SMU and self-calibration method of SMU

Abstract

The invention provides an SMU and a self-calibration method of the SMU, and relates to the technical field of the SMU. The SMU comprises a calibration module used for outputting a reference signal to a measurement module during calibration; the measurement module is used for receiving a reference signal and transmitting the reference signal to the ADC module; the ADC module is used for generating a first measurement result according to the reference signal so as to calibrate the measurement function of the SMU, and the measurement function calibration is realized based on the first measurement result and the reference signal; and the DAC module is used for sending a test signal to the measurement module to calibrate the output function of the SMU after the calibration of the measurement function is completed, and the calibration of the output function is realized through a second measurement result corresponding to the test signal and the test signal. According to the embodiment of the invention, the accuracy of voltage measurement, current measurement and signal output can be improved, so that the SMU can realize long-time accurate measurement and accurate signal output in various environments, and the reliability of the SMU is improved.

Description

Technical Field

[0001] The present application relates to the field of SMU technology, and in particular, to an SMU and a self-calibration method of the SMU. Background Art

[0002] As a high-precision source measurement device, SMU (Source Measure Unit) must not only ensure high-precision output capabilities, but also maintain high-precision measurement capabilities. However, after the SMU leaves the factory, the device needs to face a variety of usage environments. The precision components in the circuits of the measurement modules used for measurement in the device will be affected by the usage environment, resulting in reduced accuracy of the measurement results; and as time goes by, these precision components will also have the risk of aging and long-term drift, which will cause the measurement and output functions of the SMU to become unreliable. A method is needed to maintain the measurement accuracy of the measurement module and output accurate signals. Summary of the invention

[0003] The embodiments of the present application provide an SMU and a self-calibration method for the SMU, which can solve the problems of reduced accuracy of the existing SMU after leaving the factory, inaccurate measurement results and reduced accuracy of the output signal.

[0004] In order to achieve this purpose, the embodiments of the present application provide the following solutions.

[0005] According to one aspect of an embodiment of the present application, there is provided an SMU, comprising an ADC module, a DAC module, a measurement module, and a calibration module provided with a voltage reference circuit and a current reference circuit, wherein the measurement module is connected to the calibration module, the ADC module, and the DAC module, respectively, and the calibration module is used to output a reference signal to the measurement module during calibration, wherein the reference signal comprises a voltage signal or a current signal;

[0006] The measuring module is used to receive the reference signal and transmit the reference signal to the ADC module;

[0007] The ADC module is used to generate a first measurement result according to the reference signal to calibrate the measurement function of the SMU, and the measurement function calibration is implemented based on the first measurement result and the reference signal;

[0008] The DAC module is used to send a test signal to the measurement module to calibrate the output function of the SMU after the measurement function calibration is completed. The calibration of the output function is achieved through a second measurement result and the test signal. The second measurement result is generated by the ADC module based on the test signal transmitted by the measurement module.

[0009] In one possible implementation, the calibration module includes a power supply circuit having a power supply and a reference chip, the output end of the power supply is connected to the input end of the reference chip, the voltage output end of the reference chip is connected to the input ends of the voltage reference circuit and the current reference circuit, and the reference chips connected to the voltage reference circuit and the current reference circuit are the same or different.

[0010] In one possible implementation, the voltage reference circuit and the current reference circuit are connected to the same reference chip, the output end of the voltage reference circuit is connected to the voltage detection end of the measurement module, the first output end of the current reference circuit is connected to the current detection end of the measurement module, and the second output end of the current reference circuit is connected to the ground end of the reference chip.

[0011] In one possible implementation, the power supply circuit includes an eighth control switch and a tenth control switch, the first end of the eighth control switch is connected to the first end of the tenth control switch and the ground end of the reference chip, the second end of the eighth control switch is grounded, and the second end of the tenth control switch is connected to the second output end of the current reference circuit.

[0012] In a possible implementation, the voltage reference circuit includes a first buffer circuit, a first voltage circuit, and a second voltage circuit, the input end of the buffer circuit is connected to the output end of the power supply circuit, the output end of the buffer circuit is connected to the input end of the first voltage circuit, and the voltage signals output by the first voltage circuit and the second voltage circuit are different;

[0013] The first voltage circuit comprises a sixth control switch, a first end of the sixth control switch is connected to an input end of the second voltage circuit, and a second end of the sixth control switch is connected to an output end of the second voltage circuit and a voltage measuring end of the measuring module;

[0014] The second voltage circuit includes a seventh control switch for controlling the on and off of the second voltage circuit, and a second end of the seventh control switch is connected to a voltage measuring end of the measuring module.

[0015] In a possible implementation, the voltage signals output by the first voltage circuit and the second voltage circuit are different, and the first voltage circuit also includes a fifteenth resistor, an eighth resistor, and a second operational amplifier, the first end of the fifteenth resistor is connected to the output end of the buffer circuit, the second end of the eighth resistor is grounded, the first end of the eighth resistor is connected to the second end of the fifteenth resistor and the non-inverting input end of the second operational amplifier, and the inverting input end of the second operational amplifier is connected to the input end of the second voltage circuit and the first end of the sixth control switch.

