Micro current source system

Abstract

The invention relates to the technical field of micro-current, and particularly provides a micro-current source system. The technical problem that an existing micro-current source technology is low in stability and precision is solved. Therefore, the micro-current source system comprises a current source module and a control module, the control module is used for acquiring a control signal and sending the control signal to the current source module; the current source module is used for outputting corresponding micro current based on the control signal; wherein the current source module comprises a voltage generator, a negative feedback regulation module and a transimpedance I / V conversion module, and the voltage generator is used for receiving a control signal, comparing the control signal with a preset reference voltage, generating a direct-current voltage signal and sending the direct-current voltage signal to the negative feedback regulation module; the negative feedback regulation module is used for acquiring a feedback signal of the transimpedance I / V conversion module, regulating the direct-current voltage signal based on the feedback signal and outputting a micro-current; the transimpedance I / V conversion module is used for converting the micro current to obtain a corresponding feedback signal and sending the feedback signal to the negative feedback adjustment module.

Description

Technical Field

[0001] This application relates to the field of microcurrent technology, and particularly to a microcurrent source system. Background Art

[0002] In the field of new energy vehicles, the wide application of power electronics and semiconductor devices is crucial for improving vehicle performance, energy efficiency, and intelligence level. In the research, manufacturing, and detection processes of these sensor devices, high-precision microcurrent sources play an indispensable role. The generation of microcurrent requires converting voltage signals into current signals using VI conversion, mainly including resistive microcurrent sources, capacitive microcurrent sources, etc. However, the existing microcurrent source technologies have some limitations. For example, the resistive microcurrent source has a high-resistance time constant, poor stability, high noise, and the load size has a great impact on the output, resulting in a high output uncertainty. Although the accuracy of the capacitive microcurrent source is higher than that of the resistive microcurrent source, its continuous output time is limited and it is difficult to meet the requirement of long-term stable operation.

[0003] Correspondingly, a new microcurrent source solution is needed in this field to solve the above problems. Summary of the Invention

[0004] In order to overcome the above defects, this application is proposed to solve or at least partially solve the technical problems of low stability and accuracy existing in the existing microcurrent source technology.

[0005] In a first aspect, a microcurrent source system is provided. The microcurrent source system includes: a current source module and a control module; the control module is configured to obtain a control signal and send it to the current source module; the current source module is configured to output a corresponding microcurrent based on the control signal; wherein the current source module includes a voltage generator, a negative feedback adjustment module, and a transresistance I / V conversion module. The voltage generator is configured to receive the control signal, compare the control signal with a preset reference voltage, generate a DC voltage signal, and send it to the negative feedback adjustment module; the negative feedback adjustment module is configured to obtain the feedback signal of the transresistance I / V conversion module and adjust the DC voltage signal based on the feedback signal to output a microcurrent; the transresistance I / V conversion module is configured to convert the microcurrent output by the negative feedback adjustment module to obtain a corresponding feedback signal and send it to the negative feedback adjustment module.

[0006] In a technical solution of the above micro-current source system, the transimpedance I / V conversion module includes a first amplifier, a multi-stage amplifier, and a sampling resistor; the inverting input terminal of the first amplifier is respectively connected to one end of the sampling resistor, the inverting input terminal of the multi-stage amplifier, and the output terminal of the negative feedback adjustment module, the non-inverting input terminal of the first amplifier is grounded, and the output terminal is electrically connected to the other end of the sampling resistor; the non-inverting input terminal of the multi-stage amplifier is respectively connected to the output terminal of the first amplifier and the other end of the sampling resistor, and the output terminal is connected to the first input terminal of the negative feedback adjustment module.

[0007] In a technical solution of the above micro-current source system, the multi-stage amplifier includes a second amplifier and a third amplifier; the number of the sampling resistors is multiple, and the multiple sampling resistors are connected in parallel; the transimpedance I / V conversion module further includes multiple switches, a first feedback resistor, and a second feedback resistor, and the sampling resistor, the first feedback resistor, and the second feedback resistor form a T-type feedback network; each switch is connected in series with one of the sampling resistors to control the multiple sampling resistors by controlling the turn-off of the multiple switches; wherein, one ends of the multiple sampling resistors are all connected to the output terminal of the negative feedback adjustment module, the inverting input terminal of the first amplifier, and the inverting input terminal of the second amplifier, the other ends of the multiple sampling resistors are all connected to one ends of the corresponding switches, and the other ends of the multiple switches are all connected to the output terminal of the first amplifier and the non-inverting input terminal of the second amplifier; the non-inverting input terminal of the second amplifier is connected to the output terminal of the first amplifier, and the output terminal is connected to the non-inverting input terminal of the third amplifier; the output terminal of the third amplifier is connected to the first input terminal of the negative feedback adjustment module; one end of the first feedback resistor is connected to the inverting input terminal of the third amplifier, and the other end is connected to the output terminal of the third amplifier and the first input terminal of the negative feedback adjustment module; one end of the second feedback resistor is connected to the inverting input terminal of the third amplifier, and the other end is grounded.

