Artificial neural electrical stimulation current control circuit

Abstract

The application discloses an artificial nerve electric stimulation current control circuit, a decoding module decodes an input control signal and transmits the input control signal into a digital-analog conversion module, the digital-analog conversion module outputs corresponding analog current according to an encoding signal input by the decoding module, a direct current biasing module is connected with the digital-analog conversion module, and the direct current biasing module provides a biasing current and a biasing voltage for the digital-analog conversion module, a voltage boosting output module is connected with the digital-analog conversion module, and the voltage boosting output module outputs the current generated by the digital-analog conversion circuit through a high-voltage-resistant MOS tube. According to the characteristics of nerve electric stimulation, the application ensures the accuracy of stimulation at a small current under the premise of meeting a sufficient stimulation current range, does not need many bit input control signals for control, guarantees the high speed of stimulation, adopts a low-voltage digital-analog conversion and a high-voltage output current mode, and thus the power saving purpose is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of implantable medical devices, and particularly relates to an artificial electric stimulation current control circuit. BACKGROUND

[0002] In an implantable neural electric stimulation medical device, how to output accurate current is the core of product technology. In actual use, due to the diversity of user's nerve tissue, the stimulation current control circuit faces many problems. First, due to the different sensitivities of users to stimulation current, the range of the current output by the stimulation current control circuit is required to be high, for example, the user of a cochlear implant requires the stimulation current to be in the range of 0-2 mA. At the same time, the user also has a high requirement for the accuracy of the current, for example, for the user of an artificial retina, different current values mean that the gray scale seen is not the same, and the user has a more detailed visual perception. Therefore, both large range stimulation and high precision stimulation are required, which is contradictory in circuit design. Second, the user has a relatively high requirement for the stimulation rate, for the user of a cochlear implant, the stimulation rate generally reaches 5 KHz, or even 20 KHz, therefore, under the condition that the transmission data rate is limited, the length of a frame of stimulation data is limited. The stimulation current amplitude value is the core parameter of a frame of stimulation data, and is often the data with the largest proportion in the stimulation data, therefore, the data length of the stimulation current amplitude value needs to be shortened as much as possible, which is inconsistent with the direction of achieving high precision stimulation. Third, due to the large difference in user's nerve tissue impedance, the voltage resistance required by the stimulation current control circuit is high, but this will lead to an increase in circuit power consumption, and how to reasonably control the circuit power consumption is also a difficulty in the design of the circuit. SUMMARY

[0003] Therefore, the purpose of the present application is to provide an artificial neural electric stimulation current control circuit, which provides four different current ranges, thereby achieving high precision at small current and high amplitude at large current under the premise of limited control signal data, and reducing the overall power consumption of the circuit through the mode of low-voltage digital-to-analog conversion and amplification and voltage boost output, and further improving the precision and reliability of the output current through the mode of center symmetry of large and small currents and through the mode of odd and even bit control and direct current bias provided in pairs, and the entire circuit has the advantages of convenient operation, stability and reliability, easy integration, etc.

[0004] To achieve the above purpose, the present application provides an artificial neural electric stimulation current control circuit, which at least comprises a decoding module, a digital-to-analog conversion module, a direct current bias module and a voltage boost output module, wherein,

[0005] The decoding module receives an externally transmitted input control signal, converts the input control signal into a decoding control signal, and is used to control the output current of the digital-to-analog conversion module;

[0006] The digital-to-analog conversion module is connected with the decoding module, and comprises a basic current conversion circuit, a 2-time basic current conversion circuit, a 4-time basic current conversion circuit, and an 8-time basic current conversion circuit, and the corresponding output current is generated according to the decoding control signal;

[0007] The direct current bias module is connected with the digital-to-analog conversion module, and is composed of four direct current bias circuits, and provides the direct current bias voltage for the digital-to-analog conversion module.

[0008] The voltage conversion circuit is connected with the digital-to-analog conversion module, and the current output by the digital-to-analog conversion module is amplified in proportion, and the current is output through the high-voltage-resistant MOS tube through the voltage conversion.

