Abstract:
A connector assembly that integrates an optical fiber connector with a fiber optic transceiver into one assembly. The optical fiber connector is provided with end float for optical connection to an optical back panel. Some components of the fiber optic transceiver are mounted on the optical fiber connector and float with the connector. Other components of the fiber optic transceiver are mounted in static positions on a circuit card assembly that is part of the connector assembly. A flexible circuit electrically connects the transceiver components mounted on the optical fiber connector with the static transceiver components. The connector assembly eliminates the use of a fiber pigtail, improves the ease of mounting and removal of the fiber optic transceiver from the host board, consolidates the transceiver circuitry into one assembly, and allows reduction of the host board footprint and/or provides additional space on the host board for mounting other components.

Description:
FIELD 
     This disclosure relates to a connector assembly having an integrated fiber optic transceiver. 
     BACKGROUND 
     A known fiber optic transceiver construction is illustrated in  FIGS. 1 and 2 . This known construction includes a transceiver assembly  2  with multiple circuits  4   a ,  4   b  for performing the optical transmit and receive functions. The circuits are mounted on a substrate  6  and the assembly  2  is electrically connected to a host board via a leadframe  8 . A fiber pigtail  10  is permanently attached to the assembly  2  at one end, with the other end of the fiber pigtail  10  connected to an optical fiber connector  12 , such as a mechanical transfer (MT) connector, for connection to an optical back panel. 
     Because of the presence of the fiber pigtail, the leadframe  8  is typically hand soldered onto the host board rather than using an automated process, which is labor intensive. Further, the host circuit board is sometimes reworked or repaired during which the transceiver assembly  2  is removed and replaced which is made difficult due to the hand soldering. Oftentimes, the fiber pigtail  10  is damaged or destroyed during the repair or rework process since the pigtail is exposed. Further, the transceiver assembly on the host board occupies space on the board that could be eliminated or used to mount other components. 
     SUMMARY 
     A connector assembly having an integrated fiber optic transceiver is described that eliminates the use of a fiber pigtail, improves the ease of mounting and removal of the transceiver from the host board, consolidates the transceiver circuitry into one assembly, and allows reduction of the host board footprint and/or provides additional space on the host board for mounting other components. 
     The connector assembly integrates an optical fiber connector with a fiber optic transceiver into one assembly. The optical fiber connector is provided with end float for optical connection to an optical back panel. Some components of the transceiver are mounted on the optical fiber connector and float with the connector. Other components of the transceiver are mounted in static positions on a circuit card assembly that is part of the connector assembly. A flexible circuit electrically connects the transceiver components mounted on the optical fiber connector with the static transceiver components. 
     In one example, the connector assembly includes a housing and an optical fiber connector at least partially disposed in the housing. The optical fiber connector has first and second ends, and the first and second ends are each capable of making optical interconnection (i.e. the optical fiber connector is of uniferrule design). In addition, the optical fiber connector is mounted to allow it to float relative to the housing. A fiber optic transceiver component is mounted to the second end of the optical fiber connector so that it floats with the optical fiber connector. A circuit card assembly is mounted in the housing, and includes mounted thereon transceiver electronics associated with the transceiver component. A flexible circuit is provided that has a first end connected to the optical fiber connector and a second end connected to the circuit card assembly. 
    
    
     
       DRAWINGS 
         FIG. 1  illustrates a conventional fiber optic transceiver construction that utilizes a fiber pigtail. 
         FIG. 2  is a cross-sectional view of the transceiver assembly shown in  FIG. 1 . 
         FIG. 3  is a perspective view of an exemplary connector assembly described herein. 
         FIG. 4  is an exploded view of various components of the connector assembly of  FIG. 3 . 
         FIG. 5  is perspective view of the connector assembly of  FIG. 3  with the housing removed. 
         FIG. 6  shows a plurality of the connector assemblies of  FIG. 3  mounted on a host board. 
         FIG. 7  shows a plurality of the fiber optic transceiver constructions of  FIG. 1  mounted on a host board. 
     
