Conductive current measuring device

Abstract

The embodiment of the invention discloses a conductance current measuring device. The conductance current measuring device comprises a voltage supply module, a reference channel, a sample channel and a feedback channel, wherein the sample channel comprises a measured sample; the voltage supply module is connected with the reference channel and the sample channel; the voltage supply module is used for providing linearly rising voltage superposed with sine waves for the reference channel and the sample channel; the reference channel is connected with the feedback channel, the sample channel is connected with the feedback channel, and the sample channel is used for performing conductance current measurement on a measured sample according to the voltage which linearly rises and is superposed with sine waves and outputting a sample channel signal; the reference channel is used for processing the voltage which linearly rises and is superposed with sine waves and outputting a reference channel signal which is approximately matched with the sample channel signal; and the feedback channel is used for processing the reference channel signal and the sample channel signal and enabling the reference channel signal and the sample channel signal to be completely matched. According to the invention, the conductance current of the insulating material in an electric field in a large range can be rapidly measured in real time.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of signal measurement, and in particular, to a conductance current measurement device. Background Art

[0002] When the voltage applied to an insulating material exceeds a certain value, the conductance current flows through the insulating material uncontrollably, resulting in electrical breakdown. Conductance is closely related to the breakdown phenomenon. Studying phenomena such as conductance near the breakdown field strength is of great significance for understanding the breakdown of insulating materials. Accurately measuring the conductance current of insulating materials near the breakdown field strength is the basis.

[0003] The measurement of the conductance current of insulating materials under strong electric fields can only be achieved through transient measurement, and transient measurement will cause the capacitive absorption current to be much larger than the conduction current. Currently, there is no experimental method that can measure the conductance current of insulating materials in a very wide range of electric fields (rising from zero to near the breakdown field strength) in real time and quickly. The widely used method for measuring the conductance current of insulating materials is based on quasi-steady-state current measurement. A required voltage is applied to the sample, and the measurement is carried out when the absorption current is low enough according to the RC time constant. However, the disadvantage of this measurement method is that the thermal breakdown caused by thermal runaway will cause the test sample to break down before reaching the breakdown field strength. Therefore, the applied field strength can only reach about two-thirds of the breakdown field strength. Under such an electric field, electrons are more likely to be transmitted through tunneling or hopping effects rather than entering the conduction band, resulting in a large error in the measurement of the conductance current. Measuring the conductance current of insulating materials directly at high temperatures is another measurement method, but this method is only limited to a few heat-resistant materials. In addition, there is also a test device based on microgeometry. In this method, a needle with a radius of 5 μm is inserted into the sample, and a time-varying voltage is applied between the needle-plate electrodes. Charges that change with time are generated on the tip of the needle. Among them, the charges caused by displacement current are less, and what is measured and determined is the change of non-capacitive charges on the tip of the needle. However, the research on microgeometry in this method is not applicable to insulating materials with a large area.

[0004] In summary, when the existing conductance current measurement device tests a sample, it cannot eliminate the capacitive absorption current in the measurement result, resulting in low accuracy of the conduction current measurement and inability to measure the conductance current of insulating materials in a very wide range of electric fields in real time and quickly. Summary of the Invention

[0005] The present invention provides a conductance current measurement device, which can eliminate the capacitive absorption current in the measurement result, improve the accuracy of the conduction current measurement, and can measure the conductance current of insulating materials in a very wide range of electric fields in real time and quickly.

[0006] According to one aspect of the present invention, a conductance current measuring device is provided. The conductance current measuring device includes: a voltage supply module, a reference channel, a sample channel, and a feedback channel. The sample channel includes a sample to be measured.

[0007] The voltage supply module is connected to the reference channel and the sample channel. The voltage supply module is configured to provide a voltage that linearly increases and is superimposed with a sine wave to the reference channel and the sample channel.

[0008] The reference channel is connected to the feedback channel, and the sample channel is connected to the feedback channel. The sample channel is configured to measure the conductance current of the sample to be measured according to the voltage that linearly increases and is superimposed with a sine wave and output a sample channel signal. The reference channel is configured to process the voltage that linearly increases and is superimposed with a sine wave and output a reference channel signal that approximately matches the sample channel signal. The feedback channel is configured to process the reference channel signal and the sample channel signal and make them exactly match.

