Weak current acquisition device

Abstract

The invention relates to a weak current acquisition device, belongs to the technical field of weak signal detection, and solves the problems that in the prior art, signal processing frequency is insufficient, a circuit structure is complex and difficult to design and debug, and high sampling rate and sensitivity cannot be considered at the same time. The weak current acquisition device comprises an acquisition module, a primary amplification module, a secondary amplification module and a feedback network, wherein the acquisition module is used for acquiring a weak current signal and sending the weak current signal to the primary amplification module; the primary amplification module is used for primarily amplifying the collected current signal and then sending the current signal to the secondary amplification module; the secondary amplification module further amplifies the current signal and then sends the current signal to the signal processing terminal; the two ends of the feedback network are connected with the input end and the output end of the second-stage amplification module respectively, and the feedback network is used for adjusting the gain of the second-stage amplification module.

Description

Technical Field

[0001] The present invention relates to the technical field of weak signal detection, and in particular, to a weak current acquisition device. Background Art

[0002] With the development of sensors and the continuous improvement of scientific research requirements, the detection of weak current signals has become increasingly important in many fields. The requirements for the accuracy, speed, frequency, etc. of weak current signal detection continue to increase. Most of the research on the processing of weak current signals tends to lower noise and higher sensitivity, but the limitation of insufficient sampling rate on the application fields of weak current detection technology is becoming more and more obvious.

[0003] However, the existing circuit systems for high-speed processing of weak current signals have the disadvantages of low signal processing frequency, overly complex circuit systems that are not easy to manufacture, and low practicality, making it difficult to meet the actual detection requirements. In actual systems such as sensor arrays that require high-speed acquisition and processing of weak current signals, the signals to be detected often have the characteristics of weak signals, large bandwidths, and a large number of signal channels.

[0004] For these requirements, existing weak current amplification circuits such as resistor feedback type and capacitor feedback type circuits have their own limitations and deficiencies. In order to improve the sensitivity of the circuit to detect even weaker current signals, and in order to increase the system bandwidth, a circuit structure with a higher signal processing frequency should be selected. Whether it is a resistor feedback type amplifier circuit or a capacitor feedback type circuit, it should have a very large amplification factor. To meet the requirement of the amplification factor, the resistance value of the feedback resistor of the resistor feedback type amplifier needs to be set very large, but an overly large feedback resistor will have a significant impact on the stability and bandwidth of the circuit system due to the parasitic capacitance of the circuit board, and the high-frequency characteristics will be greatly limited. The output of the integration amplifier circuit is an integration function related to time and cannot process signals at high frequencies. In addition, in order to meet the requirements of the circuit volume in actual applications, the target amplifier circuit system often needs to use a channel selector, an analog switch device, for channel multiplexing to reduce the number of redundant amplifier circuits and thus reduce the complexity of the circuit. The use of the channel selector introduces the influence of factors such as leakage current into the amplifier circuit, and these influencing factors will cause the amplifier circuit to generate excessive fluctuations, making the circuit system more unstable. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a weak current acquisition device to solve the problems of insufficient signal processing frequency, complex circuit structure that is difficult to design and debug, and the inability to balance high sampling rate and sensitivity in the prior art.

[0006] The embodiments of the present invention provide a weak current acquisition device, including an acquisition module, a first-stage amplification module, a second-stage amplification module, and a feedback network; wherein,

[0007] The acquisition module is used to acquire weak current signals and send them to the first-stage amplification module;

[0008] The first-stage amplification module preliminarily amplifies the acquired current signals and then sends them to the second-stage amplification module;

[0009] The second-stage amplification module further amplifies the current signals and then sends them to the signal processing terminal;

[0010] Both ends of the feedback network are respectively connected to the input end and the output end of the second-stage amplification module, and are used to adjust the gain of the second-stage amplification module.

[0011] As a further improvement of the present application, the second-stage amplification module includes an operational amplifier and a limiter connected in series; one end of the feedback network is connected to the inverting input end of the operational amplifier, and the other end of the feedback network is connected to the output end of the limiter.

