ask modulation

Abstract

The present disclosure relates to ASK modulation. According to some embodiments of the present invention, a wireless power receiver that ASK impedance ramps is presented. A method of amplitude shift keying (ASK) modulation in a wireless power receiver includes initiating a transition of an ASK impedance from a first state to a second state, the ASK impedance coupled to a resonant circuit, the resonant circuit including a wireless power receive coil that receives a time-varying magnetic field; transitioning the ASK impedance from the first state to the second state according to the transition over a plurality of switching cycles of the time-varying magnetic field; and maintaining the second state.

Description

Technical Field

[0001] Embodiments of the present invention relate to wireless power systems, and more particularly to wireless power receivers with improved amplitude shift keying (ASK) modulation. Background Technology

[0002] Typically, a wireless power system includes a wireless power transmitter and a wireless power receiver. The transmitter drives a transmitter coil to generate a time-varying magnetic field; the receiver has a receiver coil positioned relative to the transmitter coil to receive power transmitted in the time-varying magnetic field. Many wireless power standards, such as the Qi standard, allow the wireless power signal between the transmitter and receiver coils to be used as an in-band communication channel. Specifically, the wireless power generator typically uses Frequency Shift Keying (FSK) modulation to transmit data to the wireless power receiver by modulating the frequency. The wireless power receiver typically uses Amplitude Shift Keying (ASK) modulation to transmit data to the wireless power transmitter by modulating the amplitude. This modulation is typically performed by modulating an impedance in the wireless power receiver that can be detected by the wireless power transmitter.

[0003] However, this ASK modulation can have adverse effects. Specifically, modulating the impedance of the resonant circuit formed by the receiver coil in this way can cause unintended current and voltage spikes in the receiver coil. These spikes can damage components of the wireless power receiver. Therefore, it is necessary to provide ASK modulation in the receiver while mitigating the harmful effects of this modulation. Summary of the Invention

[0004] According to some embodiments of the present invention, a wireless power receiver is provided that causes ASK impedance to transition at several switching cycles of a received time-varying magnetic field. The amplitude shift keying (ASK) modulation method in the wireless power receiver includes: initiating a transition of the ASK impedance from a first state to a second state, the ASK impedance being coupled to a resonant circuit including a wireless power receiving coil that receives the time-varying magnetic field; causing the ASK impedance to transition from the first state to the second state according to the transition at several switching cycles of the time-varying magnetic field; and maintaining the second state.

[0005] A wireless power receiver with ASK modulation includes: a rectifier coupled to receive wireless power from a resonant circuit including a receiver coil; an impedance control circuit coupled to an ASK impedance, the impedance control circuit being coupled to influence the impedance of the resonant circuit; and a controller coupled to the rectifier and the impedance controller, wherein the controller executes instructions to initiate a transition of the ASK impedance from a first state to a second state; transitions the ASK impedance from the first state to the second state according to transitions over multiple switching cycles of a time-varying magnetic field received by the resonant circuit; and maintains the second state.

[0006] These and other embodiments will be further discussed below with reference to the accompanying drawings. Attached Figure Description

[0007] Figure 1 The diagram illustrates a wireless power transmission system.

[0008] Figure 2 The diagram illustrates a wireless power transmitter.

[0009] Figure 3 The illustration shows a wireless power receiver according to some embodiments described herein.

[0010] Figure 4A , Figure 4B and Figure 4C The diagram illustrates current ASK modulation in a wireless power receiver.

[0011] Figure 5A and Figure 5B The illustrations depict some embodiments. Figure 3 ASK modulation is implemented in the wireless power receiver shown.

[0012] Figure 6A and Figure 6B The illustrations depict some embodiments. Figure 3 ASK modulation is implemented in the wireless power receiver shown.

[0013] Figure 7A and Figure 7B The illustrations depict some embodiments. Figure 3 ASK modulation is implemented in the wireless power receiver shown.

[0014] Figure 8 The illustrations depict some embodiments. Figure 3 The process implemented in the wireless power receiver shown. Detailed Implementation

[0015] In the following description, specific details describing some embodiments of the invention are set forth. However, it will be apparent to those skilled in the art that some embodiments may be practiced without some or all of these specific details. The specific embodiments disclosed herein are intended to be illustrative and not restrictive. Other elements, though not specifically described herein, may be implemented by those skilled in the art within the scope and spirit of this disclosure.

[0016] The description and accompanying drawings illustrating various aspects and embodiments of the invention should not be considered limiting; the claims define the protected invention. Various changes may be made without departing from the spirit and scope of this specification and the claims. In some cases, well-known structures and techniques have not been shown or described in detail so as not to obscure the invention.

[0017] Where feasible, elements and related aspects described in detail with reference to one embodiment may be included in other embodiments where they are not specifically shown or described. For example, if an element is described in detail with reference to one embodiment but not with reference to a second embodiment, that element may still be required to be included in the second embodiment.

[0018] The accompanying drawings are not to scale. The relative storage of components does not indicate actual dimensions. In the drawings, electrical connections are represented by solid dots, while simple crossing lines are not connected.

[0019] Figure 1 The diagram illustrates a system 100 for wireless power transfer. (See diagram for reference.) Figure 1 As shown, a wireless power transmitter 102 drives a coil 106 to generate a magnetic field. A power source 104 provides power to the wireless power transmitter 102. The power source 104 can be, for example, a battery-based power source or can be powered by alternating current (e.g., a standard power source of 50Hz, 240V or 60Hz, 120V). Typically, according to one of the wireless power standards, the wireless power transmitter 102 drives the coil 106 at a range of switching frequencies to emit a time-varying magnetic field. Embodiments according to this disclosure are applicable to any frequency, and it is feasible to use an electromagnetic coil to transmit power and / or information at any frequency, regardless of any standards that may exist.

