VI source common mode compensation device and VI source common mode compensation method

Abstract

The invention relates to a VI source common-mode compensation device and a VI source common-mode compensation method. A current measuring circuit detects the output current of a driving circuit, a voltage measuring circuit detects the differential voltage between a high-end voltage line HS and a low-end voltage line LS, and an LS voltage measuring circuit detects the voltage to ground of the low-end voltage line LS. The control unit respectively analyzes the received current measurement differential digital signal, the voltage measurement differential digital signal and the LS measurement digital signal to obtain a current measurement value, a voltage measurement value and an LS voltage measurement value; and a current measurement correction value and a voltage measurement correction value are obtained through analysis according to the current measurement value, the voltage measurement value, the LS voltage measurement value and a preset calibration coefficient, and feedback regulation is performed based on the current measurement correction value and the voltage measurement correction value to output a control signal to the driving circuit. Errors caused by common-mode voltage to current measurement and voltage measurement can be effectively reduced, and the voltage / current measurement precision is improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor testing technology, and in particular to a VI source common-mode compensation device and a VI source common-mode compensation method. Background Technology

[0002] With the rapid development of new energy and communication electronic products, the demand for high-current testing of power semiconductors, power ICs, and integrated circuits is expanding, placing increasingly higher demands on the accuracy and stability of voltage and current sources (VI sources). VI sources typically employ a four-wire Kelvin connection: High Force (HF), High Sense (HS), Low Force (LF), and Low Sense (LS). Current flows out (or into) the High Force (HF) current line and back (or out) the Low Sense (LF) current line.

[0003] When the VI source is calibrated and operating normally using a four-wire Kelvin connection, the common-mode voltages of the voltage measurement circuit and the current measurement circuit are different. The common-mode rejection ratios of the voltage measurement circuit and the current measurement circuit are limited, which causes the measurement results to be affected by the common-mode voltage, resulting in a decrease in voltage / current measurement accuracy. This is especially true in low-end current sampling applications where the VI source has a high current output, where the common-mode voltage affects the accuracy of the measured voltage. In high-end current sampling applications where the VI source has a high voltage output, the common-mode voltage affects the accuracy of the measured current. Summary of the Invention

[0004] Therefore, it is necessary to provide a VI source common mode compensation device and a VI source common mode compensation method that can improve measurement accuracy in response to the above problems.

[0005] The first aspect of this application provides a VI source common-mode compensation device, comprising:

[0006] The driving circuit is connected to the device under test (DUT) via the high-end current line HF, and outputs an excitation signal to the DUT according to the control signal sent by the control unit.

[0007] A current measurement circuit is connected to the drive circuit, detects the output current of the drive circuit, converts it into a current measurement differential digital signal, and sends it to the control unit.

[0008] The voltage measurement circuit is connected to the device under test through a high-side voltage line HS and a low-side voltage line LS. It detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS, converts it into a voltage measurement differential digital signal, and sends it to the control unit.

[0009] The LS voltage measurement circuit, connected to the voltage measurement circuit, detects the voltage to ground of the low-end voltage line LS, converts it into an LS measurement digital signal and sends it to the control unit;

[0010] The control unit is connected to the drive circuit, the current measurement circuit, the voltage measurement circuit, and the LS voltage measurement circuit. It analyzes the received differential digital signals for current measurement, voltage measurement, and LS measurement to obtain the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Based on the current measurement value, voltage measurement value, LS voltage measurement value, and a preset calibration coefficient, it analyzes and obtains the current measurement correction value and voltage measurement correction value. The control unit performs feedback adjustment based on the current measurement correction value and voltage measurement correction value, and outputs a control signal to the drive circuit.

[0011] In one embodiment, the VI source common-mode compensation device further includes a multimeter for detecting the voltage / output current across the load; the calibration coefficient is obtained by calibrating based on the current measurement value, voltage measurement value, LS voltage measurement value detected by the common-mode compensation device under different load conditions, and the voltage / output current across the load read by the multimeter.

[0012] In one embodiment, the calibration coefficients include current measurement calibration coefficients, voltage measurement calibration coefficients, LS voltage measurement calibration coefficients, voltage measurement common-mode compensation coefficients, and current measurement common-mode compensation coefficients;

[0013] The control unit corrects the current measurement value MI0 according to the current measurement calibration coefficient to obtain the current measurement value MI1, corrects the voltage measurement value MV0 according to the voltage measurement calibration coefficient to obtain the voltage measurement value MV1, and corrects the LS voltage measurement value MLS0 according to the LS voltage measurement calibration coefficient to obtain the LS voltage measurement value MLS1.

[0014] The control unit corrects the LS voltage measurement value MLS1 and the voltage measurement value MV1 according to the voltage measurement common-mode compensation coefficient, respectively, to obtain the voltage measurement correction value MV and the HS terminal voltage correction value MHS, respectively. The control unit corrects the current measurement value MI1 according to the current measurement common-mode compensation coefficient and the HS terminal voltage correction value MHS, to obtain the current measurement correction value MI.

[0015] In one embodiment, the formula for calculating the voltage measurement correction value MV is:

[0016] MV = MV0 * kmv + bmv + (MLS0 * kls + bls)* kvcom + bvcom

[0017] Where kmv and bmv are voltage measurement calibration coefficients, kls and bls are LS voltage measurement calibration coefficients, and kvcom and bvcom are voltage measurement common-mode compensation coefficients.

[0018] In one embodiment, the formula for calculating the current measurement correction value MI is:

[0019] MI = MI0 * kmi + bmi +[ MV0 * kmv + bmv + (MLS0 * kls + bls)*(1+kvcom) + bvcom ] * kicom + bicom

[0020] Where kmi and bmi are current measurement calibration coefficients, kmv and bmv are voltage measurement calibration coefficients, kls and bls are LS voltage measurement calibration coefficients, kvcom and bvcom are voltage measurement common-mode compensation coefficients, and kicom and bicom are current measurement common-mode compensation coefficients.

[0021] In one embodiment, the drive circuit includes a digital-to-analog converter and a power amplifier. The digital-to-analog converter is connected to the control unit and the power amplifier. The power amplifier is connected to the device under test (DUT) via a high-side current line HF. The DUT is connected to the internal ground of the drive circuit via a low-side current line LF.

[0022] In one embodiment, the current measurement circuit includes a current sampling resistor, a follower operational amplifier U1, a follower operational amplifier U2, a differential operational amplifier U3, and an analog-to-digital converter (ADC1). The current sampling resistor is connected in series on the high-side current line HF. The non-inverting input of the follower operational amplifier U1 is connected to the first terminal of the current sampling resistor. The inverting input of the follower operational amplifier U1 is connected to the output of the follower operational amplifier U1 and the first input of the differential operational amplifier U3. The non-inverting input of the follower operational amplifier U2 is connected to the second terminal of the current sampling resistor. The inverting input of the follower operational amplifier U2 is connected to the output of the follower operational amplifier U2 and the second input of the differential operational amplifier U3. The output of the differential operational amplifier U3 is connected to the control unit through the ADC1.