    
    
     DETAILED DESCRIPTION 
     An example of a connector assembly  20  will now be described with reference now to  FIGS. 3-5 . The assembly  20  includes a housing  22 , an optical fiber connector  24 , an integrated fiber optic transceiver, and an electrical input/output (I/O) connector  26  mounted on the housing and configured for connection to a host circuit board  28  (shown in  FIG. 6 ). 
     The housing  22 , which is best seen in  FIGS. 3 and 4 , includes a housing body  30  made of plastic or other suitable material. The housing body  30  includes a central box section  32 , an overhanging ledge portion  34  joined to the box section and extending from an end of the box section, and a canopy section  36  joined to the box section and extending from an opposite end of the box section. 
     The box section  32  is a rectangular structure with a bottom wall  38 , side walls  40 ,  42 , a back wall  44  and a front wall  46 . The top edge of the back wall  44  forms a continuation of a ledge  48  that is defined on the side walls  40 ,  42 . 
     The ledge portion  34  includes side walls  50 ,  52  and a back wall  54  that are shorter in height than the side walls  40 ,  42  of the box section  32 . The side walls  50 ,  52  extend from the top of the side walls  40 ,  42  so that the ledge portion  34  overhangs or is cantilevered over space beneath it. In addition, flanges  56  are formed on the bottom of the side walls  50 ,  52 , the back wall  54  and on the ledge portion facing side of the back wall  44 , with an opening  58  being defined by the flanges  56 . 
     The canopy section  36  includes side walls  60 ,  62  and a top wall  64  that extend from the front wall  46  and define an inverted channel  66 . The canopy section  36  also includes a partial bottom wall  68  that closes off a portion of the channel  66 . The channel  66  communicates with the interior of the box section  32  via an opening (not shown) formed in the wall  46 . 
     The housing  22  also includes a removable cover  69  that is supported on the top edges of the box section and the ledge portion for closing off the top of the box section  32  and the top of the ledge portion  34 . 
     The optical fiber connector  24  is mounted on the housing with the connector  24  disposed in the channel  66 , with the first end  70  of the connector  24  extending past the canopy section  36  so that the end  70  is accessible for connection to a mating connector on an optical back panel. The second end  72  of the connector  24  is disposed within the box section  32 . The connector  24  is a uniferrule, with each end  70 ,  72  being configured for optical interconnection. Any optical fiber connector of uniferrule construction can be used. 
     One example of a suitable uniferrule is described in U.S. patent application Ser. No. 12/467,398, filed on May 18, 2009, entitled “Optical Fiber Connector and Method” which is incorporated herein by reference. As described in that application, and illustrated herein in  FIG. 4 , an optical fiber connector is formed by using two commercially available, off-the-shelf optical fiber connector members  80 . Each connector member  80  has a first end (corresponding to the ends  70 ,  72 ) with a first, low eccentricity tolerance and a second end with a second eccentricity tolerance that is greater than the first eccentricity tolerance. As shown in  FIGS. 4 and 5 , the two connector members are then connected together back-to-back, so that the second ends face each other and the first ends are disposed at opposite ends of the resulting connector forming the ends  70 ,  72 . The resulting connector is a uniferrule design that has low eccentricity tolerance at each end, with each end being configured for optical interconnection with improved light transmission. Alignment pins  82  extend through through-holes in the connector members  80  to join the connector members together. 
     Other uniferrule constructions could be used for the connector  24 , such as the US Conec uniferrule available from US Conec Ltd. of Hickory, N.C. 
     The connector  24  is mounted to permit it to float, i.e. move, longitudinally within the channel  66  as indicated by the arrows in  FIG. 3 . The amount of float provided can be, for example, about 0.10 inch. 
     With reference to  FIGS. 4 and 5 , a circuit card assembly  100  is mounted in the housing  22 , with an end of the assembly  100  supported on the ledge  48 . The circuit card assembly  100  has mounted thereon a number of electronic components for operation of a fiber optic transceiver that is integrated into the assembly  20 , and other electronic components. For example, transceiver electronics associated with the integrated fiber optic transceiver, such as a transimpedance amplifier  102  and a vertical cavity surface emitting laser (VCSEL) driver  104 , can be mounted on the circuit card assembly  100 . Other electronic components such as memory and a microcontroller can also be mounted on the assembly  100 . 