[0020] like Figure 1 As further shown, the time-varying magnetic field generated by coil 106 induces a current in receiving coil 108, which results in power being received in wireless power receiver 110. Receiver 110 receives power from coil 108 and supplies power to load 112, which may be a battery charger and / or other components of a mobile device. Receiver 110 typically includes a rectifier to convert the AC power received by receiving coil 108 into DC power for load 112.

[0021] Several standards exist for wireless power transfer, including the Wireless Power Consortium (WPC) standard and the Qi standard. Under the Wireless Power Consortium (WPC) specification for Qi, resonant inductive coupling systems are used to charge a single device at its resonant frequency, typically operating between 80 kHz and 200 kHz. Most systems operate between 110 kHz and 148 kHz. In the Qi standard, coils 108 and 106 are located close to each other. In Qi standard systems, power levels increase as the frequency decreases, typically peaking around 100 kHz. Many Qi system designs modify the input voltage to achieve high power transfer. In some embodiments, a typical operating frequency is 127.7 kHz. Figure 1A general wireless power system 100 operating under any of these standards is described.

[0022] Figure 2 The diagram illustrates a wireless power transmitter 102. (See diagram for reference.) Figure 2 As shown, the transmit coil 106 of the wireless power transmitter 102 is coupled to the bridge 220 via a capacitor 224. The bridge 220, which may be a driver based on a half-bridge or full-bridge field-effect transistor (FET), is used to provide alternating current through the transmit coil 106. The alternating current through the transmit coil 106 provides a time-varying magnetic field or wireless power signal received by the receiver coil 108. The FETs of the bridge 220 are driven by a bridge driver 214, which is coupled to the gate of the FET. The bridge driver 214 is driven by a pulse width modulation (PWM) generator 212.

[0023] The PWM generator 212 receives signals from the controller 202, which determines the frequency and amplitude of the time-varying magnetic field emitted by the transmitting coil 106. As described above, Qi-compliant transmitters typically operate between 80 kHz and 200 kHz, with typical operating frequencies between 110 kHz and 148 kHz. A typical operating frequency is typically 127.7 kHz. However, embodiments of this disclosure can be applied to any operating frequency, including frequencies used in standards other than the Qi standard.

[0024] The power supply circuit 206 can receive input power to operate the wireless power transmitter 102. The power supply circuit 206 receives and accepts input voltage, such as... Figure 2 The same circuitry is also provided to bridge 220. Power supply circuitry 206 receives power from a source (e.g., a battery, rectified AC power, or other source) and provides voltage for the operation of other components of wireless power transmitter 102.

[0025] Controller 202 can be any circuit capable of executing instructions for performing the functions described in this disclosure. Controller 202 can include any processor, microprocessor, microcomputer, processing device, state machine, or other device capable of performing these functions. In most embodiments, controller 202 is coupled to memory 208, which includes volatile and non-volatile memory for storing data and executable instructions for operations of processor 202. Controller 202 can be further coupled to interface 204 for digital communication with other devices. Interface 204 can, for example, support I2C, GPIO, or other user interfaces. Thus, operating parameters and instructions can be loaded into memory 208 through these interfaces. Controller 202 can also be coupled to a receiver for sensor data in sensor 218. Sensor 218 includes analog filtering and an analog-to-digital converter (ADC) to provide operational data, such as, for example, coil current, temperature data, and other operational data monitored by controller 202.

[0026] like Figure 2 As further shown, in some embodiments, the controller 202 is coupled to an FSK modulator 216. The FSK modulator 216 provides a signal to the PWM generator 212 to modulate the frequency of the time-varying magnetic field emitted by the transmitting coil 106 to encode data via frequency shift keying. The FSK modulator 216 modulates the operating frequency of the time-varying magnetic field at a fundamental frequency f0 and a modulation frequency f0 over 256 consecutive period blocks. mod The data is encoded by shifting between bits to encode data containing logic "1" and logic "0" over an extended period of 512 frequency cycles. For example, logic "0" is encoded by frequency f. mod The 512-cycle encoding, while logic "1" is encoded by 256 consecutive cycles at frequency f0, where the 256 consecutive cycles at frequency f0 are at frequency f mod After 256 consecutive cycles.

[0027] like Figure 2Further shown, in some embodiments, controller 202 is coupled to receive data from ASK decoder 210. ASK decoder 210 may receive input from peak detector 222, which is coupled to transmit coil 106. In some embodiments, data is encoded at receiver 110 by modulating the load on receiver coil 108, the modulation manifesting as a measurable impedance change at transmit coil 106. Data is encoded as amplitude modulation using a 2 kHz clock frequency to achieve a data rate of 2 kbps. Data can be encoded using two narrow transitions as logic "1", while logic "0" is encoded using a wide transition. Thus, logic "1" is encoded as high impedance for half a data period and low impedance for the remaining half data period, while logic "0" is encoded as high impedance for both half data periods. In some embodiments, a contrastive scheme can be implemented where logic "1" is encoded as low impedance for the first half data period and high impedance for the second half data period, and logic "0" is encoded as low impedance for both half data periods. Using other data encoding schemes, the receiver 110 modulates the impedance of the resonant circuit including the receiving coil 108 between a high impedance state and a low impedance state.

