PATENT DOCUMENT

Publication Number: US-9673916-B2
Application Number: US-201615097873-A
Country: US
Kind Code: B2

Title: Electronic device with over-the-air wireless self-testing capabilities

Abstract:
An electronic device may be provided with wireless circuitry. The wireless circuitry may include antennas. The antennas may include phased antenna arrays for handling millimeter wave signals. Antennas may be located in antenna signal paths. The antenna signal paths may include adjustable components such as adjustable filters, adjustable gain amplifiers, and adjustable phase shifters. Circuitry may be incorporated into an electronic device to facilitate wireless self-testing operations. Wireless self-testing may involve use of one antenna to transmit an over-the-air antenna test signal that is received by another antenna. The circuitry that facilitates the wireless self-testing operations may include couplers, adjustable switches for temporarily shorting antenna signal paths together, mixers for mixing down radio-frequency signals to allow digitization with analog-to-digital converters, and other circuitry for supporting self-testing operations.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 control circuitry in the housing; 
 a plurality of antennas in the housing including at least a first and second antennas in respective first and second antenna signal paths; and 
 wireless circuitry in the housing that includes transceiver circuitry that operates under control of the control circuitry to transmit and receive antenna signals over the first and second antenna signal paths using the first and second antennas, wherein the control circuitry is configured to use the wireless circuitry to transmit over-the-air antenna signals from the first antenna to the second antenna while measuring corresponding received antenna signals from the first antenna using the second antenna and transceiver circuitry in the second antenna signal path, and the control circuitry gathers impedance measurements using at least the corresponding received antenna signals. 
 
     
     
       2. The electronic device defined in  claim 1  further comprising a switch between the first antenna signal path and the second antenna signal path that the control circuitry closes to normalize path length delay between the first and second antenna signal paths. 
     
     
       3. The electronic device defined in  claim 2  further comprising an adjustable electrical component in the first antenna signal path that the control circuitry adjusts while measuring the corresponding received antenna signals from the first antenna to calibrate the adjustable electrical component. 
     
     
       4. The electronic device defined in  claim 3  wherein the adjustable electrical component comprises a phase shifter that makes phase adjustments to transmitted signals in the first antenna signal path. 
     
     
       5. The electronic device defined in  claim 3  wherein the adjustable electrical component comprises an adjustable gain amplifier that amplifies transmitted signals in the first antenna signal path. 
     
     
       6. The electronic device defined in  claim 3  wherein the adjustable electrical component comprises an adjustable filter in the first antenna signal path. 
     
     
       7. The electronic device defined in  claim 1  wherein the housing comprises a housing selected from the group consisting of: a laptop computer housing, a cellular telephone housing, and a tablet computer housing. 
     
     
       8. The electronic device defined in  claim 1  further comprising:
 a first coupler in the first antenna signal path; 
 a second coupler in the second antenna signal path; and 
 a switch that gathers signals from the first and second couplers under control of the control circuitry to make S-parameter measurements on the first and second antenna signal paths. 
 
     
     
       9. The electronic device defined in  claim 1  wherein the first and second antennas are part of a common phased antenna array. 
     
     
       10. The electronic device defined in  claim 1  wherein the first and second antennas are part of first and second different phased antenna arrays. 
     
     
       11. The electronic device defined in  claim 1  wherein the first and second antennas are located at respective first and second corners of the housing. 
     
     
       12. The electronic device defined in  claim 1  wherein the first antenna is a millimeter wave antenna. 
     
     
       13. The electronic device defined in  claim 12  wherein the second antenna is a millimeter wave antenna. 
     
     
       14. An electronic device, comprising:
 a housing 
 control circuitry in the housing; 
 a plurality of antennas in the housing including at least a first and second antennas in respective first and second antenna signal paths; 
 wireless circuitry in the housing that includes transceiver circuitry that operates under control of the control circuitry to transmit and receive antenna signals over the first and second antenna signal paths using the first and second antennas, wherein the control circuitry is configured to use the wireless circuitry to transmit over-the-air antenna signals from the first antenna to the second antenna while measuring corresponding received antenna signals from the first antenna using the second antenna and transceiver circuitry in the second antenna signal path; 
 a mixer that mixes a first signal with a second signal to produce an output; and 
 an analog-to-digital converter that digitizes the output, wherein the second signal is received from the second antenna signal path. 
 
