Radio frequency power supply power high-precision control system and control method based on TDC, and storage medium

Abstract

The invention provides a TDC-based radio frequency power supply power high-precision control system, a TDC-based radio frequency power supply power high-precision control method and a storage medium, which are used for solving various problems of an existing closed-loop control scheme based on analog detection and an existing closed-loop control scheme based on high-speed ADC sampling. According to the TDC-based high-precision control system for the power of the radio-frequency power supply, a voltage signal representing the incident power of the radio-frequency power supply is linearly converted into a pulse signal of which the frequency is in direct proportion to the voltage signal through a voltage-controlled oscillator, and then the pulse signal is digitally measured through a time-to-digital converter; and finally, a pulse period error is calculated through a digital controller so as to adjust the gain of a power amplifier in the radio frequency power supply in a closed-loop manner. Power detection is converted from a traditional analog voltage domain to a high-stability time measurement domain, the problems of temperature drift and nonlinear response caused by dependence on analog voltage measurement in a traditional analog detection scheme are fundamentally solved, and the power control precision of the radio frequency power supply is remarkably improved.

Description

Technical Field

[0001] This invention relates to a radio frequency power control system and control method, and more particularly to a high-precision radio frequency power control system, control method and storage medium based on TDC. Background Technology

[0002] As a core energy supply device, radio frequency (RF) power supplies play a crucial role in high-end industrial fields such as semiconductor manufacturing, plasma cleaning, and magnetron sputtering coating. The stability and accuracy of their output power directly determine the process results and product yield. Currently, the technical solutions for RF power supply power control are mainly divided into two categories: closed-loop control schemes based on analog detection and closed-loop control schemes based on high-speed ADC sampling.

[0003] The core drawback of closed-loop control schemes based on analog detection is that their accuracy is heavily dependent on the temperature characteristics of the analog devices. Changes in ambient temperature cause drift in the detector output voltage, necessitating complex temperature compensation circuits or frequent software calibration to maintain accuracy. This results in unsatisfactory long-term stability and repeatability. Furthermore, analog detectors exhibit significant nonlinear response characteristics in the small-signal region, leading to inconsistent accuracy across the entire power range. Control accuracy is difficult to guarantee in the low-power range, and the dynamic range is limited. While closed-loop control schemes based on high-speed ADC sampling avoid some of the problems of analog detection, they require high-speed, high-precision ADCs and powerful digital processing units, supplemented by complex digital signal processing algorithms. This results in a complex system architecture, high component costs, and high overall power consumption.

[0004] Therefore, there is an urgent need in this field for a new RF power control technology that can fundamentally overcome the aforementioned limitations and achieve high precision, high stability, and low complexity. The time-to-digital converter (TDC), as a device capable of achieving picosecond-level high-precision time interval measurement, offers a novel approach and direction for solving these problems in the field of RF power control. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of existing closed-loop control schemes based on analog detection, which require complex temperature compensation circuits or frequent software calibration to maintain accuracy, have unsatisfactory long-term stability and repeatability, and have difficulty in guaranteeing control accuracy in the low power range and have limited dynamic range, or the technical problems of closed-loop control schemes based on high-speed ADC sampling, which have complex system architecture, high component cost and high overall power consumption. The invention provides a high-precision RF power control system, control method and storage medium based on TDC.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: A high-precision power control system for radio frequency power supply based on TDC, wherein the radio frequency power supply includes a digital controller and a power amplifier, the output terminal of the digital controller is connected to the input terminal of the power amplifier, and the power amplifier is used for power output; its special feature is that it includes a power detection module, a voltage-controlled oscillator, a time-to-digital converter and a digital controller connected in sequence according to input and output; The power detection module includes a directional coupler and a detection circuit; the directional coupler is used to couple out a fixed proportion of the radio frequency electrical signal from the incident power output by the radio frequency power supply; the input terminal of the detection circuit is connected to the output terminal of the directional coupler and is used to convert the coupled radio frequency electrical signal into a DC voltage signal. The input terminal of the voltage-controlled oscillator is connected to the output terminal of the detector circuit, and is used to convert the input DC voltage signal into a pulse signal whose frequency is proportional to the DC voltage signal. The input of the time-to-digital converter is connected to the output of the voltage-controlled oscillator, and is used to convert the period information of the pulse signal into a digital quantity that can be read through a standard digital interface to obtain a pulse period measurement value. The input terminal of the digital controller is connected to the SPI communication pin of the time-to-digital converter. It is used to read the pulse period measurement value converted by the time-to-digital converter, compare the pulse period measurement value with the pre-stored target period T_set to obtain the pulse period error, calculate the control signal based on the pulse period error, and adjust the gain of the power amplifier in the RF power supply through the calculated control signal.

