PATENT DOCUMENT

Publication Number: US-7818029-B2
Application Number: US-78660607-A
Country: US
Kind Code: B2

Title: Wireless communications circuitry with antenna sharing capabilities for handheld electronic devices

Abstract:
Handheld electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may have first and second transceiver circuits that operate in the same radio-frequency band using different communications protocols. The wireless communications circuitry may have a configurable radio-frequency combiner and divider circuit that is coupled between an antenna and the first and second transceiver circuits. The combiner and divider circuit can be configured to support simultaneous use of the antenna by the first and second transceiver circuits. When simultaneous use is not required, the combiner and divider circuit can be used by either the first transceiver circuit or the second transceiver circuit.

Claims:
1. A wireless handheld electronic wireless device comprising:
 storage that stores data; processing circuitry coupled to the storage that generates data for wireless transmission and that processes wirelessly received data; and 
 wireless communications circuitry, wherein the wireless communications circuitry comprises: 
 transceiver circuitry comprising a first transceiver circuit and a second transceiver circuit, wherein the first and second transceiver circuits communicate using different communications protocols and a common radio-frequency frequency band; 
 an antenna that handles radio-frequency signals in the common radio-frequency frequency band; and 
 a radio-frequency combiner and divider circuit comprising a first terminal coupled to the antenna, 
 second and third terminals coupled respectively to the first transceiver circuit and the second transceiver circuit, a first path between the first terminal and the second terminal, wherein the first path has a first switch, a second path between the first terminal and the third terminal, wherein the second path has a second switch, and a third path between the second and third terminals, wherein the third path has a third switch that is operable in an open position that opens the third path and a closed position that closes the third path, 
 wherein when the wireless communications circuitry is operated in a first mode the radio-frequency signals are simultaneously conveyed between the first terminal and both the second and third terminals over the first and second paths. 
 
     
     
       2. The wireless handheld electronic wireless device defined in  claim 1  wherein the first transceiver circuit comprises a wireless local area network (WLAN) transceiver circuit. 
     
     
       3. The wireless handheld electronic wireless device defined in  claim 1  wherein the second transceiver circuit comprises a Bluetooth transceiver circuit. 
     
     
       4. The wireless handheld electronic wireless device defined in  claim 1  wherein the first transceiver circuit comprises a wireless local area network (WLAN) transceiver circuit and the second transceiver circuit comprises a Bluetooth transceiver circuit. 
     
     
       5. The wireless handheld electronic wireless device defined in  claim 1  further comprising:
 a first amplifier that amplifies radio-frequency signals transmitted from the first transceiver circuit; 
 a second amplifier that amplifies radio-frequency signals before they are received by the first transceiver circuit; and 
 a fourth switch coupled between the second terminal and the first transceiver circuit, wherein the fourth switch has a first position in which radio-frequency signals are received from the first amplifier and provided to the second terminal and a second position in which radio-frequency signals are received from the second terminal and provided to the second amplifier. 
 
     
     
       6. Wireless communications circuitry comprising:
 a first wireless transceiver circuit that transmits and receives according to a first communications protocol in a given radio-frequency communications frequency band; 
 a second wireless transceiver circuit that transmits and receives according to a second communications protocol in the given radio-frequency communications frequency band, wherein the first and second communications protocols are different; 
 an antenna; 
 a radio-frequency combiner and divider circuit having first, second, and third switches that are responsive to control signals, wherein the combiner and divider circuit is coupled between the antenna and the first and second wireless transceiver circuits, wherein the wireless communications circuitry is operative in at least first, second, and third modes of operation, wherein:
 in the first mode of operation, the first wireless transceiver circuit is active and the second wireless transceiver circuit is inactive and radio-frequency signals are conveyed exclusively between the antenna and the first wireless transceiver circuit through the combiner and divider circuit; 
 in the second mode of operation, the first and second wireless transceiver circuits are both active and radio-frequency signals are simultaneously transmitted from both the first and second wireless transceiver circuits through the combiner and divider circuit and through the antenna; and 
 in the third mode of operation, the first wireless transceiver circuit is inactive and the second wireless transceiver is active and radio-frequency signals are conveyed exclusively between the antenna and the second wireless transceiver circuit through the combiner and divider circuit. 
 
 
     
     
       7. The wireless communications circuitry defined in  claim 6  wherein the combiner and divider circuit comprises a first diode in the first switch, a second diode in the second switch, and a third diode in the third switch. 
     
     
       8. The wireless communications circuitry defined in  claim 6  wherein the first switch comprises a diode, wherein the combiner and divider circuit comprises at least a first control terminal, and wherein when the first control terminal is taken high by application of the control signals the diode is forward biased and the first switch is placed in a closed position. 
     
     
       9. The wireless communications circuitry defined in  claim 6  wherein the combiner and divider circuit comprises at least first and second control terminals, wherein the first switch comprises a first diode, wherein the second switch comprises a second diode, wherein when the first control terminal is taken high by application of the control signals the first diode is forward biased and the first switch is placed in a closed position, wherein when the first control terminal is taken low by application of the control signals the first diode is not forward biased and the first switch is placed in an open position, wherein when the second control terminal is taken high by application of the control signals the second diode is forward biased and the second switch is placed in a closed position, and wherein when the second control terminal is taken low by application of the control signals the second diode is not forward biased and the second switch is placed in an open position. 
     
     
       10. The wireless communications circuitry defined in  claim 6  wherein the combiner and divider circuit comprises at least first and second control terminals, wherein the first switch comprises a first diode, wherein the second switch comprises a second diode, wherein the third switch comprises a third diode, and wherein when the first control terminal is taken high by application of the control signals the first diode is forward biased and the first switch is placed in a closed position, wherein when the first control terminal is taken low by application of the control signals the first diode is not forward biased and the first switch is placed in an open position, wherein when the second control terminal is taken high by application of the control signals the second diode is forward biased and the second switch is placed in a closed position, wherein when the second control terminal is taken low by application of the control signals the second diode is not forward biased and the second switch is placed in an open position, and wherein when the first control terminal and second control terminal are taken high by application of the control signals the third diode is forward biased and the third switch is placed in a closed position. 
     
     
       11. A method for using wireless communications circuitry in a handheld wireless device that includes a radio-frequency combiner and divider circuit having a first terminal coupled to an antenna, second and third terminals coupled respectively to a first transceiver circuit and a second transceiver circuit, a first path between the first terminal and the second terminal, wherein the first path has a first switch, a second path between the first terminal and the third terminal, wherein the second path has a second switch, and a third path between the second and third terminals, and wherein the third path has a third switch, comprising:
 storing data in storage on the portable wireless device; 
 with processing circuitry that is coupled to the storage, generating data for wireless transmission and processing wirelessly received data; 
 with the antenna and the first transceiver circuit in the wireless communications circuitry, communicating wirelessly in a communications frequency band according to a first communications protocol; 
 with the antenna and the second transceiver circuit in the wireless communications circuitry, communicating wirelessly in the communications frequency band according to a second communications protocol that is different than the first communications protocol; 
 when it is desired to simultaneously handle data with both the first and the second transceiver circuits, closing the first, second, and third switches and conveying radio-frequency signals between the antenna and both the first and second transceiver circuits through the radio-frequency combiner and divider circuit; 
 when it is desired to handle data with the first transceiver circuit while the second transceiver circuit is inactive, closing the first switch, opening the second and third switches, and conveying radio-frequency signals exclusively between the antenna and the first transceiver circuit; and 
 when it is desired to handle data with the second transceiver circuit while the first transceiver circuit is inactive, closing the second switch, opening the first and third switches, and conveying radio-frequency signals exclusively between the antenna and the second transceiver circuit. 
 