     
     
       15. The electronic device defined in  claim 14  further comprising a radio-frequency local oscillator, wherein the first signal is received from the radio-frequency local oscillator. 
     
     
       16. The electronic device defined in  claim 14  further comprising a signal path that routes the first signal to the mixer from the first antenna signal path. 
     
     
       17. A portable electronic device, comprising:
 a housing; 
 a display in the housing; 
 a plurality of antennas in the housing including at least a first and second antennas in respective first and second antenna signal paths; and 
 wireless circuitry in the housing that transmits an over-the-air antenna test signal from the first antenna and that receives the transmitted over-the-air antenna test signal from the first antenna with the second antenna, wherein the first antenna signal path includes an adjustable electrical component that is adjusted by control circuitry while receiving the antenna test signal with the second antenna, and the control circuitry analyzes the antenna test signal received with the second antenna to produce calibration data. 
 
     
     
       18. A portable electronic device, comprising:
 a housing; 
 a plurality of phased antenna arrays in the housing, wherein the phased antenna arrays include at least first and second antennas; 
 wireless circuitry in the housing that transmits an over-the-air antenna signal from the first antenna and that receives the transmitted over-the-air antenna signal from the first antenna with the second antenna; and 
 control circuitry that tests at least the first antenna by analyzing the antenna signal received with the second antenna, wherein the phased antenna arrays comprise millimeter wave phased antenna arrays and wherein the antenna signal received with the second antenna comprises a millimeter wave antenna signal.

