Radio frequency energy acquisition circuit capable of adaptively shunting input power

Abstract

The invention relates to a radio frequency energy acquisition circuit with input power self-adaptive shunting. The radio frequency energy acquisition circuit comprises an electromagnetic wave receiving module, a self-adaptive impedance matching module, a rectification module, a maximum power point tracking module and an energy storage module which are connected in sequence, the electromagnetic wave receiving module is used for receiving a radio frequency signal and converting the radio frequency signal into a first input power signal or a second input power signal; the adaptive impedance matching module is used for adaptively matching impedance according to the received first input power signal or the second input power signal so as to obtain a first output power signal or a second output power signal; the rectification module is used for converting the received first output power signal or the received second output power signal based on the resistance value adjusted in real time to obtain a first direct current signal or a second direct current signal; and the DC signal obtained by conversion is stored in the energy storage module through the maximum power point tracking module. The method can effectively improve the conversion efficiency and meet the requirements of equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supply circuits, and in particular relates to a radio frequency energy acquisition circuit with adaptive input power shunting. Background Art

[0002] For devices that cannot access traditional power sources, such as remote sensors, implantable wearable devices, smart home devices, and industrial monitoring sensors, frequent battery replacement not only increases maintenance costs, but may also affect the reliability and service life of the equipment. By setting up RF energy acquisition circuits in these devices, the principle of electromagnetic induction can be used to receive electromagnetic waves from the transmitter through the receiving coil, and then convert them into electrical energy to provide power for devices that cannot access traditional power sources, which can greatly improve the autonomy and sustainability of the equipment.

[0003] However, existing RF energy harvesting circuits have low conversion efficiency and cannot meet device requirements. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a radio frequency energy acquisition circuit with input power adaptive shunting. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] The present invention provides a radio frequency energy acquisition circuit with input power adaptive shunting, comprising: an electromagnetic wave receiving module, an adaptive impedance matching module, a rectifier module, a maximum power point tracking module and an energy storage module connected in sequence; the electromagnetic wave receiving module is used to receive a radio frequency signal and convert the radio frequency signal into a first input power signal or a second input power signal, wherein the power value of the first input power signal is less than the power value of the second input power signal; the adaptive impedance matching module is used to adaptively adjust the resistance between the output end of the electromagnetic wave receiving module and the input end of the rectifier module according to the received first input power signal or the second input power signal, so as to obtain the corresponding first output power signal or the second output power signal; the rectifier module is used to convert the received first output power signal or the second output power signal based on the resistance adjusted in real time by the maximum power point tracking module, so as to obtain a first direct current signal or a second direct current signal; the maximum power point tracking module is also used to generate a third direct current signal or a fourth direct current signal by using the first direct current signal or the second direct current signal; the energy storage module is used to store the third direct current signal or the fourth direct current signal, and to supply power to an external device.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] In view of the problem that the existing RF energy acquisition circuit has low conversion efficiency and cannot meet the needs of equipment, the present invention provides a RF energy acquisition circuit with adaptive input power shunting. The device acquires RF signals with a wide power range through an electromagnetic wave receiving module to reduce energy loss, and converts the RF signal into a first input power signal or a second input power signal according to the power value, and then uses an adaptive impedance matching module to automatically select a power flow path to adaptively adjust impedance matching to reduce signal transmission loss, and uses a rectifier module for conversion to obtain a first DC signal or a second DC signal, wherein the maximum power point tracking module adjusts the resistance of the rectifier module in real time, and uses the first DC signal or the second DC signal to obtain a third DC signal or a fourth DC signal, and completes wireless charging by storing the third DC signal or the fourth DC signal in an energy storage module. The RF energy acquisition circuit with adaptive input power shunting provided by the present invention can effectively improve conversion efficiency, reduce signal transmission loss, achieve RF signal acquisition with a wide power range, and meet equipment needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a structural block diagram of a radio frequency energy acquisition circuit with input power adaptive shunting provided by an embodiment of the present invention;

[0009] Figure 2 is a circuit connection diagram of an adaptive impedance matching module provided in an embodiment of the present invention;

