Ultra-wideband rectifying circuit capable of working to Ku wave band and design method thereof

Abstract

The invention belongs to the technical field of wireless energy transmission and electromagnetic energy collection, and discloses an ultra-wideband rectification circuit capable of working to a Ku wave band and a design method thereof, and the ultra-wideband rectification circuit comprises a top microstrip line structure, a middle dielectric substrate and a bottom metal floor. And the top-layer microstrip structure and the bottom-layer metal floor are respectively positioned on the upper surface and the lower surface of the middle dielectric substrate. The two diodes in the diode topology are directly connected with the direct-current filter capacitor, so that the load impedance is effectively compressed, the harmonic suppression and recovery of low-frequency-band frequency are realized, and the working frequency range of the rectifying circuit is preliminarily widened; a microstrip line filter network is introduced to the rear end of the filter capacitor to suppress high-frequency harmonic waves, so that the working bandwidth of the rectifying circuit is further expanded; according to the invention, ultra-wideband impedance matching is realized through a section of short conical tapered transmission line, and the design process and the debugging process of a rectifying circuit are effectively simplified.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wireless energy transmission and electromagnetic energy collection, and particularly relates to a super-wideband rectifier circuit capable of working up to Ku band and a design method thereof. BACKGROUND

[0002] In recent years, wireless power transmission (WPT) has attracted extensive attention as a key technology to support distributed and battery-free electronic systems, especially in applications such as the Internet of Things, implantable medical devices, and sensor networks. Among them, the rectifier circuit is the core module for realizing efficient conversion of radio frequency signals to direct current power, and its performance has a decisive influence on the overall efficiency of the system. However, the traditional narrowband rectifier has the problem of limited working frequency band, which is difficult to adapt to environments with large frequency changes or wide spectrum energy sources.

[0003] To overcome this limitation, the design of super-wideband rectifiers has gradually become a research hotspot. Such rectifiers can maintain high power conversion efficiency (PCE) in a wider frequency range, significantly improving the adaptability and stability of WPT systems in practical applications. In addition, developing compact and excellent performance super-wideband rectifier circuits not only helps to realize multi-band energy collection and reduce sensitivity to frequency mismatch, but also enhances the overall performance of the system in complex deployment scenarios. Therefore, the design of super-wideband rectifier circuits is of great significance to promote the reliability and scalability of the next generation of wireless power transmission technology.

[0004] However, existing super-wideband rectifier circuits mostly work below the Ku band (12-18 GHz), and with the development of future technology, more and more frequency resources will be applied, and it becomes increasingly important to design super-wideband rectifier circuits covering a wider frequency range.

[0005] Through the above analysis, the problems and defects of the prior art are:

[0006] The traditional narrowband rectifier has the problem of limited working frequency band, which is difficult to adapt to environments with large frequency changes or wide spectrum energy sources. SUMMARY

[0007] In view of the problems existing in the prior art, the present application provides a super-wideband rectifier circuit capable of working up to Ku band and a design method thereof.

[0008] The present application is implemented as follows: a super-wideband rectifier circuit capable of working up to Ku band includes:

[0009] a top microstrip line structure, a middle dielectric substrate, and a bottom metal ground plate;

[0010] The top layer microstrip structure and the bottom layer metal floor are respectively located on the upper surface and the lower surface of the intermediate dielectric substrate; the top layer microstrip structure comprises a radio frequency input port, a broadband impedance matching network, a direct current blocking capacitor, a diode topology structure, a low frequency harmonic suppression and harmonic recovery network, a microstrip line filter network and a direct current output port;

[0011] The radio frequency input port is used for welding a standard 50Ω SMA joint to input a radio frequency signal into the broadband impedance matching network;

[0012] The broadband impedance matching network is used for realizing optimal matching of input impedance, thereby improving transmission efficiency of radio frequency energy to the subsequent circuit;

[0013] The direct current blocking capacitor is used for isolating direct current components generated by the diode, preventing the direct current components from flowing back to the radio frequency signal source, and allowing the radio frequency signal to be effectively transmitted to the rectifier circuit;

[0014] The diode topology structure is used for rectifying the input radio frequency signal to generate a stable direct current output;

[0015] The low frequency harmonic suppression and harmonic recovery network is used for filtering low frequency harmonic signals output by the diode, and simultaneously realizing re-rectification of low frequency fundamental wave and harmonic energy, thereby improving overall energy conversion efficiency;

[0016] The microstrip line filter network is used for enhancing the suppression ability of high frequency harmonics, thereby further expanding the working bandwidth of the rectifier circuit;

[0017] The direct current output port is used for outputting the rectified direct current energy and connecting the subsequent load circuit.

