PATENT DOCUMENT

Publication Number: US-9698854-B2
Application Number: US-201514980574-A
Country: US
Kind Code: B2

Title: Electronic device having antenna tuning integrated circuits with sensors

Abstract:
An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. An antenna may have an antenna feed that is coupled to a radio-frequency transceiver with a transmission line. An impedance matching circuit may be coupled to the antenna feed to match the impedance of the transmission line and the antenna. The impedance matching circuit and tunable circuitry in the antenna may be formed using integrated circuits. Each integrated circuit may include switching circuitry that is used in switching components such as inductors and capacitors into use. Sensors such as temperature sensors, current and voltage sensors, power sensors, and impedance sensors may be integrated into the integrated circuits. Each integrated circuit may store settings for the switching circuitry and may include communications and control circuitry for communicating with external circuits and processing sensor data.

Claims:
What is claimed is: 
     
       1. Apparatus, comprising:
 antenna structures that transmit and receive wireless signals; 
 a tunable circuit coupled to the antenna structures to adjust the antenna structures, wherein the tunable circuit comprises:
 a plurality of electrical components; and 
 an integrated circuit comprising:
 switching circuitry that includes a plurality of switches for selecting which of the plurality of electrical components are switched into use to adjust the antenna structures; and 
 at least one sensor interposed between the plurality of switches and the plurality of electrical components. 
 
 
 
     
     
       2. The apparatus defined in  claim 1  wherein the sensor comprises a sensor selected from the group consisting of: a voltage sensor, a current sensor, a temperature sensor, a power sensor, and an impedance sensor. 
     
     
       3. The apparatus defined in  claim 1  wherein the electrical components comprise inductors. 
     
     
       4. The apparatus defined in  claim 1  wherein the electrical components comprises capacitors. 
     
     
       5. The apparatus defined in  claim 1  wherein the integrated circuit further comprises storage. 
     
     
       6. The apparatus defined in  claim 5  wherein the storage stores settings for the switching circuitry. 
     
     
       7. The apparatus defined in  claim 6  wherein the integrated circuit includes a communications interface. 
     
     
       8. The apparatus defined in  claim 7  further comprising a digital bus coupled to the communications interface. 
     
     
       9. The apparatus defined in  claim 1  further comprising:
 at least one non-linearity compensating element in the integrated circuit; and 
 control circuitry that gathers data from the sensor, wherein the control circuitry is configured to adjust the non-linearity compensating element to reduce signal harmonics based on the gathered data. 
 
     
     
       10. The apparatus defined in  claim 9  wherein the sensor comprises a temperature sensor and wherein the control circuitry adjusts the non-linearity compensating element based on temperature data from the temperature sensor. 
     
     
       11. The apparatus defined in  claim 1  wherein the sensor comprises an impedance sensor having a directional coupler and a receiver and wherein the control circuitry adjusts the switching circuitry based on impedance data from the impedance sensor. 
     
     
       12. The apparatus defined in  claim 1  wherein the antenna structures include an antenna resonating element, an antenna ground, and an antenna feed coupled to the antenna resonating element and the antenna ground, wherein the apparatus further comprises a transmission line coupled between a radio-frequency transceiver and the antenna feed, and wherein the tunable circuit comprises a tunable impedance matching circuit coupled to the antenna feed. 
     
     
       13. The apparatus defined in  claim 1  wherein the antenna structures include an antenna resonating element arm and an antenna ground configured to exhibit at least one frequency resonance and wherein the tunable circuit is coupled between an end of the antenna resonating element arm and the antenna ground and is tuned to adjust the frequency resonance. 
     
     
       14. Apparatus, comprising:
 a radio-frequency transceiver; 
 an antenna; 
 a transmission line coupled between the radio-frequency transceiver and the antenna; and 
 a tunable circuit coupled to the antenna, wherein the tunable circuit includes an integrated circuit, and wherein the integrated circuit comprises:
 switching circuitry that is adjusted to tune the tunable circuit; and 
 a plurality of sensors coupled to the switching circuitry. 
 
