Radio frequency energy bidirectional digital tuning circuit and radio frequency energy acquisition system
By introducing capacitor increase and decrease circuits into the RF energy harvesting system and using a finite state machine to control capacitor changes, the problems of impedance mismatch and unidirectional tuning are solved, achieving bidirectional tuning and loss reduction, and expanding the operating bandwidth.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI QUANRAY ELECTRONICS
- Filing Date
- 2025-05-20
- Publication Date
- 2026-05-01
AI Technical Summary
Existing radio frequency energy harvesting systems suffer from impedance mismatch and reduced energy transmission efficiency when faced with changes in input impedance. Furthermore, mainstream automatic tuning schemes can only achieve unidirectional tuning and are subject to losses.
By employing a capacitor increase circuit and a capacitor decrease circuit, and controlling the capacitance value in the tuning circuit through a finite state machine, the resonant frequency can be increased or decreased, thereby increasing the operating bandwidth of the tuning circuit.
This system enables bidirectional tuning of the radio frequency energy harvesting system, reduces losses, and expands the operating bandwidth of the tuning circuit.
Smart Images
Figure CN224191917U_ABST
Abstract
Description
A bidirectional digital tuning circuit for radio frequency energy and a radio frequency energy harvesting system Technical Field
[0001] This utility model relates to the field of integrated circuit technology, and in particular to a bidirectional digital tuning circuit for radio frequency energy and a radio frequency energy harvesting system. Background Technology
[0002] Radio frequency (RF) energy harvesting systems extract energy from the surrounding environment, such as sunlight, heat, electromagnetic waves, and mechanical vibrations, and can replace traditional battery-powered solutions, playing a key role in the rise of the Internet of Things.
[0003] In real-world circuit applications, variations in chip manufacturing processes and different PCB substrates can cause changes in the input impedance of RF energy harvesting circuits. These changes in input impedance lead to impedance mismatch, reducing energy transfer efficiency. To avoid this mismatch, the RF energy harvesting system needs to be able to adaptively adjust and achieve automatic tuning.
[0004] Currently, most mainstream automatic tuning solutions use an array of switches and capacitors to achieve automatic tuning. However, this method only allows for unidirectional tuning, and it requires transistors to be turned on as switches. The channel resistance of transistors causes losses, and reducing these losses requires reducing the channel resistance. Reducing the channel resistance necessitates using large-size transistors, which occupies a considerable area. Summary of the Invention
[0005] In view of this, the purpose of this utility model is to provide a bidirectional digital tuning circuit for radio frequency energy and a radio frequency energy acquisition system. By setting a capacitor increase circuit and a capacitor decrease circuit, it is possible to increase or decrease the capacitor of the tuning circuit through a finite state machine after startup, thereby increasing or decreasing the resonant frequency and increasing the operating bandwidth of the tuning circuit.
[0006] In a first aspect, this utility model provides a bidirectional digital tuning circuit for radio frequency energy, including: a capacitance increase circuit, a capacitance decrease circuit, and a finite state machine;
[0007] Wherein, the first port of the capacitance increasing circuit and the third port of the capacitance decreasing circuit are connected in parallel; the second port of the capacitance increasing circuit and the fourth port of the capacitance decreasing circuit are connected in parallel; the finite state machine is connected to the bias voltage terminal of the capacitance increasing circuit and the bias voltage terminal of the capacitance decreasing circuit respectively, and is used to provide bias voltage for the capacitance increasing circuit and the capacitance decreasing circuit.
[0008] The capacitor-increasing circuit is used to increase the capacitance of the radio frequency energy bidirectional digital tuning circuit.
[0009] The capacitance reduction circuit is used to reduce the capacitance of the radio frequency energy bidirectional digital tuning circuit.
[0010] In a preferred embodiment of this invention, the capacitance-increasing circuit includes a first capacitor, a first PMOS transistor, a second PMOS transistor, and a second capacitor connected in series; the first port is connected to the first capacitor, and the second port is connected to the second capacitor.
[0011] In a preferred embodiment of this invention, the capacitance-increasing circuit further includes a first bias circuit and a second bias circuit. The first capacitor and the first PMOS transistor are connected to the input terminal of the first bias circuit, and the second capacitor and the second PMOS transistor are connected to the input terminal of the second bias circuit. The first bias circuit is used to bias the voltage at the input terminal of the first bias circuit to ground, and the second bias circuit is used to bias the voltage at the input terminal of the second bias circuit to ground.
