A wireless charging circuit, device, and system

Abstract

Embodiments of the present application disclose a wireless charging circuit, device and system. The circuit comprises a phase shifter configured to perform phase processing on an input signal; a driving amplifier configured to amplify the phase-processed input signal; a power control unit configured to output a control signal, wherein the control signal comprises transmission power control information of a charging signal; and a power amplification unit having an input end, an output end and a first control end, wherein the input end is connected to the driving amplifier, the output end is connected to a transmission antenna, and the first control end is connected to the power control unit to receive the control signal and perform power amplification on the amplified input signal of the driving amplifier according to the power control information in the control signal, so as to obtain the charging signal and transmit the charging signal through the transmission antenna, wherein the power control information is used to control the transmission power of the charging signal to be located in a saturation region of the output power of the power amplification unit.

Description

Technical Field

[0001] This application relates to the field of wireless power transmission, and more particularly to a wireless charging circuit, device, and system. Background Technology

[0002] Wireless charging technology is now widely used in products such as mobile phones, watches, fitness trackers, Bluetooth headsets, and even electric vehicles. Wireless charging technology can be divided into two types: low-power wireless charging and high-power wireless charging. Low-power wireless charging often uses electromagnetic induction, such as for charging mobile phones; high-power wireless charging often uses resonant current, such as for charging electric vehicles. Because the charger and the device communicate via magnetic field, there is no need for a wired connection, making charging more convenient and allowing for more aesthetically pleasing designs.

[0003] Given the convenience of wireless charging and the widespread use of smart devices, controlling the power consumption of wireless charging devices while providing charging signals is an urgent problem to be solved. Summary of the Invention

[0004] To address any of the aforementioned technical problems, embodiments of this application provide a wireless charging circuit, device, and system.

[0005] To achieve the objectives of the embodiments of this application, the embodiments of this application provide a wireless charging circuit, including:

[0006] A phase shifter is used to process the phase of an input signal.

[0007] A driver amplifier, connected to the phase shifter, is used to amplify the phase-processed input signal;

[0008] A power control unit is used to output control signals, wherein the control signals include transmission power control information of the charging signal;

[0009] A power amplifier unit has an input terminal, an output terminal, and a first control terminal. The input terminal is connected to the driver amplifier, the output terminal is connected to the transmitting antenna, and the first control terminal is connected to the power control unit. The first control terminal is used to receive the control signal, amplify the input signal amplified by the driver amplifier according to the power control information in the control signal, obtain the charging signal, and transmit it through the transmitting antenna. The power control information is used to control the transmission power of the charging signal to be within the saturation region of the output power of the power amplifier unit.

[0010] A wireless charging device, comprising:

[0011] A signal generator is used to generate input signals;

[0012] At least two of the above circuits, each of which is connected to the signal generator;

[0013] The antenna assembly is connected to the at least two circuits.

[0014] A wireless charging system includes a device to be charged and the wireless charging device described above.

[0015] One of the above technical solutions has the following advantages or beneficial effects:

[0016] The power amplification unit amplifies the input signal amplified by the driver amplifier according to the power control information in the control signal to obtain the charging signal, so that the transmission power of the charging signal is located in the saturation region of the output power of the power amplification unit, thereby improving the energy efficiency of the power amplification unit and reducing the power consumption of the wireless charging device.

[0017] Other features and advantages of the embodiments of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the embodiments of this application. The objects and other advantages of the embodiments of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0018] The accompanying drawings are used to provide a further understanding of the technical solutions of the embodiments of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the embodiments of this application and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0019] Figure 1(a) is a schematic diagram of the beacon signal path;

[0020] Figure 1(b) is a schematic diagram of the charging signal path;

[0021] Figure 2 This is a schematic diagram of the wireless charging circuit 20 in the WTP Source.

[0022] Figure 3 This is a schematic diagram of the output power curve and energy efficiency curve of an RFPA.

