A power device dynamic threshold voltage Vth measurement system

Abstract

The present invention discloses a power device dynamic threshold voltage Vth measurement system, including: a high-voltage source, a current source, a pressure application time control unit, a device under test, and a threshold voltage switching unit; the current source provides a constant current power supply for the device under test, the high-voltage source provides high-voltage direct current for the device under test, and the threshold voltage switching unit controls the conduction of the device under test. When the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth; the pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time. This solution can measure the value of the power device dynamic threshold voltage Vth, so it can effectively reflect the real-time change of the threshold voltage Vth when the power device switches.

Description

Technical Field

[0001] The present invention relates to the technical field of power device measurement, and particularly to a power device dynamic threshold voltage Vth measurement system. Background Art

[0002] For the existing technologies, currently on the market, when measuring the threshold voltage Vth value of a power device, only a static fixed value can be obtained, which cannot effectively reflect the real-time change of the threshold voltage Vth value when the power device switches, and even less can reflect the offset situation of the threshold voltage Vth value of the power device.

[0003] Therefore, there is an urgent need for a solution that can measure the dynamic threshold voltage Vth value of a power device and effectively reflect the real-time change of the threshold voltage Vth when the power device switches. Summary of the Invention

[0004] The present invention provides a power device dynamic threshold voltage Vth measurement system to solve the above problems existing in the prior art.

[0005] The present invention provides a power device dynamic threshold voltage Vth measurement system, including:

[0006] A high-voltage source, a current source, a pressure application time control unit, a device under test, and a threshold voltage switch unit; the current source provides a constant current power supply for the device under test, the high-voltage source provides high-voltage direct current for the device under test, the threshold voltage switch unit controls the conduction of the device under test, and when the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth; the pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time.

[0007] Preferably, the threshold voltage switch unit includes: a field-effect transistor Q2, a diode D1, a diode D2, and a first PWM signal source; a diode is connected between the source and the drain of the field-effect transistor Q1;

[0008] The output end of the current source is connected to the drain of the device under test via the diode D1, the output end of the current source is respectively connected to the gate of the device under test and the drain of the field-effect transistor Q2 via the diode D2, and the gate of the field-effect transistor Q2 is connected to the first PWM signal source; the first PWM signal source provides a PWM signal for the field-effect transistor Q2.

[0009] Preferably, the pressure application time control unit includes: a field-effect transistor Q1 and a second PWM signal source;

[0010] The gate of the field effect transistor Q1 is connected to the second PWM signal source, and the second PWM signal source provides a PWM signal for the field effect transistor Q1; the second PWM signal source and the first PWM signal source synchronously input PWM signals;

[0011] The source of the field effect transistor Q1 is connected to the drain of the device under test; the drain of the field effect transistor Q1 is connected to the positive pole of the high voltage source; the source of the device under test is connected to the negative pole of the high voltage element;

[0012] A diode is connected between the source and the drain of the field effect transistor Q1.

[0013] Preferably, when the current source is turned on to provide a constant current power supply to the device under test, the field effect transistor Q1 and the field effect transistor Q2 are in the off state. The current source charges the gate of the device under test through the diode D2. When the voltage accumulated at the gate reaches the threshold value Vth, the device under test is turned on; the current source returns to the ground terminal through the diode D1 and the device under test, forming a loop, and the gate voltage of the device under test no longer increases. The measured gate voltage of the device under test is the threshold voltage Vth of the device under test.

[0014] Preferably, the high voltage source applies the required voltage, and synchronously inputs PWM signals to the field effect transistor Q1 and the field effect transistor Q2 through the first PWM signal source and the second PWM signal source respectively; the gate voltage of the device under test decreases, and the device under test is turned off; the application of the voltage source is stopped, and the application time is equal to the positive duty cycle time of the PWM signal. After the PWM signal is turned off, the change of the gate voltage of the device under test is measured to determine the change of the threshold voltage Vth of the gate under different application time conditions or different frequency conditions.

[0015] Preferably, the change of the threshold voltage Vth of the gate under different application time conditions or different frequency conditions includes:

[0016] Before the high voltage source applies the required voltage, the threshold voltage Vth of the gate remains at a first constant value. After the high voltage source applies the required voltage and during the application process, the threshold voltage Vth of the gate remains at a second constant value, and the second constant value is lower than the first constant value;

[0017] After the application process of the high voltage source ends, that is, at the moment when the PWM signal is turned off, the threshold voltage Vth of the gate is at the maximum value. By detecting the value of the threshold voltage Vth of the gate in real time, the change of the threshold voltage Vth from the maximum value to the first constant value during the Vth measurement stage is determined.

