Patent Publication Number: US-8983554-B2

Title: Mobile wireless communications device with RF immune charging contacts

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of communications devices, and more particularly, to mobile wireless communications devices and related methods. 
     BACKGROUND OF THE INVENTION 
     Cellular communication systems continue to grow in popularity and have become an integral part of both personal and business communications. Cellular telephones allow users to place and receive phone calls most anywhere they travel. Moreover, as cellular telephone technology is increased, so too has the functionality of cellular devices. For example, many cellular devices now incorporate Personal Digital Assistant (PDA) features such as calendars, address books, task lists, calculators, memo and writing programs, etc. These multi-function devices usually allow users to send and receive electronic mail (email) messages wirelessly and access the internet via a cellular network and/or a wireless local area network (WLAN), for example. 
     As the functionality of cellular communications devices continues to increase, so too does demand for smaller devices that are easier and more convenient for users to carry. The circuit boards and associated electronic components thereon are becoming increasingly reduced in size and placed closer together. These components include antennae, RF components, power amplifiers, antenna switches, and other electronic components that pick up conductive energy and create interference within various circuits and components. For example, some components could pick up conducted energy directly from a power amplifier circuit, the charging contacts of a battery, antenna contacts, or from the radiated energy emitted by an antenna. This unwanted reception of conducted or near field radiated energy from power amplifiers, antennae or other components is particularly problematic in a packet burst transmission as part of a Global System for Mobile communications (GSM) system, including the 450 MHz, 900 MHz, 1800 MHz and 1900 MHz frequency bands. Other issues arise with modulation schemes that use In-phase (I) and Quadrature (Q) circuits, creating linearity issues with power amplifiers and poor antenna match. This can cause degradation of TRP (total radiated power) and raise harmonic interference issues because of the higher non-linearity of a power amplifier as an example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and advantages will become apparent from the detailed description which follows, when considered in light of the accompanying drawings in which: 
         FIG. 1  is a schematic block diagram of an example of a mobile wireless communications device configured as a handheld device and illustrating basic internal components thereof as a non-limiting example. 
         FIG. 2  is a front elevation view of the mobile wireless communications device of  FIG. 1 . 
         FIG. 3  is a schematic block diagram showing basic functional circuit components that can be used in the mobile wireless communications device of  FIGS. 1-2 . 
         FIG. 4  is a fragmentary and isometric view of the rear or back section of a housing case as part of a housing for the mobile wireless communications device such as shown in  FIGS. 1-3  and showing an example of the relative position of the antenna and battery charging contacts in a non-limiting example. 
         FIG. 5  is a fragmentary, side elevation view of a battery charging contact and its spring connector and antenna on the housing case and showing a filter positioned near the charging contacts to minimize transmission harmonics emission and receiver de-sense. 
         FIG. 6  is a block diagram of a conventional In-phase and Quadrature (I/Q) modulation and power amplification circuit showing one power amplification circuit after combining I/Q signals. 
         FIG. 7  is a block diagram of an In-phase and Quadrature modulation and power amplification circuit that includes a separate power amplifier circuit for each of the In-phase and Quadrature circuits in accordance with a non-limiting example. 
         FIGS. 8 and 9  are side elevation views of prior art antenna contacts used with different mobile wireless communications devices. 
         FIG. 10  is a schematic circuit diagram of the equivalent circuit for the prior art antenna contacts shown in  FIGS. 8 and 9 . 
         FIG. 11  is a fragmentary, isometric view of an antenna contact that, in accordance with a non-limiting example, ensures good radio frequency (RF) and mechanical performance. 
         FIG. 12  is another fragmentary, isometric view of the antenna contact as shown in  FIG. 11  and showing the added conductive Electromagnetic Interference (EMI) material to reduce inductance and variation resulting from an extended RF stub. 
         FIG. 13  is a schematic circuit diagram of an equivalent RF circuit of the antenna contacts in accordance with a non-limiting example shown in  FIGS. 11 and 12  that ensures good radio frequency (RF) and mechanical performance. 
         FIG. 14  is another fragmentary, isometric view of the antenna contact such as shown in  FIG. 12  and showing a better view of the EMI material added near the contact point and also showing relative dimensions in a non-limiting example. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present description is made with reference to the accompanying drawings, in which preferred embodiments are shown. However, many different embodiments may be used, and thus the description should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. Like numbers refer to like elements throughout. 
     In accordance with a non-limiting aspect, a mobile wireless communications device includes a housing and at least one circuit board carried by the housing. Radio frequency (RF) circuitry is carried by the at least one circuit board and includes a transmitter and receiver. A processor is carried by the at least one circuit board and operative with the RE circuitry. An antenna is mounted within the housing and operative with the RF circuitry. A charging circuit is mounted within the housing and charges a battery carried by and powers the mobile wireless communications device. It includes at least one charging contact carried by the housing and configured for engaging an external charging cradle when connected thereto. It includes an internal connector extending to at least one circuit board and connecting the charging circuitry. An RF filter is connected to the charging contact and includes a ferrite material surrounding at least a portion of the internal connector to minimize RF coupling from the at least one charging contact to the antenna and reduce transmitter harmonics emission and receiver de-sense. 
     The housing can include a lower end to which the antenna and at least one charging contact are positioned in close proximity to each other. The housing case can have a lower edge mounting the antenna. The antenna can extend over the lower edge and the at least one charging contact is supported adjacent the lower edge to which the antenna is mounted. The antenna could be formed as a substantially n-shaped antenna extending over the lower edge. 
     In another aspect, the charging contact can be formed as a spring connector that extends to the at least one circuit board and is not surrounded by the ferrite material forming the RE filter. The at least one charging contact could be formed as two spaced charging contacts with opposite polarity. A respective RF filter can be connected to each respective charging contact. The RF filter in one aspect can be substantially cylindrically configured and surround and engage the internal connector. The housing can include an internal surface and an RF filter support extending from the internal surface to which the ferrite material is secured. The REF filter support could be formed as a cylindrical wall that supports the ferrite material. 
     In yet another aspect, the RF circuitry can be formed as a transceiver chip whether a single or multiple chip set. A battery charging pad can be carried by the at least one circuit board and connected to charging circuitry and the internal connector. The RF circuitry can be operative for generating global systems for mobile (GSM) packet bursts. 
     In another aspect, the housing case is substantially rectangular configured and has a rear surface, longitudinal side edges and a lower end forming a lower edge. A battery opening is contained in the rear surface to which a battery for powering the device is received. 
