Patent Publication Number: US-7708569-B2

Title: Broadside-coupled signal pair configurations for electrical connectors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit under 35 U.S.C. § 119(e) of provisional U.S. Patent Application No. 60/855,558, filed Oct. 30, 2006, and of provisional U.S. Patent Application No. 60/869,292, filed Dec. 8, 2006, the disclosures of which are incorporated herein by reference in their entirety. This application is related by subject matter to U.S. patent application Ser. No. 11/866,061, filed Oct. 2, 2007 and entitled “Broadside-Coupled Signal Pair Configurations For Electrical Connectors,” the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     An electrical connector may provide signal connections between electronic devices using signal contacts. The electrical connector may include a leadframe assembly that has a dielectric leadframe housing and a plurality of electrical contacts extending therethrough. Typically, the electrical contacts within a leadframe assembly are arranged into a linear array that extends along a direction along which the leadframe housing is elongated. The contacts may be arranged edge-to-edge along the direction along which the linear array extends. The electrical contacts in one or more leadframe assemblies may form differential signal pairs. A differential signal pair may consist of two contacts that carry a differential signal. The value, or amplitude, of the differential signal may be the difference between the individual voltages on each contact. The contacts that form the pair may be broadside-coupled (i.e., arranged such that the broadside of one contact faces the broadside of the other contact with which it forms the pair). Broadside or microstrip coupling is often desirable as a mechanism to control (e.g., minimize or eliminate) skew between the contacts that form the differential signal pair. 
     When designing a printed circuit board (PCB), circuit designers typically establish a desired differential impedance for the traces on the PCB that form differential signal pairs. Thus, it is usually desirable to maintain the same desired impedance between the differential signal contacts in the electrical connector, and to maintain a constant differential impedance profile along the lengths of the differential signal contacts from their mating ends to their mounting ends. It may further be desirable to minimize or eliminate insertion loss (i.e., a decrease in signal amplitude resulting from the insertion of the electrical connector into the signal&#39;s path). Insertion loss may be a function of the electrical connector&#39;s operating frequency. That is, insertion loss may be a greater at higher operating frequencies. 
     Therefore, a need exists for a high-speed electrical connector that minimizes insertion loss at higher operating frequencies while maintaining a desired differential impedance between differential signal contacts. 
     SUMMARY 
     The disclosed embodiments include an electrical connector having at least four electrical contacts that form two pairs of differential signal contacts. The first and second electrical contacts may be arranged edge-to-edge along a first direction. The third electrical contact may be adjacent to, and arranged broadside-to-broadside with, the first electrical contact along a second direction substantially transverse to the first direction. The first and third electrical contacts may define one of the pairs of differential signal contacts. The fourth electrical contact may be adjacent to, and arranged broadside-to-broadside with, the second electrical contact along the second direction. The second and fourth electrical contacts may define the other pair of differential signal contacts. The two pairs of differential signal contacts may be offset from one another along the second direction. 
     The electrical connector may include one or more non-air dielectrics, such as a first non-air dielectric disposed between the first and third electrical contacts that form the one pair of differential signal contacts, and a second non-air dielectric disposed between the second and fourth electrical contacts that form the other pair of differential signal contacts. 
     The electrical connector may further include one or more ground contacts. For example, the electrical connector may include a first ground contact adjacent to, and arranged edge-to-edge with, the first electrical contact along the first direction. The electrical connector may also include second ground contact adjacent to, and arranged edge-to-edge with, the third electrical contact along the first direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  depict a portion of a prior-art connector system, in isometric and side views, respectively. 
         FIG. 1C  depicts a contact arrangement of the prior-art connector system shown in  FIGS. 1A and 1B . 
         FIGS. 2A and 2B  depict a portion of a connector system, in isometric and side views, respectively, according to an embodiment. 
         FIG. 2C  depicts an example dielectric material that may be disposed between leadframe assemblies of a plug connector shown in  FIGS. 2A and 2B . 
         FIG. 2D  depicts an example contact arrangement of the plug connector shown in  FIGS. 2A and 2B . 
         FIGS. 3A and 3B  depict a portion of a connector system, in isometric and side views, respectively, according to another embodiment. 
         FIG. 3C  depicts an example contact arrangement of a plug connector shown in  FIGS. 3A and 3B . 
         FIGS. 4A and 4B  depict a portion of a connector system, in isometric and side views, respectively, according to another embodiment. 
         FIG. 4C  depicts an example contact arrangement of a plug connector shown in  FIGS. 4A and 4B . 
         FIGS. 5A and 5B  depict a portion of a connector, in isometric and rear views, respectively, according to another embodiment. 
         FIG. 5C  depicts an example contact arrangement of the connector shown in  FIGS. 5A and 5B . 
         FIG. 6  is a comparison plot of differential insertion loss versus frequency exhibited by the connector shown in  FIGS. 5A-5C . 
         FIG. 7  is a comparison plot of differential impedance versus time exhibited by the connector shown in  FIGS. 5A-5C . 
         FIG. 8  is a table summarizing multi-active, worst-case crosstalk exhibited by the connector shown in  FIGS. 5A-5C . 
         FIGS. 9A and 9B  depict a portion of a connector, in isometric views, according to another embodiment. 
         FIG. 9C  depicts an example contact arrangement of the connector shown in  FIGS. 9A and 9B . 
         FIG. 10  is a comparison plot of differential insertion loss versus frequency exhibited by the connector shown in  FIGS. 9A-9C . 
         FIG. 11  is a comparison plot of differential impedance versus time exhibited by the connector shown in  FIGS. 9A-9C . 
         FIG. 12  is a table summarizing multi-active, worst-case crosstalk exhibited by the connector shown in  FIGS. 9A-9C . 
         FIGS. 13A and 13B  depict a portion of a connector, in isometric views, according to another embodiment. 
         FIG. 13C  depicts a rear view of a portion of the connector shown in  FIGS. 13A and 13B . 
         FIG. 13D  depicts an example contact arrangement of the connector shown in  FIGS. 13A-13C . 