[0009] Optionally, the voltage supply module includes: a high-voltage power supply and a voltage divider.

[0010] The high-voltage power supply is connected to the voltage divider. The high-voltage power supply is configured to generate a voltage that linearly increases and is superimposed with a sine wave.

[0011] The voltage divider is connected to the reference channel and the sample channel. The voltage divider is configured to adjust the amplitude of the voltage that linearly increases and is superimposed with a sine wave.

[0012] Optionally, the reference channel includes: a voltage follower and an inverting variable gain amplifier.

[0013] The voltage follower is connected between the voltage supply module and the inverting variable gain amplifier. The voltage follower is configured to keep the voltage input to the inverting variable gain amplifier stable.

[0014] The inverting variable gain amplifier is connected to the feedback channel. The inverting variable gain amplifier is configured to increase the gain of the reference channel signal.

[0015] Optionally, the sample channel further includes: an inverting amplifier.

[0016] The sample to be measured is connected between the voltage supply module and the inverting amplifier. The inverting amplifier is connected to the feedback channel. The inverting amplifier is configured to integrate the resistive current passing through when measuring the conductance current of the sample to be measured, adjust the capacitive current passing through when measuring the conductance current of the sample to be measured, and output a sample channel signal that approximately matches the reference channel signal.

[0017] Optionally, the feedback channel includes: a differential amplifier, a digital lock-in amplifier, and a voltage-controlled amplifier;

[0018] The differential amplifier is connected to the digital lock-in amplifier and the sample channel, and the differential amplifier is configured to differentially amplify the reference channel signal and the sample channel signal and transmit them to the digital lock-in amplifier;

[0019] The digital lock-in amplifier is connected to the voltage-controlled amplifier, and the digital lock-in amplifier is configured to monitor in real time whether the capacitive current components of the reference channel signal and the sample channel signal are completely canceled out, and output a signal with the same frequency as the reference input signal;

[0020] The voltage-controlled amplifier is connected to the differential amplifier and the reference channel, and the voltage-controlled amplifier is configured to receive the output signal from the digital lock-in amplifier and adjust the reference channel signal to match the sample channel signal.

[0021] Optionally, the sample under test includes: a first conductor, a sample, and a second conductor;

[0022] The first conductor is an upper electrode, and the upper electrode is located on the upper surface of the sample;

[0023] The second conductor is a lower electrode, and the lower electrode is located on the lower surface of the sample.

[0024] Optionally, the sample under test further includes a mask, the mask is located between the first conductor and the sample, and the breakdown strength of the mask is greater than the breakdown strength of the sample;

[0025] A blank area is reserved at the center of the mask, and the blank area is used as the measurement area for the conductance current of the sample.

[0026] Optionally, the inverting variable gain amplifier is an operational amplifier, and the models of the operational amplifier include at least one of LM741, AD829, AD823, and AD549.

[0027] Optionally, the inverting amplifier is an operational amplifier, and the models of the operational amplifier include at least one of LM741, AD829, AD823, and AD549.

[0028] Optionally, the model of the differential amplifier includes at least one of INA148, INA132, INA105, INA597, INA157, INA106, and INA116; the model of the digital lock-in amplifier includes at least one of SRS830 and SR865A; the model of the voltage-controlled amplifier includes at least one of VCA820, VCA810, and SSM2018T.

[0029] The technical solution of the embodiment of the present invention provides a conductance current measurement device based on capacitive current cancellation, which can measure the conductance current of insulating materials in a very large range of electric fields in real time and quickly. The measurement device can eliminate the capacitive absorption current in the measurement result, improve the accuracy of the conduction current measurement, and obtain the transient conductance of the insulating material in a very large range of electric fields (rising from zero to near the breakdown field strength) in real time and quickly, which helps to study the characteristics and mechanisms of the insulating material. In summary, the present invention solves the problems that the existing conductance current measurement device cannot eliminate the capacitive absorption current in the measurement result, resulting in low accuracy of the conduction current measurement and inability to measure the conductance current of the insulating material in a very large range of electric fields in real time and quickly.