[0023] Figure 4 A schematic diagram of the wireless charging circuit 20 provided in an embodiment of this application;

[0024] Figure 5 for Figure 4 Another schematic diagram of the circuit shown;

[0025] Figure 6 Gain curve of the gain-adjustable RFPA24' provided for embodiments of this application;

[0026] Figure 7 for Figure 4 Another schematic diagram of the circuit shown;

[0027] Figure 8 for Figure 7 Another schematic diagram of the circuit shown;

[0028] Figure 9 for Figure 8 Another schematic diagram of the circuit shown;

[0029] Figure 10 This is a schematic diagram illustrating the application of the wireless charging circuit 20 provided in the embodiments of this application;

[0030] Figure 11 A schematic diagram of the wireless charging device 100 provided in an embodiment of this application;

[0031] Figure 12 This is a schematic diagram of a wireless charging system provided in an embodiment of this application. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0033] Wireless Power Transfer (WPT) converts radio frequency power into direct current through a rectifier, which is then used to charge batteries or directly power components of electronic devices.

[0034] The WPT system includes: a WPT source, which acts as a power provider to supply radio frequency power; and a WPT client, which acts as a power receiver to receive radio frequency power.

[0035] The WPT Client has a built-in antenna for charging. It transmits beacon signals omnidirectionally through the antenna. A portion of the signal reaches the WPT Source after direct transmission or reflection. The signal path is shown in Figure 1(a).

[0036] The WPT Source adjusts its charging signal transmission parameters according to the received beacon signal, ensuring that the charging signal transmitted by the WPT Source is sent in reverse along the path of the WPT Client's transmission signal, as shown in Figure 1(b). Because the energy of the WPT Source's transmitted signal is focused at the WPT Client's antenna after direct / reflection, the transmitted energy is concentrated at the WPT Client. The higher the energy concentration at the WPT Client's antenna, the higher the transmission efficiency of the WPT Source.

[0037] Since the parameters of the WPT Source's transmitted signal are partly derived from the beacon signal of the WPT Client, they will change as the characteristics of the received beacon signal change. For example, if the WPT Client moves, the WPT Source will update the parameters of the transmitted signal so that the charging signal of the WPT Source is refocused at the new position of the WPT Client.

[0038] The WTP Source can be equipped with multiple wireless charging circuits to transmit and receive signals. Each wireless charging circuit can have the same structure and be deployed in an array on the WTP Source, such as a 3*3 array, a 4*4 array, an 8*8 array, etc.

[0039] Figure 2 This is a schematic diagram of the wireless charging circuit 20 in the WTP Source. Figure 2 As shown, one end of the wireless charging circuit 20 is connected to the signal generator 10, and the other end is connected to the antenna 30; wherein:

[0040] Signal generator 10 is used to generate sinusoidal signals;

[0041] The wireless charging circuit 20 is used to process the generated sinusoidal signal to obtain a charging signal and transmit it through the antenna 30; and to receive beacon signals through the antenna 30 and use the beacon signals to adjust the operating parameters of the modules in the wireless charging circuit 20.

[0042] Furthermore, the wireless charging circuit 20 includes the following modules:

[0043] Phase shifter 21 is used to perform phase shifting processing on the input signal;

[0044] The driver amplifier 22 is used to amplify the phase-shifted input signal to an appropriate strength to meet the requirements of the next stage signal;

[0045] The adjustable attenuator 23 is used to attenuate the signal processed by the driver amplifier 22.

[0046] The radio frequency power amplifier (RFPA)24 is used to amplify the attenuated signal to the required level by the system.

[0047] Switching device 28 is used to realize a shared antenna for transmitting and receiving signals;

[0048] Power divider 27 is used to split the received beacon signal into two equal paths;

[0049] Amplitude / phase extractor 26 is used to extract the phase and amplitude information of the input signal;

[0050] The signal processor 25 is used to output control signals based on amplitude and phase information to control the processing of input signals.

[0051] The following is about Figure 2 The processing method for the structure shown is explained below:

[0052] Step 101: When receiving the Beacon signal sent by the WPT Client, the switching device 28 controls the power divider 27 and the antenna 30 to be in the conducting state.

[0053] Step 102: The power divider 27 sends the received signal to the amplitude / phase extractor 26;

[0054] Step 103: Amplitude / phase extractor 26 extracts the amplitude and phase information of the Beacon signal and outputs it to signal processor 25;

[0055] Step 104: The signal processor 25 outputs a corresponding control signal based on the received amplitude and phase signals;

[0056] Step 105: Signal processor 25 controls the working state of various modules: controls the phase shift of phase shifter 21, controls the power amplification of drive amplifier 22, controls adjustable attenuator 23 to work in a suitable attenuation state, and controls RFPA24 to amplify the input signal.