     
     
       12. The method defined in  claim 11  further comprising:
 when it is desired to transmit and receive wireless data through the antenna with the first transceiver circuit, placing the wireless communications circuitry in a wireless local area network transmit mode of operation in which the first transceiver circuit is active and transmits and receives wireless local area network radio-frequency signals through the antenna. 
 
     
     
       13. The method defined in  claim 11  further comprising:
 when it is desired to transmit and receive wireless data through the antenna with only the second transceiver circuit, placing the wireless communications circuitry in a mode of operation in which the first transceiver circuit is inactive and the second transceiver circuit is active and transmitting and receiving Bluetooth radio-frequency signals through the antenna. 
 
     
     
       14. The method defined in  claim 11  wherein the first path has a radio-frequency impedance, the second path has a radio-frequency impedance, and the third path has a radio-frequency impedance, wherein the first radio-frequency impedance and the second radio-frequency impedance are equal, and wherein the third radio-frequency is larger than the first radio-frequency impedance, the method further comprising:
 when it is desired to transmit wireless data through the antenna from the first transceiver circuit, activating the first transceiver circuit so that the first transceiver circuit transmits radio-frequency signals through the antenna; and 
 when it is desired to transmit wireless data through the antenna from the second transceiver circuit, activating the second transceiver circuit so that the second transceiver circuit transmits radio-frequency signals through the antenna. 
 
     
     
       15. The method defined in  claim 11  wherein the first path has a radio-frequency impedance, the second path has a radio-frequency impedance, and the third path has a radio-frequency impedance, wherein the first radio-frequency impedance and the second radio-frequency impedance are equal, and wherein the third radio-frequency is larger than the first radio-frequency impedance, the method further comprising:
 when it is desired to transmit wireless data through the antenna from both the first transceiver circuit and the second transceiver circuit simultaneously, activating the first and second transceiver circuits so that the first and second transceiver circuits transmit radio-frequency signals through the antenna. 
 
     
     
       16. Wireless communications circuitry comprising:
 a first wireless transceiver circuit that transmits and receives according to a first communications protocol in a 2.4 GHz radio-frequency communications band; 
 a second wireless transceiver circuit that transmits and receives according to a second communications protocol in the 2.4 GHz radio-frequency communications band, wherein the first and second communications protocols are different; 
 an antenna that operates in the 2.4 GHz radio-frequency communications band; 
 a radio-frequency combiner and divider circuit comprising a first terminal coupled to the antenna, second and third terminals coupled respectively to the first wireless transceiver circuit and the second wireless transceiver circuit, a first path between the first terminal and the second terminal, wherein the first path has a first switch, a second path between the first terminal and the third terminal, wherein the second path has a second switch, and a third path between the second and third terminals, wherein the third path has a third switch, wherein the radio-frequency combiner and divider circuit is responsive to control signals and routes radio-frequency signals to and from the antenna, wherein the radio-frequency combiner and divider circuit is operative in at least first and second modes, and wherein:
 in the first mode of operation, the first wireless transceiver circuit is active and the second wireless transceiver circuit is inactive and radio-frequency signals are conveyed exclusively between the antenna and the first wireless transceiver circuit through the combiner and divider circuit; and 
 in the second mode of operation, the first and second wireless transceiver circuits are both active and radio-frequency signals are simultaneously transmitted from both the first and second wireless transceiver circuits through the combiner and divider circuit and through the antenna. 
 
 
     
     
       17. The wireless communications circuitry defined in  claim 16  further comprising a power amplifier that amplifies signals that are transmitted by the first wireless transceiver circuit during the first mode of operation, wherein the wireless communications circuitry is operative in a third mode of operation and wherein in the third mode of operation the first wireless transceiver circuit is inactive and the second wireless transceiver is active and radio-frequency signals are conveyed exclusively between the antenna and the second wireless transceiver circuit through the combiner and divider circuit. 
     
     
       18. The wireless communications circuitry defined in  claim 16  further comprising a power amplifier that amplifies the signals that are transmitted by the first wireless transceiver circuit in the first mode of operation, wherein the wireless communications circuitry is operative in at least a third mode, wherein in the third mode of operation the first wireless transceiver circuit is inactive and the second wireless transceiver is active, and wherein the first wireless transceiver comprises a wireless local area network transceiver circuit. 
     
     
       19. The wireless communications circuitry defined in  claim 16  wherein the first path has a first impedance in the 2.4 GHz radio-frequency communications band, wherein the second path has a second impedance in the 2.4 GHz radio-frequency communications band, and wherein the first impedance is equal to the second impedance. 
     
     
       20. The wireless communications circuitry defined in  claim 16  wherein the first path has a first impedance in the 2.4 GHz radio-frequency communications band, wherein the second path has a second impedance in the 2.4 GHz radio-frequency communications band, wherein the third path has a third impedance in the 2.4 GHz radio-frequency communications band, wherein the first impedance is equal to the second impedance, wherein the third impedance is larger than the first impedance, and wherein the first and second paths each comprise an inductor. 
     
     
       21. A method for controlling a wireless handheld electronic device with wireless communications circuitry having a first wireless transceiver, a second wireless transceiver, an antenna, and a radio-frequency combiner and divider circuit having a first terminal coupled to the antenna, second and third terminals coupled respectively to the first transceiver circuit and the second transceiver circuit, a first path between the first terminal and the second terminal, wherein the first path has a first switch, a second path between the first terminal and the third terminal, wherein the second path has a second switch, and a third path between the second and third terminals, wherein the third path has a third switch that is operable in an open position that opens the third path and a closed position that closes the third path, the method comprising:
 when it is desired to convey wireless data through the antenna using the first wireless transceiver while the second wireless transceiver is inactive, placing the wireless communications circuitry in a first mode of operation in which the first wireless transceiver circuit is active and handles radio-frequency signals passing through the radio-frequency combiner and divider circuit; 
 when it is desired to convey wireless data through the antenna using the second wireless transceiver while the first wireless transceiver is inactive, placing the wireless communications circuitry in a second mode of operation in which the second wireless transceiver circuit is active and handles radio-frequency signals passing through the radio-frequency combiner and divider circuit; 
 when it is desired to convey wireless data through the antenna using both the first and second wireless transceivers simultaneously, placing the wireless communications circuitry in a third mode of operation in which the first and second wireless transceiver circuits are active and handle radio-frequency signals passing through the radio-frequency combiner and divider circuit; and 
 in the third mode of operation, closing the third switch. 
 
     
     
       22. The method defined in  claim 21 , wherein the first wireless transceiver circuit and the second wireless transceiver circuit operate according to different communications protocols, the method further comprising:
 amplifying the transmitted radio-frequency signals from the first wireless transceiver circuit through a power amplifier when the wireless communications circuitry is in the first mode. 
 