Description:
This application claims to benefit of provisional patent application No. 62/149,405, filed Apr. 17, 2015, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless communications circuitry. For example, cellular telephones, computers, and other devices often contain antennas and wireless transceivers for supporting wireless communications. 
     The wireless performance of an electronic device can be affected by manufacturing variations. As a result, many wireless electronic devices are tested during manufacturing. As an example, a wireless device may be placed in a test chamber to that has test antennas coupled to wireless test equipment. Tests may be performed on the wireless device while the wireless device is in the test chamber. Tests measurements such as these may be used to characterize antenna performance and to perform wireless circuit calibration. 
     It can be challenging to effectively characterize wireless electronic devices during manufacturing. Wireless devices may be produced in large volumes. Unless care is taken, the expense and complexity of installing and operating sufficient wireless test equipment to handle large volumes of devices can be prohibitive. 
     It would therefore be desirable to be able to provide improved arrangements for wirelessly testing electronic devices. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry. The electronic device may be a portable electronic device such as a cellular telephone, laptop computer, or tablet computer, or may be other electronic equipment. 
     The wireless circuitry may include antennas. The antennas may include phased antenna arrays for handling millimeter wave signals. The wireless circuitry may also include antennas of other types such as cellular telephone antennas, wireless local area network antennas, and satellite navigation system antennas. 
     Antennas may be located in antenna signal paths. The antenna signal paths may include adjustable components such as adjustable filters, adjustable gain amplifiers, and adjustable phase shifters. During operation, these adjustable components may be adjusted to implement beam steering functions and other wireless functions. 
     Circuitry may be incorporated into the wireless circuitry of an electronic device to facilitate wireless self-testing operations. Wireless self-testing may involve use of one antenna in an electronic device to transmit an over-the-air antenna signal that is received by another antenna in the electronic device. The circuitry that facilitates the wireless self-testing operations may include couplers, adjustable switches for temporarily shorting antenna signal paths together, mixers for mixing down radio-frequency signals to allow digitization with analog-to-digital converters, and other circuitry for supporting self-testing operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative electronic device showing illustrative locations at which antenna arrays for millimeter wave communications may be located in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative electronic device with wireless circuitry that distributes antenna signals to multiple antennas in accordance with an embodiment. 
         FIG. 5  is a diagram of an illustrative pair of signal paths with associated antennas that may be used in performing wireless characterization measurements such as S-parameter measurements in accordance with an embodiment. 
         FIG. 6  is a flow chart of illustrative steps involved in making S-parameter measurements using wireless circuitry of the type shown in  FIG. 5  in accordance with an embodiment. 
         FIG. 7  is a diagram of another illustrative pair of signal paths with associated antennas that may be using in performing wireless characterization measurements in accordance with an embodiment. 
         FIG. 8  is a flow chart of illustrative steps involved in performing wireless characterization measurements using wireless circuitry of the type shown in  FIG. 7  in accordance with an embodiment. 
         FIG. 9  is a flow chart of illustrative steps that may be involved in performing additional wireless characterization measurements using wireless circuitry of the type shown in  FIG. 7  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include phased antenna arrays that are used for handling millimeter wave communications. Millimeter wave communications, which are sometimes referred to as extremely high frequency (EHF) communications, involve signals at 60 GHz or other frequencies between about 10 GHz and 400 GHz. Device  10  may also contain wireless communications circuitry for handling satellite navigation system signals, cellular telephone signals, local wireless area network signals, near-field communications, light-based wireless communications, or other wireless communications. 
     Electronic device  10  may be a computing device such as a laptop computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer monitor containing an embedded computer, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     As shown in  FIG. 1 , device  10  may include a display such as display  14 . Display  14  may be mounted in a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, sapphire, or other transparent dielectric. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . An opening may also be formed in the display cover layer to accommodate ports such as a speaker port. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.). Openings in housing  12  may also be formed for audio components such as a speaker and/or a microphone. 
     Antennas may be mounted in housing  12 . To avoid disrupting communications when an external object such as a human hand or other body part of a user blocks one or more antennas, antennas may be mounted at multiple locations in housing  12 . Sensor data such as proximity sensor data, real-time antenna impedance measurements, signal quality measurements such as received signal strength information, and other data may be used in determining when an antenna (or set of antennas) is being adversely affected due to the orientation of housing  12 , blockage by a user&#39;s hand or other external object, or other environmental factors. Device  10  can then switch an antenna (or set of antennas) into use in place of the antennas that are being adversely affected. 