[0057] Step 106: When the WPT Source needs to transmit a signal, the switching device 28 controls the RFPA24 and the antenna 30 to be in the conducting state;

[0058] Step 107: Phase shifter 21 receives input signal from signal generator 10, and performs phase shifting processing on input signal according to control signal issued by signal processor 25, outputting phase-shifted signal;

[0059] Step 108: Drive amplifier 22 amplifies the magnitude of the phase-shifted signal according to the control signal requirements of signal processor 25;

[0060] Step 109: The adjustable attenuator 23 adjusts the attenuation value according to the control signal of the signal processor 25 to attenuate the signal processed by the drive amplifier 22.

[0061] Step 110: RFPA24 amplifies the signal processed by the adjustable attenuator 23 according to the control signal of the signal processor 25 to obtain a charging signal, which is then transmitted to the antenna 30 through the switching device 28 and emitted by the antenna 30.

[0062] In the above process, the WTP Source adjusts the strength of the charging signal by adjusting the input power of the RFPA24, which in turn is controlled by adjusting the attenuation value of the variable attenuator. Since the RFPA24 is a linear power amplifier (PA), its gain is fixed. Therefore, the higher the output power of the RFPA24, the higher its energy utilization rate; conversely, the lower the output power, the lower its energy utilization rate.

[0063] Figure 3 This is a schematic diagram of the output power curve and energy efficiency curve of an RFPA. Figure 3 As shown, Pout is the output power curve, and PAE is the energy efficiency curve. From Figure 3 It can be seen that the output power Pout is directly proportional to the input power Pin. The RFPA has its maximum energy efficiency at an input power of 40 dBm, approximately 60%; however, when operating at lower power levels (e.g., 20 dBm), the RFPA's energy efficiency is much lower, only about 5%.

[0064] Since lower energy efficiency means more energy is wasted, from Figure 3 As shown in the PAE curve, within the input power range of 10dBm to 40dBm, energy consumption exceeds 50% only when the input power is between 36dBm and 40dBm. The energy efficiency corresponding to other input power values ​​is relatively low, indicating a serious energy waste.

[0065] Based on the above-mentioned technical problems, the embodiments of this application provide the following solutions:

[0066] Figure 4 This is a schematic diagram of the wireless charging circuit 20 provided in an embodiment of this application. Figure 4 As shown, the wireless charging circuit includes a phase shifter 21, a drive amplifier 22, a power control unit 41, and a power amplifier unit 42, wherein:

[0067] Phase shifter 21 is used to perform phase processing on the input signal;

[0068] A driver amplifier 22, connected to the phase shifter, is used to amplify the phase-processed input signal;

[0069] The working principle of the phase shifter 21 and the drive amplifier is the same as that of the prior art, and will not be described again here.

[0070] The power control unit 41 is used to output a control signal, wherein the control signal includes transmission power control information of the charging signal;

[0071] The power amplifier unit 42 has an input terminal, an output terminal, and a first control terminal; wherein:

[0072] The input terminal is connected to the driver amplifier 22 and is used to receive the input signal amplified by the driver amplifier 22.

[0073] The output terminal is connected to the transmitting antenna 31 and is used to output a charging signal so that the charging signal can be transmitted through the transmitting antenna 31.

[0074] The first control terminal is connected to the power control unit 41 and is used to receive the control signal;

[0075] Specifically, the power amplification unit 42 amplifies the input signal amplified by the drive amplifier 22 according to the power control information in the control signal to obtain the charging signal, and transmits it through the transmitting antenna 31. The power control information is used to control the transmission power of the charging signal to be in the saturation region of the output power of the power amplification unit 42.

[0076] Since the power of the charging signal output by the power amplifier unit 42 is always in the saturation region of the output power of the power amplifier unit 42, the power amplifier unit 42 has high energy efficiency.

[0077] and Figure 3 Compared to the energy efficiency shown, when the input power is low, the corresponding output power is not in the saturation region of the output power. In the circuit provided in this application embodiment, the transmission power of the charging signal is always in the saturation region of the output power of the power amplifier unit 42. Therefore, the energy efficiency of the power amplifier unit 42 is improved.

