WO2023003548A1

WO2023003548A1 - Electrical energy harvesting from radio frequency signals

Info

Publication number: WO2023003548A1
Application number: PCT/US2021/042497
Authority: WO
Inventors: Isaac Lagnado; Chih-Hung Chien; Chien-Pai Lai; Cheng-Chih Chen
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2021-07-21
Filing date: 2021-07-21
Publication date: 2023-01-26

Abstract

In one example in accordance with the present disclosure, an electronic device is described. An example electronic device includes an antenna, communication circuitry to receive radio frequency (RF) signals on the antenna, and RF harvest circuitry to generate electrical energy from the RF signals received on the antenna. The example electronic device also includes a switch to couple the antenna to one of the communication circuitry and the RF harvest circuitry in a first state. The switch is to couple the antenna to the other of the communication circuitry and the RF harvest circuitry in a second state.

Description

ELECTRICAL ENERGY HARVESTING FROM RADIO FREQUENCY SIGNALS

BACKGROUND

[0001] Electronic devices include wireless antennas to transmit information between electronic devices that are not physically connected to one another. Antennas wirelessly communicate with other antennas using radio frequency (RF) signals. In some cases, antennas are used to communicate over a wireless network. Different wireless networks include different communication protocols and the antennas that are a part of a wireless network communicate in compliance with those protocols.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The accompanying drawings illustrate various examples of the principles described herein and are part of the specification. The illustrated examples are given merely for illustration, and do not limit the scope of the claims.

[0003] Fig. 1 is a block diagram of an electronic device to harvest electrical energy from RF signals, according to an example.

[0004] Fig. 2 is a block diagram of another electronic device to harvest electrical energy from RF signals, according to an example.

[0005] Fig. 3 illustrates an electronic device with multiple antennas, according to an example. [0006] Fig. 4 is a block diagram illustrating an electronic device with multiple antennas that may be switchably coupled to communication circuitry or RF harvest circuitry, according to an example.

[0007] Fig. 5 is a block diagram illustrating an electronic device with a controller to adjust a switch coupling an antenna to communication circuitry or RF harvest circuitry, according to an example.

[0008] Fig. 6 is a block diagram of an electronic device with an antenna frequency tuner, according to an example.

[0009] Fig. 7 is a block diagram of an electronic device with an antenna pattern tuner, according to an example.

[0010] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

DETAILED DESCRIPTION

[0011] In some examples, electronic devices may include a number of antennas to facilitate wireless communication. For example, an electronic device may include a wireless local area network (WLAN) (e.g., Wi-Fi) antenna that allows the electronic device to transmit and receive information via a WLAN. As another example, the electronic device may include a wireless wide area network (WWAN) (e.g., LTE) antenna that allows the electronic device to transmit and receive information via a WWAN. Each of these different networks incorporate different communication protocols. As the different wireless networks have different operating parameters and communication protocols, each may be particularly tailored to a particular environment.

[0012] In some examples, an electronic device may include an antenna or multiple antennas for two-way communication (e.g., transmission and reception). In some examples, an electronic device may include an antenna or multiple antennas for one-way communication (e.g., reception).

[0013] While wireless communication has undoubtedly shaped the way in which society communicates with one another, some characteristics impact their more thorough implementation. For example, an electronic device that communicates on a wireless network may be powered by a battery. When disconnected from a power source, the battery may provide a fixed amount of power before the battery is recharged.

[0014] In some examples, battery life is a performance characteristic that a user can easily observe. For example, battery life impacts how a user uses an electronic device. As the battery reaches a low level, a user may reduce using the electronic device, or may lose access to the electronic device if the battery is depleted.

[0015] In wireless communication, radio frequency (RF) signals may be transmitted and received on antennas. For example, a transmitter may convert information into RF signals that are sent using an antenna. A receiver may convert information included in RF signals received on an antenna into a usable form.

[0016] RF signals include an amount of energy. RF energy (also referred to as radiation) is a form of electromagnetic energy that includes waves of electric and magnetic energy moving together (e.g., radiating) through space. Energy waves may be classified based amplitude (the height of the wave) and frequency (the distance between the waves or their wavelength). An RF field has both an electric and a magnetic component (electric field and magnetic field).

[0017] In some examples, an electronic device may include RF harvest circuitry to convert energy from RF signals into electrical energy. RF harvest circuitry may capture and convert electromagnetic energy (e.g., RF signals) into a usable direct current (DC) voltage. For example, RF harvest circuitry may include an impedance matching network and a rectifier circuit that converts the alternating current (AC) of the RF signal into DC energy, which may be stored in a battery or directly used by the electronic device. In some examples, a voltage multiplier may be used in the rectifier circuit. For example, a voltage multiplier is a type of rectifier circuit that converts and boosts AC input to DC output. In some cases where rectified power is inadequate for an application, the output DC may be boosted by stacking single rectifiers into series, forming a voltage multiplier.

[0018] In some examples, the present specification describes electronic devices that may dynamically switch an antenna from communication circuitry to RF harvest circuitry. As used herein, communication circuitry may include electronic components that are used to perform radio communication operations. For example, communication circuitry may include a transmitter, a receiver, or a transceiver (i.e. , both a transmitter and a receiver). A transmitter may produce an RF alternating current, which is applied to an antenna and radiated as an RF signal. A receiver may include circuitry that receives RF signals from the antenna and converts the RF signals into usable information.