[0012] In a preferred embodiment of this invention, the capacitance reduction circuit includes a third capacitor, a first PVAR transistor, a second PVAR transistor, and a fourth capacitor connected in series; the third port is connected to the third capacitor, and the fourth port is connected to the fourth capacitor.
[0013] In a preferred embodiment of this utility model, the capacitor reduction circuit further includes a third bias circuit and a fourth bias circuit. The third capacitor and the first PVAR transistor are connected to the input terminal of the third bias circuit, and the fourth capacitor and the second PVAR transistor are connected to the input terminal of the fourth bias circuit. The third bias circuit is used to bias the voltage at the input terminal of the third bias circuit to ground, and the fourth bias circuit is used to bias the voltage at the input terminal of the fourth bias circuit to ground.
[0014] In a preferred embodiment of this utility model, the circuit further includes: a first input terminal and a second input terminal; the first input terminal is connected to a first port of the capacitance-increasing circuit and a third port of the capacitance-decreasing circuit, respectively, and the second input terminal is connected to a second port of the capacitance-increasing circuit and a fourth port of the capacitance-decreasing circuit, respectively; the first input terminal and the second input terminal are used to input radio frequency energy to the radio frequency energy bidirectional digital tuning circuit.
[0015] In a preferred embodiment of this utility model, there are multiple capacitor-increasing circuits, and each capacitor-increasing circuit is connected in parallel.
[0016] In a preferred embodiment of this utility model, there are multiple capacitor reduction circuits, and each capacitor reduction circuit is arranged in parallel.
[0017] Secondly, this utility model embodiment also provides a radio frequency energy harvesting system, including: a radio frequency energy receiving circuit and a rectifier, as well as the radio frequency energy bidirectional digital tuning circuit described in the first aspect;
[0018] The radio frequency energy receiving circuit and the radio frequency energy bidirectional digital tuning circuit are connected in series. The input terminal of the rectifier is connected to the output terminal of the radio frequency energy bidirectional digital tuning circuit, and the output terminal of the rectifier is connected to the finite state machine in the radio frequency energy bidirectional digital tuning circuit.
[0019] The radio frequency energy receiving circuit is used to receive radio frequency signals in space;
[0020] The radio frequency energy bidirectional digital tuning circuit is used to generate resonance in the radio frequency signal received by the radio frequency energy receiving circuit, so as to improve the strength of the radio frequency signal.
[0021] The rectifier is used to convert the radio frequency signal output by the radio frequency energy bidirectional digital tuning circuit into a DC signal, and input the DC signal into the finite state machine to control the finite state machine to provide bias voltage for the capacitor increase circuit and the capacitor decrease circuit.
[0022] In a preferred embodiment of this invention, the radio frequency energy receiving circuit includes a serially connected antenna and an impedance matching network; the antenna is used to receive radio frequency signals; and the impedance matching network is used to transmit the radio frequency signals to the radio frequency energy bidirectional digital tuning circuit.
[0023] The present invention provides the following beneficial effects:
[0024] This utility model embodiment provides a bidirectional digital tuning circuit for radio frequency energy. By setting up a capacitor increase circuit and a capacitor decrease circuit, the tuning circuit can be controlled by a finite state machine to increase or decrease the capacitor during startup, thereby increasing or decreasing the resonant frequency and increasing the operating bandwidth of the tuning circuit.
[0025] Other features and advantages of this invention will be set forth in the following description, or some features and advantages may be inferred from the description or determined without doubt, or may be learned by practicing the above-described techniques of this invention.
[0026] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0027] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0028] Figure 1 is a schematic diagram of a radio frequency energy bidirectional digital tuning circuit provided in an embodiment of the present invention;
[0029] Figure 2 is a schematic diagram of a capacitance-increasing circuit provided in an embodiment of this utility model;
[0030] Figure 3 is a schematic diagram of a capacitance reduction circuit provided in an embodiment of this utility model;
[0031] Figure 4 is a schematic diagram of a radio frequency energy harvesting system provided in an embodiment of the present invention;
[0032] Figure 5 is a circuit diagram of a radio frequency energy harvesting system provided in an embodiment of this utility model. Detailed Implementation
[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0034] Currently, most mainstream automatic tuning schemes use an array of switches and capacitors to achieve automatic tuning. This structure has several problems: 1) It can only tune in one direction. At startup, the switches cannot be turned on, so the capacitors in the tuning circuit are not active; that is, the capacitor array is empty at startup. After startup, capacitors at positions 0 to n are turned on based on the tuning result, meaning that only increasing the capacitors is possible. Increasing the capacitors lowers the resonant frequency, while increasing the resonant frequency requires decreasing the capacitors. Since this method cannot reduce the capacitors, it cannot cover tuning frequencies below the startup resonant frequency; 2) It suffers from significant losses. This switch + capacitor method requires transistors to be turned on as switches. The channel resistance of the transistors causes losses, and to reduce losses, the channel resistance needs to be reduced. Reducing the channel resistance (to below 10 ohms) requires using large-size transistors, which occupies a considerable area.
