CN221058268U - Nerve probe, signal acquisition analog front-end circuit and analog chip thereof - Google Patents
Nerve probe, signal acquisition analog front-end circuit and analog chip thereof Download PDFInfo
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Abstract
The utility model provides a nerve probe and a signal acquisition analog front-end circuit and an analog chip thereof, comprising a low-noise amplifier circuit and a programmable gain amplifying-filtering circuit, wherein the low-noise amplifier circuit is connected with the programmable gain amplifying-filtering circuit, the low-noise amplifier circuit comprises an amplifier, a direct current servo loop and a feedback loop, and the direct current servo loop and the feedback loop are both connected with the amplifier in parallel; the programmable gain amplifying-filtering circuit comprises a programmable gain amplifying circuit and a filtering circuit, and the programmable gain amplifying circuit is connected with the filtering circuit; the low noise amplifier circuit is used for amplifying an input electric signal and inhibiting interference signals in the amplified electric signal through the programmable gain amplifying-filtering circuit. The utility model can amplify the electric signal and reduce noise, and has the function of adjustable gain so as to acquire different biological signals.
Description
Technical Field
The utility model relates to the technical field of nerve probes, in particular to a nerve probe, a signal acquisition analog front-end circuit and an analog chip thereof.
Background
The implantable nerve probe is one of the key points in the field of nerve engineering at present, has high scientific research experimental value and great potential in various fields such as future medical science and brain-computer interface development. In order to acquire and detect the mouse nerve signals, the biomedical signal acquisition chip is required to acquire bioelectric signals, and the bioelectric signals are amplified, noise reduced, filtered and the like, so that the indexes of the acquired signals such as amplitude, signal to noise ratio and the like meet the input signal requirements of a subsequent signal processing system. As one of a plurality of physiological parameters, biomedical signals are various and small in amplitude, and are the signals which are the most basic of organisms and can represent the body state most. By analyzing the signal characteristics collected by the biomedical signal acquisition chip, the health degree of the organism can be judged, and the purity of the signal extracted by the chip directly influences the accuracy of analysis and judgment, thereby influencing the diagnosis and treatment of diseases.
Chinese patent CN110755067a discloses a front-end analog circuit and a front-end analog chip for combined collection of electrocardio and pulse wave, which comprises a plurality of detection electrodes, photodiodes and light emitting diodes, wherein the signals input by the detection electrodes are amplified by a transconductance instrument amplifier circuit, the current signals provided by the photodiodes are converted into voltage signals by a transimpedance amplifier circuit, the voltage signals are amplified to output corresponding first detection signals, then the switching state of the switch inside the detection signals is controlled by a switch circuit, and the detection signals are processed by the same programmable gain amplifier circuit, low-pass filter circuit and output buffer circuit.
In the technical scheme, noise is easy to generate after the input signal of the detection electrode is amplified, and the analog circuit can only acquire one signal and does not have an adjusting function. Therefore, the design of the biomedical signal acquisition chip with good performance has great significance, and high signal-to-noise ratio, low power consumption and miniature integrability become urgent demands for the development of modern biomedical signal acquisition chips.
Disclosure of utility model
In view of the above, the present utility model provides a neural probe, and a signal acquisition analog front-end circuit and an analog chip thereof, which can amplify an electrical signal while reducing noise, and have a gain adjustable function so as to acquire different kinds of biological signals.
The technical scheme of the utility model is realized as follows:
In a first aspect, the present utility model provides a signal acquisition analog front-end circuit for a neural probe, characterized in that: comprising a low noise amplifier circuit and a programmable gain amplification-filter circuit, said low noise amplifier circuit and programmable gain amplification-filter circuit being connected, wherein,
The low-noise amplifier circuit comprises an amplifier, a direct current servo loop and a feedback loop, wherein the direct current servo loop and the feedback loop are both connected with the amplifier in parallel;
The programmable gain amplifying-filtering circuit comprises a programmable gain amplifying circuit and a filtering circuit, and the programmable gain amplifying circuit is connected with the filtering circuit;
The low noise amplifier circuit is used for amplifying an input electric signal and inhibiting interference signals in the amplified electric signal through the programmable gain amplifying-filtering circuit.
