Gain adjustment module, control method and implantable neural stimulation system

Abstract

The present invention discloses a gain adjustment module, a control method and an implantable neural stimulation system. The gain adjustment module includes a gain control unit and an analog-to-digital conversion unit connected to the gain control unit. The gain control unit is used to obtain an initial output signal according to a preset gain and a received initial input signal, and to adjust the gain according to the numerical value of the initial output signal to obtain a target gain. The gain control unit obtains a target output signal according to the target gain and the initial input signal, and the analog-to-digital conversion unit converts the target output signal into a digital signal. The gain adjustment unit of the present invention can adjust the gain according to the numerical value of the initial output signal to achieve automatic control of the gain, so that the target gain finally obtained can adapt to the current electroencephalogram signal, so that the amplitude of the target output signal finally output to the analog-to-digital conversion unit is kept within a certain range, thereby improving the accuracy of the analog-to-digital conversion.

Description

Technical Field

[0001] The present invention relates to the field of implantable medical treatment, and in particular to a gain adjustment module, a control method and an implantable neural stimulation system. Background Art

[0002] In recent years, implantable medical systems have been increasingly widely used in clinical medicine, usually including implantable neural stimulation systems (including deep brain stimulation system DBS, implantable cerebral cortical stimulation system CNS, implantable spinal cord stimulation system SCS, implantable sacral nerve stimulation system SNS, implantable vagus nerve stimulation system VNS, etc.), implantable cardiac stimulation systems (commonly known as pacemakers), implantable drug infusion systems (IDDS), etc.

[0003] In implantable medical systems, neurostimulation systems can effectively control the symptoms of functional neurological and psychiatric diseases by chronically electrically stimulating target nerves.

[0004] The frequency and amplitude of the target nerve signal can reflect the condition of the neurological disease. By reading the target nerve signal, we can judge the condition and take optimized treatment methods, and we can also objectively judge the therapeutic effect of the nerve stimulation system.

[0005] The target neural EEG signal acquisition needs to first amplify the EEG signal through the gain amplifier unit, then convert the EEG signal into a digital signal through the analog-to-digital conversion unit, and finally transmit the digital signal through wireless communication.

[0006] In actual application, the amplitudes of EEG signals vary greatly. If the gain amplifier unit amplifies the EEG signal by a fixed gain multiple, then the amplified EEG signal received by the analog-to-digital conversion unit may have an amplitude that is too large or too small, resulting in inaccurate analog-to-digital conversion. Therefore, it is necessary to adjust the gain multiple of the gain amplifier unit to adapt to EEG signals of different amplitudes. Summary of the invention

[0007] The object of the present invention is to provide a gain adjustment module, a control method and an implantable neural stimulation system.

[0008] To achieve one of the above-mentioned purposes of the invention, one embodiment of the present invention provides a gain adjustment module, including a gain control unit and an analog-to-digital conversion unit connected to the gain control unit, the gain control unit is used to obtain an initial output signal according to a preset gain and a received initial input signal, and to adjust the gain according to the numerical value of the initial output signal to obtain a target gain, and the gain control unit obtains a target output signal according to the target gain and the initial input signal, and the analog-to-digital conversion unit converts the target output signal into a digital signal.

[0009] As a further improvement of one embodiment of the present invention, the gain control unit includes a gain operational amplifier unit, a peak detection unit, a comparison unit, a coarse adjustment unit and a fine adjustment unit. The gain operational amplifier unit and the peak detection unit are respectively used to obtain an initial output signal and an initial peak voltage to complete a peak acquisition cycle. The comparison unit is used to determine whether the initial peak voltage meets a preset condition. If so, the fine adjustment process is entered. The fine adjustment unit obtains the fine adjustment multiple and transmits it to the gain operational amplifier unit, and the gain operational amplifier unit uses the product of the fine adjustment multiple and the preset gain as the target gain; if not, the coarse adjustment process is entered. The gain operational amplifier unit obtains the coarse adjustment multiple provided by the coarse adjustment unit and replaces the preset gain with the product of the coarse adjustment multiple and the preset gain. The gain operational amplifier unit and the peak detection unit obtain an intermediate peak voltage according to the peak acquisition cycle, and when the intermediate peak voltage meets the preset condition, the fine adjustment process is entered. The gain operational amplifier unit uses the product of the coarse adjustment multiple, the fine adjustment multiple and the preset gain as the target gain.

[0010] As a further improvement of one embodiment of the present invention, the comparison unit is used to determine whether the initial peak voltage is within a preset range. If so, the fine-tuning process is entered. The fine-tuning unit obtains a fine-tuning multiple based on the current peak voltage and transmits it to the gain amplifier unit. The fine-tuning multiple is the multiple between the current peak voltage and the target value. The gain amplifier unit uses the product of the fine-tuning multiple and the preset gain as the target gain; if not, the coarse-tuning process is entered.

[0011] As a further improvement of an embodiment of the present invention, the fine adjustment unit includes a reference voltage unit and a comparator, the comparator includes a first input terminal, a second input terminal and a first output terminal, the first input terminal is connected to the peak detection unit, and the second input terminal is connected to the reference voltage unit, wherein the peak detection unit is used to output the current peak voltage, and the reference voltage unit is used to output a variable reference voltage, and when the comparator output flips, the fine adjustment unit uses the current variable reference voltage value as the current peak voltage.

[0012] As a further improvement of one embodiment of the present invention, the reference voltage unit includes a first amplifier and a channel selection unit, the first amplifier includes a third input terminal, a fourth input terminal and a second output terminal, the third input terminal is connected to a first fixed reference voltage, the second output terminal is connected to the channel selection unit, and the second output terminal is provided with a plurality of series resistors, the fourth input terminal is connected to different regions of the plurality of series resistors to enable the first amplifier to output a variable voltage, and the channel selection unit selects the variable voltage and outputs the variable voltage as the variable reference voltage.

[0013] As a further improvement of an embodiment of the present invention, the comparison unit is used to determine whether the initial peak voltage is less than a preset value. If so, the fine-tuning process is entered, and the comparison unit continues to determine whether the difference between the initial peak voltage and the preset value is less than a preset threshold. If it is not less than the preset threshold, the gain amplifier unit obtains the fine-tuning multiple provided by the fine-tuning unit and replaces the preset gain with the product of the fine-tuning multiple and the preset gain, and the gain amplifier unit and the peak detection unit obtain a temporary peak voltage according to a peak acquisition cycle, and repeat the peak acquisition cycle until the difference between the obtained temporary peak voltage and the preset value is less than the preset threshold. If it is less than the preset threshold, the fine-tuning unit obtains the current fine-tuning multiple and transmits it to the gain amplifier unit, and the gain amplifier unit uses the product of the current fine-tuning multiple and the preset gain as the target gain; if not, the coarse adjustment process is entered.