As used herein, radio communication operations may include transmitting RF signals, receiving RF signals, ora combination thereof.

[0019] An electronic device may include an antenna to perform radio communication operations. In the examples described herein, RF harvest circuitry may be used to generate electrical energy from the RF signals received on the antenna. For example, a switch may be used to couple either the communication circuitry or the RF harvest circuitry to the antenna. In some examples, a second antenna of the electronic device may be the source of the RF signals used by the RF harvest circuitry to generate electrical energy.

[0020] Specifically, the present specification implements an electronic device with an antenna, communication circuitry to receive RF signals on the antenna, and RF harvest circuitry to generate electrical energy from the RF signals received on the same antenna. The example electronic device also includes a switch to couple the antenna to one of the communication circuitry and the RF harvest circuitry in a first state, and to couple the antenna to the other of the communication circuitry and the RF harvest circuitry in a second state.

[0021] In another example, the present specification also describes an electronic device that includes a first antenna and a second antenna. The example electronic device also includes communication circuitry to transmit first RF signals on the first antenna, and RF harvest circuitry to generate electrical energy from second RF signals received on the first antenna. The example electronic device further includes a switch to selectively couple the first antenna to one of the communication circuitry and the RF harvest circuitry based on communication circuitry activity and second antenna activity.

[0022] In yet another example, the present specification also describes an electronic device that includes an antenna, communication circuitry to transmit first RF signals on the antenna, and RF harvest circuitry to generate electrical energy from second RF signals received on the antenna. The example electronic device also includes a switch to selectively couple the antenna to one of the communication circuitry and the RF harvest circuitry. The example electronic device further includes a controller to monitor a communication circuitry state, and to adjust the switch to couple the antenna to one of the communication circuitry and the RF harvest circuitry based on the communication circuitry state.

[0023] As used in the present specification and in the appended claims, the term, “controller” may be a processor, an application-specific integrated circuit (ASIC), a semiconductor-based microprocessor, a central processing unit (CPU), and a field-programmable gate array (FPGA), and/or other hardware device.

[0024] The memory may include a computer-readable storage medium, which computer-readable storage medium may contain, or store computer- usable program code for use by or in connection with an instruction execution system, apparatus, or device. The memory may take many types of memory including volatile and non-volatile memory. For example, the memory may include Random Access Memory (RAM), Read Only Memory (ROM), optical memory disks, and magnetic disks, among others. The executable code may, when executed by the respective component, cause the component to implement the functionality described herein.

[0025] Turning now to the figures, Fig. 1 is a block diagram of an electronic device 100 to harvest electrical energy from RF signals, according to an example. Examples of an electronic device 100 include a tablet computer, laptop computer, desktop computer, internet-of-things device (e.g., sensor), gaming console, gaming controller, robot, or other device that includes an antenna 102 for RF communications. In some examples, the antenna 102 may send and receive RF signals.

[0026] The electronic device 100 may include communication circuitry 104 to receive or transmit RF signals on the antenna 102. In this example, the communication circuitry 104 may include a receiver to receive the RF signals. In some examples, the communication circuitry 104 may include a transmitter or a transceiver that may utilize the same antenna 102.

[0027] In some examples, the electronic device 100 includes RF harvest circuitry 106 to generate electrical energy from the RF signals received on the antenna 102. As described above, the RF harvest circuitry 106 may include an impedance matching network and a rectifier circuit that converts the alternating current (AC) of the RF signal into DC energy. This electrical energy may be used by the electronic device 100 to power circuitry or charge a battery.

[0028] The electronic device 100 includes a switch 108 to couple the antenna 102 to one of the communication circuitry 104 and the RF harvest circuitry 106 in a first state. The switch 108 may couple the antenna 102 to the other of the communication circuitry 104 and the RF harvest circuitry 106 in a second state. In other words, the switch 108 may connect either the communication circuitry 104 or the RF harvest circuitry 106 to the antenna 102 at any given time. In some examples, for the RF harvesting functionality to operate in a dead battery scenario, a default state of the switch 108 may be to couple the antenna 102 to the RF harvest circuitry 106. This may allow the RF harvesting to continue even if battery is dead and allows for charging of battery. [0029] In some examples, the switch 108 may be implemented as a single pole double throw (SPDT) switch. The antenna 102 may be connected to a terminal of the switch 108 that can connect to either the communication circuitry 104 or the RF harvest circuitry 106. Thus, the switch 108 may have a state in which the antenna 102 is connected to the communication circuitry 104 and the RF harvest circuitry 106 is disconnected from the antenna 102. In another state, the antenna 102 is connected to the RF harvest circuitry 106 and the communication circuitry 104 is disconnected from the antenna 102.

[0030] In some examples, the switch 108 is to couple the antenna 102 to the communication circuitry 104 when the communication circuitry 104 is active. In one example, the communication circuitry 104 may be active when the communication circuitry 104 powered on. In another example, the communication circuitry 104 may be active when the communication circuitry 104 is to receive RF signals. For example, the communication circuitry 104 may be scheduled to receive an RF signal transmission. During the time that the communication circuitry 104 is to receive the RF signal transmission, the switch 108 may couple the antenna 102 to the communication circuitry 104.