     
     
       23. The method defined in  claim 21 , the method further comprising:
 when in the first mode, transmitting and receiving wireless data with the first wireless transceiver circuit according to a wireless local area network protocol; and 
 when in the second mode of operation, transmitting and wireless data with the second wireless transceiver circuit according to a protocol that is different than the wireless local area network protocol. 
 
     
     
       24. The method defined in  claim 21  further comprising:
 when it is desired to use both the first and second wireless transceiver circuits simultaneously in the third mode of operation, closing the first, second, and third switches. 
 
     
     
       25. The method defined in  claim 21  further comprising:
 in the first mode of operation, closing the first switch and opening the second and third switches; 
 in the second mode of operation, closing the second switch and opening the first and second switches; and 
 in the third mode of operation, closing the first and second switches. 
 
     
     
       26. Wireless communications circuitry comprising:
 transceiver circuitry comprising a first transceiver circuit and a second transceiver circuit, wherein the first and second transceiver circuits communicate using different communications protocols and a common radio-frequency frequency band; 
 an antenna that handles radio-frequency signals in the common radio-frequency frequency band; and 
 a radio-frequency combiner and divider circuit comprising a first terminal coupled to the antenna, second and third terminals coupled respectively to the first transceiver circuit and the second transceiver circuit, a first path between the first terminal and the second terminal, wherein the first path has a first switch, a second path between the first terminal and the third terminal, wherein the second path has a second switch, and a third path between the second and third terminals, wherein the third path has a third switch that is operable in an open position that opens the third path and a closed position that closes the third path, and wherein when the wireless communications circuitry is operated in a first mode, the radio-frequency signals are simultaneously conveyed between the first and second terminals and between the first and third terminals. 
 
     
     
       27. The wireless communications circuitry defined in  claim 26 , further comprising a fourth switch that is connected between the second terminal and the first transceiver circuit and that has at least first and second positions, wherein when the wireless communications circuitry is operated in the first mode and the fourth switch is placed in the first position, radio-frequency signals are transmitted to the antenna from the first transceiver circuit while the second transceiver circuit is active and when the wireless communications circuitry is operated in the first mode and the fourth switch is placed in the second position, radio-frequency signals are received from the antenna by the first transceiver circuit while the second transceiver circuit is active. 
     
     
       28. The wireless communications circuitry defined in  claim 26 , wherein the combiner and divider circuit comprises a control signal path having three lines that receives three control signals, wherein when it is desired to operate the wireless communications circuitry in the first mode, the control signals direct the first switch to operate in a closed position, the control signals direct the second switch to operate in a closed position, and the control signals direct the third switch to operate in a closed position. 
     
     
       29. The wireless communications circuitry defined in  claim 26 , wherein the combiner and divider circuit comprises a control signal path having at least two lines, wherein the control signal path receives control signals and wherein when it is desired to operate the wireless communications circuitry in a second mode in which the first transceiver is active and the second transceiver is inactive, the control signals direct the first switch to operate in a closed position, the control signals direct the second switch to operate in an open position, and the control signals direct the third switch to operate in an open position. 
     
     
       30. The wireless communications circuitry defined in  claim 26 , wherein the combiner and divider circuit comprises a control signal path that receives control signals and wherein:
 when it is desired to operate the wireless communications circuitry in a second mode in which the first transceiver is active and the second transceiver is inactive, the control signals direct the first switch to operate in a closed position, the control signals direct the second switch to operate in an open position, and the control signals direct the third switch to operate in an open position; and 
 when it is desired to operate the wireless communications circuitry in a third mode in which the first transceiver is inactive and the second transceiver is active, the control signals direct the first switch to operate in an open position, the control signals direct the second switch to operate in a closed position, and the control signals direct the third switch to operate in an open position.