     A brief description will now proceed relative to  FIGS. 1-3 , which discloses an example of a mobile wireless communications device, for example, a handheld portable cellular radio, which can incorporate non-limiting examples of the various circuits, including the improved battery charging contact circuit. In-phase and Quadrature Modulation and Power Amplification circuit, and antenna contact as later described.  FIGS. 1-3  are representative non-limiting examples of the many different types of functional circuit components and their interconnection, and operative for use in the circuits of the mobile wireless communications device that can incorporate the improvements, advantages and features as described. 
     Referring initially to  FIGS. 1 and 2 , an example of a mobile wireless communications device  20 , such as a handheld portable cellular radio with improvements and advantages as described below is set forth. This device  20  illustratively includes a housing  21  having an upper portion  46  and a lower portion  47 , and at least one dielectric substrate (i.e., circuit board)  67 , such as a conventional printed circuit board (PCB) substrate, for example, carried by the housing. A number of different circuit boards can be used for supporting different components. For example, one circuit board could support the microprocessor and RF components, another circuit board could be formed as an antenna circuit board, and yet another circuit board could be formed as a circuit board for supporting different components such as a keyboard. 
     A housing (not shown in detail) would typically cover and enclose various components, such as circuit boards and an antenna. The housing includes a housing case, for example, a plastic case. The housing case could support a separate housing cover for front and rear sides depending on the type of design. Any type of housing or housing case will allow access to any circuit board and supports the one or more circuit boards. A battery opening provides access for a battery to power the device. The housing case could support an antenna in one non-limiting example, such as at its lower edge. The term circuit board  67  as used hereinafter can refer to any dielectric substrate, PCB, ceramic substrate or other circuit carrying structure for carrying signal circuits and electronic components within the mobile wireless communications device  20 . The illustrated housing  21  is a static housing, for example, but it should be understood that a flip or sliding housing can be used as is typical in many cellular and similar telephones. These and other housing configurations with different housing case designs may be used. 
     Circuitry  48  is carried by the circuit board  67 , such as a microprocessor, memory, one or more wireless transceivers (e.g., cellular, WLAN, etc.), which includes RF circuitry, including audio and power circuitry, and in this aspect, including any keyboard circuitry. This circuitry could also generally be termed RF circuitry. It should be understood that, as noted before, keyboard circuitry could be on a separate keyboard, etc., as will be appreciated by those skilled in the art. The different components as described can also be distributed on one circuit board or among a plurality of different circuit boards as noted before. A battery (not shown) is also preferably carried by the housing  21  for supplying power to the circuitry  48 . The term RF circuitry could encompass the interoperable RF transceiver circuitry, including receive and transmit circuits and power circuitry, including charging circuitry and audio circuitry, including In-phase and Quadrature circuits that include respective power amplifier circuits for respective In-phase and Quadrature circuits. 
     In one aspect, an audio output transducer  49  (e.g., a speaker) is carried by an upper portion  46  of the housing  21  and connected to the circuitry  48 . One or more user input interface devices, such as a keypad (keyboard)  23  ( FIG. 2 ), is also preferably carried by the housing  21  and connected to the RF circuitry  48 . The term keypad as used herein also refers to the term keyboard, indicating the user input devices having lettered and/or numbered keys commonly known and other embodiments, including multi-top or predictive entry modes. Other examples of user input interface devices include a scroll wheel  37  and a back button  36 . Of course, it will be appreciated that other user input interface devices (e.g., a stylus or touch screen interface) may be used in other embodiments. 
     An antenna and associated antenna circuit  45  ( FIG. 1 ) is preferably supported within the housing and in one aspect at a lower portion  47  in the housing, such as on the housing case lower edge. The antenna can be formed as a pattern of conductive traces that make an antenna circuit, which physically forms the antenna. It is operatively connected to the circuitry  48  on the main circuit board  67  or other circuitry on other boards. In one non-limiting example, the antenna could be formed on a separate antenna circuit board or an antenna circuit board section that extends from the main circuit board at the lower portion of the housing. By placing the antenna  45  adjacent the lower portion  47  of the housing  21 , the distance is advantageously increased between the antenna and the user&#39;s head when the phone is in use to aid in complying with applicable SAR requirements. Also, a separate keyboard circuit board could be used as noted before. 
     More particularly, a user will typically hold the upper portion of the housing  21  very close to their head so that the audio output transducer  49  is directly next to the ear. Yet, the lower portion  47  of the housing  21  where an audio input transducer (i.e., microphone) is located need not be placed directly next to a user&#39;s mouth, and can be held away from the user&#39;s mouth. That is, holding the audio input transducer close to the user&#39;s mouth may not only be uncomfortable for the user, but it may also distort the user&#39;s voice in some circumstances. 
     In some designs, the antenna  45  is placed adjacent the lower portion  47  of the housing  21  to allow for less impact on antenna performance due to blockage by a user&#39;s hand. Users typically hold cellular phones towards the middle to upper portion of the phone housing, and are therefore more likely to put their hands over such an antenna than they are an antenna mounted adjacent the lower portion  47  of the housing  21 . Accordingly, more reliable performance may be achieved from placing the antenna  45  adjacent the lower portion  47  of the housing  21 . 
     Another benefit of this type of configuration is that it provides more room for one or more auxiliary input/output (I/O) devices  50  to be carried at the upper portion  46  of the housing. Furthermore, by separating the antenna  45  from the auxiliary I/O device(s)  50 , this may allow for reduced interference therebetween. 
     Some examples of auxiliary I/o devices  50  include a WLAN (e.g., Bluetooth, IEEE 802.11) antenna for providing WLAN communication capabilities, and/or a satellite positioning system (e.g., GPS, Galileo, etc.) antenna for providing position location capabilities, as will be appreciated by those skilled in the art. Other examples of auxiliary I/O devices  50  include a second audio output transducer (e.g., a speaker for speaker phone operation), and a camera lens for providing digital camera capabilities, an electrical device connector (e.g., USB, headphone, secure digital (SD) or memory card, etc.). 
     It should be noted that the term “input/output” as used herein for the auxiliary I/O device(s)  50  means that such devices may have input and/or output capabilities, and they need not provide both in all embodiments. That is, devices such as camera lenses may only receive an optical input, for example, while a headphone jack may only provide an audio output. 
     The device  20  further illustratively includes a display  22 , for example, a liquid crystal display (LCD) carried by the housing  21  and connected to the circuitry  48 . A back button  36  and scroll wheel  37  can also be connected to the circuitry  48  for allowing a user to navigate menus, text, etc., as will be appreciated by those skilled in the art. The scroll wheel  37  may also be referred to as a “thumb wheel” or a “track wheel” in some instances. The keypad  23  illustratively includes a plurality of multi-symbol keys  24  each having indicia of a plurality of respective symbols thereon. The keypad  23  also illustratively includes an alternate function key  25 , a next key  26 , a space key  27 , a shift key  28 , a return (or enter) key  29 , and a backspace/delete key  30 . 