         FIG. 14  is a comparison plot of differential insertion loss versus frequency exhibited by the connector shown in  FIGS. 13A-13D . 
         FIG. 15  is a comparison plot of differential impedance versus time exhibited by the connector shown in  FIGS. 13A-13D . 
         FIG. 16  is a table summarizing multi-active, worst-case crosstalk exhibited by the connector shown in  FIGS. 13A-13D . 
         FIG. 17  depicts an example contact arrangement of an electrical connector according to another embodiment in which differential signal contacts are arranged edge-to-edge. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1A and 1B  depict isometric and side views, respectively, of a prior art connector system  100 . The connector system  100  includes a plug connector  102  mated to a receptacle connector  104 . The plug connector  102  may be mounted to a first substrate, such as a printed circuit board  106 . The receptacle connector  104  may be mounted to a second substrate, such as a printed circuit board  108 . The plug connector  102  and the receptacle connector  104  are shown as vertical connectors. That is, the plug connector  102  and the receptacle connector  104  each define mating planes that are generally parallel to their respective mounting planes. 
     The plug connector  102  may include a connector housing, a base  110 , leadframe assemblies  126 , and electrical contacts  114 . The connector housing of the plug connector  102  may include an interface portion  105  that defines one or more grooves  107 . As will be further discussed below, the grooves  107  may receive a portion of the receptacle connector  104  and, therefore, may help provide mechanical rigidity and support to the connector system  100 . 
     Each of the leadframe assemblies  126  of the plug connector  102  may include a first leadframe housing  128  and a second leadframe housing  130 . The first leadframe housing  128  and the second leadframe housing  130  may be made of a dielectric material, such as plastic, for example. The leadframe assemblies  126  may be insert molded leadframe assemblies (IMLAs) and may house a linear array of electrical contacts  114 . For example, as will be further discussed below, the array of electrical contacts  114  may be arranged edge-to-edge in each lead frame assembly  126 , i.e., the edges of adjacent electrical contacts  114  may face one another. 
     The electrical contacts  114  of the plug connector  102  may each have a cross-section that defines two opposing edges and two opposing broadsides. Each electrical contact  114  may also define at least three portions along its length. For example, as shown in  FIG. 1B , each electrical contact  114  may define a mating end  116 , a lead portion  118 , and a terminal end  121 . The mating end  116  may be blade-shaped, and may be received by a respective electrical contact  136  of the receptacle connector  104 . The terminal end  121  may be “compliant” and, therefore, may be press-fit into an aperture  124  of the base  110 . The terminal end  121  may electrically connect with a ball grid array (BGA)  125  on a substrate face  122  of the base  110 . The lead portion  118  of the electrical contact  114  may extend from the terminal end  121  to the mating end  116 . 
     The base  110  of the plug connector  102  may be made of a dielectric material, such as plastic, for example. The base  110  may define a plane having a connector face  120  and the substrate face  122 . The plane defined by the base  110  may be generally parallel to a plane defined by the printed circuit board  106 . As shown in  FIG. 1A , the connector face  120  of the base  110  may define the apertures  124  that receive the terminal ends  121  of the electrical contacts  114 . The substrate face  122  of the base  110  may include the BGA  125 , which may electrically connect the electrical contacts  114  to the printed circuit board  106 . 
     The receptacle connector  104  may include a connector housing, a base  112 , leadframe assemblies  132 , and electrical contacts  136 . The connector housing of the receptacle connector  104  may include an interface portion  109  that defines one or more ridges  111 . Upon mating the plug connector  102  and the receptacle connector  104 , the ridges  111  on the connector housing of the receptacle connector  104  may engage with the grooves  107  on the connector housing of the plug connector  102 . Thus, as noted above, the grooves  107  and the ridges  111  may provide mechanical rigidity and support to the connector system  100 . 
     Each of the leadframe assemblies  132  of the receptacle connector  104  may include a leadframe housing  133 . The leadframe housing  133  may be made of a dielectric material, such as plastic, for example. Each of the leadframe assemblies  132  may be an insert molded leadframe assembly (IMLAs) and may house a linear array of electrical contacts  136 . For example, the array of electrical contacts  136  may be arranged edge-to-edge in the leadframe assembly  132 , i.e., the edges of adjacent electrical contacts  136  may face one another. 
     Like the electrical contacts  114 , the electrical contacts  136  of the receptacle connector  104  may have a cross-section that defines two opposing edges and two opposing broadsides. Each electrical contact  136  may define at least three portions along its length. For example, as shown in  FIG. 1B , each electrical contact  136  may define a mating end  141 , a lead portion  144 , and a terminal end  146 . The mating end  141  of the electrical contact  136  may be any receptacle for receiving a male contact, such as the blade-shaped mating end  116  of the electrical contact  114 . For example, the mating end  141  may include at least two-opposing tines  148  that define a slot therebetween. The slot of the mating end  141  may receive the blade-shaped mating end  116  of the electrical contacts  114 . The width of the slot (i.e., the distance between the opposing tines  148 ) may be smaller than the thickness of the blade-shaped mating end  116 . Thus, the opposing tines  148  may exert a force on each side of the blade-shaped mating end  116 , thereby retaining the mating end  116  of the of the electrical contact  114  in the mating end  141  of the electrical contact  136 . Alternatively, as shown in  FIG. 1A , the mating end  141  may include a single tine  148  that is configured to make contact with one side of the blade-shaped mating end  116 . 
     The terminal end  146  of the electrical contact  136  may be “compliant” and, therefore, may be press-fit into an aperture (not shown) of the base  112 . The terminal end  146  may electrically connect with a ball grid array (BGA)  142  on a substrate face  140  of the base  112 . The lead portion  144  of each electrical contact  136  may extend from the terminal end  146  to the mating end  141 . 
