PATENT DOCUMENT

Publication Number: US-9391570-B2
Application Number: US-201414333912-A
Country: US
Kind Code: B2

Title: Electronic device with low noise amplifier module

Abstract:
An electronic device may include an antenna, a transceiver, and a low noise amplifier module that amplifies receive signals from the antenna to the transceiver circuitry in a first configuration and passes transmit signals from the transceiver to the antenna in a second configuration. The low noise amplifier module may include a first switching circuit coupled to the antenna, a second switching circuit coupled to the transceiver, at least one low noise amplifier coupled between the first and second switching circuits, and a transmit bypass path coupled between the first and second switching circuits. The transceiver may be located in a first electronic device region, whereas the low noise amplifier module and the antenna may be located in a second region. The low noise amplifier module may help compensate for signal loss between the first and second regions and allow for transmit signals to pass to the antenna.

Claims:
What is claimed is: 
     
       1. An electronic device having first and second regions located at opposing ends of the electronic device, comprising:
 an antenna in the second region of the electronic device; 
 transceiver circuitry in the first region of the electronic device; 
 a low noise amplifier module in the second region of the electronic device and coupled between the transceiver circuitry and the antenna, wherein the low noise amplifier module amplifies receive signals from the antenna to the transceiver circuitry in a first configuration and passes transmit signals from the transceiver circuitry to the antenna in a second configuration, the antenna comprising a first antenna; and 
 a second antenna in the first region of the electronic device, wherein the first antenna is located at a first distance from the transceiver circuitry, the second antenna is located at a second distance from the transceiver circuitry, the first distance is greater than the second distance, and the low noise amplifier module compensates for increased signal loss associated with the first distance. 
 
     
     
       2. The electronic device defined in  claim 1 , and wherein the electronic device further comprises:
 a transmission line that connects the first and second regions of the electronic device, wherein the transmission line conveys the transmit signals from the transceiver circuitry to the low noise amplifier module and conveys the amplified receive signals from the low noise amplifier module to the transceiver circuitry. 
 
     
     
       3. The electronic device defined in  claim 1  further comprising:
 switching circuitry located in the first region of the electronic device, wherein the switching circuitry selectively couples transmitter circuitry in the transceiver circuitry to the first and second antennas to provide antenna transmit diversity. 
 
     
     
       4. The electronic device defined in  claim 1  wherein the low noise amplifier module comprises:
 a first switching circuit coupled to the antenna; 
 a second switching circuit coupled to the transceiver circuitry; 
 at least one low noise amplifier coupled between the first and second switching circuits; and 
 a transmit bypass path coupled between the first and second switching circuits. 
 
     
     
       5. The electronic device defined in  claim 4  wherein the at least one low noise amplifier comprises a plurality of low noise amplifiers for different frequency bands. 
     
     
       6. The electronic device defined in  claim 5  wherein the plurality of low noise amplifiers comprises first and second low noise amplifiers and wherein the low noise amplifier module further comprises:
 a filtering circuit coupled between the first low noise amplifier and the first switching circuit; and 
 a third switching circuit coupled between the first low noise amplifier and the filtering circuit. 
 
     
     
       7. The electronic device defined in  claim 6  wherein the filtering circuit comprises a first filter for a first frequency band and a second filter for a second frequency band and wherein the third switching circuit electrically couples a selected one of the first and second filters to the first low noise amplifier. 
     
     
       8. The electronic device defined in  claim 6  wherein the low noise amplifier module further comprises:
 a duplexer having a first filter that is coupled between the second switching circuit and the first low noise amplifier and a second filter that is coupled between the second switching circuit and the second low noise amplifier. 
 
     
     
       9. An electronic device, comprising:
 an antenna; 
 transceiver circuitry; 
 a low noise amplifier module coupled between the transceiver circuitry and the antenna, wherein the low noise amplifier module amplifies receive signals from the antenna to the transceiver circuitry in a first configuration and passes transmit signals from the transceiver circuitry to the antenna in a second configuration, the low noise amplifier module comprising:
 a first switching circuit coupled to the antenna; 
 a second switching circuit coupled to the transceiver circuitry; 
 at least one low noise amplifier coupled between the first and second switching circuits; 
 a transmit bypass path coupled between the first and second switching circuits; 
 a first tunable filter coupled between the low noise amplifier and the first switching circuit; and 
 a second tunable filter coupled between the second switching circuit and the low noise amplifier. 
 
 
     
     
       10. A low noise amplifier module, comprising:
 first and second ports; 
 a low noise amplifier coupled between the first and second ports, wherein the low noise amplifier is configured to amplify receive signals at the second port; 
 a transmit bypass path for passing transmit signals from the first port to the second port; 
 a first switching circuit that selectively couples the first port to the low noise amplifier and the transmit bypass path; 
 a second switching circuit that selectively couples the low noise amplifier and the transmit bypass path to the second port; and 
 a third switching circuit interposed between the low noise amplifier and the second switching circuit. 
 