     Antennas may be mounted along the peripheral edges of housing  12 , on the rear of housing  12 , under the display cover glass or other dielectric display cover layer that is used in covering and protecting display  14  on the front of device  10 , under a dielectric window on a rear face of housing  12  or the edge of housing  12 , or elsewhere in device  10 . 
     A schematic diagram showing illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  30 . Storage and processing circuitry  30  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  30  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, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Storage and processing circuitry  30  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, etc. To support interactions with external equipment, storage and processing circuitry  30  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  30  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 protocols, antenna diversity protocols, satellite navigation system protocols, etc. 
     Device  10  may include input-output circuitry  44 . Input-output circuitry  44  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, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers or other components that can detect motion and device orientation relative to the Earth, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, a connector port sensor or other sensor that determines whether device  10  is mounted in a dock, and other sensors and input-output components. 
     Input-output circuitry  44  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  40 , 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 ,  42 , and  46 . 
     Transceiver circuitry  36  may be wireless local area network transceiver circuitry that may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and that may handle the 2.4 GHz Bluetooth® communications band. 
     Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (as examples). Circuitry  38  may handle voice data and non-voice data. 
     Millimeter wave transceiver circuitry  46  may support communications at extremely high frequencies (e.g., millimeter wave frequencies from 10 GHz to 400 GHz or other millimeter wave frequencies). 
     Wireless communications circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver  42  are received from a constellation of satellites orbiting the earth. 
     In satellite navigation system links, cellular telephone links, and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 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. Extremely high frequency (EHF) wireless transceiver circuitry  46  may convey signals over these over these short distances that travel between transmitter and receiver over a line-of-sight path. To enhance signal reception for millimeter wave communications, phased antenna arrays and beam steering techniques may be used. Antenna diversity schemes may also be used to ensure that the antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     Antennas  40  in wireless communications circuitry  34  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. If desired, one or more of antennas  40  may be cavity-backed antennas. 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. Dedicated antennas may be used for receiving satellite navigation system signals or, if desired, antennas  40  can be configured to receive both satellite navigation system signals and signals for other communications bands (e.g., wireless local area network signals and/or cellular telephone signals). Antennas  40  can include phased antenna arrays for handling millimeter wave communications. 
     Transmission line paths may be used to route antenna signals within device  10 . For example, transmission line paths may be used to couple antenna structures  40  to transceiver circuitry  90 . Transmission lines in device  10  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Device  10  may contain multiple antennas  40 . The antennas may be used together or one of the antennas may be switched into use while other antenna(s) are switched out of use. If desired, control circuitry  30  may be used to select an optimum antenna to use in device  10  in real time and/or to select an optimum setting for adjustable wireless circuitry associated with one or more of antennas  40 . Antenna adjustments may be made to tune antennas to perform in desired frequency ranges, to perform beam steering with a phased antenna array, and to otherwise optimize antenna performance. Sensors may be incorporated into antennas  40  to gather sensor data in real time that is used in adjusting antennas  40 . 
     In some configurations, antennas  40  may include antenna arrays. For example, the antennas that are used in handling millimeter wave signals for extremely high frequency wireless transceiver circuits  46  may be implemented as phased antenna arrays. The radiating elements in a phased antenna array for supporting millimeter wave communications may be patch antennas, dipole antennas, or other suitable antenna elements. Transceiver circuitry can be integrated with the phased antenna arrays to form integrated phased antenna array and transceiver circuit modules. 
     In devices such as handheld devices, the presence of an external object such as the hand of a user or a table or other surface on which a device is resting has a potential to block wireless signals such as millimeter wave signals or signals at other frequencies. Wireless performance can also be affected by the orientation of an antenna relative to the surroundings of device  10 . Accordingly, it may be desirable to incorporate multiple antennas within device  10 , each of which may be placed in a different location within device  10 . The antennas may be single antennas, phased antenna arrays or antenna elements within a phased antenna array, or other antennas. With this type of arrangement, control circuitry in device  10  such as control circuitry  30  may determine which antenna(s) to switch into use during operation to optimize wireless performance (e.g., to switch unblocked antennas into use, to perform beam steering operations for phased antenna arrays, etc.). 
