Soft-cut measurement circuit and measurement method of dynamic resistance of GaN power tube

Abstract

The present invention provides a soft-cut measurement circuit and method for the dynamic resistance of a gallium nitride power tube, comprising: a main circuit connected between the drain and source of the gallium nitride power tube to be measured, the main circuit comprising a high-voltage output circuit and a low-voltage output circuit in parallel; a high-speed drive circuit that provides a drive voltage to the gate of the gallium nitride power tube to be measured; a synchronous program-controlled circuit that provides synchronous control signals of set timings for the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit, respectively, and controls the drive voltage, high voltage and low voltage to be synchronously supplied and disconnected according to the timing; a voltage sampling circuit that is connected in parallel to the drain and source of the gallium nitride power tube to be measured. The present invention can realize rapid high-low voltage switching, and supports synchronous control of multiple timings, and can effectively measure the dynamic resistance of the gallium nitride power tube under dynamic working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit measurement, and in particular to a soft-cut measurement circuit and a measurement method for the dynamic resistance of a gallium nitride power tube. Background Art

[0002] Gallium nitride (GaN) is a new type of semiconductor material. It has the characteristics of large bandgap, high thermal conductivity, high temperature resistance, radiation resistance, acid and alkali resistance, high strength and high hardness. In the early days, it was widely used in new energy vehicles, rail transportation, smart grid, semiconductor lighting, and new generation mobile communications. It is known as the third generation of semiconductor materials. With the cost of technological breakthroughs under control, gallium nitride is currently also widely used in consumer electronics and other fields, and chargers are one of them. With the increase in demand for gallium nitride and more and more applications, the measurement of gallium nitride is becoming more and more important. The measurement of gallium nitride is divided into two categories: static parameters and dynamic parameters.

[0003] Static parameters mainly refer to the related parameters that are inherent in themselves and have nothing to do with their working conditions, including: gate-level turn-on voltage, gate-level breakdown voltage, collector-emitter withstand voltage, collector-emitter leakage current, parasitic capacitance (input capacitance, transfer capacitance, output capacitance), and measurement of the related characteristic curves of the above parameters.

[0004] The dynamic parameter mainly refers to the dynamic on-resistance of the GaN power tube under dynamic working conditions. Due to the traps in the GaN power tube structure and the need to design a longer depletion region length to adapt to the high-voltage breakdown voltage, when the device is turned on immediately after the high-voltage blocking state, the actual channel electrons will be captured and will not participate in the conduction. This will cause the GaN power tube to have a higher on-resistance under dynamic working conditions than under static conditions. The dynamic on-resistance, i.e., dynamic resistance, is of great significance for studying the working characteristics of the GaN power tube. However, in the prior art, there is no simple and effective measurement circuit that can measure the dynamic resistance of the GaN power tube to reflect the characteristics of the GaN power tube under dynamic working conditions. Therefore, it is necessary to design a measurement circuit to effectively measure the dynamic resistance of the GaN power tube. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide a soft-cut measurement circuit and measurement method for the dynamic resistance of a gallium nitride power tube. By designing a soft-cut measurement circuit that can quickly switch between high and low voltages and support multiple timing synchronous programming, the dynamic resistance of the gallium nitride power tube under dynamic working conditions can be effectively measured.

[0006] The technical solution adopted by the present invention is a soft-cut measurement circuit of the dynamic resistance of a gallium nitride power tube, comprising:

[0007] A main circuit connected between the drain and source of the GaN power tube under test, the main circuit comprising a high-voltage output circuit and a low-voltage output circuit connected in parallel, the high-voltage output circuit is used to provide a high voltage between the drain and source of the GaN power tube through the main circuit, and the low-voltage output circuit is used to provide a low voltage between the drain and source of the GaN power tube through the main circuit;

[0008] A high-speed driving circuit that provides driving voltage to the gate of the GaN power tube under test;

[0009] A synchronous program-controlled circuit provides synchronous control signals of set timing for the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit, respectively, and controls the drive voltage, high voltage and low voltage to be synchronously supplied and disconnected according to the timing;

[0010] The voltage sampling circuit is connected in parallel to the drain and source of the GaN power tube under test.

