Abstract:
A fixture for radio frequency (“RF”) testing of an assembled wireless device, the wireless device having a removable casing concealing one or more RF spring connectors, the fixture comprising: a retainer for receiving the wireless device with the removable casing removed; a coaxial connector mounted through the retainer, the coaxial connector having a center contact and a shield contact, the coaxial connector for communicating RF test signals through a coaxial cable with external test equipment; a circuit board mounted on an inner side of the retainer and having one or more pads each for receiving one of the center and shield contacts; and, one or more probes mounted on ones of the pads for contacting ones of the RF spring connectors to distribute the RF test signals.

Description:
[0001]     This application claims priority from U.S. Provisional Patent Application No. 60/617,657, filed Oct. 13, 2004, and incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to the field of wireless device radio frequency (“RF”) testing, and more specifically, to a fixture for RF testing of wireless devices having an adapter for matching RF spring connectors to a coaxial connector (e.g., sub-miniature version A (“SMA”)).  
       BACKGROUND  
       [0003]     Current wireless mobile communication devices include microprocessors, information storage capability, and run one or more software applications. Examples of software applications used in these wireless devices include micro-browsers, address books, and email clients. Additionally, these generations of wireless devices have access to a plurality of services via the Internet. A wireless device may, for example, be used to browse web sites on the Internet, to transmit and receive graphics, and to execute streaming audio and/or video applications.  
         [0004]     Wireless devices are typically fully tested before being shipped from a manufacturer&#39;s factory. This is especially important for the newer generations of wireless devices which have increased functionality as described above.  
         [0005]     Once a wireless device is assembled in full plastics, it typically progresses through various test stages to qualify each of its components. For mobile cellular devices these tests may include the following: RF, keys, internal microphone, internal speaker, charger, buzzer, vibrator, display, etc.  
         [0006]     With respect to RF testing, many wireless devices do not have an industry standard RF connector for connection to test equipment. Rather, these wireless devices may have a set of simple spring contacts. In addition, to connect such devices to test equipment typically requires the use of bulky external fixturing (e.g., “bulls-eye”) that may not only hinder the portability of the device under test (“DUT”) but may also require the partial disassembly of the DUT which in turn may compromise the integrity of the DUT.  
         [0007]     A need therefore exists for a method and system for the efficient RF testing of assembled wireless devices. Accordingly, a solution that addresses, at least in part, the above and other shortcomings is desired.  
       SUMMARY  
       [0008]     According to one aspect of the invention, there is provided a fixture for radio frequency (“RF”) testing of an assembled wireless device, the wireless device having a removable casing concealing one or more RF spring connectors, the fixture comprising: a retainer for receiving the wireless device with the removable casing removed; a coaxial connector mounted through the retainer, the coaxial connector having a center contact and a shield contact, the coaxial connector for communicating RF test signals through a coaxial cable with external test equipment; a circuit board mounted on an inner side of the retainer and having one or more pads each for receiving one of the center and shield contacts; and, one or more probes mounted on ones of the pads for contacting ones of the RF spring connectors to distribute the RF test signals.  
         [0009]     Preferably, the pads for receiving the shield contact are distributed around the pads for receiving the center contact to thereby match the impedance of the coaxial connector.  
         [0010]     Preferably, the one or more probes are mounted on the pads for receiving the shield contact.  
         [0011]     Preferably, the coaxial connector includes a 50 ohm coaxial connector.  
         [0012]     Preferably, the coaxial connector includes a sub-miniature-A (“SMA”) connector.  
         [0013]     Preferably, the coaxial connector is a jack connector.  
         [0014]     Preferably, the probes have spring-mounted tips for contacting the RF spring connectors.  
         [0015]     Preferably, the fixture further includes a spacer for spacing the circuit board between the inner side of the retainer and the RF spring connectors.  
         [0016]     Preferably, the spacer is a polycarbonate spacer.  
