This disclosure relates generally to electronic devices and, more particularly, to electronic devices with wireless circuitry.
Electronic devices are often provided with wireless capabilities. An electronic device with wireless capabilities has wireless circuitry that includes one or more antennas. The wireless circuitry is used to perform communications using radio-frequency signals conveyed by the antennas.
As software applications on electronic devices become more data-intensive over time, demand has grown for electronic devices that support wireless communications at higher data rates. However, the maximum data rate supported by electronic devices is limited by the frequency of the radio-frequency signals. In addition, it can be difficult to provide wireless circuitry that supports these frequencies without consuming an excessive amount of area and resources on the device.
An electronic device may include wireless circuitry with light sources that generate at least a first optical local oscillator (LO) signal and a second optical LO signal. The wireless circuitry may include a phased antenna array. The phased antenna array may include antennas arranged in rows and columns or in other patterns. The antennas may include photodiodes, antenna radiating elements coupled to the photodiodes, and optical couplers coupled to the photodiodes. One of the optical LO signals may be modulated with wireless data during signal transmission if desired.
First optical paths may be coupled to each row of the array. Second optical paths may be coupled to each column of the array. First optical phase shifters may be disposed on the first optical paths. Second optical phase shifters may be disposed on the second optical paths. The first optical phase shifters may apply respective phase shifts to the first optical LO signal to produce phase-shifted signals provided to each row of the array. The second optical phase shifters may apply respective phase shifts to the second optical LO signal to produce phase-shifted signals provided to each column of the array. Each photodiode may convey wireless signals at a frequency greater than 100 GHz using its corresponding antenna radiating element based on the phase-shifted signals provided to its row and column. The phase shifts provided across the rows and the phase shifts provided across the columns may control the array to convey the wireless signals within a signal beam oriented in a selected beam pointing direction. By sharing optical phase shifters across rows and columns of the array, the array may perform three-dimensional signal beam steering while minimizing the number of optical phase shifters required by the wireless circuitry.
An aspect of the disclosure provides an electronic device. The electronic device may include a first light source configured to generate a first optical local oscillator (LO) signal. The electronic device may include a second light source configured to generate a second optical LO signal. The electronic device may include an array of antennas arranged in rows and columns, each antenna in the array including a respective photodiode coupled to a respective antenna radiating element. The electronic device may include first optical paths coupled to the rows of the array. The electronic device may include second optical paths coupled to the columns of the array. The electronic device may include first optical phase shifters disposed on the first optical paths and configured to output phase-shifted versions of the first optical LO signal on the first optical paths. The electronic device may include second optical phase shifters disposed on the second optical paths and configured to output phase-shifted versions of the second optical LO signal on the second optical paths, the photodiodes in the array being configured to convey wireless signals using the antenna radiating elements based on the phase-shifted versions of the first optical LO signals and the phase-shifted versions of the second optical LO signals.
An aspect of the disclosure provides a method of wireless communication via an electronic device having an array of antennas arranged in rows and columns, the antennas having photodiodes and antenna radiating elements coupled to the photodiodes. The method can include receiving, at the photodiodes in the antennas of each row in the array, a respective phase-shifted version of a first optical local oscillator (LO) signal. The method can include receiving, at the photodiodes in the antennas of each column of the array, a respective phase-shifted version of a second optical LO signal. The method can include transmitting, via the antenna radiating elements, wireless signals based on the phase-shifted versions of the first optical LO signal and the phase-shifted versions of the second optical LO signal.
An aspect of the disclosure provides an electronic device. The electronic device can include a first antenna having a first photodiode, a first antenna radiating element coupled to the first photodiode, and a first optical coupler coupled to the first photodiode. The electronic device can include a second antenna having a second photodiode, a second antenna radiating element coupled to the second photodiode, and a second optical coupler coupled to the second photodiode. The electronic device can include a first optical path coupled to the first optical coupler and the second optical coupler. The electronic device can include a first optical phase shifter configured to generate a first phase-shifted signal on the first optical path by applying a first optical phase shift to a first optical local oscillator (LO) signal, the first photodiode being configured to transmit first wireless signals using the first antenna radiating element based at least on the first phase-shifted signal, and the second photodiode being configured to transmit second wireless signals using the second antenna radiating element based at least on the first phase-shifted signal.
Electronic device 10 of
As shown in the functional block diagram of
Device 10 may include control circuitry 14. Control circuitry 14 may include storage such as storage circuitry 16. Storage circuitry 16 may include 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. Storage circuitry 16 may include storage that is integrated within device 10 and/or removable storage media.
Control circuitry 14 may include processing circuitry such as processing circuitry 18. Processing circuitry 18 may be used to control the operation of device 10. Processing circuitry 18 may include on one or more processors, microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), graphics processing units (GPUs), etc. Control circuitry 14 may be configured to perform operations in device 10 using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device 10 may be stored on storage circuitry 16 (e.g., storage circuitry 16 may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry 16 may be executed by processing circuitry 18.
Control circuitry 14 may be used to run software on device 10 such as satellite navigation applications, 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, control circuitry 14 may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry 14 include internet protocols, wireless local area network (WLAN) protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols (e.g., ultra-wideband protocols), cellular telephone protocols (e.g., 3G protocols, 4G (LTE) protocols, 3GPP Fifth Generation (5G) New Radio (NR) protocols, Sixth Generation (6G) protocols, sub-THz protocols, THz protocols, etc.), antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), antenna-based spatial ranging protocols, optical communications protocols, or any other desired communications protocols. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol.