[0011] From the above, the present invention outputs a synchronous control signal of a set timing through a synchronous program-controlled circuit to control the high-voltage output circuit, the low-voltage output current and the high-speed drive circuit in the soft-cut measurement circuit to be turned on in sequence according to the set timing, and measures the voltage value and current value of the gallium nitride power tube at each timing, thereby calculating the resistance value corresponding to each timing. The present invention supports the synchronization of control signals and the processing functions of hardware data, and realizes the fast high-low voltage switching measurement between the drain and the source of the gallium nitride power tube, thereby effectively measuring the dynamic resistance of the gallium nitride power tube under dynamic working conditions.

[0012] Preferably, the high voltage output circuit comprises:

[0013] A high voltage source, a first switch and a first resistor connected in series in sequence;

[0014] The first switch receives a synchronous control signal provided by the synchronous program-controlled circuit to be turned on or off.

[0015] From the above, the high voltage source can be used to provide a voltage not higher than 1000V, and its maximum current capacity is 10mA. The first switch can receive a synchronous control signal to control the opening or closing of the high voltage source. The first resistor is used to achieve current clamping of the high voltage source when the high voltage circuit switches to the low voltage circuit.

[0016] Preferably, the voltage sampling circuit comprises:

[0017] A voltmeter and a high voltage clamp circuit connected in series.

[0018] From the above, the voltage sampling circuit can collect the voltage across the GaN power tube in real time through a high-precision voltmeter, and the high-voltage clamping circuit can clamp the high voltage at its drain when the GaN power tube under test is turned off to protect the high-precision voltmeter from being damaged by the high voltage.

[0019] Preferably, the low voltage output circuit comprises:

[0020] A low voltage source, which is connected to the drain and source of the GaN power tube under test through a four-wire Kelvin circuit;

[0021] The low voltage source is connected to the drain of the GaN power tube under test through a third switch connected in series via the Force_High line of the four-wire Kelvin circuit; the low voltage source is also connected to the drain of the GaN power tube under test through a Sense_High line of the four-wire Kelvin circuit connected in series via the high voltage clamping circuit, and the third switch receives a synchronous control signal provided by the synchronous program control circuit to be turned on or off;

[0022] The Force_Low line and the Sense_Low line of the four-wire Kelvin circuit are respectively connected between the negative output terminal of the low-voltage source and the source electrode of the gallium nitride power tube to be tested.

[0023] As described above, the high-voltage output circuit provides high voltage to the drain and source of the tested gallium nitride power tube, so that it is in a high-voltage environment for a period of time, and then the high voltage between the drain and source of the tested gallium nitride power tube is quickly switched to low voltage by the low-voltage output circuit, and then the current value and voltage value of the tested gallium nitride power tube are measured to obtain its resistance value change parameters under dynamic working voltage. The low-voltage output circuit is connected to the drain and source of the tested gallium nitride power tube through a four-wire Kelvin circuit (Force_High line, Sense_High line, Force_Low line, Sense_Low line), wherein the Force_High line (or high-end drive current line) of the four-wire Kelvin circuit is connected to the drain of the tested gallium nitride power tube through a third switch, and the third switch is used to isolate the high-voltage source and the low-voltage source, and the Sense_High line (or high-end sensing voltage line) of the four-wire Kelvin circuit is connected to the drain of the tested gallium nitride power tube after being connected in series with the high-voltage clamping circuit, so as to provide low voltage for the tested gallium nitride power tube.

[0024] Preferably, the low voltage output circuit further includes a reverse current suppression circuit connected in parallel to both ends of the third switch, including: a second resistor and a fourth switch connected in series;

[0025] The fourth switch receives a synchronous control signal provided by the synchronous program-controlled circuit to be turned on or off.

