Abstract:
A radio frequency connector that protrudes through a printed circuit board is comprised of threaded leads. A center conductor is shielded when a shielding connector cap, having a threaded inner portion, screws onto the threaded leads.

Description:
TECHNICAL FIELD OF THE INVENTION  
         [0001]    The present invention is directed, in general, to radio frequency (RF) communication products and, more specifically, to an RF printed circuit board (PCB) connector for use in the printed circuit boards of mobile station devices and wireless network base stations.  
         BACKGROUND OF THE INVENTION  
         [0002]    As new types of wireless communication devices and new communication services are designed, additional bandwidth must be found in order to implement these devices and service. One method used to fit them into the existing frequency spectrum is to use increasingly higher frequencies.  
           [0003]    One of the problems of using higher frequencies is the increased noise problem on printed circuit boards if circuits are not properly shielded. One way that noise can be reduced on printed circuit boards with a radio frequency (RF) connector is to position the end of the conductor flush with the ground plane on the surface of the printed circuit board. An external shield is placed over the center conductor. The shield is then soldered to the backplane of the printed circuit board or bolted to the plate.  
           [0004]    This method, however, requires manual labor, external hardware, as well as additional printed circuit board space. All of these problems add additional cost to the price of the component. There is a resulting need in the art for a more economical apparatus and method for shielding radio frequencies on printed circuit boards.  
         SUMMARY OF THE INVENTION  
         [0005]    To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to reduce the unwanted radiated energy emitted from the center conductor of an RF connector protruding through a printed circuit board (PCB).  
           [0006]    The present invention encompasses a radio-frequency (RF) connector for use in a printed circuit board. The connector is comprised of a center conductor that conducts signals at radio frequencies. The center conductor is surrounded by a plurality of leads that extend through the printed circuit board. Each of the plurality of leads has a threaded portion.  
           [0007]    A shielding connector cap, with a threaded interior portion, engages the threaded portion of the plurality of leads. The connector cap then shields the noise from the center conductor.  
           [0008]    The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.  
           [0009]    Before undertaking the DETAILED DESCRIPTION OF THE INVENTION below, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation; the term “or,” is inclusive, meaning and/or; the phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, wherein like numbers designate like objects, and in which:  
         [0011]    [0011]FIG. 1 illustrates an exemplary circuit card assembly containing RF PCB connectors in accordance with the principles of the present invention;  
         [0012]    [0012]FIG. 2 illustrates a top cross-sectional view of an exemplary RF connector installed in a printed circuit board according to one embodiment of the present invention;  
         [0013]    [0013]FIG. 3 illustrates a side cross-sectional view of an exemplary RF connector installed in a printed circuit board according to one embodiment of the present invention;  
         [0014]    [0014]FIG. 4 illustrates an exemplary wireless mobile station in greater detail according to one embodiment of the present invention; and  
         [0015]    [0015]FIG. 5 illustrates a base station transceiver in an exemplary base station according to one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    [0016]FIGS. 1 through 5, discussed below, and the various embodiments used to describe the principles of the present invention in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the invention. Those skilled in the art will understand that the principles of the present invention may be implemented in any circuit card assembly that handles radio frequency (RF) signals and that contains RF noise sensitive components.  
         [0017]    [0017]FIG. 1 illustrates exemplary circuit card assembly  10 , which contains radio frequency (RF) printed circuit board (PCB) connectors  121 - 124  in accordance with the principles of the present invention. The exemplary circuit card assembly may be used in, for example, a wireless network base station or in a wireless mobile station device, such as a cellular phone. Circuit card assembly  10  comprises printed circuit board  100 , in which integrated circuits  101 - 109  and discrete circuit components  111 - 114  are installed. One or more of integrated circuits  101 - 109  and discrete circuit components  111 - 114  may be highly susceptible to radio frequency (RF) signals that are radiated by one or more of RF PCB connectors  121 - 124 .  
