RF power source system

Abstract

This invention discloses a radio frequency power source system, comprising: a signal source module, a first-stage amplifier circuit, an ion beam current measurement circuit 8, a DC voltage generation circuit 7, a second-stage amplifier circuit 3, and a load resonant matching circuit 4. By integrating the control module and the load matching circuit, the invention solves the problems of large size and narrow load adaptability of existing radio frequency power source systems.

Description

Technical Field

[0001] This invention relates to the field of radio frequency power sources, and in particular to a radio frequency power source system. Background Technology

[0002] The generation of radio frequency plasma involves coupling radio frequency energy from a radio frequency power source into a discharge cavity via inductive or capacitive coupling. This ionizes the gas within the discharge cavity, transforming it into a plasma state and maintaining the generation of high-density plasma. Industrially, it has wide applications in radio frequency plasma and radio frequency ion source equipment; in space, it can be used in radio frequency plasma thrusters and radio frequency ion thrusters, etc.

[0003] Currently, there are two common types of radio frequency (RF) sources used for RF plasma generation. One type uses a fixed frequency output and a fixed matching circuit. This type of RF source cannot adapt to impedance matching when the load changes, which makes plasma generation difficult and makes it impossible to guarantee high-efficiency output of the RF source when the load changes. The other type is an RF source with a fixed frequency and a variable matching circuit. This type of RF source adjusts the variable capacitor in a closed loop according to the load change. However, because the variable capacitor and the corresponding adjustment device are large in size and the capacitor adjustment range is narrow, the system has the problems of large size and narrow load adaptability. Summary of the Invention

[0004] The purpose of this invention is to provide a radio frequency power source system that addresses the problems of large size and narrow load adaptability of existing radio frequency power source systems.

[0005] This invention provides a radio frequency power source system, comprising:

[0006] The signal source module is connected to the first-stage amplifier circuit, the load resonant matching circuit 4, the ion beam measurement circuit 8, and the DC voltage generation circuit 7. It receives the first analog signal coupled by the load resonant matching circuit 4, uses the first analog signal as a control quantity to generate square wave signals of different frequencies, and sends the square wave signals of different frequencies to the first-stage amplifier circuit. It also receives the second analog signal coupled by the ion beam measurement circuit 8, uses the second analog signal as a control quantity for the output voltage of the DC voltage generation circuit 7, and generates square wave signals with different duty cycles to send to the DC voltage generation circuit 7.

[0007] The first-stage amplifier circuit is connected to the second-stage amplifier circuit 3 and is used to amplify square wave signals of different frequencies in one stage before inputting them into the second-stage amplifier circuit 3.

[0008] The ion beam measurement circuit 8 is connected to the signal source module and is used to feed back the acquired ion beam analog small signal to the signal source module.

[0009] The DC voltage generating circuit 7 is connected to the signal source module and the second-stage amplifier circuit 3. It is used to amplify the square wave signals with different duty cycles generated by the signal source module and convert them into DC signals with adjustable output voltage. The DC signal is then input into the second-stage amplifier circuit 3 to control the load RF power output, thereby achieving the purpose of controlling the system ion beam current.

[0010] The second-stage amplifier circuit 3 is connected to the load resonant matching circuit 4 and is used to amplify the square wave signal after the first-stage power amplification and then input it into the load resonant matching circuit 4.

[0011] The load resonant matching circuit 4 is connected to the signal source module and the load. It is used to resonate and filter the square wave signal after the secondary amplification to obtain a quasi-sine wave signal, input the quasi-sine wave signal to the load, and feed back the coupled signal obtained by sampling the voltage / current at the load input terminal to the signal source module.

[0012] By employing embodiments of the present invention, the problems of large size and narrow load adaptability of existing RF power source systems are solved by integrating a control module and a load matching circuit.

[0013] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0014] 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.

[0015] Figure 1 This is a schematic diagram of an embodiment of the radio frequency power source system of the present invention.