Device 10 may include input-output circuitry 20. Input-output circuitry 20 may include input-output devices 22. Input-output devices 22 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 22 may include user interface devices, data port devices, and other input-output components. For example, input-output devices 22 may include touch sensors, displays (e.g., touch-sensitive and/or force-sensitive displays), light-emitting components such as displays without touch sensor capabilities, buttons (mechanical, capacitive, optical, etc.), scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, audio jacks and other audio port components, digital data port devices, motion sensors (accelerometers, gyroscopes, and/or compasses that detect motion), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), temperature sensors, etc. In some configurations, keyboards, headphones, displays, pointing devices such as trackpads, mice, and joysticks, and other input-output devices may be coupled to device 10 using wired or wireless connections (e.g., some of input-output devices 22 may be peripherals that are coupled to a main processing unit or other portion of device 10 via a wired or wireless link).
Input-output circuitry 20 may include wireless circuitry 24 to support wireless communications. Wireless circuitry 24 (sometimes referred to herein as wireless communications circuitry 24) may include one or more antennas 30.
Wireless circuitry 24 may also include transceiver circuitry 26. Transceiver circuitry 26 may include transmitter circuitry, receiver circuitry, modulator circuitry, demodulator circuitry (e.g., one or more modems), radio-frequency circuitry, one or more radios, intermediate frequency circuitry, optical transmitter circuitry, optical receiver circuitry, optical light sources, other optical components, baseband circuitry (e.g., one or more baseband processors), amplifier circuitry, clocking circuitry such as one or more local oscillators and/or phase-locked loops, memory, one or more registers, filter circuitry, switching circuitry, analog-to-digital converter (ADC) circuitry, digital-to-analog converter (DAC) circuitry, radio-frequency transmission lines, optical fibers, and/or any other circuitry for transmitting and/or receiving wireless signals using antennas 30. The components of transceiver circuitry 26 may be implemented on one integrated circuit, chip, system-on-chip (SOC), die, printed circuit board, substrate, or package, or the components of transceiver circuitry 26 may be distributed across two or more integrated circuits, chips, SOCs, printed circuit boards, substrates, and/or packages.
The example of
Transceiver circuitry 26 may be coupled to each antenna 30 in wireless circuitry 24 over a respective signal path 28. Each signal path 28 may include one or more radio-frequency transmission lines, waveguides, optical fibers, and/or any other desired lines/paths for conveying wireless signals between transceiver circuitry 26 and antenna 30. Antennas 30 may be formed using any desired antenna structures for conveying wireless signals. For example, antennas 30 may include antennas with resonating elements that are formed from dipole antenna structures, planar dipole antenna structures (e.g., bowtie antenna structures), slot antenna structures, loop antenna structures, patch antenna structures, inverted-F antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antennas, dipoles, hybrids of these designs, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and/or other antenna tuning components may be adjusted to adjust the frequency response and wireless performance of antennas 30 over time.
If desired, two or more of antennas 30 may be integrated into a phased antenna array (sometimes referred to herein as a phased array antenna) in which each of the antennas conveys wireless signals with a respective phase and magnitude that is adjusted over time so the wireless signals constructively and destructively interfere to produce (form) a signal beam in a given pointing direction. The term “convey wireless signals” as used herein means the transmission and/or reception of the wireless signals (e.g., for performing unidirectional and/or bidirectional wireless communications with external wireless communications equipment). Antennas 30 may transmit the wireless signals by radiating the signals into free space (or to free space through intervening device structures such as a dielectric cover layer). Antennas 30 may additionally or alternatively receive the wireless signals from free space (e.g., through intervening devices structures such as a dielectric cover layer). The transmission and reception of wireless signals by antennas 30 each involve the excitation or resonance of antenna currents on an antenna resonating (radiating) element in the antenna by the wireless signals within the frequency band(s) of operation of the antenna.
Transceiver circuitry 26 may use antenna(s) 30 to transmit and/or receive wireless signals that convey wireless communications data between device 10 and external wireless communications equipment (e.g., one or more other devices such as device 10, a wireless access point or base station, etc.). The wireless communications data may be conveyed bidirectionally or unidirectionally. The wireless communications data may, for example, include data that has been encoded into corresponding data packets such as wireless data associated with a telephone call, streaming media content, internet browsing, wireless data associated with software applications running on device 10, email messages, etc.
Additionally or alternatively, wireless circuitry 24 may use antenna(s) 30 to perform wireless sensing operations. The sensing operations may allow device 10 to detect (e.g., sense or identify) the presence, location, orientation, and/or velocity (motion) of objects external to device 10. Control circuitry 14 may use the detected presence, location, orientation, and/or velocity of the external objects to perform any desired device operations. As examples, control circuitry 14 may use the detected presence, location, orientation, and/or velocity of the external objects to identify a corresponding user input for one or more software applications running on device 10 such as a gesture input performed by the user's hand(s) or other body parts or performed by an external stylus, gaming controller, head-mounted device, or other peripheral devices or accessories, to determine when one or more antennas 30 needs to be disabled or provided with a reduced maximum transmit power level (e.g., for satisfying regulatory limits on radio-frequency exposure), to determine how to steer (form) a radio-frequency signal beam produced by antennas 30 for wireless circuitry 24 (e.g., in scenarios where antennas 30 include a phased array of antennas 30), to map or model the environment around device 10 (e.g., to produce a software model of the room where device 10 is located for use by an augmented reality application, gaming application, map application, home design application, engineering application, etc.), to detect the presence of obstacles in the vicinity of (e.g., around) device 10 or in the direction of motion of the user of device 10, etc.