         [0018]    [0018]FIG. 2 illustrates a top cross-sectional view of exemplary RF PCB connector  121  that is installed in printed circuit board  100  according to one embodiment of the present invention. Exemplary RF PCB connector  121  comprises four threaded through-board leads  211 - 214  and center conductor  210 . Threads  220  are on the external surfaces of through-board leads  211 - 214 .  
         [0019]    [0019]FIG. 3 illustrates a side cross-sectional view of exemplary RF PCB connector  121  that is installed in printed circuit board  100  according to one embodiment of the present invention. The side cross-sectional view is along line A-A in FIG. 2. Exemplary RF PCB connector  121  further comprises shielded lead  310  and connector cap  320 .  
         [0020]    Connector cap  320  is threaded over the leads once the leads are inserted through printed circuit board  100 . The present invention extends center conductor  210  and four through-board leads  211 - 214 , spaced 90° apart, through the thickness of the PCB. Through-board leads  211 - 214  are threaded on the ends and protrude through printed circuit board  100 .  
         [0021]    Threads  220  on through-board leads  211 - 214  extend out the other side of the PCB far enough to fasten connector cap  320  over threads  220  of the leads and shield any noise signal from center conductor  210 .  
         [0022]    In the preferred embodiment, the number of ground leads was determined based on an operating frequency of 1.96 GHz. The minimum length space required to shield the frequency of 1.96 GHz is 0.30 inch. For a 0.25 inch conductor, four leads are sufficient to provide adequate shielding at the operating frequency.  
         [0023]    The RF PCB connector of the present invention is not limited to four threaded leads. Alternate embodiments use other operating frequencies that may require different quantities of threaded leads. For example, a lower operating frequency may require only three leads while a higher operating frequency may require five leads.  
         [0024]    The RF PCB connector is also not limited to leads having a plurality of threads. The leads may be comprised of other means for coupling the connector cap to the leads. For example, the leads may have a single ridge over which a ridge or lip on the connector cap slides and engages on a bottom part of the ridge. This can be illustrated in FIG. 3 by removing all but one of the threads on each of the leads and the shielding connector cap.  
         [0025]    The RF PCB connector of the present invention can be used in any electronic device requiring an RF connector on a printed circuit board. For example, wireless mobile stations and the networks in which the mobile stations operate use radio frequencies that may cause problems if not properly shielded. FIGS. 4 and 5 illustrate only two such examples of uses of the RF connector.  
         [0026]    [0026]FIG. 4 illustrates exemplary wireless mobile station  411  according to one embodiment of the present invention. Wireless mobile station  411  comprises antenna  405 , radio frequency (RF) transceiver  410 , transmitter (TX) processing circuitry  415 , microphone  420 , receiver (RX) processor circuitry  425 , speaker  430 , main controller  440 , input/output (I/O) interface (IF)  445 , keypad  450 , and display  455 .  
         [0027]    Wireless mobile station  411  further comprises memory  470  that stores a basic operating system. Wireless mobile station  111  may be a cell phone, a personal digital assistant (PDA) device equipped with a wireless modem, a two-way pager, a personal communication system (PCS) device, or any other conventional wireless mobile system.  
         [0028]    RF transceiver  410  receives, from antenna  405 , an incoming RF signal transmitted by a base station of a wireless communication network. RF transceiver  410  down-converts the incoming RF signal to produce an intermediate frequency (IF) or a baseband signal. The RF PCB connector of the present invention may be used in the RF transceiver in order to reduce effects from undesirable radiated energy.  
         [0029]    The IF or baseband signal is sent to RX processing circuitry  425  that produces a processed baseband signal by filtering, decoding, and/or digitizing the baseband or IF signal to produce a processed baseband signal. RX processing circuitry  425  transmits the processed baseband signal to speaker  430  (i.e., voice data) or to main controller  440  for further processing (i.e., web browsing).  
         [0030]    TX processing circuitry  415  receives analog or digital voice data from microphone  420  or other outgoing baseband data (i.e., web data, e-mail, interactive video game data) from main controller  440 . TX processing circuitry  415  encodes, multiplexes, and/or digitizes the outgoing baseband data to produce a processed baseband or IF signal.  