     The next key  26  is also used to enter a “*” symbol upon first pressing or actuating the alternate function key  25 . Similarly, the space key  27 , shift key  28  and backspace key  30  are used to enter a “0” and “#”, respectively, upon first actuating the alternate function key  25 . The keypad  23  further illustratively includes a send key  31 , an end key  32 , and a convenience (i.e., menu) key  39  for use in placing cellular telephone calls, as will be appreciated by those skilled in the art. 
     Moreover, the symbols on each key  24  are arranged in top and bottom rows. The symbols in the bottom rows are entered when a user presses a key  24  without first pressing the alternate function key  25 , while the top row symbols are entered by first pressing the alternate function key. As seen in  FIG. 2 , the multi-symbol keys  24  are arranged in the first three rows on the keypad  23  below the send and end keys  31 ,  32 . Furthermore, the letter symbols on each of the keys  24  are arranged to define a QWERTY layout. The letters on the keypad  23  are presented in a three-row format, with the letters of each row being in the same order and relative position as in a standard QWERTY keypad. 
     Each row of keys (including the fourth row of function keys  25 - 29 ) is arranged in five columns in this non-limiting example. The multi-symbol keys  24  in the second, third, and fourth columns of the first, second, and third rows have numeric indicia thereon (i.e., 1 through 9) accessible by first actuating the alternate function key  25 . Coupled with the next, space, and shift keys  26 ,  27 ,  28 , which respectively enter a “*”, “0”, and “#” upon first actuating the alternate function key  25 , as noted above, this set of keys defines a standard telephone keypad layout, as would be found on a traditional touch-tone telephone, as will be appreciated by those skilled in the art. 
     Accordingly, the mobile wireless communications device  20  as described may advantageously be used not only as a traditional cellular phone, but it may also be conveniently used for sending and/or receiving data over a cellular or other network, such as Internet and email data, for example. Of course, other keypad configurations may also be used in other embodiments. Multi-tap or predictive entry modes may be used for typing e-mails, etc. as will be appreciated by those skilled in the art. 
     In one non-limiting aspect, the antenna  45  is preferably formed as a multi-frequency band antenna, which provides enhanced transmission and reception characteristics over multiple operating frequencies. More particularly, the antenna  45  is designed to provide high gain, desired impedance matching, and meet applicable SAR requirements over a relatively wide bandwidth and multiple cellular frequency bands. By way of example, in one non-limiting example, the antenna  45  preferably operates over five bands, namely a 850 MHz Global System for Mobile Communications (GSM) band, a 900 MHz GSM band, a DCS band, a PCS band, and a WCDMA band (i.e., up to about 2100 MHz), although it may be used for other bands/frequencies as well. To conserve space, the antenna  45  may advantageously be implemented in three dimensions although it may be implemented in two-dimensional or planar embodiments as well. In one non-limiting example, it is L-configured and positioned at the lower portion or edge of the support case. 
     The mobile wireless communications device shown in  FIGS. 1 and 2  can incorporate email and messaging accounts and provide different functions such as composing e-mail, PIN messages, and SMS messages. The device can manage messages through an appropriate menu that can be retrieved by choosing a messages icon. An address book function could add contacts, allow management of an address book, set address book options and manage SIM card phone books. A phone menu could allow for the making and answering of phone calls using different phone features, managing phone call logs, setting phone options, and viewing phone information. A browser application could permit the browsing of web pages, configuring a browser, adding bookmarks, and changing browser options. Other applications could include a task, memo pad, calculator, alarm and games, as well as handheld options with various references. 
     A calendar icon can be chosen for entering a calendar program that can be used for establishing and managing events such as meetings or appointments. The calendar program could be any type of messaging or appointment/meeting program that allows an organizer to establish an event, for example, an appointment or meeting. 
     A non-limiting example of various functional components that can be used in the exemplary mobile wireless communications device  20  of  FIGS. 1 and 2  is further described in the example below with reference to  FIG. 3 . The device  20  illustratively includes a housing  120  shown in outline by the dashed lines, a keypad  140 , and an output device  160 . The output device  160  shown is preferably a display, which is preferably a full graphic LCD. Other types of output devices may alternatively be used. A processing device  180  such as a microprocessor is contained within the housing  120  and is coupled between the keypad  140  and the display  160 . The processing device  180  controls the operation of the display  160 , as well as the overall operation of the mobile device  20 , in response to actuation of keys on the keypad  140  by the user. 
     The housing  120  may be elongated vertically, or may take on other sizes and shapes (including clamshell housing structures). The keypad may include a mode selection key, or other hardware or software for switching between text entry and telephony entry. 
     In addition to the processing device  180 , other parts of the mobile device  20  are shown schematically in  FIG. 3 . These include a communications subsystem  101 ; a short-range communications subsystem  102 ; the keypad  140  and the display  160 , along with other input/output devices  106 ,  108 ,  110  and  112 ; as well as memory devices  116 ,  118  and various other device subsystems  121 . The mobile device  20  is preferably a two-way RP communications device having voice and data communications capabilities. In addition, the mobile device  20  preferably has the capability to communicate with other computer systems via the Internet. 
     Operating system software executed by the processing device  180  is preferably stored in a persistent store, such as the flash memory  116 , but may be stored in other types of memory devices, such as a read only memory (ROM) or similar storage element. In addition, system software, specific device applications, or parts thereof, may be temporarily loaded into a volatile store, such as the random access memory (RAM)  118 . Communications signals received by the mobile device may also be stored in the RAM  118 . 
     The processing device  180 , in addition to its operating system functions, enables execution of software applications  130 A- 130 N on the device  20 . A predetermined set of applications that control basic device operations, such as data and voice communications  130 A and  130 B, may be installed on the device  20  during manufacture. In addition, a personal information manager (PIM) application may be installed during manufacture. The PIM is preferably capable of organizing and managing data items, such as e-mail, calendar events, voice mails, appointments, and task items. The PIM application is also preferably capable of sending and receiving data items via a wireless network  141 . Preferably, the PIM data items are seamlessly integrated, synchronized and updated via the wireless network  141  with the device user&#39;s corresponding data items stored or associated with a host computer system. 