[0016] In one possible implementation, the current reference circuit includes a second buffer circuit and multiple current circuits, the input end of the second buffer circuit is connected to the power supply circuit, the current circuits are arranged in parallel and the input end of the current circuit is connected to the output end of the second buffer circuit, and the output end of the current circuit is connected to the ground end of the reference chip and the current measurement end of the measurement module.

[0017] In one possible implementation, the current reference circuit includes a seventh operational amplifier and a ninth control switch, the output end of the current circuit is connected to the non-inverting input end of the seventh operational amplifier and the first end of the ninth control switch, the inverting input end of the seventh operational amplifier is connected to the ground end of the reference chip and the output end of the seventh operational amplifier, and the second end of the ninth control switch is connected to the current measurement end of the measurement module.

[0018] In a possible implementation, the current circuit includes a circuit control switch and a current adjustment resistor. The first end of the circuit control switch is connected to the output end of the second buffer circuit, the second end of the circuit control switch is connected to the first end of the current adjustment resistor, and the second end of the current adjustment resistor is connected to the ground end of the reference chip and the current measurement end of the measurement module. Different current circuits have different resistance values.

[0019] According to one aspect of an embodiment of the present application, a self-calibration method of an SMU is provided, which is used for the SMU as described above, and the self-calibration method includes:

[0020] Determine the working mode of the measurement module, and control the calibration module to output a reference signal according to the working mode, wherein the reference signal includes a voltage signal or a current signal;

[0021] Using a measurement module to transmit the reference signal to the ADC module, and obtaining a first measurement result of the ADC module in response to the reference signal;

[0022] calibrating a measurement function of the SMU according to the first measurement result and the reference signal;

[0023] Determine that the measurement function calibration is completed, use the measurement module to transmit the test signal sent by the DAC module to the ADC module, and obtain a second measurement result of the ADC module in response to the test signal;

[0024] An output function of the SMU is calibrated according to the second measurement result and the test signal.

[0025] The beneficial effects of the technical solution provided by the embodiment of the present application are:

[0026] The SMU provided in the present application includes an ADC module, a DAC module, a measurement module, and a calibration module provided with a voltage reference circuit and a current reference circuit. The measurement module is connected to the calibration module, the ADC module, and the DAC module respectively. The calibration module is used to output a reference signal to the measurement module during calibration, and the reference signal includes a voltage signal or a current signal; the measurement module is used to receive the reference signal and transmit the reference signal to the ADC module; the ADC module is used to generate a first measurement result according to the reference signal to calibrate the measurement function of the SMU, and the measurement function calibration is based on the first measurement result and the reference signal; the DAC module is used to send a test signal to the measurement module after the measurement function calibration is completed to calibrate the output function of the SMU, and the calibration of the output function is achieved by the second measurement result and the test signal, and the second measurement result is generated by the ADC module based on the test signal transmitted by the measurement module. The embodiment of the present application can calibrate the measurement function and output function of the SMU through the voltage signal or current signal output by the calibration module in the SMU, improve the accuracy of voltage measurement, current measurement and output signal, so that the device can achieve long-term accurate measurement and accurate signal output in various environments, and improve the reliability of the SMU. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in describing the embodiments of the present application.

[0028] Figure 1 A structural diagram of the SMU provided in the embodiment of the present application;

[0029] Figure 2 A circuit diagram of a measurement module provided in an embodiment of the present application;

[0030] Figure 3 A circuit diagram of a voltage reference circuit provided in an embodiment of the present application;

[0031] Figure 4 A circuit diagram of a current reference circuit provided in an embodiment of the present application;

[0032] Figure 5 A circuit diagram of a calibration module provided in an embodiment of the present application;

[0033] Figure 6 A flow chart of a self-calibration method for an SMU provided in an embodiment of the present application. Description of the drawings:

[0035] SENSE, voltage detection terminal; OUTPUT, current detection terminal; LOW, ground port; U8, first reference chip; U5, second reference chip; U13, third reference chip;

[0036] R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; W1, first control switch; W2, second control switch; W3, third control switch; W4, fourth control switch; W5, fifth control switch; W11, eleventh control switch; W12, twelfth control switch; W13, thirteenth control switch; W14, fourteenth control switch; W15, fifteenth control switch; W16, sixteenth control switch; W8, eighth control switch; W10, tenth control switch; W6, sixth control switch; U1, first operational amplifier; R15, fifteenth resistor; R8, eighth resistor; U2, second operational amplifier; R9, ninth resistor; R11, eleventh resistor; U3, third Operational amplifier; W7, seventh control switch; U6, sixth operational amplifier; U7, seventh operational amplifier; W9, ninth control switch; R6, sixth resistor; U9, ninth operational amplifier; U10, tenth operational amplifier; U11, eleventh operational amplifier; U12, twelfth operational amplifier; U13, thirteenth operational amplifier; R7, seventh resistor; R20, twentieth resistor; R21, twenty-first resistor; R23, twenty-third resistor; R24, twenty-fourth resistor; R25, twenty-fifth resistor; R26, twenty-sixth resistor; R27, twenty-seventh resistor; R28, twenty-eighth resistor; R29, twenty-ninth resistor; R30, thirtieth resistor; R31, thirty-first resistor; R32, thirty-second resistor. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described below in conjunction with the drawings in the present application. It should be understood that the implementation methods described below in conjunction with the drawings are exemplary descriptions for explaining the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions of the embodiments of the present application.

