Multi-frequency point rectification method, system and circuit based on non-uniform matching transmission line

Abstract

This invention provides a multi-frequency rectification method, system, and circuit based on a non-uniformly matched transmission line, relating to the technical field of microwave wireless power transmission. The method includes: obtaining the input impedance of the rectification back-end circuit at multiple target frequencies; determining the impedance characteristics of the non-uniformly matched transmission line at the target frequencies; calculating the reflection coefficient of the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line; constructing an objective function that minimizes the magnitude of the reflection coefficient at each target frequency, using the constraint that the magnitude of the reflection coefficient at each target frequency is less than a preset threshold; adjusting the geometric parameters of the non-uniformly matched transmission line so that the reflection coefficient at each target frequency meets the preset matching condition, thus completing impedance matching at multiple target frequencies. The rectification method of this invention can alleviate the problems of large size and inter-branch constraints in existing multi-branch structures.

Description

Technical Field

[0001] This invention relates to the field of microwave wireless power transmission technology, and in particular to a multi-frequency rectification method, system and circuit based on a non-uniformly matched transmission line. Background Technology

[0002] With the development of the Internet of Things (IoT) and wireless communication technologies, the energy supply problem for distributed low-power devices is becoming increasingly prominent. Microwave wireless power transfer technology, due to its spatial flexibility and long-distance transmission capabilities, has become an important solution for powering sensor network nodes. The rectifier circuit, as the core component of the energy receiver in microwave wireless power technology, is responsible for converting the received microwave signal into direct current, and its conversion efficiency directly affects the overall system performance.

[0003] Currently, the frequency division of the global radio frequency spectrum exhibits significant regional and industry-specific differences, resulting in poor adaptability and flexibility for single-band rectifier circuits. When multiple frequency bands of energy emission sources exist in space, the application of multi-band and ultra-wideband rectifier circuits promises to utilize a wider range of spectrum and significantly improve the efficiency of energy receiving systems. Therefore, multi-band rectifier circuits have become a major development trend. The impedance matching network in the rectifier circuit plays a crucial role in transmitting RF AC to the rectifier structure. Good impedance matching can reduce energy reflection and significantly improve rectification efficiency. However, since the equivalent input impedance of the rectifier circuit varies at different frequencies, achieving good impedance matching across multiple frequency bands has always been a challenge.

[0004] To achieve multi-band rectification, traditional multi-band rectifier circuits often adopt a multi-branch parallel structure, with branches of different sizes responsible for different frequency bands. However, such a multi-branch topology has objective problems such as large circuit size and mutual constraints between branches when the input signal power of each frequency band is unbalanced, leading to a decrease in efficiency.

[0005] The current mainstream multi-band rectifier design uses a multi-branch structure, with each band equipped with an independently tuned matching network. This type of multi-branch structure has the following drawbacks: when the input power of different bands is unbalanced, the impedance matching effect at the input terminals of each branch varies, affecting the overall circuit matching and reducing the overall RF-DC efficiency. Furthermore, the circuit design process for multi-branch structures is complex, requiring impedance matching for each band before overall integration; the large circuit board size hinders device miniaturization. Therefore, a rectification method is urgently needed to solve the problems of large size and inter-branch constraints inherent in traditional branch structures. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a multi-frequency rectification method, system and circuit based on non-uniform matching transmission lines, so as to alleviate the problems of large size and mutual constraints between branches in the existing multi-branch structure.

[0007] In a first aspect, embodiments of the present invention provide a multi-frequency rectification method based on a non-uniformly matched transmission line, the method comprising: Obtain the input impedance of the rectifier back-end circuit under multiple target frequency points; the rectifier back-end circuit includes a cascaded rectifier network, a harmonic suppression network, and an output load; the input impedance is the target load impedance of the non-uniformly matched transmission line; the non-uniformly matched transmission line includes multiple cascaded trapezoidal gradient transmission lines, and the non-uniformly matched transmission line is connected to the rectifier network. Determine the impedance characteristics of the non-uniformly matched transmission line at the target frequency. Calculate the reflection coefficient at the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line. Construct an objective function that minimizes the magnitude of the reflection coefficient at each target frequency. With the constraint that the magnitude of the reflection coefficient at each target frequency is less than a preset threshold, adjust the geometric parameters of the non-uniform matching transmission line so that the reflection coefficient at each target frequency meets the preset matching condition, thereby completing the impedance matching of multiple target frequencies.