         [0031]    RF transceiver  410  receives the outgoing processed baseband or IF signal from TX processing circuitry  415 . RF transceiver  410  up-converts the baseband or IF signal to an RF signal that is transmitted via antenna  405 .  
         [0032]    Main controller  440 , in one embodiment, is a microprocessor or microcontroller. Main controller  440  executes basic OS program  271  in order to control the overall operation of wireless mobile station  411 . In one such operation, main controller  440  controls the reception of forward channel signals and the transmission of reverse channel signals by RF transceiver  410 , RX processing circuitry  425 , and TX processing circuitry  415 , in accordance with well known principles.  
         [0033]    Main controller  440  is also coupled to keypad  450  and display unit  455 . Keypad  450  is used by the end-user of the mobile station to enter data into the mobile station. Display  455 , in the preferred embodiment, is a liquid crystal display capable of rendering text and/or at least limited graphics from Web sites. Alternate embodiments use other types of displays.  
         [0034]    Memory  470  is coupled to main controller  440 . Memory  470  may be comprised of solid-state memory such as random access memory (RAM), various types of read only memory (ROM), or Flash RAM. Memory  270  may also include other types of memory such as micro-hard drives or removable media that stores data.  
         [0035]    [0035]FIG. 5 illustrates a base transceiver station (BTS)  520  according to one embodiment of the present invention. Exemplary BTS  520  comprises BTS controller  525 , channel controller  535  that contains channel element  540 , transceiver interface (IF)  545 , RF transceiver unit  550 , and antenna array  555 . Input/output interface (I/O IF)  560  couples BTS  520 .  
         [0036]    BTS controller  525  controls the overall operation of BTS  520  and interfaces with network base station controllers through I/O IF  560 . BTS controller  525  directs the operation of channel controller  535 . Channel controller  535  contains a number of channel elements such as channel element  540 . The channel elements perform bi-directional communications in the forward and reverse links. Depending on the air interface used by system base station, the channel elements engage in time division multiple access (TDMA), frequency division multiple access (FDMA), or code division multiple access (CDMA) communications with the mobile stations in a cell.  
         [0037]    Transceiver IF  545  transfers the bi-directional channel signals between channel controller  535  and RF transceiver  550 . Transceiver IF  545  converts the radio frequency signal from RF transceiver  550  to an intermediate frequency (IF). Channel controller  535  then converts this IF to baseband frequency. The RF PCB connector of the present invention may be used in the RF transceiver in order to reduce effects from undesirable radiated energy.  
         [0038]    Additionally, RF transceiver  550  may contain an antenna selection unit to select among different antennas in antenna array  255  during both transmit and receive operations. Antenna array  555  is comprised of a number of directional antennas that transmit forward link signals, received from RF transceiver  550 , to mobile stations in the sectors covered by the base station. Antenna array  555  also receives reverse link signals from the mobile stations and sends the signals to RF transceiver  550 . In a preferred embodiment of the present invention, antenna array  555  is a multi-sector antenna, such as a six-sector antenna, in which each antenna is responsible for transmitting and receiving in a 60_arc of coverage area.  
         [0039]    The operation of the mobile station and base transceiver station illustrated in FIGS. 4 and 5 are well known in the art and not discussed further. These figures are for illustration purposes only and do not limit the use of RF PCB connector of the present invention.  
         [0040]    In summary, the shielded connector of the present invention reduces the need for complicated external shielding techniques in mechanical designs of printed circuit boards. Threading the leads and attaching a threaded cap to the leads shields the center conductor. This reduces the unwanted radiated energy emitted from the center conductor, thereby increasing the effectiveness of the desired signal.  
         [0041]    The present invention allows more flexibility in the placement of noise sensitive components. This is accomplished with no increase to the overall cost of parts and installation of an existing RF connector. In fact, a reduction to the overall cost of the system results from the simpler design.  
         [0042]    Although the present invention has been described in detail, those skilled in the art should understand that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention in its broadest form.