[0028] Peak detector 222 measures the voltage or current at transmitter coil 106 and provides a signal to ASK decoder 210. ASK decoder 210 decodes the amplitude modulation data and provides the data to processor 202.

[0029] like Figure 2 As further shown, in some embodiments, the wireless power transmitter 102 may be formed on a single integrated circuit (IC) chip 222, with at least the controller 202, memory 208, interface 204, power supply circuitry 206, PWM generator 212, bridge driver 214, sensor circuitry 218, FSK modulator 216, and ASK decoder 210 formed on the single IC chip 222. Typically, due to the size and power requirements of these components, the bridge 220, peak detector 222, and transmit coil 106 are formed externally to the IC 222 and may be mounted on a printed circuit board together with the IC 222.

[0030] Figure 3 An example of a wireless power receiver 110 on which embodiments of the present invention can be implemented is illustrated. Figure 3 As shown, the receiver coil 108 is coupled to the rectifier 304 via a capacitor 330. The receiver coil 108 and the capacitor 330 can form an LC resonant circuit with impedance. The rectifier 304 can be a half-bridge or full-bridge rectifier typically formed by FETs. Figure 3As shown, the series coupling combination of receiving coil 108 and capacitor 330 is coupled between nodes AC1 and AC2.

[0031] Rectifier 304 is controlled by rectifier control 310. In some embodiments, rectifier control 310 controls the FET of rectifier 304 to synchronously receive and rectify a time-varying magnetic field received at receiving coil 108. Rectifier control 310 receives input signals from nodes BST1 and BST2. Node BST1 is coupled to node AC1 via capacitor 326. Node BST2 is coupled to node AC2 via capacitor 328. Rectifier control 310 may further receive signals from controller 302 to control rectifier 304. The received and rectified power is provided to DC power supply circuit 308, which provides various DC voltages, including an output voltage for driving load 112. DC power supply circuit 308 may include filtering and DC-DC conversion circuitry to provide various DC voltages.

[0032] The rectifier control 310 is also coupled to the FSK demodulator 314. The FSK demodulator 314 can determine the data that has been frequency-modulated into a wireless power signal, as described above. The FSK demodulator 314 provides the received demodulated data to the controller 302.

[0033] Controller 302 can be any circuit capable of executing instructions for performing the functions described in this disclosure. Controller 302 may include any processor, microprocessor, microcomputer, processing device, state machine, or other device capable of performing these functions. Controller 302 may be coupled to memory 318, which includes volatile and non-volatile memory for storing data and executable instructions for the operation of controller 302. Controller 302 may be further coupled to interface 316, which allows digital communication with other devices. Interface 316 may, for example, support I2C, GPIO, or other user interfaces. Thus, operating parameters and instructions can be loaded into memory 318 through these interfaces. Controller 302 may also be coupled to a receiver for sensor data in sensor 320. Sensor 320 includes analog filtering and an analog-to-digital converter (ADC) to provide operational data, such as, for example, coil current, temperature data, and other operational data for monitoring by controller 302.

[0034] The controller 302 is further coupled to the ASK modulator 306. The ASK modulator 306 is coupled via an ASK impedance device 322 to node AC1 and via an ASK impedance 324. The ASK modulator 306 can modulate the load on the receiving coil 108 by turning on and off impedances 322 and 324 in response to data to be transmitted received from the controller 302. According to an embodiment of this disclosure, the controller 302 controls the ASK modulator 306 such that impedance devices 322 and 324 switch between an "on" state and an "off" state during multiple switching cycles of the received time-varying magnetic field to prevent current and voltage spikes.

[0035] In many implementations, the ASK modulation impedances 322 and 324 can be capacitors affecting the capacitive load of the receiving coil 108. In some embodiments, impedances 322 and 324 can also be formed by other impedance components (i.e., inductors and resistors). Switching impedances 322 and 324 then changes the total impedance of the circuit formed by the receiving coil 108 and capacitor 330, resulting in an ASK signal that meets Qi specification requirements.

[0036] In some embodiments, the controller 302, along with the rectifier 304, rectifier control 310, DC power supply circuit 308, FSK demodulator 314, interface 316, ASK modulator 306, sensor 320, and memory 318, can be formed on a single integrated circuit chip 312. External components (such as impedances 322 and 324, capacitors 326, 328 and 338, and receiving coil 108) can be mounted on a printed circuit board (PCB) together with IC 312.

[0037] In a conventional wireless power receiver, the switching of impedances 322 and 324 by the ASK modulator 306 occurs during the switching period of the received time-varying magnetic field, resulting in current and voltage spikes in the wireless power receiver 110. These spikes can potentially damage components of the wireless power receiver 110. Furthermore, in some cases, the ASK modulator 306, cooperating with impedances 322 and 324, increases or decreases the ASK signal depth to allow detection of the ASK signal at the wireless power transmitter 102. The ASK signal depth can be adjusted due to the high signal-to-noise ratio (SNR) or saturation of the peak detector 222 and ASK decoder 210 of the wireless power transmitter 102. However, regardless of the specific circumstances, the conventional switching of impedances 322 and 324 in ASK modulation can damage the wireless power receiver 110.

