Mobile wireless communications device having a single bluetooth / wireless local area network antenna and associated methods

A mobile wireless communications device includes a wireless local area network (WLAN) radio configured to generate a WLAN transmit signal, and a Bluetooth radio configured to generate a Bluetooth transmit signal. A circulator is coupled downstream of an antenna. A transmit path couples the WLAN radio and the Bluetooth radio to the circulator such that the WLAN radio and the Bluetooth radio are capable of transmitting simultaneously. In addition, a receive path also couples the WLAN radio and the Bluetooth radio to the circulator such that the WLAN radio and the Bluetooth radio are capable of receiving simultaneously.

TECHNICAL FIELD

The present disclosure relates to the field of communications, and, more particularly, to the field of mobile wireless communications devices.

BACKGROUND

Mobile wireless communications devices today are used for more than voice communications. Indeed, many mobile wireless communications devices today are capable of sending and receiving e-mail, browsing the Internet, executing a variety of applications, and playing media files. Indeed, given the ever increasing features present in mobile wireless communications devices, the delineation between them and traditional desktop computers is becoming less pronounced.

In fact, some mobile wireless communications devices today are capable of wireless communications that are not cellular in nature, such as wireless local area network (WLAN) communications and Bluetooth™ communications. While these additional capabilities are desired by users, they place additional requirements on the hardware of the mobile wireless communications devices. For example, to handle these additional wireless communications, mobile wireless communications devices typically have additional antennas and additional hardware. These additional antennas and hardware increase the size and weight of the device, as well as add cost the manufacture of the device. As such, new ways of adding non-cellular wireless communications functionality to mobile wireless communications devices are desirable.

DETAILED DESCRIPTION

Generally speaking, a mobile wireless communications device may include an antenna and a circulator coupled to the antenna. A wireless local area network (WLAN) radio may be configured to generate a WLAN transmit signal, and a Bluetooth radio may be configured to generate a Bluetooth transmit signal. In addition, the mobile wireless communications device may include a transmit path coupling the WLAN radio and the Bluetooth radio to the circulator such that the WLAN radio and the Bluetooth radio are capable of transmitting simultaneously. Similarly, the mobile wireless communications device may include a receive path also coupling the WLAN radio and the Bluetooth radio to the circulator such that the WLAN radio and the Bluetooth radio are capable of receiving simultaneously. The use of one antenna to transmit or receive both WLAN and Bluetooth at the same time, as opposed to prior art systems that use two separate antennae, advantageously saves space, weight, and cost.

In some applications, the transmit path may comprise a transmit power combiner configured to combine the WLAN transmit signal and the Bluetooth transmit signal into a combined transmit signal. In addition, the transmit path may further comprise a notch filter coupled downstream from the power transmit power combiner, and a power amplifier coupled downstream from the notch filter.

Further, the transmit path may comprise a bandpass filter coupled between the power amplifier and the circulator. Moreover, the transmit path may also include a bandpass filter coupled between the antenna and the circulator. A bandpass filter may be coupled to the circulator. An amplifier may be coupled between the Bluetooth radio and the bandpass filter.

The receive path may comprise a bandpass filter coupled downstream from the circulator, and a low noise amplifier downstream of the bandpass filter. The receive path may further comprise a receive power splitter downstream of the bandpass filter configured to separate the combined receive signal into a receive WLAN signal and a receive Bluetooth signal.

The circulator may be configured to couple the transmit path to the antenna and couple the receive path to the antenna while at least partially isolating the transmit path from the receive path.

A method aspect is directed to a method of making a mobile wireless communications device that may comprise coupling a circulator downstream of an antenna. The method may also include coupling a WLAN radio and a Bluetooth radio to the circulator via a transmit path such that the WLAN radio and the Bluetooth radio are capable of transmitting simultaneously. The method may further include coupling the WLAN radio and the Bluetooth radio to the circulator via a receive path such that the WLAN radio and the Bluetooth radio are capable of receiving simultaneously.

With reference toFIG. 1, a mobile wireless communications device10is now described. The mobile wireless communications device10has a dual band transceiver12that includes both a wireless local area network (WLAN radio14and a Bluetooth™ radio16. The dual band transceiver12may be an integrated circuit, for example, made by Broadcomm or Texas Instruments. Of course, it should be appreciated that other integrated circuits from other manufacturers may be used.

The mobile wireless communications device10includes a transmit path and a receive path. The transmit path includes both the WLAN radio14and the Bluetooth™ radio16. A transmit/receive switch28is coupled to the output of the Bluetooth™ radio16and receives a Bluetooth™ transmit signal therefrom. It should be appreciated that during Bluetooth™ transmission, the transmit/receive switch28is set to transmit, and during Bluetooth™ receipt, the transmit/receive switch28is set to receive.