[0010] Figure 3 is a circuit connection diagram of a first rectifier module provided in an embodiment of the present invention;

[0011] Figure 4 is a circuit connection diagram of a second rectifier module provided in an embodiment of the present invention;

[0012] Figure 5 is a schematic diagram of the structural connection of a maximum power point tracking module provided by an embodiment of the present invention;

[0013] Figure 6 Schematic diagram of the structural connection of an open-loop Buck-Boost submodule provided in an embodiment of the present invention;

[0014] Figure 7 is a simulation example diagram of a radio frequency energy harvesting circuit for adaptively splitting input power provided by an embodiment of the present invention;

[0015] Figure 8 This is an example diagram of simulation results of a radio frequency energy acquisition circuit for adaptively splitting input power provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0017] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0018] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0019] Now, in conjunction with the accompanying drawings, the RF energy harvesting circuit with input power adaptive diversion proposed by the present invention is described in detail.

[0020] Figure 1 1 is a structural block diagram of a radio frequency energy acquisition circuit with input power adaptive diversion provided by an embodiment of the present invention. Figure 1 As shown, the device includes: an electromagnetic wave receiving module, an adaptive impedance matching module, a rectifier module, a maximum power point tracking module and an energy storage module connected in sequence; the electromagnetic wave receiving module is used to receive a radio frequency signal and convert the radio frequency signal into a first input power signal or a second input power signal, wherein the power value of the first input power signal is less than the power value of the second input power signal; the adaptive impedance matching module is used to adaptively adjust the resistance between the output end of the electromagnetic wave receiving module and the input end of the rectifier module according to the received first input power signal or the second input power signal to obtain the corresponding first output power signal or the second output power signal; the rectifier module is used to convert the received first output power signal or the second output power signal based on the resistance adjusted in real time by the maximum power point tracking module to obtain a first DC signal or a second DC signal; the maximum power point tracking module is also used to generate a third DC signal or a fourth DC signal using the first DC signal or the second DC signal; the energy storage module is used to store the third DC signal or the fourth DC signal and supply power to an external device.

[0021] Here, the first input power signal is a low power signal, and the second input power signal is a high power signal, wherein the first input power signal and the second input power signal are high frequency AC signals. The electromagnetic wave receiving module is an antenna; the antenna is connected to the adaptive impedance matching module, and can convert radio frequency signals of different power ranges to widen the input power range of the radio frequency signal. Specifically, the antenna can acquire radio frequency signals with a wide input power range of 915 MHz in the environment, and convert the acquired radio frequency signals into input power signals, and compare the input power signals with the preset value to divide them into the first input power signal or the second input power signal.

[0022] Figure 2 FIG. 1 is a schematic diagram of a circuit connection of an adaptive impedance matching module provided in an embodiment of the present invention. Figure 2 As shown, the adaptive impedance matching module includes: an inductor L1, an inductor L2 and a capacitor C1; the first end of the inductor L1 is connected to the output end of the electromagnetic wave receiving module, and the second end is respectively connected to the first end of the inductor L2, the first end of the capacitor C1 and the input end of the first rectifier module, the second end of the capacitor C1 is grounded, and the second end of the inductor L2 is connected to the input end of the second rectifier module.

[0023] It should be noted that the inductor L1, the inductor L2 and the capacitor C1 are debugged through impedance matching based on the Smith chart, and the corresponding matching points are different depending on the applied circuit.

[0024] Here, the inductor L1, the capacitor C1 and the inductor L2 constitute a low-power input path, and the inductor L1 and the capacitor C1 constitute a high-power input path. Exemplarily, at the beginning, the antenna outputs a power signal, which may be a first power signal or a second power signal. The power signal enters the first rectifier module and the second rectifier module through two paths, or may only enter the first rectifier module or the second rectifier module. The maximum power point tracking module obtains the output value of the first rectifier module and / or the second rectifier module, and adjusts the resistance of the first rectifier module and / or the second rectifier module in real time. Since the resistance of the first rectifier module and / or the second rectifier module changes, and the power value of the antenna output power signal is different, in order to match the resistance between the antenna output end and the input end of the rectifier module, the power signal spontaneously flows into the low-power input path or the high-power input path. Specifically, when a first input power signal is received, the first input power signal enters the first rectifier module via inductor L1, capacitor C1 and inductor L2; when a second input power signal is received, the second input power signal enters the second rectifier module via inductor L1 and capacitor C1.

