Adaptive eeg signal closed-loop control stimulator, chip and system

Abstract

The application provides a self-adaptive electroencephalogram closed-loop regulation stimulator, a chip and a system, and relates to the technical field of medical devices.The stimulator comprises at least two electrodes and a data analysis and control module, wherein: for each electrode, the electrode port of the electrode is connected with an acquisition module and a stimulation module, and the acquisition module is connected with the data analysis and control module; the acquisition module comprises an amplifier circuit and a voltage range detection unit, the electrode port is connected with the amplifier circuit and the voltage range detection unit, the voltage range detection unit is connected with the amplifier circuit, the voltage range detection unit is used for generating a gain control signal based on different ranges of electroencephalogram signals, and the amplifier circuit is used for determining the amplification multiple of the acquired electroencephalogram signals based on the gain control signal; and the stimulation module is connected with the data analysis and control module.The application can realize dynamic range adjustment of different electroencephalogram signals, and meanwhile, the overall size and power consumption of the stimulator are reduced.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an adaptive EEG signal closed-loop modulation stimulator, chip, and system. Background Technology

[0002] For neurological disorders such as Parkinson's disease and epilepsy, closed-loop deep brain stimulators overcome the problems of untimely adjustment of stimulation parameters and low stimulation efficiency in open-loop deep brain stimulators. By analyzing and processing the acquired electroencephalogram (EEG) signals and then dynamically adjusting the stimulation parameters, the therapeutic effect on patients can be improved. The amplitude of EEG signals is typically tens of microvolts to several millivolts, while the amplitude of electrical stimulation artifacts can reach several milli-hundreds of volts. Therefore, the range of EEG signals that the acquisition circuit needs to process needs to be increased from 45dB to 75dB. In other words, the closed-loop EEG signal control system requires the acquisition circuit to be able to respond to high dynamic range EEG signals in a very short time.

[0003] In existing technologies, low-gain analog front-end amplifiers and high-resolution analog-to-digital converters are generally used to quickly acquire EEG signals with a high dynamic range. However, the signal range of the EEG signal acquisition circuit only increases after electrical stimulation, and in most cases it remains within a relatively small signal range. If a high-resolution analog-to-digital converter is used, the EEG signal range is fixed, resulting in a large overall size and power consumption of the closed-loop modulation stimulator. Therefore, simultaneously satisfying the requirements for adjusting the dynamic range of the acquisition circuit and reducing the power consumption of the closed-loop modulation stimulator is a problem that urgently needs to be solved. Summary of the Invention

[0004] This invention provides an adaptive EEG signal closed-loop modulation stimulator, chip, and system to address the shortcomings of existing technologies that cannot simultaneously meet the requirements of signal range and low power consumption at different times, thereby achieving dynamic range adjustment of different EEG signals while reducing the overall size and power consumption of the stimulator.

[0005] This invention provides an adaptive closed-loop modulation stimulator for electroencephalogram (EEG) signals, comprising: at least two electrodes and a data analysis and control module, wherein:

[0006] The electrodes are used to receive EEG signals or output stimulation current. For each electrode, the electrode port is connected to a data acquisition module and a stimulation module. The data acquisition module is connected to the data analysis and control module. The data acquisition module is used to acquire EEG signals of different ranges and input them into the data analysis and control module.

[0007] The acquisition module includes an amplifier circuit and a voltage range detection unit. The electrode port is connected to the amplifier circuit and the voltage range detection unit. The voltage range detection unit is connected to the amplifier circuit. The voltage range detection unit is used to generate a gain control signal based on EEG signals of different ranges. The amplifier circuit is used to determine the amplification factor of the acquired EEG signal based on the gain control signal.

[0008] The stimulation module is connected to the data analysis and control module. The data analysis and control module is used to generate stimulation parameter control signals based on the electroencephalogram (EEG) signals. The stimulation module is used to generate stimulation current based on the stimulation parameter control signals and output it to each of the electrodes.

[0009] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the voltage range detection unit includes: a peak-to-peak detection circuit and a threshold voltage comparator, wherein:

[0010] The peak-to-peak detection circuit is connected to the electrode port and the threshold voltage comparator. The peak-to-peak detection circuit is used to determine the peak voltage corresponding to the EEG signal received by the electrode port. The threshold voltage comparator is used to determine the gain control signal based on the comparison result of the peak voltage and the preset voltage, and output it to the amplifier circuit.

[0011] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the gain control signal includes: binary number 0 or binary number 1;

[0012] When the gain control signal includes a binary number 0, the amplifier circuit determines the amplification factor of the EEG signal based on the binary number 0 to be greater than 1;

[0013] When the gain control signal includes the binary number 1, the amplification factor of the EEG signal determined by the amplifier circuit based on the binary number 1 is less than 1.

[0014] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the amplifier circuit includes: a fixed-gain amplifier, a low-pass filter, and a variable-gain amplifier, wherein:

[0015] The input of the fixed-gain amplifier is connected to the electrode port, and the output of the fixed-gain amplifier is connected to the input of the low-pass filter. The fixed-gain amplifier is used to amplify the acquired EEG signal based on a fixed amplification factor. The low-pass filter is used to filter the amplified EEG signal. The input of the variable-gain amplifier is connected to the output of the low-pass filter and the output of the threshold voltage comparator. The output of the variable-gain amplifier is connected to an N-to-1 analog selector. The variable-gain amplifier is used to amplify the filtered EEG signal based on the gain control signal generated by the voltage range detection unit. The N-to-1 analog selector is used to output the EEG signal corresponding to any one of the electrodes.

