Abstract:
A differential pair connector has a housing floor, an array of differential pairs passing through the housing floor, and a conductive grid integrated into the housing floor for reducing crosstalk between the differential pairs. The conductive grid can have various structures, such as conductive inserts, plated regions and/or a conductive housing floor surrounding non-conductive inserts protecting the differential pins. Although any suitable means can be used to fasten the conductive grid into the housing floor, the grid is preferably press fitted into the top of the housing floor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application is a continuation of U.S. Serial application Ser. No. 12/535,102, filed Aug. 4, 2009, now U.S. Pat. No. ______, which in turn is a continuation of U.S. Serial application Ser. No. 11/771,666, filed Jun. 29, 2007, now U.S. Pat. No. 7,632,149, which claims the benefit of U.S. Provisional Patent Application Nos. 60/817,857, filed Jun. 30, 2006, and 60/818,140 filed Jun. 30, 2006, all of which are incorporated by reference in their entireties. 
         [0002]    This application is related to U.S. patent application Ser. No. 11/771,739 “Differential Pair Electrical Connector Having Crosstalk Shield Tabs,” filed on Jun. 29, 2007, assigned to the same assignee and identifying Craig A. Bixler, John C. Laurx, Neil A. Martin and Tom Carlson as the inventors. This related application is incorporated by reference in its entirety as though fully set forth herein for everything it describes. 
     
    
     TECHNICAL FIELD 
       [0003]    The present invention relates generally to electrical connectors, and more specifically, to high-frequency electrical connectors where signal crosstalk is a performance consideration. 
       BACKGROUND 
       [0004]    Electronic devices continue to shrink in size, yet increase in speed and complexity. This has lead to the widespread availability of relatively small electronic components capable of driving high-speed signals (e.g., above one GHz) over printed circuit board (PCB) tracks. The increased use of these small, high-speed components has created a significant demand for high performance electrical connectors that can support high frequencies and denser PCB track configurations. 
         [0005]    In response to this demand, certain types of high performance electrical connectors have been developed. One type of high performance connector is a GbX® Style connector, available from Molex, Inc. of Lisle, Ill.  FIGS. 1-2  are partial top and bottom perspective views, respectively, of a conventional GbX® backplane connector  10 . 
         [0006]    The backplane connector  10  includes a non-conductive housing having a housing floor  12  with header sidewalls (not shown) extending perpendicularly from the housing floor  12  substantially parallel to each other. The partial views of  FIGS. 1-2  show an exemplary 4×2 array of differential pins  13  and three ground plane shields  14  interposed between rows of differential pin pairs  11 . Each of the pin pairs  11  can receive or transmit a differential signal. The differential-pair pins  13  and ground shields  14  are press-fitted into the floor  12  so as to pass through the floor  12 . Each of the differential pins  13  has a generally flat upper portion  19  and an eye-of-the-needle compliant pin  23  as a lower portion. Each of the ground shields  14  has a generally flat upper blade  15  and one or more lower eye-of-the-needle pins  17 . 
         [0007]    For purposes of convention, the partial views of  FIGS. 1-2  show two “columns” of differential pins  13 . Each column has four metal differential pins  13 , which are part of a larger column in the two-dimensional differential-pair pin array. Each ground shield  14  is made up of a metal plate  15  and is connected to ground to provide shielding between “rows” of the pin pairs  11 . 
         [0008]    Transmitting high speed signals over differential pair channels has become an increasingly popular technique for high bandwidth transmission between printed circuit boards (PCBs). In a typical high bandwidth system, “daughter card” PCBs are connected to a “backplane” using mated connectors. The backplane is itself a layered circuit board having, among other things, differential pair tracks formed therein for carrying high frequency signals between daughter cards. 
