CN107294503B - An Impedance Automatic Tuning System with Real-time Monitoring and Automatic Compensation - Google Patents

Abstract

The invention relates to the technical field of automatic impedance tuning of broadband high-power radio frequency amplifiers, in particular to a broadband high-frequency power source that can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time to realize automatic compensation function. An automatic impedance tuning system capable of real-time monitoring and automatic compensation for solving the detuning of the front-stage impedance of the tetrode; it mainly includes a control unit and a high-frequency power source connected through an impedance resonance matching network, and the present invention is mainly an automatic The tracking impedance tuning technology, more specifically, can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the pre-amplifier in real time, and automatically compensate the impedance change caused by the tetrode grid capacitor Ckg1 in a wide frequency band. The input impedance of the tetrode grid can always be guaranteed to be in a resonant matching state in the entire broadband operating range, so that the working efficiency and overall performance of the high-power tetrode amplifier can be greatly improved.

Description

An Impedance Automatic Tuning System with Real-time Monitoring and Automatic Compensation

technical field

The invention relates to the technical field of automatic impedance tuning of broadband high-power radio frequency amplifiers, in particular to a broadband high-frequency power source that can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time to realize automatic compensation function. An automatic impedance tuning system capable of real-time monitoring and automatic compensation for solving the detuning of the front stage impedance of the tetrode.

Background technique

High-frequency and high-power are required in the high-frequency power sources of certain particle accelerators and high-power short-wave transmitters for microwave communication, or in proton and heavy ion accelerators in the field of basic scientific experimental research, as well as space radiation effects and accelerator-driven clean nuclear energy devices Electron tetrode amplifiers work in a wide frequency range. For example, ferrite-loaded high-frequency acceleration chambers used in proton and heavy ion synchrotrons and medical accelerators for cancer treatment require high-frequency power sources with high-frequency power sources. In order to ensure the normal and reliable operation of the high-frequency power source in a wide frequency band, the impedance matching of all levels of the power amplifier is very important. The gate input impedance will change with the frequency, causing the front-stage impedance of the tetrode to be detuned, resulting in an increase in the reflected power of the pre-amplifier, affecting the power output of the power source and causing the overall performance of the power source to deteriorate; in order to compensate for the The detuning caused by this is usually adopted by adding a passive impedance matching network between the pre-amplifier and the tetrode amplifier, which is feasible for power amplifiers with narrow-band operating frequencies, but due to the The bandwidth of the device is limited, and the non-adjustable impedance matching network cannot meet the requirements of broadband matching, so it is not suitable for amplifiers that operate in sweeping frequency bands. Although the Chinese patent number is 201410300942.1, and the patent name is a method for tuning a broadband high-power radio frequency transmitter, a method for tuning a broadband high-power radio frequency transmitter is disclosed, which involves an automatic tuning technology, that is, in a wideband high-power radio frequency transmitter When the power RF transmitter is running with short pulses, the data acquisition system is used to monitor the working status of the tube amplifiers at all levels of the transmitter, and by analyzing the collected parameters of the tube to feedback and adjust each tuning element of the transmitter, so that the transmitter tube amplifier achieves the best performance. Working state and maximum power output, although this method can scientifically and accurately reflect the working state of the transmitter tube amplifier in the form of a data chart, it cannot perform real-time monitoring and automatic impedance tuning.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies in the prior art, the present invention aims to provide a high-power short-wave transmitter used in high-frequency power sources for particle accelerators and microwave communications, or proton and heavy ion accelerators in the field of basic scientific experimental research, and Space radiation effect and accelerator-driven clean nuclear energy device for real-time monitoring of the detuning angle of the output impedance of the preamplifier to control and adjust the parameters of the matching network for automatic compensation to solve the detuning of the tetrode preamplifier. And auto-compensated impedance auto-tuning system.

In order to achieve the above-mentioned purpose, the technical scheme adopted in the present invention is: a kind of impedance automatic tuning system that can be monitored in real time and automatically compensated, and the impedance automatic tuning system mainly includes a control unit and a high-frequency power source connected through an impedance resonance matching network. , wherein the control unit is connected to the front end of the impedance resonance matching network, and the high frequency power source is connected to the back end of the impedance resonance matching network.

The high-frequency power source mainly includes a pre-amplifier, a tetrode amplifier and a high-frequency load. The pre-amplifier is connected to the tetrode amplifier through an impedance resonance matching network to provide input signal drive for the tetrode. The grid cathode capacitor Ckg1 is connected with the grid input impedance to form the input impedance of the tetrode amplifier, is connected with the impedance resonance matching network, and the high frequency load is connected with the anode output of the tetrode.