On the basis of the above technical solution, preferably, the filter circuit includes a first current mirror circuit, a second current mirror circuit, a third current mirror circuit, a fourth current mirror circuit, a field-effect transistor M17, a field-effect transistor M18, a field-effect transistor M19, and a field-effect transistor M20, wherein,
The first current mirror circuit and the second current mirror circuit are common-drain common-gate current mirrors, the third current mirror circuit and the fourth current mirror circuit are common-source common-gate current mirrors, the drain electrodes of the second current mirror circuit are electrically connected with the drain electrode of the third current mirror circuit, the source electrodes of the first current mirror circuit are connected with input voltage, and the source electrodes of the fourth current mirror circuit are grounded;
The grid electrode of the field effect transistor M17 and the grid electrode of the field effect transistor M18 are respectively connected with two drain electrodes of a transistor in the second current mirror circuit;
The source electrode of the field effect tube M17 and the source electrode of the field effect tube M18 are connected with input voltages;
The drain electrode of the field effect tube M17 is connected with the drain electrode of the field effect tube M19;
the drain electrode of the field effect tube M18 is connected with the drain electrode of the field effect tube M20;
The grid electrode of the field effect tube M19 is connected with the grid electrode of the field effect tube M20, and the source electrode of the field effect tube M19 and the source electrode of the field effect tube M20 are grounded.
On the basis of the above technical solution, preferably, the programmable gain amplifying circuit includes a fifth current mirror circuit, a field effect transistor M21 and a field effect transistor M22, wherein,
The source electrode of the field effect tube M21 is connected with an input voltage, the grid electrode of the field effect tube M21 is connected with the amplified electric signal, and the drain electrode of the field effect tube M21 is connected with the first current mirror circuit;
the source electrode of the field effect tube M22 is grounded, the grid electrode of the field effect tube M22 is connected with the amplified electric signal, and the drain electrode of the field effect tube M22 is grounded.
On the basis of the above technical solution, preferably, the fifth current mirror circuit includes a field effect transistor M501, a field effect transistor M502, a field effect transistor M51, and a field effect transistor M52, wherein,
The source electrode of the field effect transistor M501 is connected with the source electrode of the field effect transistor M502, and the connected node is also connected with the drain electrode of the field effect transistor M22;
The drain electrode of the field effect transistor M501 and the drain electrode of the field effect transistor M502 are respectively connected with two drain electrodes of the first current mirror circuit;
The grid electrode of the field effect tube M501 is connected with the signal positive input end, and the grid electrode of the field effect tube M502 is connected with the signal negative input end;
The source electrode of the field effect tube M51 is connected with the source electrode of the field effect tube M52 and is respectively connected with the drain electrode of the field effect tube M21, the drain electrode of the field effect tube M51 and the drain electrode of the field effect tube M52 are respectively connected with the two source electrodes of the third current mirror circuit, the grid electrode of the field effect tube M51 is connected with the signal positive input end, and the grid electrode of the field effect tube M52 is connected with the signal negative input end.
On the basis of the technical scheme, preferably, the amplifier comprises a first amplifier and a second amplifier which are connected in series, wherein
The first amplifier comprises a first power amplifier and a first operational amplifier, and the first power amplifier is connected in series with the first operational amplifier;
the second amplifier comprises a second power amplifier and a second operational amplifier, and the second power amplifier and the second operational amplifier are connected in series.
On the basis of the above technical solution, preferably, the dc servo loop includes an input end and an output end, the input end of the dc servo loop is connected in parallel with the first operational amplifier through the third power amplifier, and the output end of the dc servo loop is electrically connected with the programmable gain amplifying-filtering circuit.
On the basis of the above technical solution, preferably, the feedback loop includes an input end and an output end, the input end of the feedback loop is electrically connected with the programmable gain amplifying-filtering circuit, and the output end of the feedback loop is connected in parallel with the first operational amplifier.
On the basis of the above technical solution, preferably, the analog front-end circuit further includes an impedance improving loop, the impedance improving loop is respectively connected in parallel with the amplifier, the direct current servo loop and the feedback loop, and the impedance improving loop is a switched capacitor circuit.
In a second aspect, the present utility model provides a signal acquisition analog chip applied to a neural probe, including a detection electrode, a detection signal output end, and a signal acquisition analog front-end circuit as described in any one of the above, where the signal acquisition analog front-end circuit is connected to the detection electrode and the detection signal output end, respectively.