[0008] Optionally, the impedance characteristics of the non-uniformly matched transmission line at the target frequency are determined using differential theory calculation methods, including: Divide each trapezoidal gradient transmission line into multiple uniform transmission line segments and calculate the transition matrix of each uniform transmission line segment. Based on the transfer matrix of a small segment of a uniform transmission line, determine the transfer matrix of a single-segment trapezoidal gradient transmission line. Based on the transfer matrix of a single-segment trapezoidal gradient transmission line, determine the overall transfer matrix of a non-uniformly matched transmission line.

[0009] Optionally, the transfer matrix of a small segment of the uniform transmission line is calculated, including: The characteristic impedance of a small segment of a uniform transmission line is determined according to the first formula. The first formula is:

[0010] in, The width of a small segment of a uniform transmission line is given by h, where h is the thickness of the circuit board. The specific dielectric constant of the circuit board; The transfer matrix of a small segment of a uniform transmission line is determined based on the second and third formulas. The second formula is:

[0011] in, Let be the transfer matrix for the i-th uniform transmission line segment; The third formula is:

[0012] in, Phase constant, For the length of a small segment of a uniform transmission line, This refers to the electrical length of a small segment of a uniform transmission line.

[0013] Optionally, the reflection coefficient at the input port of the non-uniformly matched transmission line is calculated, including: Calculate the input impedance of the input port of the non-uniformly matched transmission line according to the fourth formula; The fourth formula is:

[0014] Among them, For elements of the overall transfer matrix of a non-uniformly matched transmission line, This refers to the target load impedance at the corresponding target frequency. The reflection coefficient is calculated using the fifth formula. The fifth formula is:

[0015] in, Source impedance

[0016] Optionally, the number of target frequency points is 2 to 8, and the non-uniform matching transmission line is a combination of multiple trapezoidal transmission lines, with the number of transmission line segments not less than the number of target frequency points.

[0017] Optional geometric parameters for non-uniformly matched transmission lines include the starting width, ending width, length, and total number of segments for each trapezoidal transmission line.

[0018] Optionally, the preset matching condition is that the magnitude of the reflection coefficient at multiple target frequency points is less than -10dB.

[0019] Optionally, after completing impedance matching at multiple frequency points, when a non-uniformly matched transmission line simultaneously receives RF signals from one or more target frequency points, the reflection coefficients at each target frequency point satisfy the conjugate matching condition, and the rectified DC output is the sum of the DC components corresponding to each target frequency point.

[0020] Secondly, embodiments of the present invention also provide a multi-frequency rectification system based on a non-uniformly matched transmission line, comprising: The acquisition unit is used to acquire the input impedance of the rectifier back-end circuit under multiple target frequency points; the rectifier back-end circuit includes a cascaded rectifier network, a harmonic suppression network and an output load; the input impedance is the target load impedance of the non-uniformly matched transmission line; the non-uniformly matched transmission line includes multiple cascaded trapezoidal gradient transmission lines and is connected to the rectifier network. The calculation unit is used to calculate the reflection coefficient of the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line. The adjustment unit is used to construct an objective function that minimizes the magnitude of the reflection coefficient at each target frequency point. With the magnitude of the reflection coefficient at each target frequency point being less than a preset threshold as a constraint, the geometric parameters of the non-uniform matching transmission line are adjusted so that the reflection coefficient at each target frequency point meets the preset matching condition, thereby completing the impedance matching of multiple target frequencies.

[0021] Thirdly, embodiments of the present invention also provide a circuit, comprising: a cascaded non-uniformly matched transmission line circuit, a rectifier circuit, and a harmonic suppression circuit, wherein the non-uniformly matched transmission line network is used to receive multi-frequency signals and perform impedance matching before outputting them to the rectifier network, and after filtering by the harmonic suppression network, outputting them to the output load; the non-uniformly matched transmission line network employs the multi-frequency rectification method based on non-uniformly matched transmission lines as described in the first aspect or any embodiment of the first aspect.

[0022] The embodiments of the present invention bring the following beneficial effects: This invention proposes a multi-frequency rectification method, system, and circuit based on non-uniformly matched transmission lines. The method pre-extracts the input impedance of the rectifier back-end circuit as the target load impedance of the non-uniformly matched transmission line. Based on the impedance characteristics of the non-uniformly matched transmission line and the target load impedance, it determines the reflection coefficient of the input port. Finally, it optimizes the geometric parameters of multiple transmission lines with the objective function of minimizing the magnitude of the reflection coefficient at each target frequency and the constraint that the magnitude of the reflection coefficient is less than a preset threshold. This allows the conjugate matching conditions of multiple target frequencies to be satisfied simultaneously through a single branch. Compared to traditional multi-branch parallel structures, this invention, through a single series branch, not only eliminates the "barrel effect" caused by the imbalance of input power in each frequency band, but also avoids the complex process of designing and debugging multiple branches separately. This significantly reduces circuit size and design costs, providing an efficient, compact, and robust solution for multi-band wireless power reception in low-power devices such as IoT sensors.

