Abstract:
Electronic probes are provided. One such electronic probe includes: a housing configured to house electronic components; a coaxial cable connector configured to rotationally engage the housing, the coaxial cable connector having at least one inner surface that faces at least a portion of a first hole that extends through the coaxial cable connector, and having at least one outer surface; a coaxial cable having an inner conductor and an outer conductor, the outer conductor being attached to the at least one inner surface of the coaxial cable connector, and the inner conductor extending through the first hole in the coaxial cable connector. Methods and other systems are disclosed.

Description:
BACKGROUND 
     Many electronic probes (e.g., voltage or current probes) include a thin coaxial cable for carrying a signal to a measuring instrument. The thin coaxial cable is typically connected to an amplifier unit at one end, and to an interface (also known as a pod) for connecting to a measuring instrument. The thin coaxial cable is flexible and allows an electronic probe to be manipulated while maintaining a connection to a device being tested. One problem with using a thin coaxial cable is that it can be easily damaged. For example, external forces on the cable may cause its outer conductor to be dented. Such damage to the cable results in a high level of signal reflections, and thus limits the bandwidth capability of an electronic probe in which the cable is used. 
     One prior method of connecting a coaxial cable to an amplifier unit includes machining a cylindrical boss onto the amplifier unit. The coaxial cable is then cut to a precise length, and its coaxial braid is cut and spread over the cylindrical boss. A crimp sleeve is then slid over the coaxial braid, and a crimp die is used to crimp the cable in position. 
     Disadvantages of this prior method include: a weak physical connection between the coaxial cable and the amplifier unit, unacceptably high reflection losses at frequencies over 4 gigahertz (GHz), unacceptable deviations in inter-cable impedance from 50 ohms, difficulty in creating the connection, high variations in the quality of the connection, difficulty in disconnecting the cable when an electronic probe fails a quality test, and likely damage to the cable when disconnecting it from the amplifier unit. Based on the foregoing, it should be understood that there is a need for systems and methods that address these and/or other perceived shortcomings of the prior art. 
     SUMMARY 
     An embodiment of an electronic probe includes: a housing configured to house electronic components; a coaxial cable connector configured to rotationally engage the housing, the coaxial cable connector having at least one inner surface that faces at least a portion of a first hole that extends through the coaxial cable connector, and having at least one outer surface; a coaxial cable having an inner conductor and an outer conductor, the outer conductor being attached to the at least one inner surface of the coaxial cable connector, and the inner conductor extending through the first hole in the coaxial cable connector. 
     An embodiment of a method for manufacturing an electronic probe includes: attaching a coaxial cable having an inner conductor and an outer conductor to a connector that has at least one inner surface that faces at least a portion of a first hole that extends through the coaxial cable connector, and that has at least one outer surface, wherein the outer conductor is attached to the at least one inner surface of the coaxial cable connector, and the inner conductor extends through the first hole in the coaxial cable connector; and rotating the coaxial cable connector in order to attach the coaxial cable connector to a housing that houses electronic components. 
     Other systems, methods, features and/or advantages will be or may 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 systems, methods, features, and/or advantages be included within this description and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, like reference numerals designate corresponding parts throughout the several views. The components in the drawings are not necessarily drawn to scale 
         FIG. 1  is a block diagram depicting an embodiment of a measurement system. 
         FIG. 2  is a block diagram depicting an embodiment of selected components of an electronic probe. 
         FIGS. 3A and 3B  are schematic diagrams depicting an embodiment of a coaxial cable connector. 
         FIG. 4A  is a schematic diagram showing an embodiment of a coaxial cable connector that is connected to a cable assembly. 
         FIG. 4B  is a schematic diagram showing an embodiment of a coaxial cable connector that is connected to a coaxial cable. 
         FIG. 5  is schematic diagram depicting an embodiment of a coaxial cable connector that is being attached to an amplifier unit, according the invention. 
         FIG. 6  is a flow chart depicting an embodiment of a method for assembling an electronic probe. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a coaxial cable is attached to a coaxial cable connector such that an outer conductor of the coaxial cable maintains a constant inner diameter and remains coaxial with an inner conductor, without experiencing any distortions or discontinuities. This embodiment substantially reduces signal reflection at the region of contact between the outer conductor and the coaxial cable connector, and allows the coaxial cable to support applications involving frequencies over 20 GHz. Furthermore, the coaxial cable may be easily connected to and disconnected from another electronic probe component (e.g., an amplifier unit) without being damaged. 