[0018] Preferably, by adjusting the application time of the high voltage source, the time required for the threshold voltage Vth to decrease from the maximum value to the first constant value and the change curve are measured.

[0019] Preferably, the current source uses an adjustable constant current power supply to charge the gate of the power device under test;

[0020] The high-voltage source includes: a high-voltage DC input interface, an electrolytic capacitor, and five capacitors connected in parallel. A stable DC voltage is obtained through filtering by the electrolytic capacitor and the capacitors connected in parallel.

[0021] Preferably, the pressure application time control unit uses PWM_INMH1 as the signal input, and uses the first isolation drive chip U1 for isolation drive, and controls the pressure application time between the drain and source of the device under test through the isolation drive chip U1.

[0022] Preferably, the threshold voltage switching unit uses PWM_INM1 as the signal input, and uses the second isolation drive chip to isolate and drive the operation of the device under test at different frequencies; a voltage measurement device is provided between the gate and source of the device under test, and a voltage test device is provided between the drain and source of the device under test, and the voltage between the gate-source and the drain-source is used as the detection point of the threshold voltage Vth of the device under test.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The present invention provides a power device dynamic threshold voltage Vth measurement system, including: a high-voltage source, a current source, a pressure application time control unit, a device under test, and a threshold voltage switching unit; the current source provides a constant current power supply for the device under test, the high-voltage source provides high-voltage direct current for the device under test, the threshold voltage switching unit controls the conduction of the device under test, and when the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth; the pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time.

[0025] This solution can measure the dynamic threshold voltage Vth value of the power device, so it can effectively reflect the real-time change of the threshold voltage Vth when the power device switches. Specifically, different conditions can be changed to measure the change of the threshold voltage Vth value of the power device; the change of the Vth value of the power device under different VDS voltages and different pressure application times can be observed; the change of the threshold voltage Vth value of the power device when it operates at different frequencies can be observed.

[0026] Other features and advantages of the present invention will be described in the following specification, and, in part, will become apparent from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the written specification, claims, and drawings.

[0027] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0028] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0029] Figure 1 is a schematic circuit diagram of a system for measuring the dynamic threshold voltage Vth of a power device in an embodiment of the present invention;

[0030] Figure 2 is a circuit framework diagram of a system for measuring the dynamic threshold voltage Vth of a power device in an embodiment of the present invention;

[0031] Figure 3 is a timing diagram of a single-pulse test of the dynamic threshold voltage Vth in an embodiment of the present invention;

[0032] Figure 4 is a circuit diagram of a current source in an embodiment of the present invention;

[0033] Figure 5 is a circuit diagram of a pressure application time control unit in an embodiment of the present invention;

[0034] Figure 6 is a circuit diagram of a high-voltage source in an embodiment of the present invention;

[0035] Figure 7 is a circuit diagram of a threshold voltage switching unit and a device under test in an embodiment of the present invention. Detailed Embodiments

[0036] The preferred embodiments of the present invention will be described below with reference to the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0037] An embodiment of the present invention provides a system for measuring the dynamic threshold voltage Vth of a power device. Please refer to Figures 1 - 7 as shown. The measurement system includes:

[0038] A high-voltage source, a current source, a pressure application time control unit, a device under test, and a threshold voltage switching unit; the current source provides a constant current power supply for the device under test, the high-voltage source provides a high-voltage direct current for the device under test, the threshold voltage switching unit controls the conduction of the device under test, and when the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth; the pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time.

[0039] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is a high-voltage source, a current source, a pressure application time control unit, a device under test, and a threshold voltage switching unit; The current source provides a constant current power supply for the device under test, the high-voltage source provides high-voltage direct current for the device under test, and the threshold voltage switching unit controls the conduction of the device under test. When the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth; The pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time.

[0040] Specifically, please refer to Figures 2 - 7 as shown in

[0041] Figure 1 In it, module 1 is the current source, module 2 is the pressure application time control unit, module 3 is the high-voltage source, module 4 is the device under test, and module 5 is the threshold voltage switching unit;

[0042] Module 1 is the current source, which provides a constant current power supply for the threshold voltage of module 4, the device under test; Module 2 controls the pressure application time of the drain D and source S of the device under test; Module 3 provides high-voltage direct current (VBUS represents the voltage on the main circuit); Module 4 is the device under test DUT; Module 5 controls the threshold voltage switch of the device under test.