[0038] It will be understood by those skilled in the art that, unless specifically stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the terms "including" and "comprising" used in the embodiments of the present application refer to that the corresponding features can be implemented as the presented features, information, data, steps, operations, elements and / or components, but do not exclude the implementation of other features, information, data, steps, operations, elements, components and / or combinations thereof supported by the present technical field. It should be understood that when we say that an element is "connected" or "coupled" to another element, the one element may be directly connected or coupled to the other element, or it may refer to that the one element and the other element establish a connection relationship through an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein indicates at least one of the items defined by the term, for example, "A and / or B" indicates that it is implemented as "A", or is implemented as "A", or is implemented as "A and B".

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0040] The following describes several exemplary embodiments to illustrate the technical solutions of the embodiments of the present invention and the technical effects produced by the technical solutions of the present invention. It should be noted that the following embodiments can refer to, draw on or combine with each other, and the same terms, similar features and similar implementation steps in different embodiments will not be described repeatedly.

[0041] The SMU and the SMU self-calibration method provided in the present application are intended to solve at least one technical problem existing in the prior art.

[0042] In an embodiment of the present application, a SMU is provided, such as Figure 1-Figure 5As shown, the SMU includes an ADC module, a DAC module, a measurement module, and a calibration module provided with a voltage reference circuit and a current reference circuit. The measurement module is connected to the calibration module, the ADC module, and the DAC module respectively. The calibration module is used to output a reference signal to the measurement module during calibration, and the reference signal includes a voltage signal or a current signal; the measurement module is used to receive the reference signal and transmit the reference signal to the ADC module; the ADC module is used to generate a first measurement result according to the reference signal to calibrate the measurement function of the SMU, and the measurement function calibration is implemented based on the first measurement result and the reference signal; the DAC module is used to output a signal through the measurement module and send a test signal to the measurement module after the measurement function calibration is completed to calibrate the output function of the SMU, and the calibration of the output function is implemented through the second measurement result and the test signal, and the second measurement result is generated by the ADC module based on the test signal transmitted by the measurement module. Among them, the calibration of the measurement function includes the calibration of the voltage measurement function and the current measurement function, and the calibration of the output function includes the calibration of the voltage output function and the current output function.

[0043] Optionally, the measurement module can also be connected to an external device, and the measurement function and output function of the SMU can be calibrated through the external device. The external device can be a high-precision voltmeter, ammeter, or other device capable of measuring high-precision signals. Specifically, the external device can be a multimeter, and its model can be 3458A.

[0044] Optionally, the measurement module may include a voltage detection terminal SENSE, a current detection terminal OUTPUT and a ground port LOW, and voltage detection is performed through the voltage detection terminal SENSE, and current detection is performed using the current detection terminal OUTPUT.

[0045] In one embodiment, the measurement module connects a resistor in series in the output path, detects the current flowing in the circuit by detecting the voltage on the resistor, and a smaller current gear in the measurement module uses a larger resistor to achieve a smaller current resolution; the measurement module detects the voltage difference between the output voltage detection terminal SENSE and the ground port LOW, sets the range through different voltage division ratios, and finally returns a value of a suitable size to the device to measure the voltage, and a smaller voltage gear uses a smaller voltage division ratio to achieve a better voltage resolution.