[0016] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the low-pass filter includes: a transconductance gm capacitance C low-pass filter or a current split transconductance gm low-pass filter.

[0017] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the stimulation module includes: a local logic control circuit, a digital-to-analog converter, a current driver, and an electrode selection switch array, wherein:

[0018] The local logic control circuit is connected to the data analysis and control module, the digital-to-analog converter, the current driver, and the electrode selection switch array. The digital-to-analog converter is connected to the current driver, and the current driver is connected to the electrode selection switch array, wherein:

[0019] The local logic control circuit is used to receive the stimulation parameter control signal generated by the data analysis and control module, and determine the current polarity control signal, the current magnitude control signal, and the electrode selection control signal. The digital-to-analog converter is used to adjust the magnitude of the stimulation current output to the current driver based on the current magnitude control signal. The current driver is used to change the polarity of the stimulation current based on the current polarity control signal. The electrode selection switch array is used to output stimulation current to each of the determined electrodes based on the electrode selection control signal.

[0020] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the digital-to-analog converter includes a current-mode digital-to-analog converter, wherein:

[0021] When the matching accuracy is less than or equal to a preset threshold, the current-mode digital-to-analog converter includes a binary weighted current array;

[0022] When the matching accuracy is greater than a preset threshold, the current-type digital-to-analog converter includes a combination structure of a thermometer code-type current array and a binary weighted current array.

[0023] According to the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, the acquisition module further includes: an analog-to-digital conversion unit, the analog-to-digital conversion unit being connected to an N-to-1 analog selector and the data analysis and control module, the analog-to-digital conversion unit being used to convert the analog EEG signal output by the N-to-1 analog selector into a digital EEG signal.

[0024] The present invention also provides an adaptive EEG signal closed-loop modulation stimulation chip, including the adaptive EEG signal closed-loop modulation stimulator as described in any of the above claims.

[0025] The present invention also provides an adaptive EEG signal closed-loop modulation stimulation system, comprising the adaptive EEG signal closed-loop modulation stimulation chip as described in any of the above claims.

[0026] The adaptive EEG signal closed-loop modulation stimulator, chip, and system provided by this invention acquire EEG signals through various electrodes. After electrical stimulation, the voltage range detection unit in the acquisition module generates gain control signals based on different ranges of EEG signals. This allows the amplifier circuit to determine the amplification factor of the acquired EEG signals based on the gain control signals. After the amplified EEG signals are efficiently analyzed and processed by the data analysis and control module, the stimulation parameter control signals are dynamically adjusted. This allows the stimulation module to generate a stimulation current based on the stimulation parameter control signals and perform electrical stimulation through the electrodes. This achieves rapid acquisition and dynamic range adjustment of different EEG signals, while reducing the overall size and power consumption of the stimulator. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a connection diagram of the adaptive EEG signal closed-loop modulation stimulator provided by the present invention;

[0029] Figure 2 This is a connection diagram of the voltage range detection unit provided by the present invention;

[0030] Figure 3 This is a circuit diagram of the threshold voltage comparator provided by the present invention;

[0031] Figure 4 This is a circuit diagram of the amplifier circuit provided by the present invention;

[0032] Figure 5 This is a schematic diagram of the resistor array for the variable resistor R2 provided by the present invention;

[0033] Figure 6 This is a circuit diagram of the current split transconductance gm low-pass filter provided by the present invention;

[0034] Figure 7 This is a circuit diagram of the stimulation module provided by the present invention;

[0035] Figure 8 This is an example connection diagram of the 64-channel adaptive EEG signal closed-loop modulation stimulator provided by the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] To quickly respond to high dynamic range EEG signals, low-gain analog front-end amplifiers and high-resolution analog-to-digital converters (ADCs) are generally used. The low gain of the analog front-end amplifier avoids the saturation problem caused by electrical stimulation artifacts, while the high-resolution ADC digitizes the high dynamic range EEG signals for digital signal processing. For low-frequency EEG signals, low-sampling-rate ADCs typically employ successive approximation ADCs and Sigma-delta ADCs, with a relatively fixed signal range. Successive approximation ADCs have smaller area and power consumption, but their high resolution results in lower accuracy. Sigma-delta ADCs offer higher accuracy, but oversampling leads to excessive power consumption. Furthermore, the signal range in the EEG signal acquisition circuit only increases after electrical stimulation; in most cases, the signal range is relatively small. If a high dynamic range ADC is used, a resolution of 16 bits or higher is required, leading to an increased data rate. Moreover, as the number of acquisition channels increases, the overall size and power consumption of the closed-loop modulated stimulator also increase exponentially.

