A current calibration method, device, equipment and medium

Abstract

The present invention relates to the technical field of current calibration, and discloses a current calibration method, device, equipment and medium. The method includes: after connecting the high-end side and the low-end side of the source measurement unit to the positive and negative electrodes of the component under test respectively, obtaining the measured current of the component under test and the measured current of the source measurement unit; obtaining the corresponding calibration parameters through the corresponding relationship between the measured current and the measured current; calibrating the measured current based on the calibration parameters to make the calibrated measured current consistent with the measured current; and after calibrating the measured current, under the condition that the source measurement unit outputs no load, measuring after outputting different equally spaced fixed voltages at the maximum voltage range to obtain voltage measurement values and current measurement values; using the voltage measurement values and the current measurement values to perform common-mode compensation on the current measurement error of the source measurement unit. The present invention focuses on the high-end acquisition of the digital current loop, can effectively avoid the influence of high common mode, and greatly improves the current accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of current calibration, and particularly relates to a current calibration method, device, equipment and medium. Background Art

[0002] A source meter, also known as a Source Meter Unit (SMU), is a test instrument integrating the functions of a voltage source, a current source, an electronic load, a voltmeter, and an ammeter. It can provide accurate direct current (or pulse) voltage or current output or absorption, and can simultaneously measure parameters such as current and voltage of a device under test (i.e., a Device Under Test, DUT, also known as a load).

[0003] Currently, in a digital current loop composed of source meters, the measurement of the loop current includes low-end acquisition and high-end acquisition. Among them, low-end acquisition directly measures the current between the load and the ground, and high-end acquisition measures the current between the power supply and the load. Low-end acquisition is prone to introducing branch current, thereby reducing the current accuracy of the loop. High-end acquisition can use a low-voltage operational amplifier to avoid the influence of high common mode, but it requires grounding processing, which is difficult in design. Therefore, there is an urgent need for a digital loop current calibration scheme for high-end acquisition to ensure the current accuracy in the digital current loop. Summary of the Invention

[0004] In view of this, the present invention provides a current calibration method, device, equipment and medium to solve the problems that the existing digital current loop cannot effectively avoid the influence of high common mode for high-end acquisition, and has complex design and low loop current accuracy.

[0005] In a first aspect, the present invention provides a current calibration method, which is applied to a digital current loop for high-end acquisition. The digital current loop includes a digital loop controller, a forward channel, and a current feedback channel. Among them, the forward channel is used to adjust the current accordingly according to the control of the digital loop controller, and it includes a digital-to-analog converter, a conditioning circuit, a power amplifier, and a sampling resistor. The current feedback channel is used to collect and feedback the corresponding loop current, and it includes a current acquisition front-end buffer, an isolated power supply, a high common mode amplifier, an instrumentation amplifier, a conditioning circuit, and an analog-to-digital converter. The current acquisition front-end buffer is powered separately by the isolated power supply, and the reference ground of the isolated power supply is equipotential with the output end of the power amplifier. The method includes:

[0006] After connecting the high-end side and the low-end side of the source meter to the positive and negative electrodes of the component under test respectively, obtain the measured current of the component under test and the measured current of the source meter.

[0007] Obtain the corresponding calibration parameter through the corresponding relationship between the measured current and the measured current.

[0008] The machine-measured current is calibrated based on the calibration parameters so that the calibrated machine-measured current is consistent with the meter-measured current; and after the machine-measured current is calibrated, different equally spaced fixed voltages are output at the maximum voltage level and then measured under the condition that the source measurement unit output is no-loaded, and corresponding voltage measurement values and current measurement values are obtained;

[0009] The voltage measurement value and the current measurement value are used to perform common mode compensation for the current measurement error of the source measurement unit.

[0010] The present invention focuses on the high-end acquisition of the digital current loop, obtains corresponding calibration parameters by measuring the machine-measured current of the component under test and the meter-measured current of the source measurement unit, calibrates the machine-measured current using the calibration parameters, and then measures different equally spaced fixed voltages at the maximum voltage level under the condition that the source measurement unit outputs no-load, obtains corresponding voltage measurement values and current measurement values, and uses the measurement values to perform common-mode compensation on the current measurement error of the source measurement unit, which can effectively avoid the gain error and common-mode influence of the high common-mode amplifier, thereby greatly improving the current accuracy of the digital current loop.

[0011] In an optional implementation, the current calibration method further includes:

[0012] Verify that the output of the high common-mode amplifier is in the linear region;

[0013] If it is in the linear region, the step of obtaining the machine-measured current of the component under test and the meter-measured current of the source measurement unit is performed;

[0014] If it is in the nonlinear area, the preset nonlinear working area avoidance operation is executed, and then the step of verifying whether the output of the high common mode amplifier is in the linear area is returned again; wherein the preset nonlinear working area avoidance operation at least includes using a preset reference source to DC bias the output of the high common mode amplifier, and using an instrument amplifier cascaded at the output end of the high common mode amplifier to eliminate the influence of the bias voltage on the corresponding signal conditioning path.

[0015] The present invention takes into account the situation that there is a sudden linearity change in the output voltage zero-crossing gain error when the high common-mode amplifier is working, and accordingly designs a verification process for whether the current output of the high common-mode amplifier is in a linear region. When it is in a nonlinear region, corresponding avoidance operations are taken to stagger the nonlinear region when the high common-mode amplifier is working, which can effectively avoid the influence of high common mode and thus help to improve the loop current accuracy.

[0016] In an optional implementation, obtaining a machine-measured current of a component under test and a meter-measured current of a source measurement unit includes:

[0017] Connect the positive and negative electrodes of the component under test to the corresponding ports on the high-end side and the low-end side of the four-wire measurement of the source measurement unit respectively;

[0018] Configure the component under test to the current measurement mode and perform a measurement to obtain the machine-measured current;

[0019] Perform equally spaced sampling at the preset current range of the source measurement unit to synchronously obtain the corresponding meter-measured current.

[0020] After configuring the high-end acquisition method of the digital current loop, the present invention respectively uses the component under test to obtain the corresponding machine-measured current and the meter-measured current of the source measurement unit, providing high-quality data for subsequent current calibration.

[0021] In an alternative embodiment, corresponding calibration parameters are obtained through the correspondence between the machine-measured current and the meter-measured current, including:

[0022] Obtain the correspondence between the current and the calibration parameters;

[0023] Input the machine-measured current and the meter-measured current into the correspondence and perform fitting to obtain the corresponding calibration parameters.

[0024] The present invention uses the correspondence between the current and the calibration parameters to fit the relationship between the machine-measured current and the meter-measured current, obtaining the corresponding calibration parameters, which can ensure the rationality of the calibration parameters and thus improve the accuracy of subsequent current calibration to a certain extent.

