Digital differential sampling power supply device and calibration method of current measuring unit

Abstract

The invention relates to a digital differential sampling power supply device and a calibration method of a current measurement unit, a driving unit is connected to a to-be-measured device through a high-end current line HF and outputs an excitation signal to the to-be-measured device, and the to-be-measured device is connected to an internal grounding end of the driving unit through a low-end current line LF. The current sampling resistor is connected in series with a high-end current line HF, and the current measuring unit detects voltage to ground at the two ends of the current sampling resistor, converts the voltage to ground to obtain a first digital signal and a second digital signal and transmits the signals to the control unit. And the control unit analyzes according to the received first digital signal and the second digital signal to obtain a measurement current, performs feedback adjustment according to the measurement current, and outputs a control signal to the driving unit to adjust the current of the excitation signal. The current measuring unit detects the voltage to ground at the two ends of the current sampling resistor and calculates and measures the current after the voltage to ground is converted into digital quantity, so that the error of current measurement caused by common-mode voltage can be effectively reduced, and the measurement precision is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor testing, in particular to a digital differential sampling power supply device and a current measurement unit calibration method. BACKGROUND

[0002] In integrated circuit testing, a voltage current source (VI source) is needed to stimulate the signal and measure the voltage and current of the device under test (DUT). In order to improve the output voltage and test voltage accuracy, the VI source adopts a four-wire Kelvin connection mode, which includes a high-end current line (HF), a high-end voltage line (HS), a low-end current line (LF), and a low-end voltage line (LS). The current is output (or input) from the high-end current line HF and flows back (or out) from the low-end current line LF. The voltage measurement takes the difference between the high-end voltage line HS and the low-end voltage line LS as the voltage difference on the DUT. The high-impedance input terminals inside the HS and LS are the same as the voltage of the near and far ends of the signal.

[0003] However, the VI source adopts a four-wire Kelvin connection mode. When calibrating the current and measuring the current of the DUT, the common-mode rejection ratio of the current sampling circuit is limited due to the use of hardware differential measurement, which causes the common-mode voltage to affect the voltage / current measurement results, resulting in low current measurement accuracy. Especially in the high voltage output scenario of the VI source, the measurement error caused by the common-mode voltage is particularly obvious. SUMMARY

[0004] Therefore, it is necessary to provide a digital differential sampling power supply device and a current measurement unit calibration method that can improve measurement accuracy to solve the above problems.

[0005] The first aspect of the present application provides a digital differential sampling power supply device, comprising:

[0006] A driving unit is connected to a device under test through a high-end current line HF and outputs an excitation signal to the device under test. The device under test is connected to the internal ground terminal of the driving unit through a low-end current line LF.

[0007] A current sampling resistor is connected in series to the high-end current line HF.

[0008] A current measurement unit is connected to both ends of the current sampling resistor and detects the voltage to ground at both ends of the current sampling resistor to obtain first and second digital signals and transmit them to a control unit.

[0009] The control unit is connected to the driving unit and the current measuring unit, and obtains a measured current according to the first digital signal and the second digital signal, and performs feedback adjustment according to the measured current, and outputs a control signal to the driving unit to adjust the current of the excitation signal.

[0010] In one embodiment, the control unit determines corresponding sampling machine measured values according to the first digital signal and the second digital signal output by the current measuring unit, and calculates a measured current according to the sampling machine measured values and a set current calibration parameter.

[0011] In one embodiment, the power supply device further comprises a multimeter, which is used to detect a voltmeter measured value of a ground voltage between the two ends of the current sampling resistor, and detect a current flowing through the current sampling resistor.

[0012] When the load is empty, the control unit controls the driving unit to output a plurality of groups of different excitation voltages, respectively determines sampling machine measured values in real time according to the first digital signal and the second digital signal output by the current measuring unit, respectively reads voltmeter measured values of a ground voltage between the two ends of the current sampling resistor through the multimeter, performs linear fitting based on the voltmeter measured value of the ground voltage at the first end of the current sampling resistor and the corresponding sampling machine measured value measured in each group when the load is empty, and performs linear fitting based on the voltmeter measured value of the ground voltage at the second end of the current sampling resistor and the corresponding sampling machine measured value measured in each group when the load is empty, to determine a current machine measured value expression.

[0013] When the load is loaded, the control unit controls the driving unit to output a plurality of groups of different excitation currents, respectively determines corresponding sampling machine measured values in real time according to the first digital signal and the second digital signal output by the current measuring unit, reads ammeter measured values of the current flowing through the current sampling resistor through the multimeter, calculates a current machine measured value of each group based on the sampling machine measured value of each group and the current machine measured value expression, and performs linear fitting according to the current machine measured value of each group and the ammeter measured value measured in each group, to determine a current calibration parameter.

[0014] In one embodiment, the current measuring unit comprises a follower operational amplifier U1, a follower operational amplifier U2, a differential operational amplifier U3, a differential operational amplifier U4, an analog-to-digital converter ADC1, and an analog-to-digital converter ADC2.

[0015] The non-inverting input of the follower operational amplifier U1 is connected to the first end 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, the output of the follower operational amplifier U1 is connected to the first input of the differential operational amplifier U3, the second input of the differential operational amplifier U3 is connected to the ground, and the output of the differential operational amplifier U3 is connected to the analog-to-digital converter ADC1, and the analog-to-digital converter ADC1 is connected to the control unit.

[0016] The non-inverting input of the follower operational amplifier U2 is connected to the second end 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, the output of the follower operational amplifier U2 is connected to the first input of the differential operational amplifier U4, the second input of the differential operational amplifier U4 is connected to the ground, and the output of the differential operational amplifier U4 is connected to the analog-to-digital converter ADC2, and the analog-to-digital converter ADC2 is connected to the control unit.

[0017] In one embodiment, the calculation formula of the measured current is:

[0018] MI=kMI*[(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs+bMI

[0019] Wherein, MI is the measured current, kMI, bMI, kRsH, bRsH, kRsL, bRsL are current calibration parameters, VFB_RsH and VFB_RsL are the sampling measured values of the analog-to-digital converter ADC1 and the analog-to-digital converter ADC2 respectively; Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, and Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located; VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the ground voltage measured values of the first end and the second end of the current sampling resistor respectively.

