A miniaturized radio frequency rectifier circuit with a wide power range

Abstract

The invention belongs to the field of radio frequency circuits, and specifically relates to a miniaturized radio frequency rectification circuit with a wide power range; the method comprises: an input end of an impedance matching network is connected to a microwave source, and an output end of the impedance matching network is respectively connected to an input end of a third microstrip line and an input end of a fourth microstrip line; an output end of the third microstrip line is connected to an input end of a second capacitor, and an output end of the fourth microstrip line is connected to an input end of a first capacitor; an output end of the second capacitor is respectively connected to an input end of a second direct-pass filter and a high-power rectification branch, and an output end of the first capacitor is respectively connected to an input end of a first direct-pass filter and a low-power rectification branch; an output end of the first direct-pass filter is connected to a first resistor, and an output end of the second direct-pass filter is connected to a second resistor; the invention has the advantages of a wide power range, high rectification efficiency and small size.

Description

Technical Field

[0001] The present invention belongs to the field of radio frequency circuits, and particularly relates to a miniaturized radio frequency rectifier circuit with a wide power range. Background Art

[0002] Today's wireless communication is accelerating into an era of multi-function, big data, and high-speed transmission, which means that the space around us is filled with electromagnetic / radio frequency energy signals and is increasing at an alarming rate. However, while these electromagnetic energy signals around us complete communication and information energy transfer, they will also cause electromagnetic interference (EMI) to other instrument devices that do not need to receive these signals, forming a kind of electromagnetic pollution. If we look at it from another angle, the surrounding electromagnetic energy provides the prerequisite for radio frequency energy harvesting, and it can also "turn waste into treasure", not only solving the electromagnetic pollution problem, but also providing a new pollution-free energy source. Therefore, radio frequency energy harvesting (REH) has also attracted more and more attention.

[0003] The radio frequency energy harvesting system mainly includes two parts: a receiving antenna and a rectifier circuit. The rectifier circuit includes an impedance matching network, rectifier diodes, a harmonic suppression network, and a load. This technology aims to collect radio frequency energy in the ambient space using a receiving device and convert the radio frequency energy into direct current energy through an energy conversion device to provide energy supply for instrument devices or store it temporarily.

[0004] The rectifier circuit is an important component in a wireless power transfer (WPT) system and a radio frequency energy harvesting (EH) system. The energy harvesting system can collect electromagnetic energy in the surrounding environment to charge some electronic devices that are difficult to wire and replace batteries, such as pipelines and some remote areas. As a key part of the energy harvesting system, the rectifier circuit can convert the collected radio frequency energy into direct current energy and has been widely used in many places, such as solar satellite systems, microwave-powered helicopters, wireless power sensors, biomedical implantable devices, radio frequency identification (RFID), and the application of charging drones. Since the energy power density in the environment is within a very wide power range, it is very necessary to design an efficient radio frequency rectifier circuit with an extended input power range.

[0005] The wide-power rectifier circuit is a core technical issue in the research of radio frequency energy harvesting. The main problems faced now are low rectification efficiency, narrow extended power range, large size, and inapplicability to some miniaturized devices, etc. Therefore, it is of great significance to provide a rectifier circuit with a wide power range and practical value. Summary of the Invention

[0006] Aiming at the deficiencies of the existing technology, the present invention proposes a miniaturized wide - power - range radio - frequency rectification circuit, which includes: a microwave source, an impedance - matching network, a low - power rectification branch, a high - power rectification branch, a first through - filter, a second through - filter, a first capacitor, a second capacitor, a third microstrip line, a fourth microstrip line, a first resistor, and a second resistor; the input end of the impedance - matching network is connected to the microwave source, and the output end of the impedance - matching network is respectively connected to the input end of the third microstrip line and the input end of the fourth microstrip line; the output end of the third microstrip line is connected to the input end of the second capacitor, and the output end of the fourth microstrip line is connected to the input end of the first capacitor; the output end of the second capacitor is respectively connected to the input end of the second through - filter and the high - power rectification branch, and the output end of the first capacitor is respectively connected to the input end of the first through - filter and the low - power rectification branch; the output end of the first through - filter is connected to the first resistor, and the output end of the second through - filter is connected to the second resistor;