       FIG. 3  is a perspective view of electronic device showing illustrative locations  50  in which antennas  40  (e.g., single antennas and/or phased antenna arrays for use with wireless circuitry  34  such as millimeter wave wireless transceiver circuitry  46 ) may be mounted in device  10 . As shown in  FIG. 3 , antennas  40  may be mounted at the corners of device  10 , along the edges of housing  12  such as edge  12 E, on the upper and lower portions of rear housing portion  12 R, in the center of rear housing  12  (e.g., under a dielectric window structure such as plastic logo  52 ), etc. In configurations in which housing  12  is formed from a dielectric, antennas  40  may transmit and receive antenna signals through the dielectric. In configurations in which housing  12  is formed from a conductive material such as metal, slots or other openings may be formed in the metal that are filled with plastic or other dielectric. Antennas  40  may be mounted in alignment with the dielectric (i.e., the dielectric in housing  12  may serve as one or more antenna windows for antennas  40 ). 
     Signal paths such as paths  100  of  FIG. 4  (e.g., transmission lines) may be used to distribute radio-frequency and/or intermediate frequency signals to antennas  40 . Antennas  40  may include single antennas (single band, multi-band, etc.) and/or may include antenna arrays (e.g., phased antenna arrays) for handling millimeter wave signals (i.e., radio-frequency signals at RF frequencies such as 60 GHz). If desired, paths  100  may be configured to form a ring-shaped path. The illustrative network of antenna signal distribution paths  100  that is shown in  FIG. 4  is merely illustrative. 
     Antennas  40  may be located at the corners of device housing  12  of device  10  or may be located elsewhere within device  10  as described in connection with  FIG. 3 . Transceiver circuitry  46  may be located in a central location within housing  12  (e.g., in the center of housing  12  as shown in  FIG. 4 ) or may be located in other portions of housing  12 . For example, portions of transceiver circuitry  46  may be co-located with antennas  40  (e.g., in a configuration in which each antenna array has local transceiver circuitry that communicates with a shared baseband processor). The configuration of  FIG. 4  is merely illustrative. 
     To ensure that the wireless performance of device  10  is satisfactory, device  10  may be tested. As an example, control circuitry  30  may be used to run test software that directs wireless communications circuitry  34  to transmit and receive wireless signals during testing. Some wireless signals may be conveyed to external wireless test equipment. For example, some tests for device  10  may be performed by placing device  10  in a shielded wireless test chamber. The chamber may include test antennas. Wireless test equipment that is coupled to the test antennas may be used to wirelessly communicate with device  10  (e.g., the wireless test equipment and test antennas in the test chamber may be used to perform wireless over-the-air tests on device  10 ). This type of wireless characterization procedure may be performed on representative devices  10  or on all devices  10  during manufacturing. Testing may identify faulty devices that are to be reworked or discarded and/or may be used in creating calibration data that is stored within devices  10  to calibrate devices  10 . 
     If desired, device  10  can also be wirelessly tested using over-the-air wireless test measurements that involve transmission and reception of wireless signals using only a transmitting antenna in device  10  and receiving antenna in device  10 . With this type of approach, control circuitry  30  directs wireless communications circuitry  34  to transmit test signals with a first antenna  40  while control circuitry  30  directs communications circuitry  34  to simultaneously receive the transmitted test signals with a second antenna  40 . The transmit and receive antennas of device  10  may be located at different portions of device  10  such as at different corners of housing  12  or may be located at different positions within a common antenna array (i.e., the transmit and receive antennas during a test may both be located within a common phased antenna array). In some tests, the identities of the transmit and receive antennas may be swapped (i.e., the antennas that were used as transmitting and receiving antennas may be used as receiving and transmitting antennas, respectively). Using measurements such as these, wireless circuit components such as phase shifters, filters, and amplifiers may be calibrated, antennas can be tested (e.g., to determine whether the antennas are properly coupled to their signal paths, to calibrate antenna tuning settings, etc.), and other wireless circuit measurements may be made. Examples of tests and measurements that may be performed by circuitry  30  in device  10  while transmitting antenna signals with a first antenna in device  10  and receiving the transmitted antenna signals with a second antenna in device  10  include, error vector magnitude measurements, radio-frequency bandwidth measurements, S-parameter measurements, receiver noise floor measurements, linearity, receiver blocking, etc. 