[0020] In one embodiment, the power supply device further comprises:

[0021] A HS voltage measurement unit connected to the device under test through a high-side voltage line HS, detecting the ground voltage of the high-side voltage line HS, and converting to obtain a HS digital signal transmitted to the control unit;

[0022] A LS voltage measurement unit connected to the device under test through a low-side voltage line LS, detecting the ground voltage of the low-side voltage line LS, and converting to obtain a LS digital signal transmitted to the control unit;

[0023] The control unit is also connected to the HS voltage measurement unit and the LS voltage measurement unit, and the control unit analyzes the measured voltage according to the received HS digital signal and LS digital signal, and performs feedback adjustment according to the measured voltage, and outputs a control signal to the driving unit to adjust the voltage of the excitation signal.

[0024] In one embodiment, the control unit determines the HS sampler measured value and the LS sampler measured value according to the HS digital signal and the LS digital signal output by the HS voltage measurement unit and the LS voltage measurement unit respectively, and calculates the measured voltage according to the HS sampler measured value, the LS sampler measured value and the set voltage calibration parameter.

[0025] In one embodiment, the multimeter is also used to detect the voltmeter measured value of the high-end voltage line HS and the voltmeter measured value of the low-end voltage line LS respectively.

[0026] When loaded, the control unit controls the driving unit to output a plurality of different excitation currents, and real-time obtains the HS sampler measured value and the LS sampler measured value respectively, and the multimeter reads the HS voltmeter measured value and the LS voltmeter measured value respectively, and determines the voltage calibration parameter based on the linear fitting of each group of HS sampler measured value and HS voltmeter measured value, and the linear fitting of each group of LS sampler measured value and LS voltmeter measured value.

[0027] In one embodiment, the HS voltage measurement unit includes a follower operational amplifier U5, a differential operational amplifier U6 and an analog-to-digital converter ADC3, the non-inverting input terminal of the follower operational amplifier U5 is connected to the high-end voltage line HS, the inverting input terminal of the follower operational amplifier U5 is connected to the output terminal of the follower operational amplifier U5, the output terminal of the follower operational amplifier U5 is connected to the first input terminal of the differential operational amplifier U6, the second input terminal of the differential operational amplifier U6 is connected to the ground terminal, the output terminal of the differential operational amplifier U6 is connected to the analog-to-digital converter ADC3, and the analog-to-digital converter ADC3 is connected to the control unit.

[0028] The LS voltage measurement unit includes a follower operational amplifier U7, a differential operational amplifier U8 and an analog-to-digital converter ADC4, the non-inverting input terminal of the follower operational amplifier U7 is connected to the low-end voltage line LS, the inverting input terminal of the follower operational amplifier U7 is connected to the output terminal of the follower operational amplifier U7, the output terminal of the follower operational amplifier U7 is connected to the first input terminal of the differential operational amplifier U8, the second input terminal of the differential operational amplifier U8 is connected to the ground terminal, the output terminal of the differential operational amplifier U8 is connected to the analog-to-digital converter ADC4, and the analog-to-digital converter ADC4 is connected to the control unit.

[0029] In one embodiment, the calculation formula of the measured voltage is:

[0030] MV = (VFB_HS*Gain3*kHS+bHS)-(VFB_LS*Gain4*kLS+bLS)

[0031] wherein MV is the measured voltage, kHS, bHS, kLS, bLS are voltage calibration parameters, VFB_HS is the HS sampling measured value of an analog-to-digital converter ADC3, VFB_LS is the LS sampling measured value of an analog-to-digital converter ADC4; Gain3 is the hardware gain of the link where the analog-to-digital converter ADC3 is located, Gain4 is the hardware gain of the link where the analog-to-digital converter ADC4 is located; VFB_HS*Gain3*kHS+bHS and VFB_LS*Gain4*kLS+bLS are respectively the HS ground voltage measured value and the LS ground voltage measured value.

[0032] The second aspect of the present application provides a calibration method of a current measurement unit, applied to a control unit, a digital differential sampling power supply device including a driving unit, a current measurement unit, a current sampling resistor and a control unit, the current measurement unit being connected to both ends of the current sampling resistor, detecting the ground voltage at both ends of the current sampling resistor respectively, and converting to obtain a first digital signal and a second digital signal to be transmitted to the control unit; the driving unit is connected to a device to be measured through a high-end current line HF, and the device to be measured is connected to the internal ground end of the driving unit through a low-end current line LF; the current sampling resistor is connected in series at both ends of the high-end current line HF; the method comprises:

[0033] The measured current is calculated based on the sampling measured value and the set current calibration parameters, wherein the sampling measured value is determined by the control unit according to the first digital signal and the second digital signal output by the current measurement unit.

[0034] In one embodiment, a multimeter is used to detect the ground voltage meter value at both ends of the current sampling resistor and to detect the current flowing through the current sampling resistor; the determination of the set current calibration parameters comprises:

[0035] When the control unit controls the driving unit to output a plurality of different excitation voltages, the sampling measured value is determined in real time according to the first digital signal and the second digital signal output by the current measurement unit, the ground voltage meter value at both ends of the current sampling resistor is read by the multimeter, the linear fitting is performed based on the ground voltage meter value at the first end of the current sampling resistor and the corresponding sampling measured value measured in each group under no load, and the linear fitting is performed based on the ground voltage meter value at the second end of the current sampling resistor and the corresponding sampling measured value measured in each group under no load, to determine the current measured value expression;

[0036] The control unit controls the driving unit to output a plurality of groups of different excitation currents when loaded, respectively determines corresponding sampling machine measured values in real time according to the first digital signal and the second digital signal output by the current measuring unit, reads the ammeter measured value of the current flowing through the current sampling resistor by the multimeter, calculates the current machine measured value of each group based on each group of sampling machine measured values and the current machine measured value expression when loaded, and performs linear fitting according to the current machine measured value of each group and the ammeter measured value measured by each group to determine the current calibration parameter.

[0037] In one of the embodiments, the current machine measured value expression is determined by performing linear fitting on the ground voltage meter measured value of the first end of the current sampling resistor and the corresponding sampling machine measured value when unloaded, and performing linear fitting on the ground voltage meter measured value of the second end of the current sampling resistor and the corresponding sampling machine measured value when unloaded, and the current machine measured value expression includes:

[0038] The ground voltage machine measured value of the first end of the current sampling resistor and the ground voltage meter measured value are monotonically linearly fitted to obtain the current calibration parameters kRsH and bRsH when unloaded.

[0039] The ground voltage machine measured value of the second end of the current sampling resistor and the ground voltage meter measured value are monotonically linearly fitted to obtain the current calibration parameters kRsL and bRsL when unloaded.

[0040] The current machine measured value expression is:

[0041] MI machine measured value = [(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs

[0042] Wherein, VFB_RsH and VFB_RsL are sampling machine measured values of the analog-to-digital converter ADC1 and the analog-to-digital converter ADC2 respectively, Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located; VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the ground voltage machine measured values of the first end and the second end of the current sampling resistor respectively.