     Communication functions, including data and voice communications, are performed through the communications subsystem  101 , and possibly through the short-range communications subsystem. The communications subsystem  101  includes a receiver  150 , a transmitter  152 , and one or more antennae  154  and  156 . In addition, the communications subsystem  101  also includes a processing module, such as a digital signal processor (DSP)  158 , and local oscillators (LOs)  161 . The specific design and implementation of the communications subsystem  101  is dependent upon the communications network in which the mobile device  20  is intended to operate. For example, the mobile device  20  may include a communications subsystem  101  designed to operate with the Mobitex™, Data TAC™ or General Packet Radio Service (GPRS) mobile data communications networks, and also designed to operate with any of a variety of voice communications networks, such as AMPS, TDMA, CDMA, PCS, GSM, etc. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile device  20 . 
     Network access requirements vary depending upon the type of communication system. For example, in the Mobitex and DataTAC networks, mobile devices are registered on the network using a unique personal identification number or PIN associated with each device. In GPRS networks, however, network access is associated with a subscriber or user of a device. A GPRS device therefore requires a subscriber identity module, commonly referred to as a SIM card, in order to operate on a GPRS network. 
     When required network registration or activation procedures have been completed, the mobile device  20  may send and receive communications signals over the communication network  141 . Signals received from the communications network  141  by the antenna  154  are routed to the receiver  150 , which provides for signal amplification, frequency down conversion, filtering, channel selection, etc., and may also provide analog to digital conversion. Analog-to-digital conversion of the received signal allows the DSP  158  to perform more complex communications functions, such as demodulation and decoding. In a similar manner, signals to be transmitted to the network  141  are processed (e.g., modulated and encoded) by the DSP  158  and are then provided to the transmitter  152  for digital to analog conversion, frequency up conversion, filtering, amplification and transmission to the communication network  141  (or networks) via the antenna  156 . 
     In addition to processing communications signals, the DSP  158  provides for control of the receiver  150  and the transmitter  152 . For example, gains applied to communications signals in the receiver  150  and transmitter  152  may be adaptively controlled through automatic gain control algorithms implemented in the DSP  158 . 
     In a data communications mode, a received signal, such as a text message or web page download, is processed by the communications subsystem  101  and is input to the processing device  180 . The received signal is then further processed by the processing device  180  for an output to the display  160 , or alternatively to some other auxiliary I/O device  106 . A device user may also compose data items, such as e-mail messages, using the keypad  140  and/or some other auxiliary I/O device  106 , such as a touchpad, a rocker switch, a thumb-wheel, or some other type of input device. The composed data items may then be transmitted over the communications network  141  via the communications subsystem  101 . 
     In a voice communications mode, overall operation of the device is substantially similar to the data communications mode, except that received signals are output to a speaker  110 , and signals for transmission are generated by a microphone  112 . Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on the device  20 . In addition, the display  160  may also be utilized in voice communications mode, for example to display the identity of a calling party, the duration of a voice call, or other voice call related information. 
     Any short-range communications subsystem enables communication between the mobile device  20  and other proximate systems or devices, which need not necessarily be similar devices. For example, the short-range communications subsystem may include an infrared device and associated circuits and components, or a Bluetooth™ communications module to provide for communication with similarly-enabled systems and devices. 
       FIG. 4  shows a section of the mobile wireless communications device such as shown in  FIGS. 1-3  and showing the relative position of the antenna and battery charging contacts on a portion of the back or rear section of the housing case  200  as part of the housing forming the mobile wireless communications device. A rear cover in some non-limiting examples could be inserted over the illustrated housing case. It is shown removed in this non-limiting example. In other aspects, the housing case could include integrated or separate front and rear housing covers depending on specific design options. 
     As illustrated in this one particular configuration, the housing case  200  is substantially rectangular configured and includes opposing ends and longitudinal edges and includes an end formed as a lower edge  202  corresponding, for example, to the lower portion  47  of the mobile wireless communications device of  FIG. 1 . The antenna  204  in this example is supported at the lower edge  202  of the housing case  200  and configured as an L-shaped antenna in cross-section and extends over the lower edge  202  of the housing case as illustrated. In this example, the antenna  204  extends substantially along the entire lower edge  202  except at the longitudinal edges. 
     Two battery charging contacts  208 ,  210  are positioned on the housing case  200  and operable to engage charging contacts (not shown) such as part of a charging cradle. The charging contacts  208 ,  210  are separated by an insulator strip  211  in this example. The battery charging contacts  208 ,  210  are placed in close proximity to the antenna  204  as illustrated in  FIG. 4 . On the housing case  200 , the central section is defined by a battery well  214  to which a battery for powering the device could be received, and shown by the rectangular line  216  and could also define an area in the housing case  200  for access to various components, including any PCB boards as described relative to  FIGS. 1-3 . 
     Charging contacts are a feature of many mobile wireless communications devices such as shown and described relative to  FIGS. 1-3 . As shown by the close proximity between the battery charging contacts  208 ,  210  and the antenna  204  in  FIG. 4 , radio frequency (RF) coupling occurs at the charging contacts and can affect the antenna performance and cause transmitter circuitry harmonics emissions and receiver circuitry de-sense. The charging contacts  208 ,  210  are typically also positioned close to a power amplifier circuit such as described relative to  FIGS. 1-3 , which also causes various RF and other interference issues with the internal circuitry and antenna. 
     As shown in  FIG. 5 , each of the charging contacts  208 ,  210  includes an internal connector as an electrical conductor indicated generally at  220  that extends downward and includes a lower internal spring (e.g., biased) connector  222  that connects to a battery charging pad  224  positioned on the printed circuit board  226 . Thus, each internal connector  220  with its associated spring connector  222  segment forms a biased electrical connector between the exposed surface of the contact such as shown by the reference numerals  208  and  210  in  FIG. 4  and battery charging pads on the circuit board. In this side elevation view, only one charging contact and associated battery charging pad is illustrated. The battery charging pad  224  connects to battery charging circuitry  225  such as by signal traces on the circuit board. The charging circuitry  225  could be separate from the circuit board in some examples and connected by lead wires to battery charging pad  224 . It should be understood that in this example,  FIG. 5  shows only one charging contact in this elevation view, but each charging contact could have an internal connector  220  and its associated lower section formed as a spring connector  222  connected to a respective battery charging pad  224 . 
     The battery charging contacts  208 ,  210 , and any associated battery charging pad  224  and the internal connector  220  and its associated spring connector  222  can operate similar to an antenna, creating some interference issues. The charging contacts  208 ,  210 , their internal connector  220  and associated spring connector  222  and the battery charging pad  224  connect to the charging circuit  225 , which typically has a low impedance for RF it is typically close to the antenna, and heavily couples energy to the antenna  204  and loads the antenna impedance. A respective charging contact could have a respective polarity as understood by those skilled in the art. 