Description:
BACKGROUND 
     This invention relates generally to wireless communications circuitry, and more particularly, to wireless communications circuitry with that supports antenna sharing on handheld electronic devices. 
     Handheld electronic-devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. 
     Due in part to their mobile nature, handheld electronic devices are often provided with wireless communications capabilities. Handheld electronic devices may use long-range wireless communications to communicate with wireless base stations. For example, cellular telephones may communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz (e.g., the main Global System for Mobile Communications or GSM cellular telephone bands). Handheld electronic devices may also use short-range wireless communications links. For example, handheld electronic devices may communicate using the WiFi® (IEEE 802.11) band at 2.4 GHz and the Bluetooth® band at 2.4 GHz. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to reduce the number of components that are used. For example, in some wireless designs a single antenna is shared by two transceivers. Because there is only a single antenna with this type of approach, device size is minimized. 
     It is not always desirable to share an antenna in a wireless device. In conventional shared antenna arrangements with two transceivers operating on a shared communications frequency, the two transceivers compete with each other for use of the antenna. If, for example, data is being received by one of the transceivers, data cannot be received by the other transceiver. This may lead to dropped data packets and service interruptions. 
     It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless handheld electronic devices. 
     SUMMARY 
     In accordance with an embodiment of the present invention, a handheld electronic device with wireless communications circuitry is provided. The handheld electronic device may have cellular telephone, music player, or handheld computer functionality. The wireless communications circuitry may have multiple transceivers that share an antenna. 
     The wireless communications circuitry may have first and second transceiver circuits that operate in a common frequency band using different communications protocols. The first transceiver circuit may be, for example, a wireless local area network (WLAN) transceiver integrated circuit that handles IEEE 802.11 traffic at 2.4 GHz. The second transceiver circuit may be a Bluetooth transceiver circuit that handles Bluetooth data at 2.4 GHz. 
     The wireless communications circuitry may have a radio-frequency combiner and divider circuit that is coupled between and antenna and the first and second transceiver circuits. The combiner and divider circuit may be configured to support simultaneous use of both the first and second transceiver circuits or can be configured to support use of only the first or only the second transceiver circuit. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative handheld electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative handheld electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 3  is a schematic diagram of conventional wireless communications circuitry for a wireless electronic device. 
         FIG. 4  is a schematic diagram showing how a combiner and divider circuit may be used to allow an antenna to be shared by multiple transceivers in a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 5  is a schematic diagram of an illustrative combining and divider circuit based on a configurable splitter that may be used in wireless communications circuitry for a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 6  is a schematic diagram of illustrative wireless communications circuitry containing a wireless local area network circuit and a Bluetooth circuit in accordance with an embodiment of the present invention. 
         FIG. 7  is a circuit diagram of illustrative configurable splitter circuitry that may be used in a combining and divider circuit in a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 8  is a table of illustrative settings and operating modes for a configurable splitter circuitry of the type shown in  FIG. 7  in accordance with an embodiment of the present invention. 
         FIG. 9  is a state diagram illustrating operating modes of wireless communications circuitry having a configurable splitter circuit in a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 10  is a circuit diagram of another illustrative configurable splitter circuit that may be used in a combining and divider circuit in a handheld electronic device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to wireless communications and more particularly, to wireless communications circuitry that supports antenna sharing in electronic devices such as portable electronic devices. 
     An illustrative portable electronic device in accordance with an embodiment of the present invention is shown in  FIG. 1 . Portable electronic devices such as illustrative portable electronic device  10  may be laptop computers or small portable computers such as those sometimes referred to as ultraportables. Portable electronic devices may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. 
     With one suitable arrangement, the portable electronic devices are handheld electronic devices. Space is at a premium in handheld electronics devices, so antenna-sharing arrangements for handheld electronic devices can be particularly advantageous. The use of handheld devices is therefore generally described herein as an example, although any suitable electronic device may be used with the wireless communications functions of the present invention, if desired. 
     Handheld devices may be, for example, cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, global positioning system (GPS) devices, and handheld gaming devices. The handheld devices of the invention may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid handheld devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a handheld device that receives email, supports mobile telephone calls, and supports web browsing. These are merely illustrative examples. Device  10  may be any suitable portable or handheld electronic device. 
     Device  10  includes housing  12  and includes at least one antenna for handling wireless communications. Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, wood, glass, ceramics, metal, or other suitable materials, or a combination of these materials. In some situations, case  12  may be a dielectric or other low-conductivity material, so that the operation of conductive antenna elements that are located in proximity to case  12  is not disrupted. In other situations, case  12  may be formed from metal elements. In scenarios in which case  12  is formed from metal elements, one or more of the metal elements may be used as part of the antenna(s) in device  10 . 
     Any suitable type of antenna may be used to support wireless communications in device  10 . Examples of suitable antenna types include antennas with resonating elements that are formed from a patch antenna structure, a planar inverted-F antenna structure, a helical antenna structure, etc. To minimize device volume, at least one of the antennas in device  10  may be shared between two transceiver circuits. 
     Handheld electronic device  10  may have input-output devices such as a display screen  16 , buttons such as button  23 , user input control devices  18  such as button  19 , and input-output components such as port  20  and input-output jack  21 . Display screen  16  may be, for example, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a plasma display, or multiple displays that use one or more different display technologies. As shown in the example of  FIG. 1 , display screens such as display screen  16  can be mounted on front face  22  of handheld electronic device  10 . If desired, displays such as display  16  can be mounted on the rear face of handheld electronic device  10 , on a side of device  10 , on a flip-up portion of device  10  that is attached to a main body portion of device  10  by a hinge (for example), or using any other suitable mounting arrangement. 
     A user of handheld device  10  may supply input commands using user input interface  18 . User input interface  18  may include buttons (e.g., alphanumeric keys, power on-off, power-on, power-off, and other specialized buttons, etc.), a touch pad, pointing stick, or other cursor control device, a touch screen (e.g., a touch screen implemented as part of screen  16 ), or any other suitable interface for controlling device  10 . Although shown schematically as being formed on the top face  22  of handheld electronic device  10  in the example of  FIG. 1 , user input interface  18  may generally be formed on any suitable portion of handheld electronic device  10 . For example, a button such as button  23  (which may be considered to be part of input interface  18 ) or other user interface control may be formed on the side of handheld electronic device  10 . Buttons and other user interface controls can also be located on the top face, rear face, or other portion of device  10 . If desired, device  10  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth remote control, etc.). 