[0026] As described above, the second resistor is a shunt resistor. By controlling the on or off of the fourth switch, the switching speed from high voltage to low voltage can be reduced to reduce the reverse current flowing to the drain of the tested gallium nitride power tube.

[0027] Preferably, a second switch is connected in series between the Force_High line and the Sense_High line, and the second switch receives a synchronous control signal provided by the synchronous program-controlled circuit to be turned on or off to control a short circuit or an open circuit between the Force_High line and the Sense_High line.

[0028] From the above, when the high-voltage output circuit applies high voltage to the drain and source of the tested gallium nitride power tube, the low-voltage output circuit is in a disconnected state. Before the high voltage is switched to the low voltage, the second switch needs to be turned on to ensure that when the high voltage is switched to the low voltage, the Kelvin circuit at the output end of the low-voltage source is short-circuited and reaches the preset low voltage value in advance. Otherwise, if the Kelvin circuit at the output end of the low-voltage source is in an open-circuit state, the low-voltage source needs an adjustment time of about 20ms to reach the preset low voltage value.

[0029] Based on the above-mentioned soft-cut measurement circuit of the dynamic resistance of the gallium nitride power tube, the present invention also provides a method for measuring the dynamic resistance of the gallium nitride power tube, comprising the steps of:

[0030] A. Provide synchronous control signals of set timing to the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit respectively through the synchronous program control circuit, control the drive voltage provided by the high-speed drive circuit to the gate of the tested GaN power tube, the high voltage provided by the high-voltage output circuit to the drain and source of the GaN power tube, and the low voltage provided by the low-voltage output circuit to the drain and source of the GaN power tube to be synchronously supplied and disconnected according to the timing;

[0031] B. Obtaining current values ​​and voltage values ​​corresponding to each timing through a low-voltage output circuit and a voltage sampling circuit;

[0032] C. Calculate the corresponding resistance values ​​according to the current values ​​and voltage values ​​corresponding to the respective time sequences, and obtain the parameters of the dynamic resistance of the measured gallium nitride power tube.

[0033] From the above, the measurement method realizes the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit to be turned on and off according to the set timing through the synchronous control signal provided by the synchronous programmable circuit, and simultaneously measures the voltage value and the current value of the gallium nitride power tube synchronously. According to Ohm's law, the resistance value at each timing can be calculated using the measured voltage value and current value to obtain the parameters of the dynamic resistance of the measured gallium nitride power tube.

[0034] Preferably, step C further includes:

[0035] Whether the tested GaN power tube is normal is determined according to whether the characteristic curve corresponding to the parameter of the dynamic resistance conforms to the characteristic curve corresponding to the normal GaN power tube.

[0036] From the above, according to the characteristics of gallium nitride materials, the on-resistance of a normal gallium nitride power tube is small under low-voltage working state. When a high voltage is applied to the gallium nitride power tube for a period of time and then it is switched to a low-voltage working state, its on-resistance will increase. Therefore, according to this characteristic, it can be judged whether the measurement result is correct, thereby determining whether the measured gallium nitride power tube is normal.

[0037] Preferably, the synchronization control signal for setting the timing includes:

[0038] Control the high-speed driving circuit to drive the tested gallium nitride power tube to conduct and control the low-voltage output circuit to provide a low voltage between the drain and the source of the gallium nitride power tube, the duration is T1;

[0039] The high-speed driving circuit is controlled to drive the tested gallium nitride power tube to be disconnected and the high-voltage output circuit is controlled to provide high voltage between the drain and the source of the gallium nitride power tube, the duration is T2, and T2>T1.

[0040] From the above, in the present invention, by alternately outputting low voltage and high voltage between the drain and source of the GaN power tube under test, the GaN power tube is placed under a dynamic operating voltage, thereby measuring its resistance value under the dynamic operating voltage to obtain the parameters of its dynamic resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The circuit schematic diagram of the soft-cut measurement circuit of the dynamic resistance of the gallium nitride power tube of the present invention;

[0042] Figure 2 This is a flow chart of a method for measuring the dynamic resistance of a gallium nitride power tube according to the present invention;

[0043] Figure 3 A schematic diagram of waveforms of various circuit parts under the timing setting of the present invention;

[0044] Figure 4 It is a schematic diagram of the dynamic resistance characteristic curve of the gallium nitride power tube of the present invention. DETAILED DESCRIPTION

[0045] Refer to the following Figure 1-Figure 4 The specific implementation of the soft-cut measurement circuit of the dynamic resistance of the gallium nitride power tube according to the present invention is described in detail.