[0009] Preferably, the input control signal of the decoding module is a 6-12-bit digital signal.

[0010] Preferably, the decoding control signal of the decoding module is divided into high 4 bits and low several bits, and the high 4 bits are used to control the generation of different range currents.

[0011] Preferably, the digital-to-analog conversion module provides four different range currents.

[0012] Preferably, the digital-to-analog conversion module is composed of two groups of basic current conversion circuits, two groups of 2-time basic current conversion circuits, two groups of 4-time basic current conversion circuits, and two groups of 8-time basic current conversion circuits, wherein the basic current conversion module and the 8-time basic current conversion circuit share the direct current bias voltage, the 2-time basic current conversion circuit and the 4-time basic current conversion circuit share the direct current bias voltage, and the layout structure is center-symmetric.

[0013] Preferably, the two groups of basic current conversion circuits, the two groups of 2-time basic current conversion circuits, the two groups of 4-time basic current conversion circuits, and the two groups of 8-time basic current conversion circuits in the digital-to-analog conversion module are respectively controlled by the odd and even bits in the low several bits of the decoding control signal.

[0014] Preferably, the voltage conversion circuit amplifies the current output by the digital-to-analog conversion module by 1-16 times, and the maximum output voltage is 5-32 volts.

[0015] Preferably, the voltage conversion circuit outputs a current in the range of 1-10 mA, and the minimum output current accuracy is 2-20 uA.

[0016] The beneficial effects of the present application are that the circuit controls the output of four ranges of current by dividing the input control signal into high 4 bits and low several bits, when the high 4 bits change, the range is automatically switched, and finally the current converted by digital-to-analog conversion is amplified and boosted and output through a high-voltage MOS tube, the output current of the whole circuit not only meets monotonicity, but also realizes high resolution output when the current is small, and the current output amplitude meets the demand and the voltage is sufficient when the current is large, and in addition to the necessary current for stimulation, the overall circuit has low power consumption, is flexible and easy to control, can adapt to high stimulation rate stimulation and is easy to integrate. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to make the purpose, technical scheme and beneficial effects of the present application clearer, the present application provides the following drawings for illustration:

[0018] Figure 1 The figure is a whole block diagram of a specific application example of the artificial nerve electric stimulation current control circuit of the embodiment of the present application.

[0019] Figure 2 The figure is a specific block diagram of a specific application example of the artificial nerve electric stimulation current control circuit of the embodiment of the present application.

[0020] Figure 3 The figure is a minimum unit circuit diagram of a basic current conversion circuit of a specific application example of the artificial nerve electric stimulation current control circuit of the embodiment of the present application.

[0021] Figure 4 The figure is a digital-to-analog conversion module integrated circuit layout of a specific application example of the artificial nerve electric stimulation current control circuit of the embodiment of the present application.

[0022] Figure 5 The figure is a relationship diagram of the output current and the input control signal of a specific application example of the artificial nerve electric stimulation current control circuit of the embodiment of the present application. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0024] Referring to Figures 1-2 , the figure is a whole block diagram and a specific block diagram of a specific application example of the artificial nerve electric stimulation current control circuit 10 of the embodiment of the present application, wherein,

[0025] The artificial nerve electric stimulation current control circuit comprises at least a decoding module 110, a digital-to-analog conversion module 120, a direct current biasing module 130 and a boosting output module 140, wherein,

[0026] The decoding module 110 receives an external incoming input control signal, which is an 8-bit control signal, converts the input control signal into decoding control signals R, RC and C signals for controlling the output current of the digital-to-analog conversion module 120, and divides the input control signal into high 4 bits Hi<3:0> and low 4 bits Lo<3:0>, wherein Hi<3:0> and Lo<3:0> satisfy the decoding relationship of Table 1, Table 2 and Table 3 with R, RC and C respectively, and the high 4 bits are used to control the generation of 4 different ranges of currents.

[0027] The digital-to-analog conversion module 120 is connected with the decoding module 110, and includes two groups of basic current conversion circuits 121, two groups of 2 times basic current conversion circuits 122, two groups of 4 times basic current conversion circuits 123 and two groups of 8 times basic current conversion circuits 124, which generate corresponding output currents according to the decoding control signals.