The impedance resonance matching network is an adjustable inductance network made of ferrite surrounding, including four ferrite surrounding inductors, the ferrite ring is wound with windings, and the four ferrite The body ring shares a 120T bias coil. By changing the current in the bias coil on the ferrite ring, the strength of the bias magnetic field in the ferrite ring can be adjusted to change the magnetic permeability of the ferrite ring. As a result, the inductance value formed by the ferrite ring and the winding changes, so the inductance value of the matching network can be adjusted by controlling the bias current, and the detuning of the gate input impedance caused by the frequency change can be neutralized and compensated. Automatic tuning matching of gate impedance.

The control unit mainly includes a phase detector, a controller and a bias power supply. The phase detector is used to detect the phase difference of the output impedance of the pre-amplifier of the high-frequency power source. The phase detector is located at the front end of the controller and controls the phase difference. The output of the controller is connected to the bias power supply, and the controller function is realized by FPGA programming. In order to improve the anti-interference ability of the remote transmission of the control signal, the optical cable digital communication is used between the controller and the bias power supply; the bias power supply and the impedance match The bias coils of the network are connected, and the output current of the bias current source is controlled by comparing the phase difference between the input and output signals of the preamplifier to adjust the inductance in the matching network and compensate the phase difference.

Each of the ferrite rings is a pair, and the coils on the two ferrite rings are wound in anti-parallel, so that the induced voltages generated by the bias current in the inductor coils cancel each other out.

Each ferrite ring is wound with 6 turns of windings, and the number of turns depends on the inductance requirement of the matching network.

Windings with the same number of turns are wound around each of the ferrite rings.

The output current of the bias power supply is determined by the tuning range of the network, and the range is between 0 and 10A.

The impedance resonance matching network has an impedance transformation function, which transforms the large-value output impedance of the pre-amplifier into a small-value gate input impedance to ensure impedance matching between the two-stage amplifiers.

The impedance resonance matching network has a 4:1 impedance transformation function, which transforms the 800Ω output impedance of the pre-amplifier into a 200Ω gate input impedance.

The controller is a PID controller.

The impedance automatic tuning system can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the preamplifier in real time, and automatically compensate the impedance change caused by the tetrode grid capacitor Ckg1 in a wide frequency band.

The beneficial effects of the present invention are as follows: the present invention is mainly an automatic tracking impedance tuning technology, and more specifically, the parameters of the matching network can be controlled and adjusted by monitoring the detuning angle of the output impedance of the preamplifier in real time, and the tetrode can be automatically compensated. The impedance change caused by the gate capacitor Ckg1 in the wide frequency band makes it possible to always ensure that the input impedance of the tetrode grid is in a resonant matching state in the entire wide frequency band operating range, which can greatly improve the working efficiency and efficiency of the high-power tetrode amplifier. Overall performance.

Description of drawings

FIG. 1 is a schematic diagram of the logical connection of the present invention.

FIG. 2 is a schematic diagram of an impedance resonance matching network in the present invention.

Detailed ways

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings:

As shown in Figure 1-2, an automatic impedance tuning system that can monitor and automatically compensate in real time, the automatic impedance tuning system mainly includes a control unit and a high-frequency power source connected through an impedance resonance matching network, wherein the control unit is connected to At the front end of the impedance resonance matching network, the high frequency power source is connected at the back end of the impedance resonance matching network.

The high-frequency power source mainly includes a pre-amplifier, a tetrode amplifier and a high-frequency load. The pre-amplifier is connected to the tetrode amplifier through an impedance resonance matching network to provide input signal drive for the tetrode. The grid cathode capacitor Ckg1 is connected with the grid input impedance to form the input impedance of the tetrode amplifier, is connected with the impedance resonance matching network, and the high frequency load is connected with the anode output of the tetrode.

The impedance resonance matching network is an adjustable inductance network surrounded by ferrite. The impedance resonance matching network has the function of impedance transformation, which transforms the large output impedance of the pre-amplifier into the gate input impedance of small value, ensuring that Impedance matching between the two-stage amplifiers; the impedance resonance matching network has a 4:1 impedance transformation function, which transforms the 800Ω output impedance of the pre-amplifier into a 200Ω gate input impedance.