[0025] In an alternative embodiment, common-mode compensation is performed on the current measurement error of the source measurement unit using the voltage measurement value and the current measurement value, including:

[0026] Disconnect the component under test from the source measurement unit and configure the source measurement unit to the feedback mode;

[0027] Apply voltage points at equal intervals at the maximum voltage range and synchronously record the voltage measurement value and the current measurement value measured by the source measurement unit;

[0028] Determine the common-mode compensation parameter according to the voltage measurement value and the current measurement value;

[0029] Perform common-mode compensation on the current measurement error of the source measurement unit based on the common-mode compensation parameter.

[0030] After zero-point correction of the output of the high common-mode amplifier, the present invention also takes into account the common-mode rejection ability of the high common-mode amplifier, determines the corresponding common-mode compensation parameter in combination with the current accuracy description of the high-sampling common-ground system in the conventional architecture, and performs common-mode compensation on the current measurement error of the source measurement unit using the common-mode compensation parameter, which can comprehensively and effectively avoid the influence of high common mode, and thus greatly improve the current accuracy of the digital current loop.

[0031] In an alternative embodiment, determining the common-mode compensation parameter according to the voltage measurement value and the current measurement value includes:

[0032] Perform a linear fit on the voltage measurement value and the current measurement value to obtain a common-mode voltage-current relationship formula;

[0033] Determine the common-mode compensation parameter based on the common-mode voltage-current relationship formula.

[0034] The present invention determines the common-mode compensation parameter through the common-mode voltage-current relationship formula obtained by linear fitting, which has the advantages of simple and accurate calculation, and can improve the digital loop current accuracy to a certain extent.

[0035] In an optional implementation manner, before performing current calibration on the digital current loop collected at the high end, the current calibration method further includes: performing a preset temperature drift suppression measure, where the preset temperature drift suppression measure at least includes physically isolating the heating devices in the digital current loop, using a water-cooled heat dissipation system and an efficient air-cooled heat dissipation system to reduce the temperature rise of each device in the digital current loop, and performing a warm-up operation.

[0036] The present invention takes into account the overall temperature change of the table-measured current acquisition link. Before performing current calibration using the digital current loop collected at the high end, a series of temperature drift suppression measures are performed to avoid the influence of temperature on calibration, which can greatly reduce the influence of temperature on the current calibration result, and thus can significantly improve the current accuracy of the digital current loop.

[0037] In a second aspect, the present invention provides a current calibration device applied to a digital current loop collected at the high end. The digital current loop includes a digital loop controller, a forward channel, and a current feedback channel; wherein, the forward channel is used to adjust the current accordingly according to the control of the digital loop controller, and it includes a digital-to-analog converter, a conditioning circuit, a power amplifier, and a sampling resistor; the current feedback channel is used to collect and feedback the corresponding loop current, and it includes a current acquisition front-end buffer, an isolated power supply, a high common-mode amplifier, an instrumentation amplifier, a conditioning circuit, and an analog-to-digital converter. The current acquisition front-end buffer is independently powered by the isolated power supply, and the reference ground of the isolated power supply is equipotential with the output end of the power amplifier. The device includes:

[0038] A data acquisition module, configured to connect the high-end side and the low-end side of the source measurement unit to the positive and negative electrodes of the component under test respectively, and acquire the machine-measured current of the component under test and the table-measured current of the source measurement unit;

[0039] A parameter determination module, configured to obtain the corresponding calibration parameter through the correspondence between the machine-measured current and the table-measured current;

[0040] A zero - point calibration module is used to calibrate the machine - measured current based on calibration parameters so that the calibrated machine - measured current is consistent with the meter - measured current. After calibrating the machine - measured current, under the condition that the source measurement unit outputs no load, different equally - spaced fixed voltages are output at the maximum voltage range and then measured, and the corresponding voltage measurement values and current measurement values are obtained.

[0041] A common - mode compensation module is used to perform common - mode compensation on the current measurement error of the source measurement unit by using the voltage measurement value and the current measurement value.

[0042] The current calibration device of the present invention aims to solve the problem of low current accuracy in high - end acquisition in a digital current loop. Specifically, by obtaining corresponding calibration parameters from the machine - measured current of the component under test and the meter - measured current of the source measurement unit, after calibrating the machine - measured current using the calibration parameters, under the condition that the source measurement unit outputs no load, different equally - spaced fixed voltages are output at the maximum voltage range and then measured, and the corresponding voltage measurement values and current measurement values are obtained, and the current measurement error of the source measurement unit is compensated for common - mode using these measurement values, which can effectively avoid the gain error and common - mode influence of the high - common - mode amplifier and help to greatly improve the current accuracy of the digital current loop.

[0043] In a third aspect, the present invention provides an electronic device, including: a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to execute a current calibration method according to the first aspect or any corresponding embodiment thereof.

[0044] In a fourth aspect, the present invention provides a computer - readable storage medium, on which computer instructions are stored. The computer instructions are used to cause a computer to execute a current calibration method according to the first aspect or any corresponding embodiment thereof; and the computer - readable storage medium is also used to store calibration parameters and common - mode compensation parameters. Description of the Drawings

[0045] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following - described drawings are 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.

[0046] Figure 1 is the overall block diagram of the digital loop;

[0047] Figure 2 is the current loop architecture diagram of the digital loop;

[0048] Figure 3It is a graph of the high common-mode amplifier gain error;

[0049] Figure 4 It is a diagram illustrating the common-mode rejection ability of the high common-mode amplifier;

[0050] Figure 5 It is a schematic flowchart of the current calibration method according to an embodiment of the present invention;

[0051] Figure 6 It is a graph of the linearity before the measured inflection point avoidance;

[0052] Figure 7 It is a graph of the linearity after the measured inflection point avoidance;

[0053] Figure 8 It is a schematic flowchart of another current calibration method according to an embodiment of the present invention;

[0054] Figure 9 It is a schematic flowchart of the calibration scheme;

[0055] Figure 10 It is a block diagram of the structure of the current calibration device according to an embodiment of the present invention;

[0056] Figure 11 It is a schematic diagram of the structure of the electronic device according to an embodiment of the present invention. Detailed implementation manners

[0057] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. 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 protection scope of the present invention.

[0058] It should be noted that the current calibration method described in detail below in this embodiment is applied to the digital current loop for high-end acquisition. In practical applications, the digital loop is a technology used to adjust the system output in digital signal processing and is widely applied in fields such as communication and computers to achieve signal processing, transmission, and control. The digital loop usually consists of parts such as a digital signal processing module and a feedback loop. Its core idea is to digitally process the signal and use the feedback mechanism to adjust the system output to achieve specific performance indicators, such as stable output and accurate frequency tracking. High-end acquisition refers to directly measuring the current between the power supply (such as a battery or power rail) and the load, rather than the traditional low-end measurement (between the load and the ground). This type of acquisition method can detect load-to-ground short circuits, avoid ground loop interference, and is suitable for floating ground systems. However, there are challenges such as high common-mode voltage (which may be close to the power supply voltage) and the need for dedicated circuits to process high voltage difference signals. In addition, digital loop current calibration is a technology that adjusts the current measurement loop parameters (such as gain, offset, non-linear compensation) in real time through digital signal processing or a microcontroller to improve accuracy and stability.

