Abstract:
Interconnection assemblies which adjust their alignment and performance through the use of control feedback from the data transferred through the assemblies.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from, and hereby incorporates by reference, U.S. Provisional Application No. 60/557,128, filed Mar. 26, 2004 and entitled “Active Connectors.” 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of signal connection systems and the need for accurate and precise alignment of signal paths to ensure minimal signal loss and/or distortion. 
     BACKGROUND 
     Today&#39;s technique of building signal connection systems relies heavily upon methods and materials invented over forty years ago. Alignment pins, collars and pre-formed structures used in manufacturing define the tolerance of such connection systems. 
     For electrical signals, alignment of components comprising the signal path is required to achieve reliable conductivity.  FIG. 1  illustrates a prior art system containing IC packages, through-hole connectors and printed circuit boards (PCBs) wherein the alignment of the components is fixed at manufacturing time. 
     For optical signals, alignment of the optical signal conductors (typically fiber optic strands) is also critical to proper signal levels being launched into the signal carrying fiber. Additionally, with multiple wavelength transmitters and receivers being used in single fibers, separate light sources must be carefully arranged and aligned within the transmitter/receiver assemblies.  FIG. 2  illustrates a prior-art optical transceiver module wherein alignment is fixed once the module is assembled. In other optical modules micron level alignment of lasers and optical receivers is required during the manufacturing process. With such precision requirements, the cost of the equipment needed for manufacturing is high. On top of this, initial placement of components may shift over time (due to temperature, humidity, etc . . . ) thereby reducing the signal quality and strength. 
     With faster transistor switching speeds and with new, less disruptive signal path technologies, it is possible to transmit very high frequency signals over electrical signal paths. At higher frequencies, signal path stubs and varying impedances degrade the quality of the signal. The harmful effect of the stubs and variable impedance becomes more pronounced as the frequency increases. 
       FIG. 3  illustrates a prior art right angle connector wherein the alignment of the connector to the PCB is fixed at time of manufacture. In addition, the spatial relationship between the connector conductors is also fixed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
         FIG. 1  illustrates prior art connection system wherein the signal paths are fixed at time of manufacture; 
         FIG. 2  illustrates a prior art optical transceiver with multiple transmitters and receivers with a fixed mechanical alignment mechanism; 
         FIG. 3  illustrates a prior art through-hole connector with fixed alignment for mounting; 
         FIG. 4  illustrates a cross-section side view of a non-through-hole right-angle connector; 
         FIG. 5  illustrates a top view of the right-angle connector in  FIG. 4 ; 
         FIG. 6  illustrates an embodiment of the invention showing a cross-section side view of a right-angle connector utilizing actuators for signal path positioning; 
         FIG. 7  illustrates an embodiment of the invention showing a top view of a right-angle connector with actuators for signal path positioning in a different direction; 
         FIG. 8  illustrates an embodiment of the invention wherein the positioning of connector signal paths is controlled by the quality of the signals conducted through the connectors; 
         FIG. 9  illustrates an embodiment of the invention wherein the positioning of connector signal paths and packaging signal paths are controlled by the quality of the signals conducted through the connectors and packaging; and 
         FIG. 10  illustrates an embodiment of the invention wherein the alignment of optical pathways are controlled by the quality of the optical signal conducted through the pathways. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description and in the accompanying drawings, specific terminology and drawing symbols are set forth to provide a thorough understanding of the present invention. In some instances, the terminology and symbols may imply specific details that are not required to practice the invention. For example, the interconnection between circuit elements or circuit blocks may be shown or described as multi-conductor or single conductor signal lines. Each of the multi-conductor signal lines may alternatively be single-conductor signal lines, and each of the single-conductor signal lines may alternatively be multi-conductor signal lines. Signals and signaling paths shown or described as being single-ended may also be differential, and vice-versa. Signals and signal paths may be optical, electrical or mixtures of optical and electrical. For electrical signal, controlled impedance signal paths may be microstrip, stripline, coax, or any other suitable structure. For optical signals, signal paths may be fibers, prisms or other suitable structures. 