 
     
     
       15. The apparatus defined in  claim 14  wherein the integrated circuit further comprises control circuitry that receives sensor data from the plurality of sensors. 
     
     
       16. The apparatus defined in  claim 15  further comprising:
 a processor external to the integrated circuit; 
 a digital communications bus; and 
 a communications interface in the integrated circuit, wherein the processor receives the sensor data from the communications interface over the digital communications bus. 
 
     
     
       17. The apparatus defined in  claim 15  wherein the switching circuitry includes transistors and at least one non-linearity compensating element that compensates for non-linearity in the transistors and wherein the control circuitry adjusts the non-linearity compensating element based on the sensor data. 
     
     
       18. The apparatus defined in  claim 17  wherein the plurality of sensors comprises a temperature sensor. 
     
     
       19. The apparatus defined in  claim 17  wherein the plurality of sensors comprises current sensor that includes a current mirror and an ammeter with a digital output. 
     
     
       20. The apparatus defined in  claim 17  wherein the plurality of sensors comprises a voltage sensor with a plurality of parallel chains of transistors each coupled to a respective current sensor.

Description:
This application claims the benefit of provisional patent application No. 62/101,901 filed on Jan. 9, 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. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, the presence of conductive structures can influence antenna performance. For example, the presence of conductive housing structures or other device structures may limit the volume available for implementing antennas. This can adversely affect antenna bandwidth. Antenna tuning techniques may be used to compensate for limited antenna bandwidth, but unless a tunable antenna is operated appropriately, antenna performance may be degraded due to nonlinearities and detuning effects. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices such as improved antenna circuitry. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. An antenna may have an antenna feed that is coupled to a radio-frequency transceiver with a transmission line. An impedance matching circuit may be coupled to the antenna feed to match the impedance of the transmission line and the antenna. The antenna may also have adjustable circuitry for tuning the antenna. For example, the antenna may have a tunable circuit that is coupled between a resonating element and an antenna ground. 
     The impedance matching circuit and adjustable antenna tuning circuitry in the antenna may be formed from using integrated circuits. Each integrated circuit may include switching circuitry that is used in switching components such as inductors and capacitors into use. Sensors such as temperature sensors, current and voltage sensors, power sensors, and impedance sensors may be formed within the integrated circuits. Each integrated circuit may store settings for the switching circuitry and may include communications and control circuitry. The communications and control circuitry may be used to process sensor data and to support communications with external circuits. 
    
    
     