[0007] The low - power rectification branch includes a low - power rectification diode and an eighth microstrip line. One end of the eighth microstrip line is connected to the output end of the low - power rectification diode, and the other end is connected to the ground. The input end of the low - power rectification diode is connected to the output end of the first capacitor; the high - power rectification branch includes a high - power rectification diode, a fifth microstrip line, and a sixth microstrip line. One end of the high - power rectification diode is connected to one end of the fifth microstrip line, the other end of the high - power rectification diode is connected to one end of the sixth microstrip line, the other end of the sixth microstrip line is connected to the ground, and the other end of the fifth microstrip line is connected to the output end of the second capacitor.

[0008] Preferably, the impedance - matching network includes a first microstrip line and a second microstrip line; the input end of the first microstrip line is connected to the microwave source, the output end of the first microstrip line is respectively connected to the input end of the third microstrip line, the input end of the fourth microstrip line, and the input end of the second microstrip line, and the output end of the second microstrip line is grounded.

[0009] Preferably, the first through - filter includes a ninth microstrip line and a fourth capacitor; the input end of the ninth microstrip line is connected to the output end of the first capacitor, the output end of the ninth microstrip line is respectively connected to the input end of the fourth capacitor and the first resistor, and the output end of the fourth capacitor is grounded.

[0010] Further, the ninth microstrip line is a quarter - wavelength microstrip line.

[0011] Preferably, the second through - filter includes a seventh microstrip line and a third capacitor; the input end of the seventh microstrip line is connected to the output end of the second capacitor, the output end of the seventh microstrip line is respectively connected to the input end of the third capacitor and the second resistor, and the output end of the third capacitor is grounded.

[0012] Further, the seventh microstrip line is a quarter - wavelength microstrip line.

[0013] Preferably, the eighth microstrip line is an eighth - wavelength microstrip line.

[0014] Preferably, the fifth microstrip line is a quarter-wavelength microstrip line, and the sixth microstrip line is an eighth-wavelength microstrip line.

[0015] The beneficial effects of the present invention are as follows: The present invention adopts a novel rectifier circuit structure, adding another diode parallel structure to the traditional structure with one diode in parallel to form a dual-load branch, which works in the low-power region and the high-power region respectively, improving the rectification efficiency and the input power range. In traditional rectifier circuits, multiple branches are matched separately, increasing the insertion loss and the circuit size. However, the present invention adjusts the real part resistance by adding a section of microstrip line at the front end of each of the two branches, achieving a wide-range matching effect with only one matching at the front end. The present invention adds an eighth-wavelength microstrip line at the end of the parallel branch to cancel the imaginary part resistance of the diode. The eighth-wavelength microstrip line added at the end of the parallel branch also has a certain inhibitory effect on high-order harmonics, can reduce harmonic loss, and improve the rectification efficiency. A simplified rectifier circuit topology structure is realized, reducing the circuit size and achieving the purpose of high-efficiency rectification in a wide power range. Description of the Drawings

[0016] Figure 1 Schematic diagram of the structure of the miniaturized wide-power-range radio frequency rectifier circuit of the present invention;

[0017] Figure 2 Simulation result diagram of the miniaturized wide-power-range radio frequency rectifier circuit of the present invention;

[0018] Figure 3 Simulation result diagram of a rectifier circuit of the prior art. Detailed Embodiments

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0020] The present invention proposes a miniaturized wide-power-range radio frequency rectifier circuit, as Figure 1 shown, the method includes: microwave source MV, impedance matching network, low-power rectifier branch A, high-power rectifier branch B, first through filter, second through filter, first capacitor C 1 , second capacitor C 2 , third microstrip line TL 3 , fourth microstrip line TL 4 , first resistor R L and second resistor R L1; The input end of the impedance matching network is connected to the microwave source MV, and the output end of the impedance matching network is respectively connected to the input ends of the third microstrip line TL 3 and the fourth microstrip line TL 4 ; The output end of the third microstrip line TL 3 is connected to the input end of the second capacitor C 2 , and the output end of the fourth microstrip line TL 4 is connected to the input end of the first capacitor C 1 ; The output end of the second capacitor C 2 is respectively connected to the input end of the second through-filter and the high-power rectification branch B, and the output end of the first capacitor C 1 is respectively connected to the input end of the first through-filter and the low-power rectification branch A; The output end of the first through-filter is connected to the first resistor R L , and the output end of the second through-filter is connected to the second resistor R L1 .