[0016] Explanation of reference numerals in the attached figures:

[0017] 1: Control module; 2: Gate drive amplifier circuit; 3: Second stage amplifier circuit; 4: Load resonant matching circuit; 5: Incident and reflected power signal acquisition circuit; 6: Analog-to-digital conversion circuit; 7: DC voltage generation circuit; 8: Ion beam measurement circuit; 9: RF power transistor; 10: Second amplifying inductor; 11: Choke inductor; 12: Second amplifying capacitor; 13: Series capacitor; 14: Parallel capacitor; 15: First equivalent resistance; 16: Equivalent inductance of the plasma load itself; 17: Voltage sensor; 18: Current sensor; 19: Multiplier filter circuit; 20: Equivalent circuit of plasma load transmission line; 21: Equivalent inductance; 22: Second equivalent resistance. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0019] System Implementation Examples

[0020] According to embodiments of the present invention, a radio frequency power source system is provided. Figure 1 This is a schematic diagram of an embodiment of the radio frequency power source system of the present invention, as shown below. Figure 1 As shown, it specifically includes:

[0021] The signal source module is connected to the first-stage amplifier circuit, the load resonant matching circuit 4, the ion beam measurement circuit 8, and the DC voltage generation circuit 7. It receives the first analog signal coupled by the load resonant matching circuit 4, uses the first analog signal as a control quantity to generate square wave signals of different frequencies, and sends the square wave signals of different frequencies to the first-stage amplifier circuit. It also receives the second analog signal coupled by the ion beam measurement circuit 8, uses the second analog signal as a control quantity for the output voltage of the DC voltage generation circuit 7, and generates square wave signals with different duty cycles to send to the DC voltage generation circuit 7.

[0022] The first-stage amplifier circuit is connected to the second-stage amplifier circuit 3 and is used to amplify square wave signals of different frequencies in one stage before inputting them into the second-stage amplifier circuit 3.

[0023] The ion beam measurement circuit 8 is connected to the signal source module and is used to feed back the acquired ion beam analog small signal to the signal source module.

[0024] The DC voltage generating circuit 7 is connected to the signal source module and the second-stage amplifier circuit 3. It is used to amplify the square wave signals with different duty cycles generated by the signal source module and convert them into DC signals with adjustable output voltage. The DC signal is then input into the second-stage amplifier circuit 3 to control the load RF power output, thereby achieving the purpose of controlling the system ion beam current.

[0025] The second-stage amplifier circuit 3 is connected to the load resonant matching circuit 4 and is used to amplify the square wave signal after the first-stage power amplification and then input it into the load resonant matching circuit 4.

[0026] The load resonant matching circuit 4 is connected to the signal source module and the load. It is used to resonate and filter the square wave signal after the secondary amplification to obtain a quasi-sine wave signal, input the quasi-sine wave signal to the load, and feed back the coupled signal obtained by sampling the voltage / current at the load input terminal to the signal source module.

[0027] The signal source module mainly includes a control module 1 and an analog-to-digital converter circuit 6. The analog-to-digital converter circuit 6 converts the received first analog signal and second analog signal into digital signals. The control module 1 uses the two digital signals as control quantities to control the generation of a square wave signal PFM at a certain frequency and a square wave signal PWM at a certain duty cycle. The PFM signal is input to the first-stage amplifier circuit, and the PWM signal is input to the DC voltage generation circuit 7. The DC voltage generation circuit 7 generates an output voltage, which is transmitted to the second-stage amplifier circuit 3 through the choke inductor 11. The output voltage controls the load power at the output of the second-stage amplifier circuit 3.

[0028] The first-stage amplifier circuit is a gate-driven amplifier circuit 2. The control module 1 is connected to the gate-driven amplifier circuit 2. The second-stage amplifier circuit 3 includes: an RF power transistor 9, a second amplifying inductor 10, and a second amplifying capacitor 12. The RF power transistor 9 and the second amplifying inductor 10 are connected in series and then connected in parallel with the second amplifying capacitor 12. The two ends of the second amplifying capacitor 12 are connected to the load resonant matching circuit 4. The gate-driven amplifier circuit 2 is connected to the gate of the RF power transistor 9.

[0029] A PFM of a certain frequency is used to adjust the driving frequency of the gate drive amplifier circuit 2.

[0030] The connection between the second amplifying inductor 10 and the second amplifying capacitor 12 is connected to the choke inductor 11.

[0031] The load resonant matching circuit 4 includes: a series capacitor 13, a parallel capacitor 14, an equivalent inductance of the plasma load itself 16, a first equivalent resistance 15, an incident and reflected power signal acquisition circuit 5, and an equivalent circuit 20 for the plasma load transmission line; the second amplifying capacitor 12 is connected in series with the series capacitor 13 and in parallel with the parallel capacitor 14, the parallel capacitor 14 is connected to the incident and reflected power signal acquisition circuit 5, the incident and reflected power signal acquisition circuit 5 is connected to the equivalent circuit 20 for the plasma load transmission line, the equivalent circuit 20 for the plasma load transmission line is connected to the equivalent inductance of the plasma load itself 16, and the equivalent inductance of the plasma load itself 16 is connected to the first equivalent resistance 15.