       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 diagram of illustrative wireless circuitry in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative antenna in accordance with an embodiment. 
         FIG. 5  is a diagram of an illustrative current sensor in accordance with an embodiment. 
         FIG. 6  is a diagram of an illustrative voltage sensor in accordance with an embodiment. 
         FIG. 7  is a diagram of an illustrative impedance sensor based on a directional coupler in accordance with an embodiment. 
         FIG. 8  is a diagram of an illustrative temperature sensor in accordance with an embodiment. 
         FIG. 9  is a diagram of an illustrative power sensor in accordance with an embodiment. 
         FIG. 10  is a diagram of an illustrative tunable antenna circuit such as a tunable impedance matching circuit in accordance with an embodiment. 
         FIG. 11  is a diagram of an illustrative tunable antenna circuit such as an antenna aperture tuner 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. Tunable circuits may be used to adjust the wireless circuitry. The tunable circuits may include one or more integrated circuits. Sensors may be incorporated into the tunable circuits. For example, sensors may be formed on the integrated circuits. Information from the sensors may be used in adjusting the tunable circuits and otherwise operating the wireless circuitry of electronic device  10 . 
     The wireless circuitry of device  10  may, for example, include a Global Position System (GPS) receiver that handles GPS satellite navigation system signals at 1575 MHz or a GLONASS receiver that handles GLONASS signals at 1609 MHz. Device  10  may also contain wireless communications circuitry that operates in communications bands such as cellular telephone bands and wireless circuitry that operates in communications bands such as the 2.4 GHz Bluetooth® band and the 2.4 GHz and 5 GHz WiFi® wireless local area network bands (sometimes referred to as IEEE 802.11 bands or wireless local area network communications bands). If desired, device  10  may also contain wireless communications circuitry for implementing near-field communications, light-based wireless communications, or other wireless communications (e.g., communications at 13.56 MHz, communications at 60 GHz, etc.). 
     Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded 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 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. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14 . Display  14  has been 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 or clear plastic. 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 . For example, housing  12  may have four peripheral edges as shown in  FIG. 1  and one or more antennas may be located along one or more of these edges. As shown in the illustrative configuration of  FIG. 1 , antennas may, if desired, be mounted in regions  20  along opposing peripheral edges of housing  12  (as an example). Antennas may also be mounted in other portions of device  10 , if desired. The configuration of  FIG. 1  is merely illustrative. 
     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 , and  42 . 
     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. 
     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 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     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). 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. Satellite navigation system signals for receiver  42  are received from a constellation of satellites orbiting the earth. 
     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). 
     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 the other antenna(s) may be 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 an optimum setting for tunable wireless circuitry associated with one or more of antennas  40 . Sensors may be incorporated into antennas  40  to gather sensor data in real time that is used in adjusting antennas  40 . 
     As shown in  FIG. 3 , transceiver circuitry  90  in wireless circuitry  34  may be coupled to antenna structures  40  using paths such as path  92 . Wireless circuitry  34  may be coupled to control circuitry  30 . Control circuitry  30  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures  40  with the ability to cover communications frequencies of interest, antenna structures  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna structures  40  may be provided with adjustable circuits such as tunable components  102  to tune antennas over communications bands of interest. Tunable components  102  may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of device  10 , control circuitry  30  may issue control signals on one or more paths such as path  88  that adjust inductance values, capacitance values, or other parameters associated with tunable components  102 , thereby tuning antenna structures  40  to cover desired communications bands. Configurations in which antennas  40  are fixed (not tunable) may also be used. 
     Path  92  may include one or more transmission lines. As an example, signal path  92  of  FIG. 3  may be a transmission line having a positive signal conductor such as line  94  and a ground signal conductor such as line  96 . Lines  94  and  96  may form parts of a coaxial cable or a microstrip transmission line (as examples). An impedance matching network (matching circuit) formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures  40  to the impedance of transmission line  92 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna structures  40 . 