In a third aspect, the present utility model provides a nerve probe comprising a control motherboard and a syringe, wherein,
The control main board adopts the signal acquisition analog chip;
the injection tube is in communication connection with the control main board, and the movement of the injection tube is controlled by the control main board.
Compared with the prior art, the signal acquisition analog front-end circuit of the nerve probe has the following beneficial effects:
(1) The gain and the low-pass cut-off frequency of different bioelectric signals are realized by fusing the programmable gain amplifying circuit and the low-pass filter circuit, a larger unit gain bandwidth is realized by power consumption distribution, and meanwhile, the analog front-end circuit has a gain adjustable function so as to acquire different types of bioelectric signals;
(2) By adopting a fully differential structure in the low-pass filter circuit, common mode noise generated in the analog front-end circuit is suppressed, so that the noise of the analog front-end circuit is further reduced, and the stability of the programmable gain amplifying-filter circuit is improved by adding the Miller compensation in the circuit.
Drawings
In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of a signal acquisition analog front-end circuit of a nerve probe of the present utility model;
FIG. 2 is a circuit diagram of a programmable gain amplification-filter circuit of a signal acquisition analog front-end circuit of a nerve probe of the present utility model;
FIG. 3 is a schematic diagram of a low noise amplifier circuit of a signal acquisition analog front-end circuit of a nerve probe of the present utility model;
FIG. 4 is a first operational amplifier circuit of the signal acquisition analog front-end circuit of the nerve probe of the present utility model;
fig. 5 is a second operational amplifier circuit of the signal acquisition analog front-end circuit of the nerve probe of the present utility model.
Detailed Description
The following description of the embodiments of the present utility model will clearly and fully describe the technical aspects of the embodiments of the present utility model, and it is apparent that the described embodiments are only some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present utility model without making any inventive effort, are intended to fall within the scope of the present utility model.
As shown in fig. 1, the signal acquisition analog front-end circuit of the nerve probe comprises a low-noise amplifier circuit and a programmable gain amplifying-filtering circuit, wherein the low-noise amplifier circuit is connected with the programmable gain amplifying-filtering circuit, the low-noise amplifier circuit comprises an amplifier, a direct-current servo loop and a feedback loop, and the direct-current servo loop and the feedback loop are both connected with the amplifier in parallel; the programmable gain amplifying-filtering circuit comprises a programmable gain amplifying circuit and a filtering circuit, and the programmable gain amplifying circuit is connected with the filtering circuit; the low noise amplifier circuit is used for amplifying an input electric signal and inhibiting interference signals in the amplified electric signal through the programmable gain amplifying-filtering circuit.
It can be understood that the power consumption generated by the analog front-end circuit is reduced by adopting a carrier modulation method after the biological electric signals of the nerve probe are amplified by the low-noise amplification circuit, the gains and the low-pass cut-off frequencies of different biological electric signals are realized by using the switch capacitors, a larger unit gain bandwidth is realized by power consumption distribution, and meanwhile, the analog front-end circuit has a gain adjustable function so as to acquire different biological signals.
As shown in fig. 2, as a preferred embodiment of the present application, the filter circuit includes a first current mirror circuit, a second current mirror circuit, a third current mirror circuit, a fourth current mirror circuit, a field effect transistor M17, a field effect transistor M18, a field effect transistor M19, and a field effect transistor M20, wherein,
The first current mirror circuit and the second current mirror circuit are common-drain common-gate current mirrors, the third current mirror circuit and the fourth current mirror circuit are common-source common-gate current mirrors, the drain electrodes of the second current mirror circuit are electrically connected with the drain electrode of the third current mirror circuit, the source electrodes of the first current mirror circuit are connected with input voltage, and the source electrodes of the fourth current mirror circuit are grounded;
The grid electrode of the field effect transistor M17 and the grid electrode of the field effect transistor M18 are respectively connected with two drain electrodes of a transistor in the second current mirror circuit;
The source electrode of the field effect tube M17 and the source electrode of the field effect tube M18 are connected with input voltages;
The drain electrode of the field effect tube M17 is connected with the drain electrode of the field effect tube M19;
the drain electrode of the field effect tube M18 is connected with the drain electrode of the field effect tube M20;
The grid electrode of the field effect tube M19 is connected with the grid electrode of the field effect tube M20, and the source electrode of the field effect tube M19 and the source electrode of the field effect tube M20 are grounded.