[0008] In a technical solution of the above micro-current source system, the transimpedance I / V conversion module further includes a first capacitor; the first capacitor is connected in parallel with the multiple sampling resistors; one end of the first capacitor is connected to one ends of the multiple sampling resistors, the inverting input terminal of the first amplifier, and the output terminal of the negative feedback adjustment module, and the other end is connected to the other end of the switch and the output terminal of the first amplifier.

[0009] In a technical solution of the above micro-current source system, the voltage generator includes a digital-to-analog conversion module, a voltage follower, and a programmable voltage divider; an input end of the digital-to-analog conversion module is connected to an output end of the control module, an output end is connected to an input end of the voltage follower, an output end of the voltage follower is electrically connected to an input end of the programmable voltage divider, and an output end of the programmable voltage divider is connected to a second input end of the negative feedback adjustment module.

[0010] In a technical solution of the above micro-current source system, the negative feedback adjustment module includes a first resistor, a second resistor, a second capacitor, and a fourth amplifier; one end of the first resistor is connected to an output end of the programmable voltage divider, and the other end is respectively connected to one end of the second capacitor and an inverting input end of the fourth amplifier; the other end of the second capacitor is respectively connected to an output end of the fourth amplifier and one end of the second resistor; a non-inverting input end of the fourth amplifier is connected to an output end of the multi-stage amplifier; the other end of the second resistor is respectively connected to an inverting input end of the first amplifier, the one end of the sampling resistor, and an inverting input end of the multi-stage amplifier.

[0011] In a technical solution of the above micro-current source system, the current source module further includes a voltage digitization module; an input end of the voltage digitization module is connected to an output end of the multi-stage amplifier, and an output end is connected to a first input end of the control module; the voltage digitization module is configured to perform analog-to-digital conversion processing on a feedback signal from the transimpedance I / V conversion module by using a multi-slope integration digitization method to obtain a digital signal and send the digital signal to the control module; and / or, the current source module further includes a protection module; an input end of the protection module is connected to an output end of the first amplifier, and an output end is connected to a second input end of the control module; the protection module is configured to perform at least one of overload protection, overcurrent protection, open-circuit protection, and temperature protection on the current source module, and / or generate a corresponding alarm message to be sent to the control module when an abnormal situation occurs in the current source module.

[0012] In a technical solution of the above micro-current source system, the control module includes a data processing module, a data interface module, and a display module. The input and output ends of the data processing module are electrically connected to the input and output ends of the data interface module and the input and output ends of the display module respectively; the data processing module includes a programmable gate array, a microprocessor, and a memory; the output end of the programmable gate array is connected to the input end of the voltage generator, the first input end is connected to the output end of the voltage digitization module, the second input end is connected to the output end of the protection module, and the input and output ends of the programmable gate array, the first input and output ends of the microprocessor, and the output and output ends of the memory are connected through a bus; the second input and output ends of the microprocessor are connected to the input and output ports of the data interface module, and the third input and output ends are connected to the input and output ports of the display module; the data processing module is configured to receive the control instruction of the display module, and determine a control signal based on the control instruction and send it to the current source module, so that the current source module outputs a corresponding micro-current based on the control signal, and receive the digital signal fed back by the current source module, and determine a display signal based on the digital signal and send it to the display module; and / or, the display module is configured to obtain a control instruction and send the control instruction to the microprocessor, and receive and display the display signal of the microprocessor; and / or, the data interface module is configured to provide an interface for the data processing module to connect to an external device.

[0013] In a technical solution of the above micro-current source system, the output end of the programmable gate array is connected to the input end of the voltage generator, the first input end of the programmable gate array is connected to the output end of the voltage digitization module, and the second input end of the programmable gate array is connected to the output end of the protection module, all of which are connected in an isolation connection manner, where the isolation connection manner includes transformer isolation and / or opto-isolator isolation.

[0014] In a technical solution of the above micro-current source system, the micro-current source system includes a power supply module, and the power supply module includes a switching power supply module and a DC conversion module; the input end of the switching power supply module is connected to an AC power supply, and the output end is connected to the input end of the DC conversion module; the output end of the DC conversion module is electrically connected to the control module and the current source module; the switching power supply module is configured to access an AC power supply, convert the input AC power into DC power, and transfer the converted DC power to the DC conversion module; the DC conversion module is configured to perform secondary conversion on the DC power to obtain low-noise DC power to supply power to the control module and the current source module.