[0030] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 is a schematic structural diagram of a conductance current measurement device provided according to an embodiment of the present invention;

[0033] Figure 2 is a schematic structural diagram of another conductance current measurement device provided according to an embodiment of the present invention;

[0034] Figure 3 is a schematic structural diagram of a measured sample provided according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] To enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0037] Figure 1 is a schematic structural diagram of a conductance current measurement device provided according to an embodiment of the present invention. Refer to Figure 1 In this regard, an embodiment of the present invention provides a conductance current measurement device, which includes: a voltage supply module 10, a reference channel 20, a sample channel 30, and a feedback channel 40. The sample channel 30 includes a sample under test 31;

[0038] The voltage supply module 10 is connected to the reference channel 20 and the sample channel 30. The voltage supply module 10 is used to provide a voltage with a linearly increasing and superimposed sine wave for the reference channel 20 and the sample channel 30;

[0039] The reference channel 20 is connected to the feedback channel 40, and the sample channel 30 is connected to the feedback channel 40. The sample channel 30 is used to measure the conductance current of the sample under test 31 according to the voltage with a linearly increasing and superimposed sine wave and output a sample channel signal. The reference channel 20 is used to process the voltage with a linearly increasing and superimposed sine wave and output a reference channel signal approximately matching the sample channel signal. The feedback channel 40 is used to process the reference channel signal and the sample channel signal to make them completely match.

[0040] Specifically, in the voltage supply module 10, the voltage required for testing is directly generated by a high-voltage power supply. In this embodiment, a voltage with a linear rise of 250V / s is superimposed with a 5V, 2kHz sine-wave voltage as the voltage provided to the subsequent part. The generated voltage is used as the input of the reference channel 20 after passing through a voltage divider, and is also directly used as the input of the sample channel 30.

[0041] The sample under test 31 can be an insulating material, and a small, high-frequency sine-wave voltage is superimposed on the voltage linearly rising from zero to the breakdown voltage of the insulating material. When only a linearly rising voltage is applied to the material under test, near the breakdown field strength of the material under test, the capacitive current is much larger than the resistive current, and the two cannot be distinguished. The superimposed sine-wave voltage can cancel the capacitive current generated in the circuit. As long as the dielectric constant of the material under test is independent of frequency, the capacitive current generated by the sine-wave voltage can cancel all the capacitive currents in the circuit. This "cancellation" operation is achieved through differential amplification of the two channels.

[0042] The above two channels are the reference channel 20 and the sample channel 30 respectively. The reference channel 20 includes multiple integrated circuit chips to make the reference channel signal approximately match the sample channel signal. The sample channel 30 consists of the sample under test 31 and integrated circuit chips. In addition, the feedback channel 40 is used to make the signals of the above two channels fully match. Through negative feedback, the capacitive component is completely cancelled, and the signal after differential amplification is the required resistive component.

[0043] The purpose of the conductance current measurement device is to eliminate the capacitive current component in the entire circuit system. Therefore, the feedback channel 40 is used to perform differential amplification on the signals from the reference channel 20 and the sample channel 30 respectively. If the capacitive currents in the two signals match each other, the signal output by the feedback channel 40 is the integrated resistive current signal, that is, the current to be measured. However, it is very difficult for the capacitive current components in the above two signals to be matched after the processing of the reference channel 20 and the sample channel 30. Therefore, the feedback channel 40 is required to achieve this purpose.

[0044] The conductance current measurement device in this embodiment is based on the dynamic cancellation of capacitive current, and can measure the conductance of insulating materials in a very wide range of electric fields (rising from zero to near the breakdown field strength) in real time and quickly, paving the way for the basic research on the conductance characteristics, breakdown characteristics, etc. of insulating materials.