[0035] Based on this, the present invention provides a radio frequency energy bidirectional digital tuning circuit, which can control the circuit startup by increasing or decreasing the capacitance through a finite state machine, thereby controlling the size of the capacitor in the tuning circuit and thus increasing or decreasing the resonant frequency, expanding the operating bandwidth of the tuning circuit.
[0036] To facilitate understanding of this embodiment, a detailed description of a radio frequency energy bidirectional digital tuning circuit disclosed in this utility model embodiment will be provided first.
[0037] Example 1
[0038] This utility model provides a bidirectional digital tuning circuit for radio frequency energy. Figure 1 is a schematic diagram of a bidirectional digital tuning circuit for radio frequency energy provided in this utility model embodiment. As shown in Figure 1, the bidirectional digital tuning circuit for radio frequency energy may include the following structure: a capacitor increase circuit, a capacitor decrease circuit, and a finite state machine;
[0039] Wherein, the first port of the capacitance increasing circuit and the third port of the capacitance decreasing circuit are connected in parallel; the second port of the capacitance increasing circuit and the fourth port of the capacitance decreasing circuit are connected in parallel; the finite state machine is connected to the bias voltage terminal of the capacitance increasing circuit and the bias voltage terminal of the capacitance decreasing circuit respectively, and is used to provide bias voltage for the capacitance increasing circuit and the capacitance decreasing circuit.
[0040] The capacitor-increasing circuit is used to increase the capacitance of the radio frequency energy bidirectional digital tuning circuit.
[0041] The capacitance reduction circuit is used to reduce the capacitance of the radio frequency energy bidirectional digital tuning circuit.
[0042] The circuit further includes: a first input terminal and a second input terminal; the first input terminal is connected to a first port of the capacitance-increasing circuit and a third port of the capacitance-decreasing circuit, respectively, and the second input terminal is connected to a second port of the capacitance-increasing circuit and a fourth port of the capacitance-decreasing circuit, respectively; the first input terminal and the second input terminal are used to input radio frequency energy to the radio frequency energy bidirectional digital tuning circuit.
[0043] Figure 2 is a schematic diagram of a capacitance-increasing circuit provided in an embodiment of this utility model. As shown in Figure 2, the capacitance-increasing circuit includes a first capacitor C1, a first PMOS transistor MP1, a second PMOS transistor MP2, and a second capacitor C2 connected in series. The first port is connected to the first capacitor C1, and the second port is connected to the second capacitor C2. The capacitance-increasing circuit also includes a first bias circuit and a second bias circuit. The first capacitor and the first PMOS transistor are connected to the input terminal of the first bias circuit, and the second capacitor and the second PMOS transistor are connected to the input terminal of the second bias circuit. The first bias circuit is used to bias the voltage at the input terminal of the first bias circuit to ground, and the second bias circuit is used to bias the voltage at the input terminal of the second bias circuit to ground.
[0044] When the tuning circuit starts up, the finite state machine (FSM) can only output a zero-level voltage to the bias voltage terminal of the capacitor-increasing circuit. At this time, the first capacitor and the first PMOS transistor are connected to the input terminal of the first bias circuit. Therefore, the voltages across the first and second PMOS transistors are both low, and the capacitor-increasing circuit is not working. After startup, the capacitance changes are achieved through the output signal of the FSM. For example, when the output signal of the FSM is high, the voltages across the first and second PMOS transistors are high and low, respectively. At this time, the capacitance of the first and second PMOS transistors increases, and the resonant frequency of the tuning circuit decreases. Since there is only a capacitor and no resistance between the first and second ports, ideally there is no loss.