[0015] One or more of the above technical solutions of the present application have at least one or more of the following beneficial effects:

[0016] The present application provides a micro-current source system, which includes a current source module and a control module. The control module is configured to obtain a control signal and send it to the current source module. The current source module is configured to output a corresponding micro-current based on the control signal. Wherein the current source module includes a voltage generator, a negative feedback regulation module, and a transimpedance I / V conversion module. The voltage generator is configured to receive the control signal, compare the control signal with a preset reference voltage, generate a DC voltage signal, and send it to the negative feedback regulation module. The negative feedback regulation module is configured to obtain the feedback signal of the transimpedance I / V conversion module, regulate the DC voltage signal based on the feedback signal, and output a micro-current. The transimpedance I / V conversion module is configured to convert the micro-current output by the negative feedback regulation module to obtain a corresponding feedback signal and send it to the negative feedback regulation module. In the present application, the control module obtains the control signal, and the current source module combines the control signal and the feedback signal of the transimpedance I / V conversion module to achieve closed-loop control, thereby outputting a micro-current corresponding to the control signal, effectively ensuring the stability and accuracy of the output micro-current, reducing errors, and improving the output precision. Description of the Drawings

[0017] Referring to the drawings, the disclosure of the present application will become more understandable. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the protection scope of the present application. Among them:

[0018] Figure 1 is a schematic diagram of the main structure of a micro-current source system according to an embodiment of the present application;

[0019] Figure 2 is a schematic diagram of the detailed structure of a micro-current source system according to an embodiment of the present application;

[0020] Figure 3 is a schematic diagram of the conversion principle of a transimpedance I / V conversion module according to an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of the principle of a voltage generator according to an embodiment of the present application;

[0022] Figure 5 is a schematic diagram of the principle of a voltage digitization module according to an embodiment of the present application;

[0023] Figure 6 is a schematic diagram of the micro-current output model of a current source module according to an embodiment of the present application;

[0024] Figure 7 is a schematic diagram of the working principle of a power supply module according to an embodiment of the present application.

[0025] Reference numerals:

[0026] 1: First amplifier; 2: Second amplifier; 3: Third amplifier; 4: Sampling resistor; 5: Switch; 6: First capacitor; 7: First feedback resistor; 8: Second feedback resistor; 9: First resistor; 10: Second capacitor; 11: Fourth amplifier; 12: Second resistor. Detailed implementation manners

[0027] Some implementation manners of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these implementation manners are only used to explain the technical principle of the present application and are not intended to limit the protection scope of the present application.

[0028] In the description of the present application, "module" and "processor" may include hardware, software, or a combination of both. A module may include a hardware circuit, various suitable sensors, communication ports, memories, and may also include a software part, such as program code, or a combination of software and hardware. A processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, in hardware, or in a combination of both. A computer-readable storage medium includes any suitable medium that can store program code, such as a magnetic disk, a hard disk, an optical disk, a flash memory, a read-only memory, a random access memory, and so on. The term "A and / or B" represents all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one A or B" or "at least one of A and B" has a meaning similar to "A and / or B" and may include only A, only B, or A and B. The singular terms "a" and "this" may also include the plural form.

[0029] Refer to the attached Figure 1 , Figure 1 is a schematic diagram of the main structure of a microcurrent source system according to an embodiment of the present application. As Figure 1As shown in the figure, a micro-current source system in an embodiment of the present application includes: a current source module and a control module; the control module is configured to obtain a control signal and send it to the current source module; the current source module is configured to output a corresponding micro-current based on the control signal; wherein the current source module includes a voltage generator, a negative feedback adjustment module, and a transresistance I / V conversion module, the voltage generator is configured to receive the control signal, compare the control signal with a preset reference voltage, generate a DC voltage signal, and send it to the negative feedback adjustment module; the negative feedback adjustment module is configured to obtain a feedback signal of the transresistance I / V conversion module and adjust the DC voltage signal based on the feedback signal to output a micro-current; the transresistance I / V conversion module is configured to convert the micro-current output by the negative feedback adjustment module to obtain a corresponding feedback signal and send it to the negative feedback adjustment module.

[0030] Specifically, the micro-current source system includes a control module and a current source module. The control module is used to interact with an external device, receive a control signal, which can be a signal such as a set current amplitude or a custom-programmed test current. The control module sends the control signal to the current source module and controls the current source module to output a micro-current as required. The control module also receives in real time the digital signal of the output micro-current fed back by the current source module, processes the digital signal, and then sends it to a display device for display.