[0014] As a further improvement of one embodiment of the present invention, the coarse adjustment multiple includes several optional coarse adjustment multiples, the fine adjustment multiple includes several optional fine adjustment multiples, and the several optional coarse adjustment multiples include a first-level coarse adjustment multiple, a second-level coarse adjustment multiple and a third-level coarse adjustment multiple that can be selected in sequence.

[0015] As a further improvement of an embodiment of the present invention, the fine-tuning multiple is achieved by a second amplifier, the second amplifier includes a fifth input terminal, a sixth input terminal and a third output terminal, the fifth input terminal includes a fixed resistor and a variable resistor, one end of the variable resistor is connected between the fixed resistor and the fifth input terminal, and the other end is connected to the third output terminal, the sixth input terminal is connected to a second fixed reference voltage, and the third output terminal is connected to the gain operational amplifier unit, wherein the fine-tuning multiple is the ratio of the variable resistor to the fixed resistor.

[0016] As a further improvement of an implementation manner of the present invention, the preset gain is the maximum gain of the gain adjustment module.

[0017] As a further improvement of an embodiment of the present invention, the peak detection unit includes a first switch, a diode, a first resistor, a first capacitor set to ground, a second resistor set to ground and connected in series, and a second switch connected in sequence, wherein the first switch is used to control the input of the peak detection unit, the second switch is used for resetting, the second resistor is used to limit the discharge current, the diode cooperates with the first resistor and the first capacitor to realize unidirectional storage of multiple input voltages, and then obtains the peak voltage through the multiple input voltages and uses it as the output of the peak detection unit.

[0018] As a further improvement of one embodiment of the present invention, the peak detection unit includes a third amplifier, the third amplifier includes a seventh input terminal, an eighth input terminal and a fourth output terminal, the seventh input terminal is provided with a third resistor and a second capacitor, the eighth input terminal is connected to the fourth output terminal and includes a fourth resistor, a third switch and a third capacitor that are grounded and connected in series, the fourth output terminal is provided with a transistor, one end of the transistor is connected to a power supply voltage, and the other end of the transistor is connected to the third capacitor, wherein the third resistor and the second capacitor are used for filtering, the third switch is used for resetting, and the transistor is used to generate a bias current, and a peak voltage is obtained by gradually increasing several input voltages input through the seventh input terminal, and the fourth output terminal uses the obtained peak voltage as the output of the peak detection unit.

[0019] To achieve one of the above-mentioned purposes of the invention, one embodiment of the present invention provides an implantable neural stimulation system, comprising a gain adjustment module, a stimulation electrode and a terminal device as described in any one of the above technical solutions, wherein the stimulation electrode is used to obtain an electroencephalogram signal as an initial input signal of the gain adjustment module, and the gain adjustment module transmits the converted digital signal to the terminal device.

[0020] To achieve one of the above objects of the invention, an embodiment of the present invention provides a gain control method, comprising the steps of:

[0021] Obtaining an initial input signal;

[0022] Acquire an initial output signal according to the initial input signal and a preset gain;

[0023] Adjusting the gain according to the value of the initial output signal to obtain a target gain;

[0024] Acquire a target output signal according to the initial input signal and the target gain;

[0025] The target output signal is converted into a digital signal.

[0026] As a further improvement of an embodiment of the present invention, the step of “adjusting the gain according to the value of the initial output signal to obtain the target gain” specifically includes:

[0027] Obtaining an initial peak voltage of the initial output signal;

[0028] Determining whether the initial peak voltage meets a preset condition;

[0029] If yes, the fine-tuning process is started to obtain the fine-tuning multiple, and the product of the fine-tuning multiple and the preset gain is used as the target gain;

[0030] If not, the coarse adjustment process is entered to obtain the coarse adjustment multiple, replace the preset gain with the product of the coarse adjustment multiple and the preset gain and obtain the corresponding intermediate peak voltage, and the fine adjustment process is entered when the intermediate peak voltage meets the preset conditions.

[0031] As a further improvement of an embodiment of the present invention, the step of "determining whether the initial peak voltage meets the preset conditions; if so, entering the fine adjustment process, and taking the product of the fine adjustment factor and the preset gain as the target gain" specifically includes:

[0032] Determining whether the initial peak voltage is within a preset range;

[0033] If so, the fine-tuning process is entered to obtain the current peak voltage and obtain the fine-tuning multiple according to the current peak voltage. The product of the fine-tuning multiple and the preset gain is used as the target gain. The fine-tuning multiple is the multiple between the current peak voltage and the target value.

[0034] As a further improvement of an embodiment of the present invention, the step of "determining whether the initial peak voltage meets the preset conditions; if so, entering the fine adjustment process, and taking the product of the fine adjustment factor and the preset gain as the target gain" specifically includes:

[0035] Determining whether the initial peak voltage is less than a preset value;

[0036] If so, the fine-tuning process is entered to determine whether the difference between the initial peak voltage and the preset value is less than the preset threshold. If it is not less than the preset threshold, the fine-tuning factor is obtained, the preset gain is replaced by the product of the fine-tuning factor and the preset gain, and the corresponding temporary peak voltage is obtained until the difference between the temporary peak voltage and the preset value is less than the preset threshold. If it is less than the preset threshold, the product of the current fine-tuning factor and the preset gain is used as the target gain.