     
     
       11. The low noise amplifier module defined in  claim 10  wherein the low noise amplifier comprises one of a plurality of low noise amplifiers that are coupled between the first and second ports and wherein each of the plurality of low noise amplifiers handles a respective frequency band, the low noise amplifier further comprising:
 filtering circuitry, wherein the third switching circuit is interposed between the plurality of low noise amplifiers and the filtering circuitry, and the third switching circuit and the filtering circuitry is configured to filter the receive signals into the frequency bands for amplification by the plurality of low noise amplifiers. 
 
     
     
       12. The electronic device defined in  claim 9 , further comprising:
 control circuitry; and 
 control paths, wherein the control circuitry is configured to tune the first and second tunable filters by providing control signals to the first and second tunable filters over the control paths. 
 
     
     
       13. The electronic device defined in  claim 9 , wherein the low noise amplifier further comprises:
 an additional filter coupled between the first tunable filter and the first switching circuit. 
 
     
     
       14. The electronic device defined in  claim 9 , wherein the low noise amplifier further comprises:
 a first filter coupled between the second tunable filter and the second switching circuit. 
 
     
     
       15. The electronic device defined in  claim 14 , wherein the low noise amplifier further comprises:
 a second filter coupled between the first tunable filter and the first switching circuit. 
 
     
     