         [0017]     Preferably, the RF testing includes temperature testing.  
         [0018]     Preferably, the retainer has one or more clips for securely coupling the retainer to the wireless device.  
         [0019]     Preferably, the RF testing includes environmental testing.  
         [0020]     Preferably, the retainer is moulded for hand-gripping by a user.  
         [0021]     Preferably, the retainer is moulded for attachment to an arm assembly of the external test equipment for manipulating the wireless device during the RF testing.  
         [0022]     Preferably, the wireless device includes memory for storing an interactive test application for directing the wireless device in response to the RF test signals.  
         [0023]     According to another aspect of the invention, there is provided a method for radio frequency (“RF”) testing of an assembled wireless device, the wireless device having a removable casing concealing one or more RF spring connectors, the method comprising: providing a fixture having: a retainer for receiving the wireless device with the removable casing removed; a coaxial connector mounted through the retainer, the coaxial connector having a center contact and a shield contact, the coaxial connector for communicating RF test signals through a coaxial cable with external test equipment; a circuit board mounted on an inner side of the retainer and having one or more pads each for receiving one of the center and shield contacts; and, one or more probes mounted on ones of the pads for contacting ones of the RF spring connectors to distribute the RF test signals; and, applying the RF test signals to the coaxial connector.  
         [0024]     According to another aspect of the invention, there is provided a system for radio frequency (“RF”) testing of an assembled wireless device, the wireless device having a removable casing concealing one or more RF spring connectors, the system comprising: a fixture having: a retainer for receiving the wireless device with the removable casing removed; a coaxial connector mounted through the retainer, the coaxial connector having a center contact and a shield contact, the coaxial connector for communicating RF test signals; a circuit board mounted on an inner side of the retainer and having one or more pads each for receiving one of the center and shield contacts; and, one or more probes mounted on ones of the pads for contacting ones of the RF spring connectors to distribute the RF test signals; and, test equipment coupled to the coaxial connector through a coaxial cable for communicating the RF test signals. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]     Further features and advantages of the embodiments of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:  
         [0026]      FIG. 1  is a block diagram illustrating an exemplary wireless device adapted in accordance with an embodiment of the invention;  
         [0027]      FIG. 2  is a block diagram illustrating a memory of the wireless device of  FIG. 1 . in accordance with an embodiment of the invention;  
         [0028]      FIG. 3  is a front view illustrating the wireless device of  FIG. 1  in accordance with an embodiment of the invention;  
         [0029]      FIG. 4  is a perspective view illustrating an exterior of an RF test fixture for an assembled wireless device in accordance with an embodiment of the invention;  
         [0030]      FIG. 5  is a perspective view illustrating an interior of the RF test fixture in accordance with an embodiment of the invention;  
         [0031]      FIG. 6  is a partial cross-sectional view of the RF test fixture along line A-A of  FIG. 5 ;  
         [0032]      FIG. 7  is a top view of the RF test fixture of  FIG. 6 ;  
         [0033]      FIG. 8  is a back side view of the RF test fixture of  FIG. 6 ; and,  
         [0034]      FIG. 9  is a left side detail view of the RF test fixture of  FIG. 6 .  
     
    
       [0035]     It will be noted that throughout the appended drawings, like features are identified by like reference numerals.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]      FIG. 1  is a block diagram illustrating an exemplary wireless device  102  adapted in accordance with an embodiment of the invention. Wireless device  102  is a two-way communication device having at least voice and advanced data communication capabilities, including the capability to communicate with other computer systems. Depending on the functionality provided by device  102 , it may be referred to as a data messaging device, a two-way pager, a cellular telephone with data messaging capabilities, a wireless Internet appliance, or a data communication device (with or without telephony capabilities). Device  102  may communicate with any one of a plurality of fixed transceiver stations  100  within its geographic coverage area.  
