Signal modulation circuit and high-frequency plasma surgical equipment

Abstract

The invention relates to the technical field of medical instruments, in particular to a signal modulation circuit and high-frequency plasma surgical equipment, and the signal modulation circuit comprises an analog switch, a slope control resistor, a coupling capacitor and a variable gain operational amplifier; the analog switch is driven by a low-frequency PWM signal, when the level of the low-frequency PWM signal is a high level, the analog switch connects the coupling capacitor with a high-frequency signal, and when the level of the low-frequency PWM signal is a low level, the analog switch enables the coupling capacitor to be grounded through the slope control resistor. According to the invention, the use of an analog multiplier is omitted through a new circuit form, so that the hardware cost is effectively reduced; even if phase truncation occurs, the voltage can be in smooth transition, and high-frequency noise is suppressed; the signal amplification consistency of the driving part is higher, the distortion is lower, and a post-stage load can be directly driven; by means of safety measures, the situation that operation continuity is affected by frequent mistaken shutdown of equipment can be avoided, it is ensured that energy is cut off immediately when real overload occurs, and treatment safety and system reliability are balanced fundamentally.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a signal modulation circuit and a high-frequency plasma surgical device. Background Technology

[0002] Traditional high-frequency surgical equipment transmits high-frequency signals of hundreds of kHz to the surgical instruments, generating high heat at the instrument tip and the point of contact with the tissue, thus achieving the effect of cutting or coagulation. Because these devices operate based on thermal effects, they are prone to causing thermal damage to surrounding healthy tissue and often produce noticeable sparks and significant amounts of smoke, which is detrimental to both patients and medical personnel.

[0003] To address the aforementioned issues, high-frequency plasma surgical devices are currently being used to replace traditional high-frequency surgical devices. Because these devices operate at a higher frequency than traditional high-frequency surgical devices, their high-frequency current skin effect is more pronounced. When the instrument tip comes into contact with the tissue, the high-frequency current causes the tissue fluid inside the tissue to decompose and generate plasma. This process enables tissue cutting and coagulation.

[0004] In high-frequency plasma surgical equipment, it is necessary to generate electrocautery or electrocoagulation signals with variable amplitude and duty cycle internally. For the signal modulation section, it typically consists of a high-frequency signal of 200K-5MHz and a low-frequency PWM signal of around 20KHz. For example... Figure 1 As shown, existing technology uses two analog multipliers to achieve signal modulation. Analog multiplier 1 multiplies the high-frequency signal with the target amplitude signal from the DAC to achieve amplitude modulation of the high-frequency signal; analog multiplier 2 multiplies the output signal of analog multiplier 1 with a low-frequency PWM signal to achieve low-frequency PWM modulation. In this modulation scheme for electrical switching or electrocoagulation signals based on analog multipliers, the use of expensive analog multipliers affects the final product hardware cost. Summary of the Invention

[0005] This invention provides a signal modulation circuit and a high-frequency plasma surgical device, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A signal modulation circuit includes an analog switch, a slope control resistor, a coupling capacitor, and a variable gain operational amplifier;

[0008] The analog switch is driven by a low-frequency PWM signal. When the level of the low-frequency PWM signal is high, the analog switch connects the coupling capacitor to the high-frequency signal. When the level of the low-frequency PWM signal is low, the analog switch grounds the coupling capacitor through the slope control resistor.

[0009] The variable gain operational amplifier amplifies the signal output from the coupling capacitor, and the control voltage of the variable gain operational amplifier is controlled by the target amplitude signal from the DAC.

[0010] Furthermore, the analog switch is a single-pole double-throw switch.

[0011] Furthermore, the values ​​of the slope control resistor and the coupling capacitor are determined based on the actual operating frequency of the high-frequency signal.

[0012] Furthermore, the value of the coupling capacitor is determined based on the actual operating frequency of the high-frequency signal, and the value of the slope control resistor is calculated based on the actual operating frequency of the high-frequency signal and the value of the coupling capacitor.