[0038] To address the limitations of existing closed-loop modulated stimulators in simultaneously satisfying the dynamic range requirements of the acquisition circuit, and considering the overall size and power consumption issues of the closed-loop modulated stimulator, this invention provides an adaptive EEG signal closed-loop modulated stimulator. Figure 1 This is a connection diagram of the adaptive EEG signal closed-loop modulation stimulator provided by the present invention, as shown below. Figure 1 As shown, the adaptive EEG signal closed-loop modulation stimulator includes: at least two electrodes and a data analysis and control module, wherein:

[0039] The electrodes are used to receive EEG signals or output stimulation current. For each electrode, the electrode port is connected to a data acquisition module and a stimulation module. The data acquisition module is connected to the data analysis and control module. The data acquisition module is used to acquire EEG signals of different ranges and input them into the data analysis and control module.

[0040] The acquisition module includes an amplifier circuit and a voltage range detection unit. The electrode port is connected to the amplifier circuit and the voltage range detection unit. The voltage range detection unit is connected to the amplifier circuit. The voltage range detection unit is used to generate a gain control signal based on EEG signals of different ranges. The amplifier circuit is used to determine the amplification factor of the acquired EEG signal based on the gain control signal.

[0041] The stimulation module is connected to the data analysis and control module. The data analysis and control module is used to generate stimulation parameter control signals based on the electroencephalogram (EEG) signals. The stimulation module is used to generate stimulation current based on the stimulation parameter control signals and output it to each of the electrodes.

[0042] Specifically, in existing closed-loop modulated stimulators, the acquisition circuit cannot simultaneously meet the dynamic range requirements of the acquisition circuit, and considering the overall size and power consumption of the closed-loop modulated stimulator, the present invention addresses this issue. In this embodiment, after the EEG signals are acquired by each electrode, the voltage range detection unit in the acquisition module determines the gain control signal based on the range of different EEG signals. This allows the amplifier circuit to adjust the amplification factor of the EEG signals according to the gain control signal, ensuring that the amplitude of the subsequently amplified EEG signals meets the dynamic range of voltage conversion. Simultaneously, the amplifier circuit further reduces the overall size and power consumption of the adaptive EEG signal closed-loop modulated stimulator. After the amplifier circuit filters and amplifies the EEG signals, they are transmitted to the data analysis and control module for processing and analysis, generating a stimulation parameter control signal. This allows the stimulation module to dynamically adjust the stimulation current based on the stimulation parameter control signal, further improving the efficiency of electrical stimulation after the stimulation current passes through the selected electrodes, thereby enhancing the therapeutic effect on the patient.

[0043] In addition, the voltage range detection unit only activates when electrically stimulated, and remains off at other times, further reducing the power consumption of the acquisition module.

[0044] Optionally, Figure 2 This is a connection diagram of the voltage range detection unit provided by the present invention, as shown below. Figure 2 As shown, the voltage range detection unit includes: a peak-to-peak detection circuit and a threshold voltage comparator, wherein:

[0045] The peak-to-peak detection circuit is connected to the electrode port and the threshold voltage comparator. The peak-to-peak detection circuit is used to determine the peak voltage corresponding to the EEG signal received by the electrode port. The threshold voltage comparator is used to determine the gain control signal based on the comparison result of the peak voltage and the preset voltage, and output it to the amplifier circuit.

[0046] Specifically, when electrical stimulation is received, the voltage range detection unit is activated. The peak voltage corresponding to different EEG signals is extracted through the peak-to-peak detection circuit, so that the threshold voltage comparator compares the peak voltage with the preset voltage and determines the gain control signal based on the comparison result. This allows the amplifier circuit to dynamically adjust the amplification factor of different EEG signals based on the gain control signal. In other words, the dynamic range of the acquisition module is automatically adjusted based on different EEG signals.

[0047] Optionally, Figure 3 This is a circuit diagram of the threshold voltage comparator provided by the present invention, as shown below. Figure 3 As shown, the threshold voltage comparator includes: MOSFETs M1, M2, M3, M4, M5, and M6, NOT gates D1 and D2, and a current source I1, wherein:

[0048] The output of the peak-to-peak detection circuit is connected to the gate of MOSFET M2 to input the peak voltage Vpeak. The sources of MOSFET M2 and MOSFET M1 are both connected to current source I1. The drain of MOSFET M2 is connected to the input of NOT gate D2, the drain of MOSFET M5, the drain and gate of MOSFET M4, and the gate of MOSFET M6. The output of NOT gate D2 is connected to the input of the variable gain amplifier circuit. The gate of MOSFET M1 is connected to the preset voltage terminal. The drain of MOSFET M1 is connected to the input of NOT gate D1, the drain of MOSFET M6, the drain and gate of MOSFET M3, and the gate of MOSFET M5. The sources of MOSFET M3, MOSFET M6, MOSFET M5, and MOSFET M4 are all grounded.

[0049] Optionally, the gain control signal includes: binary number 0 or binary number 1;

[0050] When the gain control signal includes a binary number 0, the amplifier circuit determines the amplification factor of the EEG signal based on the binary number 0 to be greater than 1;

[0051] When the gain control signal includes the binary number 1, the amplification factor of the EEG signal determined by the amplifier circuit based on the binary number 1 is less than 1.