     The electronic components  102 ,  104 , are mounted so that they are positioned adjacent the top of the housing  22  which facilitates efforts to remove heat from any high heat generating components. 
     In addition to transceiver electronics, the integrated fiber optic transceiver also includes an optical receiver  110 , for example a pin diode array (PDA), and a transmitter  112 , for example a VSCEL array. The receiver  110  and transmitter  112  are mounted on a mounting block  114  that is disposed at the front end  72  of the connector  24 . The mounting block  114  is provided with alignment pin through-holes  116  through which the alignment pins  82  extend when assembled to secure the block  114  to the connector  24 . Therefore, the block  114 , and the receiver and transmitter mounted thereon, float with (i.e. are movable with) the connector  24 . 
     Electrical connection between the receiver  110  and the transmitter  112  on the block  114 , and the transceiver electronics on the circuit card assembly  110 , is provided by a flexible electrical circuit  118 , for example a high density interconnect (HDI) flex. 
     The flex circuit  118  has a first end  120  connected to the optical fiber connector  24  by being disposed between the end  72  and the block  114 . A pair of alignment pin through-holes  122  are formed in the first end  120  through which the alignment pins  82  extend to secure the connector  118  to the optical fiber connector  24 . A second end  124  of the connector  118  is connected to bottom surface of the circuit card assembly  100 . 
     The first end  120  of the flex circuit  118  connects to the receiver  110  and the transmitter  112  for directing electrical signals to and from the receiver and transmitter. Likewise, the second end  124  of the flex circuit  118  connects to the transceiver electronics  102 ,  104  on the circuit card assembly for directing electrical signals to and from the electronics  102 ,  104  and other electronic components on the circuit card assembly. 
     A spring keeper  130  that is sized for disposition in the box section  32  is located in front of the block  114 . The spring keeper  130  includes a spring blind-hole  132  that receives an end of a coil spring  134 . The other end of the spring  134  abuts against the wall  44 . The spring keeper  130  also includes a pair of alignment pin blind-holes  136  (i.e. on the side facing the block  114 ) that when assembled receive the ends of the alignment pins  82  to secure the spring keeper  130  to the connector  24 , the block  114  and the end  120  of the flex circuit  118 . 
     It should be evident from the above description that the connector  24 , the end  120  of the flex circuit  118 , the block  114  supporting the optical receiver and transmitter, and the spring keeper  130  are secured together and can float. The spring  134  applies a bias force to these dynamic members, biasing the connector  24  and the members connected thereto back to a home position. As shown in  FIG. 3 , stops  140  are formed that interact with the wider, facing ends of the connector members  80  to limit the travel of the connector  24 . 
     The electrical input/output (I/O) connector  26  is mounted on the bottom side of the circuit card assembly in the overhanging ledge portion  34  and projects through or is otherwise accessible through the opening  58  for connection with a suitably configured mating connector. Any type of electrical I/O connector can be used. In the illustrated example, the connector  26  includes a pin connector  142  that is connected to the circuit card assembly, which is intended to mate with a mating connector on the host board  28  ( FIG. 6 ). The connector  26  is accessible through the downward facing opening  58  in the ledge portion  34 , with a plurality of connector elements thereof facing downward. 
     With reference to  FIG. 6 , three assemblies  20  are shown arranged side-by-side on the host circuit board  28 . Because the fiber optic transceiver is integrated into the assembly, room is freed up on the board  28 , allowing a reduction in the board size and/or freeing space for mounting additional electronic components. The assemblies  20  are connectable to an optical back panel via the end  70  of the optical fiber connector  24  that extends from the housing  22 . Further, only the ledge portion  34  of the housing  22  extends over the surface of the board  28 , allowing electrical interconnection to the board  28 . 
     In contrast, with reference to  FIGS. 1 and 7 , the conventional transceiver assemblies  2  mount directly on a host board  150 , with fiber pigtails (shown in  FIG. 1 ) running from the assemblies  2  to the optical fiber connectors  12 . The assemblies  2  take up space on the board  150 . Further, the presence of the fiber pigtails creates problems when installing the assemblies, and for maintenance of the board  150 . 
     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.