[0045] The technical solution of the embodiment of the present invention provides a conductance current measurement device based on capacitive current cancellation, which can measure the conductance current of insulating materials in a very wide range of electric fields in real time and quickly. This measurement device can eliminate the capacitive absorption current in the measurement result, improve the accuracy of conduction current measurement, and obtain the transient conductance of insulating materials in a very wide range of electric fields (rising from zero to near the breakdown field strength) in real time and quickly, which helps to study the characteristics and mechanisms of insulating materials. In summary, the present invention solves the problems that the existing conductance current measurement devices cannot eliminate the capacitive absorption current in the measurement result, resulting in low accuracy of conduction current measurement and inability to measure the conductance current of insulating materials in a very wide range of electric fields in real time and quickly.

[0046] Figure 2 It is a structural schematic diagram of another conductance current measurement device provided according to an embodiment of the present invention. Refer to Figure 2 , optionally, the voltage supply module 10 includes: a high-voltage power supply 11 and a voltage divider 12;

[0047] The high-voltage power supply 11 is connected to the voltage divider 12, and the high-voltage power supply 11 is used to generate a voltage that linearly rises and superimposes a sine wave;

[0048] The voltage divider 12 is connected to the reference channel 20 and the sample channel 30, and the voltage divider 12 is used to adjust the amplitude of the voltage that linearly rises and superimposes a sine wave.

[0049] Specifically, a small, high-frequency sine wave voltage is superimposed on the linearly rising ramp voltage, where the linearly rising ramp voltage is used to make the field strength reach the breakdown field strength of the insulating material, and the sine wave voltage is used to generate a signal that cancels all capacitive currents in the circuit. The generation method of this voltage includes: directly generated by a programmable high-voltage power supply; the ramp voltage and the sine wave voltage are respectively output by two power supplies, and the sine wave is superimposed on the ramp voltage through a high-voltage capacitor, etc.; generated by multiple power supplies or devices and superimposed together, etc.

[0050] The voltage divider 12 is used to adjust the amplitude of the voltage generated by the high-voltage power supply 11 to be within the safe operating range of the integrated circuit chip. The voltage divider 11 includes specific circuits such as a common resistor voltage divider circuit, and also includes voltage dividing devices such as high-voltage probes that directly have a certain voltage division ratio. The voltage divider 12 is also used for voltage reduction, so that the input voltage of the operational amplifier, etc. entering the reference channel 20 and the sample channel 30 in the subsequent link is within the power supply voltage range to protect each integrated circuit chip.

[0051] Continue to refer to Figure 2 , optionally, the reference channel 20 includes: a voltage follower 21 and an inverting variable gain amplifier 22;

[0052] The voltage follower 21 is connected between the voltage supply module 10 and the inverting variable gain amplifier 22, and the voltage follower is used to keep the voltage input to the inverting variable gain amplifier stable;

[0053] The inverting variable gain amplifier 22 is connected to the feedback channel 40, and the inverting variable gain amplifier 22 is used to increase the gain of the reference channel signal.

[0054] Specifically, the reference channel 20 includes a multi-stage voltage follower 21 composed of operational amplifiers and an inverting variable gain amplifier 22, which is used to achieve an approximate match between the reference channel signal and the sample channel signal. The voltage follower 21, as the pre-stage of the inverting variable gain amplifier 22, plays a role in buffering the voltage, so that the input voltage remains stable when the gain of the inverting variable gain amplifier 22 changes. The voltage follower 21 can be implemented by an operational amplifier, and the number can be one or more, which is determined according to actual needs.

[0055] Continue to refer to Figure 2 Optionally, the sample channel 30 further includes: an inverting amplifier 32;

[0056] The measured sample 31 is connected between the voltage supply module 10 and the inverting amplifier 32, and the inverting amplifier 32 is connected to the feedback channel 40. The inverting amplifier 32 is used to integrate the resistive current passing through when measuring the conductance current of the measured sample 31, adjust the capacitive current passing through when measuring the conductance current of the measured sample 31, and output a sample channel signal approximately matching the reference channel signal.