[0045] Figure 3 is a schematic diagram of a capacitance reduction circuit provided in an embodiment of this utility model. As shown in Figure 3, the capacitance reduction circuit includes a third capacitor C3, a first PVAR transistor PVAR1, a second PVAR transistor PVAR2, and a fourth capacitor C4 connected in series. The third port is connected to the third capacitor, and the fourth port is connected to the fourth capacitor. The capacitance reduction circuit also includes a third bias circuit and a fourth bias circuit. The third capacitor and the first PVAR transistor are connected to the input terminal of the third bias circuit, and the fourth capacitor and the second PVAR transistor are connected to the input terminal of the fourth bias circuit. The third bias circuit is used to bias the voltage at the input terminal of the third bias circuit to ground, and the fourth bias circuit is used to bias the voltage at the input terminal of the fourth bias circuit to ground.
[0046] Similarly, when the tuning circuit starts up, the finite state machine (FSM) can only output a zero level to the bias voltage terminal of the capacitor reduction circuit. At this time, the third capacitor and the first PVAR transistor are connected to the input terminal of the third bias circuit. Therefore, the voltages across the first and second PVAR transistors are both low, and the capacitor reduction circuit is not working. After startup, the capacitance changes are achieved through the output signal of the FSM. For example, when the output signal of the FSM is high, the voltages across the first and second PVAR transistors are high and low, respectively. At this time, the capacitance of the first and second PVAR transistors decreases, and the resonant frequency of the tuning circuit increases. Since there is only a capacitor and no resistance between the third and fourth ports, ideally there is no loss.
[0047] Furthermore, there are multiple capacitor-increasing circuits connected in parallel. The FSM provides a high or zero level to each capacitor-increasing circuit. The more capacitor-increasing circuits that receive a high level, the larger the capacitance of the capacitor array formed by the capacitor-increasing circuits in the tuning circuit, the greater the reduction in resonant frequency of the tuning circuit, and the higher frequency tuning the tuning circuit can cover.
[0048] Furthermore, there are multiple capacitor reduction circuits, all connected in parallel. The FSM provides a high or zero level to each capacitor reduction circuit. The more capacitor reduction circuits that provide a high level, the smaller the capacitance of the capacitor array composed of capacitor reduction circuits in the tuning circuit, the greater the amplitude of the resonant frequency increase of the tuning circuit, and the more the tuning circuit can cover lower frequency tuning.
[0049] For example, there are 4 capacitor increasing circuits and 3 capacitor decreasing circuits. In this case, the 4 capacitor increasing units + 3 capacitor decreasing units can achieve 8 levels of adjustment from -3 to 4, effectively expanding the bandwidth.
[0050] It is understood that the bidirectional digital tuning circuit for radio frequency (RF) energy provided in this embodiment is applied to an RF energy harvesting system. The finite state machine provides bias voltages to the capacitor increase circuit and the capacitor decrease circuit based on the DC voltage output by the RF energy harvesting system. The finite state machine pre-sets a correspondence between the DC voltage output by the RF energy harvesting system and the bias voltage. It queries the bias voltage based on the received DC voltage output by the system and outputs the bias voltage to the capacitor increase circuit and the capacitor decrease circuit. For example, when the received DC voltage output by the system is 10V, the corresponding bias voltage is at level 2, meaning the bias voltage output to the two capacitor increase circuits is high, the bias voltage output to the other two capacitor increase circuits is low, and the bias voltage output to the three capacitor decrease circuits is low.
[0051] The radio frequency energy bidirectional digital tuning circuit provided in this embodiment of the utility model is equipped with a capacitor increase circuit and a capacitor decrease circuit. A finite state machine is used instead of a switch to control the start-up of the capacitor increase circuit and the capacitor decrease circuit. This ensures that the capacitor increase circuit and the capacitor decrease circuit contain only capacitors and no resistors or switches, thereby reducing the loss of the tuning circuit. At the same time, by using varactors that increase with voltage and varactors that decrease with voltage, bidirectional tuning is achieved, thereby improving the bandwidth of the tuning circuit.
[0052] Example 2
[0053] This utility model embodiment also provides a radio frequency energy harvesting system; the method is implemented based on the method of the above embodiment; the method focuses on describing the specific implementation of the radio frequency energy bidirectional digital tuning circuit in the radio frequency energy harvesting system.
[0054] Figure 4 is a schematic diagram of a radio frequency energy harvesting system provided in an embodiment of the present invention. As shown in Figure 4, the radio frequency energy harvesting system may include: a radio frequency energy receiving circuit and a rectifier, as well as the radio frequency energy bidirectional digital tuning circuit mentioned in the above embodiment.