     Transmission line  92  may be coupled to antenna feed structures associated with antenna structures  40 . As an example, antenna structures  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed with a positive antenna feed terminal such as terminal  98  and a ground antenna feed terminal such as ground antenna feed terminal  100 . Positive transmission line conductor  94  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  96  may be coupled to ground antenna feed terminal  92 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Tunable circuitry for an antenna may be incorporated into a tunable matching network (e.g., an adjustable impedance matching circuit coupled to feed terminals  98  and  100 ) and/or an antenna aperture tuner (e.g., tunable circuitry coupled to an antenna resonating element or other structure in an antenna that adjusts the resonant behavior of the antenna and therefore its frequency response). One or more integrated circuits may be used in implementing tunable circuits such as tunable inductors, tunable capacitors, switches for switching a desired inductor and/or capacitor into use and thereby adjusting an inductance or capacitance value for an antenna, etc. These integrated circuits may include sensors. Data from the sensors may be used in real time to determine how to make adjustments to the tunable circuits and how to make other wireless circuit adjustments. 
     Tunable circuits and sensors may be incorporated into any suitable type of antenna (patch, loop, slot, planar inverted-F, inverted-F, an antenna that includes multiple antenna structures such as these, etc.). Consider as an example, an illustrative antenna such as inverted-F antenna  40  of  FIG. 4 . As shown in  FIG. 4 , inverted-F antenna  40  has antenna resonating element  106  and antenna ground (ground plane)  104 . Antenna resonating element  106  may have a main resonating element arm such as arm  108 . The length of arm  108  may be selected so that antenna  40  resonates at desired operating frequencies. For example, the length of arm  108  may be a quarter of a wavelength at a desired operating frequency for antenna  40 . If desired, inverted-F antennas such as illustrative antenna  40  of  FIG. 4  may have more than one resonating arm branch (e.g., to create multiple frequency resonances to support operations in multiple communications bands). Antenna  40  may also exhibit resonances at harmonic frequencies. 
     Main resonating element arm  108  may be coupled to ground  104  by return path  110 . Antenna feed  112  may include positive antenna feed terminal  98  and ground antenna feed terminal  100  and may run parallel to return path  110  between arm  108  and ground  104 . Antenna  40  of  FIG. 4  may be a planar inverted-F antenna (e.g., arm  108  may have planar metal structures that run into the page in the orientation of  FIG. 4 ) or may be formed from non-planar structures. 
     Antenna  40  include tunable components  102  such as tunable impedance matching circuit  102 A and aperture tuning circuit  102 B. Circuit  102 B is coupled between arm  108  and ground  104  in the example of  FIG. 4 , but this is merely illustrative. Tunable circuits such as circuit  102 B may be coupled within arm  108 , may be interposed within return path  110 , may form part of antenna ground  104 , may be incorporated into a parasitic antenna resonating element, or may be incorporated into other antenna structures for antenna  40 . 
     Circuit  102 A and circuit  102 B may be adjusted to adjust the performance of antenna  40  during operation of device  10 . For example, the presence of an external object in the vicinity of antenna  40  may detune antenna  40 . Using circuitry such as circuitry  102 A and  102 B, antenna  40  can be adjusted to compensate for loading experienced due to the presence of the external object. Sensors such as sensors  130  and/or other sensors may be incorporated into device  10  in wireless circuitry  34  to gather information on the operating conditions of antenna  40  and device  10 . Sensors  130  may include, for example, temperature sensors for monitoring the current operating temperature of antenna  40  and device  10 , current monitoring circuitry for measuring antenna currents, voltage monitoring circuitry for monitoring antenna voltages, power monitoring circuitry for making antenna signal power measurements, and impedance measurement circuitry for making impedance measurements (e.g., impedance measurements on matching circuit  102 A, impedance measurements on antenna  40 , measurements of the impedance of a portion of antenna  40 , etc.). Sensor data from sensors  130  may be used to adjust the operation of antenna  40  (e.g., tunable circuits  102 A and  102 B), and to make other adjustments to the operation of device  10  (e.g., output power adjustments, antenna port adjustments, modulation scheme adjustments, radio access technology adjustments, etc.). With one suitable arrangement, some or all of the tunable circuitry of circuits such as circuits  102 A and  102 B may be implemented on one or more integrated circuits and sensors  130  may be implemented on these integrated circuits. By co-locating sensors  130  and the switches and other adjustable circuitry of circuits  102 A and  102 B on common integrated circuit die, space within device  10  can be conserved and local (on-chip) processing circuits may be used to help process sensor signals for making real time antenna adjustments. 