[0037] Compared with the prior art, the beneficial effect of the present invention lies in that the gain adjustment unit of one embodiment of the present invention can adjust the gain according to the numerical value of the initial output signal to achieve automatic control of the gain, so that the target gain finally obtained can adapt to the current EEG signal, thereby making the amplitude of the target output signal finally output to the analog-to-digital conversion unit remain within a certain range, thereby improving the accuracy of the analog-to-digital conversion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic diagram of an implantable neural stimulation system according to an embodiment of the present invention;

[0039] Figure 2 It is a schematic diagram of the cooperation between the gain adjustment module, the stimulation electrode and the terminal device according to one embodiment of the present invention;

[0040] Figure 3is a schematic diagram of a gain control unit according to a first embodiment of the present invention;

[0041] Figure 4 is a schematic diagram of a fine adjustment unit according to a first embodiment of the present invention;

[0042] Figure 5 is a circuit diagram of a reference voltage unit according to a first embodiment of the present invention;

[0043] Figure 6 is a circuit diagram of a peak detection unit according to a first embodiment of the present invention;

[0044] Figure 7 is a circuit diagram of another embodiment of the peak detection unit of the first embodiment of the present invention;

[0045] Figure 8 is a schematic diagram of the operation steps of the gain adjustment module at different times of the first embodiment of the present invention;

[0046] Fig. 9 is a schematic diagram of a gain control unit according to a second embodiment of the present invention;

[0047] Figures 10 to 12 is a schematic diagram of a specific adjustment process of a gain control unit according to a second embodiment of the present invention;

[0048] Fig.13 is a schematic diagram of obtaining the fine adjustment multiple according to the second embodiment of the present invention;

[0049] Fig.14 yes Fig.13 In the Rv circuit diagram;

[0050] Fig.15 It is a step diagram of a gain control method according to one embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0052] Ginseng Figure 1 , one embodiment of the present invention provides an implantable neural stimulation system.

[0053] An implantable neural stimulation system generally includes the following components: a plurality of stimulation electrodes 200 (here taking left brain electrodes and right brain electrodes as examples), electrode wires 300, extension wires 500, a pulse generator 400 and a terminal device 600.

[0054] Taking the deep brain stimulation system DBS as an example, the pulse generator 400 transmits electrical pulses to the STN (Subthalamic Nucleus) nucleus of the brain through the extension wire 500, the electrode wire 300 and the stimulation electrode 200 to achieve the purpose of treating Parkinson's disease and other diseases.

[0055] Taking the program controller as an example, the terminal device 600 is used to adjust the stimulation parameters of the pulse generator 400. The stimulation parameters include pulse amplitude, pulse width (i.e., pulse width) and pulse frequency, etc. It can be understood that the terminal device 600 can also be other devices, such as a display device, etc., which can be determined according to actual conditions.

[0056] Combination Figure 2 The implantable neural stimulation system also includes a gain adjustment module 100.

[0057] The stimulation electrode 200 is used to obtain an electroencephalogram signal and transmit the electroencephalogram signal as an input signal to the gain adjustment module 100 .

[0058] It should be noted that the EEG signal acquired by the stimulation electrode 200 may be an EEG signal in a stimulated state or an EEG signal in a non-stimulated state.

[0059] The gain adjustment module 100 adjusts the gain according to the input signal and obtains the adjusted output signal, and the gain adjustment module 100 converts the output signal into a digital signal and transmits it to the terminal device 600 .

[0060] Of course, it is also possible to transmit the information to other components instead of the terminal device 600 .

[0061] The gain adjustment module 100 according to one embodiment of the present invention is described in detail below.

[0062] Continue to participate Figure 2 The gain adjustment module 100 includes a gain control unit 10 and an analog-to-digital conversion unit 20 .

[0063] The analog-to-digital conversion unit 20 is electrically connected to the gain control unit 10 .

[0064] The gain control unit 10 is used for obtaining an initial output signal Vout according to a preset gain Ao and a received initial input signal Vin.

[0065] The initial output signal Vout is a signal obtained by amplifying the input signal Vin according to a preset gain Ao.

[0066] The gain control unit 10 is then used to adjust the gain according to the value of the initial output signal Vout to obtain the target gain At, and the gain control unit 10 obtains the target output signal Vt according to the target gain At and the initial input signal Vin.

[0067] The analog-to-digital conversion unit 20 converts the target output signal Vt into a digital signal, and then transmits the digital signal to the terminal device 600 through wireless communication or limited communication. The terminal device 600 can intuitively judge the condition and take optimized treatment methods through the digital signal, and can also objectively judge the treatment effect of the implantable neural stimulation system.

[0068] The gain adjustment module 100 of this embodiment can adjust the gain according to the value of the initial output signal Vout to achieve automatic control of the gain, so that the target gain At finally obtained can adapt to the current EEG signal, thereby making the amplitude of the target output signal Vt finally output to the analog-to-digital conversion unit 20 remain within a certain range, thereby improving the accuracy of the analog-to-digital conversion.

[0069] Combination Figure 3 , is a schematic diagram of a gain control unit 10 according to an embodiment of the present invention.

[0070] The gain control unit 10 includes a gain amplifier unit 11 , a peak detection unit 12 , a comparison unit 13 , a coarse adjustment unit 14 and a fine adjustment unit 15 .

[0071] The gain amplifier unit 11 is a low noise gain amplifier unit.

[0072] The gain amplifier unit 11 is used for obtaining an initial output signal Vout according to a preset gain Ao and a received initial input signal Vin.

[0073] The peak detection unit 12 is located between the gain amplifier unit 11 and the comparison unit 13 .

[0074] The peak detection unit 12 is used to obtain an initial peak voltage Vpeak0 of the initial output signal Vout.

[0075] Here, the gain amplifier unit 11 and the peak detection unit 12 are used to obtain the initial output signal Vout and the initial peak voltage Vpeak0 respectively to complete a peak acquisition cycle.

[0076] One end of the coarse adjustment unit 14 and the fine adjustment unit 15 are connected to the comparison unit 13 , and the other end is connected to the gain amplifier unit 11 .

[0077] The comparison unit 13 is used to determine whether the initial peak voltage Vpeak0 meets a preset condition.

[0078] If yes, the fine adjustment process is started, the fine adjustment unit 15 obtains the fine adjustment multiple An and transmits it to the gain amplifier unit 11, and the gain amplifier unit 11 uses the product of the fine adjustment multiple An and the preset gain Ao as the target gain At (At=Ao*An).

[0079] If not, the coarse adjustment process is entered, and the gain amplifier unit 11 obtains the coarse adjustment multiple Am provided by the coarse adjustment unit 14 and replaces the preset gain Ao with the product of the coarse adjustment multiple Am and the preset gain Ao, and the gain amplifier unit 11 and the peak detection unit 12 obtain the intermediate peak voltage Vpeak1 according to the peak acquisition cycle, and when the intermediate peak voltage Vpeak1 meets the preset conditions, the fine adjustment process is entered, and the gain amplifier unit 11 uses the product of the coarse adjustment multiple Am, the fine adjustment multiple An and the preset gain Ao as the target gain At (At=Ao*An*Am).