The filter circuit is provided with a fully differential structure, common mode noise generated in the analog front-end circuit is restrained, so that the noise of the analog front-end circuit is further reduced, specifically, the field effect transistor M101 and the field effect transistor M102 form a first current mirror circuit, the field effect transistor M201 and the field effect transistor M202 form a second current mirror circuit, the field effect transistor M301 and the field effect transistor M302 form a third current mirror circuit, and the field effect transistor M401 and the field effect transistor M402 form a fourth current mirror circuit; the source electrode of the field-effect transistor M101 and the source electrode of the field-effect transistor M102 are connected with an input voltage VDD, the grid electrode of the field-effect transistor M101 and the grid electrode of the field-effect transistor M102 are connected, a first common grid voltage V B1 is formed between the grid electrode of the field-effect transistor M101 and the grid electrode of the field-effect transistor M102, the drain electrodes of the field-effect transistor M101 and the field-effect transistor M102 are respectively connected with the source electrode of the field-effect transistor M201 and the source electrode of the field-effect transistor M202, the grid electrode of the field-effect transistor M201 and the drain electrode of the field-effect transistor M202 are respectively connected with the drain electrode of the field-effect transistor M301 and the drain electrode of the field-effect transistor M302, the grid electrode of the field-effect transistor M301 and the grid electrode of the field-effect transistor M302 are respectively connected with the drain electrode of the field-effect transistor M401 and the drain electrode of the field-effect transistor M402, and the drain electrode of the field-effect transistor M401 and the first common grid voltage V B2 is formed, and the common grid voltage V CMFB1 is formed. The gate of the field-effect transistor M19 is connected to the gate of the field-effect transistor M20, and forms a second common-mode common-gate voltage V CMFB2.
As will be appreciated by those skilled in the art, a miller compensation circuit is further provided in the filter circuit, and specifically, a capacitor and a resistor are connected between the gate and the drain of the fet M17 and between the gate and the drain of the fet M18, where the capacitor and the resistor are connected in series. The filter circuit reduces noise of the collected bioelectric signals through the current mirror circuit and the field effect transistor, and performs low-pass filtering to remove high-frequency signal components, so that the quality of the bioelectric signals is improved.
As a preferred embodiment of the present application, the programmable gain amplifying circuit includes a fifth current mirror circuit, a field effect transistor M21 and a field effect transistor M22, wherein,
The source electrode of the field effect tube M21 is connected with an input voltage, the grid electrode of the field effect tube M21 is connected with the amplified electric signal, and the drain electrode of the field effect tube M21 is connected with the first current mirror circuit;
The source electrode of the field effect tube M22 is grounded, the grid electrode of the field effect tube M22 is connected with the second common grid voltage V B2, and the drain electrode of the field effect tube M22 is grounded.
Specifically, after the bioelectric signal is amplified, the interference signal and the modulation signal of the bioelectric signal are also amplified together to form the first common-gate voltage V B1 and the amplified electric-signal voltage V B. The fifth current mirror circuit comprises a field effect transistor M501, a field effect transistor M502, a field effect transistor M51 and a field effect transistor M52, wherein,
The source electrode of the field effect transistor M501 is connected with the source electrode of the field effect transistor M502, and the connected node is also connected with the drain electrode of the field effect transistor M22;
The drain electrode of the field effect transistor M501 and the drain electrode of the field effect transistor M502 are respectively connected with two drain electrodes of the first current mirror circuit;
The grid electrode of the field effect tube M501 is connected with the signal positive input end, and the grid electrode of the field effect tube M502 is connected with the signal negative input end;
The source electrode of the field effect tube M51 is connected with the source electrode of the field effect tube M52 and is respectively connected with the drain electrode of the field effect tube M21, the drain electrode of the field effect tube M51 and the drain electrode of the field effect tube M52 are respectively connected with the two source electrodes of the third current mirror circuit, the grid electrode of the field effect tube M51 is connected with the positive signal input end V in +, and the grid electrode of the field effect tube M52 is connected with the negative signal input end V in -.