[0012] As a further improvement of the present application, the feedback network includes a first feedback resistor, a second feedback resistor, a main feedback resistor, and a feedback capacitor; wherein,

[0013] The feedback capacitor and the main feedback resistor are connected in parallel. A connection point of the feedback capacitor and the main feedback resistor serves as one end of the feedback network and is connected to the inverting input end of the operational amplifier. One end of the first feedback resistor is connected to the other connection point of the feedback capacitor and the main feedback resistor, and the other end is connected to the bias voltage source; one end of the second feedback resistor is connected to the other connection point of the feedback capacitor and the main feedback resistor, and the other end is connected to the output end of the limiter and serves as the other end of the feedback network.

[0014] As a further improvement of the present application, the second-stage amplification module further includes a differential unit. The input end of the differential unit is connected to the output end of the first-stage amplification module and is used to perform differential processing on the output of the first-stage amplification module. The non-inverting input end of the operational amplifier is connected to the bias voltage source, the inverting input end is connected to the output end of the differential unit and one end of the feedback network, and the output end is connected to the input end of the limiter.

[0015] As a further improvement of the present application, the first-stage amplification module includes: an operational amplifier and an integrating capacitor unit; wherein, one end of the integrating capacitor unit is connected to the inverting input end of the operational amplifier, and the other end is connected to the output end of the operational amplifier;

[0016] The non-inverting input end of the operational amplifier is connected to the bias voltage source, the inverting input end is connected to the output end of the acquisition module, and the output end is connected to the input end of the differential unit; the differential unit performs differential processing on the voltage output by the operational amplifier, and the output end of the differential unit serves as the output end of the first-stage amplification module and is connected to the input end of the second-stage amplification module.

[0017] As a further improvement of the present application, the differential unit is a differential capacitor; the integral capacitor unit includes a parallel-connected bias resistor, an integral capacitor, and a switch; when the switch is off, the integral capacitor forms an integral circuit with the inverting input terminal and the output terminal of the operational amplifier to perform integral processing on the weak current signal input by the acquisition module, convert the current signal into a voltage signal, and achieve preliminary amplification of the signal; when the switch is on, the integral capacitor discharges and the circuit enters the reset stage.

[0018] As a further improvement of the present application, the output voltage of the weak current acquisition device is shown in calculation formula (1):

[0019]

[0020] Among them, V out is the output voltage of the weak current acquisition device; C d is the differential capacitor; C f is the integral capacitor; R 1 is the first feedback resistor; R 2 is the second feedback resistor; R d is the main feedback resistor; V Bias is the bias voltage; I in is the current value input by the acquisition module.

[0021] As a further improvement of the present application, the voltage output by the operational amplifier of the first-stage amplification module is shown in calculation formula (2):

[0022]

[0023] Among them, V out1 is the voltage output by the operational amplifier of the first-stage amplification module.

[0024] As a further improvement of the present application, the differential processing of the voltage output by the operational amplifier is shown in calculation formula (3);

[0025]

[0026] Among them, I in2 is the output current of the first-stage amplification module.

[0027] As a further improvement of the present application, the voltage output by the second-stage amplification module is shown in calculation formula (4);

[0028]

[0029] Among them, V out2 is the voltage output by the second-stage amplification module.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] 1. The weak current acquisition device of the present invention can effectively adjust the gain of the secondary amplification module by setting a feedback network in the secondary amplification module, including a first feedback resistor, a second feedback resistor, a main feedback resistor, and a feedback capacitor. Thereby, it improves the frequency of the entire device for processing weak current signals, enabling it to meet the requirements of a high sampling rate detection system, enhancing its practicality in actual applications, and can be widely applied to weak current signal detection scenarios with high frequency requirements.

[0032] 2. The circuit structure of the weak current acquisition device of the present invention reduces the complexity of the circuit by setting an integration unit in the primary amplification module. The integration unit consists of a parallel bias resistor, an integration capacitor, and a switch, and a differential unit is provided with a differential capacitor. Additionally, a differential unit, an operational amplifier, and a limiter are set in the secondary amplification module. This makes the circuit design and debugging more convenient. At the same time, the setting of the feedback network increases the flexibility of the circuit system, enabling it to better adapt to different application requirements and improving the feasibility and stability in actual applications.

[0033] 3. Using the limiter in the secondary amplification module to handle the impact caused by the analog switch can limit the circuit output amplitude and reduce the adverse effects introduced by the analog switch. At the same time, the T-type feedback network composed of the first feedback resistor, the second feedback resistor, and the main feedback resistor makes the bandwidth setting more flexible, improves the bandwidth and signal-to-noise ratio of the capacitive feedback amplifier circuit system. While improving the high-frequency characteristics of the device, it also enhances the sensitivity, enabling it to more accurately detect weak current signals, effectively reducing the system equivalent input noise, and improving the detection accuracy.