       FIG. 5  is a circuit diagram of an illustrative current sensor. As shown in  FIG. 5 , current sensor  130  may have parallel branches of transistors such as transistor branch  134  and transistor branch  136  coupled in a current mirror configuration between terminal  132  and terminal  144 . Sensor  130  may measure current I flowing between terminals  132  and  144 . Each branch of transistors may have a chain of series-connected transistors. The ratio of the sizes of the transistors in the respective branches determines the ratio of current Is to current Ib flowing in branches  134  and  136 , respectively. With one suitable arrangement, most of current I flows through main branch  136  and a small representative portion of current I flows through secondary branch  134 . The ratio of Is to Ib is known, so measurement of the magnitude of current Is can be used to determine Ib and therefore total current I. The value of current Is can be measured using digital ammeter  140  interposed within portion  138  of branch  134 . Ammeter  140  may contain an analog-to-digital converter that allows current measurements such as the values of Is, Ib, and/or I to be supplied as digital output signals on digital output path  142 . If desired, ammeter  140  or other portion of current sensor  130  may contain nonlinear circuit elements to help convert high-frequency radio-frequency antenna signals to lower frequency signals on which current measurements may be made. 
       FIG. 6  is a circuit diagram of an illustrative voltage sensor. Voltage sensor  130  of  FIG. 6  may make voltage measurements on signals applied across terminals  146  and  148 . Multiple parallel branches of transistor stacks such as branches Nh, Nm, and Nl may extend between terminals  146  and  148 . The transistors of sensor  130  may be field-effect transistors (FETs) that contain parasitic bipolar transistors and are characterized by a snap-back voltage (e.g., 3 V or other suitable voltage). Each branch of transistors may contain a different number of transistors coupled in series between terminals  146  and  148 . The number of transistors in each branch establishes a threshold voltage for current flow for that branch. Each branch of sensor  130  will conduct current when its threshold voltage has been exceeded, but will not conduct current when the voltage across terminals  146  and  148  is lower than its threshold voltage. 
     Consider, as an example, a scenario in which the transistor snap-back voltage is 3 volts and in which branches Nh, Nm, and Nl contain 15, 10, and 5 transistors, respectively. In this illustrative configuration, branch Nh will be characterized by a threshold voltage Vh of 45 volts, branch Nm will be characterized by a threshold voltage Vm of 30 volts, and branch Nl will be characterized by a threshold voltage Vl of 15 volts. A current sensor may be coupled in series with each branch. For example, current sensor AH may be coupled in series with the transistors of branch Nh, current sensor AM may be coupled in series with the transistors of branch Nm, and current sensor AL may be coupled in series with the transistors of branch Nl. Each current sensor may supply an output signal on a respective output that is indicative of whether current is flowing through that sensor. For example, current sensor AH may provide output signals on output  150 , current sensor AM may produce output signals on output  152 , and current sensor Al may produce output signals on output  154 . The signal on outputs  150 ,  152 , and  154  may be digital signals (as an example). 
     If the voltage across terminals  146  and  148  is below Vl, no current will flow through the branches of sensor  130  and outputs  150 ,  152 , and  154  will be deasserted. If the voltage across terminals  146  and  148  is between Vl and Vm, outputs  150  and  152  will be deasserted and output  154  will be asserted. When the voltage across terminals  146  and  148  exceeds Vm and is less than Vh, current sensors AM and AL will assert outputs  152  and  154 , respectively, whereas output  150  will be deasserted (indicating that no current is flowing through branch Nh). If the voltage across terminals  146  and  148  is greater than Vh, the outputs of all three current sensors (i.e., outputs  150 ,  152 , and  154  in this example) will be asserted. 
     The signals on the output path formed by outputs  150 ,  152 , and  154  serves as digital voltage measurement data for sensor  130  that is indicative of the magnitude of the voltage across voltage sensor terminals  146  and  148 . If desired, other numbers of transistors may be incorporated into each branch of sensor  130 , transistors with different snap-back voltages may be used, etc. The configuration of  FIG. 6  in which there are three parallel chains of series-connected transistors is merely illustrative. 