     Handheld device  10  may have ports such as bus connector  20  and jack  21  that allow device  10  to interface with external components. Typical ports include power jacks to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data ports to exchange data with external components such as a personal computer or peripheral, audio-visual jacks to drive headphones, a monitor, or other external audio-video equipment, etc. The functions of some or all of these devices and the internal circuitry of the handheld electronic device can be controlled using input interface  18 . 
     Components such as display  16  and user input interface  18  may cover most of the available surface area on the front face  22  of device  10  (as shown in the example of  FIG. 1 ) or may occupy only a small portion of the front face  22 . Because electronic components such as display  16  often contain large amounts of metal (e.g., as radio-frequency shielding), the location of these components relative to the antenna elements in device  10  should generally be taken into consideration. Suitably chosen locations for the antenna elements and electronic components of the device will allow the antenna of handheld electronic device  10  to function properly without being disrupted by the electronic components. 
     A schematic diagram of an embodiment of an illustrative handheld electronic device is shown in  FIG. 2 . Handheld device  10  may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a remote control, a game player, a global positioning system (GPS) device, a combination of such devices, or any other suitable portable electronic device. 
     As shown in  FIG. 2 , handheld device  10  may include storage  34 . Storage  34  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
     Processing circuitry  36  may be used to control the operation of device  10 . Processing circuitry  36  may be based on a processor such as a microprocessor and other suitable integrated circuits. With one suitable arrangement, processing circuitry  36  and storage  34  are used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. Processing circuitry  36  and storage  34  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using processing circuitry  36  and storage  34  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, etc.) 
     Input-output devices  38  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Display screen  16  and user input interface  18  of  FIG. 1  are examples of input-output devices  38 . 
     Input-output devices  38  can include user input-output devices  40  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . Display and audio devices  42  may include liquid-crystal display (LCD) screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Device  10  can communicate with external devices such as accessories  46  and computing equipment  48 , as shown by paths  50 . Paths  50  may include wired and wireless paths. Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content). In one illustrative scenario, paths  50  may include a wireless Bluetooth path that is used to support communications between a Bluetooth headset (one of accessories  46 ) and device  10  and a wireless local area network (WLAN) path (e.g., a WiFi path) that is used to support communications between device  10  and computing equipment  48 . 
     Computing equipment  48  may be any suitable computer. With one suitable arrangement, computing equipment  48  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  10 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another handheld electronic device  10 ), or any other suitable computing equipment. 
     Wireless communications devices  44  may be used to support local and remote wireless links. 
     Examples of local wireless links include WiFi and Bluetooth links and wireless universal serial bus (USB) links. Because wireless WiFi links are typically used to establish data links with local area networks, links such as WiFi links are sometimes referred to as WLAN links. The local wireless links may operate in any suitable frequency band. For example, WLAN links may operate at 2.4 GHz or 5.6 GHz (as examples), whereas Bluetooth links may operate at 2.4 GHz. The frequencies that are used to support these local links in device  10  may depend on the country in which device  10  is being deployed (e.g., to comply with local regulations), the available hardware of the WLAN or other equipment with which device  10  is connecting, and other factors. 
     With one suitable arrangement, which is sometimes described herein as an example, device  10  communicates using both the popular 2.4 GHz WiFi bands (802.11(b) and/or 802.11(g)) and the 2.4 GHz Bluetooth band using the same antenna. In this type of configuration, the antenna is designed to operate at a frequency of 2.4 GHz, so the antenna is suitable for use with the 2.4 GHz radio-frequency signals that are used in connection with both the WiFi and Bluetooth communications protocols. Circuitry  44  may include a configurable combiner and divider circuit that allows WiFi and Bluetooth signals to be handled simultaneously. 
     If desired, wireless communications devices  44  may include circuitry for communicating over remote communications links. Typical remote link communications frequency bands include the cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, the global positioning system (GPS) band at 1575 MHz, and data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System). In these illustrative remote communications links, data is transmitted over links  50  that are one or more miles long, whereas in short-range links  50 , a wireless signal is typically used to convey data over tens or hundreds of feet. 
     These are merely illustrative communications bands over which wireless devices  44  may operate. Additional local and remote communications bands are expected to be deployed in the future as new wireless services are made available. Wireless devices  44  may be configured to operate over any suitable band or bands to cover any existing or new services of interest. If desired, multiple antennas and/or a broadband antenna may be provided in wireless devices  44  to allow coverage of more bands. At least one of the antennas (e.g., an antenna used for WiFi and Bluetooth communications at a common communications band frequency of 2.4 GHz) may be shared, as this helps reduce the size of wireless communications circuitry  44  and therefore reduces the size of device  10 . 
     In conventional wireless electronic devices in which an antenna is shared between multiple communications bands, switching circuitry is used to switch between different transceiver modules, because simultaneous use of both modules is not supported. While this type of arrangement may be satisfactory in undemanding applications, a shared antenna arrangement that is based solely on conventional switch arrangements can be inadequate in many contemporary situations. 
     Conventional wireless communications circuitry that is based on a traditional shared-antenna architecture is shown in  FIG. 3 . Wireless communications circuitry  52  includes antenna  54 , which handles radio-frequency signals at a frequency of 2.4 GHz. Switch  56  selectively connects antenna  54  to switch port S 1 , S 2 , or S 3 . Ports Si and S 2  are connected to wireless local area network (WLAN) integrated circuit  58  by respective paths  66  and  68 . Port S 3  is connected to Bluetooth integrated circuit  66  by path  70 . Wireless local-area-network integrated circuit  58  includes a WiFi transceiver and control circuitry. Bluetooth integrated circuit  60  includes a Bluetooth transceiver and control circuitry. WLAN circuit  58  and Bluetooth circuit  60  communicate with each other using handshaking path  62 . Paths  72  and  74  are used to provide data and control signals to circuits  58  and  66 . 
     WLAN circuit  58  controls the state of switch  56  using control path  64 . When it is desired to transmit WLAN data, switch  56  is connected to position S 1 , so that data can be transmitted from WLAN integrated circuit  58  to antenna  54  over path  66 . Switch  56  is connected to position S 2  when it is desired to receive data with WLAN circuit  58 . In position S 2 , signals from antenna  54  are conveyed through switch  56  and over path  68  to WLAN circuit  58 . Switch  56  has a third position—S 3 —that is used when it is desired to transmit or receive Bluetooth signals. In transmit mode, Bluetooth signals are transmitted to antenna  54  via transmit/receive path  70  and switch  56 . In receive mode, Bluetooth signals that have been received by antenna  54  are conveyed to Bluetooth integrated circuit  60  by switch  56  and path  70 . 
     The conventional arrangement of  FIG. 3  allows antenna  54  to be shared. WiFi traffic is handled by WLAN circuit  58  and Bluetooth traffic is handled by Bluetooth circuit  60 . Switch  56  can be switched between WLAN circuit  58  and Bluetooth circuit  60 , so that circuit  58  and  60  are able to take turns using antenna  54 . Although WLAN circuit  58  and Bluetooth circuit  60  cannot be used at the same time, switch  56  can be switched quickly, so that circuits  58  and  60  are able to use antenna  54  in rapid succession. 
