CN108418643B

CN108418643B - Device, method and system for detecting short beacon signal

Info

Publication number: CN108418643B
Application number: CN201810217954.6A
Authority: CN
Inventors: 约翰·S·沃利; 安杰尔·阿图罗·波洛
Original assignee: Avago Technologies General IP Singapore Pte Ltd
Current assignee: Avago Technologies International Sales Pte Ltd
Priority date: 2014-05-23
Filing date: 2015-05-22
Publication date: 2021-06-18
Anticipated expiration: 2035-05-22
Also published as: CN105099584B; HK1215110A1; CN108418643A; CN105099584A

Abstract

The disclosure relates to power receiving unit short beacon detection. An apparatus for detecting short beacon signals comprising: a Power Receiving Unit (PRU) to receive short beacon signals from one or more Power Transmitting Units (PTUs). Asserting an active load level portion for detection by the one or more PTUs in response to the short beacon signal. Once the active load level portion is asserted, a change in reflected impedance associated with the PRU is enabled to be detected when measured by at least one of the one or more PTUs.

Description

Device, method and system for detecting short beacon signal

Related information of divisional application

The scheme is a divisional application. The parent of this division is the invention patent application with application date of 2015, 5-month, 22-day, application number of 201510266981.9 and the name of "power receiving unit short beacon detection".

Cross Reference to Related Applications

This application claims priority to U.S. provisional patent application 62/002,690 filed on 23/5 2014, U.S. patent application 14/714,139 filed on 15/5 2015, and 62/153,462 filed on 27/4 2015, the entire contents of which are incorporated herein by reference.

Technical Field

The present technology relates generally to a charging circuit, and in particular, to detecting a power-receiving unit (PRU) by a power-transmitting unit (PTU) during a short beacon (short beacon).

Background

Wireless power transfer from a Power Transmitting Unit (PTU) to a Power Receiving Unit (PRU) may be achieved without the need for artificial conductors. This mode of power transfer may be useful in many situations, for example, when interconnecting wires is inconvenient, hazardous, or impossible. Cross-connect occurs when a Radio Frequency (RF) control channel, such as bluetooth low energy (BTLE), forms a connection between the wrong PTU-PRU pair. Currently, there is a mechanism for detecting impedance changes of a PRU by triggering a discovery window of 105ms for an initial advertisement of the PRU. Another mechanism uses BTLE Received Signal Strength Indication (RSSI) filtering to try and associate an advertising transmitter with the proximity of the charging surface.

In some cases, it is quite difficult or impossible to detect PRU during short beacons by impedance detection methods, and this remains an unresolved problem. Some solutions do not require that the PTU must use short beacons to detect PRUs. Other solutions require and test PTUs that can detect changes in the minimum reflected impedance of an open substrate, which are not clear in the way reflected impedance is generated. It has also been proposed to require and test PTUs with the function of detecting the reflected impedance of a particular PRU. The PTU periodically (e.g., every 1/4 seconds) transmits a short (e.g., 10msec long) beacon to detect the presence of a PRU, and once the presence of a PRU is reliably detected, the PTU may further power its coil and transmit a stronger and longer charging pulse (e.g., a long beacon). The PTU saves a lot of energy since long beacons do not need to be transmitted frequently.

Disclosure of Invention

According to an aspect of the present invention, there is provided an apparatus for detecting a short beacon signal, the apparatus comprising: a Power Receiving Unit (PRU) configured to receive the short beacon signal from one or more Power Transmitting Units (PTUs); and an active load level portion (active load level) configured to be asserted (asserted) in response to the short beacon signal for detection by the one or more PTUs, wherein the active load level portion, once asserted, produces a detectable change in reflected impedance (reflected impedance) associated with the PRU as measured by at least one of the one or more PTUs.

Wherein the PRU includes a semiconductor chip including an input port coupled with a PRU coil and an output port coupled with a charging circuit.

Wherein the active load level section comprises two first passive reactive elements, and wherein each of the two first passive reactive elements is coupled between a port of the input ports of the PRU and a switch configured to be operable to couple a respective one of the two first passive reactive elements to ground potential.

Wherein the two first passive reactive elements comprise capacitors; the switch comprises a Field Effect Transistor (FET) implemented in the semiconductor chip; the FET is configured to be turned on by a first signal that may be received from a rectifier circuit of the PRU; the FET is configured to be turned off in response to a second signal; providing, by software, the second signal, wherein the assertion of the active load level section occurs concurrently with transmission of a Radio Frequency (RF) signal indicative of the presence of the PRU; and the RF signal comprises a Bluetooth low power (BTLE) signal.

The apparatus according to the present invention, further comprising a second passive reactive element coupled to the input port of the PRU, wherein the second passive reactive element comprises an inductor, and wherein the two first passive reactive elements comprise two capacitors, and wherein the switch is operable to couple a respective one of the two capacitors to ground potential in response to a delay signal, wherein the delay signal is delayed with respect to a start time of the short beacon, and wherein the delay signal is provided by software.

The apparatus according to the present invention, further comprising a second passive reactive element coupled to the input port of the PRU, wherein the second passive reactive element comprises a capacitor, and wherein the two first passive reactive elements comprise two inductors, and wherein the switch is operable to couple a respective one of the two inductors to ground potential in response to a delay signal, wherein the delay signal is delayed with respect to a start time of the short beacon, and wherein the delay signal is provided by software.