[0046] like Figure 1 The figure shows a circuit schematic diagram of a soft-cut measurement circuit of a dynamic resistance of a gallium nitride power tube according to the present invention. The soft-cut measurement circuit includes:

[0047] The synchronous program control circuit (not shown in the figure) can be implemented by a programmable FPGA chip, which can output a synchronous control signal with a set timing through programming control, so that the soft-cut measurement circuit of the present invention is synchronously turned on or off, and the voltage and current values ​​of the gallium nitride power tube are synchronously measured each time it is turned on;

[0048] A high-voltage source VI1, wherein a positive output terminal of the high-voltage source VI1 is connected in series with a MOS switch K1 and a resistor R1 and then connected to the drain (D) of the GaN power tube under test, wherein the MOS switch K1 receives a synchronous control signal CTRL1 provided by a synchronous program control circuit, and the resistance value of the resistor R1 is 1000 ohms, which can be used to achieve current clamping at the output terminal of the high-voltage source when switching from high voltage to low voltage; and a negative output terminal of the high-voltage source VI1 is connected to the source (S) of the GaN power tube under test;

[0049] A low voltage source VI2, whose output end performs low voltage output and current measurement through a four-wire Kelvin circuit, wherein the four-wire Kelvin circuit includes a driving current line Force_High and a sensing voltage line Sense_High connected to the positive output end of the low voltage source VI2, and a driving current line Force_Low and a sensing voltage line Sense_Low connected to the negative output end of the low voltage source VI2; wherein a MOS switch K3 is connected in series to the driving current line Force_High and then connected to the drain (D) of the gallium nitride power tube to be measured, and the MOS switch K3 receives a synchronous control signal CTRL3 provided by a synchronous program control circuit, and can be used to achieve isolation between the low voltage source VI2 and the high voltage source VI1 to protect the low voltage source VI2, and at the same time, its fast conduction capability can enable the low voltage provided by the low voltage source VI2 to be quickly established to the drain (D) of the gallium nitride power tube to be measured, and a series MOS switch K4 and a resistor R2 are also connected in parallel at both ends of the MOS switch K3, and the MOS switch K4 receives a synchronous control signal CTRL4 provided by the synchronous program control circuit, and can be used to Reduce the switching speed from high voltage to low voltage. The resistor R2 is a shunt resistor, which can be used to reduce the reverse current flowing to the drain of the GaN power tube under test. The sensing voltage line Sense_High is connected in series with the attenuator in the voltage sampling circuit described later and then connected to the drain (D) of the GaN power tube under test, providing a low voltage to the drain (D) of the GaN power tube under test. A MOS switch K2 is also connected in series between the driving current line Force_High and the sensing voltage line Sense_High. The MOS switch K2 receives a synchronous control signal CTRL2 provided by a synchronous program control circuit. When the high voltage is continuously applied to the GaN power tube under test, the MOS switch K3 is in an off state. At this time, the MOS switch K2 is turned on to short-circuit the Kelvin circuit of the low voltage source VI2, so that the low voltage source VI2 can reach the preset low voltage value in advance, thereby avoiding that when the high voltage is switched to the low voltage, the high voltage will cause a certain impact on the low voltage source VI2 at the moment of switching. The low voltage source VI2 needs an adjustment time of about 20ms to reach the preset low voltage value.