[0031] In one embodiment, the transresistance I / V conversion module includes a first amplifier, a multi-stage amplifier, and a sampling resistor; the inverting input terminal of the first amplifier is respectively connected to one end of the sampling resistor, the inverting input terminal of the multi-stage amplifier, and the output terminal of the negative feedback adjustment module. The non-inverting input terminal of the first amplifier is grounded, and the output terminal is electrically connected to the other end of the sampling resistor; the non-inverting input terminal of the multi-stage amplifier is respectively connected to the output terminal of the first amplifier and the other end of the sampling resistor, and the output terminal is connected to the first input terminal of the negative feedback adjustment module.

[0032] Specifically, the transresistance I / V conversion module is used to convert the micro-current on the output loop of the negative feedback adjustment module to obtain a corresponding feedback signal, which is a voltage signal. When the micro-current signal is very small, such as in pA or fA level, and it needs to be amplified to a mV-level voltage for easy measurement, a high-resistance resistor can be used as the sampling resistor, and its value can be 10 9 ~10 14 Ohms. Then, the feedback signal is further amplified by the multi-stage amplifier to ensure that the feedback signal meets the requirements of subsequent processing.

[0033] In one embodiment, the multi-stage amplifier includes a second amplifier and a third amplifier; the number of sampling resistors is multiple, and the multiple sampling resistors are connected in parallel; the transimpedance I / V conversion module further includes multiple switches, a first feedback resistor, and a second feedback resistor, and the sampling resistors, the first feedback resistor, and the second feedback resistor form a T-type feedback network; each switch is connected in series with one of the sampling resistors to control the multiple sampling resistors by turning off the multiple switches; wherein, one ends of the multiple sampling resistors are all connected to the output end of the negative feedback adjustment module, the inverting input end of the first amplifier, and the inverting input end of the second amplifier, the other ends of the multiple sampling resistors are all connected to one ends of the corresponding switches, and the other ends of the multiple switches are all connected to the output end of the first amplifier and the non-inverting input end of the second amplifier; the non-inverting input end of the second amplifier is connected to the output end of the first amplifier, and the output end is connected to the non-inverting input end of the third amplifier; the output end of the third amplifier is connected to the first input end of the negative feedback adjustment module; one end of the first feedback resistor is connected to the inverting input end of the third amplifier, and the other end is connected to the output end of the third amplifier and the first input end of the negative feedback adjustment module; one end of the second feedback resistor is connected to the inverting input end of the third amplifier, and the other end is grounded.

[0034] Specifically, the transimpedance I / V conversion module further includes multiple switches corresponding to the number of sampling resistors, a first feedback resistor, and a second feedback resistor. The sampling resistors include multiple ones, and the multiple sampling resistors are connected in parallel. Each sampling resistor corresponds to one switch. The detailed structure of the transimpedance I / V conversion module is as Figure 2 shown.

[0035] The multiple sampling resistors form a sampling resistor network to handle weak currents of different ranges. Sampling resistors 41, 42... 49 are connected in parallel. Each sampling resistor corresponds to a different current range (100 mA to 2 nA). Each sampling resistor is equipped with a switch for selecting a different range. The sampling resistors, the first feedback resistor, and the second feedback resistor form a T-type network. The amplification factor is increased by selecting appropriate ratios of the first feedback resistor and the second feedback resistor.

[0036] In some specific embodiments, the corresponding relationships among different current ranges, resistances, and voltages are shown in Table 1. Table 1

[0037] The conversion principle of the transimpedance I / V conversion module is as Figure 3As shown, when it is necessary to set the output current I = 100 fA, the 2 nA range is selected. At this time, the microprocessor controls the voltage generator to generate a voltage of 10 μV (when the full-scale output is 2 nA, the voltage is 2 V), and after passing through the integrator of the negative feedback adjustment module, U1 = 1 μV is obtained, and a current of 100 fA is generated by applying it to the sampling resistor R9.

[0038] In one embodiment, the transimpedance I / V conversion module further includes a first capacitor; the first capacitor is connected in parallel with a plurality of the sampling resistors; one end of the first capacitor is connected to one end of the plurality of sampling resistors, the inverting input terminal of the first amplifier, and the output terminal of the negative feedback adjustment module, and the other end is connected to the other end of the switch and the output terminal of the first amplifier.

[0039] Specifically, the transimpedance I / V conversion module further includes a first capacitor, which is connected in parallel with a plurality of sampling resistors and is used for filtering and protecting the sampling resistors, reducing the influence of high-frequency noise on the signal, and helping to improve the accuracy and stability of the transimpedance I / V conversion module when processing signals.