[0052] Specifically, the peak voltage V in the EEG signal received at the electrode port is extracted by the peak-to-peak detection circuit.peak Then, the peak voltage V is compared with the threshold voltage comparator. peak After comparing with the preset voltage VREF, the output gain control signal D is generated. out The gain control signal D out It is a binary number, that is, the gain control signal D out It is 0 or 1, if the peak voltage V peak When the voltage is lower than the preset voltage VREF, the gain control signal D out A value of 0 indicates that the voltage generated by the stimulation current is relatively low, and the amplification factor can be set to a value greater than 1 using a variable gain amplifier circuit. If the peak voltage V... peak When the voltage is higher than the preset voltage VREF, the gain control signal D out A value of 1 indicates that the voltage generated by the stimulation current is relatively high at this time, and the amplification factor can be set to a value less than 1 by using a variable gain amplifier circuit.

[0053] It should be noted that MOSFETs M1 and M2 are PMOS transistors, while MOSFETs M3, M4, M5, and M6 are NMOS transistors. The output of the NOT gate D1 can also be used as the output of a threshold voltage comparator.

[0054] Optionally, such as Figure 1 As shown, the amplifier circuit includes: a fixed-gain amplifier, a low-pass filter, and a variable-gain amplifier, wherein:

[0055] The input of the fixed-gain amplifier is connected to the electrode port, and the output of the fixed-gain amplifier is connected to the input of the low-pass filter. The fixed-gain amplifier is used to amplify the acquired EEG signal based on a fixed amplification factor. The low-pass filter is used to filter the amplified EEG signal. The input of the variable-gain amplifier is connected to the output of the low-pass filter and the output of the threshold voltage comparator. The output of the variable-gain amplifier is connected to an N-to-1 analog selector. The variable-gain amplifier is used to amplify the filtered EEG signal based on the gain control signal generated by the voltage range detection unit. The N-to-1 analog selector is used to output the EEG signal corresponding to any one of the electrodes.

[0056] Specifically, in order to reduce circuit area and power consumption, a three-stage amplifier structure is adopted in the amplifier circuit, with a fixed-gain amplifier, a low-pass filter, and a variable-gain amplifier connected in sequence. The fixed-gain amplifier amplifies the acquired EEG signal at a fixed amplification factor, the low-pass filter filters the amplified EEG signal to achieve a lower cutoff frequency, and the variable-gain amplifier can amplify the filtered EEG signal again at a variable amplification factor based on the gain control signal generated by the voltage range detection unit, so that the swing of the input voltage of the subsequent analog-to-digital conversion unit can meet the dynamic range of voltage conversion.

[0057] Optionally, Figure 4 This is a circuit diagram of the amplifier circuit provided by the present invention, as shown below. Figure 4 As shown, in the amplifier circuit, the fixed gain amplifier can be a capacitively coupled fixed gain amplifier, the low-pass filter can be a transconductance gm capacitor C low-pass filter, and the variable gain amplifier can be a resistive feedback variable gain amplifier, wherein:

[0058] The capacitively coupled fixed-gain amplifier includes: operational amplifier Q1, two capacitors Cin, two feedback resistors Rf, and two capacitors Cf. The two capacitors Cin are connected to the non-inverting and inverting inputs of operational amplifier Q1, respectively. One capacitor Cin receives the EEG signal from the connected electrode, and the other receives the EEG reference signal. Through the coupling of the EEG signal and the EEG reference signal, the two capacitors Cin suppress the hundreds of millivolts of DC offset voltage generated by the corresponding electrode. The two feedback resistors Rf are each connected in parallel with one capacitor Cf, forming two parallel groups. One end of one parallel group is connected to the non-inverting input of operational amplifier Q1, and the other end is connected to the output of operational amplifier Q1. The other parallel group has one end connected to the inverting input of operational amplifier Q1, and the other end, Vcm, is connected to the non-inverting input of operational amplifier Q2 in the resistive feedback variable-gain amplifier. The voltage at Vcm is half of the power supply voltage. In this context, the mid-band gain Am of the capacitively coupled fixed-gain amplifier is determined by the ratio of Cin / Cf capacitors, and the low-frequency cutoff frequency fL of the high-pass filter is determined by the feedback resistor Rf and the capacitor Cf, i.e., fL = 1 / 2πRfCf.

[0059] Furthermore, the aforementioned feedback resistor Rf is determined by the equivalent resistance of two series-connected PMOS transistors Mf operating in the cutoff region, providing the DC bias voltage for operational amplifier Q1. Specifically, for one feedback resistor Rf, the sources of the two PMOS transistors Mf are connected, the gate of one PMOS transistor Mf is connected to its drain, one end of capacitor Cf, and the non-inverting input of operational amplifier Q1, and the gate of the other PMOS transistor Mf is connected to its drain, the other end of capacitor Cf, and the output of operational amplifier Q1. For the other feedback resistor Rf, the sources of the two PMOS transistors Mf are connected, the gate of one PMOS transistor Mf is connected to its drain, one end of capacitor Cf, and the inverting input of operational amplifier Q1, and the gate of the other PMOS transistor Mf is connected to its drain, the other end of capacitor Cf, and the Vcm terminal.