     The base  112  of the receptacle connector  104  may be made of a dielectric material, such as plastic, for example. The base  112  may define a plane having a connector face  138  and the substrate face  140 . The plane defined by the base  112  may be generally parallel to a plane defined by the printed circuit board  108 . The connector face  138  may define apertures (not shown) for receiving the terminal ends  146  of electrical contacts  136 . Although the apertures of the base  112  are not shown in  FIGS. 1A and 1B , the apertures in the connector face  138  of the base  112  may be the same or similar to the apertures  124  in the connector face  120  of the base  110 . The substrate face  140  may include the BGA  142 , which may electrically connect the electrical contacts  136  to the printed circuit board  108 . 
       FIG. 1C  depicts a contact arrangement  190 , viewed from the face of the plug connector  102 , in which the electrical contacts  114  are arranged in linear arrays. As shown in  FIG. 1C , the electrical contacts  114  may be arranged in a 5×4 array, though it will be appreciated that the plug connector  102  may include any number of the electrical contacts  114  arranged in various configurations. As shown, the plug connector  102  may include contact rows  150 ,  152 ,  154 ,  156 ,  158  and contact columns  160 ,  162 ,  164 ,  166 . 
     As noted above, each of the electrical contacts  114  may have a cross-section that defines two opposing edges and two opposing broadsides. The electrical contacts  114  may be arranged edge-to-edge along each of the columns  160 ,  162 ,  164 ,  166 . In addition, the electrical contacts  114  may be arranged broadside-to-broadside along each of the rows  150 ,  152 ,  154 ,  156 ,  158 . As shown in  FIG. 1C , the broadsides of the electrical contacts  114  in the rows  150 ,  154 ,  158  may be smaller than the broadsides of the electrical contacts  114  in the rows  152 ,  156 . Each of the electrical contacts  114  may be surrounded on all sides by a dielectric  176 , which may be air. 
     The electrical contacts  114  in the plug connector  102  may include ground contacts G and signal contacts S. As shown in  FIG. 1C , the rows  150 ,  154 ,  158  of the plug connector  102  may include all ground contacts G. The rows  152 ,  156  of the plug connector  102  may include both ground contacts G and signal contacts S. For example, the electrical contacts  114  in the rows  152 ,  156  may be arranged in a G-S-S-G pattern. As noted above, the electrical contacts  114  may be arranged broadside-to-broadside along each of the rows  150 ,  152 ,  154 ,  156 ,  158 . Accordingly, adjacent signal contacts S in rows  152 ,  156  may form broadside coupled differential signal pairs, such as the differential signal pairs  174  shown in  FIG. 1C . 
       FIGS. 2A and 2B  depict isometric and side views, respectively, of a connector system  200  according to an embodiment. The connector system  200  may include a plug connector  202  mated to the receptacle connector  104 . The plug connector  202  may be mounted to the printed circuit board  106 . The receptacle connector  104  may be mounted to the printed circuit board  108 . The plug connector  202  and the receptacle connector  104  are shown as vertical connectors. However, it will be appreciated that either or both of the plug connector  202  and the receptacle connector  104  may be right-angle connectors in alternative embodiments. 
     The plug connector  202  may include the base  110 , leadframe assemblies  126 , and electrical contacts  114 . As shown in  FIG. 2B , the plug connector  202  may further include a non-air dielectric, such as a dielectric material  204 , positioned between adjacent leadframe assemblies  126 . In particular, the dielectric material  204  may be positioned between the adjacent leadframe assemblies that house one or more signal contacts S. The dielectric material  204  may be made from any suitable material, such as plastic, for example. The dielectric material  204  may be molded as part of the leadframe assemblies  126 . Alternatively, the dielectric material  204  may be molded independent of the leadframe assemblies  126  and subsequently inserted therebetween. 
       FIG. 2C  depicts a side view of the dielectric material  204 . As shown in  FIG. 2C , the dielectric material  204  may include header portions  205   a ,  205   b , that extend substantially parallel to one another. The dielectric material may further include interconnecting portions  206   a ,  206   b  that extend substantially parallel to one another and substantially perpendicular to the header portions  205   a ,  205   b . The interconnecting portions  206   a ,  206   b  may connect the header portion  205   a  to the header portion  205   b.    
     As noted above with respect to  FIGS. 2A and 2B , the dielectric material  204  may be disposed between adjacent leadframe assemblies  126  having signal contacts S (i.e., the inner leadframe assemblies  126  shown in  FIGS. 2A and 2B ). More specifically, the header portion  205   a  of the dielectric material  204  may be adjacent to the first leadframe housing  128  and may extend along a length thereof. The header portion  205   b  of the dielectric material  204  may be adjacent to the second leadframe housing  130  and may extend along a length thereof. Thus, the header portions  205   a ,  205   b  may be disposed adjacent to at least a portion of each electrical contact  114  in the inner leadframe assemblies  126 . The interconnecting portions  206   a ,  206   b  of the dielectric material  204  may extend substantially parallel to the electrical contacts  114  in the inner leadframe assemblies  126 . In particular, as will be further discussed below, the interconnecting portions  206   a ,  206   b  may extend along the lengths of each signal contact housed in the inner leadframe assemblies  126 . 
       FIG. 2D  depicts a contact arrangement  290 , viewed from the face of the plug connector  202 , that includes the linear arrays of electrical contacts  114  and a portion of the dielectric material  204 . Like the contact arrangement depicted in  FIG. 1C , the electrical contacts  114  may be arranged in a 5×4 array and may define contact rows  150 ,  152 ,  154 ,  156 ,  158  and contact columns  160 ,  162 ,  164 ,  166 . The electrical contacts  114  in the plug connector  202  may have a cross-section that defines two opposing edges and two opposing broadsides. The electrical contacts  114  may be arranged edge-to-edge along each of the columns  160 ,  162 ,  164 ,  166 . In addition, the electrical contacts  114  may be arranged broadside-to-broadside along each of the rows  150 ,  152 ,  154 ,  156 ,  158 . The broadsides of the electrical contacts  114  in the rows  150 ,  154 ,  158  may be smaller than the broadsides of the electrical contacts  114  in the rows  152 ,  156 . 