[0034] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification. Moreover, some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings are only for the purpose of showing specific embodiments and are not considered as limitations to the present invention. Throughout the drawings, the same reference signs represent the same components;

[0036] Figure 1 is a schematic structural diagram of the weak current acquisition device provided by an embodiment of the present invention;

[0037] Figure 2 is a schematic structural diagram of the weak current acquisition device without a feedback network;

[0038] Figure 3This is a comparison diagram of the effects of the present invention and a weak current acquisition device without a feedback network. Detailed implementation manners

[0039] The following will specifically describe the preferred embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0040] A specific embodiment of the present invention discloses a weak current acquisition device, as Figure 1 shown. A weak current acquisition device includes: an acquisition module, a first-stage amplification module, a second-stage amplification module, and a feedback network; wherein,

[0041] The acquisition module is used to acquire weak current signals and send them to the first-stage amplification module;

[0042] The first-stage amplification module preliminarily amplifies the acquired current signal and then sends it to the second-stage amplification module;

[0043] The second-stage amplification module further amplifies the current signal and then sends it to the signal processing terminal;

[0044] Both ends of the feedback network are respectively connected to the input end and the output end of the second-stage amplification module, and are used to adjust the gain of the second-stage amplification module.

[0045] It should be noted that weak current refers to an electrical signal with a very small amplitude, and its amplitude is usually less than 10 -6 A. Weak current signals not only have a weak intensity themselves, but also are often accompanied by a strong noise background in the actual detection environment.

[0046] The acquisition module is used to acquire weak current signals, convert the corresponding physical quantity into a weak current signal through a sensor and collect it, and send it to the first-stage amplification module. The sensor can include a photoelectric sensor, a thermocouple sensor, a strain gauge sensor, etc.

[0047] Furthermore, the second-stage amplification module includes an operational amplifier and a limiter connected in series; one end of the feedback network is connected to the inverting input end of the operational amplifier, and the other end of the feedback network is connected to the output end of the limiter.

[0048] The operational amplifier of the second-stage amplification module further amplifies the input signal, and its amplification multiple can be determined according to the feedback network and its own gain characteristics. The limiter performs a limiting process on the output signal of the operational amplifier to prevent an excessive signal amplitude from causing adverse effects on the subsequent circuit.

[0049] The feedback network includes a first feedback resistor R 1 , a second feedback resistor R 2 , a main feedback resistor R dand feedback capacitor C c ; wherein, the feedback capacitor C c is in parallel with the main feedback resistor R d ; one connection point of the feedback capacitor C c and the main feedback resistor R d serves as one end of the feedback network and is connected to the inverting input terminal of the operational amplifier. One end of the first feedback resistor R 1 is connected to the other connection point of the feedback capacitor C c and the main feedback resistor R d , and the other end is connected to the bias voltage source; one end of the second feedback resistor R 2 is connected to the other connection point of the feedback capacitor C c and the main feedback resistor R d , and the other end is connected to the output terminal of the limiter R 3 and serves as the other end of the feedback network.

[0050] The value selection of the main feedback resistor R d needs to be set by comprehensively considering the gain required by the two-stage amplification module, the stability of the circuit, and the signal amplitude range, and can be selected according to the actual amplification effect and system performance during the debugging process. The value of the first feedback resistor R1 is determined by the design requirements of the feedback network, and the ratio of the second feedback resistor R2 to the first feedback resistor R1 determines the gain of the second-stage amplification module. The use of the T-shaped network allows for more flexible setting of the system bandwidth while increasing the gain of the differential amplifier, without relying too much on the parameter selection of the feedback capacitor Cc and the main feedback resistor Rd. This design method relaxes the requirements for Cc and Rd, making the adjustment of the bandwidth more flexible. The feedback capacitor C c is in parallel with the main feedback resistor R d and is used to adjust the frequency response characteristics of the feedback network. The selection of the capacitance value will affect the high-frequency gain and cut-off frequency of the circuit. When a wide frequency band is required, a smaller capacitance value can be selected; when a narrow frequency band is required, a larger capacitance value can be selected.