It includes an inductor made of four ferrite rings, each ferrite ring is wound with the same number of turns, and the four ferrite rings share a 120T bias coil, more specifically, each Each ferrite ring is wound with 6 turns of windings, and the number of turns depends on the inductance requirement of the matching network; each of the two ferrite rings is a pair, and the coils on the two ferrite rings The inverse parallel winding is adopted, so that the induced voltages generated by the bias current in the inductance coil cancel each other; by changing the current in the bias coil on the ferrite ring, the bias magnetic field strength in the ferrite ring can be adjusted, The magnetic permeability of the ferrite ring is changed, resulting in the change of the inductance value formed by the ferrite ring and the winding. Therefore, the inductance value of the matching network can be adjusted by controlling the bias current, and the gate input caused by the frequency change can be adjusted. The detuning of the impedance is neutralized and compensated, thereby realizing the automatic tuning and matching of the gate impedance.

The control unit mainly includes a phase detector, a controller and a bias power supply. The phase detector is used to detect the phase difference of the output impedance of the pre-amplifier of the high-frequency power source. The phase detector is located at the front end of the controller and controls the phase difference. The controller is a PID controller, the output of the controller is connected to the bias power supply, the output current of the bias power supply is determined by the tuning range of the network, and the range is between 0~10A; the controller function is realized by FPGA programming, in order to improve the The anti-interference ability of the control signal remote transmission, the optical cable digital communication is used between the controller and the bias power supply; the bias power supply is connected with the bias coil of the impedance matching network, and the control is performed by comparing the phase difference between the input and output signals of the pre-amplifier The output current of the bias current source can adjust the inductance in the matching network and compensate the phase difference; the impedance automatic tuning system can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the pre-amplifier in real time. Compensate for the impedance change caused by the tetrode grid capacitance Ckg1 in a wide frequency band.

The present invention can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the pre-amplifier in real time, and automatically compensate the impedance change caused by the tetrode grid capacitor Ckg1 in a wide frequency band. The specific working principle is as follows:

First of all, the impedance resonance matching network in the present invention adopts an adjustable inductance network surrounded by ferrite. By changing the current in the bias coil on the ferrite ring, the intensity of the bias magnetic field in the ferrite ring is adjusted, The magnetic permeability of the ferrite ring is changed, resulting in the change of the inductance value formed by the ferrite ring and the winding. Therefore, the inductance value of the matching network can be adjusted by controlling the bias current, and the gate input caused by the frequency change can be adjusted. The detuning of the impedance is neutralized and compensated, thereby realizing the automatic tuning and matching of the gate impedance.

At the same time, the impedance resonance matching network is composed of two pairs of inductors surrounded by 4 ferrites, as shown in Figure 2. Each ferrite ring is wound with 6 turns of windings, and the number of turns depends on the inductance of the matching network. Requirement, 4 ferrite rings share a bias coil (120T), the output current of the bias power supply is determined by the tuning range of the network, the output current range is 0~10A, in order to offset the influence of the bias magnetic field on the RF circuit, Each two ferrite rings is a pair, and the coils on the two rings are wound in anti-parallel, so that the induced voltages generated by the bias current in the inductance coils cancel each other out and do not affect the high-frequency circuit.

In order to match the impedance between the preamplifier and the final tetrode amplifier, the impedance resonance matching network has a 4:1 impedance transformation function in addition to the tuning function, which can transform the 800Ω output impedance of the preamplifier into 200Ω. The input impedance of the gate is guaranteed to match the impedance between the two amplifiers. Since the output load impedance of the pre-amplifier is mainly composed of the input resistance of the tetrode amplifier, the tetrode gate-cathode capacitor Ckg1 and the impedance of the impedance resonance matching network, when it is ensured that the input and output voltages of the pre-amplifier are in phase, that is, When the phase difference tends to zero, the output impedance of the pre-amplifier is pure resistance, and the grid of the valve is in the best tuning state.

Once the input impedance of the tetrode gate cathode capacitor Ckg1 changes due to frequency changes or other conditions, causing the gate impedance of the valve to be detuned, a phase difference will be generated between the input and output voltage of the pre-amplifier. The phase detector detects the phase difference between the input and output signals of the pre-amplifier, and after processing by the PID controller, it controls the output current of the bias current source. The controller will control the iron according to the phase difference signal detected by the phase detector. The bias current of the oxygen ring, since the bias power supply is connected to the bias coil of the impedance resonance matching network, the change of the current in the coil will change the inductance in the impedance resonance matching network, thereby compensating the capacitive reactance component in the impedance , to make the phase difference tend to zero, to ensure that the input impedance of the quaternary gate is always in a resonant state, that is, a pure resistance state. The function of the controller in the present invention is realized by FPGA programming. In order to improve the anti-interference ability of remote transmission of control signals, Optical cable digital communication is used between the controller and the bias power supply; thus, the work efficiency and overall performance of the high-power tetrode amplifier can be greatly improved.