[0032] The incident and reflected power signal acquisition circuit 5 includes a voltage sensor 17, a current sensor 18, and a multiplier filter circuit 19. The voltage sensor 17 is used to acquire the high-frequency voltage signal at the load input terminal, the current sensor 18 is used to acquire the high-frequency current signal at the load input terminal, and the multiplier filter circuit 19 is used to convert the acquired voltage or current signal into a first analog signal representing the incident or reflected power, and input the first analog signal into the analog-to-digital converter circuit 6.

[0033] The plasma load transmission line equivalent circuit 20 includes: an equivalent inductance 21 and a second equivalent resistance 22, which are connected in series. The equivalent inductance 21 is connected in series with the current sensor 18, and the second equivalent resistance 22 is connected in series with the plasma load's own equivalent inductance 16.

[0034] The second amplifying inductor 10 is used to control the drain-source voltage of the RF power transistor 9, the capacitor 12 is used to control the output voltage and current phase, so that the RF power transistor 9 operates in the zero-voltage turn-on and zero-current turn-off states, and the series capacitor 13 is used to isolate the DC voltage component in the RF signal generated by the second-stage amplifier circuit 3.

[0035] The frequency-tunable signal source and control module in the radio frequency plasma source system can be directly implemented using the main control chip (such as FPGA) in the plasma generation system without the need for additional hardware circuits, thereby reducing the number of components used in the system, improving the system integration, and further reducing the system size.

[0036] Furthermore, when applied to radio frequency ion sources or space radio frequency ion thrusters, the radio frequency source control module includes at least two control quantities: radio frequency reflected power and ion beam magnitude. On one hand, the real-time measured radio frequency reflected power is used as a function of the radio frequency gate drive frequency. Based on the load conditions and the set reflected power threshold, the system automatically adjusts the gate drive frequency, thereby achieving automatic load matching. Compared to general voltage / current phase monitoring and DC-power efficiency as feedback quantities, this design is simpler, improving system integration and reducing system size. On the other hand, the ion beam telemetry is processed by an A / D converter circuit. Based on the set ion beam magnitude, the control module calculates a PWM signal with a certain duty cycle to drive the drain DC power supply circuit, generating a certain voltage to supply the drain of the power transistor, thus adjusting the radio frequency power of the radio frequency power source and controlling the ion beam magnitude. The design of the radio frequency plasma source load resonant matching circuit is as follows:

[0037] A series-parallel resonant circuit is employed, consisting of an output matching capacitor or inductor of the RF power source and a plasma load (or, for inductively coupled plasma, the load is equivalent to an inductor and a resistor in series). When the load characteristics change, the telemetry reflected power value changes due to mismatch in the resonant circuit. This change is then controlled by a closed-loop control module to alter the gate drive frequency, thereby achieving impedance matching. Because the impedance matching circuit is directly located at the output of the RF power source, significant power loss occurs between the RF source and the plasma load if the transmission line is long, especially when the plasma load is inductively coupled. The equivalent parameters also become more complex. Therefore, this matching design is suitable for applications where the RF source and the plasma load are installed close to each other.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions to the technical solutions of the embodiments of the present invention do not cause the essence of the corresponding technical solutions to deviate from the scope of the present solution.