[0043] In one of the embodiments, the current calibration parameter is determined by performing linear fitting on the current machine measured value of each group and the ammeter measured value measured by each group, and the current calibration parameter includes:

[0044] The current machine measured value of each group and the ammeter measured value measured by each group are monotonically linearly fitted to obtain the current calibration parameters kMI and bMI.

[0045] The calculation formula of the measured current MI is:

[0046] MI=kMI*[(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs+bMI.

[0047] The calibration method of the digital differential sampling power supply device and the current measurement unit, the driving unit is connected to the device to be measured through the high-end current line HF, and outputs the excitation signal to the device to be measured. The device to be measured is connected to the internal ground of the driving unit through the low-end current line LF. The current sampling resistor is connected in series on the high-end current line HF. The current measurement unit detects the voltage between the current sampling resistor and the ground, converts the first digital signal and the second digital signal to the control unit. The control unit analyzes the measured current according to the received first digital signal and second digital signal, and adjusts the current of the excitation signal according to the measured current. The control unit outputs the control signal to the driving unit. By detecting the voltage between the current sampling resistor and the ground through the current measurement unit, and converting the digital quantity to calculate the measured current, the error caused by the common-mode voltage to the current measurement can be effectively reduced, and the current measurement accuracy is improved. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 It is a structural block diagram of the digital differential sampling power supply device in one embodiment.

[0049] Figure 2 It is a structural schematic diagram of the digital differential sampling power supply device in one embodiment.

[0050] Figure 3 It is a calibration flowchart of the current measurement unit in one embodiment.

[0051] Figure 4 It is a calibration flowchart of the HS voltage measurement unit and the LS voltage measurement unit in one embodiment. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present 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, high-side current sampling is used. Current measurement is significantly affected by common-mode voltage, while voltage measurement is relatively less affected. During current calibration, a resistive load in the ohmic or milliohm range is typically used. The HF (high-side current) is grounded through the load resistor and LF (low-side current). The potential of the sampling resistor closest to HF is close to 0, meaning current sampling is calibrated under conditions where the common-mode voltage is close to 0. However, during normal operation, the HF voltage will rise to varying degrees depending on the application scenario, mainly due to the voltage drop across the load resistor. The measurement error caused by the common-mode voltage is particularly significant in high-voltage scenarios.

[0056] Therefore, this application provides a digital differential sampling power supply device, which can specifically be a VI source, using the Kelvin four-wire method for output. For example... Figure 1As shown, the digital differential sampling power supply device includes a driving unit 110, a current sampling resistor (not shown), a current measurement unit 120 and a control unit 130. The driving unit 110 is connected to a device under test (DUT) through a high-end current line (HF) and outputs an excitation signal to the device under test (DUT) to apply a voltage / current excitation to the device under test (DUT). The device under test (DUT) is connected to an internal ground of the driving unit 110 through a low-end current line (LF), and the current sampling resistor is connected in series to the high-end current line (HF). The current measurement unit 120 is connected to both ends of the current sampling resistor and detects the voltage of both ends of the current sampling resistor with respect to the ground to convert the first digital signal and the second digital signal to the control unit 130. The control unit 130 is connected to the driving unit 110 and the current measurement unit 120, analyzes the measured current according to the received first digital signal and second digital signal, performs feedback adjustment according to the measured current, and outputs a control signal to the driving unit 110 to adjust the current 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. Figure 2 As shown, the current sampling resistor R S is connected in series to the high-end current line (HF). The current measurement unit 120 detects the voltage of both ends of the current sampling resistor R S with respect to the ground, converts the digital quantity to calculate the measured current, which can effectively reduce the error caused by the common-mode voltage of the hardware differential measurement on the current measurement and improve the current measurement accuracy.

[0057] It can be understood that the voltage of both ends of the current sampling resistor R S with respect to the ground refers to the voltage of the first end of the current sampling resistor R S with respect to the ground, and the voltage of the second end of the current sampling resistor R S with respect to the ground. The ground voltage is 0V by default.

[0058] In an example, the ground in the present application can be the same common ground, i.e., the internal ground of the driving unit.

[0059] Referring to Figure 1 and Figure 2The power supply device further comprises a HS voltage measurement unit 140 and a LS voltage measurement unit 150. The HS voltage measurement unit 140 is connected to the DUT through the high-side voltage line HS, detects the voltage of the high-side voltage line HS relative to the ground, and converts the voltage into a HS digital signal and sends the HS digital signal to the control unit 130. The LS voltage measurement unit 150 is connected to the DUT through the low-side voltage line LS, detects the voltage of the low-side voltage line LS relative to the ground, and converts the voltage into a LS digital signal and sends the LS digital signal to the control unit 130. The control unit 130 is further connected to the HS voltage measurement unit 140 and the LS voltage measurement unit 150. The control unit 130 analyzes the measurement voltage according to the received HS digital signal and LS digital signal, performs feedback adjustment according to the measurement voltage, and outputs a control signal to the driving unit 110 to adjust the voltage of the excitation signal. The HS voltage measurement unit 140 and the LS voltage measurement unit 150 detect the voltage of the high-side voltage line HS relative to the ground and the voltage of the low-side voltage line LS relative to the ground, respectively, convert the voltages into digital quantities, calculate the measurement voltage, reduce the error caused by the common-mode voltage to the voltage measurement, and further improve the voltage measurement accuracy.

[0060] It can be understood that the voltage of the high-side voltage line HS relative to the ground and the voltage of the low-side voltage line LS relative to the ground refer to the voltage relative to the same ground. The voltage of the ground is 0V by default.

[0061] The driving unit 110 receives the control signal sent by the control unit 130 and outputs a voltage / current excitation to the DUT. The HS voltage measurement unit 140 and the LS voltage measurement unit 150 measure the voltage of the high-side voltage line HS relative to the ground and the voltage of the low-side voltage line LS relative to the ground, respectively. The current measurement unit 120 measures the current in the loop. The control unit 130 calculates the measurement voltage / measurement current according to the received corresponding digital signals, performs feedback closed-loop control according to the measurement voltage / measurement current, and adjusts the output excitation voltage / excitation current of the driving unit 110.

[0062] In one embodiment, the current measurement unit 120 detects the voltage of the current sampling resistor R S The control unit 130 determines the corresponding sampling measured value according to the first digital signal and the second digital signal output by the current measurement unit 120, calculates the measurement current according to the sampling measured value and the set current calibration parameter. Further, the control unit 130 determines the HS sampling measured value and the LS sampling measured value according to the HS digital signal and the LS digital signal output by the HS voltage measurement unit 140 and the LS voltage measurement unit 150, respectively, and calculates the measurement voltage according to the HS sampling measured value, the LS sampling measured value, and the set voltage calibration parameter.