[0031] In another example, the communication circuitry 104 may be active during a transmission by the communication circuitry 104. For example, when the communication circuitry 104 is to transmit RF signals, the switch 108 may couple the antenna 102 to the communication circuitry 104.

[0032] In some examples, the switch is to couple the antenna 102 to the RF harvest circuitry 106 when the communication circuitry 104 is inactive. In some examples, the communication circuitry 104 may be inactive when the communication circuitry 104 is in an OFF state. The switch 108 may couple the antenna 102 to the RF harvest circuitry 106 when the communication circuitry 104 is in the OFF state. In some examples, the communication circuitry 104 may be inactive when the communication circuitry 104 is in an idle state.

[0033] In some examples, the communication circuitry 104 may include a control pin. For example, the control pin may set the communication circuitry 104 in an OFF state (e.g., power OFF state) or an ON state (power ON state). The switch 108 may couple the antenna 102 to the RF harvest circuitry 106 when the control pin for the communication circuitry 104 is in the OFF state. For example, a control signal for the switch 108 may be coupled to the control pin of the communication circuitry 104. When the control pin of the communication circuitry 104 is OFF, the switch 108 may couple the RF harvest circuitry 106 to the antenna 102 such that the RF harvest circuitry 106 can receive RF signals and generate electrical energy. When the control pin of the communication circuitry 104 is ON, the switch 108 may couple the antenna 102 to the communication circuitry 104 such that the communication circuitry 104 can send or receive RF signals.

[0034] In some examples, firmware of the communication circuitry 104 may assign a general-purpose input/output (GPIO) pin on the switch 108 to trigger a change in the switch states. For example, when the communication circuitry firmware determines that the communication circuitry 104 is not actively using the antenna 102, the communication circuitry firmware may send a signal on the GPIO pin to cause the switch 108 to couple the antenna 102 to the RF harvest circuitry 106.

[0035] In some examples, the switch 108 is to couple the antenna 102 to the RF harvest circuitry 106 when RF signals received at the antenna 102 are within a frequency band. In this case, the antenna switching may occur automatically based on the frequency of received RF signals. For example, if received RF signals have a frequency band used by the communication circuitry 104, then the switch 108 may couple the antenna 102 to the communication circuitry 104. However, if the received RF signals have a frequency band outside the frequencies used by the communication circuitry 104, then the switch 108 may automatically couple the antenna 102 to the RF harvest circuitry 106. In this example, the electronic device 100 may include circuitry to detect the frequency of the RF signals received on the antenna 102 and to cause the switch to change states based on the detected frequency.

[0036] In some examples, the frequency band may be detected by the communication circuitry 104. For example, the switch 108 may couple the antenna 102 to the communication circuitry 104. The communication circuitry 104 may determine that the frequency band of a received RF signal is outside the frequency band used by the communication circuitry 104. For example, the communication circuitry 104 may use a given frequency band for communication with a base station or access point during WWAN operation. If the communication circuitry 104 detects that the received RF signal is outside the frequency band used by the communication circuitry 104, then the switch 108 may couple the antenna 102 to the RF harvest circuitry 106. [0037] In some examples, the switching between communication and RF harvesting can be done more passively utilizing resonant circuits. This approach may be used if the expected communication and RF harvesting frequencies have significant separation. Using a passive resonant circuit, when frequencies meant for communication are encountered, a capacitor and inductive component may passively drive the energy to the communication circuitry 104. On the other hand, if energy received on the antenna 102 closely matches the RF harvesting frequencies, then the resonant circuit will have capacitance and inductive component selections which will forward energy to the RF harvesting circuitry 106 instead.

[0038] As seen by these examples, the electronic device 100 may perform electrical energy harvesting without using an extra antenna. Rather, the antenna 102 used by the communication circuitry 104 may be coupled to the RF harvest circuitry 106. This may reduce the costs and size of the electronic device 100. [0039] Fig. 2 is a block diagram of another electronic device 200 to harvest electrical energy from RF signals, according to an example. In this example, the electronic device 200 may be implemented according to the electronic device 100 of Fig. 1. However, in this example, the electronic device 200 includes multiple antennas. For example, the electronic device 200 may include a first antenna 202 and a second antenna 210.

[0040] In some examples, the first antenna 202 may be used for a first radio technology and the second antenna 210 may be used for a second radio technology. For example, the first antenna 202 may be used for communicating on a WWAN according to a communication protocol (e.g., 2G, 3G, 4G, 5G, LTE, New Radio (NR), etc.). The second antenna 210 may be used for communication on a WLAN according to a second communication protocol (e.g., IEEE 802.11). In this case, first antenna 202 may be referred to as a WWAN antenna and the second antenna 210 may be referred to as a WLAN antenna. The electronic device 200 may include communication circuitry 204 to transmit first RF signals on the first antenna 202. The electronic device 200 may include second communication circuitry (not shown) to transmit or receive RF signals on the second antenna 210. Fig. 3 illustrates an example of an electronic device with multiple antennas.