     Because switch  56  cannot be connected to both WLAN circuit  58  and Bluetooth circuit  60  at the same time, it is necessary to prioritize. Consider, as an example, the situation in which a user of communications circuitry  52  is browsing the internet using WLAN circuit  58 , while using Bluetooth connection  60  to control a wireless mouse. In this type of situation, circuits  58  and  60  can decide to favor the Bluetooth connection over the WiFi connection. Whenever it is desired to connect to both the WLAN circuit  58  and the Bluetooth circuit  60  at the same time, the Bluetooth circuit is favored. 
     With this type of prioritization scheme, the user of circuit  52  will be able to use the wireless mouse without noticeable interruption. However, because the Bluetooth connection is favored over the WLAN connection, WLAN data packets will occasionally be dropped. 
     For example, consider the situation in which Bluetooth activity arises while requested internet data is being transmitted to WLAN circuit  58 . To handle the Bluetooth activity, switch  56  will be connected to switch position S 3 . Bluetooth data has priority over WLAN data, so the fact that WLAN circuit  58  is in the midst of receiving internet data is immaterial and switch  56  is switched to position S 3  to ensure that the Bluetooth activity is handled properly. 
     Placing switch  56  in position S 3  allows Bluetooth circuit  60  to transmit and receive Bluetooth data as needed. However, setting switch  56  to position S 3  prevents WLAN circuit  58  from receiving the internet data that is being transmitted. As a result, some internet data packets will be at least temporarily lost. 
     Data interruptions such as these are unavoidable using the conventional wireless communications circuitry arrangement of  FIG. 3 , because it is not possible to set switch  56  to a position that allows simultaneous transmission or reception of WLAN and Bluetooth data. Although data interruptions such as these may be acceptable in noncritical applications, in some situations the impact of lost data may be severe. For example, a user might desire to use WLAN circuit  58  to support a voice-over-internet-protocol (VOIP) telephone call over the internet, while using a Bluetooth headset. In real-time audio applications such as these, a high quality connection is critical. Using conventional wireless communications circuit  52  of  FIG. 3  may cause the VOIP voice signal to break up due to lost data packets. 
     Wireless communications circuitry  76  in accordance with an illustrative embodiment of the present invention is shown in  FIG. 4 . As shown in  FIG. 4 , wireless communications circuitry  76  has an antenna  78 . A filter  80  and a direct current (DC) blocking capacitor (not shown) may be used to filter out spurious noise from received signals. Circuitry  76  may include transceivers  110  and  120 . Transceiver  110  may, as an example, be a wireless local area network (WLAN) circuit that handles IEEE 802.11 traffic, whereas transceiver  120  may, as an example, be a Bluetooth circuit. If desired, transceivers  110  and  120  may be associated with other types of data traffic. 
     Radio frequency combiner and divider circuit  125  (which is also sometimes referred to as a configurable radio-frequency coupler) may allow transceivers  110  and  120  to use antenna  78  simultaneously. Control signals may be applied to combiner and divider circuit  125  via control input  123 . Using control signals on path  123 , circuitry  125  may be placed in various operating modes. For example, circuitry  125  may be placed in a simultaneous operation mode. In this mode transceiver  110  and transceiver  120  may simultaneously transmit or receive data through antenna  78 . When transmitting data, combiner and divider circuit  125  serves to combine signals from transceiver  110  and  120  and to provide the resulting combined signals to antenna  78 . When receiving data, combiner and divider circuit  125  serves as a divider that separates incoming radio-frequency signals from antenna  78  into two paths—one destined for transceiver  110  and one destined for transceiver  120 . 
     When it is desired to use only one of transceivers  110  and  120 , combiner and divider circuit  125  can be configured to direct all incoming and outgoing traffic to the appropriate transceiver. For example, when transceiver  110  is active, control signals can be provided to circuit  125  on path  123  that direct the combiner and divider circuit to route signals exclusively between antenna  78  and transceiver  110 . Transceiver  110  can be used to transmit data or to receive data when circuit  125  has been configured in this way. 
     When configured for simultaneous use of both transceivers, combiner and divider circuit performs the functions of a 3 dB splitter. The loss on each channel in this mode is about 3 dB. When configured to route signals exclusively between antenna  78  and a given one of the transceivers, loss is reduced to about 1 dB. The ability to configure circuit  125  therefore allows the wireless transmit and receive capability of circuitry  76  to be improve by about 2 dB at those points in time when it is not necessary to support simultaneous operation of both transceivers. 
     Combiner and divider circuit  125  may be implemented using any suitable circuit architecture. With one suitable arrangement, which is shown in  FIG. 5  as an example, combiner and divider  125  may be based on a Wilkinson splitter architecture. As shown in  FIG. 5 , circuit  125  may have first path  129  and second path  131  which are connected to antenna  78 . Path  129  may be selectively connected to antenna  78  through its switch SW 1  and line  133 . Path  131  is connected to antenna  78  through its switch SW 2  and line  135 . Filtering circuitry such as filter  80  of  FIG. 4  is not shown in  FIG. 5  to avoid over-complicating the drawing. 
     As shown in the example of  FIG. 5 , first and second branches  129  and  131  may be configured so that at their operating frequency each has an impedance of about 70 ohms and a length of one quarter of a wavelength. In the present example, the operating frequency is about 2.4 GHz. 
     Third branch  137  of circuit  125  may be connected between nodes A and B. The total impedance of branch path  137  may be about 100 ohms (as an example). The 100 ohm impedance of path  137  may be constructed using a single 100 ohm load, multiple 50 ohm loads (as shown schematically by resistive loads  139  and  141  in  FIG. 5 ), a 25 ohm load and a 75 ohm load, etc. Switch SW 3  in path  137  may be used to control whether or not the path of branch  137  is open or closed. Switches SW 1  and SW 2  may be used to control whether or not signals are conveyed between antenna  78  and transceivers  110  and  120 , respectively. 
     Transceivers  110  and  120  may be connected to branch paths  129  and  131  via paths  127 . Paths  127  may have impedances of about 50 ohms (as an example). 
     Circuit  125  can operate in three modes. In a first mode of operation, switches SW 1 , SW 2 , and SW 3  may be closed. With SW 1  and SW 2  closed, incoming signals may be split into first and second paths. The first path may be used to direct incoming signals to transceiver  110 . The second path may be used to direct incoming signals to transceiver  120 . Because switch S 3  is on in this mode of operation, path  137  may be switched into use. The impedance of path  137  may create a network in which the three paths  129 ,  131 , and  137  collectively form a 3 dB splitter. 
     In a second mode of operation, switch SW 1  may be closed and switches SW 2  and SW 3  may be open. In this mode, path  129  may be switched into use. With switches SW 2  and SW 3  open, there is a slight impedance mismatch between 50 ohm transmission line paths such as paths  127  and the 70 ohm load of branch  129 . This impedance mismatch may lead to a signal loss of about 1 dB. Nevertheless, there can be an improvement of about 2 dB relative to a fixed 3 dB splitter configuration. This 2 dB improvement in signal strength can therefore make it advantageous to place circuit  125  in the second mode of operation whenever it is desired to transmit or receive radio-frequency signals exclusively through the first (upper branch) of circuit  125  (e.g., using transceiver  110  while transceiver  120  remains unused). 
     In a third mode of operation, switch SW 1  may be open, switch SW 2  may be closed, and switch SW 3  may be open. In this mode path  131  may be switched into use and signals may be conveyed between antenna  78  and transceiver  120  exclusively through path  131 . 
       FIG. 6  shows how wireless communications circuitry  76  may include a combiner and divider circuit. Circuitry  76  may include transceiver and control circuitry  108 . Transceiver and control circuitry  108  may contain two or more transceiver circuits such as wireless local-area-network (WLAN) circuit  110  and Bluetooth circuit  120 . For clarity, a two-transceiver-circuit embodiment is described herein. 