Wherein the switch is implemented by an off-chip Bipolar Junction Transistor (BJT), wherein the short beacon amplitude is large enough to turn on the BJT, wherein the BJT is configured to be turned off by a delay signal, wherein the delay signal is provided by software.

Wherein the switch is implemented by an off-chip Bipolar Junction Transistor (BJT), wherein the PRU retains sufficient power to operate the BJT, wherein the apparatus further comprises a comparator configured to compare a voltage on one of the input ports of the PRU to a threshold voltage and, in response to determining that the voltage is greater than the threshold voltage, trigger transmission of a Bluetooth Low Power (BTLE) signal to the one or more PTUs to cause at least one of the one or more PTUs to emit a long beacon.

Wherein the active load level section is coupled in series with a relay, wherein the relay is configured to turn off the active load level section when the PRU is awakened, wherein an amplitude of the short beacon does not limit operation of the apparatus.

Wherein the PRU is configured to select one of the one or more PTUs based on a strength of a signal received from the one or more PTUs during a connection process; the PRU is configured to request each of the one or more PTUs to send an indicator to the PRU indicating a strength of a reflected impedance detected by the PTU; and the PRU is configured to select one of the one or more PTUs to receive power from a PTU of the one or more PTUs that detects a highest reflected impedance from the PRU based on the indicator received from the one or more PTUs.

Wherein the PRU is in close proximity to one or more coils of a coil array of a PTU of the one or more PTUs, the PRU configured to receive power from a selected coil of the coil array, the selected coil comprising one of the coils of the coil array operable to generate a highest reflected impedance in the PTU of the one or more PTUs and to be powered by the PTU of the one or more PTUs to charge the PRU.

According to another aspect of the present invention, there is provided a method of providing an apparatus for detecting a short beacon signal, the method comprising: providing a Power Receiving Unit (PRU) configured to receive the short beacon signal from one or more Power Transmitting Units (PTUs); and providing an active load level section configured to be asserted in response to the short beacon signal for detection by the one or more PTUs, wherein the active load level section is configured to produce a detectable change in the reflected impedance of the PRU, measured by at least one of the one or more PTUs, once asserted.

Wherein the PRU comprises a semiconductor chip comprising an input port coupled with a PRU coil and an output port coupled with a charging circuit, wherein providing the active load level section comprises providing two first passive reactive elements and coupling each of the two first passive reactive elements between a switch and a port in the input port of the PRU, wherein the switch is configured to be operable to couple a respective one of the two first passive reactive elements to ground potential.

Wherein providing the two first passive reactive elements comprises providing two capacitors; providing the switch comprises providing a Field Effect Transistor (FET) implemented in the semiconductor chip; assertion of the active load level section occurs concurrently with transmission of a Radio Frequency (RF) signal indicating presence of the PRU; the RF signal comprises a Bluetooth Low Power (BTLE) signal; and the method further comprises: configuring the FET to turn on by a first signal receivable from a rectifier circuit of the PRU; configuring the FET to be off in response to a second signal; and providing the second signal by software.

According to the method of the present invention, further comprising providing a second passive reactive element coupled to the input port of the PRU, wherein providing the second passive reactive element comprises providing an inductor, and wherein providing the two first passive reactive elements comprises providing two capacitors, and wherein the switches are operable to couple respective ones of the two capacitors to ground potential in response to a delay signal, wherein the delay signal is delayed with respect to a start time of the short beacon, and wherein the delay signal is provided by software.

According to the method of the present invention, further comprising providing a second passive reactive element coupled to the input port of the PRU, wherein providing the second passive reactive element comprises providing a capacitor, and wherein providing the two first passive reactive elements comprises providing two inductors, and wherein the switch is operable to couple a respective one of the two inductors to ground potential in response to a delay signal, wherein the delay signal is delayed with respect to a start time of the short beacon, and wherein the delay signal is provided by software.

The method according to the invention further comprises: setting the switch includes setting an off-chip Bipolar Junction Transistor (BJT), wherein the short beacon amplitude is large enough to turn on the BJT, wherein the BJT is configured to be turned off by a delay signal, wherein the delay signal is controlled by software.

Wherein setting the switch comprises setting an off-chip Bipolar Junction Transistor (BJT), wherein the PRU retains sufficient power to operate the BJT, wherein the method further comprises setting a comparator configured to compare a voltage on one of the input ports of the PRU with a threshold voltage and, in response to determining that the voltage is greater than the threshold voltage, trigger transmission of a Bluetooth Low Power (BTLE) signal to the one or more PTUs to cause at least one of the one or more PTUs to emit a long beacon.

Wherein the method further comprises configuring the PRU to: selecting one of the one or more PTUs based on a strength of a signal received from the one or more PTUs during a connection process; requesting each of the one or more PTUs to send an indicator to the PRU indicating a strength of a reflected impedance detected by the PTU; selecting one of the one or more PTUs to receive power from a PTU of the one or more PTUs that detected a highest reflected impedance from the PRU based on the indicator received from the one or more PTUs; and receiving power from a selected coil of a coil array of a PTU of the one or more PTUs, wherein the PRU is in close proximity to one or more coils of the coil array and the selected coil comprises one of the coils of the coil array operable to generate a highest reflected impedance in the PTU of the one or more PTUs and to be powered by the PTU of the one or more PTUs to charge the PRU.