[0038] Figure 4A , Figure 4B and Figure 4C The diagram illustrates the operation of ASK modulation in a conventional wireless power receiver 400. (Example) Figure 4AAs shown, IC 416 includes an ASK modulator 402 coupled to impedances 404 and 406. Impedances 404 and 406 may each include multiple capacitors, which can be switched by the ASK modulator 402 to control the signal depth. Figure 4A In the example shown, impedance 404 includes capacitors 408 and 410, each independently controlled by ASK modulator 402 to switch the capacitance to node AC1. Similarly, impedance 406 includes capacitors 412 and 414, each independently controlled by ASK modulator 402 to switch the capacitance to node AC2. Multiple capacitors are typically used to control the ASK modulation depth and are therefore switched together according to the modulation depth. Impedances 404 and 406 are turned on and off between switching cycles to change the impedance of the LC resonant circuit to achieve ASK modulation. The switching cycle here refers to the frequency of the radio power signal (i.e., the time-varying magnetic field) received at receiver coil 108. Turning impedances 404 and 406 on and off as described above changes the resonant energy storage characteristics of the LC resonant circuit formed by receiver coil 108 and capacitor 328, thereby causing a sharp change in the current in coil 108.

[0039] Figure 4B The diagram illustrates the situation when impedances 404 and 406 are turned off by ASK modulator 402. (As shown...) Figure 4B As shown, trace 420 illustrates the voltage at node AC1, while trace 422 illustrates the voltage at node AC2. As indicated, the voltages at AC1 and AC2 are driven at the frequency of the time-varying magnetic field received at receiving coil 108. Trace 424 illustrates the capacitors with turn-off impedances 404 and 406, where the inductor is floating. Trace 426 illustrates the current through the coil. As indicated, the current spikes during the periods when impedances 404 and 406 are turned off.

[0040] As shown in trace 426, spikes in the coil current may cause corresponding spikes on the LC node (the node between receiver coil 108 and capacitor 328). This is in Figure 4B The diagram shows the voltage at the LC node (trace 428). A large spike at the LC node could damage circuitry connected to this pin, which could include a magnetically safe transfer (MST) isolated MOSFET or demodulation circuitry.

[0041] Embodiments of the present invention are used to reduce or eliminate spikes resulting from switching ASK modulation. Specifically, an embodiment of the receiver 110 according to the present invention includes an ASK modulator 306, which is controlled by a controller 302 to switch between impedance on and off to extend the transition time over several cycles of the time-varying magnetic field received by the receiving coil 108. The number of cycles that can be used to turn the impedance used in the ASK modulation on or off can be four or more cycles, for example, four to eight cycles or more. In some embodiments, 10 or more cycles can be used. The number of cycles required to turn the impedance on or off is balanced with maintaining the impedance state for a longer period of time to reduce the resulting coil current spikes. Typically, the ASK modulation symbol width is about 200 μs, which may span hundreds of switching cycles of the received time-varying magnetic field. In this case, even a transition time of more than 10 switching cycles can be used. However, controlling the transition requires processing time, which can also be taken into account when determining the transition time.

[0042] Several methods can be employed to influence ASK modulation by switching ASK impedances 322 and 324 between "on" and "off" states over several switching cycles. In some embodiments, the impedances are slowly turned on by the slow conduction of a capacitor, by regulating the current to impedances 322 and 324 from low to high current. For example, the impedance of the control switch can be used as a variable current source, slowly transitioning from low to high current over several switching cycles of a time-varying magnetic field received by receiving coil 108. In some embodiments, the pulsed conduction of the capacitor across the impedance can be used to slowly increase the voltage across the capacitor in each switching cycle until full voltage is reached. This eliminates the need for multiple parallel capacitors (such as...) Figure 4A In the case of the wireless power receiver 400 shown, each of these embodiments can be used to dynamically change the modulation depth of the system. Furthermore, the control of the modulation depth allows operation within the Wireless Power Alliance (WPC), Qi standard, or Power Alliance (PMA) protocol.

[0043] In some other embodiments, the ASK modulator 306 adjusts the values ​​of impedances 322 and 324 over time to slowly (over four or more switching cycles) transition between “on” and “off” states. Specifically, impedances 322 and 324 can be complex impedances formed by an array of individual smaller impedances, each of which can be turned on or off to change the overall value of impedances 322 and 324. The complex impedances 322 and 324 can be formed by an array or combination of capacitors, resistors, and inductors, which are individually turned on or off to slowly turn on or off the total impedance load of the LC circuit formed by the series-connected receiving coil 108 and the capacitor pair 330. Thus, the transition between “on” and “off” states is achieved over multiple switching cycles of the magnetic field received by the receiving coil 108.

[0044] Figure 5A and Figure 5B An example embodiment of receiver 110 is illustrated, wherein the current to impedances 322 and 324 is controlled to transition these impedances to “on” and “off” states over multiple switching cycles. As described above, the transition between “on” and “off” over multiple switching cycles of the time-varying magnetic field received at receiver coil 108 allows for the reduction or elimination of current spikes that could damage components in the wireless power receiver 110.

[0045] Figure 5A An embodiment of a wireless power receiver 110, receiver 500, is illustrated, wherein the current to impedances 322 and 324 is controlled during ASK modulation switching. Figure 5A In the specific example shown, impedances 322 and 324 are illustrated as being formed by a single capacitor. However, impedances 322 and 324 can be formed by complex impedances using a combination of capacitors, resistors, and inductors.