The output of the transmit/receive switch28is in turn coupled to a power combiner30. The output of the WLAN radio14is also coupled to the power combiner, and sends a WLAN transmit signal thereto. The power combiner30combines the WLAN and Bluetooth™ transmit signals, advantageously allowing simultaneous transmission of both signals. The power combiner30is in turn coupled to a notch filter32, and sends the combined transmit signal (WLAN+Bluetooth™) thereto. The notch filter32reduces out of band white noise introduced to the combined transmit signal by either the WLAN radio14or the Bluetooth™ radio16. The notch filter32may filter out frequency components at 2.17 GHz, although it should be appreciated that other filters at other frequencies may also be used.

The output of the notch filter32is coupled to a power amplifier34, which amplifies the combined transmit signal. This advantageously allows the Bluetooth™ signal to be transmitted at a higher output level than it would be if there was a separate, dedicated power amplifier for the Bluetooth™ radio16. A switched power supply40is coupled to the power amplifier34, as is a line from the transceiver12carrying a bias voltage. The bias voltage and the supply voltage can be adjusted via the transceiver12and the switched power supply40, respectively, to thereby allow adjustment of the transmit power and linearity of the power amplifier34. The transmit power can be further adjusted by coupling the output of the power amplifier34to a power detector circuit in the transceiver12via a resistor36. The control over the transmit power and linearity provided by the above arrangement allows control of the power amplifier34without excessive DC power consumption.

The amplified combined transmit signal is output by the power amplifier34and fed to a bandpass filter38. The bandpass filter38helps to reduce out of band noise, reducing interference with other wireless signals. The insertion loss due to the bandpass filter38is relatively low since the bandpass filter mainly functions to reject out of band noise.

The output of the bandpass filter38is coupled to a circulator24, which passes the filtered, amplified, combined transmit signal to the antenna26, which wirelessly transmits that signal. As will be understood by those skilled in the art, the circulator24is a multi-port device which passes a signal received at a given port to the next port in rotation. Therefore, the circulator24passes the filtered, amplified, combined transmit signal to the antenna26from the bandpass filter38to the antenna26. Circulators24such as that employed in this disclosure provide excellent reverse isolation (as much as 15 dB in some applications), therefore mitigating load pulling effects on the power amplifier34due to an antenna mismatch.

The antenna26therefore simultaneously transmits both the WLAN signal and the Bluetooth™ signal. The use of one antenna to accomplish these transmissions, as opposed to prior art systems that use two separate antennae, saves space, weight, and cost. In addition, the mobile wireless communications device10has particularly good Bluetooth™ performance compared to conventional designs, as Bluetooth™ antennas in prior art devices are typically compromised in favor of a more effective WLAN antenna, by 2-3 dB in some situations.

Still referring toFIG. 1, the receive path is now described. The receive path includes the antenna26, which is in turn coupled to the circulator24, which is in turn coupled to a bandpass filter22. The circulator24passes a received combined signal from the antenna26to the bandpass filter22. It should be appreciated that the circulator24helps maintain good isolation between the transmit and receive paths, for example up to and even exceeding 10 dB in some applications.

The bandpass filter22, after filtering out of band noise, passes the received combined signal to a low noise amplifier20, which in turn passes an amplified received combined signal to a power splitter18. The power splitter splits the received WLAN signal from the received Bluetooth™ signal, sends the received WLAN signal to the WLAN radio14, and sends the received Bluetooth™ signal to the Bluetooth™ radio16. When the power splitter splits the signals18, it can split them at an equal ratio or an un-equal ratio, depending upon the application.

This mobile wireless communications device10saves antenna space by using one antenna26, as discussed above. It also has better receiver sensitivity for both the WLAN radio14and the Bluetooth™16radio due to the use of separate bandpass filters22,38for the receive path and the transmit path. The use of separate receive path and transmit path bandpass filters22,38allows the tuning of those filters to the paths, as opposed to a general purpose bandpass filter that would be used if the receive path and transmit path shared filters.

With reference toFIG. 2, a further embodiment of the mobile wireless communications device10′ is now described. In this embodiment, the transmit path lacks the transmit/receive switch. Rather, the power combiner30′ is directly coupled to the transceiver12′. In addition, the receive path lacks a power splitter, and the low noise amplifier20′ is directly coupled to the transceiver12′. The transceiver12′ includes first and second internal low noise amplifiers13′, for the received WLAN signal and the received Bluetooth™ signal, respectively. Elements not specifically described are similar to those in the mobile wireless communications device10ofFIG. 1described above and require no further discussion.

Yet another embodiment of a mobile wireless communications device10″ is now described with reference toFIG. 3. In this embodiment, the transmit path lacks the switched power supply, the notch filter, and the power combiner, while the transmit path is similar to the transmit path of the mobile wireless communications device10′ ofFIG. 2.

The transceiver12″ here includes first and second internal power amplifiers17″,19″ that amplify the transmit WLAN and Bluetooth™ signals, respectively. The first internal power amplifier17″ is directly coupled to the bandpass filter38″. The second internal power amplifier19″ is coupled to a first external power amplifier35″. This first external power amplifier35″ further amplifies the Bluetooth™ transmit signal such that it has a similar power level to the WLAN transmit signal.