[0013] Furthermore, the method for calculating the slope control resistor includes:

[0014] Determine the circuit parameters, including the actual operating frequency of the high-frequency signal, the coupling capacitance value, and the target discharge time;

[0015] Establish an RC discharge model:

[0016] in,

[0017] u C This is the capacitor voltage, in volts (V).

[0018] U is the discharge initiation voltage, which is determined by the phase of the high-frequency signal;

[0019] R is the resistance value of the slope control resistor, in Ω;

[0020] C is the coupling capacitance value, in F;

[0021] t is the discharge time, in seconds;

[0022] RC is the time constant, measured in seconds (s).

[0023] The degree of voltage decay within the target discharge time is set, and the value of the time constant is calculated based on the degree of decay.

[0024] The slope control resistor is calculated based on the time constant and the coupling capacitance value.

[0025] Furthermore, the method for calculating the slope control resistor also includes:

[0026] The slope control resistor obtained from the calculation is adjusted, and the adjustment is made at least based on the error of the coupling capacitor, the error of the slope control resistor, and the internal resistance of the analog switch.

[0027] A high-frequency plasma surgical device, comprising:

[0028] The signal modulation circuit described above outputs a modulated signal;

[0029] The driving circuit performs primary power amplification on the modulation signal;

[0030] The radio frequency power amplifier circuit performs a secondary power amplification on the modulated signal that has already undergone primary power amplification;

[0031] A step-up transformer boosts the voltage of the modulated signal that has undergone secondary power amplification so that the output signal matches the impedance of the human body.

[0032] The driving section includes a high-speed operational amplifier, a balancing resistor, a gain control resistor, and a feedback resistor. The non-inverting input of the high-speed operational amplifier is connected to the output of the variable gain operational amplifier of the signal modulation circuit through the balancing resistor, and the inverting input is grounded through the gain control resistor. The output of the high-speed operational amplifier is connected to the inverting input through the feedback resistor.

[0033] Furthermore, the step-up transformer undergoes at least two stages of voltage boosting.

[0034] Furthermore, high-frequency plasma surgical equipment also includes:

[0035] The output power sampling module collects and processes the operating signal of the step-up transformer, calculates the current output power of the output signal, and obtains the calculation result.

[0036] The output threshold setting module sets the overload protection threshold according to the output requirements of the high-frequency plasma surgical equipment.

[0037] The safety logic module determines the overload occurrence time by comparing the calculation result with the overload protection threshold, and generates an overload protection signal when an overload occurs. The overload protection signal is used to control the signal modulation circuit and the drive circuit to stop working.

[0038] Furthermore, the security logic module is triggered by the calculation result;

[0039] After being triggered, the safety logic module then compares the calculation result with the overload protection threshold.

[0040] The technical solution of this invention can achieve the following technical effects:

[0041] This invention omits the use of analog multipliers through a new circuit configuration, effectively reducing hardware costs. When the low-frequency PWM signal is low, the analog switch grounds the coupling capacitor through a slope control resistor instead of directly short-circuiting it. The slope control resistor limits the discharge current, thus controlling the rate of change of the capacitor voltage to be slower. In this case, even if phase truncation occurs, the voltage will not change abruptly but will smoothly transition to zero, thereby reducing discontinuities and suppressing high-frequency noise.

[0042] The driving section uses high-speed operational amplifiers for signal amplification and driving. Because the high-speed operational amplifier introduces negative feedback control during operation, the signal amplification consistency is higher and the distortion is lower. The signal amplification factor can be precisely adjusted by adjusting the feedback resistor. The high-speed operational amplifier has a strong load-driving capability, and the signal output by the high-speed operational amplifier can directly drive the subsequent load.