[0023] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 A flowchart illustrating the multi-frequency rectification method based on a non-uniformly matched transmission line provided in this application embodiment; Figure 2 A simulation schematic diagram of the single-branch multi-band rectifier circuit structure based on a non-uniformly matched transmission line provided in this application embodiment; Figure 3 A schematic diagram of a single-segment trapezoidal gradient transmission line provided in an embodiment of this application; Figure 4 A schematic diagram of a cascaded circuit of multiple non-uniform trapezoidal gradient lines provided in an embodiment of this application; Figure 5 A simulation schematic diagram of the single-branch multi-band rectifier circuit structure based on a non-uniformly matched transmission line provided in this application embodiment; Figure 6 The simulation and measured comparison curves of the overall efficiency of the rectifier circuit provided in the embodiments of this application are shown. Figure 7 The output power test results of the rectifier circuit provided in the embodiment of the present invention under multi-frequency input conditions are shown in the figure. Figure 8 The structural block diagram of a multi-frequency rectification system based on a non-uniformly matched transmission line provided in the embodiments of this application is shown. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The mainstream multi-band rectifier design uses a multi-branch structure, with each band equipped with an independently tuned matching network. This type of multi-branch structure has the following drawbacks: when the input power of different frequency bands is unbalanced, the impedance matching effect at the input terminals of each branch varies, affecting the overall circuit matching and reducing the overall RF-DC efficiency. The circuit of this invention uses a single-branch structure; regardless of the significant difference in input power at each frequency point, the rectified DC at each frequency is linearly superimposed, and there is no issue of the overall output being affected by a lower power at a particular frequency point. The design process is complex, requiring impedance matching for each frequency band before overall integration; the circuit board size is large, which is not conducive to device miniaturization.

[0029] Based on this, the present invention provides a multi-frequency rectification method, system and circuit based on non-uniform matching transmission lines, which can solve the problems of reducing the size of the circuit and the mutual constraints between branches.

[0030] To facilitate understanding of this embodiment, a multi-frequency rectification method based on a non-uniformly matched transmission line, as disclosed in this embodiment of the invention, will first be described in detail.

[0031] Figure 1 A flowchart of the multi-frequency rectification method based on non-uniform matched transmission lines provided in the embodiments of this application is shown below. Figure 1 As shown, the method may include: S120: Obtain the input impedance of the rectifier back-end circuit under multiple target frequency points.

[0032] Figure 2 This is a simulation diagram illustrating the structural principle of a single-branch multi-band rectifier circuit based on a non-uniformly matched transmission line, provided in an embodiment of this application. Figure 2 As shown, the rectifier circuit includes an impedance matching network, a rectifier network, a harmonic suppression network, and an output load. The impedance matching network consists of multiple cascaded transmission lines. These transmission lines are connected sequentially, and the entire rectifier circuit uses a single branch.

[0033] The rectifier circuit receives multi-band radio frequency signals at its input, transmits them to the rectifier network via an impedance matching network for rectification, and then outputs DC power after filtering by a harmonic suppression network. The impedance matching network serves to transmit the radio frequency AC signal to the rectifier structure; good impedance matching reduces energy reflection, thus significantly improving rectification efficiency.

[0034] The impedance matching network in this embodiment of the invention is composed of multiple trapezoidal tapered transmission lines, achieving multi-band impedance matching from the input port to the rectifier network. This allows a single branch of the rectifier circuit to match more than two frequency points. Increasing the number of trapezoidal tapered microstrip lines in the non-uniform matching transmission lines can improve the matching frequency points further. The rectifier network in this embodiment preferably uses diodes or Schottky diodes with certain bandwidth characteristics, preferably matching two or more frequency points, up to a maximum of eight.

[0035] The rectifier back-end circuit includes a cascaded rectifier network, a harmonic suppression network, and an output load; the input impedance is the target load impedance of the non-uniformly matched transmission line.

[0036] The rectifier network in this embodiment of the invention can employ single-diode series rectification, single-diode parallel rectification, full-bridge rectification, or voltage doubler rectification. Preferably, this embodiment employs a voltage doubler rectifier circuit.