Wireless circuitry 24 may transmit and/or receive wireless signals within corresponding frequency bands of the electromagnetic spectrum (sometimes referred to herein as communications bands or simply as “bands”). The frequency bands handled by communications circuitry 26 may include wireless local area network (WLAN) frequency bands (e.g., Wi-Fi® (IEEE 802.11) or other WLAN communications bands) such as a 2.4 GHz WLAN band (e.g., from 2400 to 2480 MHz), a 5 GHz WLAN band (e.g., from 5180 to 5825 MHz), a Wi-Fi® 6E band (e.g., from 5925-7125 MHz), and/or other Wi-Fi® bands (e.g., from 1875-5160 MHz), wireless personal area network (WPAN) frequency bands such as the 2.4 GHz Bluetooth® band or other WPAN communications bands, cellular telephone frequency bands (e.g., bands from about 600 MHz to about 5 GHz, 3G bands, 4G LTE bands, 5G New Radio Frequency Range 1 (FR1) bands below 10 GHz, 5G New Radio Frequency Range 2 (FR2) bands between 20 and 60 GHz, etc.), other centimeter or millimeter wave frequency bands between 10-100 GHz, near-field communications frequency bands (e.g., at 13.56 MHz), satellite navigation frequency bands (e.g., a GPS band from 1565 to 1610 MHz, a Global Navigation Satellite System (GLONASS) band, a BeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband (UWB) frequency bands that operate under the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols, communications bands under the family of 3GPP wireless communications standards, communications bands under the IEEE 802.XX family of standards, and/or any other desired frequency bands of interest.
Over time, software applications on electronic devices such as device 10 have become more and more data intensive. Wireless circuitry on the electronic devices therefore needs to support data transfer at higher and higher data rates. In general, the data rates supported by the wireless circuitry are proportional to the frequency of the wireless signals conveyed by the wireless circuitry (e.g., higher frequencies can support higher data rates than lower frequencies). Wireless circuitry 24 may convey centimeter and millimeter wave signals to support relatively high data rates (e.g., because centimeter and millimeter wave signals are at relatively high frequencies between around 10 GHz and 100 GHz). However, the data rates supported by centimeter and millimeter wave signals may still be insufficient to meet all the data transfer needs of device 10. To support even higher data rates such as data rates up to 5-10 Gbps or higher, wireless circuitry 24 may convey wireless signals at frequencies greater than 100 GHz.
As shown in
Space is at a premium within electronic devices such as device 10. In some scenarios, different antennas 30 are used to transmit THF signals 32 than are used to receive THF signals 34. However, handling transmission of THF signals 32 and reception of THF signals 34 using different antennas 30 can consume an excessive amount of space and other resources within device 10 because two antennas 30 and signal paths 28 would be required to handle both transmission and reception. To minimize space and resource consumption within device 10, the same antenna 30 and signal path 28 may be used to both transmit THF signals 32 and to receive THF signals 34. If desired, multiple antennas 30 in wireless circuitry 24 may transmit THF signals 32 and may receive THF signals 34. The antennas may be integrated into a phased antenna array that transmits THF signals 32 and that receives THF signals 34 within a corresponding signal beam oriented in a selected beam pointing direction.
It can be challenging to incorporate components into wireless circuitry 24 that support wireless communications at these high frequencies. If desired, transceiver circuitry 26 and signal paths 28 may include optical components that convey optical signals to support the transmission of THF signals 32 and the reception of THF signals 34 in a space and resource-efficient manner. The optical signals may be used in transmitting THF signals 32 at THF frequencies and in receiving THF signals 34 at THF frequencies.
As shown in
UTC PD 42 may have a bias terminal 38 that receives one or more control signals VBIAS. Control signals VBIAS may include bias voltages provided at one or more voltage levels and/or other control signals for controlling the operation of UTC PD 42 such as impedance adjustment control signals for adjusting the output impedance of UTC PD 42. Control circuitry 14 (
As shown in
During signal transmission, wireless data (e.g., wireless data packets, symbols, frames, etc.) may be modulated onto optical local oscillator signal LO2 to produce modulated optical local oscillator signal LO2′. If desired, optical local oscillator signal LO1 may be provided with an optical phase shift S. Optical path 40 may illuminate UTC PD 42 with optical local oscillator signal LO1 (plus the optical phase shift S when applied) and modulated optical local oscillator signal LO2′. If desired, lenses or other optical components may be interposed between optical path 40 and UTC PD 42 to help focus the optical local oscillator signals onto UTC PD 42.
UTC PD 42 may convert optical local oscillator signal LO1 and modulated local oscillator signal LO2′ (e.g., beats between the two optical local oscillator signals) into antenna currents that run along the perimeter of radiating element arms 36. The frequency of the antenna currents is equal to the frequency difference between local oscillator signal LO1 and modulated local oscillator signal LO2′. The antenna currents may radiate (transmit) THF signals 32 into free space. Control signal VBIAS may control UTC PD 42 to convert the optical local oscillator signals into antenna currents on radiating element arms 36 while preserving the modulation and thus the wireless data on modulated local oscillator signal LO2′ (e.g., by applying a squaring function to the signals). THF signals 32 will thereby carry the modulated wireless data for reception and demodulation by external wireless communications equipment.