Claims

1. A radio frequency power source system, characterized by, The application relates to a control system for ion beam current, which comprises the following modules: a signal source module connected with a first-stage amplification circuit, a load resonant matching circuit (4), an ion beam current measuring circuit (8) and a direct-current voltage generating circuit (7), receives a first analog signal coupled by the load resonant matching circuit (4), generates square wave signals with different frequencies by taking the first analog signal as a control quantity, sends the square wave signals with different frequencies to the first-stage amplification circuit, receives a second analog signal coupled by the ion beam current measuring circuit (8), takes the second analog signal as a control quantity of the output voltage size of the direct-current voltage generating circuit (7), generates square wave signals with different duty cycles and sends the square wave signals to the direct-current voltage generating circuit (7); the first-stage amplification circuit is connected with a second-stage amplification circuit (3) and is used for inputting the square wave signals with different frequencies after one-stage power amplification into the second-stage amplification circuit (3); the ion beam current measuring circuit (8) is connected with the signal source module and is used for feeding back the collected ion beam current analog small signal to the signal source module; the direct-current voltage generating circuit (7) is connected with the signal source module and the second-stage amplification circuit (3) and is used for amplifying the square wave signals with different duty cycles generated by the signal source module into direct-current signals with adjustable output voltage and inputting the direct-current signals into the second-stage amplification circuit (3) to control the load radio frequency power output, so that the purpose of controlling the ion beam current of the control system is achieved; the second-stage amplification circuit (3) is connected with the load resonant matching circuit (4) and is used for inputting the square wave signals after two-stage amplification into the load resonant matching circuit (4); the load resonant matching circuit (4) is connected with the signal source module and a load and is used for obtaining quasi-sine wave signals after resonant filtering of the square wave signals after two-stage amplification, inputting the quasi-sine wave signals into the load, sampling the voltage / current of the input end of the load and feeding back the coupled signals to the signal source module; wherein, the load resonant matching circuit (4) comprises a series capacitor (13), a parallel capacitor (14), an equivalent inductance (16) of the plasma load itself, a first equivalent resistor (15), an incident reflected power signal acquisition circuit (5) and a plasma load transmission line equivalent circuit (20); the second amplification capacitor (12) is connected in series with the series capacitor (13) and is connected in parallel with the parallel capacitor (14), the parallel capacitor (14) is connected with the incident reflected power signal acquisition circuit (5), the incident reflected power signal acquisition circuit (5) is connected with the plasma load transmission line equivalent circuit (20), the plasma load transmission line equivalent circuit (20) is connected with the equivalent inductance (16) of the plasma load itself, and the equivalent inductance (16) of the plasma load itself is connected with the first equivalent resistor (15).

2. The system of claim 1, wherein, The signal source module specifically mainly includes a control module (1) and an analog-digital conversion circuit (6); the analog-digital conversion circuit (6) converts the received first analog signal and second analog signal into digital signals, and the control module (1) controls two-way digital signals as control quantities to generate a square wave signal PFM of a certain frequency and a square wave signal PWM of a certain duty cycle; wherein, the PFM signal is input to a first-stage amplification circuit, the PWM signal is input to a direct current voltage generation circuit (7), the direct current voltage generation circuit generates an output voltage, the output voltage is transmitted to a second-stage amplification circuit (3) through a choke inductance (11), and the output voltage controls the load power size of the output end of the second-stage amplification circuit (3).

3. The system of claim 2, wherein, The first-stage amplification circuit is a gate drive amplification circuit (2), the control module (1) is connected with the gate drive amplification circuit (2), and the second-stage amplification circuit (3) includes a radio frequency power tube (9), a second amplification inductance (10) and a second amplification capacitance (12); the radio frequency power tube (9) and the second amplification inductance (10) are connected in series and then connected in parallel with the second amplification capacitance (12), the two ends of the second amplification capacitance (12) are connected with a load resonant matching circuit (4), and the gate drive amplification circuit (2) is connected with the gate of the radio frequency power tube (9).

4. The system of claim 3, wherein, The PFM of a certain frequency is used for adjusting the driving frequency of the gate drive amplification circuit (2).

5. The system of claim 4, wherein, The connection position of the second amplification inductance (10) and the second amplification capacitance (12) is connected with the choke inductance (11).

6. The system of claim 1, wherein, The incident and reflected power signal acquisition circuit (5) includes a voltage sensor (17), a current sensor (18) and a multiplier filter circuit (19); the voltage sensor (17) is used for acquiring a high-frequency voltage signal at the input end of the load, the current sensor (18) is used for acquiring a high-frequency current signal at the input end of the load, and the multiplier filter circuit (19) is used for converting the acquired voltage or current signal into a first analog signal representing incident or reflected power and inputting the first analog signal into the analog-digital conversion circuit (6).

7. The system of claim 6, wherein, The plasma load transmission line equivalent circuit (20) includes an equivalent inductance (21) and a second equivalent resistance (22); the equivalent inductance (21) and the second equivalent resistance (22) are connected in series, the equivalent inductance (21) is connected in series with the current sensor (18), and the second equivalent resistance (22) is connected in series with the equivalent inductance (16) of the plasma load itself.

8. The system of claim 7, wherein, The second amplification inductance (10) is used for controlling the drain-source voltage of the radio frequency power tube (9), the second amplification capacitance (12) is used for controlling the phase of the output voltage and current, the radio frequency power tube (9) works in a zero-voltage turn-on and zero-current turn-off state, and the series capacitance (13) is used for isolating the direct current voltage component in the radio frequency signal generated by the second-stage amplification circuit (3).

Images