     The electrical contacts  114  in the plug connector  202  may also include ground contacts G and signal contacts S. The rows  150 ,  154 ,  158  of the plug connector  202  may include all ground contacts G, and the rows  152 ,  156  may include both ground contacts G and signal contacts S. For example, the electrical contacts  114  in the rows  152 ,  156  may be arranged in a G-S-S-G pattern. The electrical contacts  114  may be arranged broadside-to-broadside along each of the rows  150 ,  152 ,  154 ,  156 ,  158 . Accordingly, adjacent signal contacts S in rows  152 ,  156  may form broadside coupled differential signal pairs  174 . 
     As shown in  FIG. 2D , the interconnecting portions  206   a ,  206   b  of the dielectric material  204  may define a generally rectangular cross-section and may be positioned between adjacent signal contacts S in the columns  162 ,  164 . That is, the interconnecting portions  206   a ,  206   b  may be positioned between the signal contacts S of each broadside-coupled differential signal pair  174  in the plug connector  202 . In addition, each of the electrical contacts  114  may be surrounded on all sides by the dielectric  176 , which may be different than the dielectric material  204  disposed between the broadside-coupled differential signal pairs  174 . 
     As further shown in  FIG. 2D , the interconnecting portions  206   a ,  206   b  may extend a greater distance than each of the electrical contacts  114  in the direction of the rows  150 ,  152 ,  154 ,  156 ,  158  (i.e., the interconnecting portions  206   a ,  206   b  may be wider than the electrical contacts  114 ), though it will be appreciated that the widths of the interconnecting portions  206   a ,  206   b  may be equal to or less than the widths of the electrical contacts  114  in other embodiments. In addition, the interconnecting portions  206   a ,  206   b  may extend substantially the same distance as each of the electrical contacts  114  in the direction of the contact columns  160 ,  162 ,  164 ,  166  (i.e., the height of each of the interconnecting portions  206   a ,  206   b  may be substantially the same as the heights of the electrical contacts  114  in the contact rows  152 ,  156 ), though it will be appreciated that the heights of the interconnecting portions  206   a ,  206   b  may be greater than or less than the heights of the electrical contacts  114  in other embodiments. 
       FIGS. 3A and 3B  depict isometric and side views, respectively, of a connector system  300  according to another embodiment. The connector system  300  includes a plug connector  302  mated to the receptacle connector  104 . The plug connector  302  may be mounted to the printed circuit board  106 . The receptacle connector  104  may be mounted to the printed circuit board  108 . The plug connector  302  and the receptacle connector  104  are shown as vertical connectors. However, it will be appreciated that either or both of the plug connector  302  and the receptacle connector  104  may be right-angle connectors in alternative embodiments. 
     The plug connector  302  may include the base  110 , leadframe assemblies  126 , and electrical contacts  114 . As shown in  FIG. 3A , the plug connector  302  may further include a commoned ground plate  178  housed in at least one of the leadframe assemblies  126 . The commoned ground plate  178  may be a continuous, electrically conductive sheet that extends along an entire contact column and that is brought to ground, thereby shielding all electrical contacts  114  adjacent to the commoned ground plate  178 . The commoned ground plate  178  may include a plate portion  180 , terminal ends  182 , and mating interfaces  184 . 
     More specifically, the plate portion  180  of the commoned ground plate  178  may be housed within the leadframe assembly  126 , and may extend from the terminal ends  182  to the mating interfaces  184 . As shown in  FIG. 3A , the commoned ground plate  178  may include terminal ends  182  extending from the plate portion  180 , and extending from the second leadframe housing  130  of the leadframe assembly  126 . The terminal ends  182  may be compliant and may, therefore, be press-fit into the apertures  124  of the base  110 . The terminal ends  182  of the commoned ground plate  178  may electrically connect with the BGA  125  on the bottom side  122  of the base  110 . 
     The commoned ground plate  178  may also include mating interfaces  184  extending from the plate portion  180 , and extending above the first leadframe housing  128  of the lead frame assembly  126 . The mating interfaces  184  may be blade-shaped, and may be received by the respective mating ends  141  of the electrical contacts  136 . 
       FIG. 3C  depicts a contact arrangement  390 , viewed from the face of the plug connector  302 , that includes linear arrays of electrical contacts  114  and commoned ground plates  178   a ,  178   b . The electrical contacts  114  and the commoned ground plates  178   a ,  178   b  may be arranged in a 5×4 array and may define contact rows  150 ,  152 ,  154 ,  156 ,  158  and contact columns  160 ,  162 ,  164 ,  166 . Like the contact arrangement depicted in  FIG. 1C , the electrical contacts  114  in the plug connector  302  may have a cross-section that defines two opposing edges and two opposing broadsides. The electrical contacts  114  may be arranged edge-to-edge along each of the columns  162 ,  164 . In addition, the electrical contacts  114  may be arranged broadside-to-broadside along each of the rows  150 ,  152 ,  154 ,  156 ,  158 . The broadsides of the electrical contacts  114  in the rows  150 ,  154 ,  158  may be smaller than the broadsides of the electrical contacts  114  in the rows  152 ,  156 . 
     The commoned ground plates  178   a ,  178   b  may be positioned adjacent to the contact columns  162 ,  164 , respectively. Thus, as shown in  FIG. 3C , the commoned ground plates  178   a ,  178   c  may replace the ground contacts G in the contact columns  160 ,  166  shown in  FIG. 1C . 
     The electrical contacts  114  in the plug connector  302  may include ground contacts G and signal contacts S. The rows  150 ,  154 ,  158  of the plug connector  302  may include all ground contacts G, and the rows  152 ,  156  may include both ground contacts G and signal contacts S. For example, the commoned ground plates  178   a ,  178   b  and the electrical contacts  114  in the rows  152 ,  156  may be arranged in a G-S-S-G pattern. The electrical contacts  114  may be arranged broadside-to-broadside along each of the rows  150 ,  152 ,  154 ,  156 ,  158 . Accordingly, adjacent signal contacts S in rows  152 ,  156  may form broadside coupled differential signal pairs  174 . 