[0041] Referring briefly to Fig. 3, the electronic device 300 includes four antennas 302-1 , 302-2, 302-3, 302-4 for a first radio technology and two antennas 310-1, 310-2 fora second radio technology (represented with dashed lines in Fig. 3). In an example, the first radio technology antennas 302-1 , 302-2,

302-3, 302-4 may be WWAN antennas and the second radio technology antennas 310-1, 310-2 may be WLAN antennas. In some examples, the electronic device 300 may be a laptop computer or a tablet computer. It should be noted that other types of devices are encompassed in the example of Fig. 3. [0042] In some examples, antennas of an electronic device 300 may be close to each other. This may result in low antenna-to-antenna isolation such that the RF energy emitted by one antenna may be received by another antenna. Therefore, an antenna or multiple antennas of the electronic device 300 may be used as a source for RF signals for harvesting electrical energy by RF harvest circuitry. For example, antenna 310-1 may transmit a first RF signal

303-1 and antenna 310-2 may transmit a second RF signal 303-2.

[0043] In this example, antenna 302-1 may be located a distance D1 301-1 from antenna 310-1 while antenna 302-3 may be located a greater distance D3 301-3 from antenna 310-1. Also in this example, antenna 302-2 may be located a distance D2301-2 from antenna 310-2 while antenna 30243 may be located a greater distance D4301-4 from antenna 310-2.

[0044] In some examples, switching for RF harvesting may be based on the proximity of the antennas to an RF source antenna. For example, the closer an antenna is to an RF source antenna, the stronger the RF coupling may be. Stronger RF coupling may result in greater RF harvesting than weaker RF coupling.

[0045] In this example, antenna 310-1 is located closer to antenna 310-1 than antenna 302-3. Also in this example, antenna 310-2 is located closer to antenna 310-2 than antenna 302-4. Because of the proximity of antenna 302-1 to antenna 310-1 (as compared to distance D3301-3 of antenna 302-3), transmission packets of RF signals 303-1 from antenna 310-1 may exhibit stronger coupling with antenna 302-1 than antenna 302-3. Similarly, transmission packets of RF signals 303-2 from antenna 310-2 may exhibit stronger coupling with antenna 302-2 than antenna 302-4. In some examples, switches may be added to antenna 302-1 and antenna 302-2 to guide the coupled RF signals to the RF harvest circuitry.

[0046] Referring again to Fig. 2, the second antenna 210 may be used as a source of RF energy to drive the RF harvest circuitry 206. Second RF signals may be transmitted by the second antenna 210 and received by the first antenna 202. The RF harvest circuitry 206 may generate electrical energy from the second RF signals received on the first antenna 202.

[0047] The electronic device 200 may include a switch 208 to selectively couple the first antenna 202 to one of the communication circuitry 204 and the RF harvest circuitry 206 based on communication circuitry activity and second antenna activity. For example, the switch 208 may couple the first antenna 202 to the RF harvest circuitry 206 when the communication circuitry 204 is inactive and the second antenna 210 is transmitting the second RF signals. When the communication circuitry 204 is active (e.g., actively transmitting or receiving first RF signals), the switch 208 may couple the first antenna 202 to the communication circuitry 204.

[0048] In some examples, the switch 208 may be controlled to couple the first antenna 202 to the RF harvest circuitry 206 based on activity of the second antenna 210. For example, the electronic device 200 may include a controller that monitors the state of the second antenna 210. When the second antenna 210 is transmitting, the switch 208 may be set to couple the first antenna 202 to the RF harvest circuitry 206. In some examples, the controller may also ensure that the communication circuitry 204 is inactive (e.g., powered off, idle, not scheduled to transmit/receive) when the switch 208 is set to couple the first antenna 202 to the RF harvest circuitry 206. Examples where a controller is used to monitor the communication circuitry 204, the RF harvest circuitry 206 and second antenna activity to adjust the switch 208 are described in Fig. 5. [0049] As seen in the example of Fig. 2, the use of a separate antenna to couple the RF signals to the RF harvest circuitry 206 is avoided. Instead, existing antennas 202, 210 may be used for RF harvesting. This also avoids impacting antenna performance on the communication circuitry. By leveraging a single antenna to do both RF communication and RF harvesting, the use of an additional antenna is avoided. With fewer antennas in the system, it is likely that each of the remaining antennas will have additional volume, which may translate to better performance. These examples may be used in electronic devices where antennas are crowded inside a small form factor, and where the antennas or communication circuitry are not all turned ON at once. Thus, energy may be harvested while some radios are idled. This could enable using more applications on the electronic device or extend the usage time. Also, as seen in these examples, by avoiding adding extra antennas into the electronic device 200, impacts to the dimensions of the electronic device 200 are minimized. [0050] Fig. 4 is a block diagram illustrating an electronic device 400 with multiple antennas 402-1 , 402-2 that may be switchably coupled to communication circuitry 404 or RF harvest circuitry 406, according to an example. In this example, a first switch 408-1 may be coupled to a first antenna 402-1. A second switch 408-2 may be coupled to a second antenna 402-2. The first switch 408-1 may connect the first antenna 402-1 to one of the communication circuitry 404 ora RF power combiner 416. The second switch 408-2 may connect the second antenna 402-2 to one of the communication circuitry 404 or the RF power combiner 416.

[0051] In some examples, the communication circuitry 404 may use the first antenna 402-1 and the second antenna 402-2 for radio communications. For example, when the communication circuitry 404 is active, the communication circuitry 404 may transmit or receive RF signals on the first antenna 402-1 , the second antenna 402-2, ora combination thereof.