According to yet another aspect of the invention, there is provided a system comprising: a Power Transmit Unit (PTU) coupled to the one or more Transmit (TX) coils; a Power Receiving Unit (PRU) configured to receive power through magnetic coupling with at least one of the one or more Transmit (TX) coils; and an active load level section configured to be asserted in response to a short beacon signal received from the PTU, wherein the PTU is configured to detect a change in reflected impedance associated with the PRU in response to assertion of the active load level section.

Drawings

Certain features of the technology are set forth in the appended claims. However, for the purpose of illustration, several embodiments of the present technology are set forth in the following figures.

1A-1B are high-level diagrams illustrating an example system for wireless transmission of electrical power according to one or more embodiments;

fig. 2A-2C illustrate an example of an apparatus for detecting a Power Receiving Unit (PRU) short beacon using a load capacitor and corresponding timing diagrams in accordance with one or more embodiments;

fig. 3A-3B illustrate an example of an apparatus for detecting a PRU short beacon using a hybrid matching circuit in accordance with one or more embodiments;

fig. 4 illustrates another example of an apparatus for detecting PRU short beacons using a switched hybrid matching circuit in accordance with one or more embodiments;

fig. 5 illustrates one example of an apparatus for detecting PRU short beacons using a switched hybrid matching circuit with external switches in accordance with one or more embodiments;

fig. 6 illustrates one example of an apparatus for detecting a PRU during short beacons using a switched hybrid matching circuit employing an external relay, in accordance with one or more embodiments;

fig. 7 illustrates another example of an apparatus for detecting a PRU during short beacons using a switched hybrid matching circuit with an external switch in accordance with one or more embodiments;

fig. 8 illustrates another example of an apparatus for detecting a PRU during short beacons using a switched hybrid matching circuit with an external switch in accordance with one or more embodiments;

fig. 9 illustrates one example of a method for detecting PRUs during short beacons in accordance with one or more embodiments; and

fig. 10 illustrates one example of a wireless communication device employing features of the present technology in accordance with one or more embodiments.

Detailed Description

The detailed description set forth below is intended as a description of various configurations of the present technology and is not intended to represent the only configurations in which the present technology may be practiced. The accompanying drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the present technology. It will be apparent, however, to one skilled in the art that the present technology is not limited to the specific details set forth herein, and may be practiced using one or more embodiments. In one or more examples, well-known structures and elements are shown in block diagram form in order to avoid obscuring the concepts of the present technology.

In one or more aspects of the present technology, methods and embodiments are described for assisting a Power Receiving Unit (PRU) with short beacon signal detection. The present techniques enable assertion of an active load level portion (e.g., an active load pulse) by a PRU, which allows a Power Transmitting Unit (PTU) to detect a change in the reflected impedance of the PRU during a short beacon as a signature of the PRU present and to be available to receive power from the PTU. Without reliable knowledge of the presence of PRUs for receiving transmitted energy, allowing the detection of PRUs during short beacons results in significant energy savings for the PTU due to not powering its coil.

Fig. 1A-1B are high-level diagrams illustrating

example systems

100A and 100B for wireless transmission of electrical power, in accordance with one or more embodiments of the present technology. The system 100A depicted in fig. 1A shows a single-coil PTU and includes a magnetic coil 120 powered by a circuit (e.g., an analog module) 110. The system 100A further includes a bluetooth low energy (BTLE) circuit and a CPU that share the same, represented by a BTLE + CPU module 130. The BTLE circuitry includes known RF and baseband radios for transmitting and receiving RF signals including BTLE signals. The CPU controls the operation of the analog module 110, for example, based on signals received by the BTLE circuit. The signals received by the BTLE circuit include, for example, signals from the PRU 150.

The system 100B depicted in FIG. 1B shows a multi-coil PTU and includes a plurality of magnetic coils, such as 120-1, 120-2, and 120-3, coupled to and powered by a plurality of respective analog modules, such as 110-1, 110-2, and 110-3, and sharing a common BTLE + CPU module 130. In some embodiments, the magnetic coils may form an array of magnetic coils, e.g., made up of a plurality of die (tile) configurations. Each die configuration may include a two-dimensional configuration of coils (e.g., 2 x 2 or 3 x 3, etc.). The PTU of system 100B needs to detect which coil(s) of the magnetic coils are in close proximity to the PRU and is powered only by that coil(s) in order to be able to save energy consumption. The use of short beacons to detect the presence of PRUs is discussed in more detail herein.