[0037] In this embodiment of the invention, the output load refers to a fixed resistance value assumed when designing the matching network, which enables the rectifier circuit to achieve a preset rectification efficiency at a specified input power. However, in practical applications, the output load can be a fixed resistive load (e.g., directly powering an LED or sensor) or a variable energy storage element (e.g., a rechargeable battery or supercapacitor). When the load changes, the actual input impedance of the rectifier circuit will deviate from the design value, thus affecting the matching effect. Therefore, a DC-DC converter or power management circuit can be cascaded at the output of the rectifier circuit to adjust the equivalent load impedance and stabilize it near the optimal load value, thereby maintaining the rectification efficiency. The above-mentioned technical means are conventional designs in the art and do not affect the application of the core matching method of this invention.

[0038] In practical applications, the target frequency can be any frequency point in the 0.9–5.8 GHz band, such as 0.9 GHz, 1.8 GHz, 2.4 GHz, 3.5 GHz, and 5.8 GHz.

[0039] S140: Determine the impedance characteristics of the non-uniformly matched transmission line at the target frequency.

[0040] Based on the Bode-Fano theory, a theoretical limit for the minimum achievable reflection coefficient within a given bandwidth is given. In this embodiment, a large number of non-target frequency ranges exist within the 0.9–5.8 GHz band. According to this theory, the reflection coefficient of non-target frequency bands is sacrificed to obtain better impedance matching at the five target frequency points. This paper uses the transfer matrix method to theoretically analyze the passband characteristics of the target non-uniformly matched transmission line.

[0041] In this embodiment, the impedance characteristics of a non-uniformly matched transmission line at the target frequency can be determined using an electromagnetic modeling method, which may include: Divide each trapezoidal gradient transmission line into multiple transmission line segments and calculate the transition matrix of the uniform transmission line segments. Based on the transfer matrix of a small segment of a uniform transmission line, determine the transfer matrix of a single-segment trapezoidal gradient transmission line. Based on the transfer matrix of a single-segment trapezoidal gradient transmission line, determine the overall transfer matrix of a non-uniformly matched transmission line.

[0042] A transfer matrix, also known as a transmission matrix or cascade matrix, is a parametric matrix used to describe the voltage and current relationship between the input and output of a two-port network.

[0043] Figure 3 This is a schematic diagram of a single-segment trapezoidal gradient transmission line provided in an embodiment of this application. The trapezoidal gradient line, with a starting width of W1, an ending width of W2, and a length of L, is divided into N equal segments of length L. l Small segments. As N approaches infinity, each small segment can be approximated as a uniform transmission line.

[0044] In a single-segment trapezoidal gradient transmission line, the length of the i-th uniform segment is:

[0045] The width of the i-th uniform segment is obtained by linear interpolation:

[0046] For a given microstrip substrate, the characteristic impedance is calculated from the width using the quasi-static characteristic impedance formula. The effective dielectric constant is calculated using the microstrip formula. This allows us to obtain the phase constants of each segment. With electrical length .

[0047]

[0048]

[0049]

[0050] w represents the width of the circuit board used, and h represents the thickness of the circuit board. This is the specific permittivity of the circuit board. Using the transfer matrix formula for a uniform transmission line segment, the matrix for the i-th segment is:

[0051] By cascading all the uniform segments, we obtain the transfer matrix of the entire single-segment trapezoidal gradient transmission line:

[0052] Figure 4 This is a schematic diagram of a cascaded circuit of multiple non-uniform trapezoidal gradient lines provided in an embodiment of this application. Figure 4 As shown, when multiple tapered lines are cascaded, the total transfer matrix of a non-uniformly matched transmission line is the product of the transfer matrices of each tapered line:

[0053] S160: Calculate the reflection coefficient at the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line. A non-uniformly matched transmission line can be represented as a two-port network with a known transfer matrix. The source impedance Z is known. s With load impedance The input impedance can be derived from the ABCD parameters. :here It includes the rectifier network at the back end of the non-uniformly matched transmission line, the harmonic suppression network, and the overall load resistance of the rectifier circuit.

[0054]

[0055] Finally, the input reflection coefficient is:

[0056] S180: Construct an objective function that minimizes the magnitude of the reflection coefficient at each target frequency. With the constraint that the magnitude of the reflection coefficient at each target frequency is less than a preset threshold, adjust the geometric parameters of the non-uniform matching transmission line so that the reflection coefficient at each target frequency meets the preset matching condition, and complete the impedance matching of multiple target frequencies.

[0057] In this embodiment, the constraint condition for the reflection coefficient magnitude to be less than a preset threshold can be whether the reflection coefficient approaches 0. If not, the set parameters of the non-uniformly matched transmission line are adjusted to complete multi-band precise impedance matching.