     The commoned ground plates  178   a ,  178   b  may each have a cross-section that is generally rectangular in shape. As shown in  FIG. 3C , the commoned ground plates  178   a ,  178   b  may each extend substantially the entire length of the contact columns  160 ,  162 ,  164 ,  166 . The commoned ground plates  178   a ,  178   b  may also extend substantially the same distance as each of the electrical contacts  114  in the direction of the contact rows (i.e., each of the commoned ground plates  178   a ,  178   b  may have substantially the same width as the electrical contacts  114 ), though it will be appreciated that the widths of the of the commoned ground plates  178   a ,  178   b  may be less than or greater than the widths of the electrical contacts  114  in other embodiments. The electrical contacts  114  and the commoned ground plates  178   a ,  178   b  may be surrounded on all sides by the dielectric  176 . 
       FIGS. 4A and 4B  depict isometric and side views, respectively, of a connector system  400  according to another embodiment. The connector system  400  may include a plug connector  402  mated to the receptacle connector  104 . The plug connector  402  may be mounted to the printed circuit board  106 . The receptacle connector  104  may be mounted to the printed circuit board  108 . The plug connector  402  and the receptacle connector  104  are shown as vertical connectors. However, either or both of the plug connector  402  and the receptacle connector  104  may be right-angle connectors in alternative embodiments. The plug connector  402  may include the base  110 , the leadframe assemblies  126 , the electrical contacts  114 , the commoned ground plates  178   a ,  178   b , and the dielectric material  204 . 
       FIG. 4C  depicts a contact arrangement  490 , viewed from the face of the plug connector  402 , that includes linear arrays of electrical contacts  114 , the commoned ground plates  178   a ,  178   b  and the dielectric material  204 . As shown in  FIG. 4C , the interconnecting portions  206   a ,  206   b  of the dielectric material  204  may define a generally rectangular cross-section and may be positioned between the signal contacts S in the contact columns  162 ,  164 . That is, the interconnecting portions  206   a ,  206   b  may be positioned between the broadside-coupled differential signal pairs  174  in the contact columns  162 ,  164 . In addition, each of the electrical contacts  114  and the commoned ground plates  178   a ,  178   b  may be surrounded on all sides by the dielectric  176 , which may be different than the dielectric material  204  disposed between the broadside-coupled differential signal pairs  174 . 
     As further shown in  FIG. 4C , the commoned ground plates  178   a ,  178   b  may be positioned adjacent to the contact columns  162 ,  164 , respectively. Thus, the commoned ground plates  178   a ,  178   b  may replace the ground contacts G in the contact columns  160 ,  166  shown in  FIG. 1C . The commoned ground plates  178   a ,  178   b  may each have a cross-section that is generally rectangular in shape. As shown in  FIG. 4C , the commoned ground plates  178   a ,  178   b  may each extend substantially the entire length of the contact columns  160 ,  162 ,  164 ,  166 . The commoned ground plates  178   a ,  178   b  may also extend substantially the same distance as each of the electrical contacts  114  in the direction of the contact rows (i.e., each of the commoned ground plates  178   a ,  178   b  may have the same width as the electrical contacts  114 ), though it will be appreciated that the widths of the of the commoned ground plates  178   a ,  178   b  may be less than or greater than the widths of the electrical contacts  114  in other embodiments. 
     It has also been found that the foregoing embodiments break up the coupling wave that moves up the connector causing a dB “suck out” about the 4 GHz region. An object of the plastic is to change the impedance slightly between signal and ground to minimize the coupling wave. The ground plane is to minimize the signal pair coupling to the ground individual pin edge and to provide a continuous ground plane. 
       FIGS. 5A and 5B  depict isometric and rear views, respectively, of a connector  500  according to an embodiment. The connector  500  may be a plug connector or a receptacle connector. The connector  500  may be devoid of ground plates and/or crosstalk shields. The connector  500  may be mounted to a printed circuit board  510 , which may include one or more via holes  512 . The connector  500  is shown as a right-angle connector. However, it will be appreciated that the connector  500  may be a vertical connector in alternative embodiments. 
     The connector  500  may include a connector housing (not shown), one or more leadframe assemblies (not shown), and electrical contacts  502 . Each leadframe assembly may be an IMLA and may house a linear array of the electrical contacts  502 . For example, the electrical contacts  502  in each linear array may be arranged edge-to-edge, i.e., the edges of adjacent electrical contacts  502  may face one another. 
     Each electrical contact  502  may define at least three portions along its length. For example, each electrical contact  502  may define a mating end  544 , a lead portion  546 , and a terminal end  548 . As shown in  FIG. 5A , each mating end  544  may be blade-shaped and may be adapted to be received via a corresponding female contact (not shown). Alternatively, each mating end  544  may include one or more tines that are adapted to mate with one or more sides of a corresponding male contact (not shown). Each terminal end  548  may be configured to attach to the printed circuit board  510  in any suitable manner. For example, each terminal end  548  may be press-fit into one of the via holes  512  defined by the printed circuit board  510 , or may be surface mounted to the printed circuit board  510  with fusible elements such as solder balls. Each lead portion  546  may extend from the terminal end  548  to the mating end  544 . As will be further discussed below, the electrical contacts  502  of the connector  500  may include signal contacts S and/or ground contacts G. 
     The connector  500  may further include a non-air dielectric, such as a dielectric material  508 , positioned between adjacent leadframe assemblies. In particular, the dielectric material  508  may be positioned between adjacent signal contacts S housed by respective adjacent leadframe assemblies. The dielectric material  508  may be made from any suitable material, such as plastic, for example. The dielectric material  508  may be molded as part of the leadframe assemblies, or may be molded independent of the leadframe assemblies and subsequently inserted therebetween. 