[0078] Figure 5 for Figure 4 Another schematic diagram of the circuit shown. (See...) Figure 5 As shown, the circuit further includes:

[0079] The power supply control unit 43 is connected to the power amplifier unit 42 and is used to adjust the power supply voltage of the power amplifier unit according to the transmission power of the charging signal.

[0080] The supply voltage increases as the output power of the power amplifier unit 42 increases, and decreases as the output power of the power amplifier unit 42 decreases.

[0081] By utilizing a variable supply voltage, the power consumption of the power amplifier unit 42 is further reduced, thereby improving energy efficiency and effectively controlling the power consumption of the wireless charging device.

[0082] In one exemplary embodiment, the power amplification unit 42 is a gain-adjustable RFPA 24';

[0083] The power control information is the current gain value of RFPA 24'.

[0084] and Figure 2 The connection method of the RFPA24 shown is different in that one end of the RFPA24' is connected to the drive amplifier 22, and the other end is connected to the transmitting antenna 31; and, compared with Figure 2 Unlike the fixed gain of RFPA 24', the gain of RFPA 24' is adjustable. By receiving a control signal, RFPA 24' determines the required gain based on the power control information in the control signal, and amplifies the signal output by the driver amplifier 22 according to the required gain. There is no need to use the adjustable attenuator 23 to control the power value of the input signal entering RFPA 24', so that RFPA 24' can be directly connected to the driver amplifier 22.

[0085] The circuit provided in this application embodiment amplifies the signal output by the driver amplifier using an adjustable-gain RFPA24' to obtain a charging signal. This allows the adjustable-gain RFPA24' to amplify the signal output by the driver amplifier 22 according to the required gain, eliminating the need to use an adjustable attenuator 23 to control the power value of the input signal entering the adjustable-gain RFPA24'. As a result, the RFPA24' can be directly connected to the driver amplifier 22 without the need for an adjustable attenuator 23, reducing the total number of components in the circuit and facilitating circuit design and integration.

[0086] In one exemplary embodiment, the current gain value of RFPA24' is determined based on the current input power of RFPA24'.

[0087] The gain curve of the gain-adjustable RFPA24' provided in this application embodiment is as follows: Figure 6 As shown, when the input power of RFPA24' is less than a preset threshold, the current gain value of RFPA24' increases with the increase of input power; when the input power of RFPA is greater than or equal to the threshold, the current gain value of RFPA decreases with the increase of input power.

[0088] exist Figure 6 In the gain curve shown, the threshold value is approximately 36 dBm.

[0089] Figure 7 for Figure 4 Another schematic diagram of the circuit shown. (See diagram below.) Figure 7 As shown, the power control unit 41 includes an amplitude extraction unit 411 and a processing unit 412; wherein:

[0090] The amplitude extraction unit 411 is connected to the receiving antenna 32 and is used to receive beacon signals from the receiving antenna 32 and determine amplitude information based on the beacon signals.

[0091] Specifically, the amplitude extraction unit 411 may further include a power divider and a phase / amplitude extractor; wherein the functions of the power divider and the phase / amplitude extractor are the same as those of the phase / amplitude extractor. Figure 2 The structures shown have the same function, so they will not be described again here.

[0092] The beacon signal is a signal sent by the device to be charged, used to instruct the wireless charging device to adjust the transmission power of the charging signal.

[0093] The processing unit 412 is connected to the amplitude extraction unit 411 and is used to output the control signal according to the amplitude information.

[0094] Specifically, the processing unit 312 determines the target transmission power to be adjusted based on the amplitude information, determines the gain value corresponding to the target transmission power based on the target transmission power, and sends the gain value through a control signal.

[0095] Figure 8 for Figure 7 Another schematic diagram of the circuit shown. (See...) Figure 8 As shown, the transmitting antenna 31 and the receiving antenna 32 are the same antenna 30, so that the power control unit 41 and the power amplifier unit 42 share the same antenna for signal transmission, thereby improving the integration of the circuit.

[0096] Figure 9 for Figure 8 Another schematic diagram of the circuit shown. (See...) Figure 9 As shown, the circuit further includes:

[0097] The switching device 28 has two first terminals and one second terminal; one first terminal is connected to the power amplification unit 42, the other first terminal is connected to the amplitude extraction unit 411, and the second terminal is connected to the antenna 30, for controlling either the first terminal and the second terminal to be in a conducting state.