     Wireless circuitry  34  may include circuitry to facilitate loopback testing. As an example, a loopback circuit may be implemented to facilitate intermediate frequency (IF) signal quality and delay normalization measurements. If desired, an external tester may be used to calibrate a first antenna signal path (e.g., by inserting a probe into the path) before performing over-the-air tests or other wireless tests in which the first antenna signal path transmits signals that are received using a second antenna signal path. Couplers may be incorporated into the antenna signal paths of device  10  (e.g., to make S-parameter measurements). Mixing circuitry may be used to mix received radio-frequency signals down to direct-current (DC) levels suitable for digitization with analog-to-digital converter circuitry. Digitized signals can then be analyze by control circuitry  30 . 
     Using arrangements such as these or other suitable arrangements, multiple antenna signal paths in device  10  can be characterized and associated calibration data stored in device  10 . Initially a first path (and the components in that path) may be characterized. Using wireless communications between an antenna in the first path and an antenna in a second path, a second path may be calibrated using the known characteristics of the first path, and so forth, until all desired antenna signal paths in device  10  have been calibrated. 
     Consider, as an example, the illustrative configuration of  FIG. 5 . As shown in  FIG. 5 , wireless circuitry  34  in device  10  may include multiple antennas such as antennas  40 - 1  and  40 - 2 . Antennas  40 - 1  and  40 - 2  may be mounted at different corners of device housing  12 , may be part of a common phased antenna array, or may be any other two antennas in device  10 . 
     Antenna  40 - 1  may form part of antenna signal path PATH 1  and antenna  40 - 2  may form part of antenna signal path PATH 2 . Paths PATH 1  and PATH 2  may be coupled to wireless transceiver circuitry  118  (e.g., transmitter and receiver circuitry and associated baseband processor circuitry) via paths  100 . 
     Each of the antenna signal paths of  FIG. 5  may include electrical components such as output amplifiers  104 , input amplifiers  102 , phase shifters, filters, etc. Switching circuitry  107  may be coupled to ports a 1 , b 1 , a 2 , and b 2  of couplers  106  and may be configured to selectively route signals from any selected one of these ports to a desired output path  116 . Paths  116  may be coupled to paths  100  so that signals from paths  116  may be received and measured using the receivers of transceiver circuitry  118 . 
     Couplers  106  may be used to measure signals traveling in directions  112  and  114  on path PATH 1  and path PATH 2 . During testing, switching circuitry  107  may be adjusted by the control circuitry of device  10  to couple desired coupler ports to paths  116 . For example, switching circuitry  107  may be used to route signals from the coupler in PATH 1  to the receiver associated with path PATH 2  via the path  116  that is coupled to PATH 2 , so that those signals can be measured by that receiver. Using techniques such as these, S-parameter measurements can be made in wireless circuitry  34 . 
     A flow chart of illustrative steps involved in using circuitry of the type shown in  FIG. 5  to make S-parameter measurements on paths PATH 1  and PATH 2  are shown in  FIG. 6 . 
     At step  120 , the transmitter associated with path PATH 1  may be used to transmit signals through antenna  40 - 1 . While transmitting, switch  107  may be used to couple port a 1  of the coupler  106  in path PATH 1  to the receiver associated with path PATH 2 , so that the signal from port a 1  (which is proportional to the PATH 1  transmitted signal) can be measured. 
     As illustrated by wireless signals  108 , the signal that is wirelessly transmitted by path PATH 1 , is received over the air by antenna  40 - 2  in path PATH 2 . Accordingly, at step  122 , switch  107  may be configured to allow signal b 2  (which is proportional to the PATH 2  received signal) to be measured. 
     At step  124 , control circuitry  30  may compute S-parameter S 21  by calculating the ratio of measured values on ports b 2  and a 1 . 
     The S-parameter S 12  may be measured similarly. Switching circuitry  107  is first configured to allow the signal on port a 2  of the coupler in path PATH 2  to be measured using the receiver in path PATH 1  (step  126 ). The signal on port b 1  may then be measured (step  128 ). At step  130 , the ratio of the measured signals on ports b 1  and a 2  may be computed to determine S-parameter S 12 . As indicated by step  132 , additional S-parameter measurements can be made in the same fashion (e.g., by transmitting signals on one antenna while receiving signals with another antenna). If desired, all antenna signal paths in device  10  may be characterized using this type of self-testing scheme, thereby minimizing the use of external test equipment. 
     Another illustrative configuration for wireless circuitry  34  is shown in  FIG. 7 . In the example of  FIG. 7 , baseband processor  140  is used to generate (and receive) antenna signals at intermediate frequencies IF. Paths  100  may be used to convey intermediate frequency signals IF or other antenna signals between baseband processor  140  and antenna signal paths (e.g., antenna signal paths in integrated circuit  190  or other wireless circuitry  34 ). Control signals (e.g., signals from baseband processor  140  or other control circuitry  30  and/or direct-current power signals) may also be distributed using paths  100 . 