[0080] The gain control unit 10 of this embodiment has multiple schemes. Figure 3 and Figure 4 Two specific embodiments of the gain control unit 10 are illustrated, but the present invention is not limited thereto.

[0081] Combination Figure 3 , is a schematic diagram of a gain control unit 10 of the first specific embodiment.

[0082] The comparison unit 13 is used to determine whether the initial peak voltage Vpeak0 is within a preset range.

[0083] If so, the fine-tuning process begins. The fine-tuning unit 15 obtains the fine-tuning multiple An based on the current peak voltage Vpeak and transmits it to the gain amplifier unit 11. The fine-tuning multiple An is the multiple between the current peak voltage Vpeak and the target value. The gain amplifier unit 11 uses the product of the fine-tuning multiple An and the preset gain Ao as the target gain At (At=Ao*An).

[0084] If not, the coarse adjustment process is entered, and the gain amplifier unit 11 obtains the coarse adjustment multiple Am provided by the coarse adjustment unit 14 and replaces the preset gain Ao with the product of the coarse adjustment multiple Am and the preset gain Ao, and the gain amplifier unit 11 and the peak detection unit 12 obtain the intermediate peak voltage Vpeak1 according to the peak acquisition cycle, and when the intermediate peak voltage Vpeak1 meets the preset conditions, the fine adjustment process is entered, and the gain amplifier unit 11 uses the product of the coarse adjustment multiple Am, the fine adjustment multiple An and the preset gain Ao as the target gain At (At=Ao*An*Am).

[0085] Here, the target value may be a fixed value within a preset range.

[0086] The current peak voltage Vpeak is the actual peak voltage of the actual output EEG signal, and the intermediate peak voltage Vpeak1 is the peak voltage obtained according to the peak acquisition cycle. That is to say, when the initial peak voltage Vpeak0 is not within the preset range, the intermediate peak voltage Vpeak1 is repeatedly obtained according to the peak acquisition cycle, that is, the product of the coarse adjustment factor Am and the preset gain Ao is repeatedly replaced by the preset gain Ao (that is, the product of the coarse adjustment factor Am and the preset gain Ao is used as the new gain), and the intermediate output signal Vout1 is obtained according to the new gain (Am*Ao) and the initial input signal Vin, and the peak detection unit 12 obtains the intermediate peak voltage Vpeak1 according to the intermediate output signal Vout1.

[0087] It should be noted that the coarse adjustment multiple Am in “repeatedly replacing the preset gain Ao with the product of the coarse adjustment multiple Am and the preset gain Ao” changes continuously. For example, the coarse adjustment multiple Am in the second peak acquisition cycle is four times, and the coarse adjustment multiple Am in the third peak acquisition cycle is also four times. Then, the new gain in the peak acquisition cycle at this time is the product of the coarse adjustment multiple Am in the second peak acquisition cycle, the coarse adjustment multiple Am in the third peak acquisition cycle and the preset gain Ao.

[0088] In addition, it should be noted that "the new gain is the product of the coarse adjustment multiple Am in the second peak acquisition cycle, the coarse adjustment multiple Am in the third peak acquisition cycle and the preset gain Ao" actually means: when the coarse adjustment process is to increase the gain, the new gain is Ao*4*4, when the coarse adjustment process is to reduce the gain, the new gain is Ao*1 / 4*1 / 4. That is to say, for the convenience of explanation, the new gain is defined as the product of the coarse adjustment multiple and the preset gain Ao, but in actual operation, it can also be the product of the inverse of the coarse adjustment multiple and the preset gain Ao, which needs to be determined according to the actual situation. The same applies to the coarse adjustment multiples and fine adjustment multiples of other parts.

[0089] Specific, combined Figure 4 The fine tuning unit 15 includes a reference voltage unit 321 and a comparator 322 .

[0090] The comparator 322 includes a first input terminal 3221 , a second input terminal 3222 and a first output terminal 3223 .

[0091] The first input terminal 3221 is connected to the peak detection unit 12 .

[0092] The second input terminal 3222 is connected to the reference voltage unit 321 .

[0093] The peak detection unit 12 is used to output the current peak voltage Vpeak, the reference voltage unit 321 is used to output the variable reference voltage, and when the output of the comparator 322 is reversed, the fine adjustment unit 15 uses the current variable reference voltage as the current peak voltage Vpeak.

[0094] That is to say, the reference voltage unit 321 continuously generates variable reference voltages of various amplitudes, compares the variable reference voltage with the current peak voltage Vpeak, and finally confirms the value of the current peak voltage Vpeak through the output result (0 or 1) of the first output terminal 3223, that is, when the first output terminal 3223 changes from output 0 to output 1, the current variable reference voltage is close to the actual current peak voltage Vpeak, and the current variable reference voltage can be used as the current peak voltage Vpeak.

[0095] Combination Figure 5 , is a circuit diagram of the reference voltage unit 321.

[0096] The reference voltage unit 321 includes a first amplifier 3211 and a channel selection unit 3212 .

[0097] The first amplifier 3211 includes a third input terminal 32111 , a fourth input terminal 32112 , and a second output terminal 32113 .

[0098] The third input terminal 32111 is connected to the first fixed reference voltage Vref1, the second output terminal 32113 is connected to the channel selection unit 3212, and the second output terminal 32113 is provided with a plurality of series resistors Rx, the fourth input terminal 32112 is connected to different regions of the plurality of series resistors Rx to enable the first amplifier 3211 to output a variable voltage, the channel selection unit 3212 selects the variable voltage and outputs the variable voltage as a variable reference voltage, that is, at this time, the output terminal of the channel selection unit 3212 is connected to the second input terminal 3222 of the comparator 322.

[0099] Here, the first fixed reference voltage Vref1 is 1.2V, and a variable voltage of 0 to 2V is generated through the operational amplifier action of the first amplifier 3211. The change interval of the variable voltage is 20mV. After cooperating with a 6-bit (64-channel) channel selection unit 3212, the variable reference voltage can be selectively output to the second input terminal 3222 of the comparator 322.