[0046] Specifically, the circuit of the measurement module can be as follows Figure 2As shown, the SENSE port is connected to the eleventh operational amplifier U11, the output end of the eleventh operational amplifier U11 is connected to the first end of the twenty-fifth resistor R25 and the first end of the twenty-third resistor R23, the second end of the twenty-third resistor R23 is connected to the first end of the sixteenth control switch W16, the non-inverting input end of the tenth operational amplifier U10, and the first end of the twentieth resistor R20, the second end of the sixteenth control switch W16 is connected to the first end of the thirty-second resistor R32, the second end of the thirty-second resistor R32 is connected to the second end of the twentieth resistor R20, the output end of the twelfth operational amplifier U12, and the inverting input end of the twelfth operational amplifier U12. The non-inverting input end of the twelfth operational amplifier U12 is connected to the LOW port. The inverting input terminal of the tenth operational amplifier U10 is connected to the output terminal of the tenth operational amplifier U10 and the first terminal of the twenty-first resistor R21. The second terminal of the twenty-first resistor R21 is connected to the first terminal of the twenty-fourth resistor R24 ​​and the in-phase input terminal of the ninth operational amplifier U9. The second terminal of the twenty-fourth resistor R24 ​​is connected to the first terminal of the twenty-seventh resistor R27, the first terminal of the twenty-eighth resistor R28, the first terminal of the twenty-ninth resistor R29, the first terminal of the thirtieth resistor R30, and the first terminal of the thirty-first resistor R31. The inverting input terminal of the ninth operational amplifier U9 is connected to the second terminal of the twenty-fifth resistor R25 and the second terminal of the twenty-sixth resistor R26. The first terminal of the twenty-sixth resistor R26 is connected to the output terminal of the ninth operational amplifier U9 and the V-Meas port. The current through the SENSE port is 0. When actually used, it measures the voltage on the load together with the LOW port. The SENSE port and the LOW port can be understood as the positive and negative of the voltmeter; when the SENSE port is independent of the OUTPUT port, the voltage of the load can be measured more accurately. The OUTPUT port is the port for outputting current signals, and the LOW port is a ground port LOW relative to the OUTPUT. The actual output current will flow into the LOW port after being output from the OUTPUT port, or will be reversely input from the LOW port to the OUTPUT port.

[0047] The voltage range of the measurement module includes 500mV, 5V and 20V. The voltage range is divided by the resistance ratio of the twenty-third resistor R23, the thirty-second resistor R32 and the twentieth resistor R20, and the two measured voltage values ​​are converted into one voltage value, that is, the differential voltage is converted into a single-ended voltage.

[0048] The current gears are 10mA, 100uA, 1uA, 10nA and 100pA. The OUTPUT port for current detection is connected to the in-phase input terminal of the thirteenth operational amplifier U13, the first end of the eleventh control switch W11, the first end of the twelfth control switch W12, the first end of the thirteenth control switch W13, the first end of the fourteenth control switch W14, and the first end of the fifteenth control switch W15. The inverting input terminal of the thirteenth operational amplifier U13 is connected to the output terminal of the thirteenth operational amplifier U13 and the I-Meas port. The second end of the eleventh control switch W11 is connected to the second end of the twenty-seventh resistor R27. The second end of the twenty-eighth resistor R28 is connected to the second end of the twelfth control switch W12, the second end of the twenty-ninth resistor R29 is connected to the second end of the thirteenth control switch W13, the second end of the thirtieth resistor R30 is connected to the second end of the fourteenth control switch W14, and the second end of the thirty-first resistor R31 is connected to the second end of the fifteenth control switch W15. The gear position is adjusted by opening and closing the eleventh control switch W11, the twelfth control switch W12, the thirteenth control switch W13, the fourteenth control switch W14, and the fifteenth control switch W15. The current signal detected by the measurement module is transmitted to the ADC module and the DAC module through the I-Meas port, and the detection result is read through the ADC module. The voltage signal detected by the measurement module is transmitted to the ADC module and the DAC module through the V-Meas port, and the detection result of the voltage signal is obtained through the ADC module. The DAC module can also output an accurate voltage signal or an accurate current signal through the measurement module. The SMU is displayed according to the detection result read by the ADC module or the signal output by the DAC module. The potential of F_COM in the circuit is in a floating state, and the potential is 0. Therefore, the voltage measured by the eleventh operational amplifier U11 is the voltage on the resistor, which is proportional to the current.

[0049] Optionally, when using the calibration module for self-calibration, the corresponding calibration module output corresponding reference signal can be selected according to the working mode set by the SMU, and the measurement result corresponding to the reference signal output by the ADC module is obtained. The ADC module is calibrated according to the deviation between the measurement result and the reference signal so that the measurement result output by the calibrated ADC module is consistent with the signal value of the reference signal.

[0050] Optionally, after the measurement function is calibrated, a test signal of a specific value (such as a specific voltage value or a specific current value) can be output to the measurement module through the DAC module. The measurement module transmits the test signal to the ADC module, and the ADC module outputs the measurement value of the test signal. The output function of the SMU is calibrated according to the deviation between the measurement value and the specific value so that when the calibrated DAC module outputs a signal of a specified value, the measurement value of the signal by the ADC module is consistent with the specified value.

[0051] In one embodiment, the SMU is set to current mode, which sends out a current of 0A. At this time, the SMU can measure any voltage (input voltage). At this time, the voltage reference circuit of the calibration module can output a voltage of 7mV (reference value), and the ADC module of the SMU reads a value of 6mV (read value). The voltage reference circuit then outputs a voltage of 14mV (reference value) to the measurement module, and the ADC module of the SMU can read a value of 12mV (read value); the two sets of data of the reference value and the read value can be used to complete the calibration of the voltage measurement function. After calibration, the read value of the ADC module is accurate. Then, the SMU is set to voltage mode. At this time, the SMU sends out a signal of setting the voltage and also measures its actual output voltage (output voltage). At this time, the DAC module can output a voltage of 7mv (set value), and the ADC module of the SMU reads a value of 8mv (read value). The DAC module then outputs a voltage of 14mv (reference value) to the measurement module, and the ADC module can read a value of 16mv (read value); the two sets of data of the set value and the read value can be used to complete the calibration of the voltage output function.