[0057] Specifically, the sample channel 30 directly uses the voltage generated by the high-voltage power supply 11 as the input, and this voltage is applied between the high-voltage electrode and the ground electrode of the measured sample 31. The ground electrode of the measured sample 31 is connected to the input end of the inverting amplifier 32, and the feedback of the inverting amplifier 32 is a capacitor, and the inverting gain is much less than 1. For the resistive current passing through the measured sample 31, the inverting amplifier 32 acts as an integrator; for the capacitive current passing through the measured sample 31, the inverting amplifier 32 causes it to have a 180° phase shift and an appropriate proportion of adjustment to make it approximately match the reference channel signal. When the measured sample 31 is broken down, the input of the inverting amplifier 32 will be affected transiently, and it is necessary to use a gas discharge tube, etc. to protect the integrated circuit chip.

[0058] Continue to refer to Figure 2 Optionally, the feedback channel 40 includes: a differential amplifier 41, a digital lock-in amplifier 42, and a voltage-controlled amplifier 43;

[0059] The differential amplifier 41 is connected to the digital lock-in amplifier 42 and the sample channel 30. The differential amplifier 41 is used to differentially amplify the reference channel signal and the sample channel signal and transmit them to the digital lock-in amplifier 42;

[0060] The digital lock-in amplifier 42 is connected to the voltage-controlled amplifier 43. The digital lock-in amplifier 42 is used to monitor in real time whether the capacitive current components of the reference channel signal and the sample channel signal are completely canceled out, and output a signal with the same frequency as the reference input signal;

[0061] The voltage-controlled amplifier 43 is connected to the differential amplifier 41 and the reference channel 20. The voltage-controlled amplifier 43 is used to receive the output signal from the digital lock-in amplifier 42 and adjust the reference channel signal to match the sample channel signal.

[0062] Specifically, the purpose of the conductance current measurement device is to eliminate the capacitive current component in the entire circuit system. Therefore, the differential amplifier 41 is used to differentially amplify the signals from the reference channel and the sample channel. If the capacitive currents in the two signals match each other, the signal output by the differential amplifier 41 is the integrated resistive current signal, that is, the current to be measured. However, it is very difficult for the capacitive current components in the above two signals to complete the matching after the processing of the reference channel 20 and the sample channel 30. Therefore, the feedback channel 40 is needed to achieve this purpose.

[0063] In addition to the differential amplifier 41, the feedback channel 40 also includes a digital lock-in amplifier 42 and a voltage-controlled amplifier 43. The filter in the feedback channel 40 is used to eliminate the high-frequency components caused by discharge before the measured sample 31 breaks down. Without the filter, it will cause the input of the digital lock-in amplifier 42 to be overloaded. The digital lock-in amplifier 42 is used to monitor in real time whether the capacitive current components in the entire circuit are completely canceled out. The input of the digital lock-in amplifier 42 is the signal after filtering the output signal of the differential amplifier 41, and its reference input is a small, high-frequency sine signal superimposed on a linearly rising voltage, that is, the 10V, 1kHz sine signal in this embodiment. The digital lock-in amplifier 42 can output the amplitude of the signal with the same frequency as the reference input signal. This output signal is processed and used as the control signal of the voltage-controlled amplifier 43, so that the output signal of the reference channel 20 obtains a certain gain, and thus can better match the sample channel signal. The entire feedback channel 40 can automatically cancel the capacitive current components in the entire circuit through negative feedback. If the cancellation is completed, there will be no capacitive component at the output end of the differential amplifier 41, and the output of the digital lock-in amplifier 42 also becomes 0, indicating that the negative feedback has reached stability. At this time, the signal output by the differential amplifier 41 is the integral value to be measured. Further calculations with the applied voltage are used to obtain the conductance of the measured sample 31.

[0064] Figure 3It is a schematic structural diagram of a sample to be measured according to an embodiment of the present invention. Refer to Figure 3 , optionally, the sample 31 to be measured includes: a first conductor 311, a sample 312, and a second conductor 313;

[0065] The first conductor 311 is an upper electrode, and the upper electrode is located on the upper surface of the sample 312;

[0066] The second conductor 313 is a lower electrode, and the lower electrode is located on the lower surface of the sample 312.

[0067] Specifically, the structure of the sample 31 to be measured includes a first conductor 311, a sample 312, and a second conductor 313. The conductor includes conductive rubber, plated electrodes, metallized films, etc. Among them, the first conductor 311 and the second conductor 313 serve as the high-voltage electrode and the ground electrode of the sample 312, respectively.