[0018] Further, the radio frequency input port is a microstrip line with a characteristic impedance of 50Ω.

[0019] Further, the broadband impedance matching network is a tapered transmission line.

[0020] Further, the direct current blocking capacitor is a high frequency capacitor 1.

[0021] Further, the diode topology structure comprises a diode 1 and a diode 2.

[0022] Further, the low frequency harmonic suppression and harmonic recovery network comprises a parallel capacitor 2, a parallel capacitor 3 and a microstrip line.

[0023] Further, the microstrip line filter network is a fan-shaped open stub.

[0024] Further, the radio frequency input port is connected with a wideband impedance matching network; the wideband impedance matching network is connected with a high-frequency capacitor 1; one end of the high-frequency capacitor 1 is connected with the wideband impedance matching network, and the other end is connected with the anode of a diode 1 and the cathode of a diode 2; the anode of the diode 1 is connected with the high-frequency capacitor 1 and the cathode of the diode 2, and the cathode is connected with a parallel capacitor 2 and a parallel capacitor 3; the cathode of the diode 2 is connected with the high-frequency capacitor 1 and the anode of the diode 2, and the anode is connected with a bottom metal floor through a metallized via, and the anode of the diode 2 is connected with the parallel capacitor 2 and the parallel capacitor 3 through a microstrip line; one end of the parallel capacitor 2 and the parallel capacitor 3 is connected with the cathode of the diode 1 and a microstrip line filter network, and the other end is connected with the bottom metal floor through a metallized via, and connected with the anode of the diode 2 through a microstrip line; one end of a direct current output port is connected with the microstrip line filter network, and the other end is connected with a load.

[0025] In combination with the above technical solutions and the technical problems solved, the technical solutions to be protected by the present application have the following advantages and positive effects:

[0026] In the diode topology, the two diodes are directly connected with the direct current filter capacitor, which not only effectively compresses the load impedance, but also realizes the harmonic suppression and recovery of the low-frequency band, and preliminarily widens the working frequency range of the rectifier circuit; the present application introduces a microstrip line filter network at the rear end of the filter capacitor to suppress high-frequency harmonics, further expanding the working bandwidth of the rectifier circuit; the present application realizes super wideband impedance matching through a short tapered gradual transmission line, effectively simplifying the design process and debugging process of the rectifier circuit, and the present application not only has significant innovation in structural design, but also has better performance than the prior art, providing strong technical support for the realization of the super wideband wireless energy transmission system.

[0027] The super wideband rectifier circuit proposed by the present application can work up to the Ku band (12-18GHz), and is superior to the similar technologies reported in the prior art in terms of absolute bandwidth, relative bandwidth and frequency ratio, has stronger environmental adaptability, and realizes the miniaturization design of the size, significantly reduces the overall cost and volume of the system. It is expected to realize good technical transformation and commercial application value in the fields of wireless energy transmission and Internet of Things.

[0028] The present application proposes a new super wideband circuit design method, which significantly improves the bandwidth performance of the circuit and effectively fills the technical gap in this field at home and abroad.