[0028] The DC bias module 130 is connected with the digital-to-analog conversion module 120 and is composed of four DC bias circuits 131, which provide a DC bias voltage for the digital-to-analog conversion module 120.

[0029] The boost output module 140 is connected with the digital-to-analog conversion module 120, amplifies the output current of the digital-to-analog conversion module 120 in a proportional manner, and outputs the current through a high-voltage-resistant MOS tube through voltage conversion.

[0030] The boost output module 140 amplifies the output current of the digital-to-analog conversion module 120 by 1-16 times, and the maximum output voltage is 5-32 volts.

[0031] Figure 3 It is the minimum unit circuit diagram of the basic current conversion circuit 121 of a specific application example in the artificial neural electrical stimulation current control circuit of the embodiment of the application. Among them, M5 and M6 are controlled by the output voltage of the DC bias module 130, and provide corresponding currents. When the control signal R is 1, the right branch is selected; when the control signals RC and C are both 1, the left branch is selected.

[0032] Referring to Figure 4 , it is the integrated circuit layout of the digital-to-analog conversion module 120 of a specific application example in the artificial neural electrical stimulation current control circuit of the embodiment of the application. The digital-to-analog conversion module 120 is composed of two groups of basic current conversion circuits 121, two groups of 2 times basic current conversion circuits 122, two groups of 4 times basic current conversion circuits 123 and two groups of 8 times basic current conversion circuits 124, wherein the basic current conversion module 121 and the 8 times basic current conversion circuit 124 share a DC bias voltage, the 2 times basic current conversion circuit 122 and the 4 times basic current conversion circuit 123 share a DC bias voltage, and are centrally symmetrical in the layout structure.

[0033] The two groups of basic current conversion circuits 121, 2 times basic current conversion circuit 122, 4 times basic current conversion circuit 123 and 8 times basic current conversion circuit 124 in the digital-to-analog conversion module are controlled by the low 4-bit odd and even bits in the decoding control signal, so as to realize the sequential switching selection.

[0034] Figure 5 The output current and input control signal relationship diagram of a specific application example of the artificial nerve electric stimulation current control circuit of the embodiment of the application is shown. When the high four bits Hi<3:0> of the input control signal are 0000-0011, the minimum unit in the basic current conversion circuit 121 is sequentially selected by the R, RC and C control signals, the output current is 0-128uA, and the minimum current step is 2uA; when the high four bits Hi<3:0> of the input control signal are 0100-0111, the minimum unit in the 2 times basic current conversion circuit 122 is sequentially selected by the R, RC and C control signals while the basic current conversion circuit 121 is always selected, the output current is 132uA-384uA, and the minimum current step is 4uA; when the high four bits Hi<3:0> of the input control signal are 1000-1011, the minimum unit in the 4 times basic current conversion circuit 123 is sequentially selected by the R, RC and C control signals while the basic current conversion circuit 121 and the 2 times basic current conversion circuit 122 are always selected, the output current is 388uA-896uA, and the minimum current step is 8uA; when the high four bits Hi<3:0> of the input control signal are 1100-1111, the minimum unit in the 8 times basic current conversion circuit 124 is sequentially selected by the R, RC and C control signals while the basic current conversion circuit 121, the 2 times basic current conversion circuit 122 and the 4 times basic current conversion circuit 123 are always selected, the output current is 896uA-1904uA, and the minimum current step is 16uA. The actual test results show that the DNL of the digital-to-analog conversion module 120 is 0.18LSB, and the error between the maximum actual output current and the theoretical value is less than 2.2%.