       16. The electronic device defined in  claim 15 , wherein the low noise amplifier further comprises:
 an additional low noise amplifier coupled between the first and second filters; 
 a third tunable filter coupled between the additional low noise amplifier and the first filter; and 
 a fourth tunable filter coupled between the additional low noise amplifier and the second filter.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with antennas. 
     Electronic devices often include antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. 
     Electronic devices often are required to support wireless communications in multiple frequency bands. With compact electronic devices such as mobile electronic devices, it can be challenging for antenna structures to support the various frequency bands while being limited by device area or volume constraints. One antenna is often required to handle communications in multiple frequency bands. 
     Front-end circuitry such as filters and switches are used to separate radio-frequency signals of different frequency bands that are received at a particular antenna. The front-end circuitry conveys receive and transmit signals between radio-frequency transceiver circuitry and one or more antennas. However, it can be challenging to ensure adequate wireless performance. For example, antennas may be located at different distances from the transceiver circuitry. An antenna located at a distance away from transceiver circuitry may require connection via a radio-frequency transmission line such as a coaxial cable. Antennas located at different distances may be subject to different amounts of signal loss, which adversely impacts wireless performance. Filters and switches may also impart different amounts of loss when conveying radio-frequency signals of different frequency bands. In addition, signals of different frequency bands can potentially cause interference due to nonlinear circuit operation. 
     It would therefore be desirable to be able to provide improved radio-frequency front end circuitry for wireless electronic devices. 
     SUMMARY 
     An electronic device may include an antenna, transceiver circuitry, and a low noise amplifier module that amplifies receive signals from the antenna to the transceiver circuitry in a first configuration and passes transmit signals from the transceiver circuitry to the antenna in a second configuration. The low noise amplifier module may include a first switching circuit coupled to the antenna, a second switching circuit coupled to the transceiver circuitry, at least one low noise amplifier coupled between the first and second switching circuits, and a transmit bypass path coupled between the first and second switching circuits. Filtering circuitry may be interposed between the first switching circuit and the low noise amplifier to help block transmit signal leakage from reaching the low noise amplifier. 
     The transceiver circuitry may be located in a first region of the electronic device, whereas the low noise amplifier module and the antenna may be located in a second region of the electronic device. The first and second regions may be located at opposing ends of the electronic device. A transmission line may connect the first and second regions of the electronic device. The transmission line may convey transmit signals from the transceiver circuitry to the low noise amplifier module and may convey the amplified receive signals from the low noise amplifier module to the transceiver circuitry. 
     The electronic device may include a second antenna in the first region of the electronic device in addition to the first antenna located in the second region of the electronic device. Switching circuitry located in the first region of the electronic device may selectively couple transmitter circuitry in the transceiver circuitry to the first and second antennas to provide antenna transmit diversity. The low noise amplifier module may help compensate for signal loss over the transmission line while accommodating antenna transmit diversity operations by passing transmit signals to the first antenna. 
     The low noise amplifier module may include multiple low noise amplifiers each handling amplification of receive signals in different frequency bands. Filtering circuitry may be provided to filter the receive signals into the frequency bands for amplification by the low noise amplifiers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an illustrative electronic device with wireless circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic view of an illustrative electronic device with low noise amplifier circuitry that passes transmit signals in accordance with an embodiment. 
         FIG. 3  is a diagram of an illustrative electronic device including low noise amplifier circuitry that may compensate for signal loss in a transmission line that connects first and second regions of the electronic device in accordance with an embodiment. 
         FIG. 4  is a diagram of illustrative low noise amplifier circuitry that passes transmit signals via a transmit bypass path in accordance with an embodiment. 
         FIG. 5  is a diagram of illustrative low noise amplifier circuitry that passes transmit signals via a transmit bypass path and includes filtering and switching circuitry that separates radio-frequency bands for low noise amplifiers in accordance with an embodiment. 
         FIG. 6  is a diagram of illustrative low noise amplifier circuitry that passes transmit signals via a transmit bypass path and includes tunable filters for handling multiple frequency bands in accordance with an embodiment. 
         FIG. 7  is a diagram of illustrative low noise amplifier circuitry that passes transmit signals via a transmit bypass path and includes carrier aggregation bypassing switches in accordance with an embodiment. 
         FIG. 8  is a flow chart of illustrative steps that may be performed in configuring and using a low noise amplifier module having transmit bypass capabilities in accordance with an embodiment. 
         FIG. 9  is an illustrative diagram showing how frequency multiplexing circuitry may be implemented as a triplexer. 
         FIG. 10  is an illustrative diagram showing how frequency multiplexing circuitry may be implemented as a quadplexer. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as device  10  of  FIG. 1  may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support long-range wireless communications such as communications in cellular telephone bands. Examples of long-range (cellular telephone) bands that may be handled by device  10  include the 800 MHz band, the 850 MHz band, the 900 MHz band, the 1800 MHz band, the 1900 MHz band, the 2100 MHz band, the 700 MHz band, and other bands. The long-range bands used by device  10  may include the so-called LTE (Long Term Evolution) bands. The LTE bands are numbered (e.g.,  1 ,  2 ,  3 , etc.) and are sometimes referred to as E-UTRA operating bands. Long-range signals such as signals associated with satellite navigation bands may be received by the wireless communications circuitry of device  10 . For example, device  10  may use wireless circuitry to receive signals in the 1575 MHz band associated with Global Positioning System (GPS) communications. Short-range wireless communications may also be supported by the wireless circuitry of device  10 . For example, device  10  may include wireless circuitry for handling local area network links such as WiFi® links at 2.4 GHz and 5 GHz, Bluetooth® links at 2.4 GHz, etc. 
