Circuit and method for rapidly monitoring dynamic on-resistance of GaN device before and after short circuit

Abstract

The application belongs to the technical field of semiconductors, and particularly relates to a circuit and method for rapidly monitoring dynamic on-resistance of GaN devices before and after short circuit. The application integrates a test module of dynamic on-resistance on a short circuit test circuit of a conventional GaN HEMT, and the test circuit comprises a driving control module, a control tube Q1, a tube to be tested Q2, a resistance module R, a clamping circuit, a large capacitor C1 and a small capacitor C2. The test method is as follows: the driving control module controls the switching time sequence of the control tube Q1 and the tube to be tested Q2, wherein the control tube Q1 and the tube to be tested Q2 are simultaneously turned on to be powered by a power supply module to perform GaN HEMT device short circuit test in two cases of hard switching failure or load failure; the control tube Q1 is turned off and the tube to be tested Q2 is turned on, and the on-resistance of the device is obtained by monitoring the current on the resistance module R and the voltage on the clamping circuit. According to the technical scheme provided by the application, the dynamic on-resistance value of the tube to be tested Q2 can be extracted within microsecond-level time after the short circuit test of the GaN HEMT device.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and in particular relates to a circuit and method for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit. Background Technology

[0002] With the rapid development of the electronics industry, the requirements for power electronic devices are increasingly trending towards high speed, high density, high integration, and miniaturization. Traditional Si-based devices, limited by the properties of Si materials, struggle to meet the increasingly stringent operating environment requirements. GaN, as a third-generation semiconductor material, with its wider bandgap, higher critical electric field, higher thermal conductivity, higher electron mobility, higher electron saturation velocity, and stronger radiation resistance, is more suitable for fabricating large-scale devices with high voltage, high frequency, high power consumption, and radiation resistance. It is crucial for supporting innovative development fields such as radar, 5G communication, new energy vehicles, high-speed trains, photovoltaics, and smart grids. Under these operating conditions, short-circuit reliability issues arise in GaN devices. In practical applications, due to the presence of short-circuit protection modules, the duration of a single short-circuit pulse is not very long, and the device rarely suffers direct damage. However, after experiencing a short-circuit stress, the electrical characteristics of the GaN device change, which can significantly affect system performance. Currently, the measurement of changes in device characteristics before and after a short circuit is limited to the second level. However, the occurrence and handling of faults at high frequencies and under high conditions should be as short as possible. Therefore, it is particularly important to develop a test method for rapidly detecting changes in device characteristics before and after a short circuit. Summary of the Invention

[0003] To address the aforementioned issues and to more quickly detect the characteristic changes of GaN devices before and after a short circuit, this invention provides a test circuit and method capable of extracting the dynamic on-resistance value of the transistor Q2 under test within microseconds after a short-circuit test of a GaN HEMT device.

[0004] The technical solution of this invention is as follows:

[0005] A circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit includes a power supply, a first capacitor, a second capacitor, a protection module, a first GaN device, a second GaN device, a control drive module, a clamping circuit, and a resistor. The positive plate of the first capacitor is connected to the positive terminal of the power supply, and the negative plate of the first capacitor is connected to the negative terminal of the power supply. The positive plate of the second capacitor is connected to the positive terminal of the power supply via the protection module, and the negative plate of the second capacitor is connected to the negative terminal of the power supply. The drain of the first GaN device is connected to one end of the resistor and the positive plate of the second capacitor. The source of the first GaN device is connected to the other end of the resistor, the drain of the second GaN device, and one end of the clamping circuit. The source of the second GaN device is connected to the other end of the clamping circuit and the negative terminal of the power supply. The control drive module outputs a first control signal and a second control signal, which are respectively connected to the gates of the first and second GaN devices. By controlling the first and second GaN devices, the dynamic on-resistance of the GaN device before and after a short circuit is obtained by testing the current flowing through the resistor and the voltage on the clamping circuit.

[0006] Furthermore, the breakdown voltage of the first GaN device is greater than or equal to the breakdown voltage of the second GaN device.

[0007] Furthermore, the on-resistance of the first GaN device is much smaller than that of the second GaN device.

[0008] Furthermore, the saturation current of the first GaN device is greater than the maximum pulse current of the second GaN device.

[0009] Furthermore, the control drive module can be any one of a function generator, DSP, or FPGA.

[0010] Furthermore, the clamping circuit has a withstand voltage greater than the power supply voltage.

[0011] A method for quickly monitoring the dynamic on-resistance of GaN devices before and after a short circuit:

[0012] When the power is turned on, the first capacitor and the second capacitor are charged to the bus voltage. The control and drive module controls the first GaN device to turn off and the second GaN device to turn on and off continuously. The on-resistance of the second GaN device is obtained by testing the current flowing through the resistor and the voltage on the clamping circuit.