[0007] Furthermore, the detection circuit converts the coupled radio frequency electrical signal into a DC voltage signal using the following formula: ; Where V_pwr is the DC voltage signal output by the detector circuit, k is the conversion coefficient of the detector circuit, b is the bias, and U is the incident voltage corresponding to the coupled radio frequency signal.

[0008] Furthermore, the voltage-controlled oscillator converts the input DC voltage signal into a pulse signal with a frequency proportional to the DC voltage signal using the following formula: ; in, k_vco is the frequency of the pulse signal output by the voltage-controlled oscillator, k_vco is the voltage-to-frequency conversion gain of the voltage-controlled oscillator, and f_offset is the output frequency offset.

[0009] Furthermore, the time-to-digital converter achieves digital measurement of the pulse signal using the following formula: ; in, This is the measured value of the pulse period.

[0010] Furthermore, the digital controller includes a comparator and a PID controller, and the controlled object is a DDS; The first input terminal of the comparator is used to receive the pulse period measurement value T_measure, and the second input terminal is used to receive the pre-stored target period T_set. The comparator is used to compare the pulse period measurement value T_measure output by the time-to-digital converter with the pre-stored target period T_set to obtain the pulse period error. The input terminal of the PID controller is connected to the output terminal of the comparator, and is used to calculate the pulse period error through proportional, integral, and derivative adjustment, and output a control quantity. The input terminal of the DDS is connected to the output terminal of the PID controller, and is used to adjust its own parameters according to the control quantity output by the PID controller to generate an AC drive signal that meets the set power output. Its output terminal is connected to the input terminal of the power amplifier to adjust the gain of the power amplifier.

[0011] In addition, based on the above-mentioned high-precision control system for radio frequency power based on TDC, the present invention also provides a high-precision control method for radio frequency power based on TDC, which is characterized by including the following steps: When the incident power output by the radio frequency power supply is transmitted through the transmission line, the directional coupler couples out a fixed proportion of radio frequency electrical signal from the incident power. The coupled radio frequency electrical signal is converted into a DC voltage signal by the detection circuit, and then converted into a pulse signal with a frequency proportional to the DC voltage signal by the voltage-controlled oscillator. The time-to-digital converter digitizes the input pulse signal to obtain a pulse period measurement value; The digital controller first compares the measured pulse period with the pre-stored target period T_set to obtain the pulse period error, then calculates the control signal based on the pulse period error, and finally adjusts the gain of the power amplifier in the RF power supply through the calculated control signal to complete the closed-loop control of the RF power supply.

[0012] In addition, the present invention also provides a computer-readable storage medium storing a computer program thereon, wherein the program, when executed by a processor, implements the steps of the above-described high-precision control method for radio frequency power supply based on TDC.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The high-precision RF power control system based on TDC provided by this invention uses a voltage-controlled oscillator and a time-to-digital converter to form an innovative circuit. First, the voltage signal characterizing the incident power of the RF power supply is linearly converted into a pulse signal with a frequency proportional to the voltage-controlled oscillator. Then, the time-to-digital converter performs picosecond-level precision digital measurement on this pulse signal. Finally, the digital controller compares the measured pulse period with the pre-stored target period T_set and adjusts the gain of the power amplifier in the RF power supply in a closed loop, thereby achieving high-precision and high-stability control of the incident power of the RF power supply. This invention, by constructing a direct conversion link of "power-time-digital feedback", converts power detection from the traditional analog voltage domain to a highly stable time measurement domain, fundamentally overcoming the temperature drift and nonlinear response problems caused by the reliance on analog voltage measurement in traditional analog detection schemes, and significantly improving the power control accuracy of the RF power supply.