         [0037]     Device  102  will normally incorporate a communication subsystem  111 , which includes a RF receiver, a RF transmitter, and associated components, such as one or more (preferably embedded or internal) antenna elements and, local oscillators (“LOs”), and a processing module such as a digital signal processor (“DSP”) (all not shown). As will be apparent to those skilled in field of communications, particular design of communication subsystem  111  depends on the communication network in which device  102  is intended to operate.  
         [0038]     Network access is associated with a subscriber or user of device  102  and therefore device  102  requires a Subscriber Identity Module (or “SIM” card)  162  to be inserted in a SIM IF  164  in order to operate in the network. Device  102  is a battery-powered device so it also includes a battery IF  154  for receiving one or more rechargeable batteries  156 . Such a battery  156  provides electrical power to most if not all electrical circuitry in device  102 , and battery IF  154  provides for a mechanical and electrical connection for it. The battery IF  154  is coupled to a regulator (not shown) which provides power V+ to all of the circuitry.  
         [0039]     Device  102  includes a microprocessor  138  which controls overall operation of device  102 . Communication functions, including at least data and voice communications, are performed through communication subsystem  111 . Microprocessor  138  also interacts with additional device subsystems such as a display  122 , a flash memory  124  or other persistent store, a random access memory (“RAM”)  126 , auxiliary input/output (“I/O”) subsystems  128 , a serial port  130 , a keyboard  132 , a speaker  134 , a microphone  136 , a short-range communications subsystem  140 , and any other device subsystems generally designated at  142 . Some of the subsystems shown in  FIG. 1  perform communication-related functions, whereas other subsystems may provide “resident” or on-device functions. Notably, some subsystems, such as keyboard  132  and display  122 , for example, may be used for both communication-related functions, such as entering a text message for transmission over a communication network, and device-resident functions such as a calculator or task list. Operating system software used by microprocessor  138  is preferably stored in a persistent store such as flash memory  124 , which may alternatively be a read-only memory (“ROM”) or similar storage element (not shown). Those skilled in the art will appreciate that the operating system, specific device applications, or parts thereof, may be temporarily loaded into a volatile store such as RAM  126 .  
         [0040]     Microprocessor  138 , in addition to its operating system functions, preferably enables execution of software applications on device  102 . A predetermined set of applications which control basic device operations, including at least data and voice communication applications, will normally be installed on device  102  during its manufacture. A preferred application that may be loaded onto device  102  may be a personal information manager (“PIM”) application having the ability to organize and manage data items relating to the user such as, but not limited to, instant messaging (“IM”), e-mail, calendar events, voice mails, appointments, and task items. Naturally, one or more memory stores are available on device  102  and SIM  162  to facilitate storage of PIM data items and other information.  
         [0041]     The PIM application preferably has the ability to send and receive data items via the wireless network. In a preferred embodiment, PIM data items are seamlessly integrated, synchronized, and updated via the wireless network, with the mobile station user&#39;s corresponding data items stored and/or associated with a host computer system thereby creating a mirrored host computer on device  102  with respect to such items. This is especially advantageous where the host computer system is the mobile station user&#39;s office computer system. Additional applications may also be loaded onto device  102  through network  100 , an auxiliary I/O subsystem  128 , serial port  130 , short-range communications subsystem  140 , or any other suitable subsystem  142 , and installed by a user in RAM  126  or preferably a non-volatile store (not shown) for execution by microprocessor  138 . Such flexibility in application installation increases the functionality of device  102  and may provide enhanced on-device functions, communication-related functions, or both. For example, secure communication applications may enable electronic commerce functions and other such financial transactions to be performed using device  102 .  
         [0042]     In a data communication mode, a received signal such as a text message, an e-mail message, or web page download will be processed by communication subsystem  111  and input to microprocessor  138 . Microprocessor  138  will preferably further process the signal for output to display  122  and/or to auxiliary I/O device  128 . A user of device  102  may also compose data items, such as e-mail messages, for example, using keyboard  132  in conjunction with display  122  and possibly auxiliary I/O device  128 . Keyboard  132  is preferably a complete alphanumeric keyboard and/or telephone-type keypad. These composed items may be transmitted over a communication network through communication subsystem  111  or short range communication subsystem  140 .  