[0063] In addition, the power supply device can further comprise a multimeter for current measurement calibration and / or voltage measurement calibration; wherein the multimeter respectively detects the current sampling resistance R S The two-end ground voltage meter value detects the current flowing through the current sampling resistance; and / or the multimeter respectively detects the ground voltage meter value of the high-end voltage line HS and the ground voltage meter value of the low-end voltage line LS.

[0064] In one embodiment, the control unit 130 can be only a controller, which performs calibration operation on the current measurement unit 120, the HS voltage measurement unit 140 and the LS voltage measurement unit 150 according to the data collected by the current measurement unit 120, the HS voltage measurement unit 140, the LS voltage measurement unit 150 and the multimeter, and determines the current calibration parameter and the voltage calibration parameter. In another embodiment, the control unit 130 can also be a controller and a terminal, the controller is connected to the driving unit 110, the current measurement unit 120, the HS voltage measurement unit 140, the LS voltage measurement unit 150 and the terminal, and uploads the data collected by the current measurement unit 120, the HS voltage measurement unit 140 and the LS voltage measurement unit 150 to the terminal, and the terminal performs calibration operation on the current measurement unit 120, the HS voltage measurement unit 140 and the LS voltage measurement unit 150 in combination with the data collected by the multimeter, and determines the current calibration parameter and the voltage calibration parameter. When actually measuring the device under test DUT, the controller corresponds to analyzes the digital signals output by the current measurement unit 120, the HS voltage measurement unit 140 and the LS voltage measurement unit 150, and the set current calibration parameter and voltage calibration parameter, and obtains the measured current and the measured voltage, and feeds back and adjusts the excitation signal output by the driving unit 110. The controller can be an FPGA, a CPU, a CPLD, an MCU, etc., and in the present embodiment, the controller is an FPGA. The terminal can be, but is not limited to, various personal computers, notebook computers, smart phones, tablet computers and portable wearable devices, and the portable wearable device can be a smart watch, a smart bracelet, a head-mounted device, etc.

[0065] It can be understood that the specific structures of the driving unit 110, the current measurement unit 120, the HS voltage measurement unit 140 and the LS voltage measurement unit 150 are not unique. In one embodiment, as shown in FIG. 1, the driving unit 110 comprises a current source 111 and a voltage source 112, the current source 111 is connected to the high-end voltage line HS and the low-end voltage line LS, and the voltage source 112 is connected to the high-end voltage line HS and the low-end voltage line LS. Figure 2As shown, the driving unit 110 specifically comprises a digital-to-analog converter DAC and a power amplifier PA, the digital-to-analog converter DAC is connected to the control unit 130 (specifically connected to the FPGA) and the power amplifier PA, the power amplifier PA is connected to the device under test DUT through a high-end current line HF, connected to the ground end and the device under test DUT through a low-end current line LF. The digital-to-analog converter DAC receives the digital signal of the FPGA, converts it into an analog signal output to the power amplifier PA, and the power amplifier PA outputs the excitation signal to the device under test DUT through the high-end current line HF, and then flows back to the ground end through the low-end current line LF.

[0066] In one embodiment, continuing to refer to Figure 2 , the current measurement unit 120 comprises a follower operational amplifier U1, a follower operational amplifier U2, a differential operational amplifier U3, a differential operational amplifier U4, an analog-to-digital converter ADC1 and an analog-to-digital converter ADC2.

[0067] Specifically, the non-inverting input terminal of the follower operational amplifier U1 is connected to the first end of the current sampling resistor R S , the inverting input terminal of the follower operational amplifier U1 is connected to the output terminal of the follower operational amplifier U1, the output terminal of the follower operational amplifier U1 is connected to the first input terminal of the differential operational amplifier U3, the second input terminal of the differential operational amplifier U3 is connected to the ground end, the output terminal of the differential operational amplifier U3 is connected to the analog-to-digital converter ADC1, and the analog-to-digital converter ADC1 is connected to the control unit 130 (specifically connected to the FPGA). The non-inverting input terminal of the follower operational amplifier U2 is connected to the second end of the current sampling resistor R S , the inverting input terminal of the follower operational amplifier U2 is connected to the output terminal of the follower operational amplifier U2, the output terminal of the follower operational amplifier U2 is connected to the first input terminal of the differential operational amplifier U4, the second input terminal of the differential operational amplifier U4 is connected to the ground end, the output terminal of the differential operational amplifier U4 is connected to the analog-to-digital converter ADC2, and the analog-to-digital converter ADC2 is connected to the control unit 130 (specifically connected to the FPGA).

[0068] In this embodiment, one of the input terminals of the differential operational amplifiers U3 and U4 is connected to the current sampling resistor R S through the follower operational amplifiers U1 and U2 respectively, and the voltage to ground at both ends of the current sampling resistor R S is sampled respectively, and the first digital signal and the second digital signal are converted and transmitted to the FPGA.

[0069] In one embodiment, as Figure 2As shown, specifically, the HS voltage measurement unit 140 includes a follower operational amplifier U5, a differential operational amplifier U6, and an analog-to-digital converter ADC3, the non-inverting input terminal of the follower operational amplifier U5 is connected to the high-end voltage line HS, the inverting input terminal of the follower operational amplifier U5 is connected to the output terminal of the follower operational amplifier U5, the output terminal of the follower operational amplifier U5 is connected to the first input terminal of the differential operational amplifier U6, the second input terminal of the differential operational amplifier U6 is connected to the ground terminal, the output terminal of the differential operational amplifier U6 is connected to the analog-to-digital converter ADC3, and the analog-to-digital converter ADC3 is connected to the control unit 130 (specifically, to the FPGA). The output voltage of the differential operational amplifier U6 is sampled by the analog-to-digital converter ADC3 and converted into an HS digital signal to the FPGA.

[0070] Further, the LS voltage measurement unit 150 includes a follower operational amplifier U7, a differential operational amplifier U8, and an analog-to-digital converter ADC4, the non-inverting input terminal of the follower operational amplifier U7 is connected to the low-end voltage line LS, the inverting input terminal of the follower operational amplifier U7 is connected to the output terminal of the follower operational amplifier U7, the output terminal of the follower operational amplifier U7 is connected to the first input terminal of the differential operational amplifier U8, the second input terminal of the differential operational amplifier U8 is connected to the ground terminal, the output terminal of the differential operational amplifier U8 is connected to the analog-to-digital converter ADC4, and the analog-to-digital converter ADC4 is connected to the control unit 130 (specifically, to the FPGA). The output voltage of the differential operational amplifier U6 is sampled by the analog-to-digital converter ADC4 and converted into an LS digital signal to the FPGA.