[0055] The radio frequency energy receiving circuit and the radio frequency energy bidirectional digital tuning circuit are connected in series. The input terminal of the rectifier is connected to the output terminal of the radio frequency energy bidirectional digital tuning circuit, and the output terminal of the rectifier is connected to the finite state machine in the radio frequency energy bidirectional digital tuning circuit.
[0056] The radio frequency energy receiving circuit is used to receive radio frequency signals in space;
[0057] The radio frequency energy bidirectional digital tuning circuit is used to generate resonance in the radio frequency signal received by the radio frequency energy receiving circuit, so as to improve the strength of the radio frequency signal.
[0058] The rectifier is used to convert the radio frequency signal output by the radio frequency energy bidirectional digital tuning circuit into a DC signal, and input the DC signal into the finite state machine to control the finite state machine to provide bias voltage for the capacitor increase circuit and the capacitor decrease circuit.
[0059] The radio frequency energy receiving circuit includes a serially connected antenna and an impedance matching network; the antenna is used to receive radio frequency signals; the impedance matching network is used to transmit the radio frequency signals to the radio frequency energy bidirectional digital tuning circuit.
[0060] Figure 5 is a circuit diagram of a radio frequency energy harvesting system provided by an embodiment of this utility model. As shown in Figure 5, in the radio frequency energy receiving circuit, the antenna includes an equivalent AC voltage source, an equivalent radiation internal resistance, and an inductive reactance. One end of the equivalent AC voltage source is connected to one end of the equivalent radiation internal resistance, and the other end of the equivalent AC voltage source and the other end of the equivalent radiation internal resistance are connected to the input end of the inductive reactance. The output end of the inductive reactance is connected to the input end of the impedance matching network. Taking one capacitor-increasing circuit and one capacitor-decreasing circuit as an example, the output end of the impedance matching network is connected to the first and second ports of the capacitor-increasing circuit. The third port of the capacitor-decreasing circuit is connected to the first port of the capacitor-increasing circuit, and the fourth port of the capacitor-decreasing circuit is connected to the second port of the capacitor-increasing circuit. The third and fourth ports of the capacitor-decreasing circuit are connected to the input end of the rectifier as the output end of the radio frequency energy bidirectional digital tuning circuit. The output end of the rectifier is connected to the input end of the finite state machine, providing a DC signal (output voltage) to the finite state machine. The finite state machine provides a bias voltage to the capacitor-increasing circuit and the capacitor-decreasing circuit according to the received DC signal.
[0061] Understandably, after receiving the RF signal from the RF energy receiving circuit, the RF energy bidirectional digital tuning circuit does not initially start working. However, since the RF energy bidirectional digital tuning circuit and the rectifier are connected in parallel, the RF energy can be directly input to the rectifier, and the rectifier still has an output voltage. At this point, after inputting the rectifier's output voltage to the finite state machine, the finite state machine provides bias voltage to the capacitor increase circuit and capacitor decrease circuit based on the rectifier's output voltage.
[0062] For example, there are 4 capacitor increase circuits and 3 capacitor decrease circuits. In this case, the 4 capacitor increase units + 3 capacitor decrease units can achieve 8 levels of adjustment from -3 to 4. The finite state machine can select the bias voltage corresponding to the 8 levels according to the preset program and input it to each capacitor increase unit and capacitor decrease unit to achieve the adjustment of the resonant frequency.
[0063] The radio frequency energy harvesting system provided in this embodiment of the invention uses a bidirectional digital tuning circuit for radio frequency energy to tune the resonant frequency, which can adjust the resonant frequency by increasing or decreasing it, thus achieving bidirectional tuning, increasing the adjustment range of the resonant frequency, and expanding the bandwidth of the radio frequency energy harvesting system.
[0064] This application also proposes a radio frequency energy harvesting device, which includes the radio frequency energy harvesting system described above.
[0065] Of course, the radio frequency energy harvesting device proposed in this application embodiment has the corresponding functional modules and beneficial effects of the above-mentioned radio frequency energy harvesting system, which will not be described in detail here.
[0066] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0067] In the several embodiments provided by this utility model, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.
[0068] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0069] In addition, the functional units in the various embodiments of this utility model can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0070] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this utility model, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this utility model. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.
[0071] Finally, it should be noted that the above-described embodiments are merely specific implementations of this utility model, used to illustrate the technical solution of this utility model, and not to limit it. The protection scope of this utility model is not limited thereto. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this utility model. These modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model, and should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.