         [0009]    In such systems, a variable that effects transmission bandwidth is crosstalk. Generally, crosstalk is the electrical interference in a channel caused by a signal traveling through a neighboring channel. Under some circumstances, the presence of unwanted crosstalk degrades system performance and negatively impacts bandwidth. Thus, in differential pair systems, it is important that daughter cards and backplanes are designed to reduce the amount of crosstalk between differential pairs. It is also highly desirable to have PCB connectors that reduce crosstalk. 
         [0010]    In view of the foregoing, there is a substantial need for an electrical connector that significantly reduces crosstalk in high signal density, high bandwidth applications. 
       SUMMARY 
       [0011]    It is an advantage of the present invention to provide an improved differential pair connector that includes means for significantly reducing crosstalk between differential pairs. It is a further advantage of the present invention to provide an improved connector that can be implemented with the mating and physical characteristics of a conventional connector type, such as a GbX® connector. 
         [0012]    In accordance with an exemplary embodiment of the present invention, a differential pair connector has a housing floor, an array of differential pairs passing through the housing floor, and a conductive grid integrated into the housing floor for reducing crosstalk between the differential pairs. The conductive grid can have various structures, such as conductive inserts, plated regions and/or a conductive housing floor surrounding non-conductive inserts protecting the differential pins. 
         [0013]    Other aspects, features, embodiments, processes and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional features, embodiments, processes and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    It is to be understood that the drawings are solely for purpose of illustration and do not define the limits of the invention. Furthermore, the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views. 
           [0015]      FIG. 1  is a top perspective view of a prior art backplane connector. 
           [0016]      FIG. 2  is a bottom perspective view of the prior art backplane connector shown in  FIG. 1 . 
           [0017]      FIG. 3  is a bottom perspective view of a backplane connector in accordance with an exemplary embodiment of the present invention. 
           [0018]      FIG. 4  is a skeletal perspective view of a backplane connector including a first style of crosstalk shielding wedges. 
           [0019]      FIG. 5  is a skeletal perspective view of a backplane connector having a second style of crosstalk shielding wedges. 
           [0020]      FIG. 6  is a perspective view of one of the crosstalk reduction grids shown in  FIG. 1 . 
           [0021]      FIG. 7  is a bottom perspective view of a backplane connector in accordance with a further embodiment of the present invention. 
           [0022]      FIG. 8  is a top perspective view of the crosstalk reduction panel shown in  FIG. 7 . 
           [0023]      FIG. 9  is a perspective view of a GbX®-style backplane connector in accordance with a preferred embodiment of the present invention. 
           [0024]      FIG. 10  is a top plan view of the GbX®-style backplane connector shown in  FIG. 9 . 
           [0025]      FIGS. 11A-B  show front and back perspective views, respectively, of the backplane connector housing of the connector shown in  FIGS. 9-10 , omitting differential pins, guide pins and ground shields. 
           [0026]      FIG. 12  is a top plan view of the GbX®-style backplane connector housing shown in  FIGS. 11A-B . 
           [0027]      FIG. 13  is a bottom plan view of the GbX®-style backplane connector housing shown in  FIGS. 11A-B . 
           [0028]      FIG. 14  is a first cross-sectional view of the GbX®-style backplane connector housing along section V-V of  FIG. 12 . 
           [0029]      FIG. 15  is a second cross-sectional view of the GbX®-style backplane connector housing along section Z-Z of  FIG. 12 . 
           [0030]      FIGS. 16A-B  are perspective views of the crosstalk reduction grid included in the backplane connector shown in  FIGS. 9-10 . 
           [0031]      FIGS. 17-19  are various views of the crosstalk reduction grid of  FIGS. 16A-B . 
           [0032]      FIG. 20  is a partial cross-sectional view of the GbX®-style backplane connector along section Y-Y of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    The following detailed description, which references to and incorporates the drawings, describes and illustrates one or more specific embodiments of the invention. These embodiments, offered not to limit but only to exemplify and teach the invention, are shown and described in sufficient detail to enable those skilled in the art to practice the invention. Thus, where appropriate to avoid obscuring the invention, the description may omit certain information known to those of skill in the art. 