[0023] In one embodiment, the voltage measurement circuit includes a follower operational amplifier U4, a follower operational amplifier U5, a differential operational amplifier U6, and an analog-to-digital converter ADC2. The non-inverting input of the follower operational amplifier U4 is connected to the high-side voltage line HS. The inverting input of the follower operational amplifier U4 is connected to the output of the follower operational amplifier U4 and the first input of the differential operational amplifier U6. The non-inverting input of the follower operational amplifier U5 is connected to the low-side voltage line LS. The inverting input of the follower operational amplifier U5 is connected to the output of the follower operational amplifier U5 and the second input of the differential operational amplifier U6. The output of the differential operational amplifier U6 is connected to the control unit through the analog-to-digital converter ADC2.

[0024] In one embodiment, the LS voltage measurement circuit includes a differential operational amplifier U7 and an analog-to-digital converter ADC3. The first input terminal of the differential operational amplifier U7 is connected to the output terminal of the follower operational amplifier U5, the second input terminal of the differential operational amplifier U7 is connected to the internal ground terminal of the drive circuit, and the output terminal of the differential operational amplifier U7 is connected to the control unit through the analog-to-digital converter ADC3.

[0025] A second aspect of this application provides a common-mode compensation method for a VI source, applied to a control unit in a VI source common-mode compensation device. The common-mode compensation method includes:

[0026] The received differential digital signals for current measurement, voltage measurement, and LS measurement are analyzed to obtain the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Specifically, the current measurement circuit detects the output current of the drive circuit and converts it into a differential digital signal for current measurement, which is then sent to the control unit. The voltage measurement circuit detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS and converts it into a differential digital signal for voltage measurement, which is then sent to the control unit. The LS voltage measurement circuit detects the voltage to ground of the low-side voltage line LS and converts it into a digital signal for LS measurement, which is then sent to the control unit.

[0027] The current measurement correction value and the voltage measurement correction value are obtained by analyzing the current measurement value, the voltage measurement value, the LS voltage measurement value, and the preset calibration coefficient;

[0028] Based on the current measurement correction value and the voltage measurement correction value, a feedback adjustment is performed to output a control signal to the drive circuit; wherein, the drive circuit is connected to the device under test through the high-side current line HF, and outputs an excitation signal to the device under test according to the control signal sent by the control unit.

[0029] In one embodiment, the method further includes:

[0030] The calibration coefficient is determined by calibrating based on the current measurement, voltage measurement, LS voltage measurement, and the voltage / output current across the load read by the multimeter under different load conditions.

[0031] In one embodiment, the calibration coefficients include current measurement calibration coefficients, voltage measurement calibration coefficients, LS voltage measurement calibration coefficients, voltage measurement common-mode compensation coefficients, and current measurement common-mode compensation coefficients; the step of analyzing and obtaining current measurement correction values ​​and voltage measurement correction values ​​based on the current measurement value, the voltage measurement value, the LS voltage measurement, and the preset calibration coefficients includes:

[0032] The current measurement value MI0 is corrected according to the current measurement calibration coefficient to obtain the current measurement value MI1; the voltage measurement value MV0 is corrected according to the voltage measurement calibration coefficient to obtain the voltage measurement value MV1; and the LS voltage measurement value MLS0 is corrected according to the LS voltage measurement calibration coefficient to obtain the LS voltage measurement value MLS1.

[0033] The voltage measurement values ​​MLS1 and MV1 are corrected according to the common-mode compensation coefficient of the voltage measurement to obtain the voltage measurement correction value MV and the HS terminal voltage correction value MHS, respectively. The current measurement value MI1 is corrected according to the common-mode compensation coefficient of the current measurement and the HS terminal voltage correction value MHS to obtain the current measurement correction value MI.

[0034] In one embodiment, the calibration coefficients include LS voltage measurement calibration coefficients; determining the calibration coefficients includes:

[0035] When the VI source is connected to the load RLoad3 and the load RLoad4 is connected in series in the low-end current line LF, the drive circuit is controlled to output p groups of different excitation voltages. The LS voltage measurement value MLS0[p] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage meter measurement value MVR4[p] across the load RLoad4 is read by a multimeter.

[0036] The calibration coefficient for LS voltage measurement is calculated by performing linear fitting based on the LS voltage measurement value MLS0[p] and the voltmeter measurement value MVR4[p].

[0037] In one embodiment, the calibration coefficients further include voltage measurement common-mode compensation coefficients; determining the calibration coefficients further includes:

[0038] When the VI source is connected to the load RLoad3 and the load RLoad4 is connected in series in the low-end current line LF, the drive circuit is controlled to output q different excitation voltages. The LS voltage measurement value MLS0[q] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage measurement value MV0[q] is determined according to the voltage measurement differential digital signal output by the voltage measurement circuit. The voltage meter measurement value MVR3[q] at both ends of the load RLoad3 is read by a multimeter.

[0039] The voltage measurement value MV1[q] is obtained by correcting the voltage measurement value MV0[q] and the voltage measurement calibration coefficient. The LS voltage measurement value MLS0[q] is obtained by correcting the LS voltage measurement value MLS1[q] and the LS voltage measurement calibration coefficient. The voltage measurement common-mode error Mvcom[q] is calculated and determined based on the voltage measurement value MV1[q] and the voltmeter measurement value MVR3[q]. The voltage measurement common-mode error Mvcom[q] and the LS voltage measurement value MLS1[q] are linearly fitted to calculate the voltage measurement common-mode compensation coefficient.

[0040] In one embodiment, the calibration coefficients further include current measurement common-mode compensation coefficients; determining the calibration coefficients further includes:

[0041] When the VI source is connected to the load RLoad5, the drive circuit is controlled to output x different excitation voltages. The LS voltage measurement value MLS0[x] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage measurement value MV0[x] is determined according to the voltage measurement differential digital signal output by the voltage measurement circuit. The current measurement value MI0[x] is determined according to the current measurement differential digital signal output by the current measurement circuit. The output ammeter measurement value MIR5[x] of the load RLoad5 is read by a multimeter.

[0042] The voltage measurement value MV1[x] is obtained by correcting the voltage measurement value MV0[x] and the voltage measurement calibration coefficient. The LS voltage measurement value MLS0[x] and the LS voltage measurement calibration coefficient are also corrected to obtain the LS voltage measurement value MLS1[x]. The current measurement value MI0[x] and the current measurement calibration coefficient are also corrected to obtain the current measurement value MI1[x]. The HS terminal voltage correction value MHS[x] is calculated and determined based on the voltage measurement value MV1[x], the LS voltage measurement value MLS1[x], and the voltage measurement common-mode compensation coefficient. The current measurement common-mode error Micom[x] is calculated and determined based on the current measurement value MI1[x] and the output ammeter measurement value MIR5[x]. The current measurement common-mode error Micom[x] and the HS terminal voltage correction value MHS[x] are linearly fitted to obtain the current measurement common-mode compensation coefficient.