[0035] Table 1 Input control signal high four bits (Hi<3:0>) and output control signal R decoding table

[0036]

[0037]

[0038] Table 2 Input control signal high four bits (Hi<3:0>) and output control signal RC decoding table

[0039] Hi<3:0> RC<0> RC<1> RC<2> RC<3> RC<4> RC<5> RC<6> … RC<14> RC<15> 0000 1 0 0 0 0 0 0 0 0 0001 0 1 0 0 0 0 0 0 0 0010 0 0 1 0 0 0 0 0 0 0011 0 0 0 1 0 0 0 0 0 0100 0 0 0 0 1 0 0 0 0 0101 0 0 0 0 0 1 0 0 0 0110 0 0 0 0 0 0 1 0 0 …… 1110 0 0 0 0 0 0 0 1 0 1111 0 0 0 0 0 0 0 0 1

[0040] Table 3 Input control signal low four bits (Lo<3:0>) and output control signal C decoding table

[0041] Lo<3:0> C<0> C<1> C<2> C<3> C<4> C<5> C<6> … C<14> C<15> 0000 0 0 0 0 0 0 0 0 0 0001 0 1 0 0 0 0 0 0 0 0010 0 1 1 0 0 0 0 0 0 0011 0 1 1 1 0 0 0 0 0 0100 0 1 1 1 1 0 0 0 0 0101 0 1 1 1 1 1 0 0 0 0110 0 1 1 1 1 1 1 0 0 …… 1110 0 1 1 1 1 1 1 1 0 1111 0 1 1 1 1 1 1 1 1

[0042] The circuit of the present application can meet the needs of different users according to different characteristics of nerve electric stimulation, maintain the current output accuracy at small current, and ensure the current output range to meet the user's needs by increasing the range at large current, which is suitable for high-speed stimulation circuit, reduces the power consumption of the circuit through high and low voltage circuit distribution, and the whole circuit has the characteristics of accurate stimulation, easy integration, flexibility and reliability.

[0043] Finally, it should be pointed out that the above preferred embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present application.

Claims

1. An artificial neural electrical stimulation current control circuit, comprising: At least comprising: decoding module, digital-to-analog conversion module, DC bias module and boost output module, wherein, The decoding module receives external incoming input control signal, converts the input control signal into decoding control signal, which is used to control the output current of the digital-to-analog conversion module; The digital-to-analog conversion module is connected with the decoding module, including basic current conversion circuit, 2 times basic current conversion circuit, 4 times basic current conversion circuit, 8 times basic current conversion circuit, and corresponding output current is generated according to the decoding control signal; The DC bias module is connected with the digital-to-analog conversion module, which is composed of four DC bias circuits, and provides DC bias voltage for the digital-to-analog conversion module; The boost output module is connected with the digital-to-analog conversion module, which amplifies the output current of the digital-to-analog conversion module in proportion, and outputs the current through the high-voltage resistant MOS tube through voltage conversion; The decoding control signal of the decoding module is divided into high 4 bits and low several bits, wherein the high 4 bits are used to control the generation of different range currents; The boost output module amplifies the output current of the digital-to-analog conversion module by 1~16 times, and the maximum output voltage is 5~32 volts; The two groups of basic current conversion circuits, two groups of 2 times basic current conversion circuits, two groups of 4 times basic current conversion circuits and two groups of 8 times basic current conversion circuits in the digital-to-analog conversion module are respectively controlled by the odd and even bits of the low several bits in the decoding control signal.

2. The artificial neural electrical stimulation current control circuit of claim 1, wherein, The input control signal of the decoding module is 6~12 bit digital signal.

3. The artificial neural electrical stimulation current control circuit of claim 1, wherein, The digital-to-analog conversion module provides four different range currents.

4. The artificial neural electric stimulation current control circuit of claim 1, wherein, The digital-to-analog conversion module is composed of two groups of basic current conversion circuits, two groups of 2 times basic current conversion circuits, two groups of 4 times basic current conversion circuits and two groups of 8 times basic current conversion circuits, wherein the basic current conversion module and the 8 times basic current conversion circuit share the DC bias voltage, the 2 times basic current conversion circuit and the 4 times basic current conversion circuit share the DC bias voltage, and the layout structure is center symmetric.

5. The artificial neural electrical stimulation current control circuit of claim 1, wherein, The output current range of the boost output module is 1~10 mA, and the minimum output current accuracy is 2~20 uA.

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