     Illustrative sensors  130  of  FIG. 7  may be used to make impedance measurements (e.g., complex s-parameter measurements that can be processed to produce impedance data). Impedance sensor  130  may make signal measurements on radio-frequency signals flowing on path  156  in direction  158  and direction  160 . Directional coupler  162  taps signals flowing on path  156  and provides theses signals to input ports IN of switch  164 . Switch  164  routes input signals on ports IN to output ports OUT for measurement by receiver  168 . The state of switch  164 , which can be controlled by applying control signals to control input  166 , may be adjusted depending on whether tapped signals flowing in direction  158  or direction  160  are being measured. 
     During impedance measurements, phase and magnitude measurements may be made on the signals in path  156  (e.g., transmitted and reflected signals) using directional coupler  162 , switch  164 , and receiver  168 . The output data from output  170  of receiver  168  may be processed to produce a corresponding impedance measurement. Impedance sensor  130  may be used to measure the impedance of an impedance matching circuit such as circuit  102 A of  FIG. 4  or may be used to measure impedance for antenna  40  (e.g., by incorporating impedance sensor  130  within an antenna aperture tuner circuit such as tunable circuit  102 B of  FIG. 4 ). In general, impedance sensor  130  may be used to make any suitable impedance measurement. The use of sensor  130  to measure impedance within circuits such as circuits  102 A and  102 B of  FIG. 4  is merely illustrative. 
       FIG. 8  is a diagram of an illustrative temperature sensor. As shown in  FIG. 8 , temperature sensor  130  may include a temperature sensing element such as temperature sensing element  172 . Element  172  may be based on a thermocouple structure, a temperature-sensitive resistive element, a semiconductor device such as a transistor or diode with a current that varies as a function of temperature, and/or other temperature sensing circuitry. Analog-to-digital circuitry  174  may be used to produce digital output  176  that is indicative of the magnitude of the temperature measured using temperature sensing element  172 . Temperature sensing element  172  may be used to measure the temperature of device  10  in the vicinity of sensing element  172 , may be used to measure the temperature of an integrated circuit in which sensor  130  has been implemented, may be used to measure the temperature of transistors and other circuitry that is adjacent to sensor  130 , and/or may be used in making other temperature measurements. 
       FIG. 9  is a diagram of an illustrative power sensor that may be used to make power measurements on radio-frequency signals such as antenna signals in device  10 . As shown in  FIG. 9 , power sensor  130  may be interposed within path  184 . Radio-frequency signals may flow along path  184  (e.g., to and from an antenna or other radio-frequency component, within a portion of an antenna or matching circuit, etc.). Power sensing element  178  may be coupled in path  184  and may be used to measure the power of radio-frequency signals flowing on path  184 . Power sensing element  178  may be based on a diode, may contain one or more transistors, may contain nonlinear elements, or may contain other power measuring circuitry. Analog-to-digital converter circuitry  180  may be coupled to power sensing element  178  and may convert analog power measurements made with power sensing element  178  to digital power measurement data on output  182 . 
       FIGS. 10 and 11  are circuit diagrams of illustrative impedance matching and antenna aperture tuning circuits of the type that may be used in device  10 . Illustrative locations at which sensors  130  may be incorporated into impedance matching circuit  102 A and antenna tuning circuitry  102 B are shown in  FIGS. 10 and 11 , respectively. These locations are, however, merely illustrative. Sensors  130  (e.g., current sensors, voltage sensors, temperature sensors, power sensors, impedance sensors, etc.) may be incorporated into wireless circuitry  34  at any suitable location(s). 
     In the example of  FIG. 10 , impedance matching circuit  102 A is coupled across antenna feed terminals  98  and  100  in antenna feed  112 . Antenna feed  112  is used to couple transmission line  92  to antenna  40 . Transmission line  92  may include positive signal line  94  and ground signal line  96 . Impedance matching circuit  102 A may contain components such as series and shunt inductors  186  and series and shunt capacitors  188  (as an example). Circuit  102 A may be implemented using an integrated circuit (e.g., a silicon-on-insulator integrated circuit, a silicon integrated circuit die, etc.) such as integrated circuit  189 . Components such as inductors  186  and capacitors  188  may be implemented using structures on integrated circuit  189  or may be implemented using external components that are coupled to the terminals in integrated circuit  189 . 