     Each signal path may include an associated antenna. For example, PATH 1  may include antenna  40 - 1  and PATH 2  may include antenna  40 - 2 . Transceiver circuitry  118 - 1  and  118 - 2  may include transmitter and receiver circuits and upconverters  142  and downconverters  144 . Upconverters  142  may convert IF signals to radio-frequency (RF) signals at higher frequencies. Downconverters  144  may convert RF signals to IF signals at lower frequencies. Path PATH 1  may include circuits such as filters F 1  and F 1  (e.g., adjustable channel filters to block out-of-band signals), adjustable phase shifter P 1 , adjustable gain output amplifier A 1 , and input amplifier A 1 ′. Path PATH 2  may include circuits such as channel filters F 2  and F 2 ′, adjustable phase shifter P 2 , adjustable gain amplifier A 2 , and amplifier A 2 ′. In some embodiments, a switch such as switch  146  may be coupled between paths PATH 1  and PATH 2 . To measure signals on one of the antenna paths (e.g., PATH 2 ), signals may be tapped from that path (see, e.g., signal path  154 ) that are downconverted to direct-current (DC) frequencies by mixing these tapped signals with signals from radio-frequency local oscillator  148  using mixer  150  and digitizing these signals for analysis by control circuitry  30  using analog-to-digital converter  152 . As an alternative, mixer  150 ′ may mix signals from path  154  with signals from path  156  (e.g., signals tapped from another antenna signal path such as PATH 1 ) and may digitize these signals for control circuitry  30  using analog-to-digital converter  152 ′. 
     A flow chart of illustrative steps involved in using wireless circuitry  34  of the type shown in  FIG. 7  to perform wireless self-test measurements is shown in  FIG. 8 . As shown in  FIG. 8 , a signal such as a modulated test signal may be transmitted on path PATH 1  at step  170 . The transmitted signal may be transmitted over the air as over-the-air antenna signal  108  by antenna  40 - 1  and received by antenna  40 - 2  in PATH 2  (step  172 ). At step  174 , the received signal on path PATH 2  may be mixed to DC with mixer  150  or  150 ′ and converted to digital using analog-to-digital converter  152  or  152 ′. 
     As shown in  FIG. 7 , the portion of wireless circuitry  34  associated with paths PATH 1  and PATH 2  may be implemented on one or more integrated circuits such as antenna integrated circuit  190 . If desired, test results information may be conveyed from integrated circuit  190  to control circuitry  30  using intermediate frequency (IF) signal paths such as paths  100 . The received data may be analyzed using control circuitry  30  at step  178 . For example, control circuitry  30  may determine bit error rates and may otherwise evaluate the performance of wireless circuitry  34 . If desired, this process may be repeated (i.e., all of the antenna signal paths in circuitry  34  can be tested in a step-by-step fashion leveraging previously calibrated paths), as indicated by step  180  (in which a new antenna signal path for testing is selected) and line  182 . 
     A flow chart of illustrative steps involved in using wireless circuitry  34  of  FIG. 7  to perform additional wireless self-test measurements is shown in  FIG. 9 . In the example of  FIG. 9 , switch  146  of  FIG. 7  is closed and opened. Initially, at step  184 , control circuitry  30  normalizes the path length delay between paths PATH 1  and PATH 2  by closing switch SW. In particular, the upconverter  142  of path PATH 1  is used to supply a continuous wave (CW) radio-frequency output signal over frequencies in a frequency band of interest to path PATH 1  while switch SW is turned on to short path PATH 1  to path PATH 2 . Phase shifter P 2  (and other circuit components such as adjustable filters and amplifiers) may be left in a default setting (as an example). At the same time, the downconverter  144  of PATH 2  is used by circuitry  30  to measure the magnitude and phase of signals received at transceiver  118 - 2 . The magnitude and phase information that is measured by transceiver  118 - 2  in this way may be stored by control circuitry  30  (e.g., baseband processor  140  or other control circuitry in device  10 ) and used to define a zero state for each of the frequencies in the band of interest. 
     At step  186 , calibration operations are performed using the known zero state. In particular, control circuitry  30  may open switch SW to force transmitted signals on PATH 1  to be conveyed between PATH 1  and PATH 2  as over-the-air antenna signals  108  that pass from antenna  40 - 1  to antenna  40 - 2 . While these signals are being transmitted by the transmitter in transceiver circuit  118 - 1  on PATH 1  and received by the receiver in transceiver circuit  118 - 2  on PATH 2 , the components of PATH 1  (phase shifter, adjustable gain amplifier, channel filter, etc.) may be adjusted to calibrate these components. As an example, the phase shift setting of phase shifter P 1  may be adjusted from its default setting (e.g., 0°) through a full range of phase shifts (e.g., through a full 360° or more in phase). The resulting phase and magnitude of the received signals on PATH 2  may be measured using the downconverter  144  and receiver of transceiver circuit  118 - 2 ). In this way, control circuitry  30  (e.g., baseband processor  14 ) may collect calibration data for phase shifter P 1  (e.g., data that indicates how much phase shift is produced in path PATH 2  for a given change in the setting of phase shifter P 1  in PATH 1 ). The calibration data may be stored in device  10  and, if desired, may be used to calibrate other devices  10  that include circuitry  34  (e.g., other devices  10  of the same type as device  10  that are being manufactured using the same type of components). 
     As indicated by step  188 , additional antenna signal paths (and, if desired, additional components such as adjustable gain amplifiers, channel filters, etc.) may be calibrated by repeating the operations of steps  184  and  186  on additional antenna signal paths in a stepwise fashion. 
     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: 20160413
Publication Date: 20170606
Grant Date: 20170606
Priority Date: 20150417
Inventors: MOW MATTHEW A.
NOORI BASIM
OUYANG YUEHUI
JIANG YI
PASCOLINI MATTIA
CABALLERO RUBEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B17/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B17/19", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/19", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B17/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B17/19", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 57129291