     As shown in  FIG. 1 , device  10  may include storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be 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, functions related to communications band selection during radio-frequency transmission and reception operations, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  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, cellular telephone protocols, MIMO (multiple input multiple output) protocols, antenna diversity protocols, etc. Wireless communications operations such as communications band selection operations may be controlled using software stored and running on device  10  (i.e., stored and running on storage and processing circuitry  28  and/or input-output circuitry  30 ). 
     Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  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. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . Transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in cellular telephone bands such as at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz and/or the LTE bands and other bands (as examples). Circuitry  38  may handle voice data and non-voice data. Wireless communications circuitry  34  may include baseband circuitry that handles baseband signals that are up-converted to radio-frequency (e.g., during signal transmission) or down-converted (e.g., during signal reception). 
     Wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment such as GPS receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include one or more antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structure, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. 
     Antenna diversity schemes may be implemented in which multiple redundant antennas are used in handling communications for a particular band or bands. In an antenna diversity scheme, storage and processing circuitry  28  may select which antenna to use in real time based on signal strength measurements or other data. In multiple-input-multiple-output (MIMO) schemes, multiple antennas may be used to transmit and receive multiple data streams, thereby enhancing data throughput. 
     Illustrative locations in which antennas  40  may be formed in device  10  are shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may have a housing such as housing  12 . Housing  12  may include plastic walls, metal housing structures, structures formed from carbon-fiber materials or other composites, glass, ceramics, or other suitable materials. Housing  12  may be formed using a single piece of material (e.g., using a unibody configuration) or may be formed from a frame, housing walls, and other individual parts that are assembled to form a completed housing structure. The components of device  10  that are shown in  FIG. 1  may be mounted within housing  12 . Antenna structures  40  may be mounted within housing  12  and may, if desired, be formed using parts of housing  12 . For example, housing  12  may include metal housing sidewalls, peripheral conductive members such as band-shaped members (with or without dielectric gaps), conductive bezels, and other conductive structures that may be used in forming antenna structures  40 . 
     As shown in  FIG. 2 , antenna structures  40  may be coupled to transceiver circuitry  90  by paths such as paths  45 . Paths  45  may include transmission line structures such as coaxial cables, microstrip transmission lines, stripline transmission lines, etc. Paths  45  may also include impedance matching circuitry, filter circuitry, and switching circuitry. Impedance matching circuitry may be used to ensure that antennas  40  are efficiently coupled to transceiver circuitry  90  in communications bands of interest. Filter circuitry may be used to implement frequency-based multiplexing circuits such as diplexers, duplexers, or other multiplexing circuits. Switching circuitry may be used to selectively couple antennas  40  to desired ports of transceiver circuitry  90 . For example, in one operating mode a switch may be configured to route one of paths  45  to a given antenna and in another operating mode the switch may be configured to route a different one of paths  45  to the given antenna. The use of switching and filtering circuitry between transceiver circuitry  90  and antennas  40  allows device  10  to support multiple communications bands of interest with a limited number of antennas. 
     In a device such as a cellular telephone that has an elongated rectangular outline, it may be desirable to place antennas  40  at one or both ends of the device. As shown in  FIG. 2 , for example, some of antennas  40  may be placed in upper end region  43  of housing  12  and some of antennas  40  may be placed in lower end region  44  of housing  12 . The antenna structures in device  10  may include a single antenna in region  43 , a single antenna in region  44 , multiple antennas in region  43 , multiple antennas in region  44 , or may include one or more antennas located elsewhere in housing  12 . 
     Antenna structures  40  may be formed within some or all of regions such as regions  43  and  44 . For example, an antenna such as antenna  40 T- 1  may be located within region  43 - 1  or an antenna such as antenna  40 T- 2  may be formed that fills some or all of region  43 - 1 . An antenna such as antenna  40 B- 1  may fill some or all of region  44 - 2  or an antenna such as antenna  40 B- 2  may be formed in region  44 - 1 . These types of arrangements need not be mutually exclusive. For example, region  44  may contain a first antenna such as antenna  40 B- 1  and a second antenna such as antenna  40 B- 2 . 
     Transceiver circuitry  90  may contain transmitters such as transmitters  48  and receivers such as receivers  50 . Transmitters  48  and receivers  50  may be implemented using one or more integrated circuits (e.g., cellular telephone communications circuits, wireless local area network communications circuits, circuits for Bluetooth® communications, circuits for receiving satellite navigation system signals, power amplifier circuits for increasing transmitted signal power, low noise amplifier circuits for increasing signal power in received signals, other suitable wireless communications circuits, and combinations of these circuits). 