[0025] It should be noted that when matching the low-power input path, the high-power input path is open; when matching the high-power input path, the low-power input path is open.

[0026] Compared with the traditional RF energy acquisition circuit which can only process a single narrow range power signal, in the embodiment of the present invention, by using an adaptive impedance matching module, the power flow path can be automatically selected according to different power signals to match different impedance networks, thereby realizing the collection of wide range RF signals, reducing energy loss and effectively improving conversion efficiency.

[0027] Here, the rectifier module includes: a first rectifier module and a second rectifier module; wherein the first rectifier module operates within a power range consisting of a first preset value and a second preset value, and the second rectifier module operates within a power range consisting of a third preset value and a fourth preset value, wherein the first preset value is less than the second preset value, the third preset value is less than the fourth preset value, and the third preset value is greater than or equal to the second preset value; the first rectifier module is used to convert the received first output power signal into a first DC signal based on the resistance value adjusted in real time by the maximum power point tracking module; the second rectifier module is used to convert the received second output power signal into a second DC signal based on the resistance value adjusted in real time by the maximum power point tracking module.

[0028] In one possible implementation, the first rectifier module is a cross-coupled rectifier, and the second rectifier module is a Dickson charge pump rectifier. In this implementation, the cross-coupled rectifier has a higher rectification efficiency for low input power conditions; the Dickson charge pump rectifier has a higher rectification efficiency for high input power conditions. The above combination can improve the overall rectification efficiency within the power input range. It should be understood that other types of rectifiers can also be used in embodiments of the present invention. Exemplarily, when the rectifier module receives a first output power signal, the first rectifier module is used to convert the first output power signal to obtain a first DC signal; when the rectifier module receives a second output power signal, the second rectifier module is used to convert the second output power signal to obtain a second DC signal.

[0029] Figure 3 Schematic diagram of the circuit connection of the first rectifier module provided in an embodiment of the present invention. Figure 3As shown, the first rectifier module includes: an inductor L3, an inductor L4, a capacitor C2, a capacitor C3, a capacitor C4, a PMOS tube MP1, a PMOS tube MP2, an NMOS tube MN1 and an NMOS tube MN2; the first end of the inductor L3 is grounded, and the second end is connected to the first end of the capacitor C1; the inductor L3 and the inductor L4 are electromagnetically coupled, and the first end of the inductor L4 is connected to the first end of the capacitor C2; the second end of the capacitor C2 is respectively connected to the source of the NMOS tube MN1, the source of the PMOS tube MP1, and the source of the PMOS tube MP2 The gate of the NMOS tube MN2 is connected; the second end of the capacitor C1 is respectively connected to the source of the NMOS tube MN2, the source of the PMOS tube MP2, the gate of the NMOS tube MN1 and the gate of the PMOS tube MP1; the drain of the NMOS tube MN1 and the drain of the NMOS tube MN2 are grounded, the drain of the PMOS tube MP1 and the drain of the PMOS tube MP2 are both connected to the first end of the capacitor C3, the first end of the capacitor C3 is connected to the first input end of the maximum power point tracking module; the second end of the capacitor C3 is grounded.

[0030] Figure 4 Schematic diagram of the circuit connection of the second rectifier module provided in an embodiment of the present invention. Figure 4 As shown, the second rectifier module includes: capacitor C5, capacitor C6, capacitor C7, capacitor C8, diode D1, diode D2, diode D3 and diode D4; the second end of the inductor L1 in the adaptive impedance matching module is respectively connected to the first end of the capacitor C5 and the first end of the capacitor C7; the second end of the capacitor C5 is respectively connected to the cathode of the diode D1 and the anode of the diode D2, the anode of the diode D1 is grounded, the cathode of the diode D2 is respectively connected to the anode of the diode D3 and the first end of the capacitor C6, and the second end of the capacitor C6 is grounded; the second end of the capacitor C7 is respectively connected to the cathode of the diode D3 and the anode of the diode D4, the cathode of the diode D4 is connected to the second input end of the maximum power point tracking module, the cathode of the diode D4 is also connected to the first end of the capacitor C8, and the second end of the capacitor C8 is grounded.