     Inductors  186  may be fixed inductors and/or adjustable inductors. Capacitors  188  may be fixed capacitors and/or adjustable capacitors. Other circuit components may be included in the circuitry of impedance matching circuit  102 A if desired. The example shown in  FIG. 10  in which matching circuit  102 A includes a pair of fixed inductors and a pair of tunable capacitors is merely illustrative. During operation, sensors such as sensor  130  may be used to gather sensor data (e.g., current data, voltage data, temperature data, power data, impedance data, etc.). The sensor measurements made using sensor(s)  130  may be used in adjusting tunable circuitry such as tunable matching circuit  102 A and/or other tunable antenna circuitry (see, e.g., tunable circuit  102 B of  FIG. 4 ) or may be used in making other adjustments to wireless circuitry  34  (e.g., transmit power adjustments, antenna port assignment adjustments, modulation scheme adjustments, communications frequency adjustments, etc.). As an example, real time sensor measurements made with sensor  130  in tunable matching circuit  130  may be used to determine how to make appropriate adjustments to tunable matching circuit  130  (e.g., adjustments to enhance wireless performance, adjustment to satisfy limits on transmitted power, adjustments to prevent undesired interference, etc.). Sensor  130  may be interposed in line  94  of path  92  or may be located at other portions of tunable matching circuit  102 A. 
     Matching circuit  102 A may be implemented using a semiconductor device such as a silicon integrated circuit (e.g., a silicon-on-insulator circuit, etc.). For example, circuit  102 A may include switching circuitry, control circuitry, storage (e.g., registers for storing adjustable component settings), and communications interface circuitry. Some components of circuit  102 A (e.g., discrete surface mount technology components such as SMT inductors or capacitors) may, if desired, be implemented using separate components mounted on a common printed circuit. For example, circuit  102 A may have switch ports and fixed inductors that are used in conjunction with a switch in circuit  102 A may be coupled to these switch ports. Preferably some or all of the circuitry of sensor  130  (e.g., sensing elements and/or analog-to-digital converter circuits, etc.) may be incorporated onto the same semiconductor device as the switching circuits and other integrated circuit portions of circuit  102 A. The use of a common integrated circuit to implement some or all of impedance matching circuitry  102 A and some or all of sensor  130  may help avoid unnecessary duplication of device components and may minimize space requirements for incorporating sensors into tunable circuits for wireless circuitry  34 . 
       FIG. 11  shows how tunable antenna circuit  102 B may include a semiconductor integrated circuit such as integrated circuit  196  (e.g., a silicon-on-insulator integrated circuit, a silicon integrated circuit, or an integrated circuit formed from another suitable semiconductor). In the illustrative configuration of  FIG. 11 , circuit  102 B also includes external components such as components  194 . Components  194  may be inductors (e.g., surface mount technology inductors), may be capacitors, or may be other external components that are coupled to the circuitry of integrated circuit  196  using traces on a printed circuit or other substrate. 
     Integrated circuit  196  may contain switching circuitry  206 . Switching circuitry  206  may include transistor switches  208 . Switches  208  may be formed from one or more transistors such as field-effect transistors. A circuit arrangement of the type shown in  FIG. 11  may be used to implement a tunable component such as a tunable inductor. Components  194  and switching circuitry  206  may be coupled between terminals  190  and  192 . Control circuitry may be used to supply control signals to switching circuitry  206  that direct switching circuitry  206  to switch one or more of components  194  into place between terminals  190  and  192 . In this way, the inductance (or other circuit characteristics) of circuit  102 B between terminals  190  and  192  may be adjusted in real time to tune antenna  40  or perform other adjustments to wireless circuitry  34 . Switching circuitry such as switching circuitry  206  may be used in providing components such as components  186  and  188  of  FIG. 10  with tuning capabilities (e.g., by switching internal and/or external components into use for circuit  102 A of  FIG. 10 ). 
     Sensors  130  may be incorporated into paths such as the paths between switches  208  and respective components  194 , may be incorporated into a path between switching circuitry  206  and terminal  192 , may be implemented as stand-alone sensors on the die of integrated circuit  196  (see, e.g., temperature sensor T of  FIG. 11 ), or may be incorporated elsewhere in the circuitry of integrated circuit  196 . 
     If desired, integrated circuit  196  (and integrated circuits such as integrated circuit  189  of  FIG. 10 ) may include control circuitry  200 . Control circuitry  200  may include a microcontroller or other hardwired circuitry that facilitates control operations for circuit  196  and other wireless circuitry  34 . Storage  202  (e.g., registers, blocks of memory, etc.) may be included within control circuit  200 . Storage  202  may be used to store settings for integrated circuit  196 . For example, a switch setting for switching circuitry  206  may be stored in a register in storage  202 . This register setting may be used, for example, to determine which of components  194  are switched into use. In an arrangement in which components  194  are inductors (e.g., external discrete inductors or inductors implemented as part of integrated circuit  196 ), the register setting may be used to establish a selected inductance value for circuit  102 B between terminals  190  and  192 . In an arrangement in which components  194  are capacitors, the register setting may be used to select a desired capacitance for circuit  102 B. Tunable circuit  102 B may, in general, include any suitable tunable circuits (e.g., switching circuitry  206 , inductors, capacitors, etc.) and the settings of tunable circuit  102 B may be adjusted by control circuitry  200  in real time based on settings loaded into storage  202  or based on control signals supplied to switching circuitry  206  from external control lines. 