[0043] In the aforementioned VI source common-mode compensation device and method, the drive circuit is connected to the device under test (DUT) via the high-side current line HF, and outputs an excitation signal to the DUT according to the control signal sent by the control unit. The current measurement circuit detects the output current of the drive circuit, converts it into a differential digital current signal, and sends it to the control unit. The voltage measurement circuit detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS, converts it into a differential digital voltage signal, and sends it to the control unit. The LS voltage measurement circuit detects the voltage to ground of the low-side voltage line LS, converts it into a digital LS measurement signal, and sends it to the control unit. The control unit analyzes the received differential digital current signal, differential voltage signal, and LS measurement signal to obtain the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Based on the current measurement value, voltage measurement value, LS voltage measurement value, and preset calibration coefficients, it analyzes to obtain the current measurement correction value and voltage measurement correction value. Based on the current measurement correction value and voltage measurement correction value, it performs feedback adjustment and outputs a control signal to the drive circuit. By separately detecting the output current of the drive circuit, the voltage to ground of the low-side voltage line LS, and the differential voltage between the high-side voltage line HS and the low-side voltage line LS, and converting them into digital quantities to calculate the current measurement correction value and the voltage measurement correction value, the error caused by the common-mode voltage to the current measurement and voltage measurement can be effectively reduced, thus improving the accuracy of current / voltage measurement. Attached Figure Description

[0044] Figure 1 This is a structural block diagram of the VI source common mode compensation device in one embodiment;

[0045] Figure 2 This is a schematic diagram of the structural principle of the VI source common mode compensation device in one embodiment;

[0046] Figure 3 This is a schematic diagram illustrating the calculation principle of voltage measurement correction value MV and current measurement correction value MI in one embodiment;

[0047] Figure 4 and 5 Here is a structural principle and flowchart of voltage measurement calibration in one embodiment;

[0048] Figure 6 and 7 Here is a structural principle and flowchart of current measurement calibration in one embodiment;

[0049] Figure 8 and 9 Here is a structural principle and flowchart of LS voltage measurement calibration in one embodiment;

[0050] Figure 10 and 11 Here is a structural principle and flowchart of voltage measurement common-mode compensation calibration in one embodiment;

[0051] Figure 12 and 13 This is a structural principle and flowchart of current measurement common-mode compensation calibration in one embodiment. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. It is understood that the term "connection" in the following embodiments, if the connected circuits, modules, units, etc., transmit electrical signals or data to each other, should be understood as "electrical connection," "communication connection," etc.

[0054] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0055] In existing technologies, for voltage sampling: during calibration, the output is typically an unloaded or megaohm-level resistive load. The LS is grounded through the LF, and the voltage drop across the LF is very small, essentially negligible. Therefore, it can be considered that the HS and LS are calibrated under a common-mode voltage of 0. However, during normal operation, the LS voltage will rise to varying degrees depending on the application scenario, mainly due to the voltage drop across the LF line. In scenarios with high LF line impedance or high current, the LS will experience a significant voltage rise, and the extent of this rise will vary depending on the current magnitude and line impedance. Therefore, under normal operation, the HS and LS measurement links will have varying common-mode voltages, resulting in common-mode errors beyond calibration. For high-side current sampling: during current calibration, the load is typically an ohm-level or milliohm-level resistive load. The HF is grounded through the load resistor and the LF. The potential of the sampling resistor closest to the HF is close to 0, meaning that current sampling is calibrated under a common-mode voltage close to 0. During normal operation, the HF voltage of high-side current sampling will rise to varying degrees depending on the application scenario, mainly due to the voltage drop across the load resistor. In high-voltage output scenarios, the measurement error caused by the common-mode voltage is particularly significant.

[0056] Therefore, as Figure 1 and Figure 2 As shown, a common-mode compensation device for a VI source is provided. It adopts the Kelvin four-wire method for output and improves the hardware circuit of the VI source measurement link by adding an LS voltage measurement circuit to collect the LS-to-ground voltage. Then, based on the current measurement calibration coefficient, voltage measurement calibration coefficient, LS voltage measurement calibration coefficient, voltage measurement common-mode compensation coefficient, and current measurement common-mode compensation coefficient, a common-mode compensation algorithm is performed to obtain the current measurement correction value and voltage measurement correction value. This effectively reduces the error caused by the common-mode voltage to the current and voltage measurements and improves the accuracy of voltage and current measurement.

[0057] Specifically, the compensation device includes: a drive circuit 110, a current measurement circuit 120, a voltage measurement circuit 130, an LS voltage measurement circuit 140, and a control unit 150. The drive circuit 110 is connected to the device under test (DUT) via the high-side current line HF, and outputs an excitation signal to the DUT according to the control signal sent by the control unit 150, applying voltage / current excitation to the DUT. The current measurement circuit 120 is connected to the drive circuit 110, detects the output current of the drive circuit 110, converts it into a differential digital signal for current measurement, and sends it to the control unit 150. The voltage measurement circuit 130 is connected to the DUT via the high-side voltage line HS and the low-side voltage line LS, detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS, converts it into a differential digital signal for voltage measurement, and sends it to the control unit 150. 0; The LS voltage measurement circuit 140 is connected to the voltage measurement circuit 130, detects the voltage to ground of the low-side voltage line LS, converts it into an LS measurement digital signal, and sends it to the control unit 150. The control unit 150 is connected to the drive circuit 110, the current measurement circuit 120, the voltage measurement circuit 130, and the LS voltage measurement circuit 140. Based on the received differential digital signals of current measurement, voltage measurement, and LS measurement, it analyzes and obtains the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Based on the current measurement value, voltage measurement value, LS voltage measurement value, and preset calibration coefficients, it obtains the current measurement correction value and voltage measurement correction value. The control unit 150 performs feedback adjustment based on the current measurement correction value and voltage measurement correction value and outputs a control signal to the drive circuit to adjust the current and voltage of the excitation signal. The device under test (DUT) can be a chip under test or other devices that need to receive an excitation signal for testing. The voltage to ground of the low-side voltage line LS refers to the differential voltage between the low-side voltage line LS and the ground terminal, which can be assumed to be 0V. It is understandable that the VI source common mode compensation device in this application can also be regarded as a VI source board.

[0058] Furthermore, the calibration coefficients include current measurement calibration coefficients, voltage measurement calibration coefficients, LS voltage measurement calibration coefficients, voltage measurement common-mode compensation coefficients, and current measurement common-mode compensation coefficients. The control unit 150 corrects the current measurement value MI0 according to the current measurement calibration coefficients to obtain the current measurement value MI1; it corrects the voltage measurement value MV0 according to the voltage measurement calibration coefficients to obtain the voltage measurement value MV1; and it corrects the LS voltage measurement value MLS0 according to the LS voltage measurement calibration coefficients to obtain the LS voltage measurement value MLS1. The control unit 150 also corrects the LS voltage measurement value MLS1 and the voltage measurement value MV1 according to the voltage measurement common-mode compensation coefficients to obtain the voltage measurement correction value MV and the HS terminal voltage correction value MHS, respectively. Finally, it corrects the current measurement value MI1 according to the current measurement common-mode compensation coefficients and the HS terminal voltage correction value MHS to obtain the current measurement correction value MI.