[0100] In this embodiment, the gain adjustment process includes a coarse adjustment process (a wide range adjustment process with a larger multiple) and a fine adjustment process (a small range adjustment process with a smaller multiple). When the initial peak voltage Vpeak0 is not within the preset range and meets the conditions after a limited number of coarse adjustment processes, the fine adjustment process is entered. At this time, the final gain adjustment multiple is the product of the coarse adjustment multiple Am and the fine adjustment multiple An. When the initial peak voltage Vpeak0 is within the preset range, the final gain adjustment multiple is the fine adjustment multiple An.

[0101] In addition, the coarse adjustment multiple Am of this embodiment can be a fixed multiple, and the fine adjustment multiple An can be obtained through the gradual approximation process of the variable reference voltage. The process of obtaining the gain multiple is convenient and fast, realizing automatic control of the variable gain and greatly improving the gain output efficiency.

[0102] It should be noted that, in this embodiment, the coarse adjustment multiple Am includes a plurality of optional coarse adjustment multiples, and the plurality of optional coarse adjustment multiples may be fixed in number and fixed in multiple, but is not limited thereto.

[0103] Taking the coarse adjustment multiple Am including three levels of coarse adjustment multiples as an example, when the initial peak voltage Vpeak0 passes through the first level of coarse adjustment multiple Am in sequence 1 、Second level coarse adjustment multiple Am 2 And the third level coarse adjustment multiple Am 3 When the intermediate peak voltage Vpeak1 obtained after the coarse adjustment is still not within the preset range, the preset gain Ao is directly updated to the maximum adjustable gain multiple, and the target output signal Vt is obtained according to the maximum adjustable gain multiple and the initial input signal Vin.

[0104] In this embodiment, combined with Figure 6 and Figure 7 , are circuit diagrams of two specific embodiments of the peak detection unit 12.

[0105] Combination Figure 6 In one embodiment, the peak detection unit 12a includes a first switch S1, a diode D1, a first resistor R1, a first capacitor C1 connected to the ground, a second resistor R2 connected to the ground and in series, and a second switch S2.

[0106] Among them, the first switch S1 is used to control the input of the peak detection unit 12a, the second switch S2 is used for resetting, the second resistor R2 is used to limit the discharge current, the diode D1 cooperates with the first resistor R1 and the first electrode C1 to realize unidirectional storage of several input voltages, and then obtains the peak voltage through the several input voltages and serves as the output of the peak detection unit 12a.

[0107] Here, the output signal transmitted from the gain amplifier unit 11 to the peak detection unit 12a includes multiple voltage values. For example, the output signal is a sine wave. At this time, since the diode D1 is a unidirectional conductive structure, combined with the filtering and storage functions of the first resistor R1 and the first capacitor C1, the peak voltage can be obtained.

[0108] The first resistor R1 is 40 MΩ, the first capacitor C1 is 30 pF, and the second resistor R2 is 20 kΩ. The advantage of the peak detection unit 12 a of this embodiment is that the components are all passive devices, and there is basically no power loss.

[0109] Combination Figure 7 In another embodiment, the peak detection unit 12b includes a third amplifier 311b.

[0110] The third amplifier 311b includes a seventh input terminal 3111b, an eighth input terminal 3112b and a fourth output terminal 3113b.

[0111] The seventh input terminal 3111b is provided with a third resistor R3 and a second capacitor C2, the eighth input terminal 3112b is connected to the fourth output terminal 3113b and includes a fourth resistor R4, a third switch S3 and a third capacitor C3 which are grounded and connected in series, and the fourth output terminal 3113b is provided with a transistor T, one end of the transistor T is connected to the power supply voltage Vcc, and the other end of the transistor T is connected to the third capacitor C3.

[0112] The third resistor R3 and the second capacitor C2 are used for filtering, the third switch S3 is used for resetting, and the transistor T is used to generate a bias current Ibias. The bias current Ibias can control the voltage change efficiency of the third capacitor C3. The peak voltage is obtained by inputting a plurality of gradually increasing input voltages through the seventh input terminal 3111b, and the fourth output terminal 3113b uses the obtained peak voltage as the output of the peak detection unit 12b.

[0113] Here, the output signal transmitted from the gain amplifier unit 11 to the peak detection unit 12b includes multiple voltage values. For example, the output signal is a sine wave. At this time, since the circuit structure only charges but does not discharge, combined with filtering and storage, the peak voltage can be obtained.

[0114] The advantage of the peak detection unit 12 b of this embodiment is that the obtained peak voltage can accurately reflect the output of the gain amplifier unit 11 and is not affected by process deviations.

[0115] In this embodiment, combined with Figure 8 , illustrating the operation steps of the gain adjustment module 100 at different times.

[0116] Since the amplitude of the EEG signal is uncertain, the peak detection unit 12 needs to work continuously for a period of time to obtain the peak voltage. Here, taking the single working time of the peak detection unit 12 as 1s as an example, that is, the time duration for the peak detection unit 12 to obtain a peak voltage is 1s.

[0117] Since the current peak voltage Vpeak is obtained by gradual approximation, the gain of the gain amplifier unit 11 needs to be gradually adjusted. Each time the gain amplifier unit 11 adjusts the gain, the peak value is resampled and approximated again.

[0118] Here, before each peak value sampling, a peak voltage reset process needs to be performed, and the duration of each reset is 2 seconds as an example.

[0119] It can be seen that the shortest time to obtain the target gain At is 3s, that is, the peak detection unit 12 obtains the target gain At after one processing. At this time, the time to obtain the target gain At is the sum of the reset time 2s and the single working time of the peak detection unit 12 of 1s.

[0120] The single gain adjustment time of the gain adjustment module 100 does not exceed 12 seconds.

[0121] That is to say, four approximation processes are performed at this time, and the peak detection unit 12 performs four processings (ie, three coarse adjustment processes plus one fine adjustment process).

[0122] The gain adjustment module 100 also includes a clock unit, the frequency of which is 1 kHz, and after frequency division, the maximum timer can be 15 seconds.

[0123] In addition, it can be seen that when the peak voltage after three coarse adjustment processes is still not within the preset range, if the peak voltage at this time is less than the minimum value of the preset range, the gain is directly set to the maximum value; if the peak voltage at this time is greater than the maximum value of the preset range, the gain is directly set to the minimum value.

[0124] Combination Fig. 9 , is a schematic diagram of a gain control unit 10 ′ of the second specific embodiment.

[0125] The comparison unit 13 ′ is used to determine whether the initial peak voltage Vpeak0 ′ is less than a preset value.