[0043] In the state to be tested, module 1 outputs a constant current source. The field effect transistor Q1 in module 2 and the field effect transistor Q2 in module 5 are turned off. The current source charges the gate G of module 4 (the device under test DUT) through the diode D2. When it reaches the threshold Vth voltage, module 4 conducts. The output of the constant current source of module 1 returns to GND through D1 and the loop of the device under test DUT. The voltage of the gate G of the device under test no longer increases. At this time, the measured voltage of the gate G of the device under test is the threshold voltage;

[0044] When module 3 (VBUS) applies the voltage required for the test, the field effect transistor Q1 in module 2 and the field effect transistor Q2 in module 5 synchronously input PWM signals. The voltage of the gate G of the device under test is pulled down, and the device under test is immediately turned off. The positive duty cycle time of the PWM signal is the pressure application duration of the drain-source voltage (VDS_DUT) of the device under test. Observe the change of the threshold voltage Vth of the device DUT after the PWM signal is turned off.

[0045] In addition, it should be noted that this embodiment provides a method for constructing the relationship between the specific on-resistance and breakdown voltage of the device under test. According to the change law of the threshold voltage Vth and the change law of the specific on-resistance, a breakdown voltage model can be constructed, and based on the breakdown voltage model, the relationship between the threshold voltage and the specific on-resistance of all devices under test can be determined.

[0046] Specifically, the following formula is used to determine the minimum value of the specific on-resistance of the device under test:

[0047]

[0048] Among them, R on represents the specific on-resistance, V DS represents the threshold voltage, W represents the thickness of the P-N junction, b represents the width of the P-N junction, q represents the unit charge amount, N represents the doping concentration of the P-N junction, ε S represents the dielectric constant of silicon, represents the cube of the drain depletion region width, represents the cube of the source depletion region width, μ n represents the electron mobility.

[0049] Therefore, based on the relationship between the minimum value of the specific on-resistance and the threshold voltage, the range of the applied voltage and the adjustment of the applied time are further determined.

[0050] Module 1 is as Figure 4 shown:

[0051] It uses a dedicated adjustable constant current power supply U5 to charge the gate G of the power device under test.

[0052] Module 2 is as Figure 5 shown:

[0053] PWM_INMH1 is the signal input, and U1 is used for isolation drive. On the one hand, it can reduce signal interference, and on the other hand, it can control the applied time of the drain D and the source S of the device under test.

[0054] Module 3 is as Figure 6 shown:

[0055] CN1 is the high-voltage DC input interface, and it obtains a stable DC voltage through filtering by EC1 (electrolytic capacitor), C3, C4, C5, C6, and C7.

[0056] Module 4 and Module 5 are as Figure 7 shown:

[0057] PWM_INM1 is the signal input, and U2 is used for isolation drive of M1. DUT is the power device under test, and VGS_DUT is the detection point of the threshold voltage Vth of the power device DUT under test.

[0058] The beneficial effects of the above technical solution are as follows: The threshold voltage switching unit in the solution provided by this embodiment controls the conduction of the device under test. When the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth. The pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time. This solution can measure the dynamic threshold voltage Vth value of the power device, so it can effectively reflect the real-time change of the threshold voltage Vth when the power device switches. Specifically, different conditions can be changed to measure the change of the threshold voltage Vth value of the power device; the change of the Vth value of the power device under different VDS voltages and different pressure application times can be observed; the change of the threshold voltage Vth value of the power device when it works at different frequencies can be observed.

[0059] In summary, the circuit design of the solution of this application is simple and easy to implement. It can test the dynamic change of the threshold voltage Vth value of the power device when it works at different frequencies in real time. In addition, it can also test the dynamic change of the threshold voltage Vth value of the drain D and source S of the power device when they work at different voltages in real time.

[0060] In another embodiment, the threshold voltage switching unit includes: a field effect transistor Q2, a diode D1, a diode D2, and a first PWM signal source; a diode is connected between the source and drain of the field effect transistor Q1;

[0061] The output end of the current source is connected to the drain of the device under test via the diode D1. The output end of the current source is respectively connected to the gate of the device under test and the drain of the field effect transistor Q2 via the diode D2. The gate of the field effect transistor Q2 is connected to the first PWM signal source; the first PWM signal source provides a PWM signal for the field effect transistor Q2.