     Device  10  may be a relatively large device (e.g. the lateral dimensions of housing  12  may be tens of centimeters or larger) or may be a relatively compact device such as a handheld device that has a longitudinal dimension along the main axis of housing  12  that is 15 cm or less, 10 cm or less, or 5 cm or less, and that has smaller transverse dimensions. 
     In some scenarios, antennas  40  may be located at different distances from transceiver circuitry  90 . In the example of  FIG. 2 , upper device region  43  may be separated from transmitters  48  and receivers  50  of transceiver  90  by distance D 1 , whereas lower device region  44  may be separated from transceiver  90  by distance D 2 . Distance D 1  may be greater than distance D 2 . For example, transceiver circuitry  90  may be mounted on a printed circuit board nearby or adjacent to lower region  44 . Transmit and receive signals passed between transceiver circuitry  90  and upper region  43  may therefore traverse longer paths  45  than signals between transceiver circuitry  90  and lower region  44 . 
     Paths  45  may cause loss in signals that are conveyed across the paths. The amount of loss is dependent on the length of the paths such that longer paths exhibit greater amounts of signal loss, whereas shorter paths have less signal loss. Paths  45  between upper device region  43  and transceiver circuitry  90  are longer than paths  45  between lower device region  44  and transceiver circuitry  90 , and therefore signals for antennas in upper device region  43  may experience a greater amount of signal loss. 
     Low noise amplifier module  52  may be interposed in path  45  between an antenna of region  43  (e.g., antenna  40 T- 1 ) and transmitters and receivers of transceiver circuitry  90 . Low noise amplifier module  52  may help to compensate for signal loss between antenna  40 T- 1  and receivers  50  (e.g., signal loss due to the increased length of transmission path  45 ) by amplifying received antenna signals. For example, low noise amplifier module  52  may provide about 3 dB of amplification for signals received by antenna  40 T- 1 . 
     Low noise amplifier module  52  may be connected to one or more antennas  40  in upper region  43 . In some scenarios, amplification may be omitted. For example, paths  45  may provide sufficient wireless performance for the wireless communications at antenna  40 T- 2  without amplification by low noise amplifier module  52 . 
     During normal operation, one or more antennas  40  may experience degraded performance. For example, a user may inadvertently block antennas in lower region  44  or antennas in upper region  43 . To help ensure adequate wireless performance, antennas  40  of device  10  may be configured to implement antenna transmit diversity. In particular, switching circuitry in paths  45  may be configured to swap which antennas are used for transmitting radio-frequency signals. In response to detecting reduced performance at a first antenna in a first region of device  10  (e.g., lower region  44 ), device  10  may configure the switching circuitry to route transmit signals to a second, opposing antenna in a second region of device  10  (e.g., upper region  44  that is located at an opposite end of device  10 ). 
     Low noise amplifier module  52  may be provided with the capability of passing transmit signals from transmitters  48  to antennas in addition to amplifying receive signals from the antennas. Module  52  may therefore be sometimes referred to herein as a bi-directional module, because module  52  passes signals in both directions between antennas and transceiver circuitry. The bi-directional capabilities of module  52  may help to accommodate transmit diversity (e.g., when transmit signals are routed to antenna  40 T- 1 ) in addition to compensating for receive signal loss due to longer signal path lengths. 
     Each antenna may be configured to handle wireless communications in multiple radio-frequency bands.  FIG. 3  is a diagram of an illustrative electronic device  10  in which antennas handle multiple radio-frequency bands. 
     As shown in  FIG. 3 , device  10  may include wireless circuitry in regions  102  and  104  of the electronic device. For example, region  102  may include upper device region  43  of  FIG. 2 , whereas region  104  may include lower device region  44 . 
     Region  102  of device  10  may include antennas  40 T- 1  and  40 T- 2 . Antennas  40 T- 1  and  40 T- 2  may handle wireless communications in different communications bands. In the example of  FIG. 3 , antenna  40 T- 1  may handle cellular, GPS, and WiFi signals in frequency bands within the 699-2690 MHz frequency range, whereas antenna  40 T- 2  may handle WiFi signals in the 5 GHz WiFi frequency band. 
     WiFi transmit and receive signals associated with antennas  40 T- 1  and  40 T- 2  may be handled by WiFi communications circuitry  106 . WiFi communications circuitry  106  may include transceiver circuitry such as WiFi transceiver circuitry  36  of  FIG. 1 . In the example of  FIG. 3 , WiFi communications circuitry is located in region  102 . If desired, WiFi communications circuitry (e.g., including transceiver and/or baseband circuitry) may be located at any desired location within device  10 . 
     Region  102  may include frequency-based multiplexing circuitry  108  that helps to separate wireless signals in different frequency bands. Multiplexing circuitry  108  may include filters that isolate wireless signals in different ranges of frequencies. In the example of  FIG. 3 , multiplexing circuitry  108  may isolate low band (LB) signals, combined mid-band (MB) and high-band (HB) signals, GPS signals, and WiFi signals (e.g., for 2.4 GHz WiFi). For example, multiplexing circuitry  108  may include a filter that covers multiple low bands such as cellular LTE bands  12 ,  13 ,  17 ,  28 ,  29 ,  20 ,  27 ,  26 ,  8  etc. As another example, multiplexing circuitry  108  may include a filter that covers multiple mid-bands and high-bands such as cellular LTE bands  25 ,  1 ,  3 ,  4 ,  7 ,  30 , etc. 
     Region  102  may be relatively remote to region  104  that includes transceiver circuitry  90 . For example, region  102  may be an upper device region located at first end of device  10 , whereas region  104  may be a lower device region located at a second, opposing end of device  10 . Region  102  may be connected to region  104  via transmission lines  110  such as coaxial transmission lines (e.g.,  110 - 1 ,  110 - 2 , and  110 - 3 ). Due to the length of transmission lines  110 , signals for antenna  40 T- 1  in region  102  may experience greater signal loss than signals for antenna  40 B- 1  in region  104  (e.g., because antenna  40 T- 1  is located farther from transceiver  90  than antenna  40 B- 1 ). 