     Any type of spring connector such as the illustrated internal connector  220  with its associated spring connector  222  can resonate at the band of interest and cause interference. The battery charging contacts  208 ,  210  with their internal connectors and charging pads can pick up digital noise from the digital circuits as part of a mobile wireless communications device where energy is supplied from the battery and coupled back with any power amplifier harmonics to the battery and battery charging circuit. This creates even greater digital noise and desensitizes any radio frequency circuitry associated with the receiver. Also, during any transmission, a power amplifier can eject harmonics and these harmonics can be coupled to the charging contacts  208 ,  210 . 
     Some proposals to reduce interference have used ferrite beads positioned on printed circuit boards, for example, on the signal traces formed on circuit boards, to reduce the harmonics and interference. Ferrite beads on a circuit board help reduce noise coupled beyond the ferrite beads, for example, close to any internal connectors including spring connectors, charging contacts or battery charging pads. The ferrite beads, however, are positioned on the circuit board and not at the internal connectors and associated spring connectors and charging contacts for the charging circuit. Thus, the RF impedance is still increased at that point in some designs. 
     As shown in  FIG. 5 , an RF filter  230  as a core of ferrite material is placed at each of the respective charging contacts  208 ,  210  at a portion of the internal connector  220  above the associated spring connector  222  in this non-limiting example and will prevent RF coupling to the antenna  202  and the associated battery charging contact and its internal connector and associated spring connector  222  and any associated battery charging pads. This ferrite material will also prevent high impedance and prevent noise from being ejected that will de-sense the receiver circuit or radiate harmonics during the transmit mode. 
     The L-shaped antenna  204  as shown in  FIG. 4  in this example is wrapped around the lower edge  202  of the support case  200  ( FIG. 5 ). The PCB board  226  as illustrated includes the various RF components as described relative to  FIGS. 1-3 , including connection lines and other components. These components are not shown in detail in  FIG. 5 . The battery charging contacts  208 ,  210  are shown closely positioned near the antenna  204  and supported by the housing case  200  and, as explained before, include the downward extending internal connector  220  and its associated lower section formed as a spring connector  222  and such that battery charging contacts  208 ,  210  electrically engage a battery charging pad  224  on the printed circuit board  226  as part of the battery charging circuit. As illustrated, the battery charging pad  224  connects to part of charging circuit  225 , which is positioned on the circuit board in this non-limiting example, but as noted before, could be supported elsewhere in the housing. 
     As illustrated, an internal section of the housing corresponding to the housing case  200  includes a downward extending RF filter support  232  for the ferrite material as an RF filter  230 , e.g., a “holster,” as a non-limiting example in this instance, which could be formed as a cylindrical wall  234  that extends around a substantial portion of the internal connector to hold the ferrite material (formed cylindrically in this example to fit within the filter support) in place relative to the battery charging contacts and their internal connector  220  up to the lower spring connector  222 . The RF filter  230  formed from the ferrite material does not interfere with the biasing action of the internal connector in this non-limiting example since the spring connector is not covered. Other configurations besides a cylinder could be used to form the RF filter support  232  as part of the housing case. The ferrite material  230  is received in this RE filter support and secured thereby and acts similar to a ferrite bead relative to the internal connector  220  and its associated spring connector  222  as part of the battery charging contact  208  and prevents RE coupling. The ferrite material as an RE filter  230  acts similar to a ferrite bead, such as placed directly on the circuit board, but instead is a ferrite material that encompasses a portion of the internal connector  220 . It could also encompass part of the associated spring connector  222  as long as it did not interfere with any biasing function of the spring connector. 
     In this non-limiting example, the spring connector  222  as part of the internal connector  220  is used to add resilience to the overall connector. The mobile wireless communications device during charging is typically placed in a charging cradle (in this example), and resilience in movement helps ensure contact for charging. The ferrite based RF filter  230  is incorporated with the charging contacts  208 ,  210  and provides the high RF impedance across the frequency bands of interest such that the charging contacts will present high impedance to the antenna. Therefore, the antenna performance will not be degraded. 
     This RF filter  230  is formed in this non-limiting example from a ferrite material that blocks the transmission (Tx) harmonics coupled from any RF power amplifier to any traces or connection lines formed on the printed circuit board such as from the battery charging pad and prevent any energy from radiating by the charging contacts. In a radio frequency (RF) receive mode, most of the digital noise coupled from the processor or other CPU and other high frequency digital circuits to the charging contacts  208 ,  210  will be eliminated by the ferrite RF filter  230 , which prevents receiver de-sensing due to the noise picked-up by the antenna  204 . By implementing this RF filter  230  near the charging contacts  208 ,  210  as shown in  FIG. 5 , these technical problems are minimized as compared to a more conventional technique of placing ferrite beads on a printed circuit board. Thus, the charging contacts  208 ,  210  are designed such as in the non-limiting example shown in  FIG. 5  to incorporate the RF filter  230 . 
     Referring now to  FIG. 6 , there is illustrated a block diagram of a conventional In-phase and Quadrature (I/Q) modulation and power amplification circuit illustrated generally at  300  that is typically used in many different types of communications devices, especially lower power mobile wireless communications devices. The circuit  300  has one power amplifier circuit after the In-phase and Quadrature modulation and mixing and power combining. 
       FIG. 6  shows this conventional I/Q modulation and power amplification circuit  300 . It has In-phase and Quadrature inputs (I) and (Q) for a respective In-phase circuit  302  and Quadrature circuit  304  that each include a respective digital-to-analog converter (DAC)  310 ,  312 , low pass filter  314 ,  316  and mixer  318 ,  320  as illustrated. A local oscillator  330  generates a local oscillator (LO) signal into a frequency divider  332 , which passes the resulting and divided signals into the respective mixers  318 ,  320  as illustrated. The frequency divider  332  provides for +45 and −45 phase/frequency adjustment for I and Q modulation. 
     The output from the mixers  318 ,  320  are combined (or summed) at a power combiner  340  into one signal that is then bandpass filtered within a respective bandpass filter  342 . One or more RF power amplifiers form a power amplifier circuit  350  amplifies the signal after bandpass filtering. The amplified signal is then filtered in a low pass filter  352 . The filtered signal is passed to further RF circuits for other processing, including an antenna as part of any transmitter circuitry for signal transmission over-the-air. The modulation and power amplification circuit  300  shown in  FIG. 6  may have linearity issues with the power amplifier (PA) circuit  350  and requires a more flexible IQ modulation scheme. This can be especially relevant when the power amplifier circuit design is used for 8 PSK (phase shift keying), quadrature amplitude modulation (QAM) and similar modulation schemes, typical in some lower power communications devices. 