         [0034]      FIG. 3  is a bottom perspective view of a backplane connector  20  in accordance with an exemplary embodiment of the present invention. Although the invention is not limited to any particular type of electrical connector, the exemplary backplane connector  20  is preferably a GbX®-style connector having plural differential pair conductive pins  13  and ground planes  14  press fitted into a non-conductive housing floor  12 . To reduce crosstalk between differential pairs  11 , the connector  20  includes one or more electrically-conductive grids  22 ,  24  integrated into the housing floor  12  between the differential pairs  11 . The grids  22 ,  24  are connected to ground or some other suitable common potential to provide additional electromagnetic shielding between differential pairs  11 . 
         [0035]    In the example shown, the conductive grids  22 ,  24  insert into the bottom of the housing floor  12 . Preferably, the housing floor  12  includes hollow cores formed between differential pairs  11  adapted to frictionally receive at least part of the conductive grids  22 ,  24 . The conductive grids  22 ,  24  extend into the thickness of the floor  12  between adjacent columns of differential pairs  11 . This provides additional ground plane shielding around each differential pair  11 , and when combined with the existing ground shields  14 , the shielding extends in both dimensions of the differential pin array within the backplane housing floor  12 . This additional shielding significantly reduces crosstalk between differential pairs  13 . 
         [0036]      FIG. 3  illustrates two different types of conductive grids  22 ,  24 . The first type of grid  22  includes individual conductive wedges (e.g., conductive wedges  31  of  FIG. 4  or conductive wedges  42  of  FIG. 5 ) that are inserted into the housing floor  12  between adjacent columns of differential pairs  11 . The second type of grid  24  includes wedges  28  inserted into the floor  12  between adjacent columns of differential pairs  11  and a conductive spine  26  connecting the wedges  28 . The spine  26  extends between pins  23  in a row of differential pairs  13 . The wedges  28  form a plurality of conductive ribs extending perpendicularly from the spine  26  between adjacent columns of the differential pairs  11 . The wedges in either type of grid  22 ,  24  can be the conductive wedges  31  of  FIG. 4 , conductive wedges  42  of  FIG. 5  or any other conductive element of suitable shape and size. 
         [0037]    The conductive grids  22 , 24  can be made of any suitable conductive material, such as an injection molded conductive plastic, metal such as a die cast part, plated metal such as nickel over copper, plated plastic or the like. Any suitable number of conductive grids can be integrated into the backplane housing  12 . 
         [0038]    The backplane connector housing  12  can be made of any suitable electrically non-conductive material, and is preferably made of a thermoplastic formed using conventional injection molding techniques. 
         [0039]      FIG. 4  is a skeletal perspective view of a backplane connector  30  showing a first style of conductive wedges  31 . In this view, the backplane housing is omitted to more clearly show the arrangement of the conductive grid wedges  31 , differential pins  13  and ground planes  14 . Each of the wedges  31  has one or more conductive pipes  32  extending from their tops. The conductive pipes  32  are embedded in the housing floor  12  and provide crosstalk shielding using less conductive material than the solid wedges  42  shown in  FIG. 5 . 
         [0040]      FIG. 5  is a skeletal perspective view of a backplane connector  40  with a second style of crosstalk shielding wedges  42 . In this view, the backplane housing is omitted to more clearly show the arrangement of the conductive grid wedges  42 , differential pins  13  and ground planes  14 . The alternative conductive wedges  42  are solid, and do not include conductive pipes. Instead, the solid portion of the wedges  42  extends through the thickness of the housing floor  12 . 
         [0041]    Conductive wedges  31 ,  42  have a predefined height, which defines how much of the wedge extends into the housing floor  12 . The height is selected to provide a desired amount of crosstalk reduction. The height may be greater than or equal to the entire thickness of the housing floor  12 , or some lesser amount. 
         [0042]      FIG. 6  is a perspective view of the second type of crosstalk reduction grid  24  shown previously in  FIG. 1 . 