[0051] The feedback capacitor C c is in parallel with the main feedback resistor R d ; one connection point of the feedback capacitor C c and the main feedback resistor R d serves as one end of the feedback network and is connected to the inverting input terminal of the operational amplifier in the two-stage amplification module, so that the output signal of the operational amplifier is fed back to its inverting input terminal through the feedback network to achieve negative feedback, which can stabilize the gain of the circuit and reduce distortion.

[0052] One end of the first feedback resistor R 1 is connected to the feedback capacitor C c in parallel with the main feedback resistor R dAnother connection point, with the other end connected to a bias voltage source, and the bias voltage source is connected to the first feedback resistor R 1 provides a DC bias for the feedback network, ensuring that the inverting input terminal of the operational amplifier is at an appropriate DC potential, enabling it to operate in the normal linear amplification region.

[0053] Furthermore, the second-stage amplification module further includes a differentiation unit. The input terminal of the differentiation unit is connected to the output terminal of the first-stage amplification module for differentiating the output of the first-stage amplification module. The non-inverting input terminal of the operational amplifier is connected to the bias voltage source, the inverting input terminal is connected to the output terminal of the differentiation unit and one end of the feedback network, and the output terminal is connected to the input terminal of the limiter.

[0054] An operational amplifier is an amplifier with high gain, high input impedance, and low output impedance, which can be used for various analog signal processing operations such as amplification, filtering, and comparison. To make the operational amplifier operate in its linear region, the non-inverting input terminal of the operational amplifier needs to be connected to a suitable bias voltage source, and a voltage regulator chip can be used as the bias voltage source. The inverting input terminal of the operational amplifier is connected to the output terminal of the first-stage amplification module to receive the weak current signal after being amplified and processed by the first stage. The inverting input terminal of the operational amplifier is also connected to one end of the feedback network, that is, the feedback capacitor C c and the main feedback resistor R d at a connection point, and the gain and frequency response of the operational amplifier are controlled by the adjustment of the feedback network. The output terminal of the operational amplifier is connected to the input terminal of the limiter to transmit the amplified signal to the limiter R 3 . The limiter R 3 is used to limit the amplitude of the output of the circuit, and can limit the excessive amplitude caused during the operation of the analog switch while ensuring the normal amplification of the current signal.

[0055] The differentiation unit differentiates the weak current signal that has been integrated and output by the first-stage amplification module. The differentiation process separates the fast-changing information of the signal from the integrated signal, further extracts the rate-of-change information of the signal, and transmits it to the second-stage amplification module.

[0056] The voltage output by the second-stage amplification module is as shown in Equation (1);

[0057]

[0058] where, V out2 is the voltage output by the second-stage amplification module.

[0059] R 1 is the first feedback resistor; R 2 is the second feedback resistor; R d is the main feedback resistor; V Biasis the bias voltage; I in2 is the output current of the first-stage amplification module.

[0060] Further, the first-stage amplification module includes: an operational amplifier and an integration capacitor unit; wherein, one end of the integration capacitor unit is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier;

[0061] The non-inverting input terminal of the operational amplifier is connected to the bias voltage source, the inverting input terminal is connected to the output terminal of the acquisition module, and the output terminal is connected to the input terminal of the differential unit; the differential unit performs differential processing on the voltage output by the operational amplifier, and the output terminal of the differential unit is used as the input terminal of the second-stage amplification module and is connected to the output terminal of the first-stage amplification module.

[0062] The operational amplifier receives the weak current signal output by the acquisition module and performs amplification processing, and the integration capacitor unit performs integration processing on the weak current signal. The input weak current signal is accumulated in time, which can suppress the noise of the weak current signal and convert the current signal into a voltage signal.