[0062] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is that the threshold voltage switching unit includes: a field effect transistor Q2, a diode D1, a diode D2, and a first PWM signal source; a diode is connected between the source and drain of the field effect transistor Q1;

[0063] The output end of the current source is connected to the drain of the device under test via the diode D1. The output end of the current source is respectively connected to the gate of the device under test and the drain of the field effect transistor Q2 via the diode D2. The gate of the field effect transistor Q2 is connected to the first PWM signal source; the first PWM signal source provides a PWM signal for the field effect transistor Q2.

[0064] The beneficial effects of the above technical solution are as follows: The threshold voltage switching unit provided by the solution of this embodiment includes: a field effect transistor Q2, a diode D1, a diode D2, and a first PWM signal source; a diode is connected between the source and drain of the field effect transistor Q1.

[0065] The output terminal of the current source is connected to the drain of the device under test via the diode D1, the output terminal of the current source is connected to the gate of the device under test and the drain of the field effect transistor Q2 respectively via the diode D2, and the gate of the field effect transistor Q2 is connected to the first PWM signal source; the first PWM signal source provides a PWM signal for the field effect transistor Q2.

[0066] In another embodiment, the pressure application time control unit includes: a field effect transistor Q1 and a second PWM signal source.

[0067] The gate of the field effect transistor Q1 is connected to the second PWM signal source, and the second PWM signal source provides a PWM signal for the field effect transistor Q1; the second PWM signal source and the first PWM signal source input PWM signals synchronously.

[0068] The source of the field effect transistor Q1 is connected to the drain of the device under test; the drain of the field effect transistor Q1 is connected to the positive pole of the high-voltage source; the source of the device under test is connected to the negative pole of the high-voltage element.

[0069] A diode is connected between the source and drain of the field effect transistor Q1.

[0070] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is that the pressure application time control unit includes: a field effect transistor Q1 and a second PWM signal source.

[0071] The gate of the field effect transistor Q1 is connected to the second PWM signal source, and the second PWM signal source provides a PWM signal for the field effect transistor Q1; the second PWM signal source and the first PWM signal source input PWM signals synchronously.

[0072] The source of the field effect transistor Q1 is connected to the drain of the device under test; the drain of the field effect transistor Q1 is connected to the positive pole of the high-voltage source; the source of the device under test is connected to the negative pole of the high-voltage element.

[0073] A diode is connected between the source and drain of the field effect transistor Q1.

[0074] The beneficial effects of the above technical solution are as follows: The pressure application time control unit provided by the solution of this embodiment includes: a field effect transistor Q1 and a second PWM signal source.

[0075] The gate of the field effect transistor Q1 is connected to the second PWM signal source, and the second PWM signal source provides a PWM signal for the field effect transistor Q1; the second PWM signal source and the first PWM signal source synchronously input PWM signals;

[0076] The source of the field effect transistor Q1 is connected to the drain of the device under test; the drain of the field effect transistor Q1 is connected to the positive pole of the high voltage source; the source of the device under test is connected to the negative pole of the high voltage element;

[0077] A diode is connected between the source and the drain of the field effect transistor Q1.

[0078] In another embodiment, when the current source is turned on to provide a constant current power supply to the device under test, the field effect transistors Q1 and Q2 are in the off state. The current source charges the gate of the device under test through the diode D2. When the voltage accumulated at the gate reaches the threshold Vth, the device under test is turned on; the current source returns to the ground terminal through the diode D1 and the device under test, forming a loop, and the gate voltage of the device under test no longer increases. The measured gate voltage of the device under test is the threshold voltage Vth of the device under test.

[0079] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is that when the current source is turned on to provide a constant current power supply to the device under test, the field effect transistors Q1 and Q2 are in the off state. The current source charges the gate of the device under test through the diode D2. When the voltage accumulated at the gate reaches the threshold Vth, the device under test is turned on; the current source returns to the ground terminal through the diode D1 and the device under test, forming a loop, and the gate voltage of the device under test no longer increases. The measured gate voltage of the device under test is the threshold voltage Vth of the device under test.