[0071] In operation, the power supply device obtains the digital quantities fed back by the HS voltage measurement unit 140, the LS voltage measurement unit 150, and the current measurement unit 120, and controls the digital-to-analog converter DAC in the driving unit 110 to drive the power amplifier PA in combination with the digital PID algorithm, so as to output a voltage / current excitation to the device under test DUT through the high-end current line HF and return to the ground terminal through the low-end current line LF, thereby realizing the closed-loop feedback operation of the digital loop VI source system.

[0072] For the current measurement unit 120, the sampled value of the analog-to-digital converter ADC1 is denoted as VFB_RsH, the sampled value of the analog-to-digital converter ADC2 is denoted as VFB_VRsL, Rs is the nominal value of the current sampling resistor R S , the hardware gain of the measurement link of the analog-to-digital converter ADC1 is denoted as Gain1, and the hardware gain of the measurement link of the analog-to-digital converter ADC2 is denoted as Gain2. The current measurement has two operating modes: a low-precision mode and a high-precision mode.

[0073] In the low-precision mode, based on the logic of the hardware circuit itself, without considering the precision and non-linear error of the hardware device:

[0074] VRsH = VFB_RsH * Gain1

[0075] VRsL = VFB_RsL * Gain2

[0076] MI = (VRsH - VRsL) / Rs

[0077] The specific implementation is: real-time acquisition of the sampling machine values VFB_RsH and VFB_RsL of the analog-to-digital converters ADC1 and ADC2, and then

[0078] MI = (VFB_RsH * Gain1 - VFB_RsL * Gain2) / Rs

[0079] In the high-precision mode, the measurement link where the analog-to-digital converters ADC1 and ADC2 are located needs to be calibrated.

[0080] In one embodiment, the multimeter is used to detect the voltage table values of both ends of the current sampling resistor R S , and the current flowing through the current sampling resistor R S .

[0081] When the load is empty, the control unit 130 controls the driving unit 110 to output a plurality of different excitation voltages, respectively determines the sampling machine values in real time according to the first digital signal and the second digital signal output by the current measurement unit 120, reads the voltage table values of both ends of the current sampling resistor R S through the multimeter, performs linear fitting on the voltage table value of the first end of the current sampling resistor R S and the corresponding sampling machine value measured in each group when the load is empty, and performs linear fitting on the voltage table value of the second end of the current sampling resistor and the corresponding sampling machine value measured in each group when the load is empty, to determine the current machine value expression.

[0082] When the VI source is empty, it can be no load or a load resistor with a large resistance value (megaohm level) connected, the high-end current line HF and the high-end voltage line HS are connected together, and the low-end voltage line LS and the low-end current line LF are connected together. When the VI source is loaded, it is connected to the device under test DUT, and the VI source outputs current through the high-end current line HF, which flows back to the low-end current line LF through the device under test DUT.

[0083] As shown in Figure 3 , step Sa: the VI source outputs n groups of different excitation voltages when the load is empty, respectively reads the sampling machine values of the analog-to-digital converters ADC1 and ADC2 in real time, and the multimeter reads the voltage table values of both ends of the current sampling resistor R SThe ground voltage table measured values of the two ends are obtained as arrays VFB_RsH[n], VRsH[n], VFB_RsL[n], and VRsL[n].

[0084] Step Sb: the ground voltage table measured value VRsH[n] of the first end of the current sampling resistor R S and the corresponding sampling machine measured value VFB_RsH[n] are monodromy linearly fitted, and the ground voltage table measured value VRsL[n] of the second end of the current sampling resistor R S and the corresponding sampling machine measured value VFB_RsL[n] are monodromy linearly fitted, and the values of kRsH, bRsH, kRsL, and bRsL in VRsH=VFB_RsH*Gain1*kRsH+bRsH and VRsL=VFB_RsL*Gain2*kRsL+bRsL are calculated to obtain the current machine measured value expression:

[0085] MI machine measured value=[(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs

[0086] wherein VFB_RsH and VFB_RsL are sampling machine measured values of the analog-to-digital converter ADC1 and the analog-to-digital converter ADC2 respectively, Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, and Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located; VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the ground voltage machine measured values of the first end and the second end of the current sampling resistor R S , that is, the ground voltage of the first end of the current sampling resistor R S and the ground voltage of the second end of the current sampling resistor R S .

[0087] Further, the control unit 130 controls the driving unit 110 to output a plurality of groups of different excitation currents, respectively determines the corresponding sampling machine measured values in real time according to the first digital signal and the second digital signal output by the current measurement unit 120, reads the current table measured value flowing through the current sampling resistor R S by using the multimeter, calculates the current machine measured value of each group based on each group of sampling machine measured values and the current machine measured value expression, performs linear fitting according to the current machine measured value of each group and the measured current table measured value of each group, and determines the current calibration parameter.

[0088] It is to be noted that the above description is merely an example, and the current calibration parameter can also be determined by other methods. Figure 3, step Sc: VI source with load output m groups of different current excitation, respectively, real-time read the sampling machine value of analog-to-digital converter ADC1 and analog-to-digital converter ADC2, multimeter reads the current meter value of current sampling resistor R S , obtain the array VFB_RsH[m], VFB_RsL[m], IMRs[m].

[0089] Step Sd: VFB_RsH[m], VFB_RsL[m] are substituted into the current measurement value expression to obtain the array MI measured value[m].

[0090] Step Se: MI measured value[m] and IMRs[m] are fitted by a linear equation (Rs is not accurate, and MI measured value needs to be corrected), and the values of kMI and bMI in IMRs=MI measured value*kMI+bMI are calculated. The calculation formula of the measured current is:

[0091] MI=kMI*[(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs+bMI

[0092] Wherein, MI is the measured current, kMI, bMI, kRsH, bRsH, kRsL, bRsL are current calibration parameters, VFB_RsH, VFB_RsL are the sampling machine values of analog-to-digital converter ADC1 and analog-to-digital converter ADC2 respectively; Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, and Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located. VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the ground voltage measurement values of the first end and the second end of the current sampling resistor respectively. Set kMI, kRsH, kRsL to 1 and bMI, bRsH, bRsL to 0, which is the low precision mode.