[0029] The super wideband rectifier circuit proposed by the present application not only realizes the comprehensive coverage of the Sub-6GHz frequency band and the X band, but also can work in the Ku band, while maintaining the simplicity and efficiency of the structure, showing a broad application prospect in the WPT system. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the topology schematic diagram of the ultra-wideband rectifier circuit working to Ku band provided by the embodiment of the present application;

[0031] Figure 2 is the layout of the dimensioned provided by the embodiment of the present application;

[0032] Figure 3 is the curve diagram of the power conversion efficiency changing with the input frequency under different input powers provided by the embodiment of the present application; Figure 1 input impedance Z in the structure in1 trajectory diagram changing with the input frequency;

[0033] Figure 4 is the curve diagram of the power conversion efficiency changing with the input frequency under different input powers provided by the embodiment of the present application; Figure 1 input impedance Z in the structure in trajectory diagram changing with the input frequency;

[0034] Figure 5 is the curve diagram of the power conversion efficiency changing with the input frequency under different input powers provided by the embodiment of the present application;

[0035] Figure 6 is the measured curve diagram of the power conversion efficiency changing with the load impedance under different input powers and input frequencies provided by the embodiment of the present application;

[0036] Figure 7 is the measured curve diagram of the power conversion efficiency changing with the input power under different input frequencies provided by the embodiment of the present application;

[0037] In the figure: 1, high-frequency capacitor 1; 2, diode 1; 3, diode 2; 4, high-frequency capacitor 2; 5, high-frequency capacitor 3; 101, wideband impedance matching network; 102, low-frequency harmonic suppression and harmonic recovery network; 103, microstrip line filtering network. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0039] In this embodiment, an ultra-wideband rectifier circuit capable of operating up to the Ku band and its design method are described, comprising a top-layer microstrip line structure, an intermediate dielectric substrate, and a bottom-layer metal ground plane. The top-layer microstrip structure and the bottom-layer metal ground plane are located on the upper and lower surfaces of the intermediate dielectric substrate, respectively. The top-layer microstrip structure includes an RF input port, a wideband impedance matching network, a DC blocking capacitor, a diode topology, a low-frequency harmonic suppression and harmonic recovery network, a microstrip line filter network, and a DC output port.

[0040] like Figure 1 As shown in the circuit topology schematic, the designed top-level microstrip line structure includes an RF input port, a broadband impedance matching network 101, a high-frequency capacitor 1, diodes 1 and 2, a high-frequency capacitor 2 and 3, a low-frequency harmonic suppression and harmonic recovery network 102, a microstrip line filter network 103, and a DC load R. L .

[0041] The radio frequency input port is a microstrip line with a characteristic impedance of 50Ω, used to solder a standard 50Ω SMA connector to input the radio frequency signal into the broadband impedance matching network.

[0042] The broadband impedance matching network 101 is a short tapered transmission line TL1 used to achieve impedance matching over a wide range, so that as much energy as possible can be transferred to the diode.

[0043] The high-frequency capacitor 1 is a high-frequency lumped capacitor used to allow the input radio frequency signal to pass through, while preventing the DC current generated by the diode from flowing into the radio frequency signal source;

[0044] Diode 1 and diode 2 are Schottky diodes used to convert radio frequency energy into DC energy;

[0045] The low-frequency harmonic suppression and harmonic recovery network 102 includes a high-frequency capacitor 2, a high-frequency capacitor 3, and a microstrip line TL2. Both high-frequency capacitor 2 and high-frequency capacitor 3 are high-frequency lumped capacitors used to filter out the output noise of the Schottky diode and recover the fundamental and higher harmonics. The microstrip line TL2 is used to connect the anode of the diode 2 and the high-frequency capacitor 1 to the high-frequency capacitor 3.

[0046] The microstrip line filter network includes three fan-shaped open-circuit stubs TL3, TL4 and TL5;

[0047] The DC output port is used to connect to the downstream load R. L .