[0052] In some examples, when the communication circuitry 404 is inactive (e.g., powered off, idle, not scheduled to transmit/receive), then the switches 408-1 , 408-2 may be set to couple the antennas 402-1, 402-2 to the RF power combiner 416. In some examples, the RF power combiner 416 may combine the power from the RF signals received on the antennas 402-1, 402-2. For example, the RF power combiner 416 may be implemented as an RF T-junction in which multiple power sources are aggregated into a single output power port. The RF power combiner 416 may provide an RF signal to the RF harvest circuitry 406 to generate electrical energy. In some examples, the RF power combiner 416 may have directional characteristics that allow energy toward the RF harvest circuitry 406, but restrict energy from running back into the secondary path. For example, energy from the first antenna 402-1 may travel to RF harvest circuitry 406 without being directed to the second antenna 402-2, and vice versa.

[0053] In some examples, the switches 408-1 , 408-2 may be independently controlled. For example, the first switch 408-1 may couple the first antenna 402- 1 to the communication circuitry 404 while the second switch 408-2 couples the second antenna 402-2 to the RF harvest circuitry 406, and vice versa.

[0054] In some examples, the state of the switches 408-1 , 408-2 may be determined based on multiple-input multiple-output (MIMO) operation of the communication circuitry 404. With MIMO, multiple antennas may be used for radio communication. In some modes of MIMO, a subset of antennas may be used for radio communication. For example, in 4x4 MIMO, an electronic device 400 may use four antennas for four simultaneous data streams, while 2x2 MIMO may use two antennas for two simultaneous data streams.

[0055] In the example of Fig. 4, both antennas 402-1 , 402-2 may be used for 2x2 MIMO. In this case, the switches 408-1, 408-2 may couple both antennas 402-1 , 402-2 to the communication circuitry 404. However, for non-MIMO operation, one of the antennas (e.g., the first antenna 402-1) may be coupled to the communication circuitry 404 and the other antenna (e.g., the first antenna 402-2) may be coupled to the RF power combiner 416. In some examples, the determination of which antenna to couple to the RF power combiner 416 may be based on the location of the antennas with regard to an RF signal source. For example, if the second antenna 402-2 is located closer than the first antenna 402-1 to a transmitting antenna for a second radio technology, then the second antenna 402-2 may be coupled to the RF power combiner 416 for non-MIMO operation or when operating in a reduced MIMO mode (e.g., 2x2 MIMO instead of 4x4 MIMO). It should be noted that by operating in a reduced MIMO mode, the connection with a base station or other remote device may be maintained with a reduced downlink throughput.

[0056] In some examples, the communication circuitry 404 may use a GPIO pin connected to the switches 408-1, 408-2. The communication circuitry 404 may trigger the switches 408-1 , 408-2 to couple to the communication circuitry 404 when the communication circuitry 404 is scheduled to transmit or receive on the antennas 402-1 , 402-2.

[0057] It should be noted that while two antennas 402-1 , 402-2 are depicted in the example of Fig.4, the principles of Fig. 4 may be extended to any number of antennas. For example, if the electronic device 400 includes four antennas for a given radio technology, then the four antennas may be coupled to four switches that selectively couple the antennas to the communication circuitry 404 or the RF power combiner 416.

[0058] Fig. 5 is a block diagram illustrating an electronic device 500 with a controller 512 to adjust a switch coupling an antenna 502 to communication circuitry 504 or RF harvest circuitry 506, according to an example. In this example, the electronic device 500 may be implemented according to the electronic device 100 of Fig. 1.

[0059] The electronic device 500 may also include a controller 512 to monitor a communication circuitry state. Some examples of the controller 512 include a processor, microcontroller unit (MCU), embedded controller, Basic Input/Output System (BIOS), and platform controller hub (PCH).

[0060] As used herein, a BIOS refers to hardware or hardware and instructions to initialize, control, or operate a computing device prior to execution of an operating system (OS) of the computing device. Instructions included within a BIOS may be software, firmware, microcode, or other programming that defines or controls functionality or operation of a BIOS. In one example, a BIOS may be implemented using instructions, such as platform firmware of a computing device, executable by a processor. A BIOS may operate or execute prior to the execution of the OS of a computing device. A BIOS may initialize, control, or operate components such as hardware components of a computing device and may load or boot the OS of computing device. [0061] In some examples, a BIOS may provide or establish an interface between hardware devices or platform firmware of the computing device and an OS of the computing device, via which the OS of the computing device may control or operate hardware devices or platform firmware of the computing device. In some examples, a BIOS may implement the Unified Extensible Firmware Interface (UEFI) specification or another specification or standard for initializing, controlling, or operating a computing device.

[0062] In some examples, the controller 512 may monitor the drivers of the communication circuitry 504 to determine whether the communication circuitry 504 is active (e.g., transmitting or receiving) or inactive (e.g., powered off, idle, not scheduled to transmit/receive). The controller 512 may adjust the switch 508 to couple the antenna 502 to one of the communication circuitry 504 and the RF harvest circuitry 506 based on the communication circuitry state. For example, if the controller 512 determines that the communication circuitry is in an idle state (or other inactive state), the controller 512 may adjust the switch 508 to couple the antenna 502 to the RF harvest circuitry 506 in response to determining that the communication circuitry is in the idle state (or other inactive state). However, in this example, if the communication circuitry 504 is active, then the controller 512 may adjust the switch 508 to couple the antenna 502 to the communication circuitry 504.