[0059] It is understandable that when performing common-mode compensation correction on the current measurement value MI1, a voltage correction value MHS is introduced at the HS terminal. The HS terminal voltage correction value MHS is the common-mode voltage value. The high-side voltage line HS and the high-side current line HF are shorted to the device under test, and the voltage of the high-side voltage line HS and the voltage of the high-side current line HF are the same. In this embodiment, as... Figure 3 As shown, the calibration coefficients for current measurement are kmi and bmi, for voltage measurement are kmv and bmv, for LS voltage measurement are kls and bls, for voltage measurement common-mode compensation coefficients are kvcom and bvcom, and for current measurement common-mode compensation coefficients are kicom and bicom. Real-time acquired current measurement values ​​are denoted as MI0, current measurement values ​​as MV0, and LS voltage measurement values ​​as MLS0. The common-mode compensation algorithm is as follows:

[0060] The voltage measurement value MV0 is corrected using voltage measurement calibration factors kmv and bmv:

[0061] MV1 = MV0 * kmv + bmv

[0062] The LS voltage measurement value MLS0 is corrected using the LS voltage measurement calibration coefficients kls and bls:

[0063] MLS1 = MLS0 * kls + bls

[0064] The corrected voltage measurement values ​​MV1 and MLS1 are then further corrected using the common-mode compensation coefficients kvcom and bvcom to obtain the corrected voltage measurement values ​​MV1 and MHS terminal voltage correction values:

[0065] MV = MV1 + MLS1 * kvcom + bvcom

[0066] MHS = MV + MLS1

[0067] The current measurement value MI0 is corrected using the current measurement calibration coefficients kmi and bmi:

[0068] MI1 = MI0 * kmi + bmi

[0069] The corrected current measurement value MI1 and the corrected voltage value MHS at the HS terminal are then further corrected using the common-mode compensation coefficients kicom and bicom for current measurement, resulting in the corrected current measurement value MI.

[0070] MI = MI1 + MHS * kicom + bicom

[0071] In summary, the formulas for calculating the voltage measurement correction value MV and the current measurement correction value MI are as follows:

[0072] MV = MV0 * kmv + bmv + (MLS0 * kls + bls)* kvcom + bvcom

[0073] MI = MI0 * kmi + bmi +[ MV0 * kmv + bmv + (MLS0 * kls + bls)*(1+kvcom) + bvcom ] * kicom + bicom

[0074] Among them, the obtained current measurement value is MI0, the current measurement value is MV0, and the LS voltage measurement value is MLS0; kmi and bmi are current measurement calibration coefficients, kmv and bmv are voltage measurement calibration coefficients, kls and bls are LS voltage measurement calibration coefficients, kvcom and bvcom are voltage measurement common-mode compensation coefficients, and kicom and bicom are current measurement common-mode compensation coefficients.

[0075] In addition, the VI source common-mode compensation device also includes a multimeter for detecting the voltage / output current across the load; the calibration coefficient is obtained by calibrating based on the current measurement value, voltage measurement value, LS voltage measurement value detected by the common-mode compensation device under different load conditions, as well as the voltage / output current across the load read by the multimeter.

[0076] The drive circuit 110 receives control signals from the control unit 150 and outputs voltage / current excitation to the device under test (DUT). The current measurement circuit 120 measures the output current of the drive circuit 110 on the high-side current line HF. The voltage measurement circuit 130 detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS. The LS voltage measurement circuit 140 detects the voltage to ground of the low-side voltage line LS. The control unit 150 analyzes the received digital signals and set calibration coefficients to obtain voltage and current measurement correction values. Based on these correction values, a feedback closed-loop control is performed to adjust the output excitation voltage / current of the drive circuit 110. The feedback closed-loop control can employ, but is not limited to, a PID algorithm.

[0077] In one embodiment, the control unit 150 may consist only of a controller that performs calibration operations on the current measurement circuit 120, voltage measurement circuit 130, LS voltage measurement circuit 140, and data collected by a multimeter to determine calibration coefficients. When actually measuring the device under test (DUT), the controller analyzes the digital signals output by the current measurement circuit 120, voltage measurement circuit 130, and LS voltage measurement circuit 140, along with the set calibration coefficients, to obtain the corresponding current measurement correction value and voltage measurement correction value, and then adjusts the excitation signal output by the drive circuit 110 accordingly. In another embodiment, the control unit 150 may also include a controller and a terminal. The controller connects to the drive circuit 110, current measurement circuit 120, voltage measurement circuit 130, LS voltage measurement circuit 140, and the terminal. It uploads the collected data from the current measurement circuit 120, voltage measurement circuit 130, and LS voltage measurement circuit 140 to the terminal. The terminal then combines the data collected by the multimeter to calibrate the current measurement circuit 120, voltage measurement circuit 130, and LS voltage measurement circuit 140, determining the calibration coefficients. The terminal then analyzes and obtains the current measurement correction value and voltage measurement correction value, and sends them to the controller. The controller feeds back the adjustment output control signal to the drive circuit 110, and the drive circuit 110 outputs an excitation signal to the device under test. The controller can be an FPGA, CPU, CPLD, MCU, or other devices. In this embodiment, an FPGA is used. The terminal can be, but is not limited to, various personal computers, laptops, smartphones, tablets, and portable wearable devices. Portable wearable devices can be smartwatches, smart bracelets, head-mounted devices, etc.

[0078] It is understood that the specific structures of the drive circuit 110, current measurement circuit 120, voltage measurement circuit 130, and LS voltage measurement circuit 140 are not unique. In one embodiment, such as Figure 2 As shown, the drive circuit 110 includes a digital-to-analog converter (DAC) and a power amplifier (PA). The DAC is connected to the control unit 150 (specifically connected to the FPGA) and the power amplifier PA. The power amplifier PA is connected to the device under test (DUT) via a high-side current line HF. The DUT is connected to the internal ground of the drive circuit 110 via a low-side current line LF. The DAC receives the digital signal output from the FPGA, converts it into an analog signal, and outputs it to the power amplifier PA. The power amplifier PA increases the power of the analog signal by a preset factor. The increased analog signal outputs an excitation signal to the DUT via the high-side current line HF, and then returns to the ground via the low-side current line LF.

[0079] In one embodiment, continue to refer to Figure 2The current measurement circuit 120 includes a current sampling resistor Rs, follower operational amplifiers U1 and U2, a differential operational amplifier U3, and an analog-to-digital converter (ADC1). The current sampling resistor Rs is connected in series on the high-side current line HF. The non-inverting input of follower operational amplifier U1 is connected to the first terminal of the current sampling resistor Rs. The inverting input of follower operational amplifier U1 is connected to the output of follower operational amplifier U1 and the first input of differential operational amplifier U3. The non-inverting input of follower operational amplifier U2 is connected to the second terminal of the current sampling resistor Rs. The inverting input of follower operational amplifier U2 is connected to the output of follower operational amplifier U2 and the second input of differential operational amplifier U3. The output of differential operational amplifier U3 is connected to the control unit 150 (specifically connected to the FPGA) via the ADC1. The current flowing through the current sampling resistor Rs is measured using the current measurement circuit 120 and converted into a digital quantity, which is then output to the FPGA. Among them, follower operational amplifiers U1 and U2 are used to improve the driving capability of the voltage across the current sampling resistor Rs, and differential operational amplifier U3 is used to perform differential operation on the voltage across the current sampling resistor Rs.

[0080] In one embodiment, such as Figure 2 As shown, the voltage measurement circuit 130 includes follower operational amplifiers U4 and U5, a differential operational amplifier U6, and an analog-to-digital converter (ADC2). The non-inverting input of follower operational amplifier U4 is connected to the high-side voltage line HS, and the inverting input is connected to its output and the first input of the differential operational amplifier U6. The non-inverting input of follower operational amplifier U5 is connected to the low-side voltage line LS, and the inverting input is connected to its output and the second input of the differential operational amplifier U6. The output of the differential operational amplifier U6 is connected to the control unit 150 (specifically connected to the FPGA) via the ADC2. The voltage measurement circuit 130 measures the differential voltage between the high-side voltage line HS and the low-side voltage line LS and converts it into a digital signal, which is then output to the FPGA. Follower operational amplifiers U4 and U5 are used to improve the driving capability of the high-side voltage line HS and the low-side voltage line LS, respectively, while the differential operational amplifier U6 performs differential operations on the voltages of the high-side voltage line HS and the low-side voltage line LS.