[0048] The radio frequency input port is connected with a short taper gradual change transmission line TL1; the short taper gradual change transmission line TL1 is connected with a high-frequency capacitor 1; one end of the high-frequency capacitor 1 is connected with the short taper gradual change transmission line TL1, and the other end is connected with the anode of a diode 1 and the cathode of a diode 2 respectively; the anode of the diode 1 is connected with the high-frequency capacitor 1 and the cathode of the diode 2 respectively, and the cathode is connected with a parallel capacitor 2 and a parallel capacitor 3; the cathode of the diode 2 is connected with the high-frequency capacitor 1 and the anode of the diode 2 respectively, and the anode is connected with a bottom metal floor through a metallized via, and meanwhile the anode of the diode 2 is connected with the parallel capacitor 2 and the parallel capacitor 3 through a microstrip line TL2; one end of the parallel capacitor 2 and the parallel capacitor 3 is connected with the cathode of the diode 1 and a microstrip line filter network, and the other end is connected with the bottom metal floor through a metallized via, and meanwhile the other end is connected with the anode of the diode 2 through the microstrip line TL2; one end of the microstrip line filter network is connected with the parallel capacitor 2 and the parallel capacitor 3, and the other end is connected with a direct current output port; one end of the direct current output port is connected with the microstrip line filter network, and the other end is connected with a load R L .

[0049] In order to further illustrate the feasibility of the design method herein, actual processing verification is carried out. Rogers 5880 material (dielectric constant is 2.2, loss tangent is 0.0009) is used as a dielectric substrate, the thickness of the dielectric substrate is 0.254 mm, and the thickness of the top layer microstrip structure and the bottom layer metal floor is 0.035 mm.

[0050] As shown in Figure 2 , the layout and specific size mark of the application embodiment, the radio frequency input port is a microstrip line with a characteristic impedance of 50Ω, the wideband impedance matching network is a short taper gradual change transmission line, the capacitors are CBR04C101F3GAC (the capacitance is 100pF), the microstrip line filter network is designed by a fan-shaped branch, and the diodes are MA4E1317. The overall size of the rectifier circuit is 24mm*9.54mm.

[0051] The radio frequency input port is connected with a short taper gradual change transmission line TL1; the short taper gradual change transmission line TL1 is connected with a high-frequency capacitor 1; one end of the high-frequency capacitor 1 is connected with the short taper gradual change transmission line TL1, and the other end is connected with the anode of a diode 1 and the cathode of a diode 2 respectively; the anode of the diode 1 is connected with the high-frequency capacitor 1 and the cathode of the diode 2 respectively, and the cathode is connected with parallel capacitors 2 and 3; the cathode of the diode 2 is connected with the high-frequency capacitor 1 and the anode of the diode 2 respectively, and the anode is connected with a bottom metal floor through a metallized via, and meanwhile the anode of the diode 2 is connected with the parallel capacitors 2 and 3 through a microstrip line TL2; one end of the parallel capacitors 2 and 3 is connected with the cathode of the diode 1 and a fan-shaped open stub TL3 in a microstrip line filter network, and the other end is connected with the bottom metal floor through a metallized via and connected with the anode of the diode 2 through the microstrip line TL2; one end of the microstrip line filter network is connected with the parallel capacitors 2 and 3, and the other end is connected with a direct current output port, wherein the fan-shaped open stub TL3 is connected with a fan-shaped open stub TL4, and the fan-shaped open stub TL4 is connected with a fan-shaped open stub TL5; one end of the direct current output port is connected with the fan-shaped open stub TL5 in the microstrip line filter network, and the other end is connected with a load R L

[0052] After the radio frequency excitation is injected by the 50Ω input microstrip line, it first enters the short taper gradual change transmission line TL1. The gradual change line couples most of the incident power to the node C (the high-frequency capacitor 1 and the diode anode / cathode confluence) by continuously adjusting the characteristic impedance, so that the equivalent admittance remains conjugate with the equivalent impedance of the diode in the working frequency band. The high-frequency capacitor 1 only provides a low impedance path for radio frequency and a high impedance for direct current, which not only maintains the lossless transmission of radio frequency energy, but also blocks the direct current component generated by the later-stage rectification from backflowing to the signal source, ensuring stable source end bias.

[0053] At the node C, the signal is added to the anode of the diode 1 and the cathode of the diode 2, forming a reverse symmetric Schottky half-bridge. During the positive half cycle of the alternating voltage, the diode 1 is turned on and the diode 2 is turned off, and the roles are interchanged during the negative half cycle, completing half-wave charge extraction; the center node of the bridge arm is directly grounded through a metallized via, forming a low-inductance backflow loop. The rectified low-frequency fundamental and high-order harmonic currents are introduced into the harmonic suppression / recycling network composed of the parallel high-frequency capacitors 2 and 3 and the microstrip line TL2: the parallel capacitors produce capacitive traps, and TL2 provides distributed inductance, forming a tunable series-parallel composite resonance, so that the harmonic energy is again folded back and rectified, improving conversion efficiency, and achieving deep attenuation of high-amplitude spurs.