[0043] By employing an output power sampling module, an output threshold setting module, and a safety logic module, the safety of high-frequency plasma surgical equipment can be improved. The safety logic module first initiates threshold comparison based on the calculation result, and then determines the triggering of overload protection through threshold comparison. This avoids frequent accidental shutdowns of the equipment that affect the continuity of surgery, and ensures that energy is immediately cut off in the event of a real overload, thus fundamentally balancing treatment safety and system reliability. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of a traditional signal modulation and driving scheme in the background technology;

[0046] Figure 2 This is a schematic diagram of the signal modulation circuit in Example 1;

[0047] Figure 3 The flowchart shows the calculation process for the slope control resistor.

[0048] Figure 4 The flowchart shows the optimization calculation process for the slope control resistor.

[0049] Figure 5 This is a schematic diagram of the signal modulation and driving scheme in Example 2;

[0050] Figure 6 This is a partial frame diagram of the high-frequency plasma surgical device in Example 2;

[0051] Figure 7 This is a partial optimized framework diagram of the high-frequency plasma surgical device in Example 2;

[0052] Figure 8 This is a complete frame diagram of the high-frequency plasma surgical device in Example 2. Detailed Implementation

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0054] Example 1:

[0055] like Figure 2 As shown, a signal modulation circuit includes an analog switch, a slope control resistor, a coupling capacitor, and a variable gain operational amplifier;

[0056] The analog switch is driven by a low-frequency PWM signal. When the low-frequency PWM signal is high, the analog switch connects the coupling capacitor to the high-frequency signal. When the low-frequency PWM signal is low, the analog switch grounds the coupling capacitor through the slope control resistor.

[0057] The variable gain op-amp amplifies the signal output by the self-coupling capacitor, and the control voltage of the variable gain op-amp is controlled by the target amplitude signal from the DAC.

[0058] This invention eliminates the need for an analog multiplier through a new circuit design, effectively reducing hardware costs.

[0059] In this embodiment, the coupling capacitor is used to transmit high-frequency signals. Since the duty cycle of the low-frequency PWM signal is variable, when the low-frequency PWM signal switches from high to low, the analog switch abruptly changes the connection state of the coupling capacitor. This can cause the high-frequency signal to be interrupted at any phase point, resulting in phase truncation and a voltage surge. In a modulation circuit, the ideal output is a smooth, amplitude-controlled signal, but phase truncation disrupts this smoothness, distorting the output signal and reducing modulation accuracy.

[0060] To address the aforementioned issues, this embodiment employs a slope control resistor that functions when the low-frequency PWM signal is at a low level. Specifically, based on the change in the analog switch's on / off relationship, it works in conjunction with the coupling capacitor to control the rate of change of voltage level during phase truncation. When the low-frequency PWM signal is low, the analog switch grounds the coupling capacitor through the slope control resistor instead of directly short-circuiting it. The slope control resistor limits the discharge current, thus controlling and slowing down the rate of change of the capacitor voltage. In this case, even if phase truncation occurs, the voltage will not abruptly change but will smoothly transition to zero, thereby reducing discontinuities and suppressing high-frequency noise.

[0061] The high-frequency signal referred to in this embodiment is the same as the high-frequency signal in the background art, with a frequency of 200K-5MHz.

[0062] Preferably, in this embodiment, the simulated switch is a single-pole double-throw switch.

[0063] As a preferred embodiment of the above, the values ​​of the slope control resistor and the coupling capacitor are determined based on the actual operating frequency of the high-frequency signal. More specifically, the value of the coupling capacitor is determined based on the actual operating frequency of the high-frequency signal, and the value of the slope control resistor is calculated based on the actual operating frequency of the high-frequency signal and the value of the coupling capacitor.

[0064] like Figure 3 As shown, as a preferred embodiment of the above, this embodiment provides a specific calculation method for the slope control resistor, including:

[0065] S1: Determine the circuit parameters, including the actual operating frequency of the high-frequency signal, the coupling capacitance value, and the target discharge time; in this embodiment, the actual operating frequency of the high-frequency signal is 4×10⁻⁶. 6 Hz, coupling capacitance value is 10 -8 F, the target discharge time, i.e., the duration for which the desired capacitor voltage significantly decays, is taken as one high-frequency signal period T, which is 2.5 × 10⁻⁶. -7 s;

[0066] S2: Establishing the RC discharge model:

[0067]

[0068] in,

[0069] u C This is the capacitor voltage, in volts (V).