The present techniques can allow the PTU to detect the presence of a PRU by detecting a change in the Reflected Impedance (RI) associated with the PRU. In normal magnetic interaction, a change in reflected impedance may be induced at the PTU, for example, by increasing the metal located on the PRU or increasing the ferrite. The present technique includes impedance changes caused by asserting an impedance load, such as a hybrid matched impedance. The PTU coil impedance for a single PRU with hybrid matching is given by:

wherein: r1 PTU coil resistance, L1 PTU coil self inductance, L2 PRU self inductance, Cs2 and Cp2 PRU matching capacitance, ZL PRU load (complex variable), R2 PRU coil resistance, Re _ PTU real resistance (positive and usually very small) to eddy current losses generated by eddy currents in the PTU housing and shield and around the ferrite, Re _ PRU real resistance (positive and small, in the range of 20 to 200 milliohms) to eddy current losses generated by eddy currents in the PRU, Xe _ PTU reactance to eddy current losses generated by eddy currents in the PTU housing and shield and around the ferrite. This reactance is typically small, e.g., < <1 ohm. The polarity of this reactance depends on the PTU material conducting the eddy currents. The reactance is inductive if there is little metal and mainly ferrite. With a large amount of metal and few ferrites, the reactance is capacitive. Xe _ PRU is the reactance of the eddy current loss generated by the eddy current within the PRU. This reactive Xe _ PRU may be large (e.g., a few ohms). The polarity of this reactance depends on the PRU material. The reactance is inductive if there is little metal and mainly ferrite. With many metals and few ferrites, the reactance is capacitive. K12-coupling coefficient. The term k12 is the reflected impedance of the conductive load at the PRU. If ZL is a capacitive load, the coupling coefficient is inductance. If ZL is a resistor, the coupling coefficient has a small reactance if properly tuned.

The parameters Re _ PRU and Xe _ PRU may be detected by high sensitivity detection circuitry used at the PTU while performing correlation over multiple samples. In this process, there is always a resistive loss if there is any real loss. The possibility that the reactance terms (e.g., Xe _ PRU and Xe _ PRU) can be eliminated is small. Although not normally possible, the cancellation reactance term affects the reliability of the detection of PRU reflected impedance changes. As will be discussed herein, the present techniques can allow PRUs to provide more reliable reflected impedance changes by asserting the active load level portion and, in certain embodiments, combining it with the transmission of RF signals (e.g., BTLE signals).

Fig. 2A-2C illustrate an example of an apparatus 200A for detecting a Power Receiving Unit (PRU) during a short beacon period using a load capacitor and a corresponding timing diagram 200C in accordance with one or more embodiments of the present technique. The apparatus 200A includes: PRU200 (e.g., PRU chip); the PRU is coupled to a PRU inductor L2 (e.g., a PRU magnetic coil) at

input nodes

202 and 204; and a matching capacitor C2s in series with the inductor L2. Further, PRU200 may assert active load level sections, e.g., levels formed by capacitors C1 and C2 (e.g., first passive reactive elements) coupled between

nodes

202 and 204 and

nodes

206 and 208 of PRU 200. As shown in fig. 2B, among other circuits, PRU200 includes a rectifier circuit 210 and switches S1 and S2. Rectifier circuit 210 rectifies and filters input pulses received at

input nodes

202 and 204 of the PTU (e.g., 100A of fig. 1A) and provides energy to a charger circuit (not shown for simplicity) of a device (e.g., a handheld communication device such as a cell phone, tablet, etc.) that includes apparatus 200A.

To be able to turn on the rectifier circuit 210, the input pulse needs to provide a voltage amplitude equal to at least two diode drops. Also, the rectifier circuit 210 must be able to activate the switches S1 and S2 in order to assert the impedance load (e.g., the capacitors C1 and C2). In some embodiments, the switches S1 and S2 are implemented using Field Effect Transistors (FETs), and the rectifier circuit 210 must provide sufficient voltage (e.g., 2.8V) to turn the FETs on. Once turned on, the switches connect

nodes

206 and 208 to ground potential. It should be understood that when switches S1 and S2 are open, capacitors C1 and C2 are not part of the reflected impedance of the PRU and only surge current is allowed to pass through them when the capacitors are connected to ground potential through activated switches (e.g., FETs) S1 and S2.

FIG. 2C shows a circuit including a reflected impedance (R)_ref) A graph 220 of amplitude versus time and a graph 230 of short beacon current are shown as timing diagrams 200C. The first pulse 222 is generated by the inrush current through the capacitor of the rectifier circuit 210. The short beacon current pulses 230 transmitted by the PTU cause an inrush current that is strong enough not only to turn on the rectifier circuit 210 but also to activate the switches S1 and S2 through the rectifier circuit 210. Within a time interval T2 (e.g., 5msec) beginning with a short beacon current pulse 230 having a duration of T1 (e.g., about 10 msec), the first pulse 222 is followed by a second pulse 224. The disconnection switches S1 and S2 may be controlled by the termination of the short beacon or by the PRU, e.g., by software. Even when the reactive impedance is cancelled as described above, as represented by the second pulse 224, the change in reflected impedance sensed by the PTU due to the asserted load can be easily and reliably detected by the PTU.