     This conventional circuit  300  also may have a poor antenna match degrading total radiated power (TRP) and cause less efficiency because of the current power amplifier drawbacks, making it difficult to make improvements in radio frequency transmitter performance and battery life. Also, this type of conventional circuit  300  may have harmonics issues because of the higher non-linearity of the power amplifier. Some very high power I/Q modulation circuits such as in large and powerful base stations may use multiple power amplifiers that are power combined into an antenna, but they typically incorporate complex circuit features such as feed forward, feedback, free-distortion, complex mixing and complex power amplifier circuits. Those types of solutions are not always adequate for lower power mobile wireless communications device. Some communications circuits for I/Q modulation incorporate parallel output stages. These are usually targeted to achieve better linearity in any power amplifier circuit. The parallel output stages are sometimes used for heat control, increased power output, signal quality, peak power improvement and similar aspects. These circuits still may suffer drawbacks and may not be as reliable or adapted for lower power application as indicated above. 
       FIG. 7  is a block diagram of an IQ modulation and power amplification circuit  400  in accordance with a non-limiting aspect that includes I/Q signal inputs and an In-phase circuit  402  and Quadrature circuit  404 , including the basic components in each I/Q circuit  402 ,  404  of a respective DAC  410 ,  412 , LPF  414 ,  416  and mixer  418 ,  420 . The components are similar to components shown in  FIG. 6 , but with modifications that could be made as a result of the changes in each I/Q circuit  402 ,  404  to include a power amplifier circuit as described below. 
     Each I/Q circuit  402 ,  404  includes a power amplifier circuit  450   a ,  450   b  that is used only for amplifying respective I or Q signals in the respective I/Q circuits  402 ,  404 . The respective power amplifier circuit  450   a ,  450   b  is positioned into each of the respective In-phase and Quadrature circuits  402 ,  404 . The local oscillator  430  and frequency divider circuits  432  can be similar as with the circuit of  FIG. 6  with modifications as are necessary. After mixing within respective mixers  418 ,  420 , the respective I and Q signals are each bandpass filtered within the respective bandpass filters  442   a ,  442   b , and then each power amplified by respective power amplifier circuits  450   a ,  450   b  such that the separate In-phase and Quadrature signals are power amplified separately and not after being combined as in the circuit of  FIG. 6 . Afterward, the respective I and Q signals are power combined within a power combiner  460  and the resultant signal filtered within a low pass filter  462 . 
     This I/Q modulation and power amplification circuit  400  in this non-limiting example uses two separate power amplifier circuits  450   a ,  450   b  with 3 dB less output power as compared to a more conventional single power amplifier circuit positioned after combining such as shown in  FIG. 6 , resulting in better linearity of the power amplifier circuit and increased DC power efficiency, while still maintaining the same output power through a 3 dB power combiner  460  as a non-limiting example. The power combiner  460  isolates the output from the input such that the circuit  400  can prevent a poor antenna match from directly affecting the power amplifier and radio frequency (RF) performance. With higher and more efficient power amplifier circuits  450   a ,  450   b  as described for each I/Q circuit  402 ,  404 , it is possible to gain longer battery life. Because it is possible to use more linear power amplifiers with the design as shown in  FIG. 7 , there is less harmonic emission from the power amplifier output. 
     Not only is IQ modulation achieved with the circuit design shown in  FIG. 7 , but also digital amplitude, frequency and phase modulation is achieved in an efficient manner. The better linearity and power-added efficiency occurs because of using smaller power amplifier circuits such as associated with a mobile wireless communications device to achieve a desired output power, for example, greater than 33 dBm. This I/Q modulation and power amplification circuit  400  allows a more flexible digital modulation for different modulation schemes with similar hardware architectures. It is possible to implement the circuit  400  on a single transceiver chip such as shown by the line at  470  due to the use of the respective power amplifier circuits  450   a ,  450   b , transmitting 3 dB less of RF power than a normal single power amplifier circuit  350  such as shown in  FIG. 6 . The IQ modulation and power amplification circuit  400  shown in  FIG. 7  includes as a non-limiting example a 3 dB power combiner  460  such as a quadrature hybrid power combiner and provides an easier power amplifier match for better output power, efficiency and immunity to mobile antenna impedance change. The power combiner  460  also allows the cancellation of even order transmit harmonics, which in turn, will make any harmonics filter design easier with less insertion loss and associated factors. 
     A quadrature hybrid power combiner  460  as a non-limiting example can be formed using different techniques and typically combines two, usually equal amplitude, quadrature-phased input signals into a single output signal. The combiner could use lumped element circuits, strip line circuits, or other circuits. The strip line circuits can be used in those applications requiring low loss or high power or both. Typically, a fundamental circuit element is a 3 dB quarter-wave coupler and formed as a four port network. The signal applied to a first port could be split equally between a second and third port with one of the outputs having a relative 90-degree phase shift. When the second and third ports are terminated into matching impedances, the signal applied to the first port is typically transmitted to a load connected to the second and third ports such that a fourth port receives negligible power and is “isolated.” An impedance mismatch at the second port could reflect some signal power back from the second port to be divided proportionally between the first and fourth ports. It is also possible to vary the relative input/output phasing even though the relationship between the output ports is maintained at 90 degrees. It may be possible to form a lumped element construction with one or more toroidal cores. Typically in a lumped element design, the insertion loss is related to the Q values of different components used in the network. In a strip line component, however, the insertion loss can result from the resistance of conductors and a mismatch loss at input/output ports and directivity loss. Thicker conductors could reduce some of that loss. 
     The I/Q modulation and power amplification circuit  400  shown in  FIG. 7  overcomes the technical drawbacks and problems associated with the type of circuit  300  shown in  FIG. 6  in which only one power amplifier circuit  350  is used after power combining, especially with power amplifier designs for GSM/GPRS/EDGE systems to achieve both GMSK and 8 PSK. Different RF transceiver systems have different transceiver architectures for digital frequency and phase modulations with IQ modulation. 
     The I/Q modulation and power amplification circuit  400  of  FIG. 7  with respective power amplifier circuits  450   a ,  450   b  in each of I and Q circuits  402 ,  404  allows greater control over any power amplifier driver and/or power amplifier biasing, even when using either open loop systems or larger or smaller closed loop systems. Controllers  480   a ,  480   b  (or one controller) are operative with the respective power amplifier circuit  450   a ,  450   b  and controls gain and other factors. The controllers  480   a ,  480   b  can be open loop or closed loop control (as shown by the dashed feedback line in each circuit). The I/Q modulation and power amplification circuit  400  shown in  FIG. 7  unifies the IQ modulation scheme with linear/higher efficiency/higher power requirements of power amplifier designs such that different types of digital modulations, for example, AM, FM and PM can be fulfilled. Also, the two respective power amplifier circuits  450   a ,  450   b  shown in  FIG. 7  can be calibrated to achieve high linear/efficiency/power amplifier design with low harmonics and less sensitivity to antenna loading. 
