Micro-current detection method based on micro-environment construction

Abstract

The invention relates to a micro-current detection method based on micro-environment construction, and belongs to the field of micro-signal detection. According to the method, an I-V conversion method is adopted as a basic method, a protection ring technology and a microenvironment construction technology are combined, and finally high-precision detection of the micro current is achieved. According to the I-V conversion method, a to-be-measured micro current signal is converted and amplified into a voltage signal with a large amplitude, and the converted voltage signal is measured so as to obtain the size of the to-be-measured micro current signal. When a small current signal is converted and amplified, a low-value resistor network is adopted to replace a high-value resistor as a feedback element. An I-V conversion method is adopted to measure pA and fA level current, a protection ring technology is adopted to form an equipotential area so as to effectively prevent current leakage, a microenvironment construction technology is adopted to put a key circuit into a sealing box, and a drying agent and a temperature and humidity sensor are arranged in the sealing box, so that noise and external interference influence are reduced, and the micro current detection level is improved.

Description

Technical Field

[0001] The present invention belongs to the field of tiny signal detection, and in particular relates to a tiny current detection method based on a microenvironment. Background Art

[0002] With the development of science and technology, a large number of DC microcurrent signals requiring detection are found in my country's aerospace, nuclear industry, instrumentation, and other fields, as well as in scientific research and teaching experiments. These instruments are particularly important in nuclear radiation detection, leakage current measurement, optoelectronic material research, insulation material performance evaluation, semiconductor R&D and production, vacuum measurement, and high-end instrument development. Microcurrent signals, especially those in the picoamp and femtoamp ranges, are not only extremely small in amplitude but also highly susceptible to noise and external interference, making their measurement challenging.

[0003] The basic principles for measuring microcurrents are relatively clear, primarily including the dynamic capacitance method, the Thomson method, the feedback integration method, and the IV conversion method. However, due to the influence of various environmental factors and materials during the actual measurement process, measurement accuracy is relatively low, and the performance indicators of existing domestic products are significantly different from those of foreign products. Summary of the Invention

[0004] The purpose of the present invention is to reduce the influence of noise and external interference and improve the level of tiny current detection. Therefore, a tiny current detection method based on microenvironment construction is provided. The method adopts the IV conversion method as the basic method for tiny current measurement, adopts guard ring technology and microenvironment construction technology, and ultimately achieves the purpose of improving measurement accuracy.

[0005] To achieve the above objectives, the technical solution of the present invention is: a method for detecting tiny currents based on microenvironment construction, which adopts the IV conversion method as the basic method, and combines the guard ring technology and the microenvironment construction technology to ultimately achieve high-precision detection of tiny currents.

[0006] Furthermore, the IV conversion method converts and amplifies the tiny current signal to be measured into a voltage signal with a larger amplitude, and measures the converted voltage signal to obtain the magnitude of the tiny current signal to be measured.

[0007] Furthermore, when converting and amplifying small current signals, a low-value resistor network is used instead of a high-value resistor as a feedback element.

[0008] Furthermore, low-value resistor networks need to be tested and screened based on temperature coefficient parameters.

[0009] Furthermore, a guard ring is a structure used on the surface of a PCB to implement protection technology. The guard ring technology forms electrical contact with all leakage current paths on the PCB surface, surrounds the input path and all sensitive feedback devices with a guard ring, and is driven by a protection voltage to form an equipotential area to effectively prevent leakage current and interrupt capacitive coupling.

[0010] Furthermore, the microenvironment construction technology is to place the key circuit constructed by the IV transformation method into a sealed box.

[0011] Furthermore, a drying device and a temperature and humidity sensor are placed in the sealed box, and the temperature and humidity data collected by the temperature and humidity sensor are used for data correction.

[0012] Furthermore, the drying device includes a desiccant.

[0013] Furthermore, a PCB circuit board integrating key circuits constructed by the IV conversion method is set in the sealed box. A drying device fixing point and a temperature and humidity sensor fixing point are also set in the sealed box. Several openings are also opened on the wall of the sealed box to facilitate the access of small currents and the transmission of signals after IV conversion, and each opening is provided with a sealed connector.

[0014] Furthermore, micro current refers to pA and fA level current.

[0015] Compared with the existing technology, the present invention has the following beneficial effects: the present invention adopts the IV conversion method to measure pA and fA level currents, adopts the guard ring technology to form an equipotential area to effectively prevent leakage current, and adopts the micro-environment construction technology to place the key circuit in a sealed box. The sealed box contains a desiccant and a temperature and humidity sensor to reduce the influence of noise and external interference and improve the level of small current detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The microenvironment constructed for the present invention.

[0017] Figure 2 Schematic diagram of the principle of IV transformation method.

[0018] Figure 3 Schematic diagram of the guard ring technology.

[0019] In the figure: 1, 2, 3 are sealed connectors, 4 is the small current input terminal, and 5 is the fixing point of the drying device. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] The present invention provides a tiny current detection method based on microenvironment construction, which adopts the IV conversion method as the basic method, and combines the guard ring technology and the microenvironment construction technology to ultimately achieve high-precision detection of tiny currents (pA, fA level currents).