[0093] For the HS voltage measurement unit 140 and the LS voltage measurement unit 150, the HS sampling machine value of the analog-to-digital converter ADC3 is denoted as VFB_HS, the LS sampling machine value of the analog-to-digital converter ADC4 is denoted as VFB_LS, the hardware gain of the analog-to-digital converter ADC3 measurement link is denoted as Gain3, and the hardware gain of the analog-to-digital converter ADC4 measurement link is denoted as Gain4. The voltage measurement is also divided into two operation modes: low precision mode and high precision mode.

[0094] In the low precision mode, based on the logic of the hardware circuit itself, without considering the precision and non-linear error of the hardware device:

[0095] VHS=VFB_HS*Gain3

[0096] VLS=VFB_LS*Gain4

[0097] MV=VHS-VLS

[0098] The specific implementation is that the HS sampler measured value VFB_HS of the analog-to-digital converter ADC3 and the LS sampler measured value VFB_LS of the analog-to-digital converter ADC4, then

[0099] MV=VFB_HS*Gain3-VFB_LS*Gain4

[0100] In the high-precision mode, the measurement link where the analog-to-digital converter ADC3 and the analog-to-digital converter ADC4 are located needs to be calibrated.

[0101] In one embodiment, the multimeter is also used to detect the voltmeter measured value of the high-end voltage line HS to ground and the voltmeter measured value of the low-end voltage line LS to ground, respectively.

[0102] When the load is applied, the control unit 130 controls the driving unit 110 to output a plurality of different excitation currents, and the HS sampler measured value and the LS sampler measured value are obtained in real time, respectively. The multimeter reads the HS voltmeter measured value to ground and the LS voltmeter measured value to ground, respectively. Linear fitting is performed based on each group of HS sampler measured value and HS voltmeter measured value to ground, and linear fitting is performed based on each group of LS sampler measured value and LS voltmeter measured value to ground, to determine the voltage calibration parameters.

[0103] As shown in Figure 4 Step Sf: VI source applies n groups of different current excitation, and reads the HS sampler measured value of the analog-to-digital converter ADC3 and the LS sampler measured value of the analog-to-digital converter ADC4 in real time, respectively. The multimeter reads the HS voltmeter measured value to ground and the LS voltmeter measured value to ground, to obtain the arrays VFB_HS[n], VHS[n], VFB_LS[n], and VLS[n].

[0104] Step Sg: Perform one-dimensional linear fitting on the HS sampler measured value VFB_HS[n] and the HS voltmeter measured value VHS[n] to ground, and perform one-dimensional linear fitting on the LS sampler measured value VFB_LS[n] and the LS voltmeter measured value VLS[n] to ground, to calculate the values of kHS, bHS, kLS, and bLS in VHS=VFB_HS*Gain3*kHS+bHS and VLS=VFB_LS*Gain4*kLS+bLS. The calculation formula of the measured voltage is:

[0105] MV=(VFB_HS*Gain3*kHS+bHS)-(VFB_LS*Gain4*kLS+bLS)

[0106] Wherein, MV is a measured voltage, kHS, bHS, kLS, bLS are voltage calibration parameters, VFB HS is a measured value of the HS sampling of the analog-to-digital converter ADC3, VFB LS is a measured value of the LS sampling of the analog-to-digital converter ADC4; Gain3 is the hardware gain of the link where the analog-to-digital converter ADC3 is located, and Gain4 is the hardware gain of the link where the analog-to-digital converter ADC4 is located. VFB HS*Gain3*kHS+bHS and VFB LS*Gain4*kLS+bLS are the measured values of the HS voltage to ground and the LS voltage to ground, respectively. Setting kHS and kLS to 1 and bHS and bLS to 0 is a low-precision mode.

[0107] The digital differential sampling power supply device measures the voltages to ground of the four points of the current sampling resistor Rs and the HS and LS through multiple ADCs, measures the single-ended voltage to ground first, calculates the differential voltage after converting to digital quantity in the FPGA, and then converts to the corresponding measured voltage MV and measured current MI. The hardware differential measurement of the prior art is not used, and the common-mode voltage generated by the LS does not need to be directly measured. The voltages to ground of each node are collected through multiple ADCs to avoid the common-mode influence and effectively reduce the error caused by the common-mode voltage to the voltage and current measurement.

[0108] In one embodiment, a calibration method of a current measurement unit is also provided, which is applied to a control unit. The digital differential sampling power supply device includes a driving unit, a current measurement unit, a current sampling resistor, and a control unit. The current measurement unit is connected to both ends of the current sampling resistor, detects the voltages to ground of both ends of the current sampling resistor, converts to obtain first and second digital signals, and transmits the first and second digital signals to the control unit. The driving unit is connected to a device under test through a high-end current line HF, and the device under test is connected to the internal ground end of the driving unit through a low-end current line LF. The current sampling resistor is connected in series at both ends of the high-end current line HF. The method includes:

[0109] Step S1: calculating a measured current based on a sampling measured value and a set current calibration parameter, wherein the sampling measured value is determined by the control unit based on the first and second digital signals output by the current measurement unit.

[0110] In one embodiment, an ohmmeter is used to detect the voltages to ground of both ends of the current sampling resistor and the current flowing through the current sampling resistor, respectively. Determining the set current calibration parameter includes:

[0111] Step S11: The control unit controls the driving unit to output a plurality of groups of different excitation voltages, respectively determines the sampling machine measured value in real time according to the first digital signal and the second digital signal output by the current measurement unit, reads the voltmeter measured value of the current sampling resistor through the multimeter, respectively, linearly fits the voltmeter measured value of the first end of the current sampling resistor and the corresponding sampling machine measured value measured in each group under no load, linearly fits the voltmeter measured value of the second end of the current sampling resistor and the corresponding sampling machine measured value measured in each group under no load, and determines the current machine measured value expression.

[0112] Step S12: The control unit controls the driving unit to output a plurality of groups of different excitation currents under load, respectively determines the corresponding sampling machine measured value in real time according to the first digital signal and the second digital signal output by the current measurement unit, reads the ammeter measured value of the current flowing through the current sampling resistor through the multimeter, calculates the current machine measured value of each group based on the current machine measured value and the ammeter measured value of each group under load, linearly fits the current machine measured value of each group and the ammeter measured value measured in each group, and determines the current calibration parameter.