[0059] In this embodiment, Figure 1 is the overall block diagram of the digital loop. It should be noted that in this embodiment, the digital loop is used to implement the related functions of the source measurement unit (i.e., SMU). That is, the digital loop can, according to the instructions from the upstream interface (i.e., connected to the main device), perform high-precision output (absorption) of voltage (or current) and high-precision synchronous acquisition of voltage (or current) between the HF(HI) and LF(LO) lines. Among them, HS(sense HI) and LS(sense LO) are used as the sense lines for acquisition. It should be noted that the related functions of HF(HI) and LF(LO), as well as the sense lines including HS(sense HI) and LS(sense LO), can refer to the related wiring meanings of the source measurement unit and will not be elaborated here. Refer to Figure 1 for the specific functions of each component in the digital loop, including:

[0060] 1. The upstream interface is used to communicate with the FPGA (Field Programmable Gate Array). High-speed communication methods such as PIXE (Particle Induced X-ray Emission, a method of bombarding a sample with particles generated by a particle accelerator to excite the sample to release characteristic X-rays), PCIE (Peripheral Component Interconnect Express, a high-speed serial point-to-point communication protocol for connecting high-performance peripherals inside a computer), and GTX (Gigabit Transceiver, a high-speed serial communication interface mainly used for high-speed and real-time transmission of large amounts of data in modern digital processing technology and computing technology) can be adopted. It provides configuration information and control commands for the digital loop, and receives the collected voltage and current data and loop status information.

[0061] 2. The FPGA mainly integrates a loop controller and a clamping protection system. It exchanges data with the upstream interface, controls the output of the Digital-to-Analog Converter (DAC), and collects the voltage and current outputs from the Analog-to-Digital Converter (ADC).

[0062] 3. DA (Digital to Analog), PA (Power Amplifier), and the sampling resistor together form the hardware forward channel of the SMU.

[0063] 4. The current conditioning module and AD (Analog to Digital) form the current acquisition channel; the voltage conditioning module and AD form the voltage acquisition channel.

[0064] 5. The BUFFER provides a Guard signal (i.e., a protection signal, the specific meaning of which can be understood adaptively by referring to relevant content in this field) to prevent HF (HI) and HS (sense HI) from leaking electricity. The Guard signal is at the same potential as HF (HI) and provides an equipotential shielding protection for HF (HI).

[0065] 6. The DUT (Device Under Test) is the device or equipment / unit under test.

[0066] It should be noted that since the digital loop includes a digital current loop and a digital voltage loop, this application focuses on the digital current loop for high-end acquisition. The digital current loop includes a digital loop controller, a forward channel, and a current feedback channel. Among them, the forward channel is used to adjust the current accordingly according to the control of the digital loop controller, and it includes a digital-to-analog converter, a conditioning circuit, a power amplifier, and a sampling resistor. The current feedback channel is used to collect and feedback the corresponding loop current, and it includes a current acquisition front-end buffer, an isolated power supply, a high common-mode amplifier, an instrumentation amplifier, a conditioning circuit, and an analog-to-digital converter. The current acquisition front-end buffer is powered separately by the isolated power supply, and the reference ground of the isolated power supply is equipotential with the output terminal of the power amplifier.

[0067] In this embodiment, Figure 2 is the architecture diagram of the digital loop current loop. It should be noted that the main functions of the digital current loop are to provide high-precision current output (or absorption) function, high-precision current acquisition function, and high-precision current clamping function. Specifically, referring to Figure 2 , the digital current loop is composed of three modules, namely the digital loop controller, the forward channel, and the current feedback channel in the FPGA. The specific functions of each component are described as follows:

[0068] 1. The digital loop controller is integrated in the FPGA and is mainly used for the control of the current loop to achieve fast, accurate, and stable current output (or absorption) and current clamping. Conventionally, a digital PID (Proportional Integral Differential) controller is used.

[0069] 2. The forward channel is mainly built by analog hardware circuits and is used to receive control signals and output (absorb) the magnitude of the current (or voltage). It mainly includes a DA, a conditioning circuit, a PA, and a sampling resistor. Note that the relevant content of the DA and PA is referred to the previous text and will not be repeated here.

[0070] 3. The current feedback channel (i.e., the current output (absorption) function) is also mainly built by analog hardware circuits and is used for high-precision acquisition of the output (absorbed) current. It is mainly composed of a buffer (BUFFER, BUF) at the front end of the acquisition, an isolated power supply that powers the BUF separately, a high common-mode amplifier (High Common-Mode Amplifier, HCMA), an instrumentation amplifier (Instrumentation Amplifier, IA), a high-precision reference source (used to provide the reference voltage Vref), a conditioning circuit, and an AD. Note that the relevant content of the AD is referred to the previous text and will not be repeated here.

[0071] It should be noted that HCMA is an electronic circuit that can effectively suppress common-mode signal interference and amplify differential-mode signals at the same time. Its core advantage lies in the high common-mode rejection ratio (CMRR), which is applied to the scenario of extracting weak signals in a strong noise environment. CMRR (i.e., common-mode rejection ratio = the ratio of the voltage amplification factor of the differential-mode signal to the absolute value of the voltage amplification factor of the common-mode signal) is a parameter that measures the ability of a differential amplifier in an analog circuit to suppress input common-mode signals and is an important parameter used to evaluate the suppression of common-mode noise in the hardware indicators of data acquisition products. Among them, the common-mode signal refers to the signal that exists simultaneously at both input terminals and has the same magnitude and phase, such as power supply noise, ground interference, or other external interferences. The common-mode rejection ratio determines the ability of the device to suppress interference signals by measuring the difference between the input common-mode signal and the output common-mode signal. It not only affects the accuracy of the operational amplifier circuit but also has an important impact on the electromagnetic interference performance of the circuit.

[0072] In this embodiment, the isolated power supply mainly supplies power to the pre-stage BUF for current acquisition and gives a reference to the PA output potential (that is, the ground of the power supply is connected to the output of PA). The advantage is that the BUF can use an operational amplifier powered by a low voltage, and then the temperature drift, noise, and leakage of the BUF can be controlled small enough to meet the usage requirements, thus ensuring the current acquisition accuracy requirement of three ten-thousandths.

