     ⁢          D   n          ⁢     ⅇ     ⅈΨ   n           -            A   1          ⁢     ⅇ     ⅈϕ   1         -          F        ⁢     ⅇ   ⅈβ                 (     Equation   ⁢           ⁢   8     )               
where L, M, and N are equal to the maximum number of compensation vectors or stages for {right arrow over (B)} 1 , {right arrow over (C)} m  and {right arrow over (D)} n , respectively.
 
       FIG. 9C  shows a NEXT polarity, magnitude, and time diagram of an exemplary embodiment of the electrical connector  100 . The representative magnitude of NEXT stage 0 is |A 0 |; the representative magnitude of stage I is |E|; the representative magnitude of stage IIA includes |C 0 | and |D 9 | the representative magnitude of stage IIB includes |C 1 | and |D 1 |; the representative magnitude of stage IV is |F|; the representative magnitude of stage IIIA is |B 0 |; the representative magnitude of stage IIIB is |B 1 |; and the representative magnitude of stage V is |A 1 |. The NEXT loss stages have a positive polarity and includes stages 0, I, IIA, and IIIA. The NEXT compensation stages have a negative polarity and include stages IIB, IIB, IV, and V. (Additional compensation stages, if used, may have a negative or positive polarity.) Thus, each NEXT stage is shown with a representative magnitude and polarity along the time axis. 
     Also shown, a representative time delay associated with each stage showing that the interconnection path X 1 , τ 1 , will be different than a time delay associated with the interconnection path X 2 , τ 2 , because of the asymmetric divisions of the interconnection paths X 1  and X 2 . For example, τ 1 , is divided into τ 1 4 as a signal flows through X 1 ; whereas τ 2  is divided into τ 2 /6 as a signal flows through stages 0, I, II, IV, and V in X 2 . As such, signal current flowing through interconnection path X 1  will experience a time delay τ 1 , and signal current flowing through interconnection path X 2 , which further splits into X 2   A  and X 2   B , will experience a different time delay τ 2 . Accordingly, different phase shifts may be experienced along the interconnection paths X 1  and X 2 . 
       FIG. 9D  is a graph illustrating the multiple complex vectors along the interconnection paths X 1  and X 2  on imaginary and real axes. As shown, the complex vectors are configured to approximately cancel each other out to reduce the negative effects of NEXT loss. Furthermore, compared to the graph shown in  FIG. 6C , which illustrates a known compensation method along one interconnection path, the electrical configuration of the electrical connector  100  has more than one interconnecting path, i.e., interconnection paths X 1  and X 2 , which may more effectively improve the electrical performance. In the illustrated embodiment, when the signal current is split between two or more interconnection paths, the offending signals generated by crosstalk near the mating interfaces may be compensated for through one or more NEXT compensation stages along each interconnection path where the polarity along each interconnection path is reversed only once. However, in alternative embodiments, the interconnection path may have multiple compensation stages where the polarity is reversed. Because the offending signals are split, the offending signals may be compensated for in a more efficient manner and the electrical connector can achieve better performance than compared to known connectors. For example, the magnitude of the offending NEXT loss is divided and isolated along each interconnection path thereby reducing the amount of compensation stages needed along each interconnection path to approximately cancel put the offending NEXT loss. 
     Thus, unlike prior art/techniques having multiple stages of compensation along a single interconnection path, the electrical connector  100  may provide multiple interconnection paths that each may provide one or more stages of compensation. When the interconnection paths are asymmetric, additional options and techniques are possible for providing compensation to the connector. Furthermore, because the signal current is split between interconnection paths, the electrical connector  100  may carry more power than other known electrical connectors. 
     In alternative embodiments, the interconnection paths X 1  and X 2  may be symmetric (i.e., the interconnection paths X 1  and X 2  may both have a common time delay associated with the electrical signal relative to {right arrow over (A)} 0 ). For example, the interconnection paths X 1  and X 2  may each have only one crossover that occur at the same location where there is a common time delay associated with the electrical signal relative to {right arrow over (A)} 0 . 
       FIG. 10  is a perspective view of an alternative circuit board assembly  331  that may be used with an electrical connector (not shown) formed in accordance with an alternative embodiment. The circuit board assembly  331  includes a circuit board  332  and may also include contact pads, traces, non-ohmic plates, and other features, such as those discussed above with respect to the circuit board assembly  132  ( FIG. 7 ). Also shown, a plurality of connecting members  390  may be attached to a rear end  319  of the circuit board  332 . The connecting members  390  are substantially rigid conductors that perform similar functions as the member traces  190  ( FIG. 7 ) used with the connecting member  136  ( FIG. 7 ). Each connecting member  390  has a board end portion  392  and a mating end portion  394 . The board end portion  392  is configured to engage a contact pad (not shown) on a bottom of top surface of the circuit board  332 , and the mating end portion  394  is configured to engage a conductor, such as the conductor  118  shown in  FIG. 3 . 