To sum up, as an automatic tracking impedance tuning technology, the present invention can control and adjust the parameters of the matching network by monitoring the detuning angle of the output impedance of the pre-amplifier in real time, and automatically compensate the tetrode grid capacitance Ckg1 in the broadband frequency. The impedance change caused by the band makes it possible to always ensure that the input impedance of the tetrode amplifier is in a resonant matching state in the entire wide-band working range, thereby greatly improving the working efficiency and overall performance of the high-power tetrode amplifier.

The above are only preferred embodiments of the present invention, and do not limit the technical scope of the present invention. Those skilled in the industry can make some deformations and modifications under the inspiration of this technical solution. Any modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (9)

1. an impedance auto-tuning system capable of real-time monitoring and automatic compensation, is characterized in that: the described impedance auto-tuning system mainly comprises a control unit and a high-frequency power source connected by an impedance resonance matching network, wherein the control unit is connected in the impedance The front end of the resonance matching network, and the high frequency power source is connected to the back end of the impedance resonance matching network; The high-frequency power source mainly includes a pre-amplifier, a tetrode amplifier and a high-frequency load. The pre-amplifier is connected to the tetrode amplifier through an impedance resonance matching network to provide input signal drive for the tetrode. The gate cathode capacitor Ckg1 is connected with the gate input impedance to form the input impedance of the tetrode amplifier, and is connected with the impedance resonance matching network, and the high-frequency load is connected with the anode output of the tetrode; The impedance resonance matching network is an adjustable inductance network made of ferrite surrounding, including four ferrite surrounding inductors, the ferrite ring is wound with windings, and the four ferrite The body ring shares a 120T bias coil. By changing the current in the bias coil on the ferrite ring, the strength of the bias magnetic field in the ferrite ring can be adjusted to change the magnetic permeability of the ferrite ring. As a result, the inductance value formed by the ferrite ring and the winding changes, so the inductance value of the matching network can be adjusted by controlling the bias current, and the detuning of the gate input impedance caused by the frequency change can be neutralized and compensated. Automatic tuning and matching of gate impedance; The control unit mainly includes a phase detector, a controller and a bias power supply. The phase detector is used to detect the phase difference of the output impedance of the pre-amplifier of the high-frequency power source. The phase detector is located at the front end of the controller and controls the phase difference. The output of the controller is connected to the bias power supply, and the controller function is realized by FPGA programming. In order to improve the anti-interference ability of the remote transmission of the control signal, the optical cable digital communication is used between the controller and the bias power supply; the bias power supply and the impedance match The bias coils of the network are connected, and the output current of the bias current source is controlled by comparing the phase difference between the input and output signals of the preamplifier to adjust the inductance in the matching network and compensate the phase difference. 2. A kind of impedance automatic tuning system capable of real-time monitoring and automatic compensation according to claim 1, it is characterized in that: every two described ferrite rings are a pair, and the two ferrite rings on the The coils are wound in anti-parallel, so that the induced voltages generated by the bias current in the inductor coils cancel each other out. 3. a kind of impedance auto-tuning system capable of real-time monitoring and automatic compensation according to claim 1, is characterized in that: each ferrite ring is wound with 6 turns of windings, and the number of turns of the windings depends on the matching network to the inductance quantity demand. 4. The impedance automatic tuning system capable of real-time monitoring and automatic compensation according to any one of claims 1-3, wherein each of the ferrite rings is wound with windings with the same number of turns. 5. a kind of impedance auto-tuning system capable of real-time monitoring and automatic compensation according to claim 1, is characterized in that: the output current of the described bias power supply is determined by the tuning range of the network, and the range is between 0～10A . 6. A kind of impedance automatic tuning system capable of real-time monitoring and automatic compensation according to claim 1, it is characterized in that: described impedance resonance matching network has impedance transformation function, and the large value output impedance of pre-amplifier is transformed into A small value of gate input impedance ensures impedance matching between the two amplifiers. 7. The impedance auto-tuning system capable of real-time monitoring and automatic compensation according to claim 6, wherein the impedance resonance matching network has a 4:1 impedance transformation function, and outputs the 800Ω output of the preamplifier. The impedance was transformed to a 200Ω gate input impedance. 8 . The impedance automatic tuning system capable of real-time monitoring and automatic compensation according to claim 1 , wherein the controller is a PID controller. 9 . 9. The impedance auto-tuning system capable of real-time monitoring and automatic compensation according to any one of claims 1, 6, and 7, wherein the impedance auto-tuning system can monitor the output impedance of the preamplifier in real time. The detuning angle can be adjusted to control and adjust the parameters of the matching network, and automatically compensate the impedance change caused by the tetrode grid capacitance Ckg1 in a wide frequency band.

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