The frequency of intermediate frequency signals SIGIF may be equal to the frequency of THF signals 34 minus the difference between the frequency of optical local oscillator signal LO1 and the frequency of optical local oscillator signal LO2. As an example, intermediate frequency signals SIGIF may be at lower frequencies than THF signals 32 and 34 such as centimeter or millimeter wave frequencies between 10 GHz and 100 GHz, between 30 GHz and 80 GHz, around 60 GHz, etc. If desired, transceiver circuitry 26 (
The antenna 30 of
As shown in
To minimize space within device 10, antenna 30V may be vertically stacked over or under antenna 30H (e.g., where UTC PD 42V partially or completely overlaps UTC PD 42H). In this example, antennas 30V and 30H may both be formed on the same substrate such as a rigid or flexible printed circuit board. The substrate may include multiple stacked dielectric layers (e.g., layers of ceramic, epoxy, flexible printed circuit board material, rigid printed circuit board material, etc.). The radiating element arms 36 in antenna 30V may be formed on a separate layer of the substrate than the radiating element arms 36 in antenna 30H or the radiating element arms 36 in antenna 30V may be formed on the same layer of the substrate as the radiating element arms 36 in antenna 30H. UTC PD 42V may be formed on the same layer of the substrate as UTC PD 4211 or UTC PD 42V may be formed on a separate layer of the substrate than UTC PD 42H. UTC PD 42V may be formed on the same layer of the substrate as the radiating element arms 36 in antenna 30V or may be formed on a separate layer of the substrate as the radiating element arms 36 in antenna 30V. UTC PD 42H may be formed on the same layer of the substrate as the radiating element arms 36 in antenna 30H or may be formed on a separate layer of the substrate as the radiating element arms 36 in antenna 30H.
If desired, antennas 30 or antennas 30H and 30V of
Phased antenna array 46 may occupy relatively little space within device 10. For example, each antenna 30V/30H may have a length 48 (e.g., as measured from the end of one radiating element arm to the opposing end of the opposite radiating element arm). Length 48 may be approximately equal to one-half the wavelength of THF signals 32 and 34. For example, length 48 may be as small as 0.5 mm or less. Each UTC-PD 42 in phased antenna array 46 may occupy a lateral area of 100 square microns or less. This may allow phased antenna array 46 to occupy very little area within device 10, thereby allowing the phased antenna array to be integrated within different portions of device 10 while still allowing other space for device components. The examples of
As shown in
Signal path 28 may include an optical splitter such as optical splitter (OS) 54, optical paths such as optical path 64 and optical path 62, an optical combiner such as optical combiner (OC) 52, and optical path 40. Optical path 62 may be an optical fiber or waveguide. Optical path 64 may be an optical fiber or waveguide. Optical splitter 54 may have a first (e.g., input) port coupled to optical path 66, a second (e.g., output) port coupled to optical path 62, and a third (e.g., output) port coupled to optical path 64. Optical path 64 may couple optical splitter 54 to a first (e.g., input) port of optical combiner 52. Optical path 62 may couple optical splitter 54 to a second (e.g., input) port of optical combiner 52. Optical combiner 52 may have a third (e.g., output) port coupled to optical path 40.
An optical phase shifter such as optical phase shifter 80 may be (optically) interposed on or along optical path 64. An optical modulator such as optical modulator 56 may be (optically) interposed on or along optical path 62. Optical modulator 56 may be, for example, a Mach-Zehnder modulator (MZM) and may therefore sometimes be referred to herein as MZM 56. MZM 56 includes a first optical arm (branch) 60 and a second optical arm (branch) 58 interposed in parallel along optical path 62. Propagating optical local oscillator signal LO2 along arms 60 and 58 of MZM 56 may, in the presence of a voltage signal applied to one or both arms, allow different optical phase shifts to be imparted on each arm before recombining the signal at the output of the MZM (e.g., where optical phase modulations produced on the arms are converted to intensity modulations at the output of MZM 56). When the voltage applied to MZM 56 includes wireless data, MZM 56 may modulate the wireless data onto optical local oscillator signal LO2. If desired, the phase shifting performed at MZM 56 may be used to perform beam forming/steering in addition to or instead of optical phase shifter 80. MZM 56 may receive one or more bias voltages WBIAS (sometimes referred to herein as bias signals WBIAS) applied to one or both of arms 58 and 60. Control circuitry 14 (
Intermediate frequency signal path 44 may couple UTC PD 42 to MZM 56 (e.g., arm 60). An amplifier such as low noise amplifier 82 may be interposed on intermediate frequency signal path 44. Intermediate frequency signal path 44 may be used to pass intermediate frequency signals SIGIF from UTC PD 42 to MZM 56. DAC 74 may have an input coupled to up-conversion circuitry, modulator circuitry, and/or baseband circuitry in a transmitter of transceiver circuitry 26. DAC 74 may receive digital data to transmit over antenna 30 and may convert the digital data to the analog domain (e.g., as data DAT). DAC 74 may have an output coupled to transmit data path 78. Transmit data path 78 may couple DAC 74 to MZM 56 (e.g., arm 60). Each of the components along signal path 28 may allow the same antenna 30 to both transmit TI-IF signals 32 and receive TI-IF signals 34 (e.g., using the same components along signal path 28), thereby minimizing space and resource consumption within device 10.