       FIG. 5C  depicts a contact arrangement  514 , viewed from the face of the connector  500 , that includes linear arrays of the electrical contacts  502 . The electrical contacts  502  may be arranged in a 5×9 array and may define contact rows  516 ,  518 ,  520 ,  522 ,  524  and contact columns  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542 , though any suitable configuration is consistent with an embodiment. Each column  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542  may correspond to an IMLA. As shown in  FIG. 5C , each electrical contact  502  in the connector  500  may have a cross-section that defines two opposing edges and two opposing broadsides. As further shown in  FIG. 5C , the broadsides of the ground contacts G may be larger than the broadsides of the signal contacts S. For example, the lengths of the broadsides of the ground contacts G in the direction of the columns  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542  may be longer than the lengths of the signal contact S in the same direction. In an embodiment, the lengths of the broadsides of the ground contacts G may be approximately two times greater than the lengths of the broadsides of the signal contacts S. 
     The electrical contacts  502  may be arranged edge-to-edge along each of the columns  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542 . In addition, the electrical contacts  502  may be arranged broadside-to-broadside along each of the rows  516 ,  518 ,  520 ,  522 ,  524 . Adjacent signal contacts S in each of the rows  516 ,  518 ,  520 ,  522 ,  524  may form a pair of differential signal contacts  504 . A ground contact G may be disposed between each pair of differential signal contacts  504  in the rows  516 ,  518 ,  520 ,  522 ,  524 . In addition, the dielectric material  508  may be disposed between the signal contacts S of each pair of differential signal contacts  504 . The dielectric material  508  may be used to increase field strength within the pair of differential signal contacts  504  while not increasing pair-to-pair coupling, crosstalk, and/or noise. Moreover, the ground contacts G and the signal contacts S may be surrounded on all sides by a dielectric  506 , which may be air. 
     Referring back to  FIG. 5A , the dielectric material  508  may extend along a length of the respective signal contacts S in each pair of differential signal contacts  504  (i.e., from approximately the mating end  544  to the terminal end  548  of each signal contact S). Moreover, the signals contacts S of a respective pair of differential signal contacts  504  may have substantially equal lengths as measured between the mating ends  544  and the terminal ends  548  of the signal contacts S. Thus, each pair of differential signal contacts  504  may exhibit approximately zero signal skew. 
     Each of the contact columns  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542  may define a contact pattern, i.e., an arrangement of ground contacts G and signal contacts S. For example, the electrical contacts  502  in the column  526  may be arranged (moving from top to bottom) in a G-S-S-G-S pattern. The electrical contacts  502  in the column  528  may be arranged in a S-G-S-S-G pattern, though it will be appreciated that the contact pattern in the column  528  may be the same as the contact pattern in the column  526  when viewed from bottom to top. The electrical contacts  502  in the column  530  may be arranged in a S-S-G-S-S pattern, which may be different from the respective contact patterns in the columns  526 ,  528 . 
     The contact patterns in the columns  526 ,  528 ,  530  may be repeated in the remaining columns, i.e., the column  532  may have the same contact pattern as the column  526 , the column  534  may have the same contact pattern as the column  528 , the column  536  may have the same contact pattern as the column  530 , and so on. Thus, each pair of differential signal contacts  504  in the row  518  may be offset (along the row-direction) by one full column pitch from the nearest pair of differential signal contacts  504  in the row  516 . Similarly, each pair of differential signal contacts  504  in the row  520  may be offset (along the row-direction) by one full column pitch from the nearest pair of differential signal contacts  504  in the row  518 . It will be appreciated that some of the signal contacts S may be neutral contacts, or “extra pins,” and may not be needed for the formation of a pair of differential signal contacts  504 . 
     As shown in  FIG. 5C , one of the signal contacts S from each pair of differential signal contacts  504  in the rows  516 ,  518 ,  520 ,  522 ,  524  may form an array defined by an imaginary line  550 . For example, the line  550  may extend from an approximate center point on a side of a signal contact S in the column  528  to an approximate center point on the same side of another signal contact S in the column  536 . Similarly, the ground contacts G in rows  516 ,  518 ,  520 ,  522 ,  524  may also form an array defined by an imaginary line  552 . For example, the line  552  may extend from an approximate center point on a side of a ground contact G in the column  532  to an approximate center point on the same side of another ground contact G in the column  540 . 
     It will be appreciated that the imaginary lines  550 ,  552  may extend from any suitable point on the same sides of the signal contact S and the ground contacts G, respectively. It will be further appreciated that the imaginary lines  550 ,  552  may each define an oblique angle with respect to the direction of the columns  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542 . The oblique angles defined by the lines  550 ,  552  may be substantially the same or may differ from one another. As shown in  FIG. 5C , the array formed along the line  550  by the pairs of differential signal contacts  504  may be disposed between two arrays formed along respective lines  552  by the ground contacts G. 
     The offset of the ground contacts G from row-to-row may be none, less than a column pitch, equal to a column pitch, or more than a column pitch. Similarly, the offset of the pairs of differential signal contacts  504  from row-to-row may be none, less than a column pitch, equal to a column pitch, or more than a column pitch. A row-to-row centerline spacing A may be about 1.4 mm to 2.5 mm, with approximately 2 mm the preferred spacing. A column-to-column centerline spacing B may be about 1.3 mm to 2.5 mm, with approximately 1.8 mm the preferred spacing. A ground-to-ground spacing C in each column may be about 3.9 mm to 6 mm, with approximately 5.4 mm the preferred spacing. A signal-to-signal spacing D in each column may be about 1.2 mm, but can be in a range of about 0.3 mm to 2 mm. A material thickness E of the ground contacts G and/or the signal contacts S may be in a range of 0.2 mm to 0.4 mm, with approximately 0.35 mm the preferred thickness. A height F of each ground contact G is preferably about 2.4 mm, but the height F may range from about 1 mm to 2.9 mm. A spacing J between a ground contact G and an adjacent signal contact S in a column may be about 0.4 mm, but can be in a range of 0.2 mm to 0.7 mm. A gap distance H between signal contacts S that define a pair of differential signal contacts  504  is about 0.2 mm to 2.5 mm, with a gap distance of about 1.8 mm preferred with the dielectric material  508  disposed between the signal contacts S that form the pair. However, the signal contacts S in a column may be offset from the array centerline spacing by a material stock thickness or more, with a approximate 0.2 mm to 0.3 mm offset in opposite directions preferred. 