         [0043]      FIG. 7  is a bottom perspective view of a backplane connector  50  in accordance with a further exemplary embodiment of the present invention. The backplane connector  50  is a GbX® style module having an 8×10 array of differential pins  13  and three ground plane shields  14  interposed between rows of differential pin pairs  11 . For the sake of clarity, only the first column of pin pairs  13  and only the first two rows of ground shield pins  17  are shown in  FIG. 7 , while the remainder of the pins are omitted from the view. 
         [0044]    The connector  50  includes a non-conductive housing  52  and a conductive crosstalk shielding panel  54  integrated into the housing floor  56 . Although any suitable means can be used to fasten the panel  54  into the housing floor  56 , the shielding panel  54  is preferably press fitted into the bottom of the housing floor  56 . Preferably, the bottom of the housing floor  56  includes hollow contours formed therein to snuggly receive at least part of the panel  54 . Adhesives can also be used to attach the panel  54  to the housing floor  56 . 
         [0045]    The connector housing  52  includes sidewalls  58  extending from the housing floor  56  substantially parallel to each other. The housing sidewalls  58  have guide slots  60  formed on their inside faces for receiving daughter card connector edge guides. 
         [0046]    The conductive panel  54  has an array of thru-hole openings  70  sized and positioned to receive the differential pairs  13 , while keeping the panel  54  electrically isolated from the differential pair conductors  13 . The conductive panel  54  also includes one or more thru-hole openings  72  sized and shaped for receiving the ground plane conductor pins  17  and establishing electrical contact between the panel  54  and the ground plane shields  14 . Thru-holes openings corresponding to the conductive panel openings  70 ,  72  are formed in the housing floor  56 . 
         [0047]    To assemble the connector  50 , the conductive panel  54  is first press fitted into the bottom of the housing floor  56 . The differential-pair pins  13  and ground shields  14  are then press fitted into the floor  56  from the top side so as to pass through the floor  12  and panel openings  70 ,  72 . 
         [0048]      FIG. 8  is a top perspective view of the conductive crosstalk reduction panel  54  shown in  FIG. 7 . The panel  54  includes an array of conductive ribs  74 ,  76  extending upwardly from the panel  54  and spaced apart from each other so as to insert into the housing floor  56  between adjacent columns of differential pairs  13 . The ribs  74 ,  76  extend into the housing floor  56  to provide additional crosstalk shielding. The ribs  74 ,  76  are arranged in four rows  61 . Adjacent rows  61  are connected together by plural eyelets  57 , each eyelet  57  corresponding to a respective ground shield pin  17 . The outer ribs  76  are thicker than the inner ribs  74 . 
         [0049]    The ribs  74 ,  76  have a predefined height, which defines how far the ribs extends into the housing floor  56 . The height is selected to provide a desired amount of crosstalk reduction. The height may be greater than or equal to the entire thickness of the housing floor  56 , or some lesser amount. 
         [0050]    The conductive panel  54  can be made of any suitable electrically conductive material such as die cast or stamped metal, a molded conductive polymer, plated plastic or the like. 
         [0051]    The backplane connector housing  52  can be made of any suitable electrically non-conductive material, and is preferably made of a thermoplastic formed using conventional injection molding techniques. 
         [0052]      FIG. 9  is a perspective view of a GbX®-style backplane connector  400  in accordance with a preferred embodiment of the present invention. The exemplary backplane connector  400  is a GbX®-style module having an 4×20 array of differential pins  402  and a ground plane shield  404  interposed between the two rows of differential pin pairs. The connector  400  includes a non-conductive housing  300  and a conductive crosstalk shielding grid  201  (see FIGS.  10  and  11 A-B) integrated into the housing floor  304 . The conductive grid  201  extends into the thickness of the floor  304  between adjacent columns of differential phi pairs  402  and makes contact with the ground plane shield  404 . This provides additional ground plane shielding around each differential pair, and when combined with the existing ground shields  404 , the shielding extends in both dimensions of the differential pin array within the backplane housing floor  304 . This additional shielding significantly reduces crosstalk between differential pairs. 