[0113] In one embodiment, the current machine measured value expression is determined based on linear fitting of the voltmeter measured value of the first end of the current sampling resistor and the corresponding sampling machine measured value measured in each group under no load, and linear fitting of the voltmeter measured value of the second end of the current sampling resistor and the corresponding sampling machine measured value measured in each group under no load, comprising:

[0114] Step S111: Perform one-dimensional linear fitting on the voltmeter measured value of the first end of the current sampling resistor and the voltmeter measured value of the ground voltage measured in each group under no load to obtain the current calibration parameter kRsH and bRsH;

[0115] Step S112: Perform one-dimensional linear fitting on the voltmeter measured value of the second end of the current sampling resistor and the voltmeter measured value of the ground voltage measured in each group under no load to obtain the current calibration parameter kRsL and bRsL;

[0116] The current machine measured value expression is:

[0117] MI machine measured value = [(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs

[0118] Wherein, VFB_RsH and VFB_RsL are the sampling measured values of the analog-to-digital converter ADC1 and the analog-to-digital converter ADC2 respectively, Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located; VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the ground voltage measured values of the first end and the second end of the current sampling resistor respectively.

[0119] In one embodiment, the current calibration parameters are determined according to the linear fitting of the current measured value of each group and the measured ammeter value of each group, including:

[0120] Step S113: Perform monomial linear fitting on the calculated current measured value of each group and the measured ammeter value of each group to obtain the current calibration parameters kMI and bMI. The calculation formula of the measured current MI is:

[0121] MI=kMI*[(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs+bMI.

[0122] It can be understood that the calibration method of the current measurement unit is explained in detail in the above digital differential sampling power supply device, and will not be repeated here.

[0123] The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0124] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as the limitation of the patent scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A digitally differentially sampled power supply device, characterized by, The utility model relates to a kind of current measurement device, including: Drive unit, by high-end current line HF is connected to the device under test, output excitation signal to the device under test, the device under test is connected to drive unit internal ground by low-end current line LF; Current sampling resistance, series connection is set in the high-end current line HF; Current measurement unit, the two ends of the current sampling resistance are connected, the voltage to ground of the two ends of the current sampling resistance is detected respectively, and the first digital signal and the second digital signal are converted to be output to control unit; The control unit is connected to the drive unit and the current measurement unit, and the measurement current is obtained according to the received first digital signal and second digital signal, and the control signal is output to the drive unit to adjust the current of the excitation signal.

2. The power supply device according to claim 1, characterized by The control unit determines the corresponding sampling measured value according to the first digital signal and the second digital signal output by the current measurement unit, and calculates the measurement current according to the sampling measured value and the set current calibration parameter.

3. The power supply device according to claim 2, characterized by It also includes a multimeter, which is used to detect the voltage to ground of the two ends of the current sampling resistance and the current flowing through the current sampling resistance. When the control unit controls the drive unit to output a plurality of different excitation voltages, the sampling measured value is determined in real time according to the first digital signal and the second digital signal output by the current measurement unit, the voltage to ground of the two ends of the current sampling resistance is read by the multimeter, the linear fitting is carried out based on the voltage to ground of the first end of the current sampling resistance and the corresponding sampling measured value measured in each group when the load is empty, and the linear fitting is carried out based on the voltage to ground of the second end of the current sampling resistance and the corresponding sampling measured value measured in each group when the load is empty, to determine the current measured value expression. When the control unit controls the drive unit to output a plurality of different excitation currents, the corresponding sampling measured value is determined in real time according to the first digital signal and the second digital signal output by the current measurement unit, the current table measured value flowing through the current sampling resistance is read by the multimeter, the current measured value of each group is calculated based on the sampling measured value of each group and the current measured value expression when the load is loaded, and the linear fitting is carried out according to the current measured value of each group and the current table measured value measured in each group, to determine the current calibration parameter.

4. The power supply device according to claim 1, characterized by The current measurement unit includes a follower operational amplifier U1, a follower operational amplifier U2, a differential operational amplifier U3, a differential operational amplifier U4, an analog-to-digital converter ADC1 and an analog-to-digital converter ADC2. The non-inverting input terminal of the follower operational amplifier U1 is connected to the first end of the current sampling resistance, the inverting input terminal of the follower operational amplifier U1 is connected to the output terminal of the follower operational amplifier U1, the output terminal of the follower operational amplifier U1 is connected to the first input terminal of the differential operational amplifier U3, the second input terminal of the differential operational amplifier U3 is connected to the ground, the output terminal of the differential operational amplifier U3 is connected to the analog-to-digital converter ADC1, and the analog-to-digital converter ADC1 is connected to the control unit. The non-inverting input terminal of the follower operational amplifier U2 is connected to the second end of the current sampling resistor, the inverting input terminal of the follower operational amplifier U2 is connected to the output terminal of the follower operational amplifier U2, the output terminal of the follower operational amplifier U2 is connected to the first input terminal of the differential operational amplifier U4, the second input terminal of the differential operational amplifier U4 is connected to the ground terminal, and the output terminal of the differential operational amplifier U4 is connected to the analog-to-digital converter ADC2, and the analog-to-digital converter ADC2 is connected to the control unit.

5. The power supply device according to claim 4, characterized by The calculation formula of the measurement current is: MI=kMI*[(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs+bMI wherein, MI is the measurement current, kMI, bMI, kRsH, bRsH, kRsL, and bRsL are current calibration parameters, VFB_RsH and VFB_RsL are the sampling measured values of the analog-to-digital converter ADC1 and the analog-to-digital converter ADC2 respectively, Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, and Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located, and VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the ground voltage measured values of the first end and the second end of the current sampling resistor respectively.

6. The power supply device according to any one of claims 1 to 5, characterized by Further comprising: a HS voltage measurement unit connected to the device to be measured through a high-side voltage line HS, detecting the ground voltage of the high-side voltage line HS, and converting to obtain a HS digital signal and transmitting to the control unit; a LS voltage measurement unit connected to the device to be measured through a low-side voltage line LS, detecting the ground voltage of the low-side voltage line LS, and converting to obtain a LS digital signal and transmitting to the control unit; the control unit is also connected to the HS voltage measurement unit and the LS voltage measurement unit, and the control unit analyzes the measurement voltage according to the received HS digital signal and LS digital signal, and performs feedback adjustment according to the measurement voltage, and outputs a control signal to the driving unit to adjust the voltage of the excitation signal.

7. The power supply device according to claim 6, wherein The control unit determines the HS sampling measured value and the LS sampling measured value according to the HS digital signal and the LS digital signal output by the HS voltage measurement unit and the LS voltage measurement unit respectively, and calculates the measurement voltage according to the HS sampling measured value, the LS sampling measured value and the set voltage calibration parameter.

8. The power supply device according to claim 7, characterized by The multimeter is also used to detect the ground voltage table measured value of the high-side voltage line HS and the ground voltage table measured value of the low-side voltage line LS respectively; When loaded, the control unit controls the driving unit to output a plurality of different excitation currents, and respectively obtains the HS sampling measured value and the LS sampling measured value in real time, reads the HS ground voltage table measured value and the LS ground voltage table measured value through the multimeter, performs linear fitting based on each group of HS sampling measured value and HS ground voltage table measured value, and performs linear fitting based on each group of LS sampling measured value and LS ground voltage table measured value, and determines the voltage calibration parameter.