     In an embodiment, the column  528  may include a first signal contact S and a second signal contact S arranged edge-to-edge along the column  528 . The column  526  may include a third signal contact S adjacent to the first signal contact S in the column  528 . The column  530  may include a fourth signal contact S adjacent to the second signal contact S in the column  528 . As shown in  FIG. 5C , the first and third signal contacts may be arranged broadside-to-broadside and the second and fourth signal contacts may be arranged broadside-to-broadside in a direction substantially perpendicular to the column  528 . The first and third signal contacts may define a first pair of differential signal contacts  504  and the second and fourth signal contacts may define a second pair of differential signal contacts  504 . As further shown in  FIG. 5C , the first and second pairs of differential signal contacts  504  may be offset from one another in the direction substantially perpendicular to the column  528 . 
       FIG. 6  is a comparison plot  600  of differential insertion loss versus frequency exhibited by four pairs of differential signal contacts  504  in the connector  500 . As shown in  FIG. 6 , the connector  500  may exhibit an insertion loss suck out of approximately −1.5 dB in the 4 to 6 GHz frequency range. 
       FIG. 7  is a comparison plot  700  of differential impedance versus time exhibited by the four pairs of the differential signal contacts  504  in the connector  500 . As shown in  FIG. 7 , the connector  500  may exhibit a differential impedance of approximately 100 ohms plus or minus 6%. 
       FIG. 8  is a table  800  summarizing multi-active, worst-case crosstalk exhibited by the four pairs of differential signal contacts  504  in the connector  500 . As shown in  FIG. 8 , the connector  500  may exhibit a multi-active, worst case crosstalk in a range of about 2.6% to 5.5%. Far end crosstalk is shown in the upper two quadrants of  FIG. 8 , and near end crosstalk is shown in the lower two quadrants of  FIG. 8 . Although rise time is indicated as 50 (10-90%) picoseconds, the measurement may be between 35-1000 (10-90% or 20-80%) picoseconds. These values generally may correspond to data transfer rates of about ten or more Gigabits per second to less than 622 Megabits per second. 
       FIGS. 9A and 9B  depict isometric views of a connector  900  according to another embodiment.  FIG. 9C  depicts a contact arrangement  902 , viewed from the face of the connector  900 , that includes linear arrays of the electrical contacts  502 . Like the connector  500 , the connector  900  may be devoid of ground plates and/or crosstalk shields. The connector  900  may be a right-angle connector that is mounted to the printed circuit board  510 , though it will be appreciated that the connector  900  may be a vertical connector in alternative embodiments. 
     The connector  900  generally may include the same features and/or elements as the connector  500 , such as one or more leadframe assemblies (not shown) for housing linear arrays of the electrical contacts  502  and a dielectric material  508  disposed between adjacent signal contacts S. As shown in  FIGS. 9A and 9B , the dielectric material  508  may extend along a length of the respective signal contacts S in each pair of differential signal contacts  504 . In addition, the connector  900  may have the same or similar contact and contact spacing dimensions as the connector  500 . 
     As shown in  FIG. 9C , the connector  900  may differ from the connector  500  in that the connector  900  may be devoid of any ground contacts G. More specifically, the contact arrangement  902  may include one or more signal contacts S arranged edge-to-edge along each of the columns  526 ,  528 ,  530 ,  532 ,  534 ,  536 ,  538 ,  540 ,  542 . In addition, the signal contacts S may be arranged broadside-to-broadside along each of the rows  516 ,  518 ,  520 ,  522 ,  524 . Adjacent signal contacts S in each of the rows  516 ,  518 ,  520 ,  522 ,  524  may form pairs of differential signal contacts  504 . Unlike the connector  500 , a ground contact G may not be disposed between each pair of differential signal contacts  504  in the rows  516 ,  518 ,  520 ,  522 ,  524  of the connector  900 . 
       FIG. 10  is a comparison plot  1000  of differential insertion loss versus frequency exhibited by four pairs of differential signal contacts  504  in the connector  900 . As shown in  FIG. 10 , the connector  900  may exhibit an insertion loss suck out of approximately −0.5 dB in the 4 to 6 GHz frequency range. 
       FIG. 11  is a comparison plot  1100  of differential impedance versus time exhibited by the four pairs of the differential signal contacts  504  in the connector  900 . As shown in  FIG. 11 , the differential impedance for all but one of the pairs of differential signal contacts  504  may be approximately 100 ohms plus or minus 10%. It will be appreciated that the differential impedance may be adjusted (i.e., matched to a system impedance) by moving the signal contacts S that form a pair of differential signal contacts  504  closer together or farther apart, by increasing or decreasing the width of the signal contacts S, and/or by increasing or decreasing a dielectric constant in the gap between the signal contacts S. 
       FIG. 12  is a table  1200  summarizing multi-active, worst-case crosstalk exhibited by the four pairs of differential signal contacts  504  in the connector  900 . As shown in  FIG. 12 , the connector  900  may exhibit a multi-active, worst case crosstalk in a range of about 2.7% to 4.1%. Far end crosstalk is shown in the upper two quadrants of  FIG. 12 , and near end crosstalk is shown in the lower two quadrants of  FIG. 12 . 
       FIGS. 13A and 13B  depict isometric views of a connector  1300  according to another embodiment.  FIG. 13C  depicts a rear view of the connector  1300 .  FIG. 13D  depicts a contact arrangement  1302 , viewed from the face of the connector  1300 , that includes linear arrays of the electrical contacts  502 . Like the connector  500 , the connector  1300  may be devoid of ground plates and/or crosstalk shields. The connector  1300  may be a right-angle connector that is mounted to the printed circuit board  510 , though it will be appreciated that the connector  1300  may be a vertical connector in alternative embodiments. 
     The connector  1300  generally may include the same features and/or elements as the connector  500 , such as one or more leadframe assemblies (not shown) for housing linear arrays of the electrical contacts  502 . Each linear array may include the ground contacts G and the signal contacts S. In addition, the connector  1300  may have the same or similar contact and contact spacing dimensions as the connector  500  as well as the same or similar contact arrangements. 