     In one non-limiting aspect, the power combiner  460  is operative as a 3 dB quadrature hybrid combiner as noted before. With this circuit design as described, two power amplifier circuits  450   a ,  450   b  could be used with only 30 dBm (1 watt) output power to achieve 33 dBm. The loss due to the power combiner  460  could be about 0.2 to about 0.3 dB, which could handled using a sharp low pass filter  462  to force down the third harmonics of the power amplifier. Thus, it is possible that the power amplifier circuits  450   a ,  450   b  with 30 dBm output can be established to achieve 33 dBm output. Typically, using the 3 dB quadrature hybrid power combiner  460 , it is possible to isolate the antenna matching from the power amplifier matching to obtain better transmission radiated power (TRP). As a result, the antenna design does not require more than one feed port to incorporate the power combiner as described. 
     It should be understood that the quadrature hybrid power combiner  460  can be tolerable to the mismatch of an antenna load impedance. Also, the quadrature hybrid gives greater reflectivity for phase and frequency modulation. Thus, efficient amplitude modulation can occur by changing the bias of the power amplifier circuits  450   a ,  450   b  for each of the In-phase and Quadrature circuits  402 ,  404  and give greater flexibility in circuit function. 
       FIG. 7A  illustrates a graph showing an example of the cancellation of some even order harmonics using the circuit of  FIG. 7 . 
     Some mobile wireless communications devices incorporate various antenna designs that include antenna contacts such as shown in  FIGS. 8 and 9 . These antenna contacts typically connect between an antenna carried inside the mobile wireless communications device such as shown in  FIGS. 1-3  and a circuit board carrying RF circuitry, such as a transceiver. An equivalent schematic circuit diagram for the antenna contact  500  of  FIGS. 8 and 9  and an associated antenna is shown in  FIG. 10  in which the antenna  502  is illustrated. This antenna  502  includes a contact point (c)  504  connecting the antenna contact and at an antenna flex section  506  that extends from the contact point (c)  504  to the point where the antenna contact connects, and an extended flex section as an RF stub  508 . 
     As illustrated, the antenna contact  500  is configured to act like a spring such as shown in the examples of  FIGS. 9 and 10  (configured similar to an elongated clip or hairpin with upper and lower or top and bottom legs) and having an inductance L, based on its configuration and its contact to the RF stub and flex and to a contact on the printed circuit board  520 . Both  FIGS. 9 and 10  show how the antenna contact  500  forms a spring type mechanism in which the lower section or leg  530  forms a board contact that could be soldered or attached by other techniques to the printed circuit board  520 , for example, an antenna board as in  FIG. 10 . The upper section or leg  532  of the antenna contact is a biased spring section forming an upper leg engages an antenna at its contact point  504 , including any necessary feed lines or other contact points or connections. 
       FIG. 9  shows an additional contact section  534  that slides on the upper spring biased section or leg  532  to form a section that engages at the contact point the RF stub as explained before. This contact section  534  includes an upper contact member  536  shaped in an inverted U for making contact to the antenna near the RF stub at the contact point in one non-limiting example. The antenna contact  500  in  FIG. 8  could have a similar additional upper contact member  534  slid thereon. 
     One drawback of such antenna contact designs as shown in  FIGS. 8 and 9  and the equivalent schematic circuit of  FIG. 10  is that these antenna contacts as circuits do not provide adequate RF performance because of the long physical length that creates a higher radio frequency (RF) inductance. The RF performance varies significantly because of the design variation in antenna contact design. Also, the spring effect of these types of antenna contacts often is lost after being depressed even one time. This type of antenna contact is not as strong as desirable and does not adequately secure to an antenna after the mobile wireless communications device has been dropped several times, thus, creating reliability issues such as caused from weak solder joints engaging the antenna contact, for example, to the circuit board. 
       FIGS. 11-14  show an antenna contact  600  in accordance with a non-limiting aspect that offers better RF performance by significantly reducing any antenna contact length and providing parallel inductances as shown in the equivalent schematic circuit diagram of  FIG. 13 . This antenna contact  600  has similar functional components as in that shown in  FIGS. 8-10  but with enhanced performance resulting from better design. As shown in the schematic circuit diagram of  FIG. 13 , basic components of the antenna contact  600  include the extended flex portion as the RF stub  608 , the contact point  604 , the antenna flex  606  and other portions forming the antenna  602  and operating through RF components on the circuit board  620  such as a transceiver circuit. The equivalent inductance Le in  FIG. 13  is significantly reduced as compared with the single higher inductance of L shown in the antenna contact and associated antenna schematic circuit of  FIG. 8 . 
       FIGS. 11 ,  12  and  14  are fragmentary and partial isometric views of the antenna contact  600  and showing the basic configuration in  FIG. 12  with a portion of the antenna flex  606  and the contact point  604  and REF stub  608 . Relative dimensions are shown in the equivalent schematic circuit of  FIGS. 13 and 14  to give an idea of the resulting improvement in performance. 
     This configuration as shown in  FIGS. 11-14  provides consistent physical contact with the antenna flex  606  and REF stub  608  ( FIG. 11 ). To reduce the variation of the contact point C  604  and the extended antenna flex  606  and the RF stub  608 , a core shield EMI material  650  as an RF filter is added on the antenna flex at the contact point and engages the REF stub  608  and provides secure contact and low RF inductance and variation. As illustrated, to strengthen the resulting biasing of the antenna contact configuration, the antenna contact  600  includes a lower leg  630  at the upper spring biased section or upper leg  632  is formed to have increased mechanical support resulting from an inverted V-shaped configuration forming P 1  and P 2  for that upper section or upper leg  632  along with a horizontally extending slide landing element  670  P 3 . To avoid potential solder wicking during a solder reflow process when the antenna contact  600  is soldered onto a circuit board such as a main circuit board or antenna board, the edges  672  for the slide landing element P 3   670  are elevated from contact with P 4   630  as the lower section that contacts the printed circuit board and forms a concave shape or U-shaped bend while still maintaining physical and electrical contact with the lower leg  630  P 4 . Thus, the antenna contact still has a configuration similar to a C-clip, but with greater efficiency of design. This improved antenna contact  600  as described and shown in  FIGS. 11-13  provides strong and secure physical contact to improve the reliability of a drop test while offering good and consistent radio frequency (RF) performance. 
     The EMI material forming the filter  650  as shown in  FIGS. 12 and 14  can be a conductive foam glued to the antenna flex as the RF stub  608 , such as a Gore-Shield® EMI material as the GS8000 EMI shielding gasket, This type of material provides excellent conformability and excellent cavity-to-cavity EMI shielding and conductivity at low compressive forces. 
     This type of material can be supplied as a precision die-cut part on rolls and can be formed as a foil-backed, nickel-plated base polymer with an electrically conductive and pressure-sensitive adhesive. No curing is required. 
     