[0126] If so, the fine-tuning process is entered, and the comparison unit 13' continues to determine whether the difference between the initial peak voltage Vpeak0' and the preset value is less than the preset threshold value. If it is not less than the preset threshold value, the gain amplifier unit 11' obtains the fine-tuning multiple An' provided by the fine-tuning unit 15' and replaces the preset gain Ao' with the product of the fine-tuning multiple An' and the preset gain Ao', and the gain amplifier unit 11' and the peak detection unit 12' obtain the temporary peak voltage Vpeak2' according to the peak acquisition cycle, and repeat the peak acquisition cycle until the difference between the obtained temporary peak voltage Vpeak2' and the preset value is less than the preset threshold value. If it is less than the preset threshold value, the fine-tuning unit 15' obtains the current fine-tuning multiple An' and transmits it to the gain amplifier unit 11', and the gain amplifier unit 11' uses the product of the current fine-tuning multiple An' and the preset gain Ao' as the target gain At' (At=Ao'*An').

[0127] If not, the coarse adjustment process is entered, and the gain amplifier unit 11' obtains the coarse adjustment multiple Am' provided by the coarse adjustment unit 14' and replaces the preset gain Ao' with the product of the coarse adjustment multiple Am' and the preset gain Ao', and the gain amplifier unit 11' and the peak detection unit 12' obtain the intermediate peak voltage Vpeak1' according to the peak acquisition cycle, and when the intermediate peak voltage Vpeak1' is less than the preset value, the fine adjustment process is entered, and the gain amplifier unit 11' uses the product of the coarse adjustment multiple Am', the fine adjustment multiple An' and the preset gain Ao' as the target gain At' (At'=Ao'*An'*Am').

[0128] Here, the intermediate peak voltage Vpeak1' is the peak voltage obtained according to the peak acquisition cycle, that is, when the initial peak voltage Vpeak0 is not less than the preset value, the intermediate peak voltage Vpeak1' is repeatedly obtained according to the peak acquisition cycle, that is, the product of the coarse adjustment multiple Am' and the preset gain Ao' is repeatedly replaced by the preset gain Ao', and the intermediate output signal Vout1' is obtained according to the new gain and the initial input signal Vin', and the peak detection unit 12' obtains the intermediate peak voltage Vpeak1' according to the intermediate output signal Vout1'.

[0129] It should be noted that the coarse adjustment multiple Am' in "repeatedly replacing the preset gain Ao' with the product of the coarse adjustment multiple Am' and the preset gain Ao'" changes continuously. For example, the coarse adjustment multiple Am' in the second peak acquisition cycle is four times, and the coarse adjustment multiple Am' in the third peak acquisition cycle is two times. Then, the new gain in the third peak acquisition cycle is the quotient of the preset gain Ao' and the coarse adjustment multiple Am' in the second peak acquisition cycle and the coarse adjustment multiple Am' in the third peak acquisition cycle (new gain = Ao'*1 / 4*1 / 2).

[0130] Similarly, the temporary peak voltage Vpeak2' is the peak voltage obtained according to the peak acquisition cycle, that is, when the difference between the initial peak voltage Vpeak0' and the preset value is not less than the preset threshold value, the temporary peak voltage Vpeak2' is repeatedly obtained according to the peak acquisition cycle, that is, the product of the fine-tuning multiple An' and the preset gain Ao' is repeatedly replaced by the preset gain Ao', and the temporary output signal Vout2' is obtained according to the new gain and the initial input signal Vin', and the peak detection unit 12' obtains the temporary peak voltage Vpeak2' according to the temporary output signal Vout2'.

[0131] It should be noted that the fine adjustment multiple An' in "repeatedly replacing the preset gain Ao' with the product of the fine adjustment multiple An' and the preset gain Ao'" changes independently. For example, the fine adjustment multiple An' in the second peak acquisition cycle is 1.25, and the fine adjustment multiple An' in the third peak acquisition cycle is 1.5. Then, the new gain in the second peak acquisition cycle is the product of the fine adjustment multiple An' in the second peak acquisition cycle and the preset gain Ao' (new gain = Ao'*1.25), and the new gain in the third peak acquisition cycle is the product of the fine adjustment multiple An' in the third peak acquisition cycle and the preset gain Ao' (new gain = Ao'*1.5).

[0132] Specific, combined Figures 10 to 12 , which is a schematic diagram of a specific adjustment process of the gain control unit 10' of this embodiment.

[0133] Here, it is assumed that the coarse adjustment multiple Am' includes a first coarse adjustment multiple Am1', a second coarse adjustment multiple Am2' and a third coarse adjustment multiple Am3' which can be selected in sequence. The first coarse adjustment multiple Am1' is four times, and the second coarse adjustment multiple Am2' and the third coarse adjustment multiple Am3' are both two times.

[0134] The maximum selectable fine adjustment multiple among the fine adjustment multiples An' is not greater than two times.

[0135] It can be understood that the final target gain At' is the integration of the three-level adjustment results. Of course, according to the actual situation, the target gain At' can be obtained after only one-level adjustment, or after one-level adjustment, two-level adjustment and three-level adjustment.

[0136] That is to say, the gain adjustment process includes a coarse adjustment process (a wide-range adjustment process with a larger multiple) and a fine adjustment process (a small-range adjustment process with a smaller multiple). When the initial peak voltage Vpeak0' is greater than the preset value and meets the conditions after a limited number of coarse adjustment processes, the fine adjustment process is entered. At this time, the final gain adjustment multiple is the product of the coarse adjustment multiple Am' and the fine adjustment multiple An'. When the initial peak voltage Vpeak0' is not greater than the preset value, the final gain adjustment multiple is the fine adjustment multiple An'.

[0137] In addition, the coarse adjustment multiple Am' in this embodiment can be a fixed multiple, and the fine adjustment multiple An' is obtained through a step-by-step approximation process between the temporary peak voltage Vpeak2' and the preset value, and the final obtained gain multiple is closer to the preset value.

[0138] It should be noted that in this embodiment, the coarse adjustment multiple Am' includes several optional coarse adjustment multiples, and the several optional coarse adjustment multiples are fixed in number and multiples. When the initial peak voltage Vpeak0' passes through the first level coarse adjustment multiple Am in sequence, 1 ', Second level coarse adjustment multiple Am 2 ' and the third level coarse adjustment multiple Am 3 When the intermediate peak voltage Vpeak1' obtained after the coarse adjustment is still greater than the preset value, the preset gain Ao' is directly divided by the maximum adjustable gain multiple, and the target output signal Vt' is obtained according to the preset gain Ao', the maximum adjustable gain multiple and the initial input signal Vin'.