[0080] The beneficial effect of the above technical solution is as follows: When the current source is turned on to provide a constant current power supply to the device under test by adopting the solution provided in this embodiment, the field effect transistors Q1 and Q2 are in the off state. The current source charges the gate of the device under test through the diode D2. When the voltage accumulated at the gate reaches the threshold Vth, the device under test is turned on; the current source returns to the ground terminal through the diode D1 and the device under test, forming a loop, and the gate voltage of the device under test no longer increases. The measured gate voltage of the device under test is the threshold voltage Vth of the device under test.

[0081] In another embodiment, a high-voltage source applies a required voltage, and synchronous PWM signals are input to the field-effect transistor Q1 and the field-effect transistor Q2 through a first PWM signal source and a second PWM signal source respectively; the gate voltage of the device under test is reduced, and the device under test is turned off; the application of the voltage source is stopped, and the application duration is equal to the positive duty cycle time of the PWM signal. After the PWM signal is turned off, the change in the gate voltage of the device under test is measured to determine the change in the threshold voltage Vth of the gate under different application time conditions or different frequency conditions.

[0082] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is that a high-voltage source applies a required voltage, and synchronous PWM signals are input to the field-effect transistor Q1 and the field-effect transistor Q2 through a first PWM signal source and a second PWM signal source respectively; the gate voltage of the device under test is reduced, and the device under test is turned off; the application of the voltage source is stopped, and the application duration is equal to the positive duty cycle time of the PWM signal. After the PWM signal is turned off, the change in the gate voltage of the device under test is measured to determine the change in the threshold voltage Vth of the gate under different application time conditions or different frequency conditions.

[0083] The beneficial effects of the above technical solution are as follows: Adopting the solution provided in this embodiment, a high-voltage source applies a required voltage, and synchronous PWM signals are input to the field-effect transistor Q1 and the field-effect transistor Q2 through a first PWM signal source and a second PWM signal source respectively; the gate voltage of the device under test is reduced, and the device under test is turned off; the application of the voltage source is stopped, and the application duration is equal to the positive duty cycle time of the PWM signal. After the PWM signal is turned off, the change in the gate voltage of the device under test is measured to determine the change in the threshold voltage Vth of the gate under different application time conditions or different frequency conditions.

[0084] In another embodiment, as Figure 3 shown, the change in the threshold voltage Vth of the gate under different application time conditions or different frequency conditions includes:

[0085] Before the high-voltage source applies the required voltage, the threshold voltage Vth of the gate remains at a first constant value. After the high-voltage source applies the required voltage and during the application process, the threshold voltage Vth of the gate remains at a second constant value, and the second constant value is lower than the first constant value;

[0086] After the application process of the high-voltage source ends, that is, at the moment when the PWM signal is turned off, the threshold voltage Vth of the gate is at the maximum value. By detecting the value of the threshold voltage Vth of the gate in real time, the change in the threshold voltage Vth from the maximum value to the first constant value during the Vth measurement stage is determined.

[0087] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is to observe the change of the threshold voltage Vth of the gate under different pressure application times or different frequencies, including:

[0088] Before the high-voltage source applies the required voltage, the threshold voltage Vth of the gate remains at a first constant value. After the high-voltage source applies the required voltage and during the pressure application process, the threshold voltage Vth of the gate remains at a second constant value, and the second constant value is lower than the first constant value;

[0089] After the pressure application process of the high-voltage source ends, that is, at the moment when the PWM signal is turned off, the threshold voltage Vth of the gate is at its maximum value. By detecting the value of the threshold voltage Vth of the gate in real time, the change of the threshold voltage Vth from the maximum value to the first constant value during the Vth measurement stage is determined.

[0090] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, the change of the threshold voltage Vth of the gate under different pressure application times or different frequencies is observed, including:

[0091] Before the high-voltage source applies the required voltage, the threshold voltage Vth of the gate remains at a first constant value. After the high-voltage source applies the required voltage and during the pressure application process, the threshold voltage Vth of the gate remains at a second constant value, and the second constant value is lower than the first constant value;

[0092] After the pressure application process of the high-voltage source ends, that is, at the moment when the PWM signal is turned off, the threshold voltage Vth of the gate is at its maximum value. By detecting the value of the threshold voltage Vth of the gate in real time, the change of the threshold voltage Vth from the maximum value to the first constant value during the Vth measurement stage is determined.