[0040] In one embodiment, the voltage generator includes a digital-to-analog conversion module, a voltage follower, and a programmable voltage divider; the input terminal of the digital-to-analog conversion module is connected to the output terminal of the control module, the output terminal is connected to the input terminal of the voltage follower, the output terminal of the voltage follower is electrically connected to the input terminal of the programmable voltage divider, and the output terminal of the programmable voltage divider is connected to the second input terminal of the negative feedback adjustment module.

[0041] Specifically, the voltage generator includes a digital-to-analog conversion module, a voltage follower, and a programmable voltage divider. The voltage generator is used to receive a control signal, which is a digital signal, convert the control signal into an analog voltage signal via the digital-to-analog conversion module, and then adjust and filter it through the voltage follower and the programmable voltage divider, and finally output a stable analog voltage signal.

[0042] In some specific embodiments, the digital-to-analog conversion module can adopt a DAC chip solution. The principle of the voltage generator adopting the DAC chip solution is as Figure 4 shown. The digital-to-analog conversion module can adopt a 16-bit DAC chip. The digital-to-analog conversion module receives the control signal of the control module, which is a digital signal. The digital-to-analog conversion module compares the control signal with a preset reference voltage and converts the control signal into a corresponding analog voltage signal.

[0043] The preset reference voltage serves as the reference voltage for the digital-to-analog conversion module, ensuring the accuracy of the analog voltage signal output by the digital-to-analog conversion module. The preset reference voltage can be determined according to factors such as the resolution required by the system, measurement accuracy, supply voltage, operating temperature range, etc. For example, an XFET type voltage reference can be selected as the preset reference voltage.

[0044] The voltage follower is used to buffer and amplify the voltage signal output by the digital-to-analog conversion module and transfer it to the programmable voltage divider.

[0045] The programmable voltage divider is used to perform proportional voltage division on the voltage output by the voltage follower to achieve the key to regulating the output of weak current. The programmable voltage divider can adopt resistor voltage division, DAC converter voltage division, or pulse width modulation voltage division.

[0046] In one embodiment, the negative feedback regulation module includes a first resistor, a second resistor, a second capacitor, and a fourth amplifier; one end of the first resistor is connected to the output end of the programmable voltage divider, and the other end is respectively connected to one end of the second capacitor and the inverting input end of the fourth amplifier; the other end of the second capacitor is respectively connected to the output end of the fourth amplifier and one end of the second resistor; the non-inverting input end of the fourth amplifier is connected to the output end of the multi-stage amplifier; the other end of the second resistor is respectively connected to the inverting input end of the first amplifier, the one end of the sampling resistor, and the inverting input end of the multi-stage amplifier.

[0047] Specifically, the real-time output micro-current is collected and converted through a transimpedance I / V conversion module to obtain a feedback signal. The negative feedback regulation module is used to acquire the feedback signal, compare the feedback signal with the DC voltage signal output by the voltage generator to generate an error voltage, which is integrally amplified to form an amplitude regulation power signal for the output micro-current, adjust the output amplitude of the micro-current, and then adjust the real-time micro-current output through the power amplifier output circuit. Then, the output micro-current is sampled again, and this closed-loop cycle is repeated until no error voltage and amplitude regulation voltage signal are generated, thereby ensuring the stability of the micro-current output.

[0048] In one embodiment, the current source module further includes a voltage digitization module; the input end of the voltage digitization module is connected to the output end of the multi-stage amplifier, and the output end is connected to the first input end of the control module; the voltage digitization module is used to perform analog-to-digital conversion processing on the feedback signal from the transimpedance I / V conversion module using the multi-slope integration digitization method to obtain a digital signal and send the digital signal to the control module.

[0049] Specifically, the voltage digitization module uses the multi-slope integration voltage digitization technology to implement A / D conversion. The circuit principle of the voltage digitization module is as Figure 5As shown. The multi-slope integrating voltage digitization technology mainly changes the use of positive and negative reference voltages continuously during the sampling stage, so as to achieve the purpose that the integrator output will not saturate. The main working process is as follows: first, the measured voltage is integrated for a time t 0 Then, the measured voltage U X and the reference voltage U Ref are integrated for a time t1. Assuming U Ref >U X , at this time, the integrator output is a downward slope. After t1 ends, the zero-crossing comparator judges whether the integrator output crosses zero. If it crosses zero, after the integrator integrates the measured voltage for a time t2, it integrates (U X -U Ref ) for a time t1; if it does not cross zero, it still integrates the voltage (-U X +U Ref ) for a downward slope integration until the integrator output crosses zero, and then performs the above operations, that is, integrates (-U X -U Ref ) for a time t1, and then the comparator makes a zero-crossing judgment again. Repeat this process until the sampling stage t1 ends. Then disconnect the measured voltage and apply the required voltage to the integrator to make the integrator output cross zero quickly. It can be obtained that: U x =(U ref / t 1 )·[(m - n)t 1 ±t 3

[0050] The time required for one conversion by the multi-slope integrating digitization technology is slightly longer than the sampling time. Compared with the ordinary integrating A / D converter, it is faster, and can also reduce the requirement for the dynamic range of the integrator, and has a greater improvement in performance such as accuracy, linearity, and resolution, and is very suitable for the measurement scenario of weak current.