     Amplifier circuitry may be provided in region  102  to help compensate for increased signal loss associated with antenna  40 T- 1 . Wireless communications such as GPS that are receive-only may be provided with a low noise amplifier (LNA) such as LNA  112 . Wireless communications such as cellular communications that potentially require bi-directional communications may be provided with a bi-directional amplifier module  52  that provides low noise amplification for receive signals in addition to passing transmit signals. As shown in  FIG. 3 , amplifier module  52  may be connected to and handle radio-frequency signals in mid-band and high-band frequencies. If desired, amplifier module  52  may be connected to the low band filter via optional path  118  and handle radio-frequency signals in the low frequency band. 
     Low noise amplifier module  52  may receive a bias voltage VBIAS from power supply circuitry  114 . Bias voltage VBIAS may bias transistors in module  52  to provide a desired amount of linearity while conserving power. For example, bias voltage VBIAS may be a bias voltage provided to the gates of transistors or may be a power supply voltage (e.g., VDD) that supplies power to the transistors. If desired, power supply circuitry  114  may adjustable and provide an adjustable bias voltage that is adjusted in real time based on desired amplifier performance. 
     Region  104  of device  10  may include transceiver circuitry  90 , baseband circuitry  116 , and front-end circuitry such as switches and filters. Transceiver circuitry  90  handles transmitting and receiving radio-frequency signals. Transceiver circuitry  90  may receive baseband transmit signals from baseband circuitry  10  and up-convert the baseband transmit signals into radio-frequency signals in appropriate frequency bands. Transceiver circuitry  90  may receive radio-frequency signals from antennas  40  and down-convert the radio-frequency receive signals to baseband receive signals for processing by baseband circuitry  116 . 
     Front-end circuitry in region  104  of device  10  may include switching circuitry  122  and  124  and diplexer  120 . Diplexer  120  may serve to isolate and separate signals of different frequency ranges for antenna  40 B- 1 . Low band signals may be isolated from mid-band and high-band signals. Low band signals associated with antennas  40 B- 1  and  40 T- 1  may be routed to respective ports of low band switching circuitry  124 . Low band switching circuitry may be coupled to transceiver circuitry  90  via multiple paths that each handles wireless communications in a respective portion of the low band. For example, the low band may include multiple cellular bands each associated with a respective path between transceiver circuitry  90  and low band switching circuitry  124 . Low band switching circuitry  124  may be configured to select which antenna is used for transmitting and/or receiving signals. For example, low band switching circuitry  124  may be configured for antenna transmit diversity by selecting which antenna is connected to transceiver circuitry  90  during transmit operations in the low band frequency range. 
     Mid-band and high-band (MB/HB) switching circuitry  122  may be similarly connected to antennas  40 B- 1  and  40 T- 1  to provide transmit diversity capabilities. Duplexers such as duplexer  126  may be used to provide carrier aggregation capabilities. Duplexer  126  includes two filters that isolate radio-frequency signals in different frequency bands. Duplexer  126  includes a first port that is coupled to MB/HB switching circuitry  122  via path  130 . Duplexer  126  includes second and third ports that are coupled via switches  134  to paths  128  and  130 , respectively. Duplexer  126  allows for combining transmit signals in different frequency bands and separating receive signals for processing. 
     As an example, path  128  may convey LTE band  1  to and from transceiver circuitry  90 , whereas path  132  handles LTE band  7  signals. During carrier aggregation operations, switches  134  may be closed (enabled) to pass the LTE band  1  and band  7  signals to duplexer  126 . Duplexer  126  provides combined LTE band  1  and band  7  signals to switching circuitry  122  via path  130 . Similarly, receive signals from the antennas may be separated in frequency bands by duplexer  126  and conveyed to transceiver circuitry  90  over appropriate paths  128  and  132 . 
     Switches  134  and paths  128  and  132  may provide improved performance in scenarios such as when device  10  can operate in carrier aggregation and non-carrier aggregation modes. Consider the scenario in which LTE communications sometimes requires carrier aggregation between first and second LTE frequency bands and requires independent communications in the first and second LTE bands at other times. In this scenario, switches  134  may be closed to enable carrier aggregation and opened to disable carrier aggregation between the frequency bands of paths  128  and  132 . When switches  134  are opened, communications on paths  128  and  132  may be performed independently without any losses from duplexer  126  (e.g., because duplexer  126  is disconnected from paths  128  and  132 ). 
     Front-end circuitry such as switching circuitry  122 ,  124 , and  134  may be controlled by baseband circuitry  116  via respective control signal paths (not shown) that couple baseband circuitry  116  to each circuit. Similarly, baseband circuitry  116  may provide control signals that control power supply circuitry  114  to provide a desired VBIAS to amplifier module  52 . 
       FIG. 4  is an illustrative diagram of a low noise amplifier module  52  that passes transmit signals in addition to providing low noise amplification of receive signals. As shown in  FIG. 4 , amplifier module  52  may include low noise amplifiers  152  and transmit (TX) bypass path  160  coupled in parallel between switching circuitry  156  and  158 . Each low noise amplifier  152  may amplify signals in a respective set of one or more frequency bands (e.g., LTE frequency bands). Switching circuitry  156  and  158  may be configured (e.g., by baseband circuitry) to selectively couple one of the low noise amplifiers  152  (e.g., in a first switch configuration) or transmit bypass path  160  (e.g., in a second switch configuration) to the antenna via port  162 . Similarly, switching circuitry  156  and  158  may be configured to selectively couple one of the low noise amplifiers  152  or transmit bypass path  160  to transceiver circuitry via port  164 . If desired, switching circuitry  156  and  158  may be configured to simultaneously connect transmit bypass path  160  and a low noise amplifier  152  between ports  162  and  164 . 
     Switching and/or filter circuitry  154  may be used to separate and isolate signals for low noise amplifiers  152  (e.g., signals in different LTE frequency bands for each respective low noise amplifier). 