[0052] In another embodiment, the SMU is set to voltage mode, which sends out a voltage of 0V. At this time, the SMU can measure any current (input current). At this time, the current reference circuit of the calibration module can output a current of 7mA (reference value), and the ADC module of the SMU reads a value of 6mA (read value). The current reference circuit then outputs a current of 14mA (reference value) to the measurement module, and the ADC module of the SMU can read a value of 12mA (read value); the calibration of the current measurement function can be completed using these two sets of data of the reference value and the read value, and the read value is accurate after calibration. Then, the SMU is set to current mode, and at this time the SMU sends out a set current and also measures its actual output current (output current). At this time, the DAC module can output a current of 7mA (set value), and the ADC module of the SMU reads a value of 8mA (read value). The DAC module then outputs a current of 14mA (reference value) to the measurement module, and the ADC module can read a value of 16mA (read value); the calibration of the current output function can be completed using these two sets of data of the set value and the read value.

[0053] Optionally, the calibration module includes a power supply circuit provided with a power supply and a reference chip, the output end of the power supply is connected to the input end of the reference chip, the voltage output end of the reference chip is connected to the input end of the voltage reference circuit and the current reference circuit, and the reference chips connected to the voltage reference circuit and the current reference circuit are the same or different. Among them, the reference chip is a high-precision reference chip, which outputs a voltage signal with good stability, and the voltage reference circuit and the current reference circuit output accurate reference signals according to the voltage signal. The size of the voltage signal output by the reference chip can be adjusted according to the structure of the voltage reference circuit and the current reference circuit and actual needs.

[0054] In one embodiment, one end of the power supply is grounded, and the other end is connected to the input end of the reference chip. The power supply outputs a 15V voltage signal to the reference chip. After the reference chip processes the voltage signal, it outputs a 7V DC signal to the voltage reference circuit and the current reference circuit. The voltage signals received by the current reference circuit and the voltage reference circuit and output by the reference chip may be the same or different in size.

[0055] In one embodiment, when the voltage reference circuit and the current reference circuit are connected to different reference chips, the reference chips include a first reference chip U8 and a second reference chip U5, the first reference chip U8 is connected to the voltage reference circuit, and the second reference chip U5 is connected to the current reference circuit. When the connected reference chips are the same, the reference chips include a third reference chip U13, and the voltage reference circuit and the current reference circuit are both connected to the third reference chip U13.

[0056] Optionally, when the voltage reference circuit and the current reference circuit are connected to the same reference chip, the output end of the voltage reference circuit is connected to the voltage detection end SENSE of the measurement module, the first output end of the current reference circuit is connected to the current detection end OUTPUT of the measurement module, and the second output end of the current reference circuit is connected to the ground end of the reference chip.

[0057] Optionally, to avoid mutual interference between the voltage reference circuit and the current reference circuit, the power supply circuit includes an eighth control switch W8 and a tenth control switch W10, wherein the first end of the eighth control switch W8 is connected to the first end of the tenth control switch W10 and the ground end of the reference chip, the second end of the eighth control switch W8 is grounded, and the second end of the tenth control switch W10 is connected to the second output end of the current reference circuit. When the voltage reference circuit outputs the reference signal, the eighth control switch W8 is closed and the tenth control switch W10 is turned off, and when the current reference circuit outputs the reference signal, the tenth control switch W10 is closed and the eighth control switch W8 is turned off.

[0058] Optionally, the voltage reference circuit includes a first buffer circuit, a first voltage circuit and a second voltage circuit, the input end of the buffer circuit is connected to the output end of the power supply circuit, the output end of the buffer circuit is connected to the input end of the first voltage circuit, and the voltage signals output by the first voltage circuit and the second voltage circuit are different; the first voltage circuit includes a sixth control switch W6, the first end of the sixth control switch W6 is connected to the input end of the second voltage circuit, and the second end is connected to the output end of the second voltage circuit and the voltage measurement end of the measurement module. The second voltage circuit includes a seventh control switch W7 for controlling the on and off of the second voltage circuit, and the second end of the seventh control switch W7 is connected to the voltage measurement end SENSE of the measurement module.

[0059] In one embodiment, the voltage detection gears included in the measurement module include 20V gear, 5V gear and 500mV gear, the first voltage circuit outputs a 4.7V voltage signal, and the second voltage circuit outputs a 0.47V voltage signal. During calibration, if the gear of the measurement module is 20V gear or 5V gear, a 4.7V voltage signal is output through the first voltage circuit, and calibration is performed based on the voltage signal. If the gear of the measurement module is 500mV gear, a 0.47V voltage signal is output through the second voltage circuit for calibration.