[0051] In one embodiment, the current source module further includes a protection module; the input end of the protection module is connected to the output end of the first amplifier, and the output end is connected to the second input end of the control module; the protection module is used to perform at least one of overload protection, overcurrent protection, open-circuit protection, and temperature protection on the current source module, and / or generate corresponding alarm information and send it to the control module when an abnormal situation occurs in the current source module.

[0052] ​Specifically, the protection module can perform overload protection, overcurrent protection, open-circuit protection, and temperature monitoring protection on the current source module. After any protection is executed in case of an abnormal situation, the abnormal situation is converted into an alarm message in digital signal form and fed back to the control module. The control module processes the alarm message and feeds it back to the operator through the display module.

[0053] In some embodiments, the current source module of the present application further includes an active equipotential noise suppression and anti-leakage module. The micro-current output model of the current source module is as Figure 6 shown, Figure 6 which shows various noises and currents generated during the measurement of the micro-current output by the current source module. I SE represents the noise generated inside the current source module itself. I CE represents the noise current generated by the interconnection between the instrument and the current source module. Leakage, piezoelectricity, triboelectric effect, or dielectric absorption will all generate noise current. I RE is caused by the thermal noise of the resistor. In this embodiment, a constant-temperature intelligent regulation technology is adopted to suppress the thermal noise of the resistor. I SH is the current flowing through R SH .

[0054] For external noises such as radiation noise and electromagnetic noise, equipotential shielding can be performed by adding a metal shielding box to reduce interference such as radiation, static electricity, and electromagnetism.

[0055] For leakage, the input stage of the current can use a material with a high insulation coefficient, such as polytetrafluoroethylene (Teflon), and adopt an automatic equipotential tracking protection technology to surround the input path and all sensitive feedback devices with a protection ring and drive them by a protection voltage to form an equipotential region, which can effectively prevent leakage current and also interrupt capacitive coupling.

[0056] In some embodiments, since the collected micro-current signal is very small, the present application adopts a double shielding structure of an aluminum inner shielding body and an outer iron shielding box to suppress electromagnetic interference.

[0057] In one embodiment, the control module includes a data processing module, a data interface module, and a display module. The input and output ends of the data processing module are electrically connected to the input and output ends of the data interface module and the input and output ends of the display module respectively. The data processing module includes a field programmable gate array, a microprocessor, and a memory. The output end of the field programmable gate array is connected to the input end of the voltage generator. The first input end is connected to the output end of the voltage digitization module, and the second input end is connected to the output end of the protection module. The input and output ends of the field programmable gate array, the first input and output end of the microprocessor, and the output and output ends of the memory are connected through a bus. The second input and output end of the microprocessor is connected to the input and output ports of the data interface module, and the third input and output end is connected to the input and output ports of the display module. The data processing module is configured to receive a control instruction from the display module, and determine a control signal based on the control instruction and send it to the current source module, so that the current source module outputs a corresponding microcurrent based on the control signal, and receive a digital signal fed back by the current source module, and determine a display signal based on the digital signal and send it to the display module; and / or, the display module is configured to obtain a control instruction and send the control instruction to the microprocessor, and receive and display the display signal from the microprocessor; and / or, the data interface module is configured to provide an interface for the data processing module to connect to an external device.

[0058] Specifically, the data processing module includes a field programmable gate array (FPGA), a microprocessor (MCU), and a memory. The data processing module is configured to receive a control instruction from the display module, such as controlling the wideband power source to adjust the frequency, amplitude, and waveform output, and determine a control signal based on the control instruction and send it to the current source module, so that the current source module outputs a corresponding microcurrent based on the control signal.

[0059] The data processing module is further configured to receive in real time the digital signal fed back by the voltage digitization module, calculate the display signal corresponding to the digital signal according to an integration algorithm, and transmit it to the display module for display.

[0060] The data interface module includes communication interfaces such as USB, RS232, and Ethernet ports, and can be connected to an external device using a corresponding data cable, and cooperate with a dedicated test software to analyze microcurrent data.