Fig. 3A-3B illustrate examples of

apparatuses

300A and 300B for detecting PRUs during short beacons using hybrid matching circuitry in accordance with one or more embodiments of the present technology. In some embodiments, a hybrid match can be used to induce a load (e.g., C2p of fig. 3A) even when the PRU200 cannot be turned on by the short beacon transmitted by the PTU. Regardless of how strong the short signal is, the parallel capacitance C2p is added to the reflected impedance of the PRU. This solution is effective and has low cost, but could pose some potential problem if C2p is made too large. For example, the voltage Received (RX) at

nodes

202 and 204 of PRU200 may become too high, which requires the PRU coil to become scaled down (e.g., less than L2) if C2p becomes too high, which may cause efficiency losses. Also as C2p increases, the term Zrx _ in reflected impedance increases, which would make Zrx _ in undesirable for load regulation.

Fig. 3B shows an apparatus 300B in which an inductive load (e.g., C2p) is inserted before the matching capacitor C2 s. Device 300B has similar advantages when operating independently of the strength of the short beacon received from the PTU. The capacitance C2p in fig. 3B cannot be made too large for similar reasons as explained in fig. 3A.

Fig. 4 illustrates an example of an apparatus 400 for detecting PRU short beacons using a switched hybrid matching circuit in accordance with one or more embodiments of the present technology. The apparatus 400 shown in fig. 4 is similar to the apparatus 200A of fig. 2A, except that a fixed reactive load L3 (e.g., a second passive reactive element) is added in the PRU. There is an inductive effect of the fixed reactive load L3 in the reflected impedance of the PRU starting from the short beacon current pulse 230 of fig. 2C. In other words, the inductive load level effect of the reactive load L3, which is located on the reflected impedance of the PRU, is immediately applied, which allows the PTU to use short beacons for very short durations (e.g., 1 msec). For this solution, a short beacon of very short duration (e.g., 1msec) need not be able to turn on the rectifier circuit (e.g., 210 of fig. 2B). Upon detection of the device 400 by the PTU, the effect of the reactive load L3 must be cancelled at a later time. This role is served by the capacitances C1 and C2 (e.g., the first passive reactive element), e.g., software controlled signals (e.g., delay signals) assert these capacitances at the appropriate times and the capacitances cancel the effect of the reactive load L3. Apparatus 400 has the advantage of being able to operate with short beacons of short duration (e.g., less than a few msec, e.g., 1msec) and small amplitude (e.g., less than two diode drops), which allows the PTU to save power consumption. In some embodiments, the capacitors C1 and C2 are replaced by inductive elements and the reactive load L3 may be replaced by capacitive elements.

Fig. 5 illustrates an example of an apparatus 500 for detecting PRUs during short beacons using a switched hybrid matching circuit employing external switches in accordance with one or more embodiments. If the battery of the device including apparatus 500 is sufficiently charged for system operation, the load may be asserted through an external switch. In some embodiments, the active load level section formed by capacitors C1 and C2 is switched by external Bipolar Junction Transistors (BJTs) T1 and T2. Transistors T1 and T2 may be controlled by signal 502, e.g., a General Purpose Input Output (GPIO) signal from PRU200 or from a processor. In one or more implementations, the comparator 510 may detect a small signal at the input node 202 of the PRU200 by comparing the signal at the input node 202 to a small (e.g., 0.1V) threshold voltage (Vth), and in response to the detection, generate a signal 512 that causes the processor or BTLE module to transmit an advertisement to the PTU. The PTU needs to look for BTLE advertisements and then start long beacon processing in response to the advertisements received from the BTLE module. This solution significantly reduces cost and may significantly save PTU power consumption, since the PTU only starts powering its coils when the PRU200 is known to be present. In one or more embodiments, if comparator 510 is powered by an external battery, apparatus 500 may begin charging from a fully discharged state of the device (e.g., the battery is dead).

Fig. 6 illustrates an example of an apparatus 600 for detecting a PRU during short beacon periods using a switched hybrid matching circuit employing an external relay 610 in accordance with one or more embodiments of the present technology. This solution adds a passive reactance that can load the PRU during short beacon signals but can disconnect the passive load when the device 600 is awakened. The short beacon signal may have any amplitude. The relay switch 610 may be controlled by a GPIO signal 612 from the PRU200 or from a processor. The relay 610 is closed at startup and can assert a capacitance C between

nodes

202 and 204. Thus, at the beginning of the short beacon, the change in reflected impedance can be detected by the PTU. When the device 600 wakes up, the signal 612 opens the capacitor C1 by opening the relay switch.

Fig. 7 illustrates an example of an apparatus 700 for detecting PRUs during short beacons using a switched hybrid matching circuit employing external switches in accordance with one or more embodiments. This solution adds a passive reactance that can load the PRU during short beacon signals, but can disconnect the passive load when the device 600 is awakened. The short beacon signal requires sufficient amplitude (e.g., about 1V) to open an external switch formed by a BJT (e.g., PNP transistor) to be able to assert the impedance loads (e.g., capacitors C1 and C2). BJTs T1 and T1 are turned off by default by GPIO terminals and may be turned on by signal 710 from the rectifier circuit of PRU200 for a short time (e.g., a few msec) after the start time of the short beacon.