[0021] The low-power rectification branch A includes a low-power rectification diode D 1 and the eighth microstrip line TL 8 , one end of the eighth microstrip line TL 8 is connected to the output end of the low-power rectification diode A, and the other end is connected to the ground. The input end of the low-power rectification diode D 1 is connected to the output end of the first capacitor C 1 ; The high-power rectification branch B includes a high-power rectification diode D 2 , the fifth microstrip line TL 5 and the sixth microstrip line TL 6 , one end of the high-power rectification diode D 2 is connected to one end of the fifth microstrip line TL 5 , the other end of the high-power rectification diode D 2 is connected to one end of the sixth microstrip line TL 6 , the other end of the sixth microstrip line TL 6 is connected to the ground, and the other end of the fifth microstrip line TL 5 is connected to the output end of the second capacitor C 2 . Preferably, the low-power rectification diode D 1 is selected as the HSMS-2860 diode, and the high-power rectification diode D 2 is selected as the HSMS-2862 diode. HSMS2862 is not the traditional connection method of a voltage multiplier diode. The essence adopted is the connection method of internal diode series connection.

[0022] The impedance matching network includes the first microstrip line TL 1 and the second microstrip line TL 2 ; The first microstrip line TL 1The input terminal of 1 is connected to the third microstrip line TL 3 through the output terminal of the first microstrip line TL 4 , the input terminal of the fourth microstrip line TL 2 , and the input terminal of the second microstrip line TL 2 . The output terminal of the second microstrip line TL

[0023] is grounded. One end of the microwave source MV is connected to the input terminal of the first microstrip line TL 1 , and the other end of the microwave source MV is connected to one end of the third resistor Z g . The other end of the third resistor Z g is grounded. Preferably, the resistance value of the third resistor Z g is 50 ohms.

[0024] The first through - filter includes the ninth microstrip line TL 9 and the fourth capacitor C 4 . The input terminal of the ninth microstrip line TL 9 is connected to the output terminal of the first capacitor C 1 . The output terminal of the ninth microstrip line TL 9 is respectively connected to the input terminal of the fourth capacitor C 4 and one end of the first resistor R L . The output terminal of the fourth capacitor C 4 is grounded. Preferably, the ninth microstrip line TL 9 is a quarter - wavelength microstrip line. The other end of the first resistor R L is grounded. Preferably, the resistance value of the first resistor R L is 1200 ohms.

[0025] The second through - filter includes the seventh microstrip line TL 7 and the third capacitor C 3 . The input terminal of the seventh microstrip line TL 7 is connected to the output terminal of the second capacitor C 2 . The output terminal of the seventh microstrip line TL 7 is respectively connected to the input terminal of the third capacitor C 3 and one end of the second resistor R L1 . The output terminal of the third capacitor C 3 is grounded. Preferably, the seventh microstrip line TL 7 is a quarter - wavelength microstrip line. The other end of the second resistor R L1 is grounded. Preferably, the resistance value of the second resistor R L1 is 200 ohms.

[0026] Preferably, the seventh microstrip line is a quarter-wavelength microstrip line, the eighth microstrip line is an eighth-wavelength microstrip line, the fifth microstrip line is a quarter-wavelength microstrip line, and the sixth microstrip line is an eighth-wavelength microstrip line. For the remaining microstrip lines: the first microstrip line, the second microstrip line, the third microstrip line, and the fourth microstrip line, their lengths are not limited and can be adjusted to enable the circuit to achieve the best performance.

[0027] Preferably, the dielectric substrate used in the rectifier circuit of the present invention is Rogers 4003C, the substrate thickness is 0.508 mm, the dielectric constant is 3.55, the conductor thickness is 0.035 mm, and the circuit operating frequency is 5.8 GHz.