[0061] The display module is used for data interaction, and can display relevant data values set by the user or the display signal corresponding to the microcurrent output by the current source module. The display module is also used for the user to set the output microcurrent through the display module.

[0062] In one embodiment, the output terminal of the programmable gate array is connected to the input terminal of the voltage generator, the first input terminal of the programmable gate array is connected to the output terminal of the voltage digitization module, and the second input terminal of the programmable gate array is connected to the output terminal of the protection module by an isolation connection method, where the isolation connection method includes transformer isolation and / or opto-isolator isolation.

[0063] Specifically, to avoid signal interference, the control module and the current source module are connected by an isolation connection method. The isolation connection method can be transformer isolation or opto-isolator isolation. Opto-isolator isolation is suitable for the transmission of digital signals and low-frequency analog signals, while transformer isolation is suitable for the transmission of high-frequency signals and power signals. The isolation connection method can be selected according to actual needs.

[0064] In one embodiment, the micro-current source system includes a power supply module, and the power supply module includes a switching power supply module and a DC conversion module; the input terminal of the switching power supply module is connected to an AC power supply, and the output terminal is connected to the input terminal of the DC conversion module; the output terminal of the DC conversion module is electrically connected to the control module and the current source module; the switching power supply module is used to access an AC power supply, convert the input AC power into DC power, and transmit the converted DC power to the DC conversion module; the DC conversion module is used to perform secondary conversion on the DC power to obtain low-noise DC power to supply power to the control module and the current source module.

[0065] Specifically, the power supply module is powered by an AC power supply. Therefore, it is necessary to first convert the input AC power into DC power and then obtain the DC operating levels required by each module through level conversion. The working principle of the power supply module is as Figure 7 shown. The commercial power AC 220V is first converted into DC power by the switching power supply module and then converted into the required DC power by the DC conversion module. The switching power supply module can adopt a voltage-adjustable switching power supply, and the DC conversion module can adopt a low-dropout linear voltage regulator (LDO).

[0066] So far, the technical solution of the present application has been described in conjunction with one embodiment shown in the drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principle of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A micro current source system, characterized in that: The micro-current source system comprises: a current source module and a control module; the control module is used to obtain a control signal and send it to the current source module; the current source module is used to output a corresponding micro-current based on the control signal; wherein the current source module comprises a voltage generator, a negative feedback regulation module and a transimpedance I / V conversion module, the voltage generator is used to receive the control signal, compare the control signal with a preset reference voltage, generate a DC voltage signal, and send it to the negative feedback regulation module; The negative feedback regulation module is used to obtain the feedback signal of the transimpedance I / V conversion module, and regulate the DC voltage signal based on the feedback signal to output a micro current; The transimpedance I / V conversion module is used to convert the micro-current output by the negative feedback regulation module, obtain a corresponding feedback signal, and send it to the negative feedback regulation module.

2. The micro current source system according to claim 1, characterized in that: The transimpedance I / V conversion module includes a first amplifier, a multi-stage amplifier and a sampling resistor; The inverting input terminal of the first amplifier is respectively connected to one end of the sampling resistor, the inverting input terminal of the multi-stage amplifier and the output terminal of the negative feedback regulation module, the non-inverting input terminal of the first amplifier is grounded, and the output terminal is electrically connected to the other end of the sampling resistor; The in-phase input terminal of the multi-stage amplifier is electrically connected to the output terminal of the first amplifier and the other end of the sampling resistor respectively, and the output terminal is connected to the first input terminal of the negative feedback regulation module.

3. The micro current source system according to claim 2, characterized in that: The multi-stage amplifier includes a second amplifier and a third amplifier; the number of the sampling resistors is multiple, and the multiple sampling resistors are connected in parallel; The transimpedance I / V conversion module further includes a plurality of switches, a first feedback resistor and a second feedback resistor, and the sampling resistor, the first feedback resistor and the second feedback resistor form a T-type feedback network; Each switch is connected in series with one of the sampling resistors, so as to realize control of the multiple sampling resistors by controlling the shutdown of the multiple switches; wherein the one ends of the multiple sampling resistors are connected to the output end of the negative feedback regulation module, the inverting input end of the first amplifier, and the inverting input end of the second amplifier, the other ends of the multiple sampling resistors are connected to one end of the corresponding switch, and the other ends of the multiple switches are connected to the output end of the first amplifier and the non-inverting input end of the second amplifier; The in-phase input terminal of the second amplifier is connected to the output terminal of the first amplifier, and the output terminal is connected to the in-phase input terminal of the third amplifier; The output end of the third amplifier is connected to the first input end of the negative feedback regulation module; One end of the first feedback resistor is connected to the inverting input end of the third amplifier, and the other end is connected to the output end of the third amplifier and the first input end of the negative feedback regulation module; One end of the second feedback resistor is connected to the inverting input terminal of the third amplifier, and the other end is grounded.