     WLAN transceiver circuit  110  may be, for example, an integrated circuit that handles IEEE 802.11(b) or 802.11(g) signals using WiFi transceiver  112  and control circuitry  114 . Bluetooth transceiver circuit  120  may be, for example, an integrated circuit that handles Bluetooth signals using Bluetooth transceiver  116  and control circuitry  118 . Circuits  110  and  120  may be provided as two separate integrated circuits that are mounted on a common circuit board, using a single integrated circuit, or using more than two integrated circuits. With one suitable arrangement, WLAN circuit  110  is an integrated circuit such as Part No. 88W8686 of Marvell Semiconductor, Inc. of Santa Clara, Calif. and Bluetooth circuit  120  is an integrated circuit such as a BlueCore4 device of CSR, Cambridge, England. Circuits  110  and  120  may communicate with each other over handshaking path  126 . 
     Each transceiver circuit may handle a different type of wireless data traffic. In the example of  FIG. 6 , WiFi traffic is handled using wireless local-area-network (WLAN) circuit  110  and Bluetooth traffic is handled using Bluetooth circuit  120 . Each of these circuits interfaces with antenna  78  and with circuitry on the handheld electronic device in which wireless communications circuitry  76  is being used. 
     Data and control paths  122  and  124  may be used to form communications paths between transceiver and control circuitry  108  and other circuitry on device  10  such as processing circuitry  36  of  FIG. 2 . Paths  122  and  124  may be used to support any suitable type of data communications. As an example, path  122  may be used to convey control and user data using the so-called secure digital input/output (SDIO) protocol. Paths  124  and  122  may be formed of any suitable number of conductive lines. In the example of FIG.  6 , path  122  has been formed from a six-line bus and path  124  has been formed from a four-line bus. This is merely illustrative. Paths such as paths  122  and  124  may be formed from single lines or using larger or smaller busses of multiple lines, if desired. 
     WLAN circuit  110  may transmit WLAN data wirelessly using data transmission path  98  and may receive WLAN data wirelessly using data reception path  96 . Transmitted data on path  98  may be amplified by power amplifier  88 . Corresponding amplified versions of the transmitted data signals on path  98  may be provided to switch SW over path  100 . To transmit data over antenna  78 , control signals may be issued on path  106  that direct switch SW to connect path  100  to path  83  (switch position A). Combiner and divider circuit  125  may be configured to electrically connect path  83  to path  81  and antenna  78  and to thereby allow transceiver circuit  110  to be used. Received data from antenna  78  may be routed to path  97  when switch SW has been placed in switch position B. This received data may be amplified by an optional amplifier  99  and provided to transceiver circuit  110  via path  96 . Switch SW may be formed using any suitable switching technology. For example, switch SW may be a single-pole double throw switch based on a field-effect transistors (FETs). 
     As shown in this example, switch SW and amplifiers  88  and  99  may be provided separate from transceiver circuit  110 . Similar switching circuitry and amplifier circuitry may be provided internally, as part of transceiver circuit  110 , if desired. In the  FIG. 6  example, transceiver circuit  120  contains internal switch and amplifier circuitry. This internal circuitry allows signals to be transmitted from transceiver circuit  120  to combiner and divider  125  over path  101  and allows signals from combiner and divider  125  to be conveyed to transceiver circuit  120 . The internal switch and amplifier circuitry of transceiver circuit  120  may, if desired, be provided using an external switch and amplifier arrangement as described in connection with transceiver circuit  110 . 
     The settings of switch SW and the comparable settings of the internal circuitry in transceiver circuit  120  determine whether paths  83  and  101  are being used to transmit data or are being used to receive data. Combiner and divider circuit  125  may also be configured appropriately. Any suitable control arrangement may be used to control the operation of combiner and divider circuit  125 . As shown in the example of  FIG. 6 , a two-line path  103  may be used to convey control signals to combiner and divider circuit  125  from transceiver and control circuitry  108  (e.g., from transceiver circuit  110 ). This is merely illustrative. For example, a control path having three lines and three control terminals may be used to convey the control signals if desired. 
     The operating mode of combiner and divider circuit  125  may be selected based on which transceiver circuits are active. When only transceiver circuit  110  is active, signal TRANS 1 _ACTIVE on path  103  may be high and signal TRANS 2 _ACTIVE on path  103  may be low. In this mode, combiner and divider circuit  125  may be configured to convey signals between transceiver circuit  110  and antenna  78  with only moderate losses (e.g., about 1 dB due to the impedance mismatch between branch  129  and surrounding 50 ohm transmission lines). When only transceiver circuit  120  is active, signal TRANS 2 _ACTIVE on path  103  may be high and signal TRANS 1 _ACTIVE on path  103  may be low. In this mode, combiner and divider circuit  125  may be configured to convey signals between transceiver circuit  120  and antenna  78  with only minimal losses (e.g., about 1 dB). If it is desired to operate transceivers  110  and  120  simultaneously, both signals TRANS 1 _ACTIVE and TRANS 2 _ACTIVE may be taken high, configuring circuit  125  as a 3 dB coupler. 
     An illustrative circuit that may be used for combiner and divider circuit  125  is shown in  FIG. 7 . Control signal TRANS 1 _ACTIVE may be applied to terminal  132 . Terminal  130  may receive control signal TRANS 2 _ACTIVE. Signals may be grounded at ground terminals  136 . 
     Blocking capacitor  128  may be used to help protect circuit  125  from the potentially harmful effects of electrostatic discharge (ESD). Inductor  134  may be used to establish DC ground at node  190 . An inductance value may be chosen for inductor  134  so that the impedance of inductor  134  is sufficiently large at the operating frequency of circuit  125  (e.g., 500 ohms at an operating frequency of 2.4 GHz) and only a negligible amount of radio-frequency signal is shunted to ground  136 . 
     Switch SW 1  of  FIG. 5  may be formed from inductor  134 , diode  144 , resistor  146  (e.g., a 1000 ohm resistor), and capacitor  148  (e.g., a 10 pF capacitor), as shown by dashed line  140  in  FIG. 7 . Switch SW 2  of  FIG. 5  may be formed by inductor  134 , diode  150 , resistor  160  (e.g., a 1000 ohm resistor), and capacitor  162  (e.g., a 10 pF capacitor), as shown by dotted line  138  in  FIG. 7 . Dashed-and-dotted line  142  shows how switch SW 3  of  FIG. 5  may be formed from diode  172 , inductor  176  (e.g., a 27 mH inductor), capacitor  178  (e.g., a 10 pF capacitor), transistor  186 , and resistor  188 . 
     Diodes such as diodes  144 ,  159 , and  172  may be diodes suitable for radio-frequency switching applications such as p-i-n diodes having low off capacitances. 
     When diode  144  is off, its resistance is high (e.g., greater than 100 kilo ohms) and its junction and parasitic capacitance is low, so that radio-frequency signals are blocked (i.e., switch SW 1  is open). When diode  144  is on, its resistance is negligible (e.g., about 3 ohms) and it allows radio-frequency signals to pass (i.e., switch SW 1  is closed). Capacitor  148  may serve as a low pass filter that prevents radio-frequency signals from reaching control terminal  132 . 
     When control terminal  132  is taken high by asserting the TRANS 1 _ACTIVE signal, current flows through resistor  146 , diode  144 , and inductor  134 . In this situation, diode  144  is forward biased and switch SW 1  is closed. When control terminal  132  is low, diode  144  is reverse biased (or at least not forward biased) and switch SW 1  is open. 
     Similarly, when control terminal  130  is taken high by asserting the TRANS 2 _ACTIVE signal, current flows through resistor  160 , diode  150 , and inductor  134 . In this situation, diode  150  is forward biased and switch SW 2  is closed. When control terminal  130  is low (i.e., TRANS 2 _ACTIVE has been deasserted), diode  150  is reverse biased (or at least not forward biased) and switch SW 2  is open. 
     Capacitor  168 , inductor  166 , and capacitor  170  may be used to form the 70 ohm impedance path for first branch  129  ( FIG. 5 ). Similarly, capacitor  169 , inductor  164 , and capacitor  171  may be used to form the 70 ohm impedance path for second branch  131 . Resistor  180  may be used to form a 100 ohm path for branch  137  of  FIG. 5 . 
     Inductor  176  may be used to provide a direct current (DC) path for current to ground  136  while forming an L-C circuit with capacitor  178  (e.g., a 10 pF capacitor) that prevents radio-frequency signals from being diverted into switch SW 3 . Transistor  186  may serve as an inverter that converts the signal TRANS 2 _ACTIVE on line  130  into NOT TRANS 2 _ACTIVE on node  192 . Resistor  188  may serve as a pull-down resistor. In the event that the transceiver circuitry in device  10  is powered down so that an unknown signal voltage appears on control lines such as TRANS 1 _ACTIVE and TRANS 2 _ACTIVE, resistor  188  may help to pull node  193  low and thereby prevent the TRANS 2 _ACTIVE line  130  from floating and placing switch SW 3  in an unknown state. 