[0028] The parallel rectifier circuit is a relatively common form of rectifier circuit. The traditional parallel rectifier circuit includes an impedance matching network, rectifier diodes, a harmonic suppression network, and a load. A matching network is added between the microwave source and the diode to reduce the return loss. The impedance matching network can achieve impedance matching between the source and the diode, reduce the insertion loss, and improve the rectification efficiency. The rectifier diodes are connected in parallel between the impedance matching network and the harmonic suppression network to form a parallel circuit. The output through-filter is composed of a microstrip line (quarter-wavelength microstrip line) and a parallel capacitor (C 3 or C 4 ). It can not only prevent the high-order harmonics from passing through the load, but also play a role in smoothing the DC voltage. A DC-blocking capacitor (C 1 and C 2 ) is added between the microwave source and the diode to prevent DC backflow. The front-end impedance matching network, DC-blocking capacitor, and the back-end through-filter can confine the harmonic energy therein, reflect it back to the diode, and rectify it again through the diode, improving the rectification efficiency. In addition, by adding microstrip lines (TL 3 and TL 4 ) between the impedance matching network and the capacitor, the diode is separated from the connection point, achieving a better layout and avoiding the influence caused by directly connecting the capacitor.

[0029] The present invention makes improvements on the traditional parallel rectifier circuit and selects two parallel branches to work in the low-power region and the high-power region respectively. Suppose there is a non-linear resistor R, and the power P on it depends on the power P applied to it. The present invention adopts the method of connecting two non-linear resistors in parallel. Since the two resistors (R L , R L1 ) have the same voltage, their power is mainly determined by the resistance values of the two resistors. When R2 = R1, it will result in an equal power distribution. Wherein R1 and R2 are respectively the left branch of the two branches (including the third microstrip line TL 3 ) and the right branch of the two branches (including the fourth microstrip line TL 4The resistance of the right branch), and P1 and P2 are the powers of the two branches. The present invention adopts the principle of affecting the branch current by changing the branch resistance and further affecting the branch power distribution. First, two diodes with the same impedance change trend are selected, and they have good rectification effects at low power and high power respectively. To enable the diodes to work in a suitable region, a microstrip line is used in front of the diode in the high-power rectification branch to reverse the diode resistance. The low-power diode presents a relatively low resistance at low power and an increasing resistance trend with power at high power; the high-power diode presents a relatively high resistance at low power and a decreasing resistance trend with power at high power. By changing the resistance, the power distribution is affected, making the power reasonably distributed to achieve the purpose of rectification in a wide power range.

[0030] The present invention is evaluated, and its simulation results are as Figure 2 shown. Among them, Figure (a) is a graph of the rectification efficiency of the miniaturized wide-power-range RF rectifier circuit varying with the input power, Figure (b) is a graph of the S 11 varying with the input power, and S 11 represents the input reflection coefficient, that is, the input return loss. Figure (c) is a graph of the impedance coefficient of the miniaturized wide-power-range RF rectifier circuit varying with the input power. The rectification efficiency of the rectifier circuit is at a frequency of 5.8 GHz. It can be seen from Figure (a) that the input power of the present invention reaches a maximum of 68.6% at 12.9 dBm, and when the input power is in the range of -0.4 dBm to 25.2 dBm, the rectification efficiency is greater than 60%; it can be seen from Figure (c) that when the input power is in the range of 0 dB to 26 dB, the real part resistance is about 50 Ω and the imaginary part resistance is about 0 Ω, showing a good matching effect. It can be seen from Figure (b) that when the input power is in the range of 0 dBm to -30 dB, the reflection coefficient is below -10 dB, and the return loss is very small, which is beneficial to ensuring a relatively high rectification efficiency within the power range; Compared with the simulation results of the 2.45 GHz rectifier circuit of "Single-and Dual-Band RF Rectifiers with Extended Input Power Range Using Automatic Impedance Transforming" published in the journal "IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS" in 2020, as Figure 3 shown. Among them, Figure (d) is a graph of the rectification efficiency of the comparison circuit varying with the input power, and Figure (e) is a graph of the impedance coefficient of the comparison circuit varying with the input power; through comparison, it is found that the rectification range where the rectification efficiency of the present invention is greater than 60% is wider and the size is smaller.