[0031] Here, the maximum power point tracking module obtains the output of the first rectifier and the second rectifier in real time, and adjusts the internal resistance of the first rectifier and the second rectifier in real time, so that the first rectifier can efficiently convert the input first output power signal, and the second rectifier can efficiently convert the input second output power signal. Figure 5 The structure of the maximum power point tracking module is described. Figure 5 Schematic diagram of the structural connection of the maximum power point tracking module provided by the embodiment of the present invention. Figure 5As shown, the maximum power point tracking module includes: a power estimator, a sample holder, a comparator, an up-down counter, an open-loop Buck-Boost submodule and an on-time generator; the first input end of the power estimator is connected to the output end of the first rectifier module, the second input end is connected to the output end of the second rectifier module, the output end is respectively connected to the input end of the sample holder and the negative input end of the comparator, the output end of the sample holder is connected to the positive input end of the comparator, the output end of the comparator is connected to the input end of the up-down counter, the four output ends of the up-down counter are connected to the four input ends of the on-time generator, the output end of the on-time generator is connected to the input end of the open-loop Buck-Boost submodule, and the output end of the open-loop Buck-Boost submodule is connected to the input end of the energy storage module.

[0032] Among them, the power estimator is used to obtain the first voltage or the second voltage corresponding to the i-th preset period, the first voltage is generated by using the first DC signal output by the first rectifier module, and the second voltage is generated by the second DC signal output by the second rectifier module, and i is a positive integer greater than 1; the sample and hold device is used to provide the first voltage or the second voltage corresponding to the i-1th preset period to the comparator, and obtain and hold the first voltage or the second voltage corresponding to the i-1th preset period; the comparator is used to compare the first voltage or the second voltage corresponding to the i-th preset period and the first voltage or the second voltage corresponding to the i-1th preset period, and output the comparison result; the add-subtract counter is used to determine the counting signal based on the comparison result output by the comparator; the on-time generator is used to generate the corresponding on-control signal using the counting signal; the open-loop Buck-Boost submodule is used to change the on-time of its internal switch in response to the on-control signal, so as to change the resistance of the first rectifier module or the second rectifier module in real time.

[0033] The working process of the maximum power point tracking module is now explained by taking the process of the maximum power point tracking module adjusting the resistance value of the first rectifier in real time as an example. Specifically, the power estimator obtains the first DC signal output by the first rectifier and the corresponding voltage value multiple times within the preset period to calculate the power corresponding to the first DC signal, and outputs the power value in the form of a first voltage. Assuming that the number of preset periods is Q, the number of corresponding first voltages is Q. Among them, in the i-th preset period, the power estimator outputs the i-th first voltage to the comparator and the sample holder respectively, so that the sample holder holds the i-th first voltage. At the same time, the comparator compares the i-th first voltage with the i-1-th first voltage output by the sample holder. If the i-1-th first voltage is greater than the i-th first voltage, the comparator outputs a high level signal, otherwise, the comparator outputs a low level signal; here, the add-subtract counter includes a D flip-flop and a digital logic gate, and the initial count signal corresponding to the add-subtract counter is 1111, corresponding to the maximum resistance, so that the circuit can start normally in the power-on stage. The add-subtract counter reads the output result of the comparator in each preset cycle and performs an addition and subtraction calculation. If a high-level signal is read, the 4-bit signal of the add-subtract counter controls the programmable capacitor array to generate a 4-bit count signal (the count signal is obtained by adding 1 to the initial count signal, and the upper limit is 4'b1111); if a low-level signal is read, the 4-bit signal of the add-subtract counter controls the programmable capacitor array to generate a 4-bit count signal (the count signal is obtained by subtracting 1 from the initial count signal, and the lower limit is 4'b0000); the 4-bit count signals Q0, Q1, Q2, and Q3 are sent to the on-time generator to generate 4 on-control signals; the 4 on-control signals are used to control the on-time of the internal switch of the open-loop Buck-Boost submodule.