[0060] The transconductance gm capacitor C low-pass filter includes: operational amplifier Q gm And load capacitor C1, operational amplifier Q gm The non-inverting input terminal serves as the input terminal of the transconductance gm capacitor C low-pass filter, and is connected to the output terminal of operational amplifier Q1 in the capacitively coupled fixed-gain amplifier. gm The inverting input terminal is connected to the operational amplifier Q. gm The output terminal of the operational amplifier Q is connected to one end of the load capacitor C1, and the other end of the load capacitor C1 is grounded. gm The output terminal serves as the output terminal of a low-pass filter with transconductance gm and capacitance C. The high-frequency cutoff frequency fH is gm / 2πC. A lower cutoff frequency can be achieved by reducing the amplifier bias current to decrease the transconductance gm of the input pair transistors or by increasing the load capacitance C1.

[0061] The resistive feedback variable gain amplifier includes: operational amplifier Q2, variable resistor R1, and resistor R2. The non-inverting input of operational amplifier Q2 is connected to the Vcm terminal of a capacitively coupled fixed gain amplifier. The inverting input of operational amplifier Q2 serves as the input of the resistive feedback variable gain amplifier and is connected to operational amplifier Q2 via resistor R1. gm The output terminal, i.e., the inverting input terminal of operational amplifier Q2, is connected to one end of resistor R1 and one end of variable resistor R2, and the other end of resistor R1 is connected to operational amplifier Q2. gm The output terminal of the variable resistor R2 is connected to the output terminal of operational amplifier Q2, and the output terminal of operational amplifier Q2 serves as the output terminal of the resistive feedback variable gain amplifier. The amplification factor of the circuit is -R2 / R1. The amplification factor of this resistive feedback variable gain amplifier is adjusted by changing the value of the variable resistor R2.

[0062] Optionally, Figure 5 This is a schematic diagram of the resistor array for the variable resistor R2 provided by the present invention, as shown below. Figure 5 As shown, the switch array of the variable resistor R2 is divided into two parts: one with a gain greater than 1 and the other with a gain less than 1, selected by switches KH and KL. The conduction of KH and KL is controlled by the output Dout of the voltage detection circuit; that is, when Dout = 0, switch KH is turned on, and the gain of the variable gain amplifier is greater than 1; when Dout = 1, switch KL is turned on, and the gain of the variable gain amplifier is less than 1. Where:

[0063] 1) Resistors RH1-RHm and switches KH1-KHm form a resistor array with a gain greater than 1. The resistance values ​​of resistors RH1-RHm are all greater than that of resistor R1. The specific resistance value is selected by turning on switches KH1-KHm. Correspondingly, the gain at this time is -RHi / R1 (i=1,2,…,m).

[0064] 2) Resistors RL1-RLm and switches KL1-KLm form a resistor array with a gain less than 1. The resistance values ​​of resistors RL1-RLm are all less than that of resistor R1. The specific resistance value is selected by turning on switches KL1-KLn. Correspondingly, the gain at this time is -RLi / R1 (i=1,2,…,n).

[0065] Optionally, the low-pass filter includes: a transconductance gm capacitor C low-pass filter or a current split transconductance gm low-pass filter.

[0066] Optionally, when the frequency of the implanted EEG signal is below 10kHz, a low-pass filter with transconductance gm and capacitance C can be used. When the frequency of the non-implantable EEG signal is below 100Hz, increasing the load capacitance C1 will increase the circuit area, while decreasing the transconductance gm will affect the linearity of the low-pass filter. Therefore, a low-pass filter with split transconductance gm can be used. Based on the symmetrical amplifier structure, two NMOS transistors M15 and M16 connected in series as negative feedback are added to improve the linearity of the circuit.

[0067] Optionally, Figure 6 This is a circuit diagram of the current-split transconductance gm low-pass filter provided by the present invention, as shown below. Figure 6 As shown, the current-split transconductance gm low-pass filter includes: MOSFETs M7-16 and a current source Iss, wherein:

[0068] The gate of MOSFET M13 is connected to the drain of MOSFET M13, the gate of MOSFET M14, and the drain of MOSFET M10. The source of MOSFET M13 is connected to the source of MOSFET M14 and one end of the current source Iss. The drain of MOSFET M14 is connected to the drain of MOSFET M12 and serves as the output of the current split transconductance gm low-pass filter. The other end of the current source Iss is connected to the source of MOSFET M7, the source of MOSFET M8, and the drain of MOSFET M15. MOSFETs M7 and M8 serve as two input differential pairs. The gate of MOSFET M7 serves as the input of the current split transconductance gm low-pass filter. The drain of MOSFET M15... The gate of MOSFET M15, the drain of MOSFET M9, the gate of MOSFET M9, and the gate of MOSFET M10 are connected to the VIP terminal. The drain of MOSFET M8 is connected to the gate of MOSFET M16, the drain of MOSFET M11, the gate of MOSFET M11, and the gate of MOSFET M12. MOSFET M15 is connected to the drain of MOSFET M16 through its source to achieve a series connection between MOSFET M15 and MOSFET M16 to form negative feedback. The sources of MOSFET M9, MOSFET M10, MOSFET M16, MOSFET M11, and MOSFET M12 are all grounded.