     In the following descriptions references are made to actuators. Actuators include devices which, through external stimulus, provide for positional displacement in one or more directions. The stimulus to the actuators is not limited to any one type and may include electrical, pneumatic, mechanical, optical or hydraulic methods. Actuators be adjusted once or multiple times. Actuators may have single control inputs or multiple control inputs. Actuators may require constant power consumption to achieve their displacement or may only require power to be consumed while the actuator is in the process of displacement. The active element for actuator motion may consist of, but is not limited to: motors, linear motors, stepper motors, piezoelectric transducers, dielectric elastomer polymers, electrostatic deflection, electromagnetic deflection, thermal deforming materials or combinations thereof. 
     In the following descriptions references are made to connectors. Connectors may be, but are not limited to right-angle, straight, surface mount, through-hole, array, mezzanine and sockets. Connectors also include assemblies. 
     In embodiments disclosed herein, assemblies contain signal paths wherein the position of the signal paths and/or the transmission characteristic of the signal paths are controlled by actuating structures of various types. Also, in a number of embodiments, signal path positions are adjusted based on data generated from the quality of the signal traveling through the assembly, thus providing closed loop control of signal transmission characteristics. Adjustments in signal path transmission characteristics may include, but are not limited to, adjustments to signal path impedance, signal path alignment, signal path spacing, signal path engagement, signal path disengagement, signal stub lengths, capacitance, inductance, and/or dielectric constant. 
       FIG. 4  illustrates an embodiment of a right-angle differential signal connector  10  which does not require through-hole technology to achieve connection between two PCBs  11 ,  24 .  FIG. 5  illustrates a different view of signal connector  10 . The traces on PCB  11  ( 15 ,  16 ,  17 ) are to connect to the traces on PCB  24  ( 21 ,  22 ,  23 ). The connector  10  employs electrical signal paths within its body  18 ,  19 ,  20  to make the connections. Signal path  20 - 12  in the connector  10  is utilized for ground and includes a conductive plane. Signal path  18 - 14  in the connector is used for ground and includes a conductive plane. Signal path  19 - 13  represents a strip-line transmission signal pair since the differential pair exists between two ground planes.  FIG. 5  illustrates a bottom view of the signal layers within the connector  10 . The impedance of the connector  10  is governed by the spacing of the differential pair traces  19 - 13  and the distance from each of the ground planes. 
     In one embodiment, the connector  10  is a differential connector intended to provide a constant differential impedance throughout its signal. For clarity in presenting this embodiment, an impedance of 100 Ohms is assumed although it may be a different value. Owing to manufacturing irregularities or positional tolerances, the signal traces  16  interfacing to the connector  10  from the PCB board  11  may have a differential impedance of 95 Ohms. Likewise, the impedance of the signal traces  22  on the PCB  24  may have a differential impedance of 105 Ohms. In this case, the entire signal path from PCB  11  to PCB  24  would have two impedance changes: from 95 Ohms to 100 Ohms as the signals entered from the PCB  11  and from 100 Ohms to 105 Ohms as the signal exited the connector  10  onto the other PCB  24 . Impedance mismatches add to signal distortion. 
       FIG. 6  illustrates an embodiment of the invention. The addition of actuators  55 ,  56 ,  57  to the connector  10  provides for adjustment of the position of the ground planes  20 - 12 ,  18 - 14  relative to the differential signal pair  19 - 13 . The actuators are connected to the ground planes through a mechanical coupling mechanism  58 ,  59 ,  60 . In the embodiment, the position of the mechanical coupling mechanism  58 , 59 , 60  is controlled through electrical circuits  61 ,  62 ,  63 . The ground planes  20 - 12 ,  18 - 14 , are thus able to be positioned closer/further away from the differential pair  19 - 13 . This movement adjusts the impedance of the differential signal pair. The invention allows for the actuators  55 ,  56 ,  57  to act independently or in unison. Therefore a gradient of positioning may be achieved providing a gradient in the impedance of the differential pair. It is this aspect of the invention which provides for linear impedance matching between two ends of an assembly. 