[0014] 2. The high-precision RF power control system based on TDC provided by this invention has a simple circuit structure and low cost. By constructing a control architecture with a digital feedback element as the core of a time-to-digital converter, the incident power information of the RF power supply is directly converted into a high-precision digital time quantity. This ensures that the measured value of the feedback pulse period is completely free from analog interference during transmission and processing and does not require analog-to-digital conversion. This overcomes the technical problems of traditional closed-loop control schemes based on high-speed ADC sampling, where analog signal transmission is susceptible to interference and digital schemes require high-speed and high-precision ADCs, resulting in system complexity and high cost.

[0015] 3. The high-precision RF power control system based on TDC provided by this invention utilizes the picosecond-level time resolution and fast response characteristics of the time-to-digital converter to achieve high-speed and precise measurement of changes in the incident power of the RF power supply. Its dynamic response speed far exceeds that of traditional solutions, thereby solving the technical problem that existing RF power control systems are unable to cope with rapid load changes due to signal processing delays.

[0016] 4. The high-precision RF power control method based on TDC provided by this invention is simple, practical, and easy to operate. Through digital calibration, it achieves higher control accuracy and higher dynamic response, making it suitable for application scenarios that are cost-sensitive and require high control accuracy. Attached Figure Description

[0017] Figure 1 This is a schematic block diagram of the power-time conversion of the high-precision RF power control system based on TDC of the present invention. Figure 2 This is a control timing diagram of the high-precision RF power control method based on TDC of the present invention; Figure 3This is a schematic block diagram illustrating the control principle of the high-precision RF power control method based on TDC of the present invention. Detailed Implementation

[0018] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown, a high-precision RF power control system based on TDC includes a power detection module, a voltage-controlled oscillator, a time-to-digital converter, and a digital controller connected in sequence according to input and output.

[0020] The power detection module includes a directional coupler and a detection circuit; wherein, the directional coupler is used to detect the incident power P output from the RF power supply. o A fixed-ratio radio frequency electrical signal is coupled out from the directional coupler; the input of the detector circuit is connected to the output of the directional coupler to convert the coupled radio frequency electrical signal into a DC voltage signal.

[0021] The coupling ratio of the directional coupler can be set as needed; the DC voltage signal output by the detector circuit is proportional to the incident voltage signal corresponding to the coupled radio frequency signal, and its specific expression is as follows: ; Where V_pwr is the DC voltage signal output by the detector circuit, k is the conversion coefficient of the detector circuit, b is the bias, and U is the incident voltage corresponding to the coupled radio frequency signal.

[0022] The input of the voltage-controlled oscillator (VCO) is connected to the output of the detector circuit. It is used to convert the DC voltage signal output by the detector circuit into a pulse signal with a frequency proportional to the DC voltage signal. Its specific expression is as follows: ; in, Let k_vco be the frequency of the pulse signal output by the voltage-controlled oscillator (VCO), k_vco be the voltage-to-frequency conversion gain of the VCO, and f_offset be the output frequency offset. In practical applications, the output frequency offset f_offset can be made close to zero through circuit design.

[0023] The input of the time-to-digital converter (TDC) is connected to the output of the voltage-controlled oscillator (VCO). It is used to directly, quickly, and accurately convert the period information (time interval information) of a pulse signal into a digital quantity that can be read through a standard digital interface (SPI), thus obtaining the pulse period measurement value. This enables near real-time digital and on-chip measurement of the pulse signal period, as expressed below: .

[0024] The pulse period measurement value obtained by the time-to-digital converter is used as a direct feedback input to the digital controller for feedback regulation.

[0025] The digital controller stores a target period T_set, which is related to the power setting value issued by the user. The relationship between the user-issued power setting value P_set and the target period T_set needs to be established through testing to create a mapping relationship between power P and time T, recording the period values ​​corresponding to multiple power points to form a power-time correspondence.