[0069] Furthermore, when the input signal of the current-split transconductance GM low-pass filter increases, the voltages at points A and B of the first-stage differential output also rise. This increases the current flowing through MOSFETs M15 and M16, while the current source Iss outputs a fixed current, reducing the bias current flowing through the two input differential pairs MOSFETs M7 and M8. This, in turn, lowers the voltages at points A and B, preventing the output signal of the current-split transconductance GM low-pass filter from becoming distorted due to the increased input signal, thus increasing the linearity of the filter. Simultaneously, the series connection of MOSFETs M15 and M16 further reduces the current to the two input differential pairs MOSFETs M7 and M8, requiring a smaller capacitor at the same cutoff frequency, thereby reducing the circuit area. In summary, the current-split transconductance GM low-pass filter can achieve a lower cutoff frequency with lower bias current and smaller load capacitance, resulting in smaller power consumption and area. It is particularly suitable as a filtering circuit for EEG signals below 100Hz.

[0070] It should be noted that MOSFETs M7, M8, M13, and M14 are all PMOS transistors, while MOSFETs M9-M12, M15, and M16 are all NMOS transistors.

[0071] Optionally, Figure 7This is a circuit diagram of the stimulation module provided by the present invention, as shown below. Figure 7 As shown, the stimulation module includes: a local logic control circuit, a digital-to-analog converter, a current driver, and an electrode selection switch array, wherein:

[0072] The local logic control circuit is connected to the data analysis and control module, the digital-to-analog converter, the current driver, and the electrode selection switch array. The digital-to-analog converter is connected to the current driver, and the current driver is connected to the electrode selection switch array, wherein:

[0073] The local logic control circuit is used to receive the stimulation parameter control signal generated by the data analysis and control module, and determine the current polarity control signal, the current magnitude control signal, and the electrode selection control signal. The digital-to-analog converter is used to adjust the magnitude of the stimulation current output to the current driver based on the current magnitude control signal. The current driver is used to change the polarity of the stimulation current based on the current polarity control signal. The electrode selection switch array is used to output stimulation current to each of the determined electrodes based on the electrode selection control signal.

[0074] Specifically, the stimulation module can employ a constant current source for electrical stimulation. After the local logic control circuit receives the stimulation parameter control signal from the data analysis and control module, it adjusts the magnitude of the stimulation current in real time via a digital-to-analog converter and the polarity of the stimulation current via a current driver. Once the stimulation current is determined, an electrode selection switch array is used to output the stimulation current to each electrode, thereby adjusting the efficiency of electrical stimulation and improving the therapeutic effect on the patient. Multiple electrodes can share a single digital-to-analog converter and current driver.

[0075] Optionally, such as Figure 7 As shown, the digital-to-analog converter (DAC) can be a current-mode DAC. A current-mode DAC can employ a 5-bit binary weighted current source array to adjust the output current. A single current source control array ensures charge balance during electrical stimulation and reduces damage to electrodes and nerve tissue. The current-mode DAC may include: a reference current source, current source I_Ref, MOSFETs M17-M22, and switches K0-K4, wherein:

[0076] The output of the reference current source is connected to the current source I_Ref. One end of the current source I_Ref is connected to the low-voltage power supply VDDL, and the other end of the current source I_Ref is connected to the drain of MOSFET M17, the gate of MOSFET M17, and the gate of MOSFET M22. The source of MOSFET M17 and the source of MOSFET M22 are both connected to the VSSL terminal. This VSSL terminal and VDDL terminal form a power supply, and this VSSL terminal represents the ground terminal of the low-voltage power supply. The drain of MOSFET M18 is connected to one end of switch K0, the drain of MOSFET M19 is connected to one end of switch K1, the drain of MOSFET M20 is connected to one end of switch K2, the drain of MOSFET M21 is connected to one end of switch K3, and the drain of MOSFET M22 is connected to one end of switch K4. The other end of switch K0 and the other end of switch K4, after being connected, serve as the output terminal of the current-mode digital-to-analog converter and are connected to the input terminal of the current driver. All of the above-mentioned MOSFETs M17-M22 are NMOS transistors.

[0077] Optionally, such as Figure 7 As shown, the current driver includes: MOSFETs M23, M24, M25, MOSFET MD, MOSFET MS, switch K5, and switch K6, wherein:

[0078] The gate of MOSFET M23 is connected to the drain of MOSFET M23, the gate of MOSFET M24, and the gate of MOSFET MD, and serves as the input terminal of the current driver. The source of MOSFET M23 is connected to the source of MOSFET M24, the source of MOSFET MD, and the high-voltage power supply VDDH. The drain of MOSFET M24 is connected to the drain of MOSFET M25, the gate of MOSFET M25, and the gate of MOSFET MS. The source of MOSFET M25 is connected to the source of MOSFET MS and the VSSH terminal. The VSSH terminal and the VDDH terminal share a single power supply. The VSSH terminal represents the negative power supply terminal of the high-voltage power supply. The drain of MOSFET MD is connected to one end of switch K5, and the other end of switch K5 is connected to one end of switch K6, which serves as the output terminal of the current driver, outputting the stimulation current and connecting to the input terminal of the electrode selection switch array. The other end of switch K6 is connected to the drain of MOSFET MS. The local logic control circuit can, as needed, sequentially turn on or off switches K5 and K6 in the current driver according to a certain timing sequence, that is, sequentially turn on or off MOSFETs MS and MOSFET MD in the current driver according to a certain timing sequence. MOSFETs M23, M24, and MOSFET MD are all PMOS transistors, while MOSFETs M25 and MS are all NMOS transistors.