         [0043]     For voice communications, the overall operation of device  102  is substantially similar, except that the received signals would be output to speaker  134  and signals for transmission would be generated by microphone  136 . Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on device  102 . Although voice or audio signal output is preferably accomplished primarily through speaker  134 , display  122  may also be used to provide an indication of the identity of a calling party, duration of a voice call, or other voice call related information, as some examples.  
         [0044]     Serial port  130  in  FIG. 1  is normally implemented in a personal digital assistant (“PDA”)-type communication device for which synchronization with a user&#39;s desktop computer is a desirable, albeit optional, component. Serial port  130  enables a user to set preferences through an external device or software application and extends the capabilities of device  102  by providing for information or software downloads to device  102  other than through a wireless communication network. The alternate download path may, for example, be used to load an encryption key onto device  102  through a direct and thus reliable and trusted connection to thereby provide secure device communication.  
         [0045]     Short-range communications subsystem  140  of  FIG. 1  is an additional optional component which provides for communication between device  102  and different systems or devices, which need not necessarily be similar devices. For example, subsystem  140  may include an infrared device and associated circuits and components, or a Bluetooth™ communication module to provide for communication with similarly-enabled systems and devices. Bluetooth™ is a registered trademark of Bluetooth SIG, Inc.  
         [0046]      FIG. 2  is a block diagram illustrating a memory  200  of device  102 , in accordance with an embodiment of the invention, showing various software components for controlling device  102 . Memory  200  may be flash memory  124 , RAM  126  or a ROM (not shown), for example. In accordance with an embodiment of the invention, device  102  is intended to be a multi-tasking wireless communications device configured for sending and receiving data items and for making and receiving voice calls. To provide a user-friendly environment to control the operation of device  102 , an operating system (“O/S”)  202  resident on device  102  provides a basic set of operations for supporting various applications typically operable through a graphical user interface (“GUI”)  204 . For example, O/S  202  provides basic input/output system features to obtain input from Auxiliary I/O  108 , keyboard  132  and the like and for facilitating output to the user. In accordance with an embodiment of the invention, there is provided an interactive test application  206  for RF testing of the assembled device  102  such as during a RF test phase stage of a production line test system. Though not shown, one or more applications for managing communications or providing personal digital assistant like functions may also be included.  
         [0047]      FIG. 3  is a front view illustrating the wireless device  102  of  FIG. 1  in accordance with an embodiment of the invention. As mentioned above, the wireless device  102  can be a data and voice-enabled handheld. The wireless device  102  includes a casing  150 , a display screen  122 , a user interface  170 , a keyboard  132 , a thumbwheel (or trackwheel)  110 , various select buttons  120 , and various signal inputs/outputs  160  (e.g., power connector input, microphone, speaker, data interface input, etc.). Internally, the wireless device  102  includes one or more circuit boards, a CPU  138 , memory  200 , a battery  156 , an antenna, etc. (not shown) which are coupled to the signal inputs/outputs  160 , keyboard  132 , display screen  122 , etc.  
         [0048]      FIG. 4  is a perspective view illustrating an exterior of an RF test fixture  400  for an assembled wireless device  102  in accordance with an embodiment of the invention. The test fixture  400  has a retainer  210  for receiving the wireless device  102 , generally after a portion (e.g., a rear portion) of the casing  150  of the wireless device  102  is removed. The retainer  210  includes a SMA connector  220  mounted thereon for connection to RF test equipment (not shown) via a coaxial cable (not shown). The SMA connector  220  shown in  FIG. 2  is a SMA jack connector. The SMA connector  220  has a center contact  230  separated by a coaxial layer of insulation from a threaded shield contact  240 .  