     To facilitate communication with external control circuitry (e.g., a processor in control circuitry  30  of  FIG. 3 ), antenna tuning integrated circuit  196  (and integrated circuits such as integrated circuit  189  of  FIG. 10 ) may be provided with a communications interface such as communications interface  204 . Interface  204  may be, for example, an RFFE interface (i.e., a communications interface compliant with the MIPI® Alliance radio-frequency front end specification). Other types of serial and parallel communications interfaces may be used for interface  204  if desired. Path  210  (e.g., a digital communications bus) may be used to convey signals between interface  204  and external control circuitry in device  10  (e.g., to provide sensor data from sensors  130  to external control circuitry, to receive control signals from external control circuitry that are to be stored in storage  202 , or to otherwise support communications between integrated circuit  196  and other circuitry in device  10 ). 
     During operation, one or more sensors  130  on integrated circuit  196  may be used to gather data on the operating conditions of wireless circuitry  34 . This data may be processed locally by control circuitry  200  in integrated circuit  196  and/or may be conveyed to control circuitry elsewhere in device  10  (see, e.g., control circuitry  30  of  FIG. 2 ). Control circuitry external to integrated circuit  196  and/or control circuitry  200  within integrated circuit  196  may be used in adjusting the operation of adjustable wireless components. For example, the external and/or internal control circuitry may adjust switching circuitry  206  (e.g., switches  208 ) to switch a desired component  194  into use or to otherwise optimize performance. 
     Due to the presence of non-linear parasitics, there is a risk that wireless circuitry such as switching circuitry  206  will generate signal harmonics. Switches  208  may contain stacks of field-effect transistors. In an open-stack configuration, harmonics can arise from parasitic non-linear capacitances. In an ON state, a transistor stack may be characterized by non-linear parasitic resistances that can give rise to signal harmonics. 
     If desired, harmonics can be cancelled by appropriate adjustment of compensation circuits. For example, parasitics in a stack of field-effect transistors in a switch  208  can be compensated by appropriate adjustment of a non-linearity compensating circuit element  208 ′ in that switch  208  (e.g., a parallel stack of field-effect transistors used for non-linearity compensation). These compensating adjustments to circuit elements  208 ′ or other non-linearity compensating element may be made using data from sensors  130  (e.g., temperature data, voltage data, current data, impedance data, etc.). For example, temperature data, impedance data, current data, voltage data, power data, and other data from sensors  130  may be used to determine how to make circuit adjustments to elements  208 ′ to minimize signal harmonics. If desired, the circuit adjustments that are made based on sensor data may be used to control gate biases and body biases for field-effect transistors (e.g., stacks of field effect transistors in switches  208 , transistors in elements  208 ′, etc.). Data from sensors  130  may also be used adjusting tunable components  102  of  FIG. 3  (e.g., by adjusting switching circuitry  206 , etc.). For example, data from sensors  130  may be used to tune circuitry  102 A and/or  102 B to compensate for antenna loading effects (e.g., impedance changes due to the presence of a body part of a user or other external object in the vicinity of antenna  40 ). 
     There may, in general, be any suitable number of antenna tuner switching modules with integrated sensors in device  10  (e.g., one or more integrated circuits  196  and/or one or more integrated circuits  189 ). There may be one circuit  196  used for implementing aperture tuning circuit  102 B, there may be one circuit  189  used for implementing impedance matching circuit  102 A, both circuits  102 A and  102 B may be implemented using a pair of integrated circuits, additional integrated circuits  196  and/or  189  may be incorporated into one or more antennas  40 , 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: 20151228
Publication Date: 20170704
Grant Date: 20170704
Priority Date: 20150109
Inventors: MOW MATTHEW A.
HAN LIANG
TSAI MING-JU
BIEDKA THOMAS E.
LEE VICTOR
JUDKINS JAMES G.
PASCOLINI MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B1/40", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0442", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/40", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q3/26", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 55135557