[0046] exist Figure 5A In this configuration, rectifier 304 is formed by transistors 502, 504, 506, and 508. As shown, rectifier 304 includes transistors 502 and 504 connected in series between VRECT and ground (GND), wherein the node between transistors 502 and 504 is coupled to node AC1. Similarly, rectifier 304 includes transistors 506 and 508 connected in series between VRECT and ground (GND), wherein the node between transistors 506 and 508 is coupled to node AC2. The gates of transistors 502, 504, 506, and 508 are controlled by block 510, which includes... Figure 3 The rectifier control 310 shown is controlled by the controller 302.

[0047] When the ASK modulator 306 initiates an event (in this disclosure, "event" refers to when the ASK modulator 306 transitions impedances 322 and 324 between "on" and "off" states), the control circuit system 510 sets current targets for impedances 322 and 324 at nodes COM1 and COM2. As described above, in Figure 5A In the illustrated embodiment, impedances 322 and 324 are capacitors. Therefore, control 510 influences current control circuitry 512 to ramp the current at nodes COM1 and COM2 until impedances 322 and 324 have fully switched (i.e., from "on" to "off" or from "off" to "on"). Over several switching cycles, the current target will slowly increase (or decrease) until the impedances are effectively "on" or "off".

[0048] exist Figure 5A In the example embodiment shown, the current control circuit 512 includes a FET 518, which is coupled between ground and impedance 322 at node COM1. The gate of the FET 518 is controlled by an operational amplifier 514. The operational amplifier 514 receives from the controller 510 a first input indicating a current target for node COM1 and a second input indicating the current through the transistor 518. Figure 5A As shown, the current control circuit 512 also includes a FET 520, which is coupled between ground and impedance 324 at node COM2. The gate of FET 520 is controlled by operational amplifier 516. Operational amplifier 516 receives from controller 510 a first input indicating the current target for node COM2 and a second input indicating the current through FET 520. As described above, the current targets for COM1 and COM2 are achieved by operational amplifiers 514 and 516, which respectively control the operation of FETs 518 and 520. As further discussed above, controller 510 ramps or ramps the current targets up or down over several switching cycles, thereby “turning on” or “turning off” the impedance.

[0049] In some embodiments, the current control circuit 512 is controlled by the current control 510 to operate during the idle time between switching cycles. For example... Figure 5A As shown, the current controller 510 includes, as follows: Figure 3 The rectifier control 310 shown monitors and tracks the switching cycle of the time-varying magnetic field received by the receiver coil 108, thereby causing power rectification by the rectifier 304 and allowing the identification of no-load times. Embodiments of some examples may keep the current source continuously on throughout the switching cycle, provide active current control only during charging, or some combination of these alternatives.

[0050] As described above, controller 510 includes rectifier control 310 and controller 302. During each ASK modulation event, controller 302 executes instructions to switch impedances 322 and 324 to "on" or "off". Therefore, as described herein, controller 510 executes code to ramp impedances 322 and 324 over several switching cycles. Furthermore, in Figure 5A The diagram further illustrates the layout of the IC chip 312 of the wireless power transmitter 500, which identifies some pin connections (VRECT, COM1, AC1, AC2, COM2, and GND).

[0051] Figure 5B The diagram shows... Figure 5A The operation of the ASK modulator 306 shown. Figure 5B The diagram illustrates the voltage at node AC1 as the state of impedance 322 changes. The voltage at node AC2 behaves similarly to the current flowing through FET 520. The diagram also illustrates the current flowing through FET 518 at node COM1. As shown, the transition between states takes a transition time T, which spans several switching cycles (e.g., four or more) of the received magnetic field. Figure 5B The operation is further illustrated under the conditions of low current limit, medium current limit, and no current limit.

[0052] It should be noted that during the transition from the high voltage to the low voltage at node AC1, when the AC voltage drops below the voltage across the capacitor, the capacitor naturally discharges through the parasitic diode of the current source. In some embodiments, this effect does not occur, and a constant discharge current is used instead. In some embodiments, the discharge current can be synchronously turned on in a manner that minimizes system interference to precisely discharge impedances 322 and 324. Furthermore, Figure 5B The illustration shows the case of a constant current limit (i.e., the current limit is not controlled to ramp up with time).

[0053] Figure 5A and Figure 5B An embodiment of receiver 110 shown: Receiver 500, which causes the impedance of the LC network to change slowly over multiple switching cycles, thereby achieving natural, passive stabilization and preventing, etc. Figure 4A , Figure 4B and Figure 4C The ICOIL spikes in the normal case are shown in the figure.

[0054] Since the current source formed by FETs 518 and 520 is also an impedance, some embodiments can provide a more complex method that can be executed by control 510, wherein receiver 500 uses a combination of current source impedances and then jumps to full “on” when the current source at the capacitor approaches the target final impedance for a given switching transition.

[0055] In such Figure 5A In some embodiments shown, the depth of ASK modulation can be controlled by limiting the total maximum current that defines the “on” state of impedances 322 and 324. Controller 502 can then ramp the current up to the finite total maximum current to provide the “on” state and ramp the current down from the total maximum current to ramp to the “off” state.

[0056] Figure 5A The illustration specifically depicts current control 512 formed using operational amplifiers 514 and 516. However, in some embodiments, the same effect can be achieved by using current mirrors or other techniques known to those skilled in the art of semiconductor circuit design to more fully control the current through FETs 518 and 520.