LO light sources 70 may produce (emit) optical local oscillator signals LO1 and LO2 (e.g., at different wavelengths that are separated by the wavelength of THF signals 32/34). Optical components 68 may include lenses, waveguides, optical couplers, optical fibers, and/or other optical components that direct the emitted optical local oscillator signals LO1 and LO2 towards optical splitter 54 via optical path 66. Optical splitter 54 may split the optical signals on optical path 66 (e.g., by wavelength) to output optical local oscillator signal LO1 onto optical path 64 while outputting optical local oscillator signal LO2 onto optical path 62.
Control circuitry 14 (
During transmission of THF signals 32, DAC 74 may receive digital wireless data (e.g., data packets, frames, symbols, etc.) for transmission over THF signals 32. DAC 74 may convert the digital wireless data to the analog domain and may output (transmit) the data onto transmit data path 78 as data DAT (e.g., for transmission via antenna 30). Power amplifier 76 may amplify data DAT. Transmit data path 78 may pass data DAT to MZM 56 (e.g., arm 60). MZM 56 may modulate data DAT onto optical local oscillator signal LO2 to produce modulated optical local oscillator signal LO2′ (e.g., an optical local oscillator signal at the frequency/wavelength of optical local oscillator signal LO2 but that is modulated to include the data identified by data DAT). Optical combiner 52 may combine optical local oscillator signal LO1 with modulated optical local oscillator signal LO2′ at optical path 40.
Optical path 40 may illuminate UTC PD 42 with (using) optical local oscillator signal LO1 (e.g., with the phase shift S applied by optical phase shifter 80) and modulated optical local oscillator signal LO2′. Control circuitry 14 (
During reception of THF signals 34, MZM 56 does not modulate any data onto optical local oscillator signal LO2. Optical path 40 therefore illuminates UTC PD 42 with optical local oscillator signal LO1 (e.g., with phase shift S) and optical local oscillator signal LO2. Control circuitry 14 (
The example of
As shown in
Optical components 68 may include LO light sources 70 such as a first LO light source 70A and a second LO light source 70B. The optical signal paths for each of the antennas 30 in phased antenna array 88 may share one or more optical splitters 54 such as a first optical splitter 54A and a second optical splitter 54B. LO light source 70A may generate (e.g., produce, emit, transmit, etc.) first optical local oscillator signal LO1 and may provide first optical local oscillator signal LO1 to optical splitter 54A via optical path 66A. Optical splitter 54A may distribute first optical local oscillator signal LO1 to each of the UTC PDs 42 in phased antenna array 88 over optical paths 64 (e.g., optical paths 64-0, 64-1, 64-(N−1), etc.). Similarly, LO light source 70B may generate (e.g., produce, emit, transmit, etc.) second optical local oscillator signal LO2 and may provide second optical local oscillator signal LO2 to optical splitter 54B via optical path 66B. Optical splitter 54B may distribute second optical local oscillator signal LO2 to each of the UTC PDs 42 in phased antenna array 88 over optical paths 62 (e.g., optical paths 62-0, 62-1, 62-(N−1), etc.).
A respective optical phase shifter 80 may be interposed along (on) each optical path 64 (e.g., a first optical phase shifter 80-0 may be interposed along optical path 64-0, a second optical phase shifter 80-1 may be interposed along optical path 64-1, an Nth optical phase shifter 80-(N−1) may be interposed along optical path 64-(N−1), etc.). Each optical phase shifter 80 may receive a control signal CTRL that controls the phase S provided to optical local oscillator signal LO1 by that optical phase shifter (e.g., first optical phase shifter 80-0 may impart an optical phase shift of zero degrees/radians to the optical local oscillator signal LO1 provided to antenna 30-0, second optical phase shifter 80-1 may impart an optical phase shift of Δϕ to the optical local oscillator signal LO1 provided to antenna 30-1, Nth optical phase shifter 80-(N−1) may impart an optical phase shift of (N−1)Δϕ to the optical local oscillator signal LO1 provided to antenna 30-(N−1), etc.). By adjusting the phase S imparted by each of the N optical phase shifters 80, control circuitry 14 (
In the example of
First consider a single isotropic radiator (e.g., antenna 30). Such a radiator has a radiated field that is proportional to exp(j*k*r)/(4π*r). Hence, the radiation intensity associated with the radiator is constant (isotropic). The unnormalized array factor (AF) of such a radiator is AF=1. Now consider a one-dimensional phased antenna array having a single row of W antennas (e.g., antennas 30) that receive a plane wave incident at an angle θ relative to the plane of the array. Each element in the array (each antenna) is excited with a signal at a given amplitude (e.g., 1), but because the transmission paths between elements are not equal, the phase shift of each element will be different. As such, the array factor for such an arrangement is equal to AF=exp(j*ξ0)+exp(j*ξ1)+exp(j*ξ2)+ . . . +exp(j*ξW), where ξi is the phase of an incoming plane wave at each respective (e.g., ith) element (e.g., references to some point such as the origin) and j is the square root of −1. Hence, the phase of the wave arriving at the ith element leads the phase of the wave arriving at the origin by the corresponding ξi.