[0063] In some examples, the controller 512 may determine that the communication circuitry 504 is in an active mode (e.g., powered on), but the communication circuitry 504 may not be scheduled to receive or transmit RF signals. In this case, the controller 512 may generate a control signal 514 to adjust the switch 508 to couple the antenna 502 to the RF harvest circuitry 506 during times that the communication circuitry 504 is not actively transmitting or receiving. In some examples, the control signal 514 may be implemented as a general-purpose input/output (GPIO) pin coupled between the switch 508 and the controller 512. In this case, a first voltage state of the control signal 514 may cause the switch 508 to connect to the communication circuitry 504 and a second voltage state of the control signal 514 may cause the switch 508 to connect to the RF harvest circuitry 506. [0064] In some examples, the controller 512 may monitor the communication circuitry 504 to determine a MIMO state of the antenna 502. The controller 512 may then adjust the switch 508 to couple the antenna 502 to the RF harvest circuitry 506 based on the MIMO state of the antenna 502. For example, if the communication circuitry 504 uses multiple antennas to communicate using MIMO, then the antenna 502 may be in an active MIMO state or an inactive MIMO state. For example, if the electronic device 500 has four antennas and the communication circuitry 504 is performing 4x4 MIMO, then the antenna 502 may be in an active MIMO state. In this case, the controller 512 may send a control signal 514 to the switch 508 to couple the antenna 502 with the communication circuitry 504. However, not all networks support 4x4 MIMO. Therefore, if the electronic device 500 includes four antennas and the communication circuitry 504 is performing 2x2 MIMO, then the antenna 502 may not be used for the 2x2 MIMO. In this case, the controller 512 may send a control signal 514 to the switch 508 to couple the antenna 502 with the communication circuitry 504.

[0065] In some examples, the controller 512 may determine an RF harvest priority based on a number of factors. The RF harvest priority may indicate whether energy harvesting by the RF harvest circuitry 506 has a higher or lower priority than communication operations by the communication circuitry 504. In some examples, the controller 512 may monitor the RF harvest circuitry 506 to determine an RF harvest circuitry state. In some examples, RF harvest circuitry status update may be from the operating system (OS) layer through a driver/application or through a low layer protocol (e.g., Inter-Integrated Circuit (I2C), Serial Peripheral Interface (SPI)). Some examples of RF harvest circuitry states that the RF harvest circuitry 506 may inform the controller 512 include battery level (e.g., battery voltage), charge rate, and discharge rate.

[0066] In an example, if the controller 512 determines that the battery (e.g., a coin battery) of the electronic device 500 is less than a threshold amount (e.g., less than a voltage threshold), then the controller 512 may raise the RF harvest priority to cause the switch 508 to connect to the RF harvest circuitry 506 even if the communication circuitry 504 is active. In this case, the controller 512 may instruct the communication circuitry 504 to limit activity to allow the RF harvest circuitry 506 time to charge the battery. In some examples, the controller 512 may instruct the communication circuitry 504 to limit activity by switching from a high MIMO state (e.g., 4x4 MIMO) to a lower MIMO state (e.g., 2x2 MIMO). In some examples, the controller 512 may instruct the communication circuitry 504 to limit activity by reducing the duty cycle of communication operations by the communication circuitry 504. In some examples, the controller 512 may instruct the communication circuitry 504 to limit or restore activity through driver communication or through advanced configuration and power interface (ACPI) communication.

[0067] In some examples, the controller 512 may monitor activity of an RF signal source. For example, if the electronic device 500 includes second communication circuitry fora second radio technology, the controller 512 may monitor when the second communication circuitry transmits. In this case, the RF signals transmitted by the second communication circuitry may be a source of RF energy for the RF harvest circuitry 506. In another example, the electronic device 500 may be in close proximity to a remote transmitter (e.g., a base station, access point, etc.) that sends RF signals. If the controller 512 detects that activity (e.g., transmission duty cycles) of the RF signal source is greater than a threshold, then the controller 512 may determine that the RF signal source is in a state of heavy transmission. In this case, the controller 512 may raise the RF harvest priority to switch to the RF harvest circuitry 506 as there is RF energy available to harvest.

[0068] In some examples, the controller 512 may determine the RF harvest priority based on the RF signal source activity and the communication circuitry state. For example, if the RF signal source activity is greater than a threshold and the communication circuitry is in an inactive state, then the controller 512 may set the RF harvest priority to cause the switch 508 to connect to the RF harvest circuitry 506. If the RF signal source activity is less than a threshold or if the communication circuitry is in an active state, then the controller 512 may set the RF harvest priority to cause the switch 508 to connect to the communication circuitry 504. The controller 512 may then adjust the switch 508 to couple the antenna 502 to the RF harvest circuitry 506 based on the RF harvest priority. For example, if the RF harvest priority is greater than a threshold amount, then the controller 512 may send a control signal 514 to cause the switch 508 to couple the antenna 502 to the RF harvest circuitry 506.

[0069] In some examples, the controller 512 may determine the RF harvest priority based on scores for different criteria. In an example, the RF harvest priority scoring may be accomplished as depicted in Table 1.