       FIG. 11  is ah exploded view of an alternative contact sub-assembly  410  that may be used with an electrical connector (not shown) formed in accordance with an alternative embodiment. The contact sub-assembly  410  may include a mating assembly  414  having an array  417  of conductors  418 , a wire-terminating assembly  416 , and circuit boards  424  and  432 . The circuit boards  424  and  432  are both configured to be electrically connected to the plurality of conductors  418  disposed on the mating assembly  414 . The contact sub-assembly  410  may be constructed similarly to the contact sub-assembly  110  ( FIG. 2 ) discussed above. The circuit board  432  may have similar features as described above with respect to the circuit boards  152  and  332 . The circuit board  432  includes a connecting member  436  which functions in a similar manner as in the connecting member  136 . However, the connecting member  436  is configured to electrically couple to some of the IDC&#39;s  425  of the wire-terminating assembly  416 . The conductors  418 , in turn, are configured to engage corresponding pin-holes  440  of the circuit board  424 . In such embodiments, a first interconnection path (not indicated) through the array  417  of conductor  418  may converge with a second interconnection path (not indicated) that travels through the circuit board  432  and joins the first interconnection path within the circuit board  424 . Also, the connecting member  436  may be inserted into the circuit board  432  or, alternatively, the circuit board  432  may be formed around the connecting member  416  during the manufacturing of the circuit board  432 . 
       FIG. 12  is a schematic side view of a portion of yet another contact sub-assembly  510  that may be used with an alternative embodiment of the electrical connector  100 . The contact sub-assembly  510  may have similar features as described with respect to the contact sub-assembly  110  ( FIG. 4 ). The contact sub-assembly  510  includes conductors  518  that engage mating contacts  546  of a modular plug  545  at an interface  520 . The conductors  518  correspond to differential pairs that are electrically connected to traces (not shown)on a circuit board  532  through contact pads  534 . The traces, in turn, are electrically connected to corresponding contact pads  535 . In the illustrated embodiment, each contacts pad  535  and the corresponding conductor  518  electrically connected to one another via a connecting member  536 . Each of the connecting members  536  includes a mating end portion  594  configured to engage one of the conductors  518  and a board end portion  592  configured to engage one of the contact pads  535 . Also, each connecting member  536  is electrically connected to the circuit board  524 . The connecting member  536  has a rigid body that is configured to grip or clamp onto the corresponding conductor  518  and contact pad  535 . 
     As such, the contact sub-assembly  510  may provide multiple interconnection paths Y 1  and Y 2 , where the interconnection paths Y 1  and Y 2  are either asymmetrically or symmetrically divided through the conductors  518  and through the circuit board  532 . The interconnection paths Y 1  and Y 2  may join each other at the connecting members  536 . Also, each interconnection path Y 1  and Y 2  may provide one or more stages of compensation. In one embodiment, the path Y 2  has a higher impedance than the path Y 1  such that a larger portion of the signal current travels through the path Y 1 . 
     As shown above, embodiments described herein may include electrical connectors that utilize multiple interconnection paths. Furthermore, embodiments described herein may include circuit boards and connectors the utilize non-ohmic plates that capacitatively and/or magnetically couple one more open-ended traces to one or more contact traces. The conductors, traces, and the non-ohmic plates may be configured to cause desired effects on the electrical performance. For example, with respect to the traces and non-ohmic plates, the areas of the plate surface and trace surfaces that face each other may be configured for a desired effect. The length of the non-ohmic plate, the widths of the plate and corresponding traces, the distance separating surfaces of the non-ohmic plate and corresponding traces, the distance separating the edges of the traces, and the length of the traces corresponding to the non-coupled portions may all be configured for desired effect. Thus, it is to be understood that the above description is intended to be illustrative, and not restrictive. As such, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. 
     In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Dimensions, types of materials, orientations of the various components, and the number and positions of the various components described herein are intended to define parameters of certain embodiments, and are by on means limiting and are merely exemplary embodiments. Many other embodiments and modifications within the spirit and scope of the claims will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along, with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means—plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phase “means for” followed by a statement of function void of further structure.