Next consider the case where all the antennas in the array are separated by the same distance d, leading to a linear array of total length D=(W−1)d. Such an array is sometimes referred to as an equally or uniformly spaced linear array (ULA). Since the excitation is uniform, the array may also be referred to as a uniformly excited ULA. The phase of element i+1 leads the phase of element i by k*d*cos(θ), since the path length to element i+1 is d*cos(θ) meters longer than that to element i. Setting the reference point to element i=0 allows the array factor to be written according to equation 1.
Defining k*d*cos(θ) as φ, the array factor simplifies as shown in equation 2.
AF=Σi=0W−1ejiφ=1+ejφ+ej2φ+ . . . +ej(W−1)φ (2)
As shown in equation 2, the array factor AF is a function of φ and resembles a Fourier Series where the array factor includes a set of sinusoids at multiples of a fundamental frequency φ. Note that because of reciprocity, the array functions similarly in transmit mode except the direction of the phase gradient is reversed to produce a plane wave leaving the array.
Next, consider a two-dimensional planar array having elements (antennas) arranged uniformly in a rectangular grid in an X-Y plane, with element spacing dx along the x-axis and element spacing dy along the y-axis. Since the arrangement is Cartesian (e.g., matrix-like), it is useful to use two indices to refer to the elements: a row index m (e.g., varying along the x-axis) and a column index n (e.g., varying along the y-axis). There may be M total rows and N total columns. The position vector for the mth and nth element is then defined as rmn=x′mn{circumflex over (x)}+y′mnŷ. If the array begins at the origin, the position vector can be rewritten as r′mn=mdx{circumflex over (x)}+ndyŷ. The array factor AF may then be split into two summations along each dimension, written in spherical coordinates as shown in equation 3.
AF(θ,ϕ)=Σn=0N−1ΣEm=0M−1Imnejk(md
In equation 3, Imn denotes the excitation amplitude of the mth and nth element of the array, and is assumed to be a real number yielding broadside radiation. The array factor is said to be separable if the excitations are such that Imn=ImxIyn. That is, the excitation is the product of two functions, one describing variation along the x-axis and another describing variation along the y-axis. A uniform amplitude but progressive phase shifts may be applied in each direction such that Imx=I0exp(jmax) and Iyn=I0exp(jnay), where ax and ay, are the phase gradients in the x and y directions, respectively. This may allow equation 3 to be rewritten as shown in equation 4.
AF(θ,ϕ)=I0Σm=0M−1ejk(md
As shown by equation 4, the array factor may be a product of two linear array factors, one along the vertical dimension (e.g., rows) and the other along the horizontal dimension (e.g., columns). This means that the beamwidths in each of the principal directions of the array may be determined by a linear array along the corresponding direction.
Next consider phased antenna array 88 of
Ideal photodiodes perform a linear conversion from optical power to photocurrent, so the photocurrent at the output of photodiodes 42 may be represented by the equation iph(t)=−1{(ω). {|E(t)|2}}, where (ω) is the frequency dependent responsitivity, E(t) is the complex optical amplitude at the input, and is the Fourier transform function. The complex amplitudes En(t) at the input of each photodiode in a 2N element array can be calculated using equation 5.
In equation 5, 1≤n≤nN, Δω=ω2−ω1, and k(n) denotes the number of ones in the binary representation of (n−1). In this case, the photocurrents iph,n(t) at the outputs of the photodiodes is given by equation 6.
In equation 6, 1≤n≤2N, Δω=ω2−ω1, and DC is the photodiode responsivity at DC. The time delays τN applied in the optical domain yield phase shifts ω1τN in the electrical domain, so optical phase shifters 80 can be used to adjust the electric phases in phased antenna array 88. Specifically, the phase increment Δφn between two adjacent radiators is given by Δφn=ω1·(τn+1τn), where 1≤n≤2N−1.
Whether a photonic beam steering transmitter operates as a true time delay (TTD) or in a phase shift mode is primarily dictated by the location of the delay elements in the photonic network. In the TTD case, the delays TN are applied to the sum of both optical carriers. Modeling the Mach-Zehnder modulator (MZM) (e.g., MZM 58 of
This principle may be used for optoelectronic THz wave beam steering, as shown in the example of
If desired, two or more antennas 30 in phased antenna array 88 may share a corresponding optical phase shifter, thereby allowing for a reduction in the total number of optical phase shifters used to form the signal beam.
As shown in
Phased antenna array 88 may be fed using optical local oscillator signals LO1 and LO2′ (e.g., optical local oscillator signal LO2 that has been modulated with wireless data). Optical splitter 110 (e.g., optical splitter 54B of
Similarly, optical splitter 92 may be coupled to each column 108 of phased antenna array 88 via optical paths 96 (sometimes referred to herein as column lines 96). Optical paths 96 may include optical fibers and/or waveguides. For example, a first optical path 96-1 may couple optical splitter 92 to each of the antennas 30 in column 108-1, a second optical path 96-2 may couple optical splitter 92 to each of the antennas 30 in column 108-2, an Nth optical path 96-N may couple optical splitter 92 to each of the antennas 30 in column 108-N, etc. The example of
As shown in
Each antenna 30 in phased antenna array 88 may include an antenna radiating element such as an antenna radiating element having antenna radiating element arms 36. Each antenna 30 may also include a UTC PD 42 coupled to antenna radiating element arms 36. UTC PD 42 may be illuminated with optical LO signals using optical coupler 90. Optical coupler 90 may include a first arm that is optically coupled to a corresponding optical path 94 for coupling modulated optical signal LO2′ onto UTC PD 42 and may include a second arm that is optically coupled to a corresponding optical path 96 for coupling optical local oscillator signal LO1 onto UTC PD 42. The optical local oscillator signals may control photodiode 42 to produce photocurrent on antenna radiating element arms 36 (e.g., for transmitting THF signals).