[0058] As an optional implementation, the impedance characteristics of a non-uniformly matched transmission line at the target frequency are determined using an electromagnetic modeling method, including: Divide each trapezoidal gradient transmission line into multiple transmission line segments and calculate the transition matrix of the uniform transmission line segments. Based on the transfer matrix of a small segment of a uniform transmission line, determine the transfer matrix of a single-segment trapezoidal gradient transmission line. Based on the transfer matrix of a single-segment trapezoidal gradient transmission line, determine the overall transfer matrix of a non-uniformly matched transmission line.

[0059] As an optional implementation, calculating the transfer matrix of a small segment of a uniform transmission line includes: The characteristic impedance of a small segment of a uniform transmission line is determined according to the first formula. The first formula is:

[0060] in, The width of the small uniform transmission line segment is given by h, where h is the thickness of the circuit board. The specific dielectric constant of the circuit board; The transfer matrix of a small segment of a uniform transmission line is determined based on the second and third formulas. The second formula is:

[0061] in, Let be the transfer matrix of the i-th uniform transmission line segment; The third formula is:

[0062] in, Phase constant, For the length of a small segment of a uniform transmission line, This refers to the electrical length of a small segment of a uniform transmission line.

[0063] Optionally, the reflection coefficient at the input port of the non-uniformly matched transmission line is calculated, including: Calculate the input impedance of the input port of the non-uniformly matched transmission line according to the fourth formula; The fourth formula is:

[0064] Among them, For elements of the overall transfer matrix of a non-uniformly matched transmission line, This refers to the target load impedance at the corresponding target frequency. The reflection coefficient is calculated using the fifth formula. The fifth formula is:

[0065] in, Source impedance

[0066] As an optional implementation, the number of target frequency points is 2 to 8, and the non-uniform matching transmission line is a multi-segment trapezoidal transmission line, with the number of segments of the transmission line not less than the number of target frequency points.

[0067] As an alternative implementation, the geometric parameters of a non-uniformly matched transmission line include the start width, end width, length, and total number of segments.

[0068] As an optional implementation, the preset matching condition is that the reflection coefficient modulus at multiple target frequency points is less than -10dB.

[0069] As an optional implementation, after completing impedance matching at multiple frequency points, when a non-uniformly matched transmission line simultaneously receives radio frequency signals from one or more target frequency points, the reflection coefficients at each target frequency point satisfy the conjugate matching condition, and the rectified output DC is the sum of the DC components corresponding to each target frequency point.

[0070] In this embodiment of the invention, the input impedance of the rectifier back-end circuit varies at different frequencies. However, as a linear passive network, the output impedance of the non-uniformly matched transmission line is a function of frequency. By optimizing the geometric parameters of the non-uniformly matched transmission line, its output impedance can be made equal to the conjugate value of the corresponding input impedance of the rectifier back-end circuit at multiple discrete frequency points. Therefore, in this embodiment of the invention, when the input has only a single design frequency point, the output impedance of the impedance matching network at that frequency point automatically satisfies conjugate matching, resulting in efficient energy transfer. When the input includes multiple target frequencies, the non-uniformly matched transmission network provides its own corresponding output impedance for each frequency point, and all frequencies simultaneously satisfy conjugate matching, ensuring efficient rectification of their respective energy.

[0071] For example, let's take five target frequency points as an example: 0.9GHz, 1.8GHz, 2.4GHz, 3.5GHz, and 5.8GHz.

[0072] In this embodiment, a cascaded trapezoidal configuration is used to form the non-uniformly matched transmission line. 2-10 trapezoidal transmission line models are employed to create the non-uniformly matched transmission line. The thinnest part of the cascaded non-uniformly matched transmission line must be ≥0.2mm, while the thickest part can be adjusted based on simulation results. The characteristic impedance of the transmission line input port is 50 ohms, and the width of other parts of the line is also 50 ohms. Considering an input power of 10dBm, the rectifier circuit topology is chosen as a voltage doubler topology, which has the advantages of stable input impedance and high output voltage. HSMS286C Schottky diodes with low junction capacitance (0.18pF) and series resistance (5Ω) are selected, along with a high-precision 820pF surface-mount capacitor, to form a voltage doubler rectifier circuit, achieving efficient rectification at multiple target frequencies across a wide frequency range.

[0073] Here, the surface-mount capacitor can be selected with a cutoff frequency much higher than the operating frequency. In this embodiment, the highest operating frequency is 5.8GHz, so the capacitor's cutoff frequency should be greater than 5.8GHz (e.g., 6GHz). The capacitor value should be chosen to be as much larger as possible than the junction capacitance of the rectifier Schottky diode used. In this embodiment, an HSMS286C Schottky diode junction capacitance (0.18pF) is used, therefore, the surface-mount capacitor selected in this embodiment is 820pF.