[0022] 1. Use IV conversion method to measure small current

[0023] The IV conversion method is used to measure tiny currents. This method converts and amplifies the tiny current signal to be measured into a voltage signal with a larger amplitude. The converted voltage signal is then measured to obtain the magnitude of the tiny current signal to be measured. Since a resistor is required as a feedback element when converting and amplifying the tiny current signal, high-value resistors are typically used. However, high-value resistors are inferior to low-value resistors in terms of long-term stability and temperature coefficient, and high-value resistors reduce the measurement bandwidth. Therefore, the present invention uses a low-value resistor network instead of a high-value resistor, specifically testing and screening the resistor network based on the temperature coefficient parameter.

[0024] The specific principle of IV transformation method is as follows Figure 2 shown.

[0025] A high-value feedback resistor R f It is connected between the output and inverting input of the transimpedance amplifier to form a negative feedback loop. s is injected into the inverting input of the operational amplifier and passes through the feedback resistor R f A voltage drop is generated, which is proportional to the input current. As shown in the following formula:

[0026] V o =-I s *R f

[0027] The present invention adopts a low-value resistor network to replace the high-resistance R f .

[0028] 2. Guard Ring Technology

[0029] Guard technology is fundamental to high-impedance operation. Guard rings are typically used on the PCB surface to implement this protection technology. Solder mask should be removed from high-impedance traces and guard traces to ensure that the guard ring establishes electrical contact with all surface leakage current paths. The guard ring should surround the input path and all sensitive feedback components and be driven by a guard voltage to create an equipotential area, effectively preventing leakage current and interrupting capacitive coupling.

[0030] like Figure 3Figure 2 shows a schematic diagram of guard ring technology. Since PCB leakage current is on the same order of magnitude as the tiny current to be measured, it's crucial to minimize this leakage current during PCB design. To address this, a guard ring structure is designed to reduce measurement errors. This structure uses a grounded guard ring to surround the high-impedance nodes of the amplifier circuit. By aligning the high-impedance nodes with the guard ring, the voltage difference across the insulation resistance is reduced, thereby minimizing leakage current.

[0031] 3. Microenvironment construction technology

[0032] The insulation of PCB is usually around 1000G ohms. Air is the best insulating material, but air is easily affected by temperature and humidity, especially humidity. If the humidity in the air is too high, it is easy to form a floor current. The present invention places the key circuit of the tiny current IV in a sealed box. The sealed box is provided with a drying device (including a desiccant) and a temperature and humidity sensor. The subsequent acquisition circuit can also perform data correction according to the temperature and humidity values. A PCB circuit board integrating the key circuit constructed by the IV conversion method is set in the sealed box. The sealed box is also provided with a drying device fixing part 5 and a temperature and humidity sensor fixing part. A number of openings are also opened on the wall of the sealed box to facilitate the access of tiny current (tiny current is input from the tiny current input terminal 4) and the transmission of the signal after IV conversion, wherein each opening is provided with a sealed connector 1, 2, 3.

[0033] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions and effects do not exceed the scope of the technical solution of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for detecting a small current based on a microenvironment, characterized in that: The IV conversion method is used as the basic method, and combined with the guard ring technology and micro-environment construction technology, high-precision detection of tiny currents is finally achieved.

2. A micro-current detection method based on microenvironment construction according to claim 1, characterized in that: The IV conversion method converts and amplifies the tiny current signal to be measured into a voltage signal with a larger amplitude, and measures the converted voltage signal to obtain the size of the tiny current signal to be measured.

3. The method for detecting a small current based on a microenvironment according to claim 2, wherein: When converting and amplifying small current signals, a low-value resistor network is used instead of a high-value resistor as a feedback element.

4. The method for detecting a small current based on a microenvironment according to claim 3, wherein: Low value resistor networks need to be tested and screened based on temperature coefficient parameters.

5. The method for detecting a small current based on a microenvironment according to claim 1, characterized in that: A guard ring is a structure used on the PCB surface to implement protection technology. Guard ring technology establishes electrical contact with all leakage current paths on the PCB surface, surrounds the input path and all sensitive feedback devices with a guard ring, and is driven by a guard voltage to form an equipotential area to effectively prevent leakage current and interrupt capacitive coupling.

6. The method for detecting a small current based on a microenvironment according to claim 1, characterized in that: The microenvironment construction technology is to place the key circuit constructed by the IV transformation method into a sealed box.

7. The method for detecting a small current based on a microenvironment according to claim 6, characterized in that: A drying device and a temperature and humidity sensor are placed in the sealed box. The temperature and humidity data collected by the temperature and humidity sensor are used for data correction.

8. The method for detecting a small current based on a microenvironment according to claim 7, characterized in that: The drying device includes a desiccant.

9. A method for detecting a small current based on a microenvironment according to claim 6 or 7, characterized in that: A PCB circuit board integrating key circuits constructed by the IV conversion method is set in the sealed box. A drying device fixing point and a temperature and humidity sensor fixing point are also set in the sealed box. Several openings are also opened on the wall of the sealed box to facilitate the access of small currents and the transmission of signals after IV conversion. Each opening is equipped with a sealed connector.

10. The method for detecting a small current based on a microenvironment according to claim 1, characterized in that: Micro current refers to current in the pA and fA levels.

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