If desired, the length of each arm of optical coupler 90 may vary at different antenna positions (e.g., positions (m,n)) across the area of phased antenna array 88 to provide all of the antennas 30 in phased antenna array 88 with a uniform amount of optical power despite being located at different positions along optical paths 94 and 96. For example, antennas 30 located within closer rows 106 and closer columns 108 to optical phase shifters 100 and 98 may include shorter arms in optical coupler 90 than the antennas 30 located in farther rows 106 and farther columns 108, thereby preventing excessive optical power from being coupled out of the optical paths at closer antenna locations prior to reaching farther antenna locations. This may serve to provide each antenna 30 with a uniform amount of optical power in the optical local oscillator signals.
During signal transmission, modulated optical local oscillator signal LO2′ may be provided to each row 106 of antennas 30 over optical paths 94. At the same time, optical local oscillator signal LO1 may be provided to each column 108 of antennas 30 over optical paths 96. Control signals provided to optical phase shifters 100 (e.g., control signals CTRL of
At the same time, control signals provided to optical phase shifters 98 (e.g., control signals CTRL of
In other words, each antenna 30 may share a first optical phase shift with each other antenna 30 in its row (e.g., may share an optical phase shifter 100) and may share a second optical phase shift with each other antenna 30 in its column (e.g., may share an optical phase shifter 98). The optical phase shifts imparted by optical phase shifters 100 (sometimes referred to herein as a first set of optical phase shifts) and the optical phase shifts imparted by optical phase shifters 98 (sometimes referred to herein as a second set of optical shifts) may respectively control the beam pointing direction of the signal beam of THF signals formed by phased antenna array 88 within different orthogonal degrees of freedom. Put differently, the optical phasing of rows 106 and the optical phasing of columns 108 may be programmed to configure phased antenna array 88 to produce a single combined THF signal beam (e.g., using modulated local oscillator signal LO2′ and optical local oscillator signal LO1) oriented in a selected beam pointing direction within the hemisphere over the array. Sharing optical phase shifters 100 and sharing optical phase shifters 98 in this way may allow phased antenna array 88 to perform three-dimensional beam steering using only N+M total optical phase shifters, which is significantly fewer than the N×M total optical phase shifters required when each antenna 30 is independently phased using a respective phase shifter. This may serve to reduce the area and resource consumption of phased antenna array 88 while still allowing the phased antenna array to perform three-dimensional signal beam steering.
Mathematically, the electric field entering the mth row 106 of phased antenna array 88 is represented as Em=amejϕ
A complex data modulation xBB(t) (e.g., carrying wireless data DAT) is added to the optical signals provided to each row 106 (e.g., within modulated optical local oscillator LO2′) but is omitted from the equations described herein for the sake of simplicity. If desired, complex data modulation xBB(t) may be modulated onto the optical local oscillator signal provided to columns 108 rather than to rows 106 (e.g., to optical local oscillator signal LO1 or alternatively, modulated optical local oscillator signal LO2′ may be provided to optical splitter 92 whereas optical local oscillator signal LO1 is provided to optical splitter 110).
For each antenna (pixel) located at position (m,n), the combined optical signal from the corresponding optical path 94-m (row) and the corresponding optical path 96-n (column) is represented by equation 7.
Assuming that frequencies ω2 and ω1 are near-infrared frequencies, where the difference between frequencies φ2 and φ1 gives the frequency of the THF signals conveyed by the corresponding antenna radiating element arms 36 (e.g., 275 GHz or other frequencies), this combined optical signal may cause UTC PD 42 to generate AC photocurrent i, based on the principle of photo-mixing, as expressed by equation 8 for the antenna at position (m,n).
Amplitudes am and bn may be equal with equal power distributing and/or the pixel amplitudes can be generated equally by selecting appropriate lengths for the arms of the optical coupler 90 at each antenna position (m,n). By choosing optical phase shifts ϕm for each row 106 and optical phase shifts θn for each column 108, a corresponding signal beam may be formed in a desired beam steering direction and an overall desired array factor AF can be obtained.
The example of
If desired, a flexible array excitation Imn may be provided in the row and column domain (e.g., not per pixel). If desired, phased antenna array 88 may be configured to concurrently handle multiple THF wavelengths (e.g., for performing carrier aggregation). If desired, the optical local oscillator signal provided to each column may be modulated with wireless data instead of the optical local oscillator signal provided to each row. In the example of
If desired, one or more of the antennas 30 in phased antenna array 88 of
In examples where each polarization is used to convey a respective stream of wireless data (e.g., where antenna 30H conveys data xBB,H and antenna 30V conveys data xBB,V) phased antenna array 88 may include optical paths 94H and 96H for feeding the optical coupler 90H of antenna 30H and may include optical paths 94V and 96V for feeding the optical coupler 90V of antenna 30V (e.g., phased antenna array 88 may include respective optical paths 94 for vertically polarized signals and horizontally polarized signals and may include respective optical paths 96 for vertically polarized signals and horizontally polarized signals). As the data modulation is only served from either a row or column (e.g., column), assuming the same array steering direction for vertical and horizontal polarizations, the row optical paths 94 could serve both polarizations, with the limitation that the input power has to be doubled to serve both polarizations. These examples are merely illustrative. If desired, both polarizations may be used to convey the same stream of wireless data xBB. In these scenarios, the same optical path 96 may feed both optical couplers 90H and 90V and the same optical path 94 may feed both optical couplers 90H and 90V.