[0081] Furthermore, the LS voltage measurement circuit 140 includes a differential operational amplifier U7 and an analog-to-digital converter ADC3. The first input terminal of the differential operational amplifier U7 is connected to the output terminal of the follower operational amplifier U5, and the second input terminal of the differential operational amplifier U7 is connected to the internal ground terminal of the driver circuit 110. The output terminal of the differential operational amplifier U7 is connected to the control unit 150 (specifically connected to the FPGA) through the analog-to-digital converter ADC3. The LS voltage measurement circuit 140 measures the differential voltage between the low-side voltage line LS and ground, and converts it into a digital quantity for output to the FPGA. Specifically, the differential operational amplifier U7 is used to perform a differential operation between the voltage of the low-side voltage line LS and the ground terminal to obtain the differential voltage.

[0082] There is no single way to determine the calibration coefficients. For voltage measurement calibration, the following method is used: (e.g.) Figure 4 As shown, the VI source output Kelvin four-wire connection is used to connect to the load RLoad1. A multimeter is connected across the load RLoad1 to measure the voltage. The load RLoad1 is typically a kiloohm or megaohm resistor. A kiloohm or megaohm resistor differs from an ohm or milliohm resistor by a factor of a thousand, the purpose of which is to simulate no-load or loaded application scenarios.

[0083] Specifically, such as Figure 5 As shown, in step Sa1: the VI source is connected to the load RLoad1, the VI source maintains a constant voltage output of n different voltage excitations, the multimeter reads the voltage MVR1 across the load RLoad1, and the VI source control unit 150 reads the voltage measurement MV0 (that is, the differential voltage is determined in real time according to the voltage measurement differential digital signal output by the voltage measurement circuit 130), and obtains the arrays MVR1[n] and MV0[n] respectively.

[0084] Step Sa2: By combining the arrays MVR1[n] and MV0[n], the voltage measurement calibration coefficients kmv and bmv are calculated through linear fitting of MVR1[n] = MV0[n] * kmv + bmv.

[0085] For current measurement calibration, the following method is used: Figure 6 As shown, the VI source output Kelvin four-wire connection is connected to the load RLoad2. A multimeter is connected in series in the low-end current line HF link to measure the output current. The load RLoad2 is usually a resistor in the ohm or milliohm range.

[0086] Specifically, such as Figure 7As shown, in step Sa3: the VI source is connected to the load RLoad2, the VI source maintains constant current output of m groups of different current excitations, the multimeter reads the output current MIR, and the VI source control unit 150 reads the voltage measurement MI0 (that is, the output current of the drive circuit is determined in real time according to the current measurement differential digital signal output by the current measurement circuit 120), and the arrays MIR2[m] and MI0[m] are obtained respectively.

[0087] Step Sa4: By combining the arrays MIR2[m] and MI0[m], the current measurement calibration coefficients kmi and bmi are calculated through linear fitting of MIR2[m] = MI0[m] * kmi + bmi.

[0088] For LS voltage measurement calibration, the calibration method is as follows: Figure 8 As shown, the VI source output Kelvin four-wire connection is connected to load RLoad3, and load RLoad4 is connected in series in the low-end current line LF link. A multimeter is connected in parallel across load RLoad4 to measure the voltage. Loads RLoad3 and RLoad4 are usually kiloohm level resistors, and the resistance of load RLoad3 is 5 to 10 times the resistance of load RLoad4. Load RLoad3 can also be replaced by load RLoad1.

[0089] In this embodiment, when the VI source is connected to the load RLoad3 and the load RLoad4 is connected in series in the low-end current line LF, the control unit 150 controls the drive circuit 110 to output p groups of different excitation voltages, and determines the LS voltage measurement value MLS0[p] in real time according to the LS measurement digital signal output by the LS voltage measurement circuit 140. The voltmeter measurement value MVR4[p] across the load RLoad4 is read by a multimeter. The control unit 150 performs linear fitting based on the LS voltage measurement value MLS0[p] and the voltmeter measurement value MVR4[p] to calculate the LS voltage measurement calibration coefficient.

[0090] Specifically, such as Figure 9 As shown, in step Sa5: the VI source is connected to the load Rload3, the low-end current line LF is connected in series with the load Rload4, the VI source maintains a constant voltage output of p groups of different voltage excitations, the multimeter reads the voltage across Rload4, and the VI source control unit 150 reads the LS voltage measurement, which can obtain the arrays MVR4[p] and MLS0[p] respectively.

[0091] Step Sa6: By combining the arrays MVR4[p] and MLS0[p] and linearly fitting MVR4[p] = MLS0[p] * kls + bls, the LS voltage measurement calibration coefficients kls and bls are calculated.

[0092] For voltage measurement common-mode compensation calibration, the calibration method is as follows: Figure 10 As shown, the Kelvin four-wire output of source VI is connected to load RLoad3, load RLoad4 is connected in series in the low-end current line LF link, and a multimeter is connected in parallel across load RLoad3 to measure the voltage.

[0093] In this embodiment, when the VI source is connected to the load RLoad3 and the load RLoad4 is connected in series in the low-side current line LF, the control unit 150 controls the drive circuit 110 to output q groups of different excitation voltages. The control unit determines the LS voltage measurement value MLS0[q] in real time based on the LS measurement digital signal output by the LS voltage measurement circuit 140, and determines the voltage measurement value MV0[q] based on the voltage measurement differential digital signal output by the voltage measurement circuit 130. The control unit 150 reads the voltmeter measurement value MVR3[q] across the load RLoad3 using a multimeter. The voltage measurement value MV1[q] is obtained by correcting the voltage measurement value MV0[q] and the voltage measurement calibration coefficient. The LS voltage measurement value MLS0[q] is obtained by correcting the LS voltage measurement value MLS1[q] and the LS voltage measurement calibration coefficient. The voltage measurement common-mode error Mvcom[q] is calculated and determined based on the voltage measurement value MV1[q] and the voltmeter measurement value MVR3[q]. The voltage measurement common-mode error Mvcom[q] and the LS voltage measurement value MLS1[q] are linearly fitted to calculate the voltage measurement common-mode compensation coefficient.

[0094] Specifically, such as Figure 11 As shown, in step Sb1: the VI source is connected to the load Rload3, the low-end current line LF is connected in series with the load Rload4, the VI source maintains a constant voltage output of q different voltages, the multimeter reads the voltage across Rload3, the VI source reads the LS voltage measurement and voltage measurement, and obtains the arrays MVR3[q], MLS0[q], and MV0[q] respectively.

[0095] Step Sb2: Calculate the arrays MLS1[q] and MV1[q] based on the calibration coefficients. Specifically, array MV1[q] is obtained by correcting array MV0[q] and the voltage measurement calibration coefficients, and array MLS1[q] is obtained by correcting array MLS0[q] and the LS voltage measurement calibration coefficients.