As will be appreciated by those skilled in the art, the drain of fet M501 is connected to the drain of fet M101 and the drain of fet M502 is connected to the drain of fet M102.
The programmable gain amplifying circuit is used for carrying out fine amplification on signals with different amplitudes, so that the analog front-end circuit has the bandwidth adjustable capability, the collected bioelectric signals are amplified by adjusting the bandwidth, and meanwhile, interference signals outside the frequency band range are restrained.
As shown in fig. 3, as a preferred embodiment of the present application, the amplifier includes a first amplifier and a second amplifier, which are connected in series, wherein,
The first amplifier comprises a first power amplifier and a first operational amplifier, and the first power amplifier is connected in series with the first operational amplifier;
the second amplifier comprises a second power amplifier and a second operational amplifier, and the second power amplifier and the second operational amplifier are connected in series.
As shown in fig. 4, the first operational amplifier adopts a current multiplexing technology, adopts a grid electrode connecting an NMOS differential and a PMOS differential, and uniformly uses the grid electrode as an input amplifying tube, so that the current multiplexing connection structure has higher gain under the same power consumption, and the bandwidth of the collected bioelectric signals is not reduced.
Specifically, the circuit principle of the first operational amplifier is as follows:
The source electrode of the field effect tube M1 and the source electrode of the field effect tube M2 are connected with power supply voltage, the drain electrode of the field effect tube M1 and the drain electrode of the field effect tube M2 are respectively connected with the drain electrode of the field effect tube M3 and the drain electrode of the field effect tube M3, the source electrode of the field effect tube M3 is connected with the source electrode of the field effect tube M4, the connected node is also connected with the drain electrode of the field effect tube M5, the source electrode of the field effect tube M5 is grounded, the grid electrode of the field effect tube M5 is connected with the voltage of the feedback loop, the grid electrodes of the field effect tube M1 and the field effect tube M3 are connected with the positive signal input end V in +, and the grid electrodes of the field effect tube M2 and the field effect tube M4 are connected with the negative signal input end V in -. The MOS tube pseudo resistor is further connected between the drain electrode and the grid electrode of the field effect tube M1, the MOS tube pseudo resistor is connected between the drain electrode and the grid electrode of the field effect tube M2, the capacitance value of an integral capacitor required by the amplifier is greatly reduced by setting the MOS tube pseudo resistor, and the analog front-end circuit can control the gain of the circuit by adjusting the resistance value of the MOS tube pseudo resistor.
As shown in FIG. 5, the second operational amplifier adopts transconductance bootstrap to improve the input transconductance, so as to optimize the power consumption and noise of the analog front-end circuit, and the PMOS tube in the second operational amplifier is also an amplifying tube, so that the input transconductance of the low-noise amplifying circuit is improved, and the generated noise is reduced.
Specifically, the circuit principle of the second operational amplifier is as follows:
The source of the field effect tube M6, the source of the field effect tube M7, the source of the field effect tube M8 and the source of the field effect tube M9 are connected with power supply voltage, the drain of the field effect tube M7 is connected with the drain of the field effect tube M11, the drain of the field effect tube M8 is connected with the drain of the field effect tube M12, the grid of the field effect tube M6 is connected with the grid of the field effect tube M8, the source of the field effect tube M7 is connected with the source of the field effect tube M9, a resistor and a capacitor are connected in series between the grid of the field effect tube M7 and the drain, a resistor and a capacitor are connected in series between the grid of the field effect tube M8 and the drain of the field effect tube M10, the grid of the field effect tube M6 is connected with the drain of the field effect tube M6, the drain of the field effect tube M6 is also connected with the drain of the field effect tube M9, the source of the field effect tube M10 is connected with the source of the field effect tube M13, the grid of the long effect tube M11 is connected with the grid of the field effect tube M10, and the grid of the field effect tube M13 is connected with the grid of the field effect tube M13, and the grid of the output of the field effect tube M13 is connected with the grid of the field effect tube M13.
The drain electrode of the field effect tube M14 is respectively connected with the source electrode of the field effect tube M10 and the source electrode of the field effect tube M13, the source electrode of the field effect tube M14 is grounded, the grid electrode of the field effect tube M14 is connected with the amplified electric signal, the drain electrode of the field effect tube M15 is respectively connected with the source electrode of the field effect tube M11 and the source electrode of the field effect tube M12, the source electrode of the field effect tube M15 is grounded, and the grid electrode of the field effect tube M15 is connected with the second common-mode common-grid voltage V CMFB2.