     Transmit bypass path  160  provides amplifier module  52  with the capability of passing transmit signals from port  164  to port  162  in addition to low noise amplification capabilities provided by low noise amplifiers  152 . Switching circuitry  156  and  158  may electrically disconnect LNA amplifiers  152  during an antenna diversity mode in which transmit bypass path  160  is electrically connected between ports  164  and  162 . If desired, switching circuitry  156  and  158  may toggle between connecting LNA amplifiers  152  and TX bypass path (e.g., in a time sharing arrangement), may simultaneously connect transmit bypass path  160  and a low noise amplifier  152 . 
     Switching and filter circuitry  154  may include any desired combination of switching and filtering circuitry for separating and isolating signals for amplification by low noise amplifiers  152 .  FIG. 5  is a diagram of amplifier module  52  with illustrative switching and filter circuitry  154 . As shown in  FIG. 5 , circuitry  154  may include switching circuitry  162 ,  164 , and  166  and filtering circuitry such as duplexers  168 ,  172 , and  174 , and triplexer  170 . Duplexers  168 ,  172 , and  174 , and triplexer  170  separate signals in different frequency bands (e.g., LTE bands) while helping to reduce the number of required switch ports on switching circuitry  156  (e.g., by combining signals of multiple frequency bands). 
     Switches  162 ,  164 , and  166  may select between paths associated with different frequency bands and also help to ensure isolation between the frequency bands. As shown in  FIG. 5 , each switch of circuitry  154  may have any desired number of switch ports (e.g., two, three, four, or more) that are selectively coupled to a low noise amplifier  152  for amplification. 
     If desired, multiple LNA paths (i.e., paths between switches  156  and  158  that include LNAs  152 ) may be combined when coupling to switch  158  by filters such as duplexer  176 . Duplexer  176  may help to ensure that signals associated with LNA paths  178  and  180  are isolated. In other words, duplexer  176  may help to prevent interference between paths  178  and  180 . 
     In some scenarios, communications at two different frequencies can cause interference at a third frequency. Consider the scenario in which path  180  handles LTE band  7  receive signals between 2620 to 2690 MHz, whereas transceiver circuitry simultaneously transmits radio-frequency signals in LTE band  7  from antenna  40 B- 1  of  FIG. 3  and handles WiFi communications with antenna  40 T- 1 . WiFi signals at 2.4 GHz may leak to the inputs of LNA amplifiers  152  (e.g., due to imperfect filtering at multiplexing circuitry  108  of  FIG. 3 ), whereas the LTE band  7  transmit signals may leak to the outputs of LNA amplifiers  152  (e.g., due to imperfect isolation at MB/HB switching circuitry  122 . In this scenario, intermodulation at the output of LNAs  152  (sometimes referred to as reverse intermodulation) may produce third order nonlinearities at frequencies within the LTE band  7  receive range (i.e., 2620 to 2690). Duplexer  176  may help to prevent such reverse modulation scenarios, because duplexer  176  helps prevent mixing of the WiFi and LTE band  7  transmit signals at the output of LNA amplifiers  152  on paths  178  and  180 . If desired, the linearity of amplifiers  152  on paths  178  and  180  may be adjusted in response to scenarios in which reverse intermodulation may occur (e.g., when antenna  40 T- 1  is handling 2.4 GHz WiFi and LTE band  7  receive and antenna  40 B- 1  is handling LTE band  7  transmit). The linearity of amplifiers  152  may be adjusted by baseband circuitry via control signals that direct adjustable power supply circuitry to adjust the bias voltages provided to the amplifiers. 
     The example of  FIG. 5  in which switching and filter circuitry  154  is used to partition communications in frequency for LNA paths is merely illustrative. If desired, switching circuitry in some or all of the LNA paths may be omitted such that each LNA  152  handles radio-frequency signals in only one communications frequency band. For example, switching circuitry  162  may be omitted and a low noise amplifier  152  may be connected to each filter of duplexer  168  (i.e., the ratio of low noise amplifiers to receive bands may be  1 : 1 ). Omission of switching circuitry may help to improve performance, whereas use of switching circuitry may help to minimize the number of low noise amplifiers and therefore potentially reduce cost. 
     The example of  FIG. 5  in which multiple frequency filters for low noise amplifiers  152  are used is merely illustrative. As shown in  FIG. 6 , tunable filter circuitry may be used in separately amplifying receive signals. Tunable filters  182  may be adjusted independently or in groups by control signals provided by baseband circuitry over control paths. For example, tunable filters  182  may be adjusted to pass only radio-frequency signals within a desired frequency band while rejecting signals outside of the desired frequency band. If desired, duplexers  184  and  185  may be coupled to LNAs  152  to provide carrier aggregation. Duplexer  184  may separate receive signals for separate amplification by LNAs  152 , whereas duplexer  185  may combine the amplified signals for conveying to transceiver circuitry. 
     Switches  186  and  188  may be configured to selectively connect TX and RX paths between transceiver circuitry and antennas, which provides amplifier module  52  with the capability of low noise amplification via amplifiers  152  in addition to passing transmit signals via bypass path  160 . 
     In the example of  FIG. 6 , amplifier module  52  may include ports  194  and  196  that handle low band signals (e.g., port  194  may be connected to a port of multiplexing circuitry  108  for low band signals via path  118  of  FIG. 3 ). Amplifier module  52  may include low noise amplifier circuitry with a low band transmit bypass path  160  similarly to MB/HB amplifier circuitry connected between ports  162  and  164 . The low band circuitry may include only one LNA path (LNA  152  and tunable filters  182 ) as shown in  FIG. 6  or may include additional LNA paths and, if desired, may include filters such as duplexer  185  for carrier aggregation of LTE bands within the low band frequency range. 
     As shown in  FIG. 7 , additional switching circuits may be added to module  52  of  FIG. 6  to provide dedicated paths when carrier aggregation is disabled or otherwise used. Additional switches  202  may be interposed between LNAs  152  and duplexer  184 . Switches  202  may be configured to switch between a first configuration in which carrier aggregation is performed using duplexer  184  and a second configuration in which switches  202  connect LNAs  152  to paths  204  and  206  (e.g., bypassing duplexer  184 , which prevents signal loss associated with duplexer  184 ). In the second configuration, paths  204  and  206  may independently handle radio-frequency signals on different frequency bands. 