[0060] Optionally, the voltage signal output by the reference chip is buffered by the first buffer circuit and then transmitted to the first voltage circuit through the first buffer circuit. The first buffer circuit includes a first operational amplifier U1, the non-inverting input terminal of the first operational amplifier U1 is connected to the output terminal of the reference chip, and the inverting input terminal is connected to the output terminal of the first operational amplifier U1 and the input terminal of the first voltage circuit.

[0061] Optionally, to ensure the accuracy of the reference signal output by the voltage reference circuit, the PCB board on which the circuit reference circuit is laid out adopts single-point grounding processing, and each reference ground in the circuit is grounded separately through a wire, thereby avoiding common impedance coupling and improving signal accuracy.

[0062] Optionally, the voltage signals output by the first voltage circuit and the second voltage circuit are different. The first voltage circuit also includes a fifteenth resistor R15, an eighth resistor R8, and a second operational amplifier U2. The first end of the fifteenth resistor R15 is connected to the output end of the buffer circuit, the second end of the eighth resistor R8 is grounded, the first end of the eighth resistor R8 is connected to the second end of the fifteenth resistor R15 and the in-phase input end of the second operational amplifier U2, and the inverting input end of the second operational amplifier U2 is connected to the input end of the second voltage circuit and the first end of the sixth control switch W6.

[0063] Optionally, the fifteenth resistor R15 and the eighth resistor R8 are a set of proportional resistors with a ratio of 1:2, and the voltage signal output by the first voltage circuit is implemented to be two-thirds of the input voltage signal through the proportional resistors.

[0064] Optionally, the circuit structure of the second voltage circuit is the same as that of the first voltage circuit, wherein the second voltage circuit further includes a ninth resistor R9, an eleventh resistor R11, and a third operational amplifier U3, wherein the first end of the ninth resistor R9 is connected to the output end of the second operational amplifier U2, the second end of the ninth resistor R9 is connected to the second end of the eleventh resistor R11 and the in-phase input end of the third operational amplifier U3, the second end of the eleventh resistor R11 is grounded, the inverting input end of the third operational amplifier U3 is connected to the output end of the third operational amplifier U3 and the first end of the seventh control switch W7, and the second end of the seventh control switch W7 is connected to the second end of the sixth control switch W6. The magnitude of the voltage signal output by the voltage reference circuit is adjusted by controlling the opening and closing of the sixth control switch W6 and the seventh control switch W7.

[0065] In one embodiment, the ninth resistor R9 and the eleventh resistor R11 are a set of proportional resistors, and the ratio of the two is 9:1. Through the proportional resistor, the output voltage of the second voltage circuit is one tenth of the input voltage. The high-precision reference voltage output by the reference chip, the buffering of the first buffer circuit and the role of the proportional resistor achieve accurate replication and calculation of the voltage value; and the voltage reference circuit uses a single-point grounding process in the PCB design, which further ensures the accuracy of the output voltage value.

[0066] Optionally, the current reference circuit includes a second buffer circuit and multiple current circuits, the input end of the second buffer circuit is connected to the power supply circuit, the current circuits are arranged in parallel and the input end of the current circuit is connected to the output end of the second buffer circuit, and the output end of the current circuit is connected to the ground end of the reference chip and the current measurement end of the measurement module.

[0067] In one embodiment, the reference chip may input a 7V voltage signal to the second buffer circuit, and the voltage signal is transmitted to each current circuit by the second buffer circuit.

[0068] Optionally, when the voltage reference circuit and the current reference circuit are connected to the same reference chip, the second buffer circuit includes a sixth operational amplifier U6, the in-phase input terminal of the sixth operational amplifier U6 is connected to the output terminal of the reference chip, and the inverting input terminal is connected to the output terminal of the sixth operational amplifier U6 and the input terminal of the current circuit. Wherein, when the voltage reference circuit and the current reference circuit are connected to different reference chips, the second buffer circuit also includes a sixth resistor R6, the first end of the sixth resistor R6 is connected to the output terminal of the reference chip, and the second end of the sixth resistor R6 is connected to the in-phase input terminal of the sixth operational amplifier U6.

[0069] Optionally, the current reference circuit includes a seventh operational amplifier U7 and a ninth control switch W9, the output end of the current circuit is connected to the in-phase input end of the seventh operational amplifier U7 and the first end of the ninth control switch W9, the inverting input end of the seventh operational amplifier U7 is connected to the ground end of the reference chip and the output end of the seventh operational amplifier U7, and the second end of the ninth control switch W9 is connected to the current measurement end of the measurement module. Whether the current reference circuit is connected to the measurement module is controlled by the ninth control switch W9.

[0070] Optionally, the current circuit includes a circuit control switch and a current adjustment resistor. The first end of the circuit control switch is connected to the output end of the second buffer circuit, the second end of the circuit control switch is connected to the first end of the current adjustment resistor, and the second end of the current adjustment resistor is connected to the ground end of the reference chip and the current measurement end of the measurement module. Different current circuits have different resistance values.