Claims
1. A radio frequency energy bidirectional digital tuning circuit, characterized in that, include: The system comprises a capacitance-increasing circuit, a capacitance-decreasing circuit, and a finite state machine. The first port of the capacitance-increasing circuit and the third port of the capacitance-decreasing circuit are connected in parallel. The second port of the capacitance-increasing circuit and the fourth port of the capacitance-decreasing circuit are connected in parallel. The finite state machine is connected to the bias voltage terminals of both the capacitance-increasing circuit and the capacitance-decreasing circuit, providing bias voltages for both circuits. The capacitance-increasing circuit increases the capacitance of the bidirectional digital tuning circuit for radio frequency energy. The capacitance-decreasing circuit decreases the capacitance of the bidirectional digital tuning circuit for radio frequency energy.
2. The circuit according to claim 1, characterized in that, The capacitance-increasing circuit includes a first capacitor, a first PMOS transistor, a second PMOS transistor, and a second capacitor connected in series; the first port is connected to the first capacitor, and the second port is connected to the second capacitor.
3. The circuit according to claim 2, characterized in that, The capacitance increase circuit further includes a first bias circuit and a second bias circuit. The first capacitor and the first PMOS transistor are connected to the input terminal of the first bias circuit, and the second capacitor and the second PMOS transistor are connected to the input terminal of the second bias circuit. The first bias circuit is used to bias the voltage at the input terminal of the first bias circuit to ground, and the second bias circuit is used to bias the voltage at the input terminal of the second bias circuit to ground.
4. The circuit according to claim 1, characterized in that, The capacitance reduction circuit includes a third capacitor, a first PVAR transistor, a second PVAR transistor, and a fourth capacitor connected in series; the third port is connected to the third capacitor, and the fourth port is connected to the fourth capacitor.
5. The circuit according to claim 4, characterized in that, The capacitance reduction circuit further includes a third bias circuit and a fourth bias circuit. The third capacitor and the first PVAR transistor are connected to the input terminal of the third bias circuit, and the fourth capacitor and the second PVAR transistor are connected to the input terminal of the fourth bias circuit. The third bias circuit is used to bias the voltage at the input terminal of the third bias circuit to ground, and the fourth bias circuit is used to bias the voltage at the input terminal of the fourth bias circuit to ground.
6. The circuit according to claim 1, characterized in that, The radio frequency energy bidirectional digital tuning circuit further includes: a first input terminal and a second input terminal; the first input terminal is connected to the first port of the capacitance increasing circuit and the third port of the capacitance decreasing circuit, respectively, and the second input terminal is connected to the second port of the capacitance increasing circuit and the fourth port of the capacitance decreasing circuit, respectively; the first input terminal and the second input terminal are used to input radio frequency energy into the radio frequency energy bidirectional digital tuning circuit.
7. The circuit according to claim 1, characterized in that, The number of capacitor-increasing circuits is multiple, and the capacitor-increasing circuits are connected in parallel.
8. The circuit according to claim 1, characterized in that, The number of capacitance reduction circuits is multiple, and the capacitance reduction circuits are arranged in parallel.
9. A radio frequency energy harvesting system, characterized in that, include: A radio frequency (RF) energy receiving circuit and a rectifier, and a bidirectional digital tuning circuit for RF energy as described in any one of claims 1 to 8; wherein the RF energy receiving circuit and the bidirectional digital tuning circuit for RF energy are connected in series, the input terminal of the rectifier is connected to the output terminal of the bidirectional digital tuning circuit for RF energy, and the output terminal of the rectifier is connected to a finite state machine in the bidirectional digital tuning circuit for RF energy; the RF energy receiving circuit is used to receive RF signals in space; the bidirectional digital tuning circuit for RF energy is used to generate resonance in the RF signals received by the RF energy receiving circuit to increase the strength of the RF signals; the rectifier is used to convert the RF signals output by the bidirectional digital tuning circuit for RF energy into DC signals and input the DC signals into the finite state machine to control the finite state machine to provide bias voltages for the capacitor increase circuit and the capacitor decrease circuit.
10. The system according to claim 9, characterized in that, The radio frequency energy receiving circuit includes a serially connected antenna and an impedance matching network; the antenna is used to receive radio frequency signals; the impedance matching network is used to transmit the radio frequency signals to the radio frequency energy bidirectional digital tuning circuit.