[0031] The present invention makes improvements on the basis of the branch parallel rectifier circuit, simplifies the matching structure, converts from multiple branch multiple matchings to only one matching, and adds a section of microstrip line at the end of the diode branch, which plays the role of reducing the imaginary part resistance value of the diode and filtering out high-order harmonics. Compared with the traditional parallel rectifier circuit, the present invention is superior in terms of wide power range, rectification efficiency and size.

[0032] The above-mentioned embodiments further elaborate in detail the purpose, technical solution and advantages of the present invention. It should be understood that the above-mentioned embodiments are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made to the present invention within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A miniaturized wide power range radio frequency rectifier circuit, characterized in that: include: A microwave source, an impedance matching network, a low-power rectifying branch, a high-power rectifying branch, a first straight-through filter, a second straight-through filter, a first capacitor, a second capacitor, a third microstrip line, a fourth microstrip line, a first resistor and a second resistor; an input end of the impedance matching network is connected to the microwave source, and an output end of the impedance matching network is respectively connected to an input end of the third microstrip line and an input end of the fourth microstrip line; The third microstrip line output end is connected to the second capacitor input end, and the fourth microstrip line output end is connected to the first capacitor input end; The second capacitor output end is connected to the input end and the high-power rectifier branch of the second direct-pass filter respectively, and the first capacitor output end is connected to the input end and the low-power rectifier branch of the first direct-pass filter respectively; the output end of the first direct-pass filter is connected to the first resistor, and the output end of the second direct-pass filter is connected to the second resistor; The low-power rectifying branch includes a low-power rectifying diode and an eighth microstrip line, one end of the eighth microstrip line is connected to the output end of the low-power rectifying diode, and the other end is connected to the ground, and the input end of the low-power rectifying diode is connected to the output end of the first capacitor; the high-power rectifying branch includes a high-power rectifying diode, a fifth microstrip line and a sixth microstrip line, one end of the high-power rectifying diode is connected to one end of the fifth microstrip line, the other end of the high-power rectifying diode is connected to one end of the sixth microstrip line, the other end of the sixth microstrip line is connected to the ground, and the other end of the fifth microstrip line is connected to the output end of the second capacitor.

2. A miniaturized wide power range radio frequency rectifier circuit according to claim 1, characterized in that: The impedance matching network includes a first microstrip line and a second microstrip line; the input end of the first microstrip line is connected to a microwave source, the output end of the first microstrip line is respectively connected to the input end of the third microstrip line, the input end of the fourth microstrip line and the input end of the second microstrip line, and the output end of the second microstrip line is grounded.

3. The miniaturized wide power range radio frequency rectifier circuit according to claim 1, characterized in that: The first straight-pass filter includes a ninth microstrip line and a fourth capacitor; the input end of the ninth microstrip line is connected to the output end of the first capacitor, the output end of the ninth microstrip line is respectively connected to the input end of the fourth capacitor and the first resistor, and the output end of the fourth capacitor is grounded.

4. The miniaturized wide power range radio frequency rectifier circuit according to claim 3, characterized in that: The ninth microstrip line is a quarter-wavelength microstrip line.

5. The miniaturized wide power range radio frequency rectifier circuit according to claim 1, characterized in that: The second pass filter includes a seventh microstrip line and a third capacitor; the input end of the seventh microstrip line is connected to the output end of the second capacitor, the output end of the seventh microstrip line is respectively connected to the input end of the third capacitor and the second resistor, and the output end of the third capacitor is grounded.

6. The miniaturized wide power range radio frequency rectifier circuit according to claim 5, characterized in that: The seventh microstrip line is a quarter-wavelength microstrip line.

7. The miniaturized wide power range radio frequency rectifier circuit according to claim 1, characterized in that: The eighth microstrip line is a one-eighth wavelength microstrip line.

8. The miniaturized wide power range radio frequency rectifier circuit according to claim 1, characterized in that: The fifth microstrip line is a quarter-wavelength microstrip line, and the sixth microstrip line is a eighth-wavelength microstrip line.

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