9. The power supply device of claim 6, wherein, the HS voltage measurement unit comprises a follower operational amplifier U5, a differential operational amplifier U6 and an analog-to-digital converter ADC3, the non-inverting input terminal of the follower operational amplifier U5 is connected to the high-end voltage line HS, the inverting input terminal of the follower operational amplifier U5 is connected to the output terminal of the follower operational amplifier U5, the output terminal of the follower operational amplifier U5 is connected to the first input terminal of the differential operational amplifier U6, the second input terminal of the differential operational amplifier U6 is connected to the ground terminal, the output terminal of the differential operational amplifier U6 is connected to the analog-to-digital converter ADC3, and the analog-to-digital converter ADC3 is connected to the control unit; the LS voltage measurement unit comprises a follower operational amplifier U7, a differential operational amplifier U8 and an analog-to-digital converter ADC4, the non-inverting input terminal of the follower operational amplifier U7 is connected to the low-end voltage line LS, the inverting input terminal of the follower operational amplifier U7 is connected to the output terminal of the follower operational amplifier U7, the output terminal of the follower operational amplifier U7 is connected to the first input terminal of the differential operational amplifier U8, the second input terminal of the differential operational amplifier U8 is connected to the ground terminal, the output terminal of the differential operational amplifier U8 is connected to the analog-to-digital converter ADC4, and the analog-to-digital converter ADC4 is connected to the control unit.

10. The power supply device according to claim 9, wherein The calculation formula of the measured voltage is: MV = (VFB_HS*Gain3*kHS+bHS)-(VFB_LS*Gain4*kLS+bLS) wherein MV is the measured voltage, kHS, bHS, kLS and bLS are voltage calibration parameters, VFB_HS is the HS sampling measured value of the analog-to-digital converter ADC3, VFB_LS is the LS sampling measured value of the analog-to-digital converter ADC4, Gain3 is the hardware gain of the link where the analog-to-digital converter ADC3 is located, Gain4 is the hardware gain of the link where the analog-to-digital converter ADC4 is located, VFB_HS*Gain3*kHS+bHS is the HS voltage measured value, and VFB_LS*Gain4*kLS+bLS is the LS voltage measured value.

11. A method of calibrating a current measuring unit, characterized by, The digital differential sampling power supply device applied to the control unit comprises a driving unit, a current measurement unit, a current sampling resistor and a control unit, the current measurement unit is connected to both ends of the current sampling resistor, detects the ground voltage at both ends of the current sampling resistor, converts the first digital signal and the second digital signal to be transmitted to the control unit; the driving unit is connected to the device to be measured through the high-end current line HF, and the device to be measured is connected to the internal ground terminal of the driving unit through the low-end current line LF; the current sampling resistor is connected in series at both ends of the high-end current line HF; The method comprises: based on the sampling measured value and the set current calibration parameters, the measured current is calculated, wherein the sampling measured value is determined by the control unit according to the first digital signal and the second digital signal output by the current measurement unit.

12. The method of claim 11, wherein, The multimeter is used to detect the voltage-to-ground meter value between the two ends of the current sampling resistor and the current flowing through the current sampling resistor, respectively; The current calibration parameter determined includes: When the load is empty, the control unit controls the driving unit to output a plurality of different excitation voltages, and determines the sampling machine measurement value in real time according to the first digital signal and the second digital signal output by the current measurement unit, respectively, reads the voltage-to-ground meter value between the two ends of the current sampling resistor through the multimeter, performs linear fitting on the voltage-to-ground meter value of the first end of the current sampling resistor and the corresponding sampling machine measurement value measured in each group when the load is empty, and performs linear fitting on the voltage-to-ground meter value of the second end of the current sampling resistor and the corresponding sampling machine measurement value measured in each group when the load is empty, to determine the current machine measurement value expression; When the load is loaded, the control unit controls the driving unit to output a plurality of different excitation currents, and determines the corresponding sampling machine measurement value in real time according to the first digital signal and the second digital signal output by the current measurement unit, reads the current meter value flowing through the current sampling resistor through the multimeter, calculates the current machine measurement value of each group based on the sampling machine measurement value of each group and the current machine measurement value expression when the load is loaded, and performs linear fitting on the current machine measurement value of each group and the current meter value measured in each group to determine the current calibration parameter.

13. The method of claim 12, wherein, The current machine measurement value expression is determined by performing linear fitting on the voltage-to-ground meter value of the first end of the current sampling resistor and the corresponding sampling machine measurement value measured in each group when the load is empty, and performing linear fitting on the voltage-to-ground meter value of the second end of the current sampling resistor and the corresponding sampling machine measurement value measured in each group when the load is empty, including: The current calibration parameters kRsH and bRsH are obtained by performing one-dimensional linear fitting on the voltage-to-ground machine measurement value and the voltage-to-ground meter value of the first end of the current sampling resistor measured in each group when the load is empty; The current calibration parameters kRsL and bRsL are obtained by performing one-dimensional linear fitting on the voltage-to-ground machine measurement value and the voltage-to-ground meter value of the second end of the current sampling resistor measured in each group when the load is empty; The current machine measurement value expression is: MI machine measurement value = [(VFB_RsH*Gain1*kRsH+bRsH)-(VFB_RsL*Gain2*kRsL+bRsL)] / Rs Wherein, VFB_RsH and VFB_RsL are the sampling machine measurement values of the analog-to-digital converter ADC1 and the analog-to-digital converter ADC2, Rs is the nominal value of the current sampling resistor, Gain1 is the hardware gain of the link where the analog-to-digital converter ADC1 is located, Gain2 is the hardware gain of the link where the analog-to-digital converter ADC2 is located; VFB_RsH*Gain1*kRsH+bRsH and VFB_RsL*Gain2*kRsL+bRsL are the voltage-to-ground machine measurement values of the first end and the second end of the current sampling resistor, respectively.

14. The method of claim 13, wherein, The current calibration parameter is determined by performing linear fitting on the current machine measurement value of each group and the current meter value measured in each group, including: The current calibration parameters kMI and bMI are obtained by performing one-dimensional linear fitting on the current machine measurement value calculated in each group and the current meter value measured in each group; The calculation formula of the measured current MI is: MI = kMI * [(VFB_RsH * Gainl * kRsH + bRsH) - (VFB_RsL * Gain2 * kRsL + bRsL)] / Rs + bMI.

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