[0034] Figure 6 Schematic diagram of the structural connection of the open-loop Buck-Boost submodule provided by the embodiment of the present invention. Figure 6 As shown, the open-loop Buck-Boost submodule includes: an inductor L5, a switch S1, a switch S2, a switch S3 and a switch S4; the first end of the switch S1 is connected to the output end of the conduction time generator, the second end is respectively connected to the first end of the inductor L5 and the first end of the switch S2, the second end of the switch S2 is grounded, the second end of the inductor L5 is respectively connected to the first end of the switch S3 and the first end of the switch S4, the second end of the switch S3 is grounded, and the second end of the switch S4 is connected to the input end of the energy storage module.

[0035] Here, the open-loop Buck-Boost submodule works in DCM mode, and the 4-bit counting signals Q0, Q1, Q2, and Q3 are respectively sent to the on-time generator to generate 4 on-control signals; the 4 on-control signals are used to control the opening and closing of the internal switches S1, S2, S3, and S4 of the open-loop Buck-Boost submodule; in each cycle. Switch S1, switch S2, switch S3, and switch S4 experience in sequence: stage ①: switch S1 and switch S3 are turned on, and switch S2 and switch S4 are turned off; stage ②: switch S2 and switch S4 are turned on, and switch S1 and switch S3 are turned off; stage ③: switch S1, switch S2, switch S3, and switch S4 are all turned off. Here, the resistance value of the first rectifier module or the second rectifier module is changed by controlling the duration of stage ①. In the case of low power input, the on-time is short and the resistance is large. In the case of high input power, the on-time is long and the resistance is small.

[0036] In a possible implementation, the first DC signal or the second DC signal output by the first rectifier module or the second rectifier module is a current average value. The first DC signal or the second DC signal flows to the energy storage module through the maximum power point tracking module. Specifically, the first DC signal or the second DC signal is successively attenuated into a third DC signal or a fourth DC signal through a power estimator, a sample and hold, a comparator, an add-subtract counter, an open-loop Buck-Boost submodule, and an on-time generator. The third DC signal or the fourth DC signal is stored in the energy storage module. The energy storage module is a lithium battery.

[0037] Here, the first DC signal or the second DC signal flowing out of the open-loop Buck-Boost submodule can be expressed as: The corresponding resistance of the first rectifier module or the second rectifier module can be expressed as: Among them, I in,avg is the value of the third DC signal or the fourth DC signal, I pk is the peak inductor current, DT and T on are the duration of stage ①, where D is the duty cycle, T is the preset period, and V in is the input voltage, L is the power inductor, R in,avg is the resistance value of the first rectifier module or the second rectifier module.

[0038] Please continue to refer to Figure 5 The maximum power point tracking module also includes: a clock signal generating module. The clock signal generating module is connected to the on-time generator to generate a pulse signal with a constant period to control the circuit operating frequency. The length of the pulse signal determines the length of the preset period.

[0039] It should be noted that Figure 5 The power estimator, sample and hold, comparator, up / down counter, clock signal generating module and on-time generator in the circuit are all existing circuit modules. For the sake of brevity, the circuit connection relationship of the existing modules will not be described in detail here.

[0040] In view of the problem that the existing RF energy acquisition circuit has low conversion efficiency and cannot meet the needs of equipment, the present invention provides a RF energy acquisition circuit with adaptive input power shunting. The device acquires RF signals with a wide power range through an electromagnetic wave receiving module to reduce energy loss, and converts the RF signal into a first input power signal or a second input power signal according to the power value, and then uses an adaptive impedance matching module to automatically select a power flow path to adaptively adjust impedance matching to reduce signal transmission loss, and uses a rectifier module for conversion to obtain a first DC signal or a second DC signal, wherein the maximum power point tracking module adjusts the resistance of the rectifier module in real time, and uses the first DC signal or the second DC signal to obtain a third DC signal or a fourth DC signal, and completes wireless charging by storing the third DC signal or the fourth DC signal in an energy storage module. The RF energy acquisition circuit with adaptive input power shunting provided by the present invention can effectively improve conversion efficiency, reduce signal transmission loss, achieve RF signal acquisition with a wide power range, and meet equipment needs.