       FIG. 8  is a flow chart  210  of illustrative steps that may be used in configuring a low noise amplifier module having transmit bypass and using the low noise amplifier module to amplify receive signals while accommodating transmit diversity. The operations of flow chart  210  may, for example, be performed by generating and providing control signals using baseband circuitry or other control circuitry in an electronic device. The electronic device may implement antenna transmit diversity using a primary antenna that is normally used for signal transmission and a secondary antenna (diversity antenna) that may be used for signal transmission when the primary antenna has poor performance. The low noise amplifier module may be connected to the secondary antenna (e.g., because the secondary antenna is typically located farther from the transceiver circuitry than the primary antenna). 
     During step  212 , the control circuitry may determine a desired configuration of antennas for wireless communications. The desired configuration may be determined based on information received from a base station (e.g., instructions for carrier aggregation), based on detected antenna performance (e.g., whether an antenna is blocked or otherwise performing poorly), etc. In response to selecting the secondary antenna for transmitting, the operations of step  216  may be performed. In response to selecting the primary antenna for transmitting, the operations of step  214  may be performed. 
     During step  214 , the control circuitry may configure the low noise amplifier module at the secondary antenna in a first configuration that electrically couples the secondary antenna to a transceiver through a low noise amplifier. For example, switches  158 ,  156 , and  154  of  FIG. 4  may be configured to connect port  164  to port  162  via one of low noise amplifiers  152 . 
     During step  216 , the control circuitry may configure the low noise amplifier module at the secondary antenna in a second configuration that enables a transmit bypass path. For example, switches  156  and  158  of  FIG. 4  may be configured to connect port  164  to port  162  via transmit bypass path  160 . 
     During step  218 , the control circuitry may configure diversity switching circuitry (e.g., switches  122  and/or  124 ) to implement the desired antenna configuration (e.g., connecting the antennas to desired ports on transceiver circuitry  90 ). 
     During optional step  220 , the control circuitry may determine whether the current antenna configuration has potential inter-band conflicts. For example, the control circuitry may determine whether nonlinearities such as reverse intermodulation at the low noise amplifier module can cause interference between communications in different frequency bands. In response to identifying conflicts, the control circuitry may adjust the linearity of the amplifier(s) in the low noise amplifier module that are affected. For example, the control circuitry may provide a control signal to adjustable power supply voltage circuitry to provide an adjusted power supply voltage to the affected amplifiers. 
       FIG. 9  is an illustrative diagram showing how frequency multiplexing circuitry (e.g., circuitry  108  of  FIG. 3 ) may be implemented as a triplexer  108 A. As shown in  FIG. 9 , triplexer  108 A includes three filters  232 ,  234 , and  236  that are connected to a single feed point of antenna  40 T- 1 . Each filter of the triplexer may pass signals in only a predetermined range of frequencies. Filter  232  may handle WiFi signals (i.e., passes WiFi signals in a WiFi frequency band such as the 2.4 GHz band). Filter  234  may handle cellular frequencies in cellular telephone bands (e.g., LTE bands such as those in the frequency ranges between 699-960 MHz, 2300-2400 MHz, and 2496 to 2690 MHz). Filter  234  may, for example, be a notch filter with notches in its frequency response that block or otherwise prevents WiFi and GPS signals from passing between antenna  40 T- 1  and cellular circuitry. Filter  236  may handle GPS signals by passing radio-frequency signals in a GPS frequency band from antenna  40 T- 1  to LNA amplifier  112 . 
     The example of  FIG. 9  in which filters  232  and  236  are bandpass filters and filter  234  is a notch filter is merely illustrative. In general, triplexer  108 A has first, second, and third filters that pass signals in only respective radio-frequency bands. 
     If desired, multiplexing circuitry may be implemented as a quadplexer as shown in  FIG. 10 . In the example of  FIG. 10 , quadplexer  108 B has four filters FLB, FMB/HB, FGPS, and FWIFI that couple a single feed point of antenna  40 T- 1  to transceiver circuitry. Consider the scenario in which quadplexer  108 B serves as multiplexing circuitry  108  of  FIG. 3 . In this scenario, filter FLB may pass cellular low band signals from antenna  40 T- 1  to low band switching circuitry  124 , filter FMB/HB may pass mid-band and high-band signals to low noise amplifier module  52 , filter FPGS may pass GPS signals to low noise amplifier  112 , and filter FWIFI may pass WiFi signals to WiFi circuitry  106 . 
     The examples of  FIGS. 9 and 10  in which a triplexer or a quadplexer is used to separate radio-frequency signals in different frequency bands is merely illustrative. If desired, any number of filters may be combined in a multiplexing component, which may be referred to generally as an N-plexer. Use of an N-plexer (e.g., a triplexer, quadplexer, etc.) allows communications in any desired number of frequency bands to be accommodated by a single antenna. The N-plexer may therefore help to reduce the number of antennas required to support communications in multiple frequency bands (e.g., cellular, WiFi, GPS, etc.). 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20140717
Publication Date: 20160712
Grant Date: 20160712
Priority Date: 20140717
Inventors: KONG DANIEL C.
SCOLES BRADLEY D.
NOELLERT WILLIAM J.
LUM NICHOLAS W.
Assignee: APPLE INC
CPC Classifications: [{"code": "H03F2200/294", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q23/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F2200/451", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03F3/19", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q23/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F2200/294", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03F2200/451", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/401", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03F3/19", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q23/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/401", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 53783956