[0068] Using conductive rubber as the conductor, it is placed on the upper and lower surfaces of the sample 312 respectively to act as the upper electrode and the lower electrode. The upper electrode is the high-voltage electrode of the sample 312, and the voltage generated by the high-voltage power supply is directly supplied to this electrode; the lower electrode is the ground electrode of the sample 312, and this electrode is connected to the input of the inverting amplifier. When measuring, the upper and lower electrodes can be used to select the test area of the sample, but it is necessary to ensure that the upper and lower electrodes completely coincide and there is good contact between the electrodes and the sample 312.

[0069] Continue to refer to Figure 3 , optionally, the sample 31 to be measured further includes a mask 314, the mask 314 is located between the first conductor 311 and the sample 312, and the breakdown strength of the mask 314 is greater than the breakdown strength of the sample 312;

[0070] A blank area 315 is reserved in the center of the mask 314, and the blank area is used as the measurement area for the conductance current of the sample 312.

[0071] Specifically, if a metallized film is selected as the conductor, the structure of the sample to be measured is a first conductor 311, a mask 314, a sample 312, and a second conductor 313. The upper electrode acts as the high-voltage electrode and faces downwards, contacting the upper surface of the sample 312, and the lower electrode acts as the ground electrode and faces upwards, contacting the lower surface of the sample 312.

[0072] The mask 314 selects a material with a breakdown strength higher than that of the sample 312 to ensure that the mask 314 does not break down before the sample 312 to be measured breaks down. A blank area 315 of a certain size is subtracted from the mask 314 material as a window to select the test area of the sample 312.

[0073] The entire structure of the sample 31 to be measured is divided into four layers, from top to bottom: the upper electrode, the mask 314, the sample 312, and the lower electrode. The upper electrode is the high-voltage electrode of the sample 312, and the voltage generated by the high-voltage power supply is directly supplied to this electrode; the mask 314 is a thin film with a breakdown strength greater than that of the sample 312, and a certain-sized area is subtracted from its center to control the test area of the sample 312; the lower electrode is the ground electrode of the sample 312, and this electrode is connected to the input of the inverting amplifier. Before each measurement, a certain voltage is pre-applied to the sample 312, and the four-layer structure is tightly bonded together by electrostatic force to eliminate the bubbles generated when placing the sample 312 and ensure good contact.

[0074] Optionally, the inverting variable-gain amplifier is an operational amplifier, and the models of the operational amplifier include at least one of LM741, AD829, AD823, and AD549.

[0075] Optionally, the inverting amplifier is an operational amplifier, and the models of the operational amplifier include at least one of LM741, AD829, AD823, and AD549.

[0076] Specifically, the inverting variable-gain amplifier in the reference channel and the inverting amplifier in the sample channel are both implemented by operational amplifiers, and common general-purpose operational amplifiers such as LM741, AD829, AD823, and AD549 can be selected.

[0077] Optionally, the models of the differential amplifier include at least one of INA148, INA132, INA105, INA597, INA157, INA106, and INA116, the models of the digital lock-in amplifier include at least one of SRS830 and SR865A, and the models of the voltage-controlled amplifier include at least one of VCA820, VCA810, and SSM2018T.

[0078] Specifically, the differential amplifier can select models such as INA148, INA132, INA105, INA597, INA157, INA106, and INA116.

[0079] The digital lock-in amplifier is used to detect the tiny signals in the circuit, that is, the capacitive components that need to be canceled, and output the relative amplitude of the signal with the same frequency as the reference input signal. The models of the digital lock-in amplifier can be SRS830, SR865A, etc.

[0080] The voltage-controlled amplifier receives the signal output from the digital lock-in amplifier and adjusts the reference channel signal to match the sample channel signal. The models of the voltage-controlled amplifier can be selected as VCA820, VCA810, SSM2018T, etc.

[0081] Temperature and humidity of the conductance current measurement device: To obtain the conductance of a sample under different temperature and humidity conditions, the sample can be placed in equipment such as a vacuum drying oven, and the conductance test can be carried out after the expected environmental conditions are reached.