       FIG. 1  is a block diagram depicting an embodiment of a measurement system  100 . The measurement system  100  includes an electronic probe  102  that is coupled to a measuring instrument  103  and to a device-under-test  101 . The device-under-test  101  may be, for example, an electronic device or circuit that is to be tested. The probe  102  is configured to provide the measuring instrument  103  with a probe signal that is responsive to one or more test signals received by the probe  102  from a device-under-test  101 . The probe  102  may be, for example, a voltage probe or a current probe. The measuring instrument  103  is configured to measure one or more characteristics of the probe signal received from the probe  102 . The measuring instrument  103  may be, for example, an oscilloscope, a spectrum analyzer, a logic analyzer, a vector analyzer, a network analyzer, or a time interval analyzer. 
       FIG. 2  is a block diagram depicting an embodiment of selected components of a probe  102 . The probe  102  includes a device-under-test (DUT) interface  201 , an amplifier unit  202 , a coaxial cable connector  203 , a coaxial cable  204 , and a measuring instrument interface  205 . The DUT interface  201  may include, for example, one or more wires, pins, or other conducting means that is/are configured to contact one or more respective probing points in a device-under-test  101 . The amplifier unit  202  is connected to the coaxial cable  204  via the coaxial cable connector  203 . The amplifier unit  202  houses electronic components that are configured to detect and/or amplify one or more test signals received via the DUT interface  201 . In an alternative embodiment, electronic components for detecting and/or amplifying a test signal may be housed in a plurality of respective units. 
     The coaxial cable  204  is preferably connected to the coaxial cable connector  203  by soldering a coaxial braid of the coaxial cable  204  to the coaxial cable connector  203 . The coaxial cable connector  203  is configured to rotationally engage the amplifier unit  202 . For example, a threaded portion of the coaxial cable connector  203  may be configured to engage a groove that is located in a cylindrical surface of the amplifier unit  202 . The coaxial cable  204  conducts a signal from the amplifier unit  202  to the measuring instrument  103  via the measuring instrument interface  205  (also known as a pod). The measuring instrument interface  205  is attached to the coaxial cable  204  and is configured to be connected to the measuring instrument  103 . 
       FIGS. 3A and 3B  are schematic diagrams depicting an embodiment of a connector  203 . The coaxial cable connector  203  includes a cable interface  301 , a rotation tool interface  302  and a threaded portion  303 . The cable interface  301  is preferably cylindrically shaped and is configured to be attached to the coaxial cable  204  (FIG.  2 ). For example, a coaxial braid within the coaxial cable  204  may be soldered to an interior surface of the cable interface  301 , as will be discussed in more detail below. The cable interface  301  may include a hole  406  for receiving solder material during the soldering process. The rotation tool interface  302  is configured to engage a rotation tool (e.g., a wrench) for rotating the coaxial cable connector  203 . The threaded portion  303  is configured to engage a groove that is located in a cylindrical surface of the amplifier unit  202 . A hole  304 , which is configured to receive a portion of the coaxial cable  204 , runs through the cable interface  301 , the rotation tool interface  302 , and the threaded portion  303 . 
       FIG. 4A  is a schematic diagram showing an embodiment of a connector  203  that is connected to a cable assembly  401 . The cable assembly  401  includes an outer jacket  402 , an outer conductor  403  (e.g., a coaxial braid), an inner conductor  404 , and wires  405 , among other components (not shown). The outer conductor  403  and the inner conductor  404  are part of a coaxial cable that extends through the cable assembly  401 . The cable assembly  401  is preferably attached to the coaxial cable connector  203  by soldering the outer conductor  403  to an interior surface of the cable interface  301 . Furthermore, a serve shield (not shown) that is part of the cable assembly  401  may be soldered to an exterior surface of the cable interface  301  in order to strengthen the physical connection between the cable assembly  401  and the coaxial cable connector  203 . The inner conductor  404  and the outer conductor  403  are configured to conduct a probe signal to the measuring instrument  103  (FIG.  1 ). The wires  405  are used for conducting power and/or control signals between the measuring instrument  103  and the amplifier unit  202  (FIG.  2 ). 
