Patent Publication Number: US-6911877-B2

Title: Coplanar waveguide launch package

Description:
BACKGROUND 
   The present invention relates generally to an electronic interconnect packaging technology. More specifically, the present invention relates to a coplanar waveguide launch package technology. 
   As illustrated in  FIG. 1  (in a perspective view), for various purposes such as testing and measurements, high frequency electronic signals carried on a coaxial transmission line  10  need to be coupled to a coplanar waveguide  20 . The transmission line  10  type is often referred to as “coaxial transmission line” or “coax” for short, and the signal is voltage on a center conductor wire  12  relative to an outer ground shield  13 . The coplanar waveguide  20  typically includes a signal trace  22  and ground traces  24  separated from the signal trace  22 , both fabricated on an insulating substrate  26 . 
   The coax  10  and the coplanar waveguide  20  are not connected directly. Rather, the signal coupling from the coax  10  to coplanar waveguide  20  is accomplished using a coplanar waveguide package  30  as illustrated in  FIGS. 2A and 2B . For frequencies above 10 GHz, as illustrated in  FIG. 2A  (in a perspective view), the coplanar waveguide package  30  is typically machined from its top-side to the mounting flanges  36  and from its bottom-side (or under-side) to the mounting flanges  36  resulting in a top-side cavity  32  and a bottom-side cavity  34 . The coplanar waveguide  20  is attached to the flanges  36 , in the bottom-side cavity  34 , to the coplanar waveguide package  30  with solder or conductive adhesive allowing the ground traces  24  to make electrical contact with the coplanar waveguide package  30 . 
   The coax  10  connects to the coplanar waveguide launch package  30  via a connector (not shown in the perspective drawing of FIG.  2 A. The signal is transferred from the center conductor wire  12  of  FIG. 1  to a pin  15  (illustrated in FIG.  2 B), the pin  15  terminating at a launch  38  and meeting the signal trace  22  at the launch  38 . The launch  38  generally refers to the area of the coplanar waveguide package  30  where the pin  15  contacts the signal trace  22 . The launch  38  is illustrated in more detail, in FIG.  2 B. The ground shield  13  of the coax  10  is electrically connected to the coplanar waveguide package, the pin  15  being insulated from the coplanar waveguide package  30 . Thus, the coplanar waveguide package  30  is the “ground” relative to the pin  15  and the signal trace  22  of the coplanar waveguide  20 . 
   In order to minimize signal reflections at the launch  38 , the pin  15  and the signal trace  22  need be precisely aligned in all three dimensions. For this reason, the top-side cavity  32  and the bottom-side cavity  34  must be machined very precisely relative to each other. This is difficult to achieve leading to relatively high cost of manufacture of the coplanar waveguide package  30 . Further, the removal of much material of the coplanar waveguide package  30  to create the bottom-side cavity  34  leaves little material to support mounting of components on the coplanar waveguide package  30 . Finally, the coplanar waveguide package  30  needs a bottom-lid (not shown) to enclose the bottom-side cavity  34  for environmental and electrical shielding of the bottom-side of the coplanar waveguide package  30 . The lid requirement adds to the cost of the manufacture of the coplanar waveguide package  30 . 
   Consequently, there remains a need for better coplanar techniques and devices to minimize power consumption while providing sufficient responses to users. 
   SUMMARY 
   The need is met by the present invention. In a first embodiment of the present invention, a signal transition device includes a first portion and a second portion connected to the first portion. The first portion is adapted to receive electrical signals, the signals transferred to a launch proximal to a first surface of the first portion. The second portion, connected to the first portion, has a support surface at a substantially normal angle relative to the first surface. The second portion is adapted to support a coplanar waveguide. 
   In a second embodiment of the present invention, a coplanar waveguide launch package includes a pin that terminates proximal to a first surface of the coplanar waveguide launch package and a support surface. The pin is adapted to carry electrical signals. The support surface at a substantially normal angle relative to the first surface. The support surface is adapted to support a coplanar waveguide. 
   In a third embodiment of the present invention, a microcircuit package includes a coplanar waveguide launch package. The coplanar waveguide launch package includes a first portion and a second portion connected to the first portion. The first portion is adapted to receive electrical signals, the signals transferred to a launch proximal to a first surface of the first portion. The second portion, connected to the first portion, has a support surface at a substantially normal angle relative to the first surface. The second portion is adapted to support a coplanar waveguide. 
   Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates coax transmission line and a coplanar waveguide; 
       FIGS. 2A and 2B  illustrate a prior art coplanar waveguide package with a coplanar waveguide; 
       FIG. 3A  illustrates a perspective view of one embodiment of a coplanar waveguide package of the present invention with a coplanar waveguide; 
       FIG. 3B  illustrates cutaway side view of the coplanar waveguide package illustrated in  FIG. 3A  cut along line A—A; 
       FIG. 3C  illustrates the coplanar waveguide package illustrated in  FIG. 3A  with a coplanar waveguide; 
       FIG. 3D  illustrates a portion of the coplanar waveguide package illustrated in  FIG. 3C  with a coplanar waveguide cutaway side view, the portion illustrated in more detail; and 
       FIG. 4  illustrates a microcircuit package including the coplanar waveguide package illustrated in FIG.  3 A. 
   