As a preferred embodiment of the present application, the dc servo loop includes an input end and an output end, the input end of the dc servo loop is connected in parallel with the first operational amplifier through the third power amplifier, and the output end of the dc servo loop is electrically connected to the programmable gain amplifying-filtering circuit.
As a preferred embodiment of the present application, the feedback loop includes an input end and an output end, the input end of the feedback loop is electrically connected to the programmable gain amplifying-filtering circuit, and the output end of the feedback loop is connected in parallel to the first operational amplifier, so as to realize stable gain of the analog front-end circuit through the feedback loop, thereby ensuring linearity of the analog front-end circuit.
As a preferred embodiment of the present application, the analog front-end circuit further includes an impedance boosting loop, where the impedance boosting loop is connected in parallel with the amplifier, the dc servo loop and the feedback loop, and the impedance boosting loop is a switched capacitor circuit, and meets the requirement of a larger input impedance through the impedance boosting loop, and suppresses the spread data output by using the dc servo loop.
The application reduces noise and offset of the collected bioelectric signals by using chopper modulation through the low-noise amplifying circuit and provides additional open-loop gain and larger output swing, wherein the low-noise amplifying circuit adopts a capacitive coupling structure design, and realizes stable gain of the analog front-end circuit through a feedback loop. The low-pass filtering function is realized through the programmable gain amplifying-filtering circuit, the programmable gain is changed through the feedback ratio of the feedback loop so as to obtain different biological signals, wherein the programmable gain amplifying-filtering circuit mainly adopts the full-differential amplifying circuit to improve the gain and larger input and output swing of the analog front-end circuit, thereby ensuring the precision and the dynamic range of the analog front-end circuit, and the stability of the programmable gain amplifying-filtering circuit is improved by adding the Miller compensation into the filtering circuit.
The application also provides a signal acquisition analog chip applied to the nerve probe, which comprises a detection electrode, a detection signal output end and the signal acquisition analog front-end circuit, wherein the signal acquisition analog front-end circuit is connected with the detection electrode and the detection signal output end respectively.
The biological nerve electric signal is obtained by using the detection electrode, and the biological nerve electric signal is amplified and noise reduced by using the analog front-end circuit, so that the common-mode interference signal is inhibited, and the quality of the biological nerve electric signal is improved.
The application also provides a nerve probe, which comprises a control main board and an injection tube, wherein the control main board adopts the signal acquisition simulation chip; the injection tube is in communication connection with the control main board, and the movement of the injection tube is controlled by the control main board.
The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.
Claims (10)
1. A signal acquisition analog front-end circuit of a nerve probe, characterized by: comprising a low noise amplifier circuit and a programmable gain amplification-filter circuit, said low noise amplifier circuit and programmable gain amplification-filter circuit being connected, wherein,
The low-noise amplifier circuit comprises an amplifier, a direct current servo loop and a feedback loop, wherein the direct current servo loop and the feedback loop are both connected with the amplifier in parallel;
The programmable gain amplifying-filtering circuit comprises a programmable gain amplifying circuit and a filtering circuit, and the programmable gain amplifying circuit is connected with the filtering circuit;
The low noise amplifier circuit is used for amplifying an input electric signal and inhibiting interference signals in the amplified electric signal through the programmable gain amplifying-filtering circuit.
2. A signal acquisition analog front end circuit for a nerve probe as claimed in claim 1, wherein: the filter circuit comprises a first current mirror circuit, a second current mirror circuit, a third current mirror circuit, a fourth current mirror circuit, a field effect transistor M17, a field effect transistor M18, a field effect transistor M19 and a field effect transistor M20, wherein,
The first current mirror circuit and the second current mirror circuit are common-drain common-gate current mirrors, the third current mirror circuit and the fourth current mirror circuit are common-source common-gate current mirrors, the drain electrodes of the second current mirror circuit are electrically connected with the drain electrode of the third current mirror circuit, the source electrodes of the first current mirror circuit are connected with input voltage, and the source electrodes of the fourth current mirror circuit are grounded;
The grid electrode of the field effect transistor M17 and the grid electrode of the field effect transistor M18 are respectively connected with two drain electrodes of a transistor in the second current mirror circuit;
The source electrode of the field effect tube M17 and the source electrode of the field effect tube M18 are connected with input voltages;
The drain electrode of the field effect tube M17 is connected with the drain electrode of the field effect tube M19;
the drain electrode of the field effect tube M18 is connected with the drain electrode of the field effect tube M20;
The grid electrode of the field effect tube M19 is connected with the grid electrode of the field effect tube M20, and the source electrode of the field effect tube M19 and the source electrode of the field effect tube M20 are grounded.