[0070] U is the discharge initiation voltage, which is determined by the phase of the high-frequency signal;

[0071] R is the resistance value of the slope control resistor, in Ω;

[0072] C is the coupling capacitance value, in F;

[0073] t is the discharge time, in seconds;

[0074] RC is the time constant, measured in seconds (s).

[0075] The equation represents the capacitor voltage u. C The attenuation equation is as follows: when the low-frequency PWM signal is low, the coupling capacitor is grounded through the slope control resistor, forming a first-order RC discharge circuit. It constitutes the exponential decay factor and determines the degree of power attenuation;

[0076] S3: Set the rate of voltage decay of the capacitor within the target discharge time, and calculate the value of the time constant based on the rate of decay; in this embodiment, the target discharge time t = T is set so that the capacitor voltage decays to 36.8% of the discharge initiation voltage, because e -1 ≈0.368, in this embodiment, RC is considered to be T at this time; of course, when the target discharge time and the degree of capacitor voltage decay are different, different time constants will be obtained, resulting in different embodiments, which will not be elaborated here;

[0077] S4: Calculate the slope control resistor based on the time constant and coupling capacitance value. According to the above-mentioned value relationship in this embodiment, R = T / C = 2.5 × 10⁻⁶ in this step. -7 / 10 -8 =25Ω.

[0078] In this embodiment, the value of the slope control resistor is obtained directly by calculating the high-frequency period and capacitance parameters, transforming the traditional empirical design into a predictable mathematical model. The mathematical constraint RC=T is used to establish the accurate calculation of the slope resistor. The high-frequency signal period and coupling capacitance value are inherent parameters of the circuit, and the calculation is reproducible.

[0079] To further ensure the accuracy of signal modulation, as a preferred embodiment of the above, such as Figure 4 As shown, the calculation method for the slope control resistor also includes:

[0080] S5: Adjust the slope control resistor obtained from the calculation. The adjustment should be based at least on the error of the coupling capacitor, the error of the slope control resistor, and the internal resistance of the analog switch.

[0081] Specifically, coupling capacitor errors often cause the time constant to deviate from the theoretical value, resulting in uncontrolled discharge slope; slope control resistor errors cause the decay rate to deviate from the design target; the internal resistance of the analog switch increases the actual time constant due to its on-resistance, thus slowing down the discharge. To solve these problems, when adjusting based solely on the above parameters, the system error can be quantified first, for example:

[0082] Set the capacitor error coefficient Resistance error coefficient Switch internal resistance compensation value R on Where ΔC and ΔR are the errors of the coupling capacitor and the slope control resistor, respectively, and R on Typical values ​​can be selected based on the specific device chosen;

[0083] Then, calculate the final resistance value R. final The specific formula is used. In this embodiment, the specific value k can be taken as follows: C =1.1, k R =1.05, T=250ns, C=10nF, R on =3Ω, and the final calculated R final =25.875Ω.

[0084] Example 2:

[0085] like Figure 5 and 6 As shown, a high-frequency plasma surgical device includes:

[0086] The signal modulation circuit described in Example 1 outputs a modulated signal;

[0087] The driving circuit performs primary power amplification on the modulated signal;

[0088] The radio frequency power amplifier circuit performs a secondary power amplification on the modulated signal that has already undergone primary power amplification;

[0089] A step-up transformer boosts the voltage of the modulated signal that has undergone secondary power amplification so that the output signal matches the impedance of the human body.