[0026] The digital controller includes a comparator and a PID controller, with the controlled object being a DDS. The first input of the comparator receives the pulse period measurement value T_measure after pulse quantization, and the second input receives the pre-stored target period T_set. The comparator compares the pulse period measurement value T_measure output by the time-to-digital converter with the pre-stored target period T_set to obtain the pulse period error. The input of the PID controller is connected to the output of the comparator, and it calculates the pulse period error through proportional, integral, and derivative adjustments, outputting a control quantity. The input of the DDS is connected to the output of the PID controller, and it adjusts its parameters according to the control quantity output by the PID controller to generate an AC drive signal that meets the set power output. Its output is connected to the input of the power amplifier, used to adjust the gain of the power amplifier in the RF power supply.

[0027] The control method of the above-mentioned high-precision RF power control system based on TDC has the following specific control flow: The incident power P output by the RF power supply o When transmitted through a transmission line, the directional coupler receives the incident power P from the transmission line. o A fixed-ratio radio frequency (RF) signal is coupled out from the middle, and the coupled RF signal is converted into a DC voltage signal by a detection circuit. Then it is converted into a frequency by a voltage-controlled oscillator. With DC voltage signal A pulse signal that is directly proportional to the signal.

[0028] At this point, the time-to-digital converter digitizes the input pulse signal to obtain the pulse period measurement value. .like Figure 2 The diagram shown is a timing diagram of the high-precision control of the RF power supply in this embodiment. It illustrates the output incident power P of the RF power supply during time intervals 0-t1. o When P1 is the frequency of the pulse signal output by the voltage-controlled oscillator (VCO). f1 is the measured pulse period output by the time-to-digital converter (TDC). Let T1 be the incident power P output by the RF power supply during the time interval t1-t2. o When P2 is increased, the frequency of the pulse signal output by the voltage-controlled oscillator (VCO) increases. The corresponding value is increased to f2, while the pulse period measurement value output by the time-to-digital converter (TDC) is... Then it decreases to T2.

[0029] The control principle of the high-precision RF power control method based on TDC of this invention is as follows: Figure 3 As shown, the user sends a power setting value P_set, which is used to obtain the target period T_set through a corresponding relationship; the incident power P output by the RF power supply... o The power-time conversion is achieved through a feedback loop consisting of a power detection module, a voltage-controlled oscillator, and a time-to-digital converter, thereby obtaining the pulse period measurement value T_measure. The comparator in the digital controller compares the pulse period measurement value T_measure with the target period T_set, calculating the pulse period error Err. This error maps the power error information between the power setpoint of the RF power supply and the actual output incident power, which is then accurately identified and controlled by the PID controller. The PID controller calculates the control signal based on the pulse period error Err and adjusts the gain of the power amplifier in the RF power supply according to the calculated control signal, completing the closed-loop control of the RF power supply. The specific control flow is as follows: After obtaining the pulse period error Err, it serves as the feedback input to the PID controller. The PID controller performs proportional, integral, and derivative adjustments on the pulse period error Err, outputting a control quantity U. The control quantity U is input to the controlled object DDS (Direct Digital Synthesizer). The DDS adjusts its parameters according to the control quantity U to generate an AC drive signal that meets the set power output. The drive signal output by the DDS enters the power amplifier, is amplified to the target power, and then outputs.

[0030] The control method of the high-precision control system for radio frequency power supply based on TDC of the present invention can be applied in a computer-readable storage medium. The computer-readable storage medium stores a computer program, and the above control method can be stored as a computer program in the computer-readable storage medium. When the computer program is executed by a processor, it implements the steps of the above control method.