[0139] Combination Fig.13 Several optional fine adjustment multiples of the fine adjustment multiple An′ can be realized by the second amplifier 323 , that is, the fine adjustment unit 15 ′ also includes the second amplifier 323 .

[0140] Here, the adjustment circuit of the fine adjustment multiple An' of the third level adjustment is taken as an example.

[0141] The second amplifier 323 includes a fifth input terminal 3231 , a sixth input terminal 3232 and a third output terminal 3233 .

[0142] The fifth input terminal 3231 receives the output of the second stage adjustment.

[0143] The fifth input terminal 3231 includes a fixed resistor Rc and a variable resistor Rv, one end of the variable resistor Rv is connected between the fixed resistor Rc and the fifth input terminal 3231, and the other end is connected to the third output terminal 3233, the sixth input terminal 3232 is connected to the second fixed reference voltage Vref2, and the third output terminal 3233 is connected to the gain operational amplifier unit 11, wherein several optional fine-tuning multiples are the ratios of the variable resistor Rv to the fixed resistor Rc.

[0144] Here, the resistance of the fixed resistor Rc is 2 MΩ, the resistance variation range of the variable resistor Rv is 2 MΩ to 15.75 MΩ, and the minimum variable step length of the variable resistor Rv is 0.25 MΩ.

[0145] Specific, combined Fig.14 The variable resistor Rv includes multiple resistors with different resistance values ​​and multiple switches. Through the coordination of multiple resistors and multiple switches, the output of various resistance values ​​can be realized, that is, the resistance value variation range of the variable resistor Rv can be 2MΩ~15.75MΩ, and the minimum variable step size of the variable resistor Rv is 0.25MΩ. Here, a total of 6 bits of control bits are required.

[0146] For other descriptions of this embodiment (such as the working principle of the peak detection unit 12 ′), reference may be made to the first embodiment and will not be repeated here.

[0147] The present invention also provides a gain control method, combining Fig.15 As described above with respect to the gain adjustment module 100, the control method comprises the steps of:

[0148] Obtaining an initial input signal Vin;

[0149] Obtain an initial output signal Vout according to an initial input signal Vin and a preset gain Ao;

[0150] The gain is adjusted according to the value of the initial output signal Vin to obtain the target gain At;

[0151] Obtain a target output signal Vt according to an initial input signal Vin and a target gain At;

[0152] Convert the target output signal Vt into a digital signal.

[0153] This embodiment can adjust the gain according to the value of the initial output signal Vout to achieve automatic control of the gain, so that the final target gain At can adapt to the current EEG signal, thereby keeping the amplitude of the final target output signal Vt within a certain range, thereby improving the accuracy of analog-to-digital conversion.

[0154] In this embodiment, the step of “adjusting the gain according to the value of the initial output signal Vout to obtain the target gain At” specifically includes:

[0155] Obtaining an initial peak voltage Vpeak0 of an initial output signal Vout;

[0156] Determine whether the initial peak voltage Vpeak0 meets the preset conditions;

[0157] If yes, the fine adjustment process is started to obtain the fine adjustment multiple An, and the product of the fine adjustment multiple An and the preset gain Ao is used as the target gain At;

[0158] If not, enter the coarse adjustment process, obtain the coarse adjustment multiple Am, replace the preset gain Ao with the product of the coarse adjustment multiple Am and the preset gain Ao and obtain the corresponding intermediate peak voltage Vpeak1, and enter the fine adjustment process when the intermediate peak voltage Vpeak1 meets the preset conditions.

[0159] Here, there may be multiple schemes for the fine adjustment process and the coarse adjustment process.

[0160] In the first specific embodiment, the step of "determining whether the initial peak voltage Vpeak0 meets the preset condition; if so, entering the fine adjustment process, and taking the product of the fine adjustment multiple An and the preset gain Ao as the target gain At" specifically includes:

[0161] Determine whether the initial peak voltage Vpeak0 is within a preset range;

[0162] If so, the fine-tuning process is entered to obtain the current peak voltage Vpeak and obtain the fine-tuning multiple An based on the current peak voltage Vpeak. The product of the fine-tuning multiple An and the preset gain Ao is used as the target gain At. The fine-tuning multiple An is the multiple between the current peak voltage Vpeak and the target value.

[0163] In the second specific embodiment, the step of "determining whether the initial peak voltage Vpeak' meets the preset conditions; if so, entering the fine adjustment process, and taking the product of the fine adjustment multiple An' and the preset gain Ao' as the target gain At'" specifically includes:

[0164] Determine whether the initial peak voltage Vpeak' is less than a preset value;

[0165] If so, the fine-tuning process is entered to determine whether the difference between the initial peak voltage Vpeak' and the preset value is less than the preset threshold. If it is not less than the preset threshold, the fine-tuning multiple An' is obtained, and the product of the fine-tuning multiple An' and the preset gain Ao' is used to replace the preset gain Ao' and obtain the corresponding temporary peak voltage Vpeak2' until the difference between the temporary peak voltage Vpeak2' and the preset value is less than the preset threshold. If it is less than the preset threshold, the product of the current fine-tuning multiple An' and the preset gain Ao' is used as the target gain At'.

[0166] For other descriptions of the gain control method of the present invention, reference may be made to the description of the gain adjustment module 100 , which will not be repeated here.

[0167] It should be noted that the modules and units of the present invention may be independent or combined together.

[0168] In summary, due to the large amplitude variation of EEG signals, a certain period of sampling is required to determine the peak voltage and then determine the gain adjustment factor. The present invention adopts a specific algorithm to successively approximate the current peak voltage, which not only reduces the number of comparators but also reduces the requirements for the comparator offset voltage. It can achieve higher accuracy and fast quantization, and quickly determine the target gain At of the gain amplifier unit 11.

[0169] The gain control unit 10 of this embodiment can adjust the gain according to the value of the initial output signal Vout to achieve automatic control of the gain, so that the target gain At finally obtained can adapt to the current EEG signal, thereby making the amplitude of the target output signal Vt finally output to the analog-to-digital conversion unit 20 remain within a certain range, thereby improving the accuracy of the analog-to-digital conversion.