[0041] In order to verify the conversion effect of the RF energy acquisition circuit with input power adaptive shunting provided by the present invention, the RF energy acquisition circuit with input power adaptive shunting is placed in a simulation environment with an input power range of -15dBm to 15dBm and a signal frequency of 915MHz, and the simulation results are obtained. Figure 7 As shown, the antenna receives the RF signal in the space and converts it into a power signal. The power signal enters the cross-coupled rectifier and / or Dickson rectifier through the adaptive impedance matching module, and then passes through the maximum power point tracking module and is finally stored in the lithium battery. Figure 8 As shown, the maximum conversion efficiency of the RF energy acquisition circuit with adaptive input power diversion is close to 70%, and the minimum conversion efficiency is greater than 20%, indicating that the RF energy acquisition circuit with adaptive input power diversion provided by the present invention can effectively improve the conversion efficiency and realize the acquisition of RF signals in a wide power range.

[0042] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A radio frequency energy harvesting circuit with adaptive input power splitting, characterized in that: include: An electromagnetic wave receiving module, an adaptive impedance matching module, a rectifying module, a maximum power point tracking module and an energy storage module connected in sequence; The electromagnetic wave receiving module is used to receive a radio frequency signal and convert the radio frequency signal into a first input power signal or a second input power signal, wherein the power value of the first input power signal is less than the power value of the second input power signal; The adaptive impedance matching module is used to adaptively adjust the resistance between the output end of the electromagnetic wave receiving module and the input end of the rectifier module according to the received first input power signal or the second input power signal, so as to obtain the corresponding first output power signal or the second output power signal; The rectifier module is used to convert the received first output power signal or the second output power signal based on the resistance value adjusted in real time by the maximum power point tracking module to obtain a first DC signal or a second DC signal; The maximum power point tracking module is further used to generate a third DC signal or a fourth DC signal using the first DC signal or the second DC signal; The energy storage module is used to store the third DC signal or the fourth DC signal and to supply power to an external device.

2. The RF energy harvesting circuit with input power adaptive splitting according to claim 1, characterized in that: The rectifier module includes: a first rectifier module and a second rectifier module; wherein the first rectifier module operates within a power range consisting of a first preset value and a second preset value, and the second rectifier module operates within a power range consisting of a third preset value and a fourth preset value, wherein the first preset value is less than the second preset value, the third preset value is less than the fourth preset value, and the third preset value is greater than or equal to the second preset value; The first rectifier module is used to convert the received first output power signal into the first DC signal based on the resistance value adjusted in real time by the maximum power point tracking module; The second rectifier module is used to convert the received second output power signal into the second DC signal based on the resistance value adjusted in real time by the maximum power point tracking module.

3. The RF energy harvesting circuit with input power adaptive splitting according to claim 2, characterized in that: The adaptive impedance matching module includes: an inductor L1, an inductor L2 and a capacitor C1; The first end of the inductor L1 is connected to the output end of the electromagnetic wave receiving module, and the second end is respectively connected to the first end of the inductor L2, the first end of the capacitor C1 and the input end of the first rectifier module, the second end of the capacitor C1 is grounded, and the second end of the inductor L2 is connected to the input end of the second rectifier module.

4. The RF energy harvesting circuit with input power adaptive splitting according to claim 3, characterized in that: The first rectifier module includes: an inductor L3, an inductor L4, a capacitor C2, a capacitor C3, a capacitor C4, a PMOS transistor MP1, a PMOS transistor MP2, an NMOS transistor MN1 and an NMOS transistor MN2; The first end of the inductor L3 is grounded, and the second end is connected to the first end of the capacitor C1; the inductor L3 and the inductor L4 are electromagnetically coupled, and the first end of the inductor L4 is connected to the first end of the capacitor C2; The second end of the capacitor C2 is respectively connected to the source of the NMOS transistor MN1, the source of the PMOS transistor MP1, the gate of the PMOS transistor MP2 and the gate of the NMOS transistor MN2; The second end of the capacitor C1 is respectively connected to the source of the NMOS transistor MN2, the source of the PMOS transistor MP2, the gate of the NMOS transistor MN1 and the gate of the PMOS transistor MP1; The drain of the NMOS tube MN1 and the drain of the NMOS tube MN2 are grounded, the drain of the PMOS tube MP1 and the drain of the PMOS tube MP2 are both connected to the first end of the capacitor C3, the first end of the capacitor C3 is connected to the first input end of the maximum power point tracking module; the second end of the capacitor C3 is grounded.