   DETAILED DESCRIPTION 
   As shown in the figures for the purposes of illustration, one embodiment of the present invention is exemplified by a coplanar waveguide launch package having a first portion and a second portion. The first portion is adapted to receive electrical signals from a conductive wire. The received signals terminate proximal to a launch at a first surface of the first portion. The second portion, connected to the first portion, has a support surface forming a junction with the first surface at a substantially normal angle. The support surface of the second portion is adapted to support a coplanar waveguide. 
   Because the coplanar waveguide launch package of the present invention does not require removing of bottom portions of the coplanar waveguide launch package, it overcomes the shortcoming of the coplanar waveguide launch packages having prior art designs. In particular, unlike a coplanar waveguide launch package of the prior art design, the coplanar waveguide launch package of the present invention does not require machining of the bottom-side, does not require removal of the bottom-side material, and does not require a bottom lid. 
   Using the coplanar waveguide launch package of the present invention, signals carried on a coaxial transmission line can be transitioned to a coplanar waveguide. For this reason, the coplanar waveguide launch package of the present invention is also referred to as a signal transition device. 
     FIG. 3A  illustrates a perspective view of one embodiment of the coplanar waveguide launch package  40  of the present invention.  FIG. 3B  illustrates a cutaway side view of the coplanar waveguide launch package  40  cut along line A—A shown in FIG.  3 A.  FIG. 3C  illustrates the same perspective view of the coplanar waveguide launch package  40  but including a coplanar waveguide  56 .  FIG. 3D  illustrates launch portion  42  of the coplanar waveguide launch package  40  with a coplanar waveguide  56 . 
   Referring to  FIGS. 3A through 3D , the coplanar waveguide launch package  40  includes a first portion  44  and a second portion  46 . The first portion  44  is adapted to receive electrical signals from, for example, a coax  10 . The coax  10  having similar configuration as the coax  10  illustrated in FIG.  1  and discussed above. A connector  43  can be used as a transition means to transfer the signals from the center conductor wire  13  (illustrated in  FIG. 1 ) to a pin  48  of the first portion  44 . The pin  48  terminates at the launch  42  transferring the signals to the launch  42  at a first surface  50  of the first portion  44 . The launch  42  refers to generally portions of the coplanar waveguide package  40  where the pin  48  connects with a signal trace  54  of a coplanar waveguide  56  thereby allowing the signals to be launched onto the coplanar waveguide  56 .  FIG. 3D  illustrates the launch  42  in greater detail. The first surface  50  defines a vertical cut-out relief  53 . 
   The second portion  46  is connected to the first portion  44 . The second portion  46  has a support surface  58  that meets the first surface  50  at a substantially normal angle thereby forming a junction  57  with the first surface  50 . That is, the support surface  58  meets the first surface  50  at a perpendicular angle forming the junction  57 . The meeting of the two surfaces  50  and  58  defines a line  57 . The support surface  58  is adapted to support a coplanar waveguide  56  as illustrated in FIG.  3 C. 
   A part of the first portion  44  is undercut forming an overhanging ledge proximal to the junction between the first surface  50  and the support surface  58 . The part of the first portion  44  effected by the undercut thus creating the overhanging ledge is generally indicated by reference numeral  62 . The reference numeral  62  is used herein this document to referred to the undercut, the overhang, and the overhanging ledge. When the coplanar waveguide  56  is placed on the support surface  58  as illustrated in  FIG. 3C , a portion of the coplanar waveguide  56  is received under the overhanging ledge  62  providing stability of the coplanar waveguide  56  as well as creating electrical contacts between the coplanar waveguide  56  and the coplanar waveguide launch package  40 . In particular, when the coplanar waveguide  56  is placed on the support surface  58 , the signal trace  54  of the coplanar waveguide  56  is positioned proximal to the pin  48 . Further, ground traces  55  of the coplanar waveguide  56  make contact with the first portion  44  of the coplanar waveguide launch package  40 . 
   The depth  60  of the undercut  62  is substantially greater than or equal to the thickness of the coplanar waveguide  56  which can be, for example, a fraction of a millimeter. The width  61  of the undercut  62  is substantially equal to the depth of the vertical cut-out relief  53  which can be, for example a fraction of a millimeter. The exact size depends on the frequency range, substrate thickness, mechanical mounting, and other considerations. The support surface  58  defines a bottom side gap  59 . The space defined by the bottom side gap  59  can be utilized by a T-slot cutter bit to mill the undercut  62 . As illustrated in the Figures, the coplanar waveguide launch package  40  including the first portion  44  and the second portion  46  is machined from a single block of material. In fact, the coplanar waveguide launch package  40  can be a part of a larger microcircuit package  70  as illustrated in FIG.  4 . Referring to  FIG. 4 , the microcircuit package  70  can include additional components in addition to the coplanar waveguide launch package  40 . Further, the microcircuit package  70  can be formed from a single block of material. 
   Because the coplanar waveguide launch package  40  of  FIGS. 3A through 4  of the present invention does not require removing of bottom portions, it overcomes the shortcoming of the coplanar waveguide launch packages having prior art designs. In particular, unlike a coplanar waveguide launch package  30  (of  FIGS. 2A and 2B ) of the prior art design, the coplanar waveguide launch package  40  (of  FIGS. 3A through 4 ) of the present invention does not require machining of the bottom-side, does not require removal of the bottom-side material, and does not require a bottom lid. 
   From the foregoing, it will be apparent that the device of the present invention is novel and offers advantages over the current art. Although a specific embodiment of the invention is described and illustrated above, the invention is not to be limited to the specific forms or arrangements of parts so described and illustrated. The invention is limited only by the claims.