[0057] Figure 6A and Figure 6B Another example embodiment of receiver 110 is illustrated, wherein the voltages to impedances 322 and 324 are controlled to switch those impedances “on” and “off” over multiple switching cycles. As described above, the switching between “on” and “off” over multiple switching cycles of the time-varying magnetic field received at receiver coil 108 allows for the reduction or elimination of current spikes that could potentially damage components in the wireless power receiver 110. Figure 6A In the example shown, as discussed in more detail below, the voltage across impedances 322 and 324 increases or decreases depending on the voltage across AC1 and AC2, so as to switch impedances 322 and 324 between “on” and “off” states over multiple switching cycles of the time-varying magnetic field.

[0058] Figure 6A An embodiment of receiver 110 is illustrated: receiver 600, wherein during ASK modulation, the voltages of impedances 322 and 324 are controlled to transition between "on" and "off". Figure 6AIn the example shown, impedances 322 and 324 are illustrated as capacitors, but impedances 322 and 324 can be complex impedances formed by a combination of capacitors, resistors, and inductors. Controller 602 includes rectifier control 310 and controller 302 to provide signals to voltage control circuitry 604. The signals provided to voltage control circuitry 604 may include pulse-width modulated (PWM) voltage signals for controlling the voltages on nodes COM1 and COM2. In some embodiments, the PWM voltage signal may be generated using a clock signal in controller 602. In some embodiments, such as Figure 6A As shown, PWM is implemented by comparing with the corresponding AC node voltage. In some embodiments, PWM is generated by a voltage threshold transition. In some embodiments, the controller 602 can provide a voltage signal that allows for pulsed voltage increases across impedances 322 and 324 when compared with the voltages at nodes AC1 and AC2.

[0059] exist Figure 6A In the example shown, voltage control circuit 604 receives signals into comparators 606 and 608. The output signals from comparators 606 and 608 drive the gates of FETs 610 and 612, respectively. FET 610 is coupled between node COM1 and ground (GND) and affects impedance 322. FET 612 is coupled between node COM2 and GND and affects impedance 324. Comparator 606 receives a voltage signal from controller 602 and compares it with the voltage at node AC1 to provide a gate voltage to FET 610. Similarly, comparator 608 receives a voltage signal from controller 602 and compares it with the voltage at node AC2 to provide a gate voltage to FET 610. Therefore, when the voltage signal is greater than AC1, node COM1 is coupled to ground; otherwise, it is disconnected from ground. Similarly, when the voltage signal is greater than AC2, node COM2 is coupled to ground; otherwise, it is disconnected from ground. In this way, as the voltage increases or decreases, the impedances 322 and 324 can increase or decrease, thus affecting the transition.

[0060] As described above, in some embodiments, the controller 602 can provide the PWM signal directly to the gates of transistors 610 and 612. In this case, comparators 606 and 608 are omitted. The PWM signal can be synchronized with the voltages on AC1 and AC2 to provide transitions in impedances 322 and 324 over several switching cycles of the time-varying magnetic field.

[0061] When an ASK modulation event starts or ends via ASK modulator 306 (impedances 322 and 324 are "on" or "off"), control circuit 602 sets thresholds to control the on and / or off states of FETs 610 and 612 to nodes COM1 and COM2. As described above, voltage targets are compared with the voltages at nodes AC1 and AC2, respectively, to adjust the voltages at nodes COM1 and COM2 over multiple switching cycles.

[0062] Controller 602 includes rectifier control 310 and controller 302. During each ASK modulation event, controller 302 executes instructions to switch impedances 322 and 324. Therefore, controller 602 executes code to ramp impedances 322 and 324, as described herein, over several switching cycles. In some embodiments, voltage control circuitry 604 is controlled by current control 602 to operate during the idle time between adjacent switching cycles. Figure 6A As shown, the current controller 602 includes, as follows: Figure 3 The rectifier control 310 shown monitors and tracks the switching cycle of the magnetic field received by the receiver coil 108, thereby causing power rectification by the rectifier 304 to allow the identification of no-load time.

[0063] In addition, Figure 6A The diagram further illustrates the layout of the IC chip 312 of the wireless power transmitter 600, which identifies some pin connections (VRECT, COM1, AC1, AC2, COM2, and GND).

[0064] In some embodiments, the on / off characteristics of impedances 322 and 324 can also be set using other techniques, such as adjustment with a fixed time delay. Figure 6A The illustrated embodiment also allows for adjustment of the modulation depth by adjusting the termination voltages at COM1 and COM2 without the need for additional capacitors.

[0065] like Figure 6B As shown in the waveform, the voltage target slowly increases (or decreases) over a period T of several switching cycles until FETs 610 and 612 are always effectively “on” (or “off”). Figure 6B The diagram illustrates the impedance transition at AC1 (322) and the operation of FET 610. Similar behavior was observed for the impedance transition at AC2 (324) and the operation of FET 612. Figure 6B The illustration shows the transitions of various threshold levels used to set voltage thresholds in controller 602, as well as the current at COM 1.

[0066] In some embodiments, the voltage circuit 604 is active only during the idle time between switching cycles. Other methods are also envisioned to maintain continuous voltage conduction. For example... Figure 6B As shown, in the falling edge case illustrated below, the capacitor discharges naturally by switching the parasitic body diode of FET 610. However, this is not necessary, as those skilled in the art will understand how the techniques used during turn-on can be equally applied to turn-off transitions.

[0067] like Figure 6B As shown, Figure 6A The receiver 600 shown causes the network impedance to change slowly over multiple switching cycles, thereby achieving natural, passive stabilization and preventing current spikes through the receiver coil 108. Figure 6A The example shown illustrates the use of comparators 606 and 608. However, the same result can be achieved by using source followers or other techniques known to those skilled in the art of semiconductor circuit design, thereby controlling the voltages at nodes AC1 and AC2 to cause the states of impedances 322 and 324 to transition slowly.