[0063] Specifically, the differential unit is the differential capacitor C d ; the integration capacitor unit includes a parallel-connected bias resistor R bias , integration capacitor C f and switch R est ; when the switch R est is disconnected, an integration network is formed, and the integration capacitor C f forms an integration circuit with the inverting input terminal and the output terminal of the operational amplifier to perform integration processing on the weak current signal input by the acquisition module; when the switch R est is closed, the integration capacitor C f discharges, and the circuit enters the reset stage. At this time, the integration circuit does not participate in the amplification of the weak current signal. The size of the integration capacitor C f determines the time constant of the integration, and its selection depends on the required integration effect and the signal frequency range. When the switch R est is closed, the integration circuit starts to work, and the weak current signal input to the operational amplifier passes through the integration capacitor C fIntegrate to form a voltage signal. The integration process accumulates the weak current signal over time and converts it into a voltage signal. The size of the integration capacitor determines the time constant of the integration, and its selection depends on the required integration effect and the signal frequency range. When the switch is closed, the integration circuit starts to work. The weak current signal input to the operational amplifier is integrated through the integration capacitor to form a voltage signal. The integration process accumulates the weak current signal over time and converts it into a voltage signal. To prevent the integration capacitor from being easily saturated due to its small capacitance value and losing its integration function, it needs to be discharged regularly. Therefore, when the integration capacitor reaches a certain voltage level or after a specific time interval, the integration is stopped and the capacitor is discharged by opening the closed switch to ensure that the integration capacitor can continue to perform effective integration operations. In a periodic signal acquisition system, the switch can be closed at the beginning of each period for integration, and the switch is opened at the end of the period to save the integration result.

[0064] The voltage output by the operational amplifier of the first-stage amplification module is as shown in Equation (2):

[0065]

[0066] Among them, V out1 is the voltage output by the operational amplifier of the first-stage amplification module, I in is the current value input by the acquisition module, and C f is the integration capacitor.

[0067] One end of the differential capacitor C d is connected to the output end of the operational amplifier, and the other end is connected to the input end of the second-stage amplification module. The differential capacitor C d performs differential processing on the voltage signal after integration output by the operational amplifier to extract the rate-of-change information of the signal.

[0068] The differential processing of the voltage output by the operational amplifier is as shown in Equation (3);

[0069]

[0070] Among them, I in2 is the output current of the first-stage amplification module, and C d is the differential capacitor.

[0071] The output voltage of the weak current acquisition device is as shown in Equation (4):

[0072]

[0073] Among them, V out is the output voltage of the weak current acquisition device; C d is the differential capacitor; C f is the integration capacitor; R1 is the first feedback resistor; R 2 is the second feedback resistor; R d is the main feedback resistor; V Bias is the bias voltage; I in is the current value input by the acquisition module.

[0074] The above embodiments of the present invention have at least the following beneficial effects:

[0075] The weak current acquisition device of the present invention effectively limits the excessive current pulses generated during the discharge of the integration capacitor caused by factors such as the leakage current of the analog switch by setting a limiting circuit composed of R3 in the secondary amplification module, which helps to accelerate the circuit system's departure from the influence of the capacitor discharge stage, thereby extending the proportion of the stable amplification stage of the input weak current in each cycle of the circuit, and improving the stability and accuracy of the signal. By introducing a T-shaped network composed of Rd, R1, and R2 in the secondary amplification module, more flexible bandwidth and gain adjustment are provided. Before R1 and R2 were introduced in the prior art, the amplification factor of the second stage was almost entirely determined by Rd, and the increase of Rd would increase the amplification factor of the second stage. At the same time, Rd and Cc jointly determined the bandwidth of the second stage. In this application, by setting the T-shaped network, the amplification factor of the second stage is controlled by the resistance ratio of R1 and R2, reducing the requirements for Rd, making the bandwidth of the second stage amplification easier to control, and thus improving the flexibility and adaptability of the circuit. The weak current acquisition device of the present invention reduces the complexity of the circuit by setting an integration unit and a differentiation unit in the primary amplification module and the secondary amplification module. The integration unit consists of a parallel bias resistor, an integration capacitor, and a control switch Rest, and the differentiation unit is provided with a differentiation capacitor, making the circuit design and debugging more convenient. The feedback network includes a first feedback resistor, a second feedback resistor, a main feedback resistor, and a feedback capacitor, increasing the flexibility of the circuit system, enabling it to better adapt to different application requirements, and improving the feasibility and stability in practical applications.