       FIG. 4B  is a schematic diagram depicting a coaxial cable  204  that is connected to a connector  203 . The coaxial cable  204  includes an inner conductor  404  and an insulation layer (dielectric)  407  that are inserted into a hole  304  ( FIGS. 3A and 3B ) that extends through the coaxial cable connector  203 . Furthermore, an outer conductor  403  of the coaxial cable  204  is inserted into a portion of the hole  304  that extends through the cable interface  301 , and is soldered to an interior wall of the cable interface  301 . Solder material may be introduced through the hole  406  during the soldering process. 
     Connecting the coaxial cable  204  to the coaxial cable connector  203  as shown in  FIG. 4B  allows the outer conductor  403  to maintain a constant inner diameter and to remain coaxial with the inner conductor  404  without experiencing any distortions or discontinuities. This can substantially reduce signal reflection at the region of contact between the outer conductor  403  and the coaxial cable connector  203 , and can allow the coaxial cable  204  to support applications involving frequencies over 20 GHz. Furthermore, the process of connecting the coaxial cable  204  to the coaxial cable connector  203  may be automated thereby increasing the quality of the connection while reducing cost. Once the coaxial cable  204  is connected to the coaxial cable connector  203 , the coaxial cable  204  may be easily connected to and disconnected from another electronic probe component (e.g., an amplifier unit  202  (FIG.  1 )) without damaging the coaxial cable  204 . The coaxial cable  204  is preferably, but not necessarily, part of the cable assembly  401  ( FIG. 4A ) that also includes wires  405  and an outer jacket  402  (FIG.  4 A), among other protective and/or insulating layers. 
       FIG. 5  is schematic diagram depicting an embodiment of a connector  203  that is in the process of being attached to an amplifier unit  202 . The amplifier unit  202  includes a side surface  500  having an opening  501  that is defined by an annular surface  502 . The coaxial cable connector  203  can be attached to the amplifier unit  202  by rotating the coaxial cable connector  203  such that the threaded portion  303  engages a groove  503  that is located in the cylindrical surface  502 . The side surface  500  also has openings  504  that are each configured to receive one or more of the wires  405  (FIG.  4 A). The threaded portion  303  can be indexed so that the wires  405  are properly positioned after the coaxial cable connector  203  is connected to the amplifier unit  202 . This eliminates the need to manipulate the wires  405  into position and therefore reduces the likelihood of damage to the coaxial cable  204  that may be caused by such manipulation. 
     Some of the advantages of connecting a coaxial cable  204  ( FIG. 4B ) to an amplifier unit  202  via a connector  203  as shown in  FIG. 5  can include:
         a) desirable electrical properties, such as low levels of signal reflection (e.g., less than 2%), that can be maintained at signal frequencies exceeding 20 GHz;   b) a physically strong connection;   c) a connection that can be easily made;   d) a connection and that is less costly to implement than prior approaches;   e) the coaxial cable  204  can be easily disconnected without being damaged; and/or   f) the coaxial cable  204  maintains an effective inter-cable impedance of 50 ohms.
 
Note, in some embodiments, few or none of the aforementioned advantages may be exhibited.
       

       FIG. 6  is a flow chart depicting an embodiment of a method  600  for assembling an electronic probe  102 . In step  601 , a coaxial cable  204  ( FIG. 2 ) is attached to a connector  203  (FIG.  2 ). The coaxial cable  204  is preferably attached to the coaxial cable connector  203  by soldering the outer conductor  403  of the coaxial cable  204  to an interior surface of the coaxial cable connector  203 . The coaxial cable connector  203  is then rotated to engage another electronic probe component, as indicated in step  602 . For example, the coaxial cable connector  203  can be connected to an amplifier unit  202  as illustrated in FIG.  5 . Once the coaxial cable connector is fully engaged with the other electronic probe component, the coaxial cable  204  may then conduct a probe signal to or from such component (depending on a desired implementation). If the coaxial cable  204  is suspected of being defective, then the coaxial cable connector  203  enables the coaxial cable  204  to be easily disconnected from the amplifier unit  202  without damaging the coaxial cable  204 . Once a coaxial cable  204  is disconnected from the amplifier unit  202 , then the coaxial cable  204  may be easily replaced with another coaxial cable using the method  600 . 
     It should be emphasized that the above-described embodiments are merely possible examples, among others, of the implementations. Many variations and modifications may be made to the above-described embodiments. All such modifications and variations are intended to be included herein within the scope of the disclosure and protected by the following claims.