If desired, additional material can be provided to antenna(s) 30 to help antenna(s) 30 to focus the transmitted, reflected, and/or reflected THF signals. For example, a THz lens may be provided in device 10 to help antenna(s) 30 to focus the transmitted, received, and/or reflected THF signals.
As shown in
At operation 132, light sources 70 in device 10 (
Optical splitter 110 may output modulated optical local oscillator signal LO2′ on optical paths 94. Optical splitter 92 may output optical local oscillator signal LO1 on optical paths 96. Control circuitry 14 may control the M optical phase shifters 100 on optical paths 94 to impart M respective phase shifts to the modulated optical local oscillator signal LO2′ on optical paths 94 to produce phase-shifted (optical) signals A1, A2, Am, etc. Control circuitry 14 may control the N optical phase shifters 98 on optical paths 96 to impart N respective phase shifts to the modulated optical local oscillator signal LO1 on optical paths 96 to produce phase-shifted (optical) signals B1, B2, BN, etc. Optical paths 94 may feed the phase-shifted signals A to each antenna 30 in the corresponding row 106 of phased antenna array 88 (e.g., the antennas 30 in row 106-1 may be fed using phase-shifted signals A1, the antennas 30 in row 106-2 may be fed using phase-shifted signals A2, etc.) while optical paths 96 concurrently feed the phase-shifted signals B to each antenna 30 in the corresponding column 108 of phased antenna array 88 (e.g., the antennas 30 in column 108-1 may be fed using phase-shifted signals B1, the antennas 30 in column 108-2 may be fed using phase-shifted signals B2, etc.).
The optical coupler 90 in each antenna 30 of phased antenna array 88 may illuminate the corresponding UTC PD 42 with the combination of phase-shifted signal A and phase-shifted signal B provided to that pixel location in the array. For example, the optical coupler 90 in the antenna 30 of row 106-1 and column 108-1 may illuminate the corresponding UTC PD 42 with phase-shifted signal A1 and phase-shifted signal B1, the optical coupler 90 in the antenna 30 of row 106-M and column 108-N may illuminate the corresponding UTC PD 42 with phase-shifted signal AM and phase-shifted signal BN, etc. The antennas 30 may convey THF signals based on the phase-shifted signals used to illuminate the UTC PDs 42 (at operation 134). This may cause each row of antennas 30 to contribute to formation of a THF signal beam that is oriented in a first direction along a first degree of freedom (e.g., within the Y-Z plane) while concurrently causing each column of antennas 30 to contribute to formation of the THF signal beam with orientation in a second direction along a second degree of freedom (e.g., within the X-Z plane). The optical phase shifts provided to the rows 106 and provided to the columns 108 may collectively cause phased antenna array 88 to form a signal beam of THF signals in the selected beam pointing direction (e.g., as identified at operation 130). Processing may subsequently loop back to operation 130 via path 136 to update the beam pointing direction over time (e.g., as device 10 and/or the external communications equipment moves over time). The optical components described herein (e.g., MZM modulator(s), waveguide(s), phase shifter(s), UTC PD(s), etc.) may be implemented in plasmonics technology if desired.
Device 10 may gather and/or use personally identifiable information. It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.
The methods and operations described above in connection with
If desired, in some examples, an electronic device may be provided having: a first light source; a second light source, an array of antennas arranged in rows and columns, each antenna in the array including a respective photodiode coupled to a respective antenna radiating element; first optical paths coupled to the rows of the array; second optical paths coupled to the columns of the array; first optical phase shifters disposed on the first optical paths; and second optical phase shifters disposed on the second optical paths. The first light source may be configured to generate a first optical local oscillator (LO) signal. The second light source may be configured to generate a second optical LO signal. The first optical phase shifters may be configured to output phase-shifted versions of the first optical LO signal on the first optical paths. The second optical phase shifters may be configured to output phase-shifted versions of the second optical LO signal on the second optical paths. The photodiodes may be configured to convey wireless signals using the antenna radiating elements based on the phase-shifted versions of the first optical LO signals and the phase-shifted versions of the second optical LO signals.
If desired, in some examples, an electronic device may be provided having: a first antenna having a first photodiode, a first antenna radiating element coupled to the first photodiode, and a first optical coupler coupled to the first photodiode; a second antenna having a second photodiode, a second antenna radiating element coupled to the second photodiode, and a second optical coupler coupled to the second photodiode; a first optical path coupled to the first optical coupler and the second optical coupler; and a first optical phase shifter. The first optical phase shifter may be configured to generate a first phase-shifted signal on the first optical path by applying a first optical phase shift to a first optical local oscillator (LO) signal. The first photodiode may be configured to transmit first wireless signals using the first antenna radiating element based at least on the first phase-shifted signal. The second photodiode may be configured to transmit second wireless signals using the second antenna radiating element based at least on the first phase-shifted signal.
The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.
This application claims the benefit of U.S. Provisional Patent Application No. 63/247,184, filed Sep. 22, 2021, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | |
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63247184 | Sep 2021 | US |