         [0053]    In the embodiment shown, the conductive grid  201  has twenty rows of ribs, each row having two opposing ribs. The grid  201  is a two-piece construction that includes two of the twenty-rib conductive grids  200  (see  FIGS. 16A-19 ) inserted into the housing floor  304  in a head-to-toe arrangement. 
         [0054]    Although any suitable means can be used to fasten the conductive grid  201  into the housing floor  304 , the grid  201  is preferably press fitted into the top of the housing floor  304 . During assembly, the grid  201  is fitted into the housing  300  prior to insertion of the differential pins  402  and ground plane shielding  404 . The grid  201  includes protrusions  214  and  210  (see  FIGS. 17 and 19 ) to improve the frictional contact between itself and walls formed in the connector housing floor  304 . Adhesives could also be used to attach the grid  200  to the housing  300 . 
         [0055]    The connector housing  300  includes sidewalls  302  extending from the housing floor  304  substantially parallel to each other. The housing sidewalls  302  have guide slots  308  formed on their inside faces for receiving daughter card connector edge guides. Inwardly protruding ribs  306  are regularly spaced along the inside faces of the sidewalls  302  to form the guide slots  308 . Regularly-spaced exterior fins  312  are formed along the lower edge of each sidewall  302 . 
         [0056]    The connector  400  includes an end portion  314  of the housing  300  upon which are mounted a guide pin  422  and keying pin  420 . The guide pin  422  and keying pin  420  have the same functions and characteristics of those found on conventional GbX® connectors. The guide pin  422  is mounted on a raised platform  318  and the key is mounted on a lower platform  316 . Generally, the guide pin  422  and keying pin  420  are received in mated recepticals of a corresponding GbX® daughter card connector in order to ensure a properly aligned connection, i.e., to reduce the risk of a misaligned or reversed connection. The keying pin  420  is a half cylinder that can be rotated into one of eight different orientations denoted by letters A-H, or removed, giving a total of nine different setting. A keyhole on a corresponding daughter card connector ensures that only a matching daughter card can be connected to the backplane connector  400 . 
         [0057]      FIG. 10  is a top plan view of the backplane connector  400  shown in  FIG. 9 . The conductive grid  200  is inserted into the housing floor  304  so that it is flush with the top of the floor  304  to avoid interfering with the mated characteristics of the backplane connector  400 . 
         [0058]      FIGS. 11A-B  show front and back perspective views, respectively, of the backplane connector housing  300  of the connector  400  shown in  FIGS. 9-10 , without differential pins  402 , guide pins  420 - 422  and ground shield  404 , and with the conductive grid  201  removed. The conductive grid comprises two of the twenty-rib grids  200  shown in  FIGS. 16A-19 . 
         [0059]    The backplane connector housing  300  can be made of any suitable electrically non-conductive material, and is preferably made of a thermoplastic formed using conventional injection molding techniques. 
         [0060]      FIG. 12  is a top plan view of the GbX®-style backplane connector housing  300  shown in  FIGS. 11A-B . The housing floor  304  has formed therein a  4 × 20  array of thru-hole slots  310  adapted to frictionally receive the differential pins  402 . A central trough  320  and lateral thru-hole slots  342  are also formed in the floor and adapted to receive the conductive grid  201 . The trough  342  receives the spine  204  (see  FIGS. 16   a - 19 ) of the grid  201  and the lateral thru-hole slots  342  receive the ribs  202  (see  FIGS. 16   a - 19 ) of the grid  201 . In the bottom of the trough  320  are thru-hole slots  340  aligned along the central axis of the housing  300 . The thru-hole slots  340  are sized and positioned to frictionally receive the lower pins  430  (see  FIG. 20 ) of the ground plane shield  404 . 