[0170] It should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation mode may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0171] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gain adjustment module, It is characterized in that The invention comprises a gain control unit and an analog-to-digital conversion unit connected to the gain control unit, wherein the gain control unit is used to obtain an initial output signal according to a preset gain and a received initial input signal, and to adjust the gain according to the value of the initial output signal to obtain a target gain, and the gain control unit obtains a target output signal according to the target gain and the initial input signal, and the analog-to-digital conversion unit converts the target output signal into a digital signal; The gain control unit includes a gain amplifier unit, a peak detection unit, a comparison unit and a fine adjustment unit. The gain amplifier unit and the peak detection unit are used to obtain an initial output signal and an initial peak voltage respectively to complete a peak acquisition cycle. The gain amplifier unit is a low-noise gain amplifier unit. The comparison unit is used to determine whether the initial peak voltage is less than a preset value. When the initial peak voltage is less than the preset value, the fine-tuning process is entered, and the comparison unit continues to determine whether the difference between the initial peak voltage and the preset value is less than a preset threshold value. If it is not less than the preset threshold value, the gain amplifier unit obtains the fine-tuning multiple provided by the fine-tuning unit and replaces the preset gain with the product of the fine-tuning multiple and the preset gain. The gain amplifier unit and the peak detection unit obtain a temporary peak voltage according to a peak acquisition cycle, and the peak acquisition cycle is repeated until the difference between the obtained temporary peak voltage and the preset value is less than the preset threshold value. If it is less than the preset threshold value, the fine-tuning unit obtains the current fine-tuning multiple and transmits it to the gain amplifier unit, and the gain amplifier unit uses the product of the current fine-tuning multiple and the preset gain as the target gain.

2. The gain adjustment module according to claim 1, It is characterized in that The gain control unit also includes a coarse adjustment unit. When the initial peak voltage is not less than a preset value, a coarse adjustment process is entered. The gain operational amplifier unit obtains a coarse adjustment multiple provided by the coarse adjustment unit and replaces the preset gain with the product of the coarse adjustment multiple and the preset gain. The gain operational amplifier unit and the peak detection unit obtain an intermediate peak voltage according to a peak acquisition cycle. When the intermediate peak voltage meets a preset condition, a fine adjustment process is entered. The gain operational amplifier unit uses the product of the coarse adjustment multiple, the fine adjustment multiple and the preset gain as the target gain.

3. The gain adjustment module according to claim 2, It is characterized in that The coarse adjustment multiple includes several optional coarse adjustment multiples, the fine adjustment multiple includes several optional fine adjustment multiples, and the several optional coarse adjustment multiples include a first level coarse adjustment multiple, a second level coarse adjustment multiple and a third level coarse adjustment multiple that can be selected in sequence.

4. The gain adjustment module according to claim 1, It is characterized in that The fine adjustment multiple is realized by a second amplifier, which includes a fifth input terminal, a sixth input terminal and a third output terminal, the fifth input terminal includes a fixed resistor and a variable resistor, one end of the variable resistor is connected between the fixed resistor and the fifth input terminal, and the other end is connected to the third output terminal, the sixth input terminal is connected to a second fixed reference voltage, and the third output terminal is connected to the gain operational amplifier unit, wherein the fine adjustment multiple is the ratio of the variable resistor to the fixed resistor.

5. The gain adjustment module according to claim 1, It is characterized in that The preset gain is the maximum gain of the gain adjustment module.

6. The gain adjustment module according to claim 1, It is characterized in that The peak detection unit includes a first switch, a diode, a first resistor, a first capacitor connected to the ground, a second resistor connected to the ground and connected in series, and a second switch, wherein the first switch is used to control the input of the peak detection unit, the second switch is used to reset, the second resistor is used to limit the discharge current, the diode cooperates with the first resistor and the first capacitor to realize unidirectional storage of a plurality of input voltages, and then obtains the peak voltage through the plurality of input voltages and serves as the output of the peak detection unit.

7. The gain adjustment module according to claim 1, It is characterized in that The peak detection unit includes a third amplifier, which includes a seventh input terminal, an eighth input terminal and a fourth output terminal. The seventh input terminal is provided with a third resistor and a second capacitor. The eighth input terminal is connected to the fourth output terminal and includes a fourth resistor, a third switch and a third capacitor that are grounded and connected in series. The fourth output terminal is provided with a transistor, one end of the transistor is connected to a power supply voltage, and the other end of the transistor is connected to the third capacitor. The third resistor and the second capacitor are used for filtering, the third switch is used for resetting, and the transistor is used to generate a bias current. A peak voltage is obtained by gradually increasing a plurality of input voltages input through the seventh input terminal, and the fourth output terminal uses the obtained peak voltage as the output of the peak detection unit.

8. An implantable neural stimulation system, Features It comprises a gain adjustment module, a stimulation electrode and a terminal device as described in any one of claims 1 to 7, wherein the stimulation electrode is used to obtain an electroencephalogram signal as an initial input signal of the gain adjustment module, and the gain adjustment module transmits the converted digital signal to the terminal device.

9. A gain control method, It is characterized in that Includes steps: Obtaining an initial input signal; Acquire an initial output signal according to the initial input signal and a preset gain; Adjusting the gain according to the value of the initial output signal to obtain a target gain; Acquire a target output signal according to the initial input signal and the target gain; Converting the target output signal into a digital signal; The control method further comprises: Obtaining an initial peak voltage of the initial output signal; When it is determined that the initial peak voltage is less than the preset value, the fine-tuning process is entered to determine whether the difference between the initial peak voltage and the preset value is less than the preset threshold. If it is not less than the preset threshold, the fine-tuning factor is obtained, the product of the fine-tuning factor and the preset gain replaces the preset gain and the corresponding temporary peak voltage is obtained until the difference between the temporary peak voltage and the preset value is less than the preset threshold. If it is less than the preset threshold, the product of the current fine-tuning factor and the preset gain is used as the target gain.

10. The gain control method according to claim 9, It is characterized in that The control method further comprises: When it is determined that the initial peak voltage is not less than the preset value, the coarse adjustment process is entered, the coarse adjustment factor is obtained, the product of the coarse adjustment factor and the preset gain replaces the preset gain and the corresponding intermediate peak voltage is obtained, and the fine adjustment process is entered when the intermediate peak voltage meets the preset conditions.

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