[0074] The rectifier Schottky diode can be selected based on the input power and the rectification operating frequency, and is not limited to the Schottky rectifier diode device in the embodiment (nor is it limited to the type, such as gallium nitride Schottky diode, gallium arsenide Schottky diode, etc.).

[0075] The harmonic suppression network employs a low-pass filter constructed from dual-branch fan-shaped microstrip lines. By suppressing high-order harmonic output, it reflects these harmonics back to the diode rectifier network for re-rectification, thereby improving rectification efficiency. The fan-shaped microstrip line structure features wide bandwidth characteristics, making it suitable for filtering multi-band high-order harmonics across a wide frequency range.

[0076] The harmonic suppression network can be a Class F harmonic suppression network. The operating characteristics of a Class F harmonic suppression network are: infinite impedance and only voltage components exist when the fundamental frequency is present; zero impedance and only current components exist when even harmonics are present; and infinite impedance and only voltage components exist when fundamental harmonics are present. This process ensures that the voltage and current are orthogonal at the input port, thereby improving the overall conversion efficiency of the rectifier circuit.

[0077] Alternatively, a low-pass filter network can be used, in which only DC is output to the back end, while other fundamental and harmonic components are reflected back to the rectifier network. This patent does not impose any limitations on this approach.

[0078] The sector-shaped input port in this embodiment also uses a characteristic impedance of 50 ohms, with a sector angle of 75°. The sector angle can be selected from 0° (typically an open circuit) to 85°, depending on whether harmonic components in multiple operating frequency bands such as 0.9GHz, 1.8GHz, 2.4GHz, 3.5GHz, and 5.8GHz can be suppressed. Generally, if the fundamental and harmonic components are suppressed below -20dB, only DC output is used.

[0079] By optimizing the width and length of each trapezoidal gradient microstrip line segment through simulation, the impedance matching network achieves the minimum input reflection coefficient and the highest energy transfer efficiency in the target frequency bands (such as 0.9GHz, 1.8GHz, 2.4GHz, 3.5GHz, and 5.8GHz). Figure 5 This is a simulation diagram illustrating the structural principle of a single-branch multi-band rectifier circuit based on a non-uniformly matched transmission line, provided in an embodiment of this application. Figure 5 As shown, the start width and end width of a non-uniformly matched transmission line can both be 1 / 2. The parameters for the non-uniformly matched transmission line circuit are set as follows, where, It is 0.8mm. It is 7.10693mm. .198 , It is 8.94957mm. It is 1.624mm. It is 11.7412 mm. It is 0.604mm. It is 4.63852mm. It is 3.434mm. It is 2.02704 mm.

[0080] Figure 6 The simulation and measured comparison curves of the overall efficiency of the rectifier circuit provided in the embodiments of this application are shown. Figure 6 As shown, the rectifier circuit of this embodiment of the invention achieves rectification efficiencies of 67.5%, 66.5%, 58.5%, 58.6%, and 51.2% at 0.9GHz, 1.8GHz, 2.4GHz, 3.5GHz, and 5.8GHz frequencies, respectively, with an input power of 10dBm.

[0081] To verify the performance of the rectifier circuit of this invention under simultaneous input conditions at multiple frequency points, this embodiment tested the output DC power and rectification efficiency of the rectifier circuit when power was injected simultaneously at 1 to 5 target frequency points. The test conditions are as follows: The input power at each frequency is 3dBm; The target frequencies are: 0.9GHz, 1.8GHz, 2.4GHz, 3.5GHz, and 5.8GHz; The output load is a fixed resistive load (R). L =1000 Ω); Figure 7 The diagram shows the output power test results of the rectifier circuit provided in this embodiment of the invention under multi-frequency input conditions. Figure 7 Figures (a) to (e) in the figure correspond to the output power curves when different numbers of target frequency points are input simultaneously: (a) The figure shows the output power curve when the input is a single target frequency (0.9 GHz). When the input power is 3 dBm, the output DC power Pout = 0.106 mW and the rectification efficiency is 52.933%.

[0082] (b) The figure shows the output power curves when two target frequencies (0.9 GHz and 1.8 GHz) are input simultaneously. When the input power at each frequency is 3 dBm, the output DC power Pout = 0.233 mW and the rectification efficiency is 58.454%.

[0083] (c) The figure shows the output power curves when three target frequencies (0.9 GHz, 1.8 GHz, and 2.3 GHz) are input simultaneously. When the input power at each frequency is 3 dBm, the output DC power Pout = 0.358 mW, and the rectification efficiency is 59.841%.