       FIG. 7  illustrates another embodiment of the invention where a signal conductor positioning actuator  75  has been added to a connector. The actuator  75  provides for alignment adjustment of the signal path conductors relative to the signal paths on the mating surfaces. With high-density connectors, due to tolerance build-ups, it is desirable to be able to adjust connector conductors so that they are centered upon their mating signal paths on the mating PCB. Differential pairs  74   a ,  74   b ,  74   c  are sandwiched between ground planes  70  and  71 . A non-conductive actuator arm  76  is attached  77  onto differential signal pairs  74   a ,  74   b ,  74   c  so that actuator movement translates into the differential signal pairs being adjusted from side-to-side. The signal paths may be made to pivot through the entire signal path construction or alternatively through a hinge point  78  in the path of the signal pairs. The actuator in this embodiment is controlled by electrical voltage through control wires  79 . While this embodiment illustrates the method for an actuator to control multiple signal path conductors, the invention does not restrict the number or position of signal path conductors. Signal path conductor without actuator control may be interspersed or interleaved with signal path conductors controlled by an actuator. Sets of signal path conductors may be controlled by one actuator with other sets under the control of a different actuator. 
     Although the embodiments of the invention illustrated in  FIG. 6  and  FIGS. 7  describe assemblies which provide for connections at right angles, the invention is not restricted to right angles and includes assemblies which provide for any angle of interconnection. 
       FIG. 8  illustrates an embodiment of the invention which includes connectors  81 ,  94  with actuator controlled signal path positioning and actuator controlled impedance as part of a chassis interconnect with a control system. The control system is comprised of data generators  87 ,  90  which provides reference signals  83 ,  84  for the adjustment of the active connectors  81 ,  94 . The reference signals are accepted by controllers  88 ,  89 . The controllers  88 ,  89  process the received reference signals  83 ,  84  and adjusts the positioning of the active elements of the connector  81 ,  94  through control lines  85 ,  86 . The criteria used by the controller for adjusting the signal path positioning in connectors  81 ,  94  may include, but is not limited to, a signal peak detect (for optimizing signal strength), a timing window detect, and/or a full spectral analysis (as provided in a DSP implementation) to optimize the positioning of the actuators within each of the connectors. The controller may apply the adjustment criteria once, during a power on sequence, or may apply the adjustment criteria continually or at a periodic rate. The frequency of adjustment is not restricted. Adjustments may also be made on demand, such as when errors occur. Although not shown, the invention provides for multiple actuators within a single assembly for adjusting multiple parameters (such as alignment, impedance, etc. . . . ). An alternate embodiment of the invention eliminates the need for generators  87 ,  90  and instead the controllers  88 ,  89  make the connector element adjustments based upon normal system signals traveling through the connectors by inspecting signal levels and timing from normal data exchanges. The package  91  may be, but is not limited to, integrated circuit packages, Multi-chip modules (MCMs), MEMS (Micro Electromechanical Systems), MOEMS (Micro OptoEletrical Mechanical Systems) or discrete components. 
       FIG. 9  illustrates an embodiment of the invention similar to  FIG. 8  but includes the addition of a positioning assembly  98  as part of a package  91  which provides for the alignment of incoming signal lines into package  91 . Similar to the line card connector  94 , the alignment (or other positioning parameters) are adjustable in the assembly  98  through the generator  87  and controller  89  mechanism. 
       FIG. 10  illustrates an embodiment of the invention wherein actuators are utilized to accurately adjust optical transceivers in relation to an optical channel  123 . In the case of multiple wavelength fiber optics, optical signals of different wavelength may be injected into a single optical channel (e.g. fiber). Owing to the critical tolerances necessary to place optical transceivers within micron precision, sophisticated manufacturing techniques are often needed. Instead of relying upon a mechanical placement of optical transceivers during manufacture, the embodiment shown in  FIG. 10  allows the rough placement of optical transceivers wherein the final adjustment is made by the system through the use of actuators. Optical transceiver  100  is attached to two actuators  101 ,  102  so that its alignment to the opening in a fiber  106  may be matched and optimized. The two alignment directions are shown with arrows  107 ,  108 . Other axis of control (eg rotation, tilt, etc . . . ) are anticipated but not illustrated. The control signals  104 ,  105  are generated by a controller which is based upon the signal being received by the optical transceivers  100 ,  114 ,  116 . 
     Although the invention has been described with reference to specific exemplary embodiments thereof, it will be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.