[0073] In this embodiment, Figure 3 is the gain error curve graph of the high common-mode amplifier. It should be noted that this graph shows the gain errors measured under the conditions of different power supply voltages (i.e., each V in the figure S ), a load resistance R of 2 kΩ, and a gain G of 1, which is used to describe the output errors under different voltages. Among them, the horizontal axis represents the output voltage, with the unit of volt V; the vertical axis represents the output error, with the unit of 2 mV / DIV (mV / DIV is the voltage value (mV) represented by each grid (DIV) on the oscilloscope; in the oscilloscope, mV / DIV represents the number of millivolts represented by each grid in the vertical direction. For example, assuming the oscilloscope is set to 100 mV / DIV, then each grid on the display screen represents 100 millivolts). As can be seen from the figure, each gain error curve shows the change of the output error under different output voltages; the offset of the curve is to clearly display the characteristics of each curve; for V S = ±12V, there is a sudden change in linearity at the circled place when the voltage is zero, that is, the high common-mode amplifier operates in the non-linear region at zero point. In practical applications, to evaluate the overall comprehensive requirements of the high-sampling common-ground system with a conventional architecture for the high common-mode amplifier, the best gain error curve of the high common-mode amplifier that can be selected on the market currently is as Figure 3As shown in the figure, it can be seen that the gain error at the zero-crossing point of the output voltage has an inflection point where the linearity suddenly changes. So when using this high common-mode amplifier, it is necessary to stagger this nonlinear area to ensure the accurate acquisition of the loop current.

[0074] In this embodiment, Figure 4 This is a diagram illustrating the common-mode rejection capability of a high common-mode amplifier. It should be noted that the figure shows the characteristic parameters and CMRR of an operational amplifier as they change with temperature (i.e., the change in common-mode rejection ratio at different temperatures); the horizontal axis represents temperature in degrees Celsius, and the vertical axis represents CMRR in microvolts per volt μV / V; there are multiple curves in the figure, each representing a different sample (10 samples). As the temperature rises, the CMRR value decreases, but generally remains within a relatively stable range. Referring to the rectangular area in the figure, it can be seen that since the CMRR is 91dB (28.18uV / V) and there is a maximum CMRR temperature drift of 5uV / V in the temperature range of 25°C to 75°C, the total is 33.18uV / V. Considering the current acquisition accuracy of 0.03% (i.e., the industry standard) and leaving a 10-fold margin, the common-mode effect needs to be controlled to 30uV / V. However, the current 33.18uV / V exceeds 30uV / V. Therefore, in this embodiment, the superposition effect of other accuracy influencing quantities on the current acquisition link needs to be considered, that is, the common mode needs to be compensated.

[0075] It should be explained that μV / V represents the voltage ratio, which refers to the ratio of the output voltage (in μV) to the input voltage (in V) in a circuit. This ratio is usually used to describe the gain or attenuation characteristics of the circuit. For example, in electronic circuits, gain or attenuation refers to the degree of voltage change during the transmission of the signal, that is, μV / V can be used to quantify the circuit's ability to amplify or attenuate weak signals. For example, if the gain of the circuit is 10,000, the output voltage will be 10,000 times the input voltage; if the attenuation is 0.001, the output voltage will be one thousandth of the input voltage. In addition, μV / V can also be used to describe the sensitivity of sensors or other electronic devices. If the sensitivity of a sensor is 10,000 μV / V, it means that when the input voltage changes by 1 volt, the output voltage will change by 10,000 microvolts. This type of representation can accurately quantify the device's response to tiny voltage changes during measurement.

[0076] Based on this, an embodiment of the present invention provides an embodiment of a current calibration method. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0077] In this embodiment, a current calibration method is provided, which is applied to a digital current loop for high-end acquisition. Figure 5 It is a schematic flowchart of the current calibration method according to the embodiment of the present invention. As Figure 5 shown, the process includes the following steps:

[0078] Step S501: After connecting the high-end side and the low-end side of the source measurement unit to the positive and negative electrodes of the component under test respectively, obtain the measured current of the component under test and the measured current of the source measurement unit.

[0079] It should be noted that in this embodiment, the measured current collected by the component under test is used as reference data for corresponding processing of the measured current of the source measurement unit. Among them, the specific type of the component under test is not limited here and can be adaptively adjusted according to actual needs. For example, when the component under test is a digital multimeter (DMM), it is only for illustrative purposes.

[0080] Step S502: Obtain the corresponding calibration parameters through the correspondence between the measured current and the measured current.

[0081] In this embodiment, the calibration parameters can be determined according to the correspondence between the current and the calibration parameters. Among them, the specific content of this correspondence can be adaptively determined according to the fitting relationship between the actual current and the calibration parameters.

[0082] Step S503: Calibrate the measured current based on the calibration parameters to make the calibrated measured current consistent with the measured current; and after calibrating the measured current, under the condition that the source measurement unit outputs no load, output different equally spaced fixed voltages at the maximum voltage range and then measure, and correspondingly obtain the voltage measurement value and the current measurement value.

[0083] It should be noted that the process of calibrating the measured current in step S503 in this embodiment is essentially the calibration of the current at the voltage zero point (i.e., zero point calibration), aiming to reduce the gain error of the high common-mode amplifier and ensure that when the high common-mode amplifier is used, the gain error corresponding to the output voltage passing through the zero point is staggered and there is a linearity mutation inflection point. Figure 6 It is a linearity curve graph before avoiding the measured inflection point. It should be explained that in the figure, the "measured" on the horizontal axis is actually the measured voltage of the source measurement unit, and the "measured" on the vertical axis is actually the measured voltage of the component under test (such as DMM). In this embodiment, a reference source is used to solve the linearity mutation inflection point and lift the corresponding level offset. Specifically, adjust its output range of ±1V to the range of 1V - 3V, and use a reference source of 2.048V to perform DC level offset lifting; it should be noted that this 2.048V offset lifting voltage needs to be subtracted before the data enters the signal conditioning circuit, so an instrumentation amplifier is used for corresponding processing in this embodiment. Figure 7It is a linearity curve graph after avoiding the measured inflection point.

[0084] In this embodiment, the condition that the source measurement unit outputs no load substantially represents the condition that the Force HI / LO ports of the SMU are not connected to an external load. Specifically, under the condition that the SMU outputs no load and at the maximum voltage range of the SMU, the voltage FV (Force Voltage, output voltage, which means that during the voltage scan process, evenly distributed measurement points are generated at a fixed voltage step to correspondingly collect the output voltage) is sampled at equal intervals, and the corresponding voltage measurement value and current measurement value are measured.

[0085] Step S504, perform common-mode compensation on the current measurement error of the source measurement unit by using the voltage measurement value and the current measurement value.

[0086] In this embodiment, performing common-mode compensation on the current measurement error of the source measurement unit is essentially to improve the common-mode rejection ability of the high common-mode amplifier, that is, to compensate for the common mode to reduce the common-mode influence.