[0093] In another embodiment, by adjusting the pressure application time of the high-voltage source, the time required for the threshold voltage Vth to decrease from the maximum value to the first constant value and the change curve are measured.

[0094] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is to measure the time required for the threshold voltage Vth to decrease from the maximum value to the first constant value and the change curve by adjusting the pressure application time of the high-voltage source.

[0095] The beneficial effects of the above technical solution are as follows: By adopting the solution provided in this embodiment, the time required for the threshold voltage Vth to decrease from the maximum value to the first constant value and the change curve are measured by adjusting the pressure application time of the high-voltage source.

[0096] In another embodiment, the current source uses an adjustable constant current power supply to charge the gate of the power device under test;

[0097] The high-voltage source includes: a high-voltage DC input interface, an electrolytic capacitor, and five capacitors connected in parallel. A stable DC voltage is obtained through filtering by the electrolytic capacitor and the parallel-connected capacitors.

[0098] The working principle of the above technical solution is: The solution adopted in this embodiment is that the current source uses an adjustable constant-current power supply to charge the gate of the power device under test.

[0099] The high-voltage source includes: a high-voltage DC input interface, an electrolytic capacitor, and five capacitors connected in parallel. A stable DC voltage is obtained through filtering by the electrolytic capacitor and the parallel-connected capacitors.

[0100] The beneficial effect of the above technical solution is: The solution provided in this embodiment is that the current source uses an adjustable constant-current power supply to charge the gate of the power device under test.

[0101] The high-voltage source includes: a high-voltage DC input interface, an electrolytic capacitor, and five capacitors connected in parallel. A stable DC voltage is obtained through filtering by the electrolytic capacitor and the parallel-connected capacitors.

[0102] In another embodiment, the pressure application time control unit uses PWM_INMH1 as the signal input, and uses the first isolation drive chip U1 for isolation drive, and controls the pressure application time between the drain and source of the device under test through the isolation drive chip U1.

[0103] The working principle of the above technical solution is: The solution adopted in this embodiment is that the pressure application time control unit uses PWM_INMH1 as the signal input, and uses the first isolation drive chip U1 for isolation drive, and controls the pressure application time between the drain and source of the device under test through the isolation drive chip U1.

[0104] The beneficial effect of the above technical solution is: The solution provided in this embodiment is that the pressure application time control unit uses PWM_INMH1 as the signal input, and uses the first isolation drive chip U1 for isolation drive, and controls the pressure application time between the drain and source of the device under test through the isolation drive chip U1.

[0105] In another embodiment, the threshold voltage switching unit uses PWM_INM1 as the signal input, and uses the second isolation drive chip to isolate and drive the operation of the device under test at different frequencies; a voltage measurement device is provided between the gate and source of the device under test, and a voltage test device is provided between the drain and source of the device under test, and the gate-source and drain-source are used as the detection points for the threshold voltage Vth of the device under test.

[0106] The working principle of the above technical solution is as follows: The solution adopted in this embodiment is that the threshold voltage switching unit uses PWM_INM1 as the signal input, and the second isolation driving chip is used to isolate and drive the device under test to work at different frequencies; a voltage measuring device is arranged between the gate and the source of the device under test, and a voltage testing device is arranged between the drain and the source of the device under test. The voltage between the gate and the source and the voltage between the drain and the source are used as the detection points of the threshold voltage Vth of the device under test.

[0107] The beneficial effects of the above technical solution are as follows: The solution provided in this embodiment is that the threshold voltage switching unit uses PWM_INM1 as the signal input, and the second isolation driving chip is used to isolate and drive the device under test to work at different frequencies; a voltage measuring device is arranged between the gate and the source of the device under test, and a voltage testing device is arranged between the drain and the source of the device under test. The voltage between the gate and the source and the voltage between the drain and the source are used as the detection points of the threshold voltage Vth of the device under test.