[0068] In such Figure 6A In some embodiments shown, the depth of ASK modulation can be controlled by limiting the total voltage, which defines the “on” state of impedances 322 and 324. Controller 602 can then ramp the current up to a finite total maximum current to provide the “on” state and ramp the current down from the total maximum current to ramp to the “off” state.

[0069] Figure 7A and Figure 7B An embodiment of receiver 110 is illustrated: receiver 700, wherein the impedances of impedances 322 and 324 are ramped to switch impedances 322 and 324 between "on" and "off" states. Figure 7AIn the specific example shown, impedance 322 includes N capacitors 710-1 to 710-N. Similarly, impedance 324 includes N capacitors 712-1 to 712-N. In this configuration, each of the capacitors 710-1 to 710-N and 712-1 to 712-N is arranged to be on or off such that the total impedance of impedances 322 and 324 is ramped to be fully on or fully off. Thus, when each of the capacitors 710-1 to 710-N and 712-1 to 712-N is on or off, the impedance increases or decreases to reduce spikes in the current of the emitter coil 108. In some implementations, capacitors 710-1 to 710-N and 712-1 to 712-N may be binary weighted to allow for incremental increases in the effective capacitive load. In some embodiments, the array of impedances 712-1 to 712-N may include capacitors, resistors, and inductors.

[0070] like Figure 7A As shown, controller 702 provides signals to impedance controller 704 to turn capacitors 710-1 to 710-N and 712-1 to 712-N on or off. Figure 7A As shown, impedance controller 704 includes switching networks 706 and 708. Switching network 706 may include an array of N transistors, which, according to a signal from controller 702, couple capacitors 710-1 to 710-N to ground by switching one of the N transistors in the switching network 706. Similarly, switching network 708 may include an array of N transistors, which, according to a signal from controller 702, couple capacitors 712-1 to 712-N to ground.

[0071] As described above, controller 702 includes rectifier control 310 and controller 302. During each ASK modulation event, controller 302 executes instructions to switch impedances 322 and 324 to "on" or "off". Thus, as described herein, controller 702 executes code to switch impedances 322 and 324 over multiple switching cycles. In some embodiments, impedance control circuitry 704 is controlled by controller 702 to operate as follows: switching impedances during idle time between switching cycles. Controller 702 can determine the switching idle time by monitoring rectifier control 310.

[0072] In addition, Figure 7A The diagram further illustrates the layout of the IC chip 312 of the wireless power transmitter 700, which identifies some pin connections (VRECT, AC1, AC2, and GND). Figure 7AThe illustrated embodiment may be ideal because it slowly turns on or off the impedance ramped by controller 702. In most implementations where transmitter 700 is formed on IC 312, this solution uses more IC pins and components on the PCB than found in other embodiments or more conventional receivers. Figure 7A As shown, pins COM1_1 to COM1_N are coupled to capacitors 710-1 to 710-N respectively, while pins COM2_1 to COM2_N are coupled to capacitors 712-1 to 712-N, resulting in 2N pins for communication instead of 2 or 4 pins. Furthermore, capacitors 710-1 to 710-N and 712-1 to 712-N are mounted on the PCB along with IC 312. This number of pins and the additional space on the PCB may be disadvantageous for certain applications, such as space-constrained mobile phone applications.

[0073] exist Figure 7A and Figure 7B In the embodiment of the wireless transmitter 700 shown, when an ASK modulation event begins, the control circuit 702 sets the number and sequence of communication capacitors to be turned on and / or off, and signals switches 706 and 708 to sequentially activate capacitors selected from capacitors 710-1 to 710-N and 712-1 to 712-N. As the capacitance changes, the effective capacitance impedances of impedances 322 and 324 also change. Over several switching cycles, the number of capacitors and the effective capacitance at AC nodes AC1 and AC2 can change slowly until the desired operating point is reached.

[0074] exist Figure 7B The diagram illustrates the voltage at node AC1 and the current at the communication pin (collectively referred to as COM1). It should be noted that... Figure 7B In the case of the falling edge shown, the capacitor naturally discharges through the parasitic body diode of the switching MOSFET in the switching array 706. This causes the network impedance to change slowly over multiple switching cycles, thus allowing for natural, passive stabilization and preventing ICOIL spikes. Figure 7A The illustrated embodiment can also control the modulation depth by limiting the number of capacitors that are turned on for the fully on state.

[0075] As described above, embodiments of wireless power transmitters that control the ASK modulation impedance during on and off periods limit or eliminate interference to the wireless power transmission / system. Although the examples of the above embodiments are illustrated where ASK modulation impedances 322 and 324 are implemented using capacitors, other impedances (i.e., resistors or inductors) can also be used in the ASK modulation impedances 322 and 324 implemented herein.

[0076] Figure 8 The illustration depicts a method 800 according to some embodiments. For example... Figure 8 As shown, method 800 is initiated in step 802, where ASK modulation is performed to either "turn on" or "turn off" impedances 322 and 324. In step 804, controller 302 ramps impedances 322 and 324 so that transitions occur over multiple switching cycles of the received magnetic field. In step 806, once the transition is complete (i.e., impedances 322 and 324 are fully "turned on" or "turned off"), method 800 maintains the impedance values ​​until the next ASK modulation event is initiated. As a result, as... Figure 5B , Figure 6B and Figure 7B As shown, during data transmission, the transition between high impedance and low impedance states occurs over multiple switching cycles.