[0090] The driving section includes a high-speed operational amplifier, a balancing resistor, a gain control resistor, and a feedback resistor. The non-inverting input of the high-speed operational amplifier is connected to the output of the variable gain operational amplifier of the signal modulation circuit through the balancing resistor, and the inverting input is grounded through the gain control resistor. The output of the high-speed operational amplifier is connected to the inverting input through the feedback resistor.

[0091] like Figure 1 As shown, traditional solutions use a low-power RF power amplifier for primary signal amplification in the driver section. When using an RF power amplifier for amplification, the input and output impedances need to be matched, and the voltage gain is significantly affected by temperature and input / output impedance, impacting signal consistency and increasing debugging difficulty during production. Furthermore, the low-power RF power amplifier used in the driver section requires a large quiescent current due to the operating bias voltage, resulting in significant heat generation. This heat generation causes temperature drift in the amplification characteristics, affecting signal accuracy.

[0092] In this embodiment, a high-speed operational amplifier (op-amp) is used for signal amplification and driving in the driving section. Because the high-speed op-amp introduces negative feedback control during operation, the signal amplification consistency is higher and the distortion is lower. The signal amplification factor can be precisely adjusted by adjusting the feedback resistor. The high-speed op-amp has strong load-driving capability, and the signal output from it can directly drive the subsequent load. High-speed op-amps, especially current-feedback op-amps, support parallel current amplification, so using a high-speed op-amp as the driving section results in lower output impedance and stronger load-driving capability in the subsequent stage.

[0093] The high-frequency plasma surgical device in this embodiment generates a modulation signal resistant to phase cutoff distortion by using the signal modulation circuit in Embodiment 1. After primary power amplification, the signal is driven by the RF power amplifier input. After secondary power amplification, the modulation signal can be boosted to surgical-grade power. After impedance matching, the signal is boosted to the high voltage required for surgery. Specifically, the boost transformer performs at least two staged boosting steps.

[0094] As a preferred embodiment of the above embodiments, in order to improve the safety of the high-frequency plasma surgical device, such as... Figure 7 As shown, the high-frequency plasma surgical device also includes:

[0095] The output power sampling module collects and processes the operating signal of the step-up transformer, calculates the current output power of the output signal, and obtains the calculation result.

[0096] The output threshold setting module sets the overload protection threshold according to the output requirements of the high-frequency plasma surgical equipment.

[0097] The safety logic module determines the overload occurrence time by comparing the calculation results with the overload protection threshold, and generates an overload protection signal when an overload occurs. The overload protection signal is used to control the signal modulation circuit and the drive circuit to stop working.

[0098] In this embodiment, the output power sampling module acquires and processes the operating signal of the step-up transformer and obtains the calculation result. This can be done in various ways. For example, the output power sampling module synchronously acquires the instantaneous values ​​of the primary side voltage and current of the step-up transformer, integrates their product, and multiplies it by the transformer efficiency compensation coefficient to calculate the output power in real time. The compensation coefficient can be obtained through pre-calibration. This method avoids the risks of direct high-voltage sampling, eliminates the need for high-voltage isolation sensors, and reduces costs. Of course, the above method is only one way to obtain the calculation result, but it is not the only method. For example, higher-precision direct sampling of the secondary side can also achieve the technical objective of this invention. Other methods that can achieve the objective of this invention are not listed here, but all are within the protection scope of this invention.

[0099] As a preferred embodiment of the above, the safety logic module is triggered by the calculation result. After triggering, the safety logic module compares the calculation result with the overload protection threshold to determine whether to trigger the overload protection function. During this process, setting the overload protection threshold prevents accidental triggering of the overload protection function. Simultaneously, in this embodiment, the safety logic module monitors the power supply and fault status of each module in the system and outputs a global fault signal through logic gate circuits. This global fault signal directly blocks the modulation signal output upon triggering, further enhancing equipment safety.