[0098] Specifically, when the first and second terminals are in a conducting state, the power amplifier unit transmits a charging signal through the antenna 30; when the other first and second terminals are in a conducting state, the amplitude extraction unit 411 receives a Beacon signal through the antenna 30 in order to adjust the current gain value of the power amplifier unit 42.

[0099] Furthermore, the conduction state of the switching device 28 can be controlled externally.

[0100] Specifically, the switching device 28 has a second control terminal, wherein the second control terminal is used to receive a conduction signal, wherein the conduction signal is used to control either the first terminal and the second terminal to be in a conduction state.

[0101] The conduction signal can be output by the processing unit 412.

[0102] Figure 10 This is a schematic diagram illustrating the application of the wireless charging circuit 20 provided in an embodiment of this application. For example... Figure 10 As shown, the wireless charging circuit 20 includes:

[0103] Power divider 27 is used to split the received beacon signal into two equal paths;

[0104] Amplitude / phase extractor 26 integrates amplitude extraction unit 411, which is used to extract the phase information and amplitude information of the input signal;

[0105] The signal processor 25 integrates a processing unit 412, which outputs a control signal based on amplitude and phase information to control the processing of the input signal. The processing operation of the input signal includes setting the current gain value of the control gain adjustable RFPA.

[0106] Switching device 28 is used to realize a shared antenna for transmitting and receiving signals;

[0107] Phase shifter 21 is used to perform phase shifting processing on the input signal;

[0108] The driver amplifier 22 is used to amplify the phase-shifted input signal to an appropriate strength to meet the requirements of the next stage signal;

[0109] The gain-adjustable RFPA 24' is used to perform amplification operations according to the gain value set by the signal processor 25.

[0110] exist Figure 10 In the structure shown, the processing flow of the wireless charging circuit is as follows:

[0111] Step 201: When receiving the Beacon signal from the WPT Client, the switching device 28 controls the power divider 27 and the antenna 30 to be in the conducting state.

[0112] Step 202: The power divider 27 sends the Beacon signal received from the antenna 30 to the amplitude / phase extractor 26;

[0113] Step 203: Amplitude / phase extractor 26 extracts the amplitude and phase information of the Beacon signal and outputs it to signal processor 25;

[0114] Step 204: The signal processor 25 outputs corresponding control signals based on the received amplitude and phase signals, including: controlling the phase shift of the phase shifter, controlling the power amplification of the drive amplifier, and controlling the adjustable gain RFPA24' to adjust the input signal to an appropriate size as required.

[0115] Step 205: Phase shifter 21 receives the input signal from signal generator 10 and performs phase shifting processing on the input signal according to the control signal issued by signal processor 25, and outputs the phase-shifted signal.

[0116] Step 206: Drive amplifier 22 amplifies the magnitude of the phase-shifted signal according to the control signal requirements of signal processor 25;

[0117] Step 207: The gain-adjustable RFPA24' amplifies the signal processed by the drive amplifier 22 according to the current gain value in the control signal of the signal processor 25 to obtain a charging signal, which is then transmitted to the antenna 30 through the switching device 28 and emitted by the antenna 30.

[0118] In the above process, the gain-adjustable RFPA24' amplifies the input signal amplified by the drive amplifier 22 according to the power control information in the control signal to obtain the charging signal, which is then transmitted through the antenna 30. The power control information is used to control the transmission power of the charging signal to be within the saturation region of the power amplifier unit's output power. Because the transmission power of the charging signal output by the power amplifier unit is always within the saturation region of the power amplifier unit's output power, the power amplifier unit has high energy efficiency. Figure 3 Compared to the energy efficiency shown, where the corresponding output power is not in the saturation region when the input power is low, the transmission power of the charging signal in the circuit provided in this application embodiment is always in the saturation region of the output power of the power amplifier unit. Therefore, the energy efficiency of the power amplifier unit is improved.

[0119] In addition, the signal output by the driver amplifier is amplified by the gain-adjustable RFPA24' to obtain a charging signal, so that the gain-adjustable RFPA24' can amplify the signal output by the driver amplifier 22 according to the required gain. There is no need to use the adjustable attenuator 23 to control the power value of the input signal entering the gain-adjustable RFPA24'. Thus, the gain-adjustable RFPA24' can be directly connected to the driver amplifier 22 without the need for the adjustable attenuator 23, reducing the total number of components in the circuit and facilitating circuit design and integration.