[0077] In some embodiments, in step 804, the current through impedances 322 and 324 is limited to reduce the effective impedance of impedances 322 and 324. Figure 5A and Figure 5B The embodiment is illustrated in detail below. In some embodiments, the method can be used to control the modulation depth by limiting the conduction values ​​of impedances 322 and 324.

[0078] In some embodiments, in step 804, the voltage across impedances 322 and 324 is limited to reduce the effective impedances 322 and 324. Figure 6A and Figure 6B An example of this embodiment is illustrated. In some embodiments, impedances 322 and 324 are controlled using a PWM provided by the system. In some embodiments, the PWM signal is generated by a clock. In some embodiments, the PWM signal is generated by a voltage threshold transition. In some embodiments, the voltage threshold is compared with the voltage of the corresponding AC node to control the voltage to impedances 322 and 324. In some embodiments, the modulation depth can be controlled by limiting the conduction values ​​of impedances 322 and 324.

[0079] In some embodiments, in step 804, ASK modulation impedances 322 and 324 each include a plurality of individual impedances, which are switched to tilt the total impedances 322 and 324 to an "on" or "off" state. The plurality of individual impedances can be sequentially turned on or off to manage the impedance values ​​of impedances 322 and 324. In some embodiments, the plurality of individual impedances may have binary weighting.

[0080] The above detailed description is provided to illustrate specific embodiments of the invention and is not intended to be limiting. Many variations and modifications are possible within the scope of the invention. The invention is set forth in the appended claims.

Claims

1. A method for performing amplitude shift keying (ASK) modulation in a wireless power receiver, comprising: Initiating a transition of the ASK impedance from a first state to a second state, the ASK impedance being coupled to a resonant circuit, the resonant circuit including a wireless power receiving coil that receives a time-varying magnetic field; The ASK impedance is transitioned from the first state to the second state according to the transitions over multiple switching cycles of the time-varying magnetic field. as well as Maintain the second state. The ASK impedance is formed by a plurality of impedances, and the ASK impedance ramping includes controlling which of the plurality of impedances is joined in the ASK impedance.

2. The method according to claim 1, wherein the first state is an "off" state and the second state is an "on" state.

3. The method according to claim 1, wherein the first state is an "on" state and the second state is an "off" state.

4. The method of claim 1, wherein causing the ASK impedance transition comprises: The current is controlled to the ASK impedance.

5. The method of claim 1, wherein causing the ASK impedance transition comprises: The voltage across the ASK impedance is controlled by pulsed voltage.

6. The method of claim 5, wherein pulsing the voltage across the ASK impedance comprises: A pulse width modulation (PWM) signal is applied to control the voltage.

7. The method of claim 5, wherein pulsing the voltage across the ASK impedance comprises: The received power supply voltage is compared with the target voltage.

8. The method of claim 1, further comprising: The depth of the ASK modulation is controlled by controlling the maximum impedance.

9. The method of claim 4, wherein the maximum current is set to control the ASK modulation depth.

10. The method of claim 5, wherein the maximum voltage is set to control the ASK modulation depth.

11. The method of claim 1, wherein the maximum number of the plurality of impedances is determined to control the ASK modulation depth.

12. The method of claim 1, wherein the impedances of the plurality of impedances are binary weighted.

13. The method of claim 1, wherein causing the ASK impedance transition comprises: During the idle time of the switching cycle, the ASK impedance is adjusted.

14. A wireless power receiver with ASK modulation, comprising: A rectifier is coupled to receive wireless power from a resonant circuit that includes a receiver coil; An impedance control circuit is coupled to an ASK impedance, the impedance control circuit being coupled to affect the impedance of the resonant circuit, wherein the ASK impedance is formed by a plurality of impedances, and wherein the impedance control circuit controls which of the plurality of impedances are joined to the ASK impedance. as well as The controller is coupled to the rectifier and the impedance control circuit. The controller executes instructions to Initiate the transition of the ASK impedance from the first state to the second state; The ASK impedance is transitioned from the first state to the second state based on the transitions during multiple switching cycles of the time-varying magnetic field received by the resonant circuit; and Maintain the second state.

15. The wireless power receiver of claim 14, wherein the first state is an "off" state and the second state is an "on" state.

16. The wireless power receiver of claim 14, wherein the first state is an "on" state and the second state is an "off" state.

17. The wireless power receiver of claim 14, wherein the impedance control circuit controls the current to the ASK impedance.

18. The wireless power receiver of claim 14, wherein the impedance control circuit controls the voltage to the ASK impedance by pulsed voltage across the ASK impedance.

19. The wireless power receiver of claim 18, wherein pulsed voltage comprises applying a pulse width modulation (PWM) signal that controls the voltage.

20. The wireless power receiver of claim 18, wherein pulsing the voltage across the ASK impedance comprises: The received power voltage is compared with the target voltage.

21. The wireless power receiver of claim 14, wherein the impedances of the plurality of impedances are binary weighted.

22. The wireless power receiver of claim 14, further comprising: The depth of the ASK modulation is controlled by controlling the maximum impedance.

23. The wireless power receiver of claim 22, wherein the impedances of the plurality of impedances are binary weighted.

24. The wireless power receiver of claim 14, wherein ramping the ASK impedance comprises: The ASK impedance is adjusted during the idle time of the switching cycle.

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