[0076] To further verify the present invention, Figure 2 shows a weak current acquisition device without a feedback network in the prior art. As Figure 3As shown. The weak current acquisition device without a feedback network is sensitive to changes in the input signal. When processing weak current signals, it cannot effectively suppress noise and interference. The gain of the circuit is unstable and is easily affected by changes in component parameters and external interference. There are obvious fluctuations in the waveform of the voltage output value. There are obvious fluctuations in the waveform of the voltage output value, especially at the marked nodes, and there are peaks and valleys with excessive amplitude fluctuations in the waveform diagram, indicating that the existing technology lacks anti-interference ability and cannot maintain the original characteristics of weak current signals, resulting in signal distortion during the acquisition process, thereby affecting the utilization efficiency of the entire system for weak current signals. The waveform of the present application can maintain a relatively regular and smooth output, with uniform changes in shape and amplitude, ensuring the quality and analyzability of the signal and reducing signal distortion.

[0077] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A weak current collection device, characterized in that: include: Acquisition module, primary amplification module, secondary amplification module and feedback network; wherein, The acquisition module is used to collect weak current signals and send them to the first-stage amplification module; The first-stage amplification module preliminarily amplifies the collected current signal and sends it to the second-stage amplification module; The secondary amplification module further amplifies the current signal and sends it to the signal processing terminal; The two ends of the feedback network are respectively connected to the input end and the output end of the secondary amplification module, and are used to adjust the gain of the secondary amplification module.

2. The device according to claim 1, characterized in that The secondary amplification module comprises an operational amplifier and a limiter connected in series; one end of the feedback network is connected to the inverting input end of the operational amplifier, and the other end of the feedback network is connected to the output end of the limiter.

3. The device according to claim 2, characterized in that The feedback network includes a first feedback resistor, a second feedback resistor, a main feedback resistor and a feedback capacitor; wherein, The feedback capacitor and the main feedback resistor are connected in parallel, a connection point between the feedback capacitor and the main feedback resistor serves as one end of the feedback network and is connected to the inverting input terminal of the operational amplifier, one end of the first feedback resistor is connected to another connection point between the feedback capacitor and the main feedback resistor, and the other end is connected to the bias voltage source; one end of the second feedback resistor is connected to another connection point between the feedback capacitor and the main feedback resistor, and the other end is connected to the output terminal of the limiter and serves as the other end of the feedback network.

4. The device according to claim 3, characterized in that The secondary amplification module also includes a differential unit, the input end of the differential unit is connected to the output end of the primary amplification module, and is used to perform differential processing on the output of the primary amplification module. The non-phase input end of the operational amplifier is connected to the bias voltage source, the inverting input end is connected to the output end of the differential unit and one end of the feedback network, and the output end is connected to the input end of the limiter.

5. The device according to claim 4, characterized in that The first-stage amplification module includes: an operational amplifier and an integral capacitor unit; wherein one end of the integral capacitor unit is connected to the inverting input end of the operational amplifier, and the other end is connected to the output end of the operational amplifier; The non-inverting input terminal of the operational amplifier is connected to the bias voltage source, the inverting input terminal is connected to the output terminal of the acquisition module, and the output terminal is connected to the input terminal of the differential unit; the differential unit performs differential processing on the voltage output by the operational amplifier, and the output terminal of the differential unit is connected to the input terminal of the secondary amplification module as the output terminal of the primary amplification module.

6. The device according to claim 5, characterized in that The integral capacitor unit includes a bias resistor, an integral capacitor and a switch connected in parallel; When the switch is turned off, the integral capacitor and the inverting input and output terminals of the operational amplifier form an integral circuit to integrate the weak current signal input by the acquisition module, convert the current signal into a voltage signal, and achieve preliminary amplification of the signal; When the switch is closed, the integrating capacitor is discharged and the circuit enters the reset phase.

7. The device according to claim 6, characterized in that The output voltage of the weak current acquisition device is shown in formula (1): Among them, V out is the output voltage of the weak current collection device; C d is the differential capacitance; C f is the integrating capacitor; R1 is the first feedback resistor; R2 is the second feedback resistor; R d is the main feedback resistor; V Bias is the bias voltage; I in It is the current value input by the acquisition module.

8. The device according to claim 7, characterized in that The voltage output by the operational amplifier of the first-stage amplification module is shown in formula (2): Among them, V out1 It is the voltage output by the operational amplifier of the first-stage amplification module.

9. The device according to claim 8, characterized in that The differential processing of the voltage output by the operational amplifier is shown in formula (3); Among them, I in2 It is the output current of the first-stage amplifier module.

10. The device according to claim 9, characterized in that The voltage output by the secondary amplification module is shown in formula (4); Among them, V out2 It is the voltage output by the secondary amplifier module.

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