[0096] Step Sb3: Calculate the voltage measurement common-mode error Mvcom[q] = MVR3[q] - MV1[q] based on array MVR3[q] and array MV1[q].

[0097] Step Sb4: By combining the arrays Mvcom[q] and MLS1[q] and linearly fitting Mvcom[q] = MLS1[q] *kvcom + bvcom, the common-mode compensation coefficients kvcom and bvcom for voltage measurement are calculated.

[0098] For common-mode compensation calibration of current measurement, the calibration is performed in the following manner: Figure 12 As shown, the VI source output Kelvin four-wire connection is connected to the load RLoad5. A multimeter is connected in series in the low-end current line LF link to measure the current. The load RLoad5 is usually in the tens or hundreds of ohms range.

[0099] In this embodiment, when the VI source is connected to the load RLoad5, the control unit 150 controls the drive circuit 110 to output x sets of different excitation voltages. In real time, it determines the LS voltage measurement value MLS0[x] based on the LS measurement digital signal output by the LS voltage measurement circuit 140, the voltage measurement value MV0[x] based on the voltage measurement differential digital signal output by the voltage measurement circuit 130, and the current measurement value MI0[x] based on the current measurement differential digital signal output by the current measurement circuit 120. It then reads the output ammeter measurement value MIR5[x] of the load RLoad5 using a multimeter. The control unit 150 corrects the voltage measurement value MV0[x] based on the voltage measurement value MV0[x] and the voltage measurement calibration coefficient to obtain the voltage measurement value MV1[x]. The LS voltage measurement value MLS0[x] and the LS voltage measurement calibration coefficient are corrected to obtain the LS voltage measurement value MLS1[x]. The current measurement value MI1[x] is corrected based on the current measurement value MI0[x] and the current measurement calibration coefficient. The HS terminal voltage correction value MHS[x] is calculated and determined based on the voltage measurement value MV1[x], the LS voltage measurement value MLS1[x], and the voltage measurement common-mode compensation coefficient. The current measurement common-mode error Micom[x] is calculated and determined based on the current measurement value MI1[x] and the output ammeter measurement value MIR5[x]. The current measurement common-mode error Micom[x] and the HS terminal voltage correction value MHS[x] are linearly fitted to calculate the current measurement common-mode compensation coefficient.

[0100] Specifically, such as Figure 13 As shown, in step Sc1: the VI source is connected to the load Rload5, the VI source maintains a constant voltage output x groups of different voltage excitations, the multimeter reads the output current, the VI source reads the LS voltage measurement, voltage measurement, and current measurement, and obtains the arrays MIR5[x], MLS0[x], MV0[x], and MI0[x] respectively.

[0101] Step Sc2: Calculate the arrays MHS[x] and MI1[x] based on the calibration coefficients. Specifically, array MV1[x] is obtained by correcting array MV0[x] and the voltage measurement calibration coefficient, array MLS0[x] is obtained by correcting array MLS0[x] and the LS voltage measurement calibration coefficient, and array MI0[x] is obtained by correcting array MI1[x] and the current measurement calibration coefficient. Based on array MV1[x], array MLS1[x], and the voltage measurement common-mode compensation coefficient, array MHS[x] is calculated and determined using the formulas MV = MV1 + MLS1 *kvcom + bvcom and MHS = MV + MLS1.

[0102] Step Sc3: Calculate the common-mode error of current measurement Micom[x] = MIR5[x] - MI1[x] based on arrays MIR5[x] and MI1[x].

[0103] Step Sc4: By combining the arrays Micom[x] and MHS[x] and linearly fitting Micom[x] = MHS[x] * kicom + bicom, the common-mode compensation coefficients kicom and bicom for current measurement are calculated.

[0104] The aforementioned VI source common-mode compensation device improves the measurement link by adding an LS voltage measurement circuit to sample the voltage to ground of the low-end voltage line LS, and performs common-mode compensation calculations using calibrated compensation coefficients. This achieves the goal of eliminating common-mode errors and improving the voltage / current measurement accuracy of the VI source.

[0105] In one embodiment, a common-mode compensation method for a VI source is also provided, applied to a control unit in a VI source common-mode compensation device. The common-mode compensation method includes:

[0106] Step S11: Analyze the received differential digital signals for current measurement, voltage measurement, and LS measurement to obtain the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Specifically, the current measurement circuit detects the output current of the drive circuit and converts it into a differential digital signal for current measurement, which is then sent to the control unit. The voltage measurement circuit detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS and converts it into a differential digital signal for voltage measurement, which is then sent to the control unit. The LS voltage measurement circuit detects the voltage to ground of the low-side voltage line LS and converts it into a digital signal for LS measurement, which is then sent to the control unit.

[0107] Step S12: Based on the current measurement value, voltage measurement value, LS voltage measurement, and preset calibration coefficient, obtain the current measurement correction value and voltage measurement correction value.

[0108] Step S13: Based on the current measurement correction value and the voltage measurement correction value, perform feedback adjustment and output control signal to the drive circuit; wherein, the drive circuit is connected to the device under test through the high-side current line HF, and outputs excitation signal to the device under test according to the control signal sent by the control unit.

[0109] In one embodiment, the method further includes step S10: calibrating based on the current measurement value, voltage measurement value, LS voltage measurement value detected under different load conditions, and the voltage / output current across the load read by the multimeter, and determining the calibration coefficient.

[0110] In one embodiment, the calibration coefficients include LS voltage measurement calibration coefficients; determining the calibration coefficients includes:

[0111] Step S101: When the load RLoad3 is connected to the VI source and the load RLoad4 is connected in series in the low-end current line LF, the control drive circuit outputs p groups of different excitation voltages, and determines the LS voltage measurement value MLS0[p] in real time according to the LS measurement digital signal output by the LS voltage measurement circuit, and reads the voltage meter measurement value MVR4[p] across the load RLoad4 using a multimeter.

[0112] Step S102: Perform linear fitting based on the LS voltage measurement value MLS0[p] and the voltmeter measurement value MVR4[p] to calculate the LS voltage measurement calibration coefficient.

[0113] In one embodiment, the calibration coefficients further include voltage measurement common-mode compensation coefficients; determining the calibration coefficients further includes:

[0114] Step S103: When the load RLoad3 is connected to the VI source and the load RLoad4 is connected in series in the low-end current line LF, the control drive circuit outputs q different excitation voltages, and determines the LS voltage measurement value MLS0[q] in real time according to the LS measurement digital signal output by the LS voltage measurement circuit, determines the voltage measurement value MV0[q] according to the voltage measurement differential digital signal output by the voltage measurement circuit, and reads the voltage meter measurement value MVR3[q] across the load RLoad3 using a multimeter.

[0115] Step S104: Based on the voltage measurement value MV0[q] and the voltage measurement calibration coefficient, the voltage measurement value MV1[q] is obtained by correction. Based on the LS voltage measurement value MLS0[q] and the LS voltage measurement calibration coefficient, the LS voltage measurement value MLS1[q] is obtained by correction. The voltage measurement common-mode error Mvcom[q] is calculated and determined according to the voltage measurement value MV1[q] and the voltmeter measurement value MVR3[q]. The voltage measurement common-mode error Mvcom[q] and the LS voltage measurement value MLS1[q] are linearly fitted to calculate the voltage measurement common-mode compensation coefficient.