[0100] In this preferred solution, a dual-determination mechanism is used to achieve precise overload protection: the safety logic module first initiates threshold comparison based on the calculation result, and then determines the triggering of overload protection through the comparison of the thresholds. This avoids frequent accidental shutdowns of the equipment that may affect the continuity of the surgery, and ensures that the energy is cut off immediately in the event of a real overload, thus fundamentally balancing treatment safety and system reliability.

[0101] like Figure 8 The diagram shows a detailed framework of a high-frequency plasma surgical device. The solutions described above can be combined with the following conventional modules to obtain a complete product form. Specifically, the modules can be selected and combined according to the required functions. The diagram also includes:

[0102] Switching power supply: Steps down the external AC voltage to provide voltage power to the RF power amplifier. The typical output voltage is 48V, and it also outputs a 12V auxiliary power supply to power other modules.

[0103] Human-computer interaction touch screen: Used to display the working parameters, working status, alarm information, etc. of the high-frequency plasma surgical equipment, and supports touch operation for modifying the current working parameters of the high-frequency plasma surgical equipment;

[0104] Auxiliary power supply module: performs voltage transformation on the 12V auxiliary power supply to provide power to modules such as microcontrollers;

[0105] Battery: Provides power to the RTC module in the high-frequency plasma surgical device after the external power supply is disconnected, and is used to store time information and other operating parameter information;

[0106] RTC module: Implements the internal clock timing of the high-frequency plasma surgical device;

[0107] Memory: Used to store various operating parameters, calibration parameters, and operating status information, usage count and time information of the instrument part of the high-frequency plasma surgical equipment; specifically, it can be an EEPROM memory, etc.

[0108] Prompt module: Used to provide audible prompts during the cutting and coagulation functions of the high-frequency plasma surgical equipment, and also to provide audible alarms when the high-frequency plasma surgical equipment malfunctions. Of course, audio prompts are only one method; other methods such as light prompts or combined prompts are also options.

[0109] Logic control module: Used to control the functions of auxiliary indicator lights, relays, and other modules inside the high-frequency plasma surgical equipment;

[0110] Instrument interface: An interface used to connect high-frequency plasma surgical equipment and surgical instruments. Signal transmission is achieved through a connector. The instrument interface also includes the connection of the negative electrode plate.

[0111] Surgical instruments: The cutting and coagulation signals of the high-frequency plasma surgical equipment are ultimately output to the surgical instruments. The high-frequency plasma surgical equipment forms a circuit between the surgical instruments, human tissue, and negative electrode plate, thereby realizing the cutting and coagulation functions.

[0112] Instrument communication module: used for data communication with surgical instruments, reading the serial number and type information of surgical instruments, and storing information such as the number of uses and time into the memory through the microcontroller;

[0113] Foot pedal or manual interface module: The high-frequency plasma surgical device receives operation commands and executes cutting or coagulation commands through the foot pedal or manual interface module;

[0114] Microcontroller: The control core of the high-frequency plasma surgical device. All logic functions, communication functions, data processing, and status monitoring are controlled through the microcontroller.

[0115] The high-frequency plasma surgical device in this embodiment differs from traditional high-frequency surgical devices in that it features low cutting and coagulation temperatures, effectively reducing tissue thermal damage and accelerating wound healing. In the power amplification section, traditional discrete MOSFET devices are no longer used. Traditional discrete MOSFET solutions are limited by switching frequencies and cannot further increase the operating frequency. This invention uses an RF power amplifier to amplify the cutting and coagulation signals, resulting in a higher operating frequency and enhanced skin effect compared to traditional high-frequency surgical devices, enabling more precise surgical operations.

[0116] This invention differs from traditional high-frequency surgical equipment by introducing an output power acquisition function into the step-up transformer section, providing flexible overload protection and further enhancing the safety of the equipment. The use of microcontroller control technology improves the equipment's digitalization and intelligence, thereby increasing control precision and flexibility.

[0117] Traditional high-frequency surgical equipment does not have a function for verifying the reusability of surgical instruments. When the present invention integrates communication and storage functions, it can realize the function of verifying the reusability of surgical instruments. This function can avoid cross-infection caused by accidental operation during the operation and improve the safety of the operation.