Table 1

[0070] In Table 1 , the RF Signal Source Activity scoring factor may be determined based on transmission duty cycles of an RF signal source. The controller 512 may compare the RF signal source activity to a transmission threshold. If the RF Signal Source Activity is greater than a threshold, then the controller 512 may add 1 to the RF harvest priority score, otherwise, the controller 512 may subtract 1 from the RF harvest priority score.

[0071] In Table 1, the controller 512 may determine the score for the RF harvest circuitry status based on a battery level. If the battery level is less than a threshold amount (e.g., a threshold voltage amount), then the controller 512 may add 1 to the RF harvest priority score, otherwise, the controller 512 may subtract 1 from the RF harvest priority score.

[0072] In Table 1, the controller 512 may also determine the score for the communication circuitry status based on the state of the communication circuitry 504. For example, if the communication circuitry 504 is inactive (e.g., powered off, idle, not scheduled to transmit/receive), then the communication circuitry status may be less than an activity threshold. If the communication circuitry status is less than the activity threshold, then the controller 512 may add 1 to the RF harvest priority score, otherwise, the controller 512 may subtract 1 from the RF harvest priority score. Furthermore, if the communication circuitry 504 is actively communicating on the antenna 502, but the duty cycle for transmission or reception is less than a threshold amount, then the controller 512 may add 1 to the RF harvest priority score, otherwise, the controller 512 may subtract 1 from the RF harvest priority score.

[0073] The controller 512 may determine whether the RF harvest priority score is greater than a threshold score. For example, if the combined RF harvest priority score is greater than or equal to zero, then the controller 512 may send a control signal 514 to cause the switch 508 to couple the antenna 502 to the RF harvest circuitry 506. If the combined RF harvest priority score is less than zero, then the controller 512 may send a control signal 514 to cause the switch 508 to couple the antenna 502 to the communication circuitry 504. It should be noted that the threshold score may be adjusted to favor coupling to the RF harvest circuitry 506 or the communication circuitry 504.

[0074] As seen by this example, dynamically scoring the RF harvest priority may control the RF signal path in an intelligent way. It should be noted that in this example, three scoring factors were used to determine the RF harvest priority. However, other parameters may be monitored by the controller 512 and used as scoring factors to determine the RF harvest priority.

[0075] Fig. 6 is a block diagram of an electronic device 600 with an antenna frequency tuner 620, according to an example. The electronic device 600 may be implemented according to the examples described herein. For example, the electronic device 600 may include an antenna 602, communication circuitry 604, RF harvest circuitry 606, a switch 608, and a controller 612 that are implemented as described herein.

[0076] In some examples, to enhance energy harvesting by the RF harvest circuitry 606, the electronic device 600 may include an antenna frequency tuner 620 coupled to the antenna 602. The antenna frequency tuner 620 may include circuitry to adjust the frequency band of the antenna 602. For example, the antenna frequency tuner 620 may adjust the frequency band of the antenna 602 to match the frequency band of an RF signal source. The antenna frequency tuner 620 may increase the efficiency of the RF harvest circuitry 606 by providing stronger RF signal coupling between antennas.

[0077] If the electronic device 600 includes multiple antennas, a first antenna (e.g., antenna 602) may be coupled to the RF harvest circuitry 606 and the communication circuitry 604 via the switch 608. A second antenna may transmit RF signals that are received on the first antenna. In this case, the antenna frequency tuner 620 may adjust the first antenna frequency band based on the second antenna frequency band in response to the switch 608 coupling the first antenna to the RF harvest circuitry 606.

[0078] In some examples, the controller 612 may send a control signal 614-2 to the antenna frequency tuner 620 to adjust the frequency band of the antenna 602. For example, when the controller 612 determines that the switch 608 is to couple the antenna 602 to the RF harvest circuitry 606, then the controller 612 may send a control signal 614-1 to cause the switch 608 to couple the RF harvest circuitry 606. The controller 612 may also send a control signal 614-2 to the antenna frequency tuner 620 to adjust the frequency band of the antenna 602 based on the frequency of the RF signal source. When the controller 612 determines that the switch 608 is to couple the antenna 602 to the communication circuitry 604, then the controller 612 may send a control signal 614-1 to cause the switch 608 to couple the communication circuitry 604. The controller 612 may also send a control signal 614-2 to the antenna frequency tuner 620 to adjust the frequency band of the antenna 602 based on the frequency of the communication circuitry 604.

[0079] Fig. 7 is a block diagram of an electronic device 700 with an antenna pattern tuner 722, according to an example. The electronic device 700 may be implemented according to the examples described herein. For example, the electronic device 700 may include an antenna 702, communication circuitry 704, RF harvest circuitry 706, a switch 708, and a controller 712 that are implemented as described herein.

[0080] As with the example of Fig. 6, in some examples, to enhance energy harvesting by the RF harvest circuitry 706, the electronic device 700 may include an antenna pattern tuner 722 coupled to the antenna 702. The antenna pattern tuner 722 may include circuitry to adjust the radiation pattern of the antenna 702. In some examples, the antenna pattern tuner 722 may include additional layout (e.g., metallic traces) to facilitate adjustments to the antenna radiation pattern. For example, the antenna pattern tuner 722 may adjust the radiation pattern of the antenna 702 based on the direction of an RF signal source. The antenna pattern tuner 722 may increase the efficiency of the RF harvest circuitry 706 by providing stronger RF signal coupling between antennas.