[0087] The current calibration method of the embodiment of the present invention focuses on the problem of low current accuracy in the high-end acquisition of the foregoing digital current loop. By obtaining the corresponding calibration parameters from the measured current of the component under test and the measured current of the source measurement unit, and using the calibration parameters to calibrate the measured current, under the condition that the source measurement unit outputs no load, different fixed voltages at equal intervals are output at the maximum voltage range and then measured, the corresponding voltage measurement value and current measurement value are obtained, and the measured value is used to perform common-mode compensation on the current measurement error of the source measurement unit, which can effectively avoid the gain error and common-mode influence of the high common-mode amplifier, and thus greatly improve the current accuracy of the digital current loop.

[0088] In this embodiment, a current calibration method is provided, which is applied to a digital current loop for high-end acquisition. Figure 8 It is a schematic flowchart of another current calibration method according to the embodiment of the present invention. In this embodiment, considering the overall temperature change of the measured current acquisition link, before performing current calibration using the digital current loop for high-end acquisition, a series of temperature drift suppression measures are executed to avoid the influence of temperature on calibration, which can reduce the influence of temperature on the current calibration result to a certain extent, and thus greatly improve the current accuracy. Therefore, before performing current calibration on the digital current loop for high-end acquisition, the current calibration method of this embodiment further includes: executing preset temperature drift suppression measures, where the preset temperature drift suppression measures at least include physically isolating the heating devices in the digital current loop, using a water-cooled heat dissipation system and a high-efficiency air-cooled heat dissipation system to reduce the temperature rise of each device in the digital current loop, and performing a warm-up operation. It should be noted that the relevant content of the water-cooled heat dissipation system and the high-efficiency air-cooled heat dissipation system in this embodiment can be referred to the well-known common sense in the art and will not be elaborated here.

[0089] In this embodiment, if Figure 8 As shown, the process of the current calibration method includes the following steps:

[0090] Step S801 , after the high-end side and the low-end side of the source measurement unit are connected to the positive and negative electrodes of the component under test respectively, the machine-measured current of the component under test and the meter-measured current of the source measurement unit are obtained.

[0091] It should be noted that before executing step S801, this embodiment takes into account the situation that the output voltage zero-crossing gain error of the high common-mode amplifier has a sudden linear change when it is working, and accordingly designs a verification process for whether the current output of the high common-mode amplifier is in the linear region to improve the loop current accuracy. Specifically, before obtaining the machine-measured current of the component under test and the meter-measured current of the source measurement unit, the current calibration method of this embodiment also includes:

[0092] Step A1, verify whether the output of the high common-mode amplifier is in the linear region.

[0093] In this embodiment, the specific verification method of whether the output of the high common-mode amplifier is in the linear region is not limited here, and is adaptively determined according to actual needs; for example, detecting whether the output of the high common-mode amplifier is linearly proportional to the input, or observing whether the output waveform is saturated or distorted when the input signal amplitude increases to a certain level, that is, whether the output signal has clipping, distortion or phase shift, etc., is only used as an example.

[0094] Step A2: If it is in the linear region, the step of obtaining the machine-measured current of the component under test and the meter-measured current of the source measurement unit is performed.

[0095] Step A3, if it is in the nonlinear area, then execute the preset nonlinear working area avoidance operation, and then return to the step of verifying whether the output of the high common mode amplifier is in the linear area; wherein the preset nonlinear working area avoidance operation at least includes using a preset reference source to DC bias the output of the high common mode amplifier, and using an instrument amplifier cascaded at the output end of the high common mode amplifier to eliminate the influence of the bias voltage on the corresponding signal conditioning path.

[0096] It should be noted that DC bias refers to superimposing a fixed DC voltage or current on an AC signal, so that the overall level of the signal is offset. In this embodiment, the bias voltage is used to avoid the situation where the output voltage zero-crossing gain error has a sudden linearity change when the high common-mode amplifier is working. Specifically, by taking corresponding measures to stagger the nonlinear region when the high common-mode amplifier is working, the high common-mode influence can be effectively avoided, thereby greatly improving the loop current accuracy.

[0097] In this embodiment, the above step S801 includes:

[0098] Step S8011: Connect the positive and negative electrodes of the component under test to the corresponding ports on the high - end side and low - end side in the four - wire measurement of the source measurement unit respectively.

[0099] Step S8012: Configure the component under test to the current measurement mode and perform measurement to obtain the machine - measured current.

[0100] Step S8013: Perform equally - spaced sampling at the preset current range of the source measurement unit to synchronously obtain the corresponding meter - measured current.

[0101] In this embodiment, through the data acquisition method of the source measurement unit in step S8013, the goal of synchronous measurement with the component under test can be achieved to eliminate the time deviation of data acquisition.

[0102] In the embodiment of the present invention, after configuring the high - end acquisition mode of the digital current loop, the component under test is respectively used to obtain the corresponding machine - measured current and the meter - measured current of the source measurement unit, providing high - quality data for subsequent current calibration.

[0103] Step S802: Obtain the corresponding calibration parameters according to the correspondence between the machine - measured current and the meter - measured current.

[0104] Specifically, the above step S802 includes:

[0105] Step S8021: Obtain the correspondence between the current and the calibration parameters.

[0106] In this embodiment, the correspondence between the current and the calibration parameters is determined according to the actual requirements. For example, referring to the current accuracy requirements of the high - sampling common - ground system of the conventional architecture (i.e., the current acquisition accuracy requirement of three ten - thousandths), which is not specifically limited here.

[0107] Step S8022: Input the machine - measured current and the meter - measured current into the correspondence and perform fitting to obtain the corresponding calibration parameters.

[0108] In this embodiment, the specific fitting method can be adaptively adjusted according to the actual data.

[0109] In the embodiment of the present invention, the correspondence between the current and the calibration parameters is used to fit the relationship between the machine - measured current and the meter - measured current to obtain the corresponding calibration parameters, which can ensure the rationality of the calibration parameters and further improve the accuracy of subsequent current calibration to a certain extent.

[0110] Step S803: Calibrate the machine - measured current based on the calibration parameters to make the calibrated machine - measured current consistent with the meter - measured current; and after calibrating the machine - measured current, under the condition that the source measurement unit outputs no load, output different equally - spaced fixed voltages at the maximum voltage range and then measure, and correspondingly obtain the voltage measurement value and the current measurement value. For details, please refer toFigure 5 Step S503 of the illustrated embodiment will not be elaborated herein.

[0111] Step S804: Use the voltage measurement value and the current measurement value to perform common-mode compensation on the current measurement error of the source measurement unit.

[0112] Specifically, the above step S804 includes:

[0113] Step S8041: Disconnect the component under test from the source measurement unit and configure the source measurement unit in the feedback mode.

[0114] It should be noted that the feedback mode of the source measurement unit is to form a closed-loop feedback loop to eliminate the influence of the external load, thereby realizing the stability and calibration function of high-precision output.

[0115] Step S8042: Apply voltage points at equal intervals under the maximum voltage range and synchronously record the voltage measurement value and the current measurement value measured by the source measurement unit.