The output of the first external power amplifier35″ is coupled to the output of the first internal power amplifier17″ and the input of the bandpass filter38″ via a coupling resistor36″. Elements not specifically described are similar to those in the mobile wireless communications device10ofFIG. 1described above and require no further discussion.

It should be appreciated that in some embodiments, the transmit and receive paths may share a single bandpass filter. As shown inFIG. 4, there may be a single bandpass filter39′″, and it may be positioned between the antenna26′″ and the circulator24′″. Elements not specifically described are similar to those in the mobile wireless communications device10ofFIG. 1described above and require no further discussion.

Example components of a mobile wireless communications device1000that may be used in accordance with the above-described embodiments are further described below with reference toFIG. 5. The mobile wireless communications device1000may function as either the electronic device described above, or the personal information token as described above. The device1000illustratively includes a housing1200, a keypad1400and an output device1600. The output device shown is a display1600, which may comprise a full graphic LCD. Other types of output devices may alternatively be utilized. A processing device1800is contained within the housing1200and is coupled between the keypad1400and the display1600. The processing device1800controls the operation of the display1600, as well as the overall operation of the mobile device1000, in response to actuation of keys on the keypad1400. Alternatively or additionally, the keypad1400may be a “soft” keypad implemented, for example, by providing images of keys on the display1600.

The housing1200may 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 device1800, other parts of the mobile device1000are shown schematically inFIG. 5. These include a communications subsystem1001; a short-range communications subsystem1020; the keypad1400and the display1600, along with other input/output devices1060,1080,1100and1120; as well as memory devices1160,1180and various other device subsystems1201. The mobile device1000may comprise a two-way RF communications device having data and, optionally, voice communications capabilities. In addition, the mobile device1000may have the capability to communicate with other computer systems via the Internet.

Operating system software executed by the processing device1800is stored in a persistent store, such as the flash memory1160, 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)1180. Communications signals received by the mobile device may also be stored in the RAM1180.

The processing device1800, in addition to its operating system functions, enables execution of software applications1300A-1300N on the device1000. A predetermined set of applications that control basic device operations, such as data and voice communications1300A and1300B, may be installed on the device1000during manufacture. In addition, a personal information manager (PIM) application may be installed during manufacture. The PIM may be capable of organizing and managing data items, such as e-mail, calendar events, voice mails, appointments, and task items. The PIM application may also be capable of sending and receiving data items via a wireless network1401. The PIM data items may be seamlessly integrated, synchronized and updated via the wireless network1401with corresponding data items stored or associated with a host computer system.

Communication functions, including data and voice communications, are performed through the communications subsystem1001, and possibly through the short-range communications subsystem. The communications subsystem1001includes a receiver1500, a transmitter1520, and one or more antennas1540and1560. In addition, the communications subsystem1001also includes a processing module, such as a digital signal processor (DSP)1580, and local oscillators (LOs)1601. The specific design and implementation of the communications subsystem1001is dependent upon the communications network in which the mobile device1000is intended to operate. For example, a mobile device1000may include a communications subsystem1001designed 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, WCDMA, PCS, GSM, EDGE, etc. Other types of data and voice networks, both separate and integrated, may also be utilized with the mobile device1000. The mobile device1000may also be compliant with other communications standards such as 3GSM, 3GPP, UMTS, 4G, etc.

When required network registration or activation procedures have been completed, the mobile device1000may send and receive communications signals over the communication network1401. Signals received from the communications network1401by the antenna1540are routed to the receiver1500, 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 DSP1580to perform more complex communications functions, such as demodulation and decoding. In a similar manner, signals to be transmitted to the network1401are processed (e.g. modulated and encoded) by the DSP1580and are then provided to the transmitter1520for digital to analog conversion, frequency up conversion, filtering, amplification and transmission to the communication network1401(or networks) via the antenna1560.

In addition to processing communications signals, the DSP1580provides for control of the receiver1500and the transmitter1520. For example, gains applied to communications signals in the receiver1500and transmitter1520may be adaptively controlled through automatic gain control algorithms implemented in the DSP1580.

In a data communications mode, a received signal, such as a text message or web page download, is processed by the communications subsystem1001and is input to the processing device1800. The received signal is then further processed by the processing device1800for an output to, the display1600, or alternatively to some other auxiliary input/output (I/O) device1060. A device may also be used to compose data items, such as e-mail messages, using the keypad1400and/or some other auxiliary I/O device1060, such as a trackball, a touchpad, a rocker switch, a thumb-wheel, touch sensitive display or some other type of input device. The composed data items may then be transmitted over the communications network1401via the communications subsystem1001.

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 speaker1100, and signals for transmission are generated by a microphone1120. Alternative voice or audio I/O subsystems, such as a voice message recording subsystem, may also be implemented on the device1000. In addition, the display1600may 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.

The short-range communications subsystem enables communication between the mobile device1000and 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.