         [0061]      FIG. 13  is a bottom plan view of the GbX®-style backplane connector housing  300  shown in  FIGS. 11A-B . The thru-hole slots  310 ,  340 ,  342  allow the differential pins  402 , ground plane pins  430 , and conductive grid ribs  202 , respectively, to pass through the entire thickness of the housing floor  304 . 
         [0062]      FIG. 14  is a first cross-sectional view of the GbX®-style backplane connector housing  300  along section V-V of  FIG. 12 . This view shows the lateral interior walls  343  of the lateral thru-hole slots  342  and the notched end wall  345  of the center trough  320 . 
         [0063]      FIG. 15  is a second cross-sectional view of the GbX®-style backplane connector housing  300  along section Z-Z of  FIG. 12 . This view shows details of the differential pins thru-hole slots  310 . Each slot  310  includes a tapered upper opening  350  that necks down to a smaller opening that exits at the bottom of the housing floor  304 . This slot configuration provides improved seating of the differential pins  402  when they are inserted into the slots  310 . 
         [0064]      FIGS. 16  A-B are perspective views of the twenty-rib conductive crosstalk reduction grid  200  included in the backplane connector  400  shown in  FIGS. 9-10 .  FIGS. 17-19  are certain further views of the crosstalk reduction grid  200 . 
         [0065]    The grid  200  includes a central spine  204  and twenty conductive ribs  202  extending perpendicularly from either side of the spine  204  in an opposing manner, forming ten rows of regularly spaced ribs. A central notch  212  defines a gap between the ribs  202  of each row, as well as the bottom of the spine  204 . The height, h, of the ribs  202  is about or equal to the thickness of the housing floor  304 . The length, l, of each rib  202  is typically sufficient to cover the horizontal width of two side-by-side differential pins  402 . 
         [0066]    One end  213  of the spine  204  terminates flush with an end pair of ribs. The other end  211  of the spine extends beyond the other end pair of ribs. 
         [0067]    A central trough  206  is formed in the top of the spine  204 . A plurality of thru-hole slots  208  are formed along the center of the trough  206  (see  FIGS. 16B and 17 ). The slots  208  and the trough are adapted to receive the ground plane shield  404  such that electrical contact is made between the grid  200  and the shield when the connector  400  is assembled. 
         [0068]    The grid  200  also includes means for frictionally engaging the connector housing  300  when it is inserted into the housing floor  304 . These means include bumps  210  protruding from the ends of each of the ribs  202  and bumps  214  protruding from the spine  204 . Slight protrusions can be formed elsewhere on the grid  200  to frictionally engage the housing  300 . Slight indentations can be formed in the housing openings and channels to receive the protrusions. The corresponding indentations permit the grid  200  to be snap-fitted into place within the housing floor  304 . 
         [0069]    The conductive grid  200  is preferably made of an injection-molded conductive polymer, but can also be made of any suitable electrically conductive material such as die cast or stamped metal, plated plastic or the like. 
         [0070]      FIG. 20  is a partial cross-sectional view of the GbX®-style backplane connector  400  along section Y-Y of  FIG. 10 . This view shows the non-conductive wall  433  formed in the housing floor  304  to separate the differential pins  402  from the ribs  202  of the conductive grid  201 . Detail  437  is a partial cut-away view of the wall  433 , which reveals the upper taper of the slots  310  and differential pin  402  seating within the slots  310 . 
         [0071]    The preceding detailed description has illustrated the principles of the invention using specific implementations of differential pair connectors. However, the invention is not limited to these particular implementations. For example, the inventive principles disclosed herein can be implemented in many other types of connectors, such as non GbX®-style connectors. It should be further understood that the connectors disclosed herein could be configured to contain any suitable number of differential pins and ground planes, or any suitably sized pin array, without departure from the principles of the invention. 
         [0072]    Therefore, while one or more specific embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments are possible that are within the scope of this invention. Further, the foregoing detailed description and drawings are considered as illustrative only of the principles of the invention. Since other modifications and changes may be or become apparent to those skilled in the art, the invention is not limited the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents are deemed to fall within the scope of the invention.