[0071] In one embodiment, the number of current circuits is five, and current signals of 7mA, 70μA, 0.7μA, 7nA, and 70pA are output through five current resistors respectively. The resistance values ​​of the current adjustment resistors in different current circuits are different, and the current circuit is controlled to output a current signal of corresponding magnitude by controlling the opening and closing of the circuit control switch in the current circuit. Specifically, the current adjustment resistor includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5, and the circuit control switch includes a first control switch W1, a second control switch W2, a third control switch W3, a fourth control switch W4, and a fifth control switch W5.

[0072] Optionally, to improve the stability of the current signal output by the current reference circuit, the operational amplifier and switch used in the current reference circuit may be low leakage devices, the resistors in the circuit may be high precision and low temperature drift resistors, and the operational amplifier may be a low bias operational amplifier. Furthermore, the PCB board where the current reference circuit is located adopts a low leakage layout.

[0073] The SMU provided in the present application includes an ADC module, a DAC module, a measurement module, and a calibration module provided with a voltage reference circuit and a current reference circuit. The measurement module is connected to the calibration module, the ADC module, and the DAC module respectively. The calibration module is used to output a reference signal to the measurement module during calibration, and the reference signal includes a voltage signal or a current signal; the measurement module is used to receive the reference signal and transmit the reference signal to the ADC module; the ADC module is used to generate a first measurement result according to the reference signal to calibrate the measurement function of the SMU, and the measurement function calibration is based on the first measurement result and the reference signal; the DAC module is used to send a test signal to the measurement module after the measurement function calibration is completed to calibrate the output function of the SMU, and the calibration of the output function is achieved by the second measurement result and the test signal, and the second measurement result is generated by the ADC module based on the test signal transmitted by the measurement module. The embodiment of the present application can calibrate the measurement function and output function of the SMU through the voltage signal or current signal output by the calibration module in the SMU, improve the accuracy of voltage measurement, current measurement and output signal, so that the device can achieve long-term accurate measurement and accurate signal output in various environments, and improve the reliability of the SMU.

[0074] Based on the same inventive concept, the present application also proposes a self-calibration method for an SMU, wherein the SMU used in the self-calibration method is the SMU described in the above embodiment, such as Figure 6 As shown, the self-calibration method includes:

[0075] S101: Determine the working mode of the measurement module, and control the calibration module to output a reference signal according to the working mode. The reference signal includes a voltage signal or a current signal.

[0076] S102: Using the measurement module to transmit the reference signal to the ADC module, and obtaining a first measurement result of the ADC module in response to the reference signal.

[0077] S103: Calibrate the measurement function of the SMU according to the first measurement result and the reference signal.

[0078] S104: Determine that the measurement function calibration is completed, use the measurement module to transmit the test signal sent by the DAC module to the ADC module, and obtain a second measurement result of the ADC module in response to the test signal.

[0079] S105: Calibrate the output function of the SMU according to the second measurement result and the test signal.

[0080] Optionally, during calibration, the deviation between the measurement result and the value corresponding to the reference signal can be obtained, and the measurement module can be adjusted according to the deviation so that the measurement result output by the adjusted measurement module is consistent with the value of the reference signal. After the calibration of the measurement function is completed, a test signal of a specific value (such as a specific voltage value or a specific current value) can be output to the measurement module through the DAC module, and the measurement module transmits the test signal to the ADC module, and the ADC module outputs the measurement value of the test signal. The output function of the SMU is calibrated according to the deviation between the measurement value and the specific value so that when the calibrated DAC module outputs a signal of a specified value, the measurement value of the signal by the ADC module is consistent with the specified value.

[0081] The terms "first", "second", "third", "fourth", "1", "2", etc. (if any) in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that shown or described in the drawings.

[0082] It should be understood that, although each operation step is indicated by arrows in the flowchart of the embodiment of the present application, the implementation order of these steps is not limited to the order indicated by the arrows. Unless clearly stated herein, in some implementation scenarios of the embodiment of the present application, the implementation steps in each flowchart can be performed in other orders according to demand. In addition, some or all of the steps in each flowchart may include multiple sub-steps or multiple stages based on actual implementation scenarios. Some or all of these sub-steps or stages may be executed at the same time, and each sub-step or stage in these sub-steps or stages may also be executed at different times respectively. In different scenarios of execution time, the execution order of these sub-steps or stages may be flexibly configured according to demand, and the embodiment of the present application does not limit this.

[0083] The above is only an optional implementation method for some implementation scenarios of the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the technical concept of the solution of the present application, other similar implementation methods based on the technical ideas of the present application are also within the protection scope of the embodiments of the present application.