[0031] The above description is only used to illustrate the technical solutions of the present invention, and is not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A high-precision control system for radio frequency power supply based on TDC, wherein the radio frequency power supply includes a digital controller and a power amplifier, the output terminal of the digital controller is connected to the input terminal of the power amplifier, and the power amplifier is used for power output; characterized in that: It includes a power detection module, a voltage-controlled oscillator, a time-to-digital converter, and a digital controller connected in sequence according to their inputs and outputs; The power detection module includes a directional coupler and a detection circuit; the directional coupler is used to couple out a fixed proportion of the radio frequency electrical signal from the incident power output by the radio frequency power supply; the input terminal of the detection circuit is connected to the output terminal of the directional coupler and is used to convert the coupled radio frequency electrical signal into a DC voltage signal. The input terminal of the voltage-controlled oscillator is connected to the output terminal of the detector circuit, and is used to convert the input DC voltage signal into a pulse signal whose frequency is proportional to the DC voltage signal. The input of the time-to-digital converter is connected to the output of the voltage-controlled oscillator, and is used to convert the period information of the pulse signal into a digital quantity that can be read through a standard digital interface to obtain a pulse period measurement value. The input terminal of the digital controller is connected to the SPI communication pin of the time-to-digital converter. It is used to read the pulse period measurement value converted by the time-to-digital converter, compare the pulse period measurement value with the pre-stored target period T_set to obtain the pulse period error, calculate the control signal based on the pulse period error, and adjust the gain of the power amplifier in the RF power supply through the calculated control signal.

2. The high-precision RF power control system based on TDC according to claim 1, characterized in that: The detection circuit converts the coupled radio frequency electrical signal into a DC voltage signal using the following formula: ； Where V_pwr is the DC voltage signal output by the detector circuit, k is the conversion coefficient of the detector circuit, b is the bias, and U is the incident voltage corresponding to the coupled radio frequency signal.

3. The high-precision RF power control system based on TDC according to claim 2, characterized in that: The voltage-controlled oscillator converts the input DC voltage signal into a pulse signal with a frequency proportional to the DC voltage signal using the following formula: ； in, k_vco is the frequency of the pulse signal output by the voltage-controlled oscillator, k_vco is the voltage-to-frequency conversion gain of the voltage-controlled oscillator, and f_offset is the output frequency offset.

4. The high-precision radio frequency power control system based on TDC according to claim 3, characterized in that: The time-to-digital converter achieves digital measurement of pulse signals using the following formula: ； in, This is the measured value of the pulse period.

5. The high-precision radio frequency power control system based on TDC according to any one of claims 1-4, characterized in that: The digital controller includes a comparator and a PID controller, and the controlled object is a DDS. The first input terminal of the comparator is used to receive the pulse period measurement value T_measure, and the second input terminal is used to receive the pre-stored target period T_set. The comparator is used to compare the pulse period measurement value T_measure output by the time-to-digital converter with the pre-stored target period T_set to obtain the pulse period error. The input terminal of the PID controller is connected to the output terminal of the comparator, and is used to calculate the pulse period error through proportional, integral, and derivative adjustment, and output a control quantity. The input terminal of the DDS is connected to the output terminal of the PID controller, and is used to adjust its own parameters according to the control quantity output by the PID controller to generate an AC drive signal that meets the set power output. Its output terminal is connected to the input terminal of the power amplifier to adjust the gain of the power amplifier.

6. A high-precision RF power control method based on TDC, based on the high-precision RF power control system based on TDC as described in any one of claims 1-5, characterized in that, Includes the following steps: When the incident power output by the radio frequency power supply is transmitted through the transmission line, the directional coupler couples out a fixed proportion of radio frequency electrical signal from the incident power. The coupled radio frequency electrical signal is converted into a DC voltage signal by the detection circuit, and then converted into a pulse signal with a frequency proportional to the DC voltage signal by the voltage-controlled oscillator. The time-to-digital converter digitizes the input pulse signal to obtain a pulse period measurement value; The digital controller first compares the measured pulse period with the pre-stored target period T_set to obtain the pulse period error, then calculates the control signal based on the pulse period error, and finally adjusts the gain of the power amplifier in the RF power supply through the calculated control signal to complete the closed-loop control of the RF power supply.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by the processor, it implements the steps of the high-precision RF power control method based on TDC as described in claim 6.

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