[0013] The control and drive module controls the first GaN device to turn on and the second GaN device to turn on, and performs a short-circuit test on the second GaN device;

[0014] The control and drive module controls the first GaN device to turn off while the second GaN device continues to turn on and off continuously. The on-resistance of the second GaN device after a short-circuit test is then tested.

[0015] The pulse widths of the first control signal and the second control signal issued by the control drive module are inconsistent. When the pulse width of the first control signal is greater than that of the second control signal, a hard switch fault is detected during the short circuit test. When the pulse width of the first control signal is less than that of the second control signal, a load fault is detected during the short circuit test.

[0016] The beneficial effects of this invention are as follows: In traditional short-circuit testing methods, the electrical characteristic testing system and the short-circuit testing system are two independent systems. Monitoring the basic electrical characteristics of the device and applying short-circuit stress require manual switching. Therefore, the interval between monitoring the basic electrical characteristics and applying short-circuit stress is long and inconsistent, leading to significant deviations in the test data. However, this invention controls the switching sequence of the GaN device through a drive control module, automatically switching between short-circuit testing and dynamic on-resistance testing. This greatly reduces the interval monitoring time of the device's electrical characteristics before and after the short-circuit test, allowing for more accurate and stable extraction of the device's electrical parameters and significantly improving data accuracy. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the test circuit proposed in this invention.

[0018] Figure 2 This is a schematic diagram of the gate signal emitted by the drive control module in this invention.

[0019] Figure 3 This is a schematic diagram of the short-circuit waveform of a GaN HEMT device simulating a hard-switching fault according to the present invention.

[0020] Figure 4 This is a schematic diagram of the short-circuit waveform of a GaN HEMT device under load fault simulated in this invention.

[0021] Figure 5 This is a schematic diagram of the voltage waveform measured by the clamping circuit in the test circuit proposed in this invention.

[0022] Figure 6 This is a schematic diagram of the circuit function when performing a short-circuit test on the test circuit proposed in this invention.

[0023] Figure 7 This is a schematic diagram of the circuit function when performing dynamic on-resistance testing on the test circuit proposed in this invention. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings.

[0025] This invention proposes a rapid monitoring circuit for the dynamic on-resistance of GaN devices before and after a short circuit, such as... Figure 1 As shown, its structure includes a high-voltage source U dc1. Energy storage module (divided into large capacitor module C1 and small capacitor module C2), 2. Protection module, R, R resistor module, Q1 control tube, Q2 test tube, 3. Clamping circuit, 1. Control drive module.

[0026] Among them, high voltage source U dc The maximum output voltage should be greater than the bus voltage required for the test; the energy stored in the large capacitor module should be greater than the voltage required for the short-circuit test. The specific capacitance value can be determined according to the following formula: Where ΔU is the acceptable short-circuit voltage drop, tsc is the short-circuit time, and Isc is the short-circuit current; the small capacitor module is recommended to be a parallel connection of small-value MLCC capacitors; the protection module detects the magnitude of the current flowing through it, and disconnects after reaching the set value to isolate the large capacitor module and high-voltage source from the test module to protect the circuit; the shutdown current value set by the protection module should be greater than the maximum pulse current of the test tube and less than the saturation current of the control tube; the resistance module is set according to the current flowing through the test tube when testing the dynamic on-resistance, and the resistance value is generally several hundred Ω. It is recommended to form a resistance module by connecting large resistors in parallel; the on-resistance of the control tube should be much lower than that of the test tube so that the bus voltage is basically applied to the test tube during short-circuit testing. Therefore, GaN tubes with the same low on-resistance can be connected in parallel; the clamping circuit is used to accurately test the voltage at low potentials at the D and S ends of the test tube; the control drive module controls the opening and closing of the control tube and the test tube.

[0027] Example 1: As Figure 1 As shown, when the high-voltage source is turned on to charge the energy storage module, the control drive module simultaneously turns off the control transistor and the test transistor, and the voltage across the energy storage module rises to the same level as the high-voltage source's set voltage. Afterwards, the drive control module turns the control transistor off, and the test transistor continuously turns on and off, as shown... Figure 2 As shown. At this time, the test voltage extracted from the clamping circuit is as follows: Figure 5 Dividing the measured current flowing through the resistance module by the value shown yields the dynamic on-resistance of the current test tube. The equivalent circuit diagram of the test circuit can then be referenced. Figure 7 The control transistor is essentially open-circuited. During the short-circuit test, the drive control module controls both the control transistor and the test transistor to be turned on simultaneously, with PWM1 pulse width greater than PWM2, such as... Figure 2 As shown in the dashed box HSF, the equivalent circuit diagram of the test circuit at this time is as follows. Figure 6 As shown, the control transistor is equivalent to a thick wire with only a small voltage drop across its ends, the resistor module is equivalent to being bypassed, and the voltage on the clamping circuit is the designed clamping voltage. Figure 5 As shown. According to general short-circuit testing, the short-circuit parameter V of the test device is of interest. GS V DS I DS In this invention, the short-circuit test waveform for hard switch faults can be obtained as follows: Figure 3As shown, the gate voltage of the test transistor rises rapidly, turning the test transistor on. Simultaneously, the voltage across the drain and source terminals approaches the bus voltage, with only minor fluctuations (less than 10V) during device turn-on and turn-off. The drain current reaches its maximum pulse current and then decreases. After a short-circuit period roughly the same as the pulse width of PWM1, the gate voltage drops to zero, turning the device off and ending the short-circuit test. The drive control module controls the control transistor to turn off, and the test transistor continuously turns on and off to continue testing the device's dynamic on-resistance. This is equivalent to inserting a short-circuit test into the dynamic on-resistance test. Because the short-circuit test time is short (note that this does not mean the test system can only perform brief short-circuit tests, but rather that the short-circuit withstand time requirement in actual engineering is generally 10 microseconds), the interval between the short-circuit test and the dynamic on-resistance test in this invention is less than the pulse period of PWM2. Therefore, the dynamic on-resistance value of the device after the short-circuit test can be extracted at the microsecond level.