[0118] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A signal modulation circuit, characterized in that, Includes analog switches, slope control resistors, coupling capacitors, and variable gain operational amplifiers; The analog switch is driven by a low-frequency PWM signal. When the level of the low-frequency PWM signal is high, the analog switch connects the coupling capacitor to the high-frequency signal. When the level of the low-frequency PWM signal is low, the analog switch grounds the coupling capacitor through the slope control resistor. The variable gain operational amplifier amplifies the signal output from the coupling capacitor, and the control voltage of the variable gain operational amplifier is controlled by the target amplitude signal from the DAC.

2. The signal modulation circuit according to claim 1, characterized in that, The analog switch is a single-pole double-throw switch.

3. The signal modulation circuit according to claim 1, characterized in that, The values ​​of the slope control resistor and the coupling capacitor are determined based on the actual operating frequency of the high-frequency signal.

4. The signal modulation circuit according to claim 3, characterized in that, The value of the coupling capacitor is determined based on the actual operating frequency of the high-frequency signal, and the value of the slope control resistor is calculated based on the actual operating frequency of the high-frequency signal and the value of the coupling capacitor.

5. The signal modulation circuit according to claim 1, characterized in that, The calculation method for the slope control resistor includes: Determine the circuit parameters, including the actual operating frequency of the high-frequency signal, the coupling capacitance value, and the target discharge time; Establish an RC discharge model: in, u C This is the capacitor voltage, in volts (V). U is the discharge initiation voltage, which is determined by the phase of the high-frequency signal; R is the resistance value of the slope control resistor, in Ω; C is the coupling capacitance value, in F; t is the discharge time, in seconds; RC is the time constant, measured in seconds (s). The degree of voltage decay within the target discharge time is set, and the value of the time constant is calculated based on the degree of decay. The slope control resistor is calculated based on the time constant and the coupling capacitance value.

6. The signal modulation circuit according to claim 5, characterized in that, The method for calculating the slope control resistor also includes: The slope control resistor obtained from the calculation is adjusted, and the adjustment is made at least based on the error of the coupling capacitor, the error of the slope control resistor, and the internal resistance of the analog switch.

7. A high-frequency plasma surgical device, characterized in that, include: The signal modulation circuit as described in any one of claims 1 to 6 outputs a modulated signal; The driving circuit performs primary power amplification on the modulation signal; The radio frequency power amplifier circuit performs a secondary power amplification on the modulated signal that has already undergone primary power amplification; A step-up transformer boosts the voltage of the modulated signal that has undergone secondary power amplification so that the output signal matches the impedance of the human body. The driving section includes a high-speed operational amplifier, a balancing resistor, a gain control resistor, and a feedback resistor. The non-inverting input of the high-speed operational amplifier is connected to the output of the variable gain operational amplifier of the signal modulation circuit through the balancing resistor, and the inverting input is grounded through the gain control resistor. The output of the high-speed operational amplifier is connected to the inverting input through the feedback resistor.

8. The high-frequency plasma surgical device according to claim 7, characterized in that, The step-up transformer undergoes at least two stages of voltage boosting.

9. The high-frequency plasma surgical device according to claim 7, characterized in that, Also includes: The output power sampling module collects and processes the operating signal of the step-up transformer, calculates the current output power of the output signal, and obtains the calculation result. The output threshold setting module sets the overload protection threshold according to the output requirements of the high-frequency plasma surgical equipment. The safety logic module determines the overload occurrence time by comparing the calculation result with the overload protection threshold, and generates an overload protection signal when an overload occurs. The overload protection signal is used to control the signal modulation circuit and the drive circuit to stop working.

10. The high-frequency plasma surgical device according to claim 9, characterized in that, The security logic module is triggered by the calculation result; After being triggered, the safety logic module then compares the calculation result with the overload protection threshold.

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