[0116] Step S8043: Determine the common-mode compensation parameter according to the voltage measurement value and the current measurement value.

[0117] Specifically, the above step S8043 includes:

[0118] Step B1: Perform linear fitting on the voltage measurement value and the current measurement value to obtain the common-mode voltage-current relationship.

[0119] Step B2: Determine the common-mode compensation parameter based on the common-mode voltage-current relationship.

[0120] In this embodiment, the common-mode compensation parameter mainly characterizes the influence of voltage on current.

[0121] In the embodiment of the present invention, the common-mode compensation parameter is determined by the common-mode voltage-current relationship obtained through linear fitting, which has the advantages of simple and accurate calculation, and can improve the digital loop current accuracy to a certain extent.

[0122] Step S8044: Perform common-mode compensation on the current measurement error of the source measurement unit based on the common-mode compensation parameter.

[0123] In the embodiment of the present invention, after zero-point correction of the output of the high common-mode amplifier, considering the common-mode rejection ability of the high common-mode amplifier, the corresponding common-mode compensation parameter is determined by combining the current accuracy description of the high-sampling common-ground system in the conventional architecture, and the common-mode compensation parameter is used to perform common-mode compensation on the current measurement error of the source measurement unit, which can comprehensively and effectively avoid the influence of high common mode, and thus greatly improve the current accuracy of the digital current loop.

[0124] It should be noted that the current accuracy description of the high-sampling common-ground system in the conventional architecture is:

[0125]

[0126] Among them, MI is the measured current value, offsetI is the allowable current offset, MV is the measured voltage value, and λ is the system of the influence of voltage on current, and its unified unit is A / V.

[0127] The conventional current calibration formula is:

[0128]

[0129] Among them, x is the measured value of the meter (i.e., the reference value measured by the DMM), y is the measured value of the machine (i.e., the measured value actually measured by the SMU). Considering the need to compensate for the influence of the common mode, the actual calibration formula used is:

[0130]

[0131] Among them, v represents the measured voltage value at this moment MV , d represents the common mode influence coefficient (i.e., the influence coefficient of voltage on current, also called the compensation coefficient).

[0132] It can be seen from the above content that the physical meaning described by the current accuracy corresponds one-to-one with the calibration scheme; therefore, the current calibration in this embodiment needs to consider the current calibration at the voltage zero point and the calibration of the common mode influence, that is, the common mode compensation. Specifically, the calibration scheme can be referred to Figure 9 , and the process includes:

[0133] 1. Current calibration at the voltage zero point.

[0134] The first step: Verify the linearity of the signal chain route to ensure avoiding the zero-crossing non-linear inflection point of the high common mode amplifier.

[0135] In this embodiment, this step aims to ensure that the amplifier operates in the linear region, that is, to ensure that the linearity of the signal chain route for current acquisition is good enough, so as to avoid the zero-crossing non-linear inflection point of the gain error of the high common mode amplifier.

[0136] The second step: Connect the SMU and DMM devices, configure the measurement mode and synchronously collect the measured value of the meter MI(x) and the measured value of the machine MI(y).

[0137] In this embodiment, when the linearity is good enough, the HF (HI) and LF (LO) of the SMU are directly connected to the red and black connectors of the eight-and-a-half-digit DMM device correspondingly; the DMM is turned on to the current measurement mode, and the SMU equally spaces the current points FI in terms of the current range, and simultaneously starts the current measurement of the DMM and the current measurement of the SMU to obtain the corresponding measured value MI(x) and the machine-measured value MI(y).

[0138] Step 3: Calculate the calibration parameters k and b, and establish the linear relationship (y = kx + b) between the measured value x and the machine-measured value y.

[0139] In this embodiment, using the corresponding relationship between the measured value and the machine-measured value, y = kx + b, the calibration parameters k and b can be obtained. Specifically, the least squares method is used to fit x and y to calculate the calibration parameters k and b; based on the calibration parameters k and b, the linear calibration equation y = kx + b is determined.

[0140] Step 4: Apply the calibration parameters, import k and b into the system, and achieve the correction of y = x.

[0141] In this embodiment, the obtained k and b are imported into the digital current loop for calibration, and y and x are made equal to achieve zero-error correction, so that kx + b can be corrected; at this time, only the parameter dv remains in the calibration relation.

[0142] II. Calibration of common-mode influence (common-mode compensation).

[0143] Step 5: Disconnect the external connection, configure the internal feedback mode of the SMU, and float the HS / LS detection terminals.

[0144] In this embodiment, this step is used to eliminate the influence of the external load. Specifically, the SMU and the DMM are disconnected, the SMU connectors are floated, and HS (sense HI) and LS (sense LO) are configured for internal feedback.

[0145] It should be noted that in the SMU, when HS (Sense HI) and LS (Sense LO) are configured for internal feedback and the connectors are floated, the core of this mechanism is to achieve the stability and calibration function of high-precision output through closed-loop control. Specifically, when the Force HI / LO (HF / LF) ports of the SMU are floated (not connected to an external load), the HS / LS ports are directly short-circuited to the Force output terminal through the internal circuit, forming a closed-loop feedback loop, and then the self-error is eliminated through this internal feedback to ensure the accuracy of the measurement result.

[0146] Step 6: Under the maximum voltage range, sample the voltage FV at equal intervals, and record the MV voltage and the MI current.

[0147] In this embodiment, below the maximum voltage range, the voltage FV is sampled at equal intervals, and the corresponding measured voltage value MV and current value MI are measured by the machine. Then, the corresponding compensation coefficient d (unit: A / V) is calculated.

[0148] Step 7: Calculate the compensation coefficient d (i.e., the compensation parameter), import d (A / V) into the system, and complete the common-mode compensation.

[0149] In this embodiment, the measured voltage value MV and the current value MI are linearly fitted to obtain the common-mode voltage-current relationship; based on the common-mode voltage-current relationship, the compensation coefficient d is determined, where the unit of the compensation coefficient d is A / V. Then, the corresponding value of the compensation coefficient d is compensated into the calibration system, and the calibration compensation corresponding to y = kx + b + dv is completed.

[0150] It should be noted that the current acquisition link needs to consider the temperature change as a whole, and relevant measures need to be designed to keep the temperature change within the reachable range (i.e., minimize the temperature impact). Specifically, it includes considering the temperature drift impact of the key parameters of all devices on the link and then making targeted adjustments; the power or heating module should be kept as far away from the acquisition link as possible; water cooling is preferably used for heat dissipation; calibration is preferably carried out in the test environment; after the device is cold-started, it needs to warm up for a certain period of time (such as 20 minutes) before being tested and used.

[0151] In summary, the above current calibration scheme can greatly improve the current accuracy, and can meet the accuracy requirement of 0.03%, or even higher.