         [0049]     As will be understood by those of ordinary skill in the art, the SMA connector  220  may be another form of  50  ohm (or other desired impedance) coaxial connector such as a sub-miniature version B (“SMB”) connector.  
         [0050]      FIG. 5  is a perspective view illustrating an interior of the RF test fixture  400  in accordance with an embodiment of the invention. The SMA connector  220  passes through the retainer  210  where the center and shield contacts  230 ,  240  are terminated on a sealed mating assembly  310 . The sealed mating assembly  310  includes, or is otherwise dimensioned to provide, a spacer  320  for aligning a printed circuit board (“PCB”)  330  with spring connectors (not shown) mounted on the wireless device  102 .  
         [0051]     The PCB  330  has one or more central metal pads  340  on which the center contact  230  is terminated. Distributed around these central pads  340  are a number of shield metal pads  350  on which the shield contact  240  is terminated. A probe or pin  360  is connected to one or more of the shield pads  350  for contacting the spring connectors of the wireless device  102 . Each probe  360  may include a spring-mounted tip  370  for improving contact with the spring connectors of the wireless device  102 .  
         [0052]     According to one embodiment of the invention, the shield pads  350  may be distributed around the perimeter of the PCB  330 . By arranging the shield pads  350  around the central pads  340 , the impedance of the connection between the spring connectors and the coaxial connector  220  is maintained at approximately 50 ohms (or other desired impedance).  
         [0053]     The retainer  210  includes one or more clips  380  for removeably connecting the fixture  400  to the wireless device  102 . These clips  380  may correspond to clips (not shown) on the portion of the casing of the wireless device  102  that has been removed. The clips  380  allow the fixture  400  to be securely connected to the wireless device  102  to, for example, enable environmental testing of the wireless device  102 . Environmental testing may include temperature testing, for example. With the fixture  400  securely attached to the wireless device  102 , the wireless device  102  may be tested as though it was fully assembled.  
         [0054]     According to one embodiment of the invention, the spacer  320  may be composed of a polycarbonate material to allow the fixture  400  to be used during temperature testing of the wireless device  102 . Typically, temperature testing may involve cycling the wireless device through temperature extremes often in an enclosed chamber.  
         [0055]     According to another embodiment of the invention, the fixture  400  may be incorporated in automated test equipment (not shown). For example, the fixture  400  can be attached to an arm assembly of the automated test equipment. In this embodiment, the arm assembly can include the coaxial cable for connecting to the coaxial connector  220 . The arm assembly applies the necessary pressure for engaging the clips  380  to secure the fixture  400  to the wireless device  102 . In this embodiment, the fixture  400  may be considered to be a special probe that allows access to internal connectors of the wireless device  102  for RF testing while additionally enabling the wireless device  102  to undergo environmental testing.  
         [0056]     To further illustrate the invention,  FIG. 6  is a partial cross-sectional view of the RF test fixture  400  along line A-A of  FIG. 5 .  FIG. 7  is a top view of the RF test fixture  400  of  FIG. 6 .  FIG. 8  is a back side view of the RF test fixture  400  of  FIG. 6 . And,  FIG. 9  is a left side detail view of the RF test fixture  400  of  FIG. 6 .  
         [0057]     Thus, the present invention provides a test fixture  400  for assembled wireless device testing having an industry standard connection  220  to simple spring contacts. This is accomplished through the use of a mechanical retainer  210  in conjunction with the housing of the wireless device  102  to precisely align a sealed mating assembly  310 . The mating assembly  310  contains pads  340 ,  350  arranged in a coaxial arrangement that contact the spring connectors on the DUT and maintain an approximate  50  ohm impedance (or other desired impedance). Advantageously, the fixture  400  has matching components incorporated directly therein resulting in a compact integrated solution for RF and environmental testing of wireless devices.  
         [0058]     The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.