[0116] In one embodiment, the calibration coefficients further include a current measurement common-mode compensation coefficient; determining the calibration coefficients further includes:

[0117] Step S105: When the VI source is connected to the load RLoad5, the control drive circuit outputs x sets of different excitation voltages. The LS voltage measurement value MLS0[x] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage measurement value MV0[x] is determined according to the voltage measurement differential digital signal output by the voltage measurement circuit. The current measurement value MI0[x] is determined according to the current measurement differential digital signal output by the current measurement circuit. The output ammeter value MIR5[x] of the load RLoad5 is read by a multimeter.

[0118] Step S106: Based on the voltage measurement value MV0[x] and the voltage measurement calibration coefficient, the voltage measurement value MV1[x] is obtained by correction. Based on the LS voltage measurement value MLS0[x] and the LS voltage measurement calibration coefficient, the LS voltage measurement value MLS1[x] is obtained by correction. Based on the current measurement value MI0[x] and the current measurement calibration coefficient, the current measurement value MI1[x] is obtained by correction. Based on the voltage measurement value MV1[x], the LS voltage measurement value MLS1[x] and the voltage measurement common-mode compensation coefficient, the HS terminal voltage correction value MHS[x] is calculated and determined. Based on the current measurement value MI1[x] and the output ammeter measurement value MIR5[x], the current measurement common-mode error Micom[x] is calculated and determined. Based on the current measurement common-mode error Micom[x] and the HS terminal voltage correction value MHS[x], the current measurement common-mode compensation coefficient is calculated by linear fitting.

[0119] In one embodiment, the calibration coefficients include current measurement calibration coefficients, voltage measurement calibration coefficients, LS voltage measurement calibration coefficients, voltage measurement common-mode compensation coefficients, and current measurement common-mode compensation coefficients; step S12 further includes:

[0120] Step S121: Correct the current measurement value MI0 according to the current measurement calibration coefficient to obtain the current measurement value MI1; correct the voltage measurement value MV0 according to the voltage measurement calibration coefficient to obtain the voltage measurement value MV1; correct the LS voltage measurement value MLS0 according to the LS voltage measurement calibration coefficient to obtain the LS voltage measurement value MLS1.

[0121] Step S122: Correct the LS voltage measurement value MLS1 and the voltage measurement value MV1 according to the voltage measurement common mode compensation coefficient to obtain the voltage measurement correction value MV and the HS terminal voltage correction value MHS respectively. Correct the current measurement value MI1 according to the current measurement common mode compensation coefficient and the HS terminal voltage correction value MHS to obtain the current measurement correction value MI.

[0122] It is understood that the specific embodiments of the VI source common mode compensation method have been explained in detail in the above-mentioned VI source common mode compensation device, and will not be repeated here.

[0123] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0124] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A VI source common-mode compensation device, characterized in that, include: The driving circuit is connected to the device under test (DUT) via the high-end current line HF, and outputs an excitation signal to the DUT according to the control signal sent by the control unit. A current measurement circuit is connected to the drive circuit, detects the output current of the drive circuit, converts it into a current measurement differential digital signal, and sends it to the control unit. The voltage measurement circuit is connected to the device under test through a high-side voltage line HS and a low-side voltage line LS. It detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS, converts it into a voltage measurement differential digital signal, and sends it to the control unit. The LS voltage measurement circuit, connected to the voltage measurement circuit, detects the voltage to ground of the low-end voltage line LS, converts it into an LS measurement digital signal and sends it to the control unit; The control unit is connected to the drive circuit, the current measurement circuit, the voltage measurement circuit, and the LS voltage measurement circuit. It analyzes the received differential digital signals for current measurement, voltage measurement, and LS measurement to obtain the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Based on the current measurement value, voltage measurement value, LS voltage measurement value, and a preset calibration coefficient, it analyzes and obtains the current measurement correction value and voltage measurement correction value. The control unit performs feedback adjustment based on the current measurement correction value and voltage measurement correction value, and outputs a control signal to the drive circuit.

2. The VI source common-mode compensation device according to claim 1, characterized in that, It also includes a multimeter for detecting the voltage / output current across the load; the calibration coefficient is obtained by calibrating based on the current measurement value, voltage measurement value, LS voltage measurement value detected by the common mode compensation device under different load conditions, and the voltage / output current across the load read by the multimeter.

3. The VI source common-mode compensation device according to claim 1, characterized in that, The calibration coefficients include current measurement calibration coefficients, voltage measurement calibration coefficients, LS voltage measurement calibration coefficients, voltage measurement common-mode compensation coefficients, and current measurement common-mode compensation coefficients. The control unit corrects the current measurement value MI0 according to the current measurement calibration coefficient to obtain the current measurement value MI1, corrects the voltage measurement value MV0 according to the voltage measurement calibration coefficient to obtain the voltage measurement value MV1, and corrects the LS voltage measurement value MLS0 according to the LS voltage measurement calibration coefficient to obtain the LS voltage measurement value MLS1. The control unit corrects the LS voltage measurement value MLS1 and the voltage measurement value MV1 according to the voltage measurement common-mode compensation coefficient, to obtain the voltage measurement correction value MV and the HS terminal voltage correction value MHS respectively. The control unit corrects the current measurement value MI1 according to the current measurement common-mode compensation coefficient and the HS terminal voltage correction value MHS, to obtain the current measurement correction value MI.

4. The VI source common-mode compensation device according to claim 3, characterized in that, The formula for calculating the voltage measurement correction value MV is: MV = MV0 * kmv + bmv + (MLS0 * kls + bls)* kvcom + bvcom Where kmv and bmv are voltage measurement calibration coefficients, kls and bls are LS voltage measurement calibration coefficients, and kvcom and bvcom are voltage measurement common-mode compensation coefficients.

5. The VI source common-mode compensation device according to claim 3, characterized in that, The formula for calculating the current measurement correction value MI is: MI = MI0 * kmi + bmi +[ MV0 * kmv + bmv + (MLS0 * kls + bls)*(1+ kvcom) +bvcom ] * kicom + bicom Where kmi and bmi are current measurement calibration coefficients, kmv and bmv are voltage measurement calibration coefficients, kls and bls are LS voltage measurement calibration coefficients, kvcom and bvcom are voltage measurement common-mode compensation coefficients, and kicom and bicom are current measurement common-mode compensation coefficients.

6. The VI source common-mode compensation device according to any one of claims 1 to 5, characterized in that, The driving circuit includes a digital-to-analog converter and a power amplifier. The digital-to-analog converter is connected to the control unit and the power amplifier. The power amplifier is connected to the device under test (DUT) via a high-side current line HF. The DUT is connected to the internal ground terminal of the driving circuit via a low-side current line LF.

7. The VI source common-mode compensation device according to any one of claims 1 to 5, characterized in that, The current measurement circuit includes a current sampling resistor, a follower operational amplifier U1, a follower operational amplifier U2, a differential operational amplifier U3, and an analog-to-digital converter (ADC1). The current sampling resistor is connected in series on the high-side current line HF. The non-inverting input of the follower operational amplifier U1 is connected to the first terminal of the current sampling resistor. The inverting input of the follower operational amplifier U1 is connected to the output of the follower operational amplifier U1 and the first input of the differential operational amplifier U3. The non-inverting input of the follower operational amplifier U2 is connected to the second terminal of the current sampling resistor. The inverting input of the follower operational amplifier U2 is connected to the output of the follower operational amplifier U2 and the second input of the differential operational amplifier U3. The output of the differential operational amplifier U3 is connected to the control unit through the ADC1.