3. A signal acquisition analog front end circuit for a nerve probe as claimed in claim 2, wherein: the programmable gain amplifying circuit comprises a fifth current mirror circuit, a field effect transistor M21 and a field effect transistor M22, wherein,
The source electrode of the field effect tube M21 is connected with an input voltage, the grid electrode of the field effect tube M21 is connected with the amplified electric signal, and the drain electrode of the field effect tube M21 is connected with the first current mirror circuit;
the source electrode of the field effect tube M22 is grounded, the grid electrode of the field effect tube M22 is connected with the amplified electric signal, and the drain electrode of the field effect tube M22 is grounded.
4. A signal acquisition analog front end circuit for a nerve probe as claimed in claim 3 wherein: the fifth current mirror circuit comprises a field effect transistor M501, a field effect transistor M502, a field effect transistor M51 and a field effect transistor M52, wherein,
The source electrode of the field effect transistor M501 is connected with the source electrode of the field effect transistor M502, and the connected node is also connected with the drain electrode of the field effect transistor M22;
The drain electrode of the field effect transistor M501 and the drain electrode of the field effect transistor M502 are respectively connected with two drain electrodes of the first current mirror circuit;
The grid electrode of the field effect tube M501 is connected with the signal positive input end, and the grid electrode of the field effect tube M502 is connected with the signal negative input end;
The source electrode of the field effect tube M51 is connected with the source electrode of the field effect tube M52 and is respectively connected with the drain electrode of the field effect tube M21, the drain electrode of the field effect tube M51 and the drain electrode of the field effect tube M52 are respectively connected with the two source electrodes of the third current mirror circuit, the grid electrode of the field effect tube M51 is connected with the signal positive input end, and the grid electrode of the field effect tube M52 is connected with the signal negative input end.
5. A signal acquisition analog front end circuit for a nerve probe as claimed in claim 1, wherein: the amplifier comprises a first amplifier and a second amplifier which are connected in series, wherein
The first amplifier comprises a first power amplifier and a first operational amplifier, and the first power amplifier is connected in series with the first operational amplifier;
the second amplifier comprises a second power amplifier and a second operational amplifier, and the second power amplifier and the second operational amplifier are connected in series.
6. The signal acquisition analog front end circuit of a nerve probe of claim 5, wherein: the direct current servo loop comprises an input end and an output end, the input end of the direct current servo loop is connected with the first operational amplifier in parallel through the third power amplifier, and the output end of the direct current servo loop is electrically connected with the programmable gain amplifying-filtering circuit.
7. The signal acquisition analog front-end circuit of a nerve probe of claim 6, wherein: the feedback loop comprises an input end and an output end, wherein the input end of the feedback loop is electrically connected with the programmable gain amplifying-filtering circuit, and the output end of the feedback loop is connected with the first operational amplifier in parallel.
8. The signal acquisition analog front end circuit of a nerve probe of claim 7, wherein: the analog front-end circuit further comprises an impedance improving loop, the impedance improving loop is respectively connected with the amplifier, the direct current servo loop and the feedback loop in parallel, and the impedance improving loop is a switched capacitor circuit.
9. A signal acquisition analog chip applied to a nerve probe is characterized in that: a signal acquisition analog front-end circuit comprising a detection electrode, a detection signal output, and any of claims 1-8, the signal acquisition analog front-end circuit being connected to the detection electrode and the detection signal output, respectively.
10. A nerve probe, characterized in that: the device comprises a control main board and an injection tube, wherein the control main board adopts the signal acquisition analog chip as claimed in claim 9;
the injection tube is in communication connection with the control main board, and the movement of the injection tube is controlled by the control main board.
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