     As shown in  FIG. 13D , the connector  1300  may differ from the connector  500  in that the connector  1300  may not include the dielectric material  508  disposed between adjacent signal contacts S that form a pair of differential signal contacts  504 . Moreover, a row-to-row centerline spacing K may be about 1.4 mm to 3, with 1.65 mm to 2 mm being the preferred spacing. A column-to-column centerline spacing L is about 1.3 mm to 2.5 mm, with 1.4 mm to 1.5 mm being the preferred spacing. 
       FIG. 14  is a comparison plot  1400  of differential insertion loss versus frequency exhibited by four pairs of differential signal contacts  504  in the connector  1300 . As shown in  FIG. 14 , the connector  1300  may exhibit an insertion loss of less than −0.5 dB up to 20 GHz and approximately zero suck out in a 0 to 20 GHz frequency range. In addition, the insertion loss values demonstrate minimal tapering in the 0 to 20 GHz frequency range. Consequently, the insertion loss for one or more of the pairs of differential signal contacts  504  may remain below −2 dB or less up to at least 40 GHz. 
       FIG. 15  is a comparison plot  1500  of differential impedance versus time exhibited by the four pairs of the differential signal contacts  504  in the connector  1300 . As shown in  FIG. 15 , the differential impedance for all but one of the pairs of differential signal contacts  504  may be approximately 100 ohms plus or minus 10%. As noted above, the differential impedance may be adjusted (i.e., matched to a system impedance) by moving the signal contacts S that form a pair of differential signal contacts  504  closer together or farther apart, by increasing or decreasing the width of the signal contacts S, and/or by increasing or decreasing a dielectric constant in the gap between the signal contacts S. 
       FIG. 16  is a table  1600  summarizing multi-active, worst-case crosstalk exhibited by the four pairs of differential signal contacts  504  in the connector  1300 . As shown in  FIG. 16 , the connector  1300  may exhibit a multi-active, worst case crosstalk in a range of about 0.3% to 2.1%. Far end crosstalk is shown in the upper two quadrants of  FIG. 16 , and near end crosstalk is shown in the lower two quadrants of  FIG. 16 . 
     In one or more of the foregoing embodiments, at least a portion of the electrical contacts may be insert molded in plastic. Moreover, the electrical connectors may be configured for flat rock PCB press-fit insertion. For example, one or more linear arrays of electrical contacts may be laminated. Each laminated linear array may then be combined together to form a solid body or a collection of individual wafers. Alternatively, a four, five, or six sided box may be created around the electrical contacts. The interior of the box may then be filled with air, plastic, PCB material, or any combination thereof. The electrical connector may be mounted to a printed circuit board via solder balls, fusible elements, solder fillets, and the like. 
       FIG. 17  depicts a contact arrangement  1700  viewed from the face of an electrical connector according to another embodiment in which differential signal contacts are arranged edge-to-edge. The contact arrangement  1700  may include linear arrays of electrical contacts  1732 , which may include the ground contacts G and the signal contacts S. As shown in  FIG. 17 , the electrical contacts  1732  may be arranged in a 6×9 array and may define contact rows  1702 ,  1704 ,  1706 ,  1708 ,  1710 ,  1712  and contact columns  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  1730 , though any suitable configuration is consistent with an embodiment. Each column  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  1730  may correspond to an IMLA. As shown in  FIG. 17 , each electrical contact  1732  in the connector may have a cross-section that defines two opposing edges and two opposing broadsides. As further shown in  FIG. 17 , the broadsides of the ground contacts G may be larger than the broadsides of the signal contacts S. For example, in an embodiment, the broadsides of the ground contacts G may be approximately two times greater than the broadsides of the signal contacts S. 
     The electrical contacts  1732  may be arranged edge-to-edge along each of the columns  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  1730 . In addition, at least a portion of the electrical contacts  1732  may be arranged broadside-to-broadside along each of the rows  1702 ,  1704 ,  1706 ,  1708 ,  1710 ,  1712 . Adjacent signal contacts S in each of the columns  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  1730  may form a pair of differential signal contacts  1734 . A ground contact G may be disposed between each pair of differential signal contacts  1734  in the columns  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  1730 . The ground contacts G and the signal contacts S may be surrounded on all sides by the dielectric  506 . 
     Each of the contact columns  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  1730  may define a contact pattern. For example, the electrical contacts  1732  in the column  1714  may be arranged (moving from top to bottom) in a G-S-S-G-S-S pattern. The electrical contacts  1732  in the column  1716  may be arranged in a S-S-G-S-S-G pattern, though it will be appreciated that the contact pattern in the column  1716  may be the same as the contact pattern in the column  1714  when viewed from bottom to top. The electrical contacts  1732  in the column  1718  may be arranged in a S-G-S-S-G-S pattern, which may be different from the respective contact patterns in the columns  1714 ,  1716 . 
     The contact patterns in the columns  1714 ,  1716 ,  1718  may be repeated in the remaining columns, i.e., the column  1720  may have the same contact pattern as the column  1714 , the column  1722  may have the same contact pattern as the column  1716 , the column  1724  may have the same contact pattern as the column  1718 , and so on. It will be appreciated that some of the signal contacts S may be neutral contacts, or “extra pins,” and may not be needed for the formation of a pair of differential signal contacts  1734 . 
     As shown in  FIG. 17 , the ground contacts G in rows  1702 ,  1704 ,  1706 ,  1708 ,  1710 ,  1712  may form one or more arrays defined by an imaginary line  1736 . For example, one of the lines  1736  may extend from an approximate center point on a side of a ground contact G in the column  1716  to an approximate center point on the same side of another ground contact G in the column  1726 . It will be appreciated that the imaginary lines  1736  may extend from any suitable point on the same sides of the ground contacts G. Each imaginary line  1736  may define an oblique angle with respect to the direction of the columns  1714 ,  1716 ,  1718 ,  1720 ,  1722 ,  1724 ,  1726 ,  1728 ,  17302 . The oblique angles defined by each line  1736  may be substantially the same or may differ from one another.