Fig. 8 illustrates an example of an apparatus 800 for detecting a PRU during a short beacon period using a switched hybrid matching circuit employing an external switch in accordance with one or more embodiments of the present technology. Device 800 is similar to device 700, and switches S1 and S2 may be FETs or BJTs, and are also operated by PRU200 to be able to assert capacitances C1 and C2 in response to a short beacon having sufficient amplitude. The device 800 is further operable to transmit an advertisement (e.g., BTLE signal) 810 while the active load is asserted. The PTU monitor is used to monitor impedance changes 820 that occur while receiving the advertisement 810 to ensure that the PRU200 is present within the PTU coverage area. The PTU may reject advertisements that do not accompany load changes (e.g., 820).

Returning to the system 100B of FIG. 1B, the PRU 150 is in close proximity to one or more coils (e.g., 102-1 and 102-2) of the coil array of the PTU. The PRUs 150 receive power from selected coils of a coil array operable to generate the highest reflected impedance within and powered by the respective PTU to charge the PRU 150. In one or more implementations, PRU 150 may receive short beacons from multiple PTUs. In this case, the PRU 150 may select one PTU according to the strength of a signal received from the PTU during the connection process. Alternatively, PRU 150 may request that each PTU send PRU 150 an indicator indicating the strength of the reflected impedance detected by this PTU. PRU 150 may then select one PTU based on the indicator received from the PTU to receive the received power from the PTU detected from the highest reflected impedance of PRU 150.

Fig. 9 illustrates one example of a method 900 for detecting PRU short beacons in accordance with one or more implementations of the present technology. According to the method 900, a PRU (e.g., 200 of fig. 2A) is configured to be able to receive a short beacon signal (e.g., 230 of fig. 2C) from one or more PTUs (e.g., 100A of fig. 1A) (910). The active load level sections (e.g., C1 and C2 of fig. 2A) are arranged to enable assertion (920) of detection by one or more PTUs in response to PRU signaling during a short beacon period. Once asserted, the active load level portion is configured to become a change in the reflected impedance of the PRU (e.g., 224 of fig. 2C) as measured by at least one of the one or more PTUs.

Fig. 10 illustrates one example of a wireless communication device 1000 employing features of the present technology in accordance with one or more implementations of the present technology. The wireless communication device 1000 includes a Radio Frequency (RF) antenna 1010, a receiver 1020, a transmitter 1030, a baseband processing module 1040, a memory 1050, a processor 1060, a Local Oscillation Generator (LOGEN)1070, and a power supply 1080. In various implementations of the present technology, one or more of the blocks represented in fig. 10 may be integrated on one or more semiconductor substrates. For example, blocks 1020 through 1070 may be implemented within a single chip or a single system-on-a-chip or may be implemented within a multi-chip chipset.

The RF antenna 1010 may be adapted to transmit and/or receive RF signals (wireless signals) over a wide range of frequencies. Although a single RF antenna 1010 is shown, the present techniques are not limited thereto.

The receiver 1020 comprises suitable logic and/or code that may be operable to receive and process signals from the RF antenna 1010. Receiver 1020 may be operative to, for example, amplify and/or downconvert received wireless signals. In various embodiments of the present technology, the receiver 1020 is operable to cancel noise in the received signal and may be linear over a wide range of frequencies. In this manner, receiver 1020 is adapted to receive signals in accordance with various wireless standards, Wi-Fi, WiMAX, Bluetooth, and various cellular standards.

The transmitter 1030 may comprise suitable logic and/or code that may be operable to process and transmit signals from the RF antenna 1010. The transmitter 1030 may be operable to up-convert a baseband signal to an RF signal and amplify the RF signal, for example. In various embodiments of the present technology, the transmitter 1030 may be operable to upconvert and amplify baseband signals processed according to various wireless standards. Examples of such standards include Wi-Fi, WiMAX, Bluetooth, and various cellular standards. In various embodiments of the present technology, the transmitter 1030 is operable to provide a signal for further amplification by one or more power amplifiers.

The duplexer 1012 provides isolation within the transmission band to avoid saturation of the receiver 1020 or damage to components of the receiver 1020 and to relax one or more design requirements of the receiver 1020. Also, the duplexer 1012 may be noise attenuation within the receive band. The duplexer may operate within multiple frequency bands of various wireless standards.

The baseband processing module 1040 comprises suitable logic, circuitry, interfaces and/or code that may be operable to perform processing of baseband signals. The baseband processing module 1040 may, for example, analyze received signals and generate control and/or feedback signals for configuring various elements of the wireless communication device 1000, such as the receiver 1020. The baseband processing module 1040 is operable to encode, decode, transcode, modulate, demodulate, encrypt, decrypt, scramble, descramble, and/or process data according to one or more wireless standards.

The processor 1060 may comprise suitable logic, circuitry, and/or code that may process data and/or control operation of the wireless communication device 1000. In this regard, the processor 1060 can be permitted to provide control signals to various other portions of the wireless communication device 1000. Processor 1060 also controls the transfer of data between different portions of wireless communication device 1000. Further, the processor 1060 may implement an operating system or execute code to manage the operation of the wireless communication device 1000.

The memory 1050 may comprise suitable logic, circuitry, and/or code that may store various types of information such as received data, generated data, code, and/or configuration information. Memory 1050 includes, for example, RAM, ROM, flash memory, and/or magnetic memory. In various embodiments of the present technology, memory 1050 may comprise RAM, DRAM, SRAM, T-RAM, Z-RAM, TTRAM, or any other storage medium.