[0028] Example 2: The implementation steps are the same as in Example 1, except for the short-circuit test, where the PWM2 pulse width is greater than that of PWM1. Figure 2 The dashed box FUL indicates the load fault short-circuit test waveform that can be obtained. Figure 4 As shown, the gate voltage of the test tube remained at the turn-on voltage, the drain-source voltage rose from zero and stabilized after approaching the bus voltage, and the drain current waveform was basically consistent with that of a hard-switching fault.

[0029] In the above tests, the two simulated short-circuit fault types can be arbitrarily switched using PWM1 and PWM2 pulse widths generated by the control drive module in this invention. This allows for the characterization of the dynamic on-resistance of the device before and after the two short-circuit tests without manual modification of the test equipment.

[0030] As a supplement, whether the test tube is damaged during testing can be determined by whether the protection module is disconnected or whether the voltage measured by the clamping circuit is zero. Whether the test system is faulty can be determined by whether the voltage measured by the clamping circuit remains at the clamping voltage for an extended period.

Claims

1. A circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit, characterized in that, The system includes a power supply, a first capacitor, a second capacitor, a protection module, a first GaN device, a second GaN device, a control and drive module, a clamping circuit, and a resistor. The positive plate of the first capacitor is connected to the positive terminal of the power supply, and the negative plate of the first capacitor is connected to the negative terminal of the power supply. The positive plate of the second capacitor is connected to the positive terminal of the power supply via the protection module, and the negative plate of the second capacitor is connected to the negative terminal of the power supply. The drain of the first GaN device is connected to one end of the resistor and the positive plate of the second capacitor. The source of the first GaN device is connected to the other end of the resistor, the drain of the second GaN device, and one end of the clamping circuit. The source of the second GaN device is connected to the other end of the clamping circuit and the negative terminal of the power supply. The control and drive module outputs a first control signal and a second control signal, which are respectively connected to the gates of the first and second GaN devices. By controlling the first and second GaN devices, the dynamic on-resistance of the GaN devices before and after a short circuit is obtained by testing the current flowing through the resistor and the voltage on the clamping circuit. Specifically: When the power is turned on, the first capacitor and the second capacitor are charged to the bus voltage. The control and drive module controls the first GaN device to turn off and the second GaN device to turn on and off continuously. The on-resistance of the second GaN device is obtained by testing the current flowing through the resistor and the voltage on the clamping circuit. The control and drive module controls the first GaN device to turn on and the second GaN device to turn on, and performs a short-circuit test on the second GaN device; The control and drive module controls the first GaN device to turn off while the second GaN device continues to turn on and off continuously. The on-resistance of the second GaN device after a short-circuit test is then tested. The pulse widths of the first control signal and the second control signal issued by the control drive module are inconsistent. When the pulse width of the first control signal is greater than that of the second control signal, a hard switch fault is detected during the short circuit test. When the pulse width of the first control signal is less than that of the second control signal, a load fault is detected during the short circuit test.

2. The circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit, as described in claim 1, is characterized in that... The breakdown voltage of the first GaN device is greater than or equal to the breakdown voltage of the second GaN device.

3. The circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit, as described in claim 1, is characterized in that... The on-resistance of the first GaN device is much smaller than that of the second GaN device.

4. The circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit, as described in claim 1, is characterized in that... The saturation current of the first GaN device is greater than the maximum pulse current of the second GaN device.

5. The circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit, as described in claim 1, is characterized in that... The control drive module can be any one of a function generator, DSP, or FPGA.

6. The circuit for rapidly monitoring the dynamic on-resistance of a GaN device before and after a short circuit, as described in claim 1, is characterized in that... The clamping circuit has a withstand voltage greater than the power supply voltage.

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