     When signal TRANS 1 _ACTIVE is low, diode  172  is reverse biased (or at least not forward biased) and switch SW 3  is off. When signal TRANS 1 _ACTIVE is high and NOT TRANS 2 _ACTIVE is low, a current flows through resistor  146 , inductor  166 , diode  172 , inductor  176 , and transistor  186  to ground  136 , forward biasing diode  172  and turning switch SW 3  on. When switch SW 3  is on and current is flowing through diode  172 , capacitor  182  may serve to prevent DC current from flowing through diode  150  and erroneously turning diode  150  on. 
     Capacitors  174  and  184  may be used to protect transceivers  110  and  120  from damage due to DC currents. 
     A table illustrating the states of switches SW 1 , SW 2 , and SW 3  that may be produced as a result of various control signal states for TRANS 1 _ACTIVE and TRANS 2 _ACTIVE is shown in  FIG. 8 . As shown in  FIG. 8 , signals TRANS 1 _ACTIVE and TRANS 2 _ACTIVE can be either high (i.e., a logic one) or low (i.e., a logic zero). Switches SW 1 , SW 2 , and SW 3  can be either on (closed) or off (open). 
     As indicated by column  194 , when TRANS 1 _ACTIVE is high and TRANS 2 _ACTIVE is low, switch SW 1  is on (because diode  144  is forward biased), switch SW 2  is off (because diode  150  is not forward biased), and switch SW 3  is off (because node  192  (NOT TRANS 2 _ACTIVE) is effectively open circuit, preventing diode  172  from being forward biased). In this configuration, combiner and divider circuit  125  can be used to convey signals exclusively between antenna  78  and transceiver circuit  110 . 
     As indicated by column  196 , when TRANS 2 _ACTIVE is high and TRANS 1 _ACTIVE is low, switch SW 2  is on (because diode  150  is forward biased), switch SW 1  is off (because diode  144  is not forward biased), and switch SW 3  is off (because node  132  (TRANS 1 _ACTIVE) is low, preventing diode  172  from being forward biased. In this configuration, combiner and divider circuit  125  may convey radio-frequency signals exclusively between antenna  78  and transceiver circuit  120 . 
     When TRANS 1 _ACTIVE is high and TRANS 2 _ACTIVE is high, switch SW 1  is on (because diode  144  is forward biased), switch SW 2  is on (because diode  150  is forward biased), and switch SW 3  is on (because node  132  is high and node  192  is low, forward biasing diode  172 . 
     An illustrative state diagram illustrating modes in which device  10  and wireless communications circuitry  76  may operate is shown in  FIG. 9 . The embodiment of wireless communications circuitry  76  that is described in connection with the state diagram of  FIG. 9  may have a first transceiver such as transceiver circuit  110  that handles a first type of wireless communications (e.g., wireless local area network communications, also sometimes referred to as WiFi communications or IEEE 802.11 communications) and may have a second transceiver such as transceiver circuit  120  that is used to handle Bluetooth communications. This type of arrangement is merely illustrative. In general, wireless communications circuitry  76  and transceiver and control circuitry  108  can be used to support any suitable communications protocols. The use of WLAN and Bluetooth communications protocols is described as an example. 
     As shown in  FIG. 9 , wireless communications circuitry  76  and device  10  may operate in at least three states, state  212 , state  214 , and state  216 . 
     In state  214 , Bluetooth circuit  120  is active in Bluetooth TX or RX mode, whereas WLAN circuit  110  is inactive. The state of an internal switch in transceiver  120  may be used to determine whether circuit  120  is transmitting or receiving wireless Bluetooth signals. State  214  corresponds to column  196  in the table of  FIG. 8 . During state  214 , switch SW 2  is on and switches SW 1  and SW 3  are off, so that signals may be conveyed between antenna  78  and transceiver circuit  120  with relatively low losses (e.g., about 1 dB). 
     When it is desired to operate both transceiver circuits  110  and  120  simultaneously, control paths such as paths  122  and  124  of  FIG. 6  may be used to activate both circuits  110  and  120 , while path  103  ( FIG. 6 ) may be used to assert signal TRANS 1 _ACTIVE. The causes circuit  125  to transition from state  214  to state  212 , as indicated by line  208 . Circuit  125  can be returned to state  214  by deasserting signal TRANS 1 _ACTIVE, as indicated by line  210 . 
     In state  212 , both TRANS 1 _ACTIVE and TRANS 2 _ACTIVE high and switches SW 1 , SW 2 , and SW 3  are on (closed), as indicated by column  198  in the table of  FIG. 8 . In this mode of operation, signals may be conveyed between both circuits  110  and  120  and antenna  78 . There is a somewhat larger loss (e.g., about 3 dB) associated with using both transceiver circuits  110  and  120  simultaneously, but it is not necessary to drop transmitted data packets as it would be with the conventional antenna sharing arrangement described in connection with  FIG. 3 . The state of switch SW ( FIG. 6 ) and the state of the internal switching circuitry of transceiver circuit  120  may be used to determine whether circuits  110  and  120  are transmitting or receiving data. 
     When it is desired to use only transceiver circuit  110 , while deactivating transceiver circuit  120 , control paths  122  and  124  can be used to turn transceiver circuit  120  off, while maintaining transceiver circuit  110  in its on condition. Path  103  may be used to deassert signal TRANS 2 _ACTIVE. This places circuit  215  in state  216 , as indicated by line  200 . Circuit  215  can be returned to state  212  by asserting signal TRANS 2 _ACTIVE, as indicated by line  202 . 
     When in state  216 , WLAN transceiver circuit  110  is active in RX or TX mode, whereas Bluetooth circuit  120  is inactive. The state of switch SW in transceiver circuit  110  may be used to determine whether transceiver circuit  110  is transmitting or receiving wireless LAN signals. State  216  corresponds to column  194  in the table of  FIG. 8 . During state  216 , switch SW 1  is on and switches SW 2  and SW 3  are off, so that signals may be conveyed between antenna  78  and transceiver circuit  120  with relatively low losses (e.g., about 1 dB). This is an improvement of about 2 dB relative to the loss exhibited when circuit  125  is in state  212  to support simultaneous operation of circuits  110  and  120 . 
     As indicated by line  204 , circuit  125  may be placed in state  214  by asserting signal TRANS 2 _ACTIVE and deasserting signal TRANS 1 _ACTIVE. Line  206  shows that circuit  125  can be returned to state  216  from state  214  by deasserting signal TRANS 2 _ACTIVE and asserting signal TRANS 1 _ACTIVE. 
     As described in connection with the embodiment of  FIG. 7 , circuit  125  may be controlled using two control signals (e.g., TRANS 1 _ACTIVE and TRANS 2 _ACTIVE). This is merely illustrative. Any suitable control arrangement may be used. For example, circuit  125  may be controlled using three control signals. 
     An embodiment of circuit  125  illustrating how three control signals may be used is shown in  FIG. 10 . In this embodiment, capacitor  218  (e.g., a 10 pF capacitor) serves to isolate switch SW 3  from the control signal TRANS 1 _ACTIVE, so that state of switch SW 3  is no longer controlled by signal TRANS 1 _ACTIVE. 
     Control signal TRANS 1 _ACTIVE may be taken high when transceiver  110  is active and may be taken low when transceiver  120  is active. Control signal TRANS 2 _ACTIVE may be taken high whenever it is desired to use transceiver  120  and may be taken low when transceiver  120  is not used. Control signal TRANS 1 AND 2 _ACTIVE may be taken high when it is desired to use both transceiver circuits  110  and  120  and may be taken low when both transceiver circuit  110  and transceiver circuit  120  are inactive. 
     When TRANS 1 AND 2 _ACTIVE is high on control terminal  224 , current flows through resistor  220  (e.g., a 2100 ohm resistor), diode  172 , and inductor  176  to ground  136 , forward biasing diode  172  and turning switch SW 3  on (i.e., placing switch SW 3  in its closed position). When TRANS 1 AND 2 _ACTIVE is low, control terminal  224  is low and no current flows through resistor  220 , diode  172 , and inductor  176  to ground  136 . In this situation, diode  172  is not forward biased and switch SW 3  is in its open (off) position. Capacitor  222  may form a low pass filter to help prevent radio-frequency signals from reaching node  224 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20070411
Publication Date: 20101019
Grant Date: 20101019
Priority Date: 20070411
Inventors: SANGUINETTI LOUIE J.
Assignee: APPLE INC
CPC Classifications: [{"code": "H04M2250/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M2250/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/406", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/006", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M2250/06", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/406", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/241", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/241", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M2250/02", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 39853631