       
         
           
               
            
               
                   
               
               
                 GS8000 Nominal Properties 
               
            
           
           
               
               
               
            
               
                 Property 
                 Nominal Value 
                 Test Method 
               
               
                   
               
               
                 Composite thickness 
                 1.62 ± 0.25 mm 
                 Measured 
               
               
                 Die-cut thickness 
                 1.0 mm 1   
                 Optically 
               
               
                 Liner 
                 0.51 mm Polyester 
                 N/A 
               
               
                 Recommended compression 
                 0.3 to 0.5 mm 
                 N/A 
               
               
                 stop 
                 (0.4 mm ideal) 
               
               
                 Pressure to compress to 
                 3.5 kg/cm 2   
                 EM2WIIN 
               
               
                 0.4 mm 
                 (50 psi) 
                 T-1055 2,3   
               
               
                 DC resistance at 0.4 mm 
                 6 mΩ 
                 EM2WIIN 
               
               
                   
                   
                 T-1055 2,3   
               
               
                 Volume resistivity at 0.4 mm 
                 0.03 Ω-cm 
                 Modified 
               
               
                   
                   
                 ASTM-D2739 
               
               
                 Shielding effectiveness at 
                 &gt;80 dB 
                 Modified 
               
               
                 0.4 mm (0.1 to 3 GHz) 
                   
                 ARP-1705 4   
               
               
                   
               
            
           
         
       
     
     An example of relative dimensions for the antenna contact  600  is shown in  FIG. 14 . “X” could be about 4.2 mm. “Y” could be about 1.6 mm. “Z” could be about 1.5 mm. 
     This application is related to copending patent applications entitled, “MOBILE WIRELESS COMMUNICATIONS DEVICE WITH SEPARATE IN-PHASE AND QUADRATURE POWER AMPLIFICATION,” and “MOBILE WIRELESS COMMUNICATIONS DEVICE WITH ANTENNA CONTACT HAVING REDUCED RF INDUCTANCE,” which are filed on the same date and by the same assignee and inventors, the disclosures which are hereby incorporated by reference. 
     Many modifications and other embodiments will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that various modifications and embodiments are intended to be included within the scope of the appended claims.