[0079] In addition, the current driver uses a high-voltage power supply VDDH, while the current-mode digital-to-analog converter, local logic control circuit, and electrode selection switch array all use a low-voltage power supply VDDL, which reduces the power consumption of the stimulation module.

[0080] Optionally, the digital-to-analog converter includes a current-mode digital-to-analog converter, wherein:

[0081] When the matching accuracy is less than or equal to a preset threshold, the current-mode digital-to-analog converter includes a binary weighted current array;

[0082] When the matching accuracy is greater than a preset threshold, the current-type digital-to-analog converter includes a combination structure of a thermometer code-type current array and a binary weighted current array.

[0083] Specifically, in this embodiment of the invention, the adaptive EEG signal closed-loop modulation stimulator has two bidirectional stimulation current outputs, and the matching accuracy of the stimulation currents in the two directions is the current control accuracy of the electrical stimulation. When the matching accuracy is less than or equal to a preset threshold, i.e., the requirement for current control accuracy of the electrical stimulation is low, the aforementioned current-type digital-to-analog converter can use a 5-bit binary weighted current array to configure the output current. When the matching accuracy is greater than the preset threshold, i.e., the requirement for current control accuracy of the electrical stimulation is high, an 8-bit current-type digital-to-analog converter is generally required. If an 8-bit binary control method is still used to configure the output stimulation current, the matching requirement for the binary weighted current array is very high. Therefore, in this embodiment of the invention, for more refined electrical stimulation applications, for an 8-bit current-type digital-to-analog converter, the high 5 bits that are difficult to achieve the matching accuracy requirement use a thermometer code current array, and the low 3 bits use a binary weighted current array. The thermometer code current array has a lower matching accuracy requirement and better dynamic characteristics. When combined with a binary weighted current array, the current control accuracy is improved while the circuit area is reduced.

[0084] Optionally, such as Figure 1 As shown, the acquisition module further includes an analog-to-digital conversion unit, which is connected to the N-to-1 analog selector and the data analysis and control module. The analog-to-digital conversion unit is used to convert the analog EEG signal output by the N-to-1 analog selector into a digital EEG signal.

[0085] Specifically, the collected EEG signals are analog signals. In order to improve the adjustment and stimulation efficiency of the EEG signals, after amplification and filtering, and after selecting one of the EEG signals for output through an N-to-1 analog selector, the analog EEG signals need to be converted into digital EEG signals through an analog-to-digital converter.

[0086] For example, Figure 8This is an example connection diagram of the 64-channel adaptive EEG signal closed-loop modulation stimulator provided by the present invention, as shown below. Figure 8 As shown, a total of 64 electrodes were used to acquire EEG signals. After the 64 electrodes acquired the EEG signals, they were input into four parallel 16-channel acquisition modules. That is, each 16 electrodes shared one acquisition module. Each 16-channel acquisition module included: 16 amplifier circuits, 16 voltage range detection units, a 16-to-1 analog selector, an input driver, and a successive approximation analog-to-digital converter. Each electrode was connected to an amplifier circuit and a voltage range detection unit. In the 16-channel acquisition module, after the 16 electrodes acquired the EEG signals, the voltage range detection unit determined the gain control signal. The signal was then amplified and filtered by a fixed gain amplifier, a low-pass filter, and a variable gain amplifier controlled by the gain control signal. The EEG signal was then output to the 16-to-1 analog selector, which selected the EEG signal of one channel. The selected EEG signal was then transmitted to the successive approximation analog-to-digital converter through the input driver. The successive approximation analog-to-digital converter converted the analog EEG signal into a digital EEG signal. After determining the digital EEG signal, a 4-to-1 digital selector transmits the target digital EEG signal determined by one of the acquisition modules to the data analysis and control module, generating a stimulation parameter control signal. This signal is then transmitted to a 16-channel stimulation module. The 16-channel stimulation module, using the stimulation parameter control signal and local control circuitry, controls a current-type digital-to-analog converter and a current driver to obtain an adjustable stimulation current. An electrode selection switch array then selects one electrode connected to the 16-channel stimulation module for electrical stimulation. There are four such 16-channel stimulation modules, i.e., four parallel 16-channel stimulation modules.

[0087] The adaptive EEG signal closed-loop modulation stimulator provided by this invention acquires EEG signals through various electrodes. After electrical stimulation, the voltage range detection unit in the acquisition module generates gain control signals based on different ranges of EEG signals. This allows the amplifier circuit to determine the amplification factor of the acquired EEG signals based on the gain control signals. After the amplified EEG signals are efficiently analyzed and processed by the data analysis and control module, the stimulation parameter control signals are dynamically adjusted. This allows the stimulation module to generate a stimulation current based on the stimulation parameter control signals and perform electrical stimulation through the electrodes. This achieves rapid acquisition and dynamic range adjustment of different EEG signals, while reducing the overall size and power consumption of the stimulator.