[0054] ​The remaining medium-high frequency harmonics enter the microstrip filter network composed of three segments of fan-shaped open-circuit stubs TL3-TL5 along the main stem. Each segment is open-circuited at a specified resonant frequency, equivalent to a parallel bandstop, so that the high frequency and its harmonic components are gradually absorbed into the substrate and scattered to the ground plane, achieving wideband suppression. The filtered and purified direct current is fed to the load R through the output port L The load-side backflow is closed through the underlying metal floor, and the low-loss characteristics of the substrate medium ensure the thermal stability and long-term reliability of direct current / low frequency energy transmission. The entire workflow from input impedance integration, nonlinear rectification, harmonic reuse to wideband filtering closed loop forms a low-reflection, high-efficiency energy conversion chain.

[0055] As shown in Figure 3 and Figure 4 , the input impedance before and after the addition of the short tapered gradual transmission line TL1 is simulated respectively to verify the performance of the short tapered gradual transmission line TL1. The results show that after the addition of the tapered transmission line TL1, the input impedance of the rectifier circuit converges at about 50Ω, showing good impedance matching ability.

[0056] The rectifier circuit layout is prepared and tested, and the simulation and measured results are shown in Figure 5 , Figure 6 and Figure 7 . The measured results show that under an input power of 22-23dBm, the power conversion efficiency of the rectifier circuit is greater than 50% in the frequency range of 0.03-16.5GHz, the absolute bandwidth is 16.47GHz, the fractional bandwidth is 199.3%, and the frequency ratio is 550; under the condition of a direct current load of 200Ω, an input frequency of 5.8GHz, and an input power of 24dBm, the peak efficiency reaches 70.71%. It can be seen that the ultra-wideband rectifier circuit in the embodiment can cover the Sub-6GHz frequency band, the X-band and the Ku-band, and has a wide application prospect in WPT.

[0057] In the ultra-wideband energy harvesting scenario, the antenna-rectifier link often causes the conversion efficiency to drop sharply due to the dramatic fluctuation of the input standing wave ratio with frequency. To solve this bottleneck, this scheme introduces a multi-stage tapered gradual transmission line into the microstrip layer, continuously tunes the equivalent inductance-capacitance distributed parameters, and maintains the port reflection coefficient below -15dB in the range of 0.03-16.5GHz, thereby integrating the wideband impedance into a single matching domain, fundamentally solving the problem of limited bandwidth of traditional segmented cascaded networks.

[0058] The DC blocking structure adopts a sheet U-HiQ high-frequency capacitor which is distributed in parallel with a signal main stem, cooperates with an embedded stepped via hole ground loop, and realizes full-path isolation of a radio frequency mode and a DC mode in the same plane. The layout forms a π-type network of the capacitor-via hole-ground plane to deeply attenuate a 10 kHz-500 MHz flat section, effectively shields the backflow DC after diode rectification, and avoids bias drift on a front-stage radio frequency source, which is a process-level isolation method which is not used in existing ultra-wideband rectifiers.

[0059] The diode topology adopts a reverse symmetric half-bridge, and a local resonance sector branch is introduced on the cathode side. The branch presents a virtual ground short-circuit load for odd harmonics and a λ / 4 open circuit for even harmonics, forms a "differential mode passivation-common mode block" coupling effect; cooperates with the coplanar parasitic capacitance between the double diodes, so that the harmonic compression ratio of the rectification node is improved by 6 dB, and the problem of high-order harmonic accumulation backflow in the microstrip plane is solved.

[0060] The low-frequency harmonic suppression and recovery network is composed of a parallel C2 / C3-L microstrip section, and by setting a non-linear voltage-controlled capacitance film on the parallel branch, the fundamental wave and its harmonics can be returned and rectified into DC. The "suppression-recovery" dual-function module enables the energy utilization rate to be increased by about 12% compared with the traditional filtering scheme, which embodies the original design idea from the spectral domain power management perspective.