[0108] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A dynamic threshold voltage Vth measurement system for a power device, characterized in that Comprising: A high-voltage source, a current source, a pressure application time control unit, a device under test, and a threshold voltage switching unit; the current source provides a constant current power supply for the device under test, the high-voltage source provides high-voltage direct current for the device under test, the threshold voltage switching unit controls the conduction of the device under test, and when the device under test conducts, the gate voltage of the device under test is the threshold voltage Vth; the pressure application time control unit determines the change of the threshold voltage Vth under different pressure application time conditions or different frequency conditions by controlling the pressure application time. The threshold voltage switching unit includes: a field-effect transistor Q2, a diode D1, a diode D2, and a first PWM signal source; a diode is connected between the source and the drain of the field-effect transistor Q1. The output terminal of the current source is connected to the drain of the device under test via the diode D1, the output terminal of the current source is respectively connected to the gate of the device under test and the drain of the field-effect transistor Q2 via the diode D2, and the gate of the field-effect transistor Q2 is connected to the first PWM signal source; the first PWM signal source provides a PWM signal for the field-effect transistor Q2. The pressure application time control unit includes: a field-effect transistor Q1 and a second PWM signal source. The gate of the field-effect transistor Q1 is connected to the second PWM signal source, and the second PWM signal source provides a PWM signal for the field-effect transistor Q1; the second PWM signal source and the first PWM signal source synchronously input PWM signals. The source of the field-effect transistor Q1 is connected to the drain of the device under test; the drain of the field-effect transistor Q1 is connected to the positive pole of the high-voltage source; the source of the device under test is connected to the negative pole of the high-voltage source.

2. The dynamic threshold voltage Vth measurement system for a power device according to claim 1, wherein When the current source is turned on to provide a constant current power supply for the device under test, the field-effect transistor Q1 and the field-effect transistor Q2 are in the off state, and the current source charges the gate of the device under test through the diode D2. When the voltage accumulated at the gate reaches the threshold Vth, the device under test conducts; the current source returns to the ground terminal through the diode D1 and the device under test to form a loop, and the gate voltage of the device under test no longer increases. The measured gate voltage of the device under test is the threshold voltage Vth of the device under test.

3. A dynamic threshold voltage Vth measurement system for a power device according to claim 2, characterized in that, The high-voltage source applies the required voltage, and synchronously inputs PWM signals to the field-effect transistor Q1 and the field-effect transistor Q2 through the first PWM signal source and the second PWM signal source respectively; the gate voltage of the device under test decreases, and the device under test turns off; the pressure application of the voltage source is stopped, and the pressure application duration is equal to the positive duty cycle time of the PWM signal. After the PWM signal is turned off, the change of the gate voltage of the device under test is measured to determine the change of the threshold voltage Vth of the gate under different pressure application time conditions or different frequency conditions.

4. A dynamic threshold voltage Vth measurement system for a power device according to claim 3, characterized in that, The change of the threshold voltage Vth of the gate under different pressure application time conditions or different frequency conditions includes: Before the high-voltage source applies the required voltage, the threshold voltage Vth of the gate remains at a first constant value. After the high-voltage source applies the required voltage and during the pressure application process, the threshold voltage Vth of the gate remains at a second constant value, and the second constant value is lower than the first constant value. After the pressure application process of the high-voltage source ends, that is, at the moment when the PWM signal is turned off, the threshold voltage Vth of the gate is at its maximum value. By detecting the value of the threshold voltage Vth of the gate in real time, the change of the threshold voltage Vth from the maximum value to the first constant value during the Vth measurement stage is determined.

5. A dynamic threshold voltage Vth measurement system for a power device according to claim 4, wherein By adjusting the pressure application time of the high-voltage source, the time required for the threshold voltage Vth to decrease from the maximum value to the first constant value and the change curve are measured.

6. The dynamic threshold voltage Vth measurement system for a power device according to claim 1, wherein, The current source uses an adjustable constant-current power supply to charge the gate of the power device under test; The high-voltage source includes: a high-voltage DC input interface, an electrolytic capacitor, and five capacitors connected in parallel. A stable DC voltage is obtained through filtering by the electrolytic capacitor and the capacitors connected in parallel.

7. A dynamic threshold voltage Vth measurement system for a power device according to claim 1, characterized in that The pressure application time control unit uses PWM_INMH1 as the signal input, and uses the first isolation drive chip U1 for isolation drive. The pressure application time between the drain and source of the device under test is controlled through the isolation drive chip U1.

8. A dynamic threshold voltage Vth measurement system for a power device according to claim 1, characterized in that, The threshold voltage switch unit uses PWM_INM1 as the signal input, and uses the second isolation drive chip to isolate and drive the operation of the device under test at different frequencies; a voltage measurement device is set between the gate and source of the device under test, and a voltage test device is set between the drain and source of the device under test. The points between the gate-source and drain-source are used as the detection points for the threshold voltage Vth of the device under test.

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