8. The VI source common-mode compensation device according to any one of claims 1 to 5, characterized in that, The voltage measurement circuit includes a follower operational amplifier U4, a follower operational amplifier U5, a differential operational amplifier U6, and an analog-to-digital converter ADC2. The non-inverting input of the follower operational amplifier U4 is connected to the high-side voltage line HS. The inverting input of the follower operational amplifier U4 is connected to the output of the follower operational amplifier U4 and the first input of the differential operational amplifier U6. The non-inverting input of the follower operational amplifier U5 is connected to the low-side voltage line LS. The inverting input of the follower operational amplifier U5 is connected to the output of the follower operational amplifier U5 and the second input of the differential operational amplifier U6. The output of the differential operational amplifier U6 is connected to the control unit through the analog-to-digital converter ADC2.

9. The VI source common-mode compensation device according to claim 8, characterized in that, The LS voltage measurement circuit includes a differential operational amplifier U7 and an analog-to-digital converter ADC3. The first input terminal of the differential operational amplifier U7 is connected to the output terminal of the follower operational amplifier U5, the second input terminal of the differential operational amplifier U7 is connected to the internal ground terminal of the drive circuit, and the output terminal of the differential operational amplifier U7 is connected to the control unit through the analog-to-digital converter ADC3.

10. A common-mode compensation method for VI sources, characterized in that, The control unit used in the VI source common mode compensation device includes the following common mode compensation methods: The received differential digital signals for current measurement, voltage measurement, and LS measurement are analyzed to obtain the current measurement value, voltage measurement value, and LS voltage measurement value, respectively. Specifically, the current measurement circuit detects the output current of the drive circuit and converts it into a differential digital signal for current measurement, which is then sent to the control unit. The voltage measurement circuit detects the differential voltage between the high-side voltage line HS and the low-side voltage line LS and converts it into a differential digital signal for voltage measurement, which is then sent to the control unit. The LS voltage measurement circuit detects the voltage to ground of the low-side voltage line LS and converts it into a digital signal for LS measurement, which is then sent to the control unit. The current measurement correction value and the voltage measurement correction value are obtained by analyzing the current measurement value, the voltage measurement value, the LS voltage measurement value, and the preset calibration coefficient; Based on the current measurement correction value and the voltage measurement correction value, a feedback adjustment is performed to output a control signal to the drive circuit; wherein, the drive circuit is connected to the device under test through the high-side current line HF, and outputs an excitation signal to the device under test according to the control signal sent by the control unit.

11. The method according to claim 10, characterized in that, Also includes: The calibration coefficient is determined by calibrating based on the current measurement, voltage measurement, LS voltage measurement, and the voltage / output current across the load read by the multimeter under different load conditions.

12. The method according to claim 11, characterized in that, The calibration coefficients include current measurement calibration coefficients, voltage measurement calibration coefficients, LS voltage measurement calibration coefficients, voltage measurement common-mode compensation coefficients, and current measurement common-mode compensation coefficients; the process of obtaining current measurement correction values ​​and voltage measurement correction values ​​based on the current measurement value, the voltage measurement value, the LS voltage measurement, and the preset calibration coefficients includes: The current measurement value MI0 is corrected according to the current measurement calibration coefficient to obtain the current measurement value MI1; the voltage measurement value MV0 is corrected according to the voltage measurement calibration coefficient to obtain the voltage measurement value MV1; and the LS voltage measurement value MLS0 is corrected according to the LS voltage measurement calibration coefficient to obtain the LS voltage measurement value MLS1. The voltage measurement values ​​MLS1 and MV1 are corrected according to the common-mode compensation coefficient of the voltage measurement to obtain the voltage measurement correction value MV and the HS terminal voltage correction value MHS, respectively. The current measurement value MI1 is corrected according to the common-mode compensation coefficient of the current measurement and the HS terminal voltage correction value MHS to obtain the current measurement correction value MI.

13. The method according to claim 11, characterized in that, The calibration coefficients include LS voltage measurement calibration coefficients; determining the calibration coefficients includes: When the VI source is connected to the load RLoad3 and the load RLoad4 is connected in series in the low-end current line LF, the drive circuit is controlled to output p groups of different excitation voltages. The LS voltage measurement value MLS0[p] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage meter measurement value MVR4[p] across the load RLoad4 is read by a multimeter. The calibration coefficient for LS voltage measurement is calculated by performing linear fitting based on the LS voltage measurement value MLS0[p] and the voltmeter measurement value MVR4[p].

14. The method according to claim 13, characterized in that, The calibration coefficients also include voltage measurement common-mode compensation coefficients; determining the calibration coefficients also includes: When the VI source is connected to the load RLoad3 and the load RLoad4 is connected in series in the low-end current line LF, the drive circuit is controlled to output q different excitation voltages. The LS voltage measurement value MLS0[q] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage measurement value MV0[q] is determined according to the voltage measurement differential digital signal output by the voltage measurement circuit. The voltage meter measurement value MVR3[q] at both ends of the load RLoad3 is read by a multimeter. The voltage measurement value MV1[q] is obtained by correcting the voltage measurement value MV0[q] and the voltage measurement calibration coefficient. The LS voltage measurement value MLS0[q] is obtained by correcting the LS voltage measurement value MLS1[q] and the LS voltage measurement calibration coefficient. The voltage measurement common-mode error Mvcom[q] is calculated and determined based on the voltage measurement value MV1[q] and the voltmeter measurement value MVR3[q]. The voltage measurement common-mode error Mvcom[q] and the LS voltage measurement value MLS1[q] are linearly fitted to calculate the voltage measurement common-mode compensation coefficient.

15. The method according to claim 14, characterized in that, The calibration coefficients also include current measurement common-mode compensation coefficients; determining the calibration coefficients also includes: When the VI source is connected to the load RLoad5, the drive circuit is controlled to output x different excitation voltages. The LS voltage measurement value MLS0[x] is determined in real time according to the LS measurement digital signal output by the LS voltage measurement circuit. The voltage measurement value MV0[x] is determined according to the voltage measurement differential digital signal output by the voltage measurement circuit. The current measurement value MI0[x] is determined according to the current measurement differential digital signal output by the current measurement circuit. The output ammeter measurement value MIR5[x] of the load RLoad5 is read by a multimeter. The voltage measurement value MV1[x] is obtained by correcting the voltage measurement value MV0[x] and the voltage measurement calibration coefficient. The LS voltage measurement value MLS0[x] and the LS voltage measurement calibration coefficient are also corrected to obtain the LS voltage measurement value MLS1[x]. The current measurement value MI0[x] and the current measurement calibration coefficient are also corrected to obtain the current measurement value MI1[x]. The HS terminal voltage correction value MHS[x] is calculated and determined based on the voltage measurement value MV1[x], the LS voltage measurement value MLS1[x], and the voltage measurement common-mode compensation coefficient. The current measurement common-mode error Micom[x] is calculated and determined based on the current measurement value MI1[x] and the output ammeter measurement value MIR5[x]. The current measurement common-mode error Micom[x] and the HS terminal voltage correction value MHS[x] are linearly fitted to obtain the current measurement common-mode compensation coefficient.

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