[0120] Figure 11 This is a schematic diagram of a wireless charging device 100 provided in an embodiment of this application. Figure 11 As shown, the wireless charging device 100 includes:

[0121] Signal generator 10 is used to generate input signals;

[0122] At least two circuits 20 as described in any one of claims 1 to 8, wherein each circuit is connected to the signal generator;

[0123] An antenna assembly, connected to the at least two circuits, includes one or more antennas 30.

[0124] Figure 12 This is a schematic diagram of a wireless charging system provided in an embodiment of this application. Figure 12 As shown, the system includes the wireless charging device 100 described above and the device to be charged 200. Wherein:

[0125] The wireless charging device 100 is used to convert current into a charging signal and output it in the form of a radio frequency signal; and to receive beacon signals emitted omnidirectionally by the device to be charged and process the beacon signals.

[0126] The device to be charged 200 is used to convert the charging signal received by the antenna into a direct current; and to use the current charging antenna to transmit a beacon signal omnidirectionally to instruct the wireless charging device 100 to adjust the transmission power of the charging signal.

[0127] It will be understood by those skilled in the art that all or some of the steps, systems, or apparatuses disclosed above, and their functional modules / units, can be implemented as software, firmware, hardware, or suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned above does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit (ASIC). Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

Claims

1. A wireless charging circuit, characterized in that, include: A phase shifter is used to process the phase of an input signal. A driver amplifier, connected to the phase shifter, is used to amplify the phase-processed input signal; A power control unit is used to output control signals, wherein the control signals include transmission power control information of the charging signal; A power amplifier unit has an input terminal, an output terminal, and a first control terminal. The input terminal is connected to the driver amplifier, the output terminal is connected to the transmitting antenna, and the first control terminal is connected to the power control unit. The power amplifier unit is a gain-adjustable radio frequency power amplifier. The gain-adjustable radio frequency power amplifier receives the control signal, determines the required gain based on power control information in the control signal, amplifies the input signal amplified by the driver amplifier according to the required gain, obtains the charging signal, and transmits it through the transmitting antenna. The power control information is used to control the transmission power of the charging signal to be within the saturation region of the output power of the power amplifier unit. A power supply control unit, connected to the power amplification unit, is used to adjust the power supply voltage of the power amplification unit according to the transmission power of the charging signal; wherein the power supply voltage increases as the output power of the power amplification unit increases and decreases as the output power of the power amplification unit decreases.

2. The circuit according to claim 1, characterized in that, The current gain value of the RF power amplifier is determined based on the current input power of the RF power amplifier; Specifically, when the input power of the RF power amplifier is less than a preset threshold, the current gain value of the RF power amplifier increases as the input power increases; when the input power of the RF power amplifier is greater than or equal to the threshold, the current gain value of the RF power amplifier decreases as the input power increases.

3. The circuit according to claim 1, characterized in that, The power control unit includes: An amplitude extraction unit, connected to a receiving antenna, is used to receive a beacon signal from the receiving antenna and determine amplitude information based on the beacon signal. The processing unit, connected to the amplitude extraction unit, is used to output the control signal based on the amplitude information.

4. The circuit according to claim 3, characterized in that, The transmitting antenna and the receiving antenna are the same antenna.

5. The circuit according to claim 4, characterized in that, The circuit also includes: A switching device having two first terminals and one second terminal; wherein one first terminal is connected to the power amplification unit, the other first terminal is connected to the amplitude extraction unit, and the second terminal is connected to the antenna, for controlling either the first terminal and the second terminal to be in a conducting state.

6. The circuit according to claim 5, characterized in that, The switching device further includes: The second control terminal is used to receive a conduction signal, wherein the conduction signal is used to control either the first terminal and the second terminal to be in a conduction state.

7. A wireless charging device, characterized in that, include: A signal generator is used to generate input signals; At least two circuits as described in any one of claims 1 to 6, wherein each circuit is connected to the signal generator; The antenna assembly is connected to the at least two circuits.

8. A wireless charging system, characterized in that, It includes the device to be charged and the wireless charging device as described in claim 7.

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