5. The RF energy harvesting circuit with input power adaptive splitting according to claim 3, characterized in that: The second rectifier module includes: capacitor C5, capacitor C6, capacitor C7, capacitor C8, diode D1, diode D2, diode D3 and diode D4; The second end of the inductor L1 in the adaptive impedance matching module is connected to the first end of the capacitor C5 and the first end of the capacitor C7 respectively; The second end of the capacitor C5 is connected to the cathode of the diode D1 and the anode of the diode D2 respectively, the anode of the diode D1 is grounded, the cathode of the diode D2 is connected to the anode of the diode D3 and the first end of the capacitor C6 respectively, and the second end of the capacitor C6 is grounded; The second end of the capacitor C7 is respectively connected to the cathode of the diode D3 and the anode of the diode D4, the cathode of the diode D4 is connected to the second input end of the maximum power point tracking module, the cathode of the diode D4 is also connected to the first end of the capacitor C8, and the second end of the capacitor C8 is grounded.

6. The RF energy harvesting circuit with input power adaptive splitting according to claim 2, characterized in that: The maximum power point tracking module includes: a power estimator, a sample and hold, a comparator, an up-down counter, an open-loop Buck-Boost submodule and an on-time generator; The first input end of the power estimator is connected to the output end of the first rectifier module, the second input end is connected to the output end of the second rectifier module, the output end is respectively connected to the input end of the sample and holder and the negative input end of the comparator, the output end of the sample and holder is connected to the positive input end of the comparator, the output end of the comparator is connected to the input end of the add-subtract counter, the four output ends of the add-subtract counter are connected to the four input ends of the on-time generator, the output end of the on-time generator is connected to the input end of the open-loop Buck-Boost submodule, and the output end of the open-loop Buck-Boost submodule is connected to the input end of the energy storage module; The power estimator is used to obtain a first voltage or a second voltage corresponding to an i-th preset period, where the first voltage is generated by using the first DC signal output by the first rectifier module, and the second voltage is generated by using the second DC signal output by the second rectifier module, and i is a positive integer greater than 1; The sample and hold device is used to provide the first voltage or the second voltage corresponding to the i-1th preset period to the comparator, and to obtain and hold the first voltage or the second voltage corresponding to the i-th preset period; The comparator is used to compare the first voltage or the second voltage corresponding to the i-th preset period and the first voltage or the second voltage corresponding to the (i-1)-th preset period, and output a comparison result; The up-down counter is used to determine a counting signal based on a comparison result output by the comparator; The on-time generator is used to generate a corresponding on-time control signal using the counting signal; The open-loop Buck-Boost submodule is used to change the on-time of its internal switch in response to the on-control signal, so as to change the resistance of the first rectifier module or the second rectifier module in real time.

7. The RF energy harvesting circuit with input power adaptive splitting according to claim 6, characterized in that: The open-loop Buck-Boost submodule includes: an inductor L5, a switch S1, a switch S2, a switch S3 and a switch S4; The first end of the switch S1 is connected to the output end of the conduction time generator, the second end is respectively connected to the first end of the inductor L5 and the first end of the switch S2, the second end of the switch S2 is grounded, the second end of the inductor L5 is respectively connected to the first end of the switch S3 and the first end of the switch S4, the second end of the switch S3 is grounded, and the second end of the switch S4 is connected to the input end of the energy storage module.

8. The RF energy harvesting circuit with input power adaptive splitting according to claim 1, characterized in that: The energy storage module is a lithium battery.

9. The RF energy harvesting circuit with input power adaptive splitting according to claim 2, characterized in that: The first rectifier module is a cross-coupled rectifier, and the second rectifier module is a Dickson charge pump rectifier.

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