[0084] (d) The figure shows the output power curves when four target frequencies (0.9 GHz, 1.8 GHz, 2.3 GHz, and 3.5 GHz) are input simultaneously. When the input power at each frequency is 3 dBm, the output DC power Pout = 0.453 mW, and the rectification efficiency is 56.744%.

[0085] (e) The figure shows the output power curves when five target frequency points (0.9 GHz, 1.8 GHz, 2.3 GHz, 3.5 GHz and 5.8 GHz) are input simultaneously. When the input power at each frequency point is 3 dBm, the output DC power Pout = 0.593 mW and the rectification efficiency is 59.462%.

[0086] This embodiment verifies the following technical effects: First, the non-uniform matching transmission line proposed in this invention can independently match and rectify any single or multiple radio frequency signals within the target frequency set, and does not have the problem of affecting the overall output due to power loss or power imbalance at a certain frequency point, as is the case in traditional multi-branch structures.

[0087] Second, under the condition of simultaneous input of multiple frequency points, the RF power of each frequency point can be linearly superimposed at the same rectifier back end, and the output DC power is the sum of the contributions of each frequency point. The rectification efficiency is basically the same as that when using single-frequency input.

[0088] Third, the present invention has good power superposition characteristics and stable rectification efficiency in multi-band radio frequency energy environments, and is suitable for complex radio frequency environments in actual space where multiple frequency band energy sources coexist.

[0089] Figure 8 This is a structural block diagram of a multi-frequency rectification system based on a non-uniformly matched transmission line, provided in an embodiment of this application. Figure 8 As shown, the system may include: The acquisition unit 810 is used to acquire the input impedance of the rectifier back-end circuit under multiple target frequency points; the rectifier back-end circuit includes a cascaded rectifier network, a harmonic suppression network and an output load, and the input impedance is the target load impedance of the non-uniform matching transmission line; the non-uniform matching transmission line includes multiple cascaded trapezoidal gradient transmission lines; the non-uniform matching transmission line is connected to the rectifier network. Determining unit 830 is used to determine the impedance characteristics of a non-uniformly matched transmission line at the target frequency. The calculation unit 850 is used to calculate the reflection coefficient of the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line. The adjustment unit 870 is used to construct an objective function that minimizes the magnitude of the reflection coefficient at each target frequency point. With the magnitude of the reflection coefficient at each target frequency point being less than a preset threshold as a constraint, the geometric parameters of the non-uniform matching transmission line are adjusted so that the reflection coefficient at each target frequency point meets the preset matching condition, thereby completing the impedance matching of multiple target frequencies.

[0090] This invention also provides a circuit comprising: a cascaded non-uniformly matched transmission line circuit, a rectifier circuit, and a harmonic suppression circuit. The non-uniformly matched transmission line network is used to receive multi-frequency signals and perform impedance matching before outputting them to the rectifier network. After being filtered by the harmonic suppression network, the signals are output to the output load. The non-uniformly matched transmission line network employs a multi-frequency rectification method based on non-uniformly matched transmission lines.

[0091] The system provided in this application embodiment has the same implementation principle and technical effects as the aforementioned method embodiment. For the sake of brevity, any parts not mentioned in the system embodiment can be referred to the corresponding content in the aforementioned method embodiment.

[0092] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0093] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0094] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0095] The foregoing has described specific embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0096] In the description of the embodiments of this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments of this application. In the embodiments of this application, the illustrative expressions 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 a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in the embodiments of this application, as well as the features of different embodiments or examples.

[0097] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of embodiments of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0098] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing custom logic functions or processes, and the scope of preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order according to the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0099] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0100] It should be noted that the terminals involved in the embodiments of this application may include, but are not limited to, personal computers (PCs), personal digital assistants (PDAs), wireless handheld devices, tablet computers, mobile phones, MP3 players, MP4 players, etc.

[0101] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between devices or units may be electrical, mechanical, or other forms.

[0102] Furthermore, the functional units in the various embodiments of this application can be integrated into a single processor, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The integrated units described above can be implemented in hardware or in a combination of hardware and software functional units.

[0103] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of this application. 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.

[0104] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present application should be included within the scope of protection of the present application.

Claims

1. A multi-frequency rectification method based on a non-uniform matched transmission line, characterized in that, include: The input impedance of the rectifier back-end circuit under multiple target frequency points is obtained; the rectifier back-end circuit includes a cascaded rectifier network, a harmonic suppression network and an output load; the input impedance is the target load impedance of the non-uniformly matched transmission line; the non-uniformly matched transmission line includes multiple cascaded trapezoidal gradient transmission lines, and the non-uniformly matched transmission line is connected to the rectifier network. Determine the impedance characteristics of the non-uniformly matched transmission line at the target frequency. Calculate the reflection coefficient of the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line. An objective function is constructed to minimize the magnitude of the reflection coefficient at each of the target frequencies. The geometric parameters of the non-uniform matching transmission line are adjusted so that the reflection coefficient at each of the target frequencies meets the preset matching condition, thereby completing the impedance matching of multiple target frequencies.

2. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 1, characterized in that, The impedance characteristics of the non-uniformly matched transmission line at the target frequency are determined using differential theory calculation methods, including: Each trapezoidal gradient transmission line segment is divided into multiple uniform transmission line segments, and the transition matrix of each uniform transmission line segment is calculated. Based on the transmission transfer matrix of the small segment of the uniform transmission line, determine the transfer matrix of the single-segment trapezoidal gradient transmission line. Based on the transfer matrix of the single-segment trapezoidal gradient transmission line, the overall transfer matrix of the non-uniformly matched transmission line is determined.

3. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 2, characterized in that, The calculation of the transfer matrix of the uniform transmission line segment includes: The characteristic impedance of the small segment of the uniform transmission line is determined according to the first formula; The first formula is: in, h is the width of the uniform transmission line segment, and h is the thickness of the circuit board. The specific dielectric constant of the circuit board; The transfer matrix of the uniform transmission line segment is determined according to the second and third formulas; The second formula is: in, Let be the transfer matrix for the i-th uniform transmission line segment; The third formula is: in, Phase constant, For the length of a small segment of a uniform transmission line, This refers to the electrical length of a small segment of a uniform transmission line.

4. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 3, characterized in that, The calculation of the reflection coefficient at the input port of the non-uniformly matched transmission line includes: Calculate the input impedance of the non-uniformly matched transmission line input port according to the fourth formula; The fourth formula is: Among them, The elements are the overall transfer matrix of the non-uniformly matched transmission line. This refers to the target load impedance at the corresponding target frequency. The reflection coefficient is calculated according to the fifth formula; The fifth formula is: in, The input impedance of the input port. The source impedance is denoted as .

5. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 1, characterized in that, The number of target frequency points is 2 to 8, and the non-uniform matching transmission line is a combination of multiple trapezoidal transmission lines, the number of segments of the transmission line being no less than the number of target frequency points.

6. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 5, characterized in that, The geometric parameters of the non-uniformly matched transmission line include the starting width, ending width, length, and total number of segments of each trapezoidal transmission line.

7. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 1, characterized in that, The preset matching condition is that the magnitude of the reflection coefficient at the multiple target frequency points is less than -10dB.

8. The multi-frequency rectification method based on a non-uniform matched transmission line according to claim 1, characterized in that, After impedance matching at multiple frequency points is completed, when the non-uniformly matched transmission line simultaneously receives radio frequency signals from one or more of the target frequency points, the reflection coefficients at each target frequency point satisfy the conjugate matching condition, and the rectified output DC is the sum of the DC components corresponding to each target frequency point.

9. A multi-frequency rectification system based on a non-uniformly matched transmission line, characterized in that, include: The acquisition unit is used to acquire the input impedance of the rectifier back-end circuit under multiple target frequency points; the rectifier back-end circuit includes a cascaded rectifier network, a harmonic suppression network and an output load; the input impedance is the target load impedance of the non-uniformly matched transmission line; the non-uniformly matched transmission line includes multiple cascaded trapezoidal gradient transmission lines, and the non-uniformly matched transmission line is connected to the rectifier network. A determining unit is used to determine the impedance characteristics of the non-uniformly matched transmission line at the target frequency. The calculation unit is used to calculate the reflection coefficient of the input port of the non-uniformly matched transmission line based on the target load impedance and the impedance characteristics of the non-uniformly matched transmission line. The adjustment unit is used to construct an objective function that minimizes the magnitude of the reflection coefficient at each of the target frequencies, and uses the constraint that the magnitude of the reflection coefficient at each of the target frequencies is less than a preset threshold to adjust the geometric parameters of the non-uniform matching transmission line so that the reflection coefficient at each of the target frequencies meets the preset matching condition, thereby completing the impedance matching of multiple target frequencies.

10. A circuit, characterized in that, include: A cascaded non-uniformly matched transmission line circuit, a rectifier circuit, and a harmonic suppression circuit are provided. The non-uniformly matched transmission line network is used to receive multi-frequency signals and perform impedance matching before outputting them to the rectifier network. After being filtered by the harmonic suppression network, the signals are output to the output load. The non-uniformly matched transmission line network employs the multi-frequency rectification method based on non-uniformly matched transmission lines as described in any one of claims 1 to 8.

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