4. The micro-current source system according to claim 3, characterized in that: The transimpedance I / V conversion module also includes a first capacitor; the first capacitor is connected in parallel with the multiple sampling resistors; one end of the first capacitor is connected to one end of the multiple sampling resistors, the reverse input end of the first amplifier, and the output end of the negative feedback regulation module, and the other end is connected to the other end of the switch and the output end of the first amplifier.

5. The micro-current source system according to claim 2, characterized in that: The voltage generator includes a digital-to-analog conversion module, a voltage follower and a programmable voltage divider; the input end of the digital-to-analog conversion module is connected to the output end of the control module, the output end is connected to the input end of the voltage follower, the output end of the voltage follower is electrically connected to the input end of the programmable voltage divider, and the output end of the programmable voltage divider is connected to the second input end of the negative feedback regulation module.

6. The micro-current source system according to claim 5, characterized in that: The negative feedback regulation module includes a first resistor, a second resistor, a second capacitor, and a fourth amplifier; One end of the first resistor is connected to the output end of the programmable voltage divider, and the other end is connected to one end of the second capacitor and the inverting input end of the fourth amplifier respectively; The other end of the second capacitor is connected to the output end of the fourth amplifier and one end of the second resistor respectively; The in-phase input terminal of the fourth amplifier is connected to the output terminal of the multi-stage amplifier; The other end of the second resistor is respectively connected to the inverting input end of the first amplifier, the one end of the sampling resistor, and the inverting input end of the multi-stage amplifier.

7. The micro-current source system according to claim 2, characterized in that: The current source module further includes a voltage digitization module; the input end of the voltage digitization module is connected to the output end of the multi-stage amplifier, and the output end is connected to the first input end of the control module; The voltage digitization module is used to adopt a multi-slope integral digitization method to perform analog-to-digital conversion processing on the feedback signal from the transimpedance I / V conversion module to obtain a digital signal, and send the digital signal to the control module; and / or, The current source module further includes a protection module; the input end of the protection module is connected to the output end of the first amplifier, and the output end of the protection module is connected to the second input end of the control module; The protection module is used to perform at least one of overload protection, overcurrent protection, open circuit protection and temperature protection on the current source module, and / or generate corresponding alarm information and send it to the control module when an abnormal situation occurs in the current source module.

8. The micro-current source system according to claim 7, characterized in that: The control module includes a data processing module, a data interface module and a display module, and the input and output ends of the data processing module are electrically connected to the input and output ends of the data interface module and the input and output ends of the display module respectively; The data processing module includes a programmable gate array, a microprocessor and a memory; The output end of the programmable gate array is connected to the input end of the voltage generator, the first input end is connected to the output end of the voltage digitization module, the second input end is connected to the output end of the protection module, and the input and output ends of the programmable gate array, the first input and output ends of the microprocessor, and the output and output ends of the memory are connected via a bus; The second input / output terminal of the microprocessor is connected to the input / output port of the data interface module, and the third input / output terminal is connected to the input / output port of the display module; The data processing module is used to receive the control instruction of the display module, and determine the control signal based on the control instruction and send it to the current source module, so that the current source module outputs the corresponding microcurrent based on the control signal, and receive the digital signal fed back by the current source module, and determine the display signal based on the digital signal and send it to the display module; and / or, The display module is used to obtain control instructions, send the control instructions to the microprocessor, and receive display signals from the microprocessor for display; and / or, The data interface module is used to provide an interface for the data processing module to connect with external devices.

9. The micro-current source system according to claim 8, characterized in that: The output end of the programmable gate array and the input end of the voltage generator, the first input end of the programmable gate array and the output end of the voltage digitization module, and the second input end of the programmable gate array and the output end of the protection module are all connected in an isolated connection manner, wherein the isolated connection manner includes transformer isolation and / or optoelectronic isolator isolation.

10. The micro-current source system according to claim 1, characterized in that: The micro-current source system includes a power supply module, and the power supply module includes a switching power supply module and a DC conversion module; The input end of the switching power supply module is connected to an AC power supply, and the output end is connected to the input end of the DC conversion module; The output end of the DC conversion module is electrically connected to the control module and the current source module; The switching power supply module is used to connect to the AC power supply, convert the input AC power into DC power, and transmit the converted DC power to the DC conversion module; The DC conversion module is used to perform secondary conversion on the DC power to obtain low-noise DC power to power the control module and the current source module.

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