[0082] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A conductive current measuring device, characterized in that: include: A voltage supply module, a reference channel, a sample channel and a feedback channel, wherein the sample channel includes a sample to be tested; The voltage supply module is connected to the reference channel and the sample channel, and is used to provide a linearly rising voltage with a superimposed sine wave to the reference channel and the sample channel; The reference channel is connected to the feedback channel, and the sample channel is connected to the feedback channel. The sample channel is used to measure the conductance current of the sample under test according to the voltage that rises linearly and is superimposed with a sine wave and output a sample channel signal. The reference channel is used to process the voltage that rises linearly and is superimposed with a sine wave and output a reference channel signal that approximately matches the sample channel signal. The feedback channel is used to process the reference channel signal and the sample channel signal and make them completely match.

2. The device according to claim 1, characterized in that The voltage supply module includes: a high voltage power supply and a voltage divider; The high-voltage power supply is connected to the voltage divider, and the high-voltage power supply is used to generate a voltage that rises linearly and is superimposed with a sine wave; The voltage divider is connected to the reference channel and the sample channel, and is used to adjust the amplitude of the voltage that rises linearly and superimposes the sine wave.

3. The device according to claim 1, characterized in that The reference channel includes: a voltage follower and an inverting variable gain amplifier; The voltage follower is connected between the voltage supply module and the inverting variable gain amplifier, and the voltage follower is used to keep the voltage input to the inverting variable gain amplifier stable; The inverting variable gain amplifier is connected to the feedback channel, and the inverting variable gain amplifier is used to increase the gain of the reference channel signal.

4. The device according to claim 1, characterized in that The sample channel also includes: an inverting amplifier; The sample under test is connected between the voltage supply module and the inverting amplifier, and the inverting amplifier is connected to the feedback channel. The inverting amplifier is used to integrate the resistive current passing through the sample under test when the conductance current is measured, adjust the capacitive current passing through the sample under test when the conductance current is measured, and output a sample channel signal that approximately matches the reference channel signal.

5. The device according to claim 1, characterized in that The feedback channel includes: a differential amplifier, a digital lock-in amplifier and a voltage-controlled amplifier; The differential amplifier is connected to the digital lock-in amplifier and the sample channel, and is used to differentially amplify the reference channel signal and the sample channel signal and transmit the differential amplification to the digital lock-in amplifier; The digital lock-in amplifier is connected to the voltage-controlled amplifier, and is used to monitor in real time whether the capacitive current components of the reference channel signal and the sample channel signal are completely offset, and output a signal with the same frequency as the reference input signal; The voltage-controlled amplifier is connected to the differential amplifier and the reference channel. The voltage-controlled amplifier is used to receive the output signal from the digital lock-in amplifier and adjust the reference channel signal to match the sample channel signal.

6. The device according to claim 1, characterized in that The sample to be tested includes: a first conductor, a sample, and a second conductor; The first conductor is an upper electrode, and the upper electrode is located on the upper surface of the sample; The second conductor is a lower electrode, and the lower electrode is located on the lower surface of the sample.

7. The device according to claim 6, characterized in that The sample under test further includes a mask, the mask is located between the first conductor and the sample, and the breakdown strength of the mask is greater than the breakdown strength of the sample; A blank area is reserved in the center of the mask, and the blank area is used as a measurement area for the sample conductance current.

8. The device according to claim 3, characterized in that The inverting variable gain amplifier is an operational amplifier, and the model of the operational amplifier includes: at least one of LM741, AD829, AD823, and AD549.

9. The device according to claim 4, characterized in that The inverting amplifier is an operational amplifier, and the model of the operational amplifier includes at least one of LM741, AD829, AD823, and AD549.

10. The device according to claim 5, characterized in that The models of the differential amplifier include: at least one of INA148, INA132, INA105, INA597, INA157, INA106, and INA116; the models of the digital lock-in amplifier include: at least one of SRS830 and SR865A; the models of the voltage-controlled amplifier include: at least one of VCA820, VCA810, and SSM2018T.

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