Claims

1. A SMU, characterized in that: It includes an ADC module, a DAC module, a measurement module, and a calibration module provided with a voltage reference circuit and a current reference circuit, wherein the measurement module is connected to the calibration module, the ADC module, and the DAC module respectively, and the calibration module is used to output a reference signal to the measurement module during calibration, wherein the reference signal includes a voltage signal or a current signal; The measuring module is used to receive the reference signal and transmit the reference signal to the ADC module; The ADC module is used to generate a first measurement result according to the reference signal to calibrate the measurement function of the SMU, and the measurement function calibration is implemented based on the first measurement result and the reference signal; The DAC module is used to output a signal through the measurement module and, after the measurement function calibration is completed, send a test signal to the measurement module to calibrate the output function of the SMU. The calibration of the output function is achieved through a second measurement result and the test signal. The second measurement result is generated by the ADC module based on the test signal transmitted by the measurement module.

2. The SMU according to claim 1, characterized in that The calibration module includes a power supply circuit provided with a power supply and a reference chip. The output end of the power supply is connected to the input end of the reference chip. The voltage output end of the reference chip is connected to the input ends of the voltage reference circuit and the current reference circuit. The reference chips connected to the voltage reference circuit and the current reference circuit are the same or different.

3. The SMU according to claim 2, characterized in that The voltage reference circuit and the current reference circuit are connected to the same reference chip, the output end of the voltage reference circuit is connected to the voltage detection end of the measurement module, the first output end of the current reference circuit is connected to the current detection end of the measurement module, and the second output end of the current reference circuit is connected to the ground end of the reference chip.

4. The SMU according to claim 3, characterized in that The power supply circuit includes an eighth control switch and a tenth control switch, the first end of the eighth control switch is connected to the first end of the tenth control switch and the ground end of the reference chip, the second end of the eighth control switch is grounded, and the second end of the tenth control switch is connected to the second output end of the current reference circuit.

5. The SMU according to claim 2, wherein: The voltage reference circuit includes a first buffer circuit, a first voltage circuit and a second voltage circuit, the input end of the buffer circuit is connected to the output end of the power supply circuit, the output end of the buffer circuit is connected to the input end of the first voltage circuit, and the voltage signals output by the first voltage circuit and the second voltage circuit are different; The first voltage circuit comprises a sixth control switch, a first end of the sixth control switch is connected to an input end of the second voltage circuit, and a second end of the sixth control switch is connected to an output end of the second voltage circuit and a voltage measuring end of the measuring module; The second voltage circuit includes a seventh control switch for controlling the on and off of the second voltage circuit, and a second end of the seventh control switch is connected to a voltage measuring end of the measuring module.

6. The SMU according to claim 5, characterized in that The voltage signals output by the first voltage circuit and the second voltage circuit are different. The first voltage circuit also includes a fifteenth resistor, an eighth resistor, and a second operational amplifier. The first end of the fifteenth resistor is connected to the output end of the buffer circuit, the second end of the eighth resistor is grounded, the first end of the eighth resistor is connected to the second end of the fifteenth resistor and the non-inverting input end of the second operational amplifier, and the inverting input end of the second operational amplifier is connected to the input end of the second voltage circuit and the first end of the sixth control switch.

7. The SMU according to claim 2, characterized in that The current reference circuit includes a second buffer circuit and multiple current circuits. The input end of the second buffer circuit is connected to the power supply circuit. The current circuits are arranged in parallel and the input end of the current circuit is connected to the output end of the second buffer circuit. The output end of the current circuit is connected to the ground end of the reference chip and the current measurement end of the measurement module.

8. The SMU according to claim 7, characterized in that The current reference circuit includes a seventh operational amplifier and a ninth control switch. The output end of the current circuit is connected to the non-inverting input end of the seventh operational amplifier and the first end of the ninth control switch. The inverting input end of the seventh operational amplifier is connected to the ground end of the reference chip and the output end of the seventh operational amplifier. The second end of the ninth control switch is connected to the current measurement end of the measurement module.

9. The SMU according to claim 7, wherein: The current circuit includes a circuit control switch and a current adjustment resistor. The first end of the circuit control switch is connected to the output end of the second buffer circuit, the second end of the circuit control switch is connected to the first end of the current adjustment resistor, and the second end of the current adjustment resistor is connected to the ground end of the reference chip and the current measurement end of the measurement module. Different current circuits have different resistance values.

10. A self-calibration method for SMU, characterized in that: For an SMU as claimed in any one of claims 1 to 9, the self-calibration method comprises: Determine the working mode of the measurement module, and control the calibration module to output a reference signal according to the working mode, wherein the reference signal includes a voltage signal or a current signal; Transmitting the reference signal to the ADC module using a measurement module to obtain a first measurement result of the ADC module in response to the reference signal; calibrating a measurement function of the SMU according to the first measurement result and the reference signal; Determine that the measurement function calibration is completed, use the measurement module to transmit the test signal sent by the DAC module to the ADC module, and obtain a second measurement result of the ADC module in response to the test signal; An output function of the SMU is calibrated according to the second measurement result and the test signal.

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