[0061] Embodiment one is for Internet of Things terminals. In 0.7-10 GHz, Rogers RO4350B substrate (substrate thickness is 0.254 mm, ε r =3.66, tan δ=0.004) is selected. The wideband matching unit adopts a 2.5 mm long tapered microstrip gradual line; the DC blocking capacitor is a 100 pF U-HiQ 0402 package; the diode topology uses a MA4E1310 reverse parallel structure. The low-frequency harmonic suppression network is composed of a 47 pF parallel capacitor and a 0.9 mm microstrip section to form a trap-recovery loop. The prototype can output a rectification efficiency of 55%-70% in the full bandwidth under a 23 dBm incident power, and the size is 12 mm x 12 mm.

[0062] This embodiment maintains the same topology framework, and by adjusting the substrate dielectric constant, the tapered line length, the diode model and the parallel capacitance value, the adaptation to different frequency bands and power levels is realized, highlighting high efficiency, small size, suitability for distributed sensing nodes, and verifying the scalability of the structure in the dynamic frequency variation scenario.

[0063] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement made by any person skilled in the art within the technical scope disclosed by the present application shall be covered within the protection scope of the present application.

Claims

1. An ultrawideband rectifier circuit capable of operating up to the Ku band, comprising a top microstrip line structure, an intermediate dielectric substrate, and a bottom metal ground plane; The top microstrip line structure is located on the upper surface of the intermediate dielectric substrate, and the bottom metal ground plane is located on the lower surface of the intermediate dielectric substrate. The top-level microstrip line structure consists of an RF input port, a broadband impedance matching network, a DC blocking capacitor, a diode topology, a low-frequency harmonic suppression and harmonic recovery network, a microstrip line filter network, and a DC output port. The RF input port is connected to the broadband impedance matching network, the broadband impedance matching network is connected to the DC blocking capacitor, the DC blocking capacitor is connected to the diode topology, the diode topology is connected to the low-frequency harmonic suppression and harmonic recovery network, the low-frequency harmonic suppression and harmonic recovery network is connected to the microstrip line filter network, and the microstrip line filter network is connected to the DC output port.

2. The rectifier circuit according to claim 1, characterized in that, The RF input port is a microstrip line with a characteristic impedance of 50Ω.

3. The rectifier circuit according to claim 1, characterized in that, The broadband impedance matching network is a tapered transmission line.

4. The rectifier circuit according to claim 1, characterized in that, DC blocking capacitors are high-frequency capacitors.

5. The rectifier circuit according to claim 1, characterized in that, The diode topology consists of a first diode and a second diode; The anode of the first diode is connected to a broadband impedance matching network via a DC blocking capacitor, and the cathode of the first diode is connected to a low-frequency harmonic suppression and harmonic recovery network. The cathode of the second diode is connected to a DC blocking capacitor, and the anode of the second diode is connected to the underlying metal ground plane via a metallized via, and connected to a low-frequency harmonic suppression and harmonic recovery network via a microstrip line.

6. The rectifier circuit according to any one of claims 1 or 5, characterized in that, The low-frequency harmonic suppression and harmonic recovery network consists of parallel capacitor two, parallel capacitor three, and a microstrip line segment. One end of parallel capacitor two and parallel capacitor three is connected to the anode of the second diode via the microstrip line segment and is connected to the bottom metal ground plane via a metallized via. The other end is connected to the cathode of the first diode.

7. The rectifier circuit according to claim 1, characterized in that, The microstrip line filter network has a fan-shaped open-circuit stub structure.

8. A rectifier module, comprising the rectifier circuit as described in any one of claims 1-7, a coaxial connector soldered to the RF input port, and a load resistor connected to the DC output port.

9. A radio frequency energy harvesting device, comprising an antenna, a coaxial transmission line, and a rectifier circuit as described in any one of claims 1-7, wherein the antenna is connected to a radio frequency input port via the coaxial transmission line, and the DC output port is connected to an energy storage component.

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