[0081] If the electronic device 700 includes multiple antennas, a first antenna (e.g., antenna 702) may be coupled to the RF harvest circuitry 706 and the communication circuitry 704 via the switch 708. A second antenna may transmit RF signals that are received on the first antenna. In this case, the antenna pattern tuner 722 may adjust the antenna radiation pattern toward the RF signal source (e.g., second antenna, base station, access point, etc.) in response to the switch 708 coupling the first antenna to the RF harvest circuitry 706. It should be noted that in some examples, the RF signal source may be a self- originated RF signal such as from a second antenna or the electronic device 700. In some examples, the antenna pattern tuner 722 may be used to direct the antenna radiation pattern to outside sources (e.g., base station, access point, etc.) as well.

[0082] In some examples, the controller 712 may send a control signal 714-2 to the antenna pattern tuner 722 to adjust the radiation pattern of the antenna 702. For example, when the controller 712 determines that the switch 708 is to couple the antenna 702 to the RF harvest circuitry 706, then the controller 712 may send a control signal 714-1 to cause the switch 708 to couple the RF harvest circuitry 706. The controller 712 may also send a control signal 714-2 to the antenna pattern tuner 722 to adjust the radiation pattern of the antenna 702 based on the direction of the RF signal source. When the controller 712 determines that the switch 708 is to couple the antenna 702 to the communication circuitry 704, then the controller 712 may send a control signal 714-1 to cause the switch 708 to couple the communication circuitry 704. The controller 712 may also send a control signal 714-2 to the antenna pattern tuner 722 to adjust the radiation pattern of the antenna 702 based on the radiation pattern used by the communication circuitry 704.

[0083] The above specification, examples, and data provide a description of the devices, processes and methods of the disclosure. Because many examples can be made without departing from the spirit and scope of the disclosure, this specification sets forth some of the many possible example approaches and implementations.

Claims

CLAIMS What is claimed is:

1. An electronic device, comprising: an antenna; communication circuitry to receive radio frequency (RF) signals on the antenna;

RF harvest circuitry to generate electrical energy from the RF signals received on the antenna; and a switch to: couple the antenna to one of the communication circuitry and the RF harvest circuitry in a first state; and couple the antenna to the other of the communication circuitry and the RF harvest circuitry in a second state.

2. The electronic device of claim 1 , wherein the switch is to couple the antenna to the communication circuitry when the communication circuitry is active.

3. The electronic device of claim 1 , wherein the switch is to couple the antenna to the RF harvest circuitry when the communication circuitry is inactive.

4. The electronic device of claim 1 , wherein the communication circuitry comprises a control pin, wherein the switch is to couple the antenna to the RF harvest circuitry when the control pin for the communication circuitry is in an off state.

5. The electronic device of claim 1 , wherein the switch is to couple the antenna to the RF harvest circuitry when the RF signals are within a frequency band.

6. An electronic device, comprising: a first antenna; a second antenna; communication circuitry to transmit first radio frequency (RF) signals on the first antenna;

RF harvest circuitry to generate electrical energy from second RF signals received on the first antenna; and a switch to selectively couple the first antenna to one of the communication circuitry and the RF harvest circuitry based on communication circuitry activity and second antenna activity.

7. The electronic device of claim 6, wherein the switch is to couple the first antenna to the RF harvest circuitry when the communication circuitry is inactive and the second antenna is transmitting the second RF signals.

8. The electronic device of claim 6, wherein the first antenna is to be used for a first radio technology and the second antenna is to be used for a second radio technology.

9. The electronic device of claim 6, further comprising an antenna frequency tuner coupled to the first antenna, wherein the antenna frequency tuner is to adjust a first antenna frequency band based on a second antenna frequency band in response to the switch coupling the first antenna to the RF harvest circuitry.

10. The electronic device of claim 6, further comprising an antenna pattern tuner to adjust a radiation pattern of the first antenna in response to the switch coupling the first antenna to the RF harvest circuitry.

11. An electronic device, comprising: an antenna; communication circuitry to transmit first radio frequency (RF) signals on the antenna; RF harvest circuitry to generate electrical energy from second RF signals received on the antenna; a switch to selectively couple the antenna to one of the communication circuitry and the RF harvest circuitry; and a controller to: monitor a communication circuitry state; and adjust the switch to couple the antenna to one of the communication circuitry and the RF harvest circuitry based on the communication circuitry state.

12. The electronic device of claim 11 , wherein the controller is to: determine that the communication circuitry is in an idle state; and adjust the switch to couple the antenna to the RF harvest circuitry in response to determining that the communication circuitry is in the idle state.

13. The electronic device of claim 11 , wherein the controller is to: determine a multiple-input multiple-output (MIMO) state of the antenna; and adjust the switch to couple the antenna to the RF harvest circuitry based on the MIMO state of the antenna.

14. The electronic device of claim 11 , wherein the controller is to: monitor an RF harvest circuitry state; determine an RF harvest priority based on the RF harvest circuitry state and the communication circuitry state; and adjust the switch to couple the antenna to the RF harvest circuitry based on the RF harvest priority.

15. The electronic device of claim 11 , wherein the controller is to: monitor activity of an RF signal source; determine an RF harvest priority based on the RF signal source activity and the communication circuitry state; and adjust the switch to couple the antenna to the RF harvest circuitry based on the RF harvest priority.