The Local Oscillator Generator (LOGEN)1070 may comprise suitable logic, circuitry, interfaces and/or code that may be operable to generate one or more oscillating signals at one or more frequencies. LOGEN 1070 is operable to generate digital and/or analog signals. In this manner, the LOGEN 1070 is operable to generate one or more clock signals and/or sinusoidal signals. For example, characteristics of the oscillating signal, such as frequency and duty cycle, may be determined from one or more control signals from processor 1060 and/or baseband processing module 1040.

During operation, processor 1060 may configure various components of wireless communication device 1000 based on a wireless standard according to which it is desired to receive signals. The wireless signals may be received by the RF antenna 1010 and amplified and downconverted by a receiver 1020. The baseband processing module 1040 may perform noise estimation and/or noise cancellation, decoding, and/or demodulation of the baseband signal. In this manner, the information may be audio and/or video displayed to a user of the wireless communication device, data stored in memory 1050, and/or information affecting and/or enabling operation of the wireless communication device 1000. The baseband processing module 1040 may modulate, encode, and otherwise process audio, video, and/or control signals for transmission by the transmitter 1030 according to various wireless standards.

As described above, in some implementations of the present technology, the wireless communication device 1000 may include any device of the present technology (e.g., 200A of fig. 2A) for wirelessly receiving electrical power from a PTU (e.g., 100A of fig. 1A).

Those skilled in the art will appreciate that the various illustrative blocks, modules, components, elements, and methods described herein may be implemented as electronic hardware, computer software, or combinations of both. To illustrate this interchangeability of hardware and software, various illustrative blocks, modules, components, elements, and methods have been described above generally in terms of their functionality. Such functionality is implemented as hardware or software, depending upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application. The various elements and blocks may be arranged differently (e.g., arranged in a different order or divided in a different manner) without departing from the scope of the present technology.

As used herein, the phrase "at least one of" a series of items in the foregoing, as well as the terms "and" or "used to distinguish any item, generally modifies the list rather than individual components (e.g., each item) of the list. The phrase "at least one" does not require the selection of at least one of the various items listed; rather, the phrase is allowed to have a meaning that includes at least one of any one item and/or at least one of any combination of such items and/or at least one of the individual items. By way of example, the phrases "A, B and at least one of C" or "A, B or at least one of C" each mean that only a, only B, or only C is involved; A. any combination of B and C; and/or A, B and at least one of each of C.

Phrases such as "an aspect" do not imply that such aspect is essential to the technology or that such aspect applies to all configurations of the technology. The disclosure relating to this aspect may apply to all configurations or one or more configurations. An aspect may provide one or more examples of the disclosure. The phrase "an aspect" means one or more aspects and vice versa. Phrases such as "an embodiment" do not imply that such implementation is essential to the technology or that such implementation applies to all configurations of the technology. The disclosure relating to an embodiment may apply to all embodiments or one or more embodiments. Embodiments may provide one or more examples of the present disclosure. Phrases such as "an embodiment" may refer to one or more embodiments and vice versa. Phrases such as "configured" do not imply that such configuration is essential to the technology or that such configuration applies to all configurations of the technology. The disclosure relating to configurations may apply to all configurations or one or more configurations. Configurations may provide one or more examples of the present disclosure. A phrase such as "configuration" may refer to one or more configurations and vice versa.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" or "exemplary" is not to be construed as preferred or advantageous over other embodiments. Furthermore, to the extent that the terms "includes," "has," "having," and the like are used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

All structural and functional equivalents to the elements of the various aspects described in this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No component of any claim is to be construed in accordance with the 35u.s.c. § 112, sixth chapter 112, unless the component is explicitly stated using the phrase "means for …" or using the phrase "step for …" in a method claim.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. The term "some" means one or more unless explicitly stated otherwise. A positive pronoun (e.g., his) includes negative and neutral (e.g., her and it), and vice versa. Headings and subheadings, if any, are used for convenience only and do not limit the disclosure.

Claims

1. An apparatus for detecting a short beacon signal, the apparatus comprising:

a power receiving unit PRU configured to receive the short beacon signal from one or more power transmitting units PTU; and

circuitry comprising a switch configured to assert an active load level for detection by the one or more PTUs in response to the short beacon signal,

wherein the active load level is configured to generate, once asserted, a change in reflected impedance associated with the power receiving cell for detection by at least one of the one or more power transmitting cells, and wherein the short beacon signal comprises a pulsed signal having a time period T1, wherein the active load level is asserted during the T1 time period.

2. The apparatus of claim 1, wherein the circuit is configured to assert the active load level directly in response to the short beacon signal.

3. The apparatus of claim 1, wherein the short beacon signal causes an inrush current sufficient to activate the circuit to assert the active load level.

4. The apparatus of claim 1, wherein:

the PRU includes a rectifier circuit;

the switch may be activated by a first signal received from the rectifier circuit of the PRU.

5. The apparatus of claim 4, wherein the switch is configured to open in response to a second signal, the second signal provided by software, wherein the assertion of the active load level is concurrent with the transmission of a Radio Frequency (RF) signal indicating the presence of the PRU.