[0152] In this embodiment, a current calibration device is also provided. This device is used to implement the above embodiment and the preferred implementation manner, and those that have been described will not be repeated. As used hereinafter, the term "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0153] The present invention provides a current calibration device, which is applied to a digital current loop for high-end acquisition, such as Figure 10 shown, the device includes:

[0154] A data acquisition module 1001, which is used to connect the high-end side and the low-end side of the source measurement unit to the positive and negative electrodes of the component under test respectively, and then acquire the measured current of the component under test and the measured current of the source measurement unit.

[0155] A parameter determination module 1002, which is used to obtain the corresponding calibration parameters through the corresponding relationship between the measured current and the measured current.

[0156] The zero - point calibration module 1003 is used to calibrate the machine - measured current based on calibration parameters, so that the calibrated machine - measured current is consistent with the meter - measured current; and after calibrating the machine - measured current, under the condition that the source measurement unit outputs no load, it outputs different equally - spaced fixed voltages at the maximum voltage range and then measures, and correspondingly obtains voltage measurement values and current measurement values.

[0157] The common - mode compensation module 1004 is used to perform common - mode compensation on the current measurement error of the source measurement unit by using the voltage measurement value and the current measurement value.

[0158] In some alternative embodiments, the device further includes: a temperature - drift suppression module, which is used to perform a preset temperature - drift suppression measure before performing current calibration on the digital current loop collected at the high - end. Wherein, the preset temperature - drift suppression measure at least includes physically isolating the heating devices in the digital current loop, using a water - cooling heat - dissipation system and an efficient air - cooling heat - dissipation system to reduce the temperature rise of each device in the digital current loop, and performing a warm - up operation.

[0159] In some alternative embodiments, the device further includes: a region verification module, which is used to verify whether the output of the high - common - mode amplifier is in the linear region; if it is in the linear region, then perform the steps of obtaining the machine - measured current of the component under test and the meter - measured current of the source measurement unit; if it is in the non - linear region, then perform a preset non - linear working - area avoidance operation and then return to perform the step of verifying whether the output of the high - common - mode amplifier is in the linear region again; wherein, the preset non - linear working - area avoidance operation at least includes performing a DC bias on the output of the high - common - mode amplifier by using a preset reference source, and eliminating the influence of the bias voltage on the corresponding signal conditioning path through an instrumentation amplifier cascaded at the output end of the high - common - mode amplifier.

[0160] In some alternative embodiments, the data acquisition module 1001 includes: a first acquisition sub - module, a second acquisition sub - module, and a third acquisition sub - module; wherein, the first acquisition sub - module is used to connect the positive and negative poles of the component under test to the corresponding ports on the high - end side and the low - end side of the four - wire measurement of the source measurement unit respectively; the second acquisition sub - module is used to configure the component under test to the current measurement mode and perform measurement to obtain the machine - measured current; the third acquisition sub - module is used to perform equally - spaced sampling at the preset current range of the source measurement unit and synchronously obtain the corresponding meter - measured current.

[0161] In some alternative embodiments, the parameter determination module 1002 includes: a first determination sub - module and a second determination sub - module; wherein, the first determination sub - module is used to obtain the corresponding relationship between the current and the calibration parameters; the second determination sub - module is used to input the machine - measured current and the meter - measured current into the corresponding relationship and perform fitting to obtain the corresponding calibration parameters.

[0162] In some alternative embodiments, the common-mode compensation module 1004 includes: a first compensation sub-module, a second compensation sub-module, a third compensation sub-module, and a fourth compensation sub-module; wherein, the first compensation sub-module is configured to disconnect the component under test from the source measurement unit and configure the source measurement unit in a feedback mode; the second compensation sub-module is configured to apply voltage points at equal intervals under the maximum voltage range and synchronously record the voltage measurement values and current measurement values measured by the source measurement unit; the third compensation sub-module is configured to determine the common-mode compensation parameters based on the voltage measurement values and current measurement values; and the fourth compensation sub-module is configured to perform common-mode compensation on the current measurement error of the source measurement unit based on the common-mode compensation parameters.

[0163] In some alternative embodiments, the third compensation sub-module includes: a first compensation unit and a second compensation unit; wherein, the first compensation unit is configured to perform linear fitting on the voltage measurement values and current measurement values to obtain a common-mode voltage-current relationship; and the second compensation unit is configured to determine the common-mode compensation parameters based on the common-mode voltage-current relationship.

[0164] The further function descriptions of the above-mentioned various modules are the same as those in the corresponding embodiments above, and will not be elaborated here.

[0165] The current calibration device in this embodiment is presented in the form of functional units. Here, the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and a memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0166] The current calibration device according to the embodiment of the present invention can solve the problem of low current accuracy in high-end acquisition in a digital current loop. The corresponding zero-point calibration and common-mode compensation methods effectively avoid the gain error and common-mode influence of a high common-mode amplifier, thereby greatly improving the current accuracy of the digital current loop.

[0167] The embodiment of the present invention also provides an electronic device. Please refer to Figure 11 , Figure 11 which is a schematic structural diagram of the above-mentioned electronic device provided in an alternative embodiment of the present invention. As shown in Figure 11As shown, the electronic device includes: one or more processors 10, a memory 20, and interfaces for connecting the components, including a high-speed interface and a low-speed interface. Each component communicates with each other using different buses and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed within the electronic device, including instructions stored in the memory or on the memory to display graphical information of the GUI on an external input / output device (such as a display electronic device coupled to the interface). In some alternative embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple electronic devices can be connected, and each electronic device provides some necessary operations (for example, determined to be a server array, a set of blade servers, or a multi-processor system). Figure 11 In [the figure], a processor 10 is taken as an example.

[0168] The processor 10 can be a central processing unit, a network processor, or a combination thereof. Among them, the processor 10 can further include a hardware chip. The above hardware chip can be an application-specific integrated circuit, a programmable logic device, or a combination thereof. The above programmable logic device can be a complex programmable logic device, a field programmable gate array, a generic array logic, or any combination thereof.

[0169] Among them, the memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiments.

[0170] The memory 20 can include a program storage area and a data storage area. Among them, the program storage area can store an operating system and application programs required for at least one function; the data storage area can store data created according to the use of the electronic device and the like. In addition, the memory 20 can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some alternative embodiments, the memory 20 can optionally include a memory remotely set relative to the processor 10, and these remote memories can be connected to the electronic device through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0171] The memory 20 can include a volatile memory, such as a random access memory; the memory can also include a non-volatile memory, such as a flash memory, a hard disk, or a solid-state drive; the memory 20 can also include a combination of the above types of memories.

[0172] The electronic device further includes a communication interface 30 for the main control chip to communicate with other electronic devices or a communication network.

[0173] In an embodiment of the present invention, a computer-readable storage medium is further provided. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored as such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memories. It can be understood that a computer, a processor, a microprocessor main control chip, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiment is implemented; and the computer-readable storage medium of this embodiment is further used to store calibration parameters and common-mode compensation parameters, that is, after the present application executes the current calibration method shown in the above embodiment, corresponding calibration parameters and common-mode compensation parameters can be obtained, and after storing them, it is convenient for subsequent direct use.