[0088] The present invention also provides an adaptive EEG signal closed-loop modulation stimulation chip, including the adaptive EEG signal closed-loop modulation stimulator as described in any of the above claims.

[0089] This invention also provides an adaptive EEG signal closed-loop modulation and stimulation system, comprising the adaptive EEG signal closed-loop modulation and stimulation chip as described in any of the preceding embodiments. This adaptive EEG signal closed-loop modulation and stimulation system can be applied to medical devices.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adaptive EEG signal closed-loop modulation stimulator, characterized in that, include: At least two electrodes and a data analysis and control module, wherein: The electrodes are used to receive EEG signals or output stimulation current. For each electrode, the electrode port is connected to a data acquisition module and a stimulation module. The data acquisition module is connected to the data analysis and control module. The data acquisition module is used to acquire EEG signals of different ranges and input them into the data analysis and control module. The acquisition module includes an amplifier circuit and a voltage range detection unit. The electrode port is connected to the amplifier circuit and the voltage range detection unit. The voltage range detection unit is connected to the amplifier circuit. The voltage range detection unit is used to generate a gain control signal based on EEG signals of different ranges. The amplifier circuit is used to determine the amplification factor of the acquired EEG signal based on the gain control signal. The voltage range detection unit includes a peak-to-peak detection circuit and a threshold voltage comparator, wherein: the peak-to-peak detection circuit is connected to the electrode port and the threshold voltage comparator, the peak-to-peak detection circuit is used to determine the peak voltage corresponding to the EEG signal received by the electrode port, and the threshold voltage comparator is used to determine a gain control signal based on the comparison result of the peak voltage and a preset voltage, and output it to the amplifier circuit; The amplifier circuit includes a fixed-gain amplifier, a low-pass filter, and a variable-gain amplifier. The input of the fixed-gain amplifier is connected to the electrode port, and its output is connected to the input of the low-pass filter. The fixed-gain amplifier amplifies the acquired EEG signal based on a fixed amplification factor. The low-pass filter filters the amplified EEG signal. The input of the variable-gain amplifier is connected to the output of the low-pass filter and the output of the threshold voltage comparator. The output of the variable-gain amplifier is connected to an N-to-1 analog selector. The variable-gain amplifier amplifies the filtered EEG signal based on the gain control signal generated by the voltage range detection unit. The N-to-1 analog selector outputs the EEG signal corresponding to any one of the electrodes. The stimulation module is connected to the data analysis and control module. The data analysis and control module is used to generate stimulation parameter control signals based on the electroencephalogram (EEG) signals. The stimulation module is used to generate stimulation current based on the stimulation parameter control signals and output it to each of the electrodes. The gain control signal includes: binary number 0 or binary number 1; When the gain control signal includes a binary number 0, the amplifier circuit determines the amplification factor of the EEG signal based on the binary number 0 to be greater than 1; When the gain control signal includes the binary number 1, the amplification factor of the EEG signal determined by the amplifier circuit based on the binary number 1 is less than 1.

2. The adaptive EEG signal closed-loop modulation stimulator according to claim 1, characterized in that, The low-pass filter includes: a transconductance gm capacitor C low-pass filter or a current split transconductance gm low-pass filter.

3. The adaptive EEG signal closed-loop modulation stimulator according to claim 1, characterized in that, The stimulation module includes: a local logic control circuit, a digital-to-analog converter, a current driver, and an electrode selection switch array, wherein: The local logic control circuit is connected to the data analysis and control module, the digital-to-analog converter, the current driver, and the electrode selection switch array. The digital-to-analog converter is connected to the current driver, and the current driver is connected to the electrode selection switch array, wherein: The local logic control circuit is used to receive the stimulation parameter control signal generated by the data analysis and control module, and determine the current polarity control signal, the current magnitude control signal, and the electrode selection control signal. The digital-to-analog converter is used to adjust the magnitude of the stimulation current output to the current driver based on the current magnitude control signal. The current driver is used to change the polarity of the stimulation current based on the current polarity control signal. The electrode selection switch array is used to output stimulation current to each of the determined electrodes based on the electrode selection control signal.

4. The adaptive EEG signal closed-loop modulation stimulator according to claim 3, characterized in that, The digital-to-analog converter includes a current-mode digital-to-analog converter, wherein: When the matching accuracy is less than or equal to a preset threshold, the current-mode digital-to-analog converter includes a binary weighted current array; When the matching accuracy is greater than a preset threshold, the current-type digital-to-analog converter includes a combination structure of a thermometer code-type current array and a binary weighted current array.

5. The adaptive EEG signal closed-loop modulation stimulator according to claim 1, characterized in that, The acquisition module further includes an analog-to-digital conversion unit, which is connected to the N-to-1 analog selector and the data analysis and control module. The analog-to-digital conversion unit is used to convert the analog EEG signals output by the N-to-1 analog selector into digital EEG signals.

6. An adaptive EEG signal closed-loop modulation stimulation chip, characterized in that, Including the adaptive EEG signal closed-loop modulation stimulator as described in any one of claims 1-5.

7. An adaptive EEG signal closed-loop modulation stimulation system, characterized in that, Includes the adaptive EEG signal closed-loop modulation stimulation chip as described in claim 6.

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