6. The apparatus of claim 5, wherein the RF signal comprises a Bluetooth low power BTLE signal.

7. The apparatus of claim 4, wherein the short beacon signal is configured to activate both the rectifier circuit and the switch to assert the active load level.

8. The apparatus of claim 1, further comprising a matching capacitance and a reactive load arranged in parallel with respect to the matching capacitance such that an inductive effect of the reactive load in a reflected impedance of the PRU exists at a beginning of the short beacon signal.

9. The apparatus of claim 8, wherein an inductive effect of the reactive load in a reflected impedance of the PRU is immediately applied such that the one or more PTUs are allowed to use a short beacon having a short duration relative to a time period of the short beacon signal.

10. The apparatus of claim 8, wherein the circuit comprises at least one first passive reactive element, wherein the at least one passive reactive element is asserted by a delay signal to cancel an inductive effect of the reactive load.

11. The apparatus of claim 1, wherein the circuit comprises at least one first passive reactive element, the apparatus further comprising at least one second passive reactive element that loads the PRU during the short beacon signal, wherein the at least one second passive reactive element is switched off when the apparatus wakes up.

12. The apparatus of claim 1, wherein the power receiving unit comprises a semiconductor chip including an input port coupled to a power receiving unit coil and an output port coupled to a charging circuit.

13. The apparatus of claim 12, wherein the active load level is configured to be provided by two first passive reactive elements, and wherein each of the two first passive reactive elements is coupled between a port of the input ports of the power receiving unit and a switch configured to be operable to couple a respective one of the two first passive reactive elements to a ground potential.

14. The apparatus of claim 1, wherein the active load level is provided by an active load level section coupled in series with a relay, wherein the relay is configured to turn off the active load level section when the power receiving unit is awakened, wherein an amplitude of the short beacon does not limit operation of the apparatus.

15. The apparatus of claim 1, wherein,

the power receiving unit is configured to select one of the one or more power transmitting units based on a strength of a signal received from the one or more power transmitting units during a connection process;

the power receiving unit is configured to request each of the one or more power transmitting units to send an indicator to the power receiving unit indicating the strength of the reflected impedance detected by that power transmitting unit; and

the power receiving unit is configured to select one of the one or more power transmitting units to receive power from a power transmitting unit of the one or more power transmitting units that detects a highest reflected impedance from the power receiving unit based on the indicator received from the one or more power transmitting units.

16. The apparatus of claim 1, wherein the power receiving unit is in close proximity to one or more coils of a coil array of a power transmitting unit of the one or more power transmitting units,

the power receiving unit is configured to receive power from a selected coil of the array of coils,

the selected coil comprises one of the coils of the coil array operable to generate a highest reflected impedance in the power transmitting unit of the one or more power transmitting units and to be powered by the power transmitting unit of the one or more power transmitting units to charge the power receiving unit.

17. A method for detecting a short beacon signal, the method comprising:

receiving the short beacon signals at a power receiving unit, PRU, from one or more power transmitting units, PTUs; and

asserting an active load level for detection by the one or more PTUs in response to the short beacon signal,

18. The method of claim 17, wherein the active load level is asserted directly in response to the short beacon signal.

19. The method of claim 17, wherein the PRU includes a rectifier and a switch coupled to the rectifier, and wherein both the rectifier and the switch are activated by the short beacon signal to assert the active load level.

20. The method of claim 17, wherein the power receiving unit comprises a semiconductor chip including an input port coupled with a power receiving unit coil and an output port coupled with a charging circuit, wherein providing the active load level comprises providing two first passive reactive elements and coupling each of the two first passive reactive elements between a switch and a port in the input port of the power receiving unit and coupling a respective one of the two first passive reactive elements to ground potential through the switch.

21. The method of claim 17, wherein the method further comprises configuring the power receiving unit to:

selecting one of the one or more power transmitting units based on a strength of a signal received from the one or more power transmitting units during a connection process;

requesting each of the one or more power transmitting units to send an indicator to the power receiving unit indicating a strength of a reflected impedance detected by the power transmitting unit;

selecting one of the one or more power transmitting units to receive power from a power transmitting unit of the one or more power transmitting units that detects a highest reflected impedance from the power receiving unit based on the indicator received from the one or more power transmitting units; and

receiving power from a selected coil of a coil array of a power transmitting unit of the one or more power transmitting units,

wherein the power receiving unit is in close proximity to one or more coils in the coil array, and

22. A system for detecting a short beacon signal, comprising:

a power transmitting unit PTU coupled to the one or more transmitting coils;

a power receiving unit PRU configured to receive power through magnetic coupling with at least one of the one or more transmitting coils; and

an active load level coupled to the power receiving unit and configured to be asserted in response to the short beacon signal received from the power transmitting unit,

wherein the power transmitting unit is configured to detect a change in reflected impedance associated with the power receiving unit in response to assertion of the active load level, and wherein the short beacon signal comprises a pulsed signal having a time period of T1, wherein the active load level is asserted for the T1 time period.

23. The system of claim 22, wherein the active load level is asserted directly in response to the short beacon signal.

24. The system of claim 22, wherein the PRU includes a rectifier and a switch coupled to the rectifier, and wherein both the rectifier and the switch are activated by the short beacon signal to assert the active load level.