[0174] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A current calibration method, characterized in that, A digital current loop applied to high-end acquisition is used to implement relevant functions of a source measurement unit. The digital current loop includes a digital loop controller, a forward channel, and a current feedback channel. Among them, the forward channel is used to adjust the current accordingly according to the control of the digital loop controller, and it includes a digital-to-analog converter, a conditioning circuit, a power amplifier, and a sampling resistor. The current feedback channel is used to collect and feedback the corresponding loop current, and it includes a current acquisition front-end buffer, an isolated power supply, a high common-mode amplifier, an instrumentation amplifier, a conditioning circuit, and an analog-to-digital converter. The current acquisition front-end buffer is powered separately by the isolated power supply, and the reference ground of the isolated power supply is equipotential with the output end of the power amplifier. The method includes: After connecting the high-end side and the low-end side of the source measurement unit to the positive and negative electrodes of the component under test respectively, obtain the measured current of the component under test and the measured current of the source measurement unit. Obtain the corresponding calibration parameters through the corresponding relationship between the measured current of the component under test and the measured current of the source measurement unit. Calibrate the measured current of the component under test based on the calibration parameters so that the calibrated measured current of the component under test is consistent with the measured current of the source measurement unit. After calibrating the measured current of the component under test, under the condition that the source measurement unit outputs no load, measure after outputting different equally spaced fixed voltages at the maximum voltage range, and correspondingly obtain voltage measurement values and current measurement values. Perform common-mode compensation on the current measurement error of the source measurement unit by using the voltage measurement value and the current measurement value, including: Disconnect the component under test from the source measurement unit and configure the source measurement unit to the feedback mode. Apply voltage points at equal intervals within the maximum voltage range and synchronously record the voltage measurement values and current measurement values measured by the source measurement unit. Determine the common-mode compensation parameters according to the voltage measurement value and the current measurement value, including: Perform linear fitting on the voltage measurement value and the current measurement value to obtain a common-mode voltage-current relationship formula. Determine the common-mode compensation parameters based on the common-mode voltage-current relationship formula. Perform common-mode compensation on the current measurement error of the source measurement unit based on the common-mode compensation parameters.

2. The current calibration method according to claim 1, wherein The method further includes: Verify whether the output of the high common-mode amplifier is in the linear region. If it is in the linear region, execute the step of obtaining the measured current of the component under test and the measured current of the source measurement unit. If it is in the non-linear region, perform a preset non-linear working area avoidance operation and then return to execute the step of verifying whether the output of the high common-mode amplifier is in the linear region again. Among them, the preset non-linear working area avoidance operation at least includes performing DC biasing on the output of the high common-mode amplifier by using a preset reference source, and eliminating the influence of the bias voltage on the corresponding signal conditioning path through the instrumentation amplifier cascaded at the output end of the high common-mode amplifier.

3. The current calibration method according to claim 1, characterized in that The obtaining of the measured current of the component under test and the measured current of the source measurement unit includes: Connect the positive and negative electrodes of the component under test to the corresponding ports of the high-end side and the low-end side in the four-wire measurement of the source measurement unit respectively. Configure the component under test to the current measurement mode and perform measurement to obtain the measured current. Perform equally-spaced sampling at the preset current range of the source measurement unit to synchronously obtain the corresponding measured current.

4. The current calibration method according to claim 1, characterized in that Obtain the corresponding calibration parameters through the correspondence between the machine-measured current and the table-measured current, including: Obtain the correspondence between current and calibration parameters; Input the machine-measured current and the table-measured current into the correspondence and perform fitting to obtain the corresponding calibration parameters.

5. The current calibration method according to any one of claims 1 to 4, characterized in that Before performing current calibration on the digital current loop for high-end acquisition, the method further includes: performing a preset temperature drift suppression measure, where the preset temperature drift suppression measure at least includes physically isolating the heating components in the digital current loop, using a water-cooling heat dissipation system and an efficient air-cooling heat dissipation system to reduce the temperature rise of each component in the digital current loop, and performing a warm-up operation.

6. A current calibration device, characterized in that, Applied to the digital current loop for high-end acquisition and using the digital current loop to implement the relevant functions of the source measurement unit. The digital current loop includes a digital loop controller, a forward channel, and a current feedback channel; wherein, the forward channel is used to adjust the current accordingly according to the control of the digital loop controller, and it includes a digital-to-analog converter, a conditioning circuit, a power amplifier, and a sampling resistor; the current feedback channel is used to collect and feedback the corresponding loop current, and it includes a current acquisition front-end buffer, an isolated power supply, a high common-mode amplifier, an instrumentation amplifier, a conditioning circuit, and an analog-to-digital converter. The current acquisition front-end buffer is powered separately by the isolated power supply and the reference ground of the isolated power supply is equipotential with the output terminal of the power amplifier. The device includes: A data acquisition module, configured to connect the high-end side and the low-end side of the source measurement unit to the positive and negative electrodes of the component under test respectively, and obtain the machine-measured current of the component under test and the table-measured current of the source measurement unit; A parameter determination module, configured to obtain the corresponding calibration parameters through the correspondence between the machine-measured current and the table-measured current; A zero-point calibration module, configured to calibrate the machine-measured current based on the calibration parameters to make the calibrated machine-measured current consistent with the table-measured current; and after calibrating the machine-measured current, under the condition that the source measurement unit outputs no load, output different equally-spaced fixed voltages at the maximum voltage range and then measure, and correspondingly obtain voltage measurement values and current measurement values; A common-mode compensation module, configured to perform common-mode compensation on the current measurement error of the source measurement unit by using the voltage measurement values and the current measurement values, including: Disconnect the component under test from the source measurement unit and configure the source measurement unit to the feedback mode; Apply voltage points at equal intervals under the maximum voltage range and synchronously record the voltage measurement values and current measurement values measured by the source measurement unit; Determine the common-mode compensation parameters according to the voltage measurement values and the current measurement values, including: Perform linear fitting on the voltage measurement values and the current measurement values to obtain a common-mode voltage-current relationship; Determine the common-mode compensation parameters based on the common-mode voltage-current relationship; Perform common-mode compensation on the current measurement error of the source measurement unit based on the common-mode compensation parameters.

7. An electronic device, characterized in that, The electronic device includes: a memory and a processor, which are communicatively connected to each other. Computer instructions are stored in the memory, and the processor executes the computer instructions to perform the current calibration method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, Computer instructions are stored on the computer-readable storage medium, and the computer instructions are used to cause a computer to perform the current calibration method according to any one of claims 1 to 5; and the computer-readable storage medium is further used to store calibration parameters and common-mode compensation parameters.

Images