[0050] A driver Driver, whose output ends are respectively connected to the gate (G) and source (S) of the GaN power tube under test, and the driver Driver receives the synchronous control signal CTRL0 provided by the synchronous program control circuit, and under the control of the synchronous control signal CTRL0, outputs a high-speed driving signal, i.e., a driving voltage, to the GaN power tube under test to control the conduction or shutdown thereof;

[0051] A voltage sampling circuit is connected in parallel to the drain (D) and source (S) of the GaN power tube, and includes a high-precision voltmeter V1 and an attenuator connected in series. The Sense_High of the above-mentioned four-wire Kelvin circuit is connected in series with the attenuator to provide a low voltage to the GaN power tube under test. The high-precision voltmeter V1 collects the voltage values ​​of the GaN power tube corresponding to each timing in real time under the control of the synchronous control signal of the set timing provided by the synchronous program control circuit. The attenuator mainly plays the role of high-voltage clamping protection in the circuit. When the GaN power tube under test is turned off, the high voltage of its drain is clamped to protect the high-precision voltmeter and the low-voltage source VI2 from being damaged by the high voltage.

[0052] Under the above-mentioned timing setting, the synchronous control signal logic provided by the synchronous program control circuit is:

[0053] When the high voltage source applies high voltage to the GaN power tube under test, the driver does not output the driving voltage, and the GaN power tube under test does not conduct;

[0054] When the low voltage source is turned on, the high voltage applied to the GaN power tube under test is switched to low voltage, and the driver Driver outputs a driving voltage to drive the GaN power tube under test to turn on. At the same time, the voltage sampling circuit and the low voltage source VI2 synchronously measure the voltage and current values;

[0055] The high pressure and low pressure mentioned above are applied at intervals, and the duration of the low pressure application is much shorter than the duration of the high pressure application. Generally, the duration of the low pressure is 5ms, and the duration of the high pressure is 100ms.

[0056] like Figure 2 As shown, when the dynamic resistance of the gallium nitride power tube is measured according to the above-mentioned soft-cut measurement circuit, the following steps are included:

[0057] S100: providing synchronous control signals of set timing to the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit respectively through the synchronous program control circuit, controlling the drive voltage provided by the high-speed drive circuit to the gate of the tested GaN power tube, the high voltage provided by the high-voltage output circuit to the drain and source of the GaN power tube, and the low voltage provided by the low-voltage output circuit to the drain and source of the GaN power tube to be synchronously supplied and disconnected according to the timing;

[0058] like Figure 3The waveform diagram of each circuit part under the set timing of the synchronous program-controlled circuit output is shown. Under the set timing, the synchronous program-controlled circuit provides synchronous control signals to the high-speed drive circuit, the high-voltage output circuit, and the low-voltage output circuit respectively to control their conduction or disconnection under the set timing. In the present invention, the switching from high voltage to low voltage of the soft-cut measurement circuit is mainly realized by the conduction or disconnection of the low-voltage output circuit. In actual measurement, the switch K1 of the high-voltage output circuit can always remain in the on state. Specifically, a complete timing synchronous control cycle is as follows:

[0059] At time t1, the driver Driver is controlled to output a 5V driving voltage to the gate (G) of the GaN power tube under test, driving it to turn on, turning on switches K1 and K3, and turning off switches K2 and K4. At this time, the high voltage 500V output by the high voltage source VI1 is pulled down by the turned-on switch K3, and the voltage applied to the GaN power tube under test is a low voltage of 0.1V, which is maintained for 5ms until time t1';

[0060] At time t1', the driver Driver is controlled to disconnect the 5V driving voltage output to the gate (G) of the GaN power tube under test, driving it to disconnect, turning on switches K1 and K2, and turning off switches K3 and K4. At this time, the high voltage 500V output by the high voltage source VI1 is applied to the GaN power tube under test, the low voltage source is isolated from the high voltage source, and the switch K2 is turned on to short-circuit the driving current line Force_High and the sensing voltage line Sense_High of the Kelvin circuit. The low voltage source reaches the preset voltage value in advance through the short-circuited Kelvin circuit and maintains the high voltage state for 100ms until time t2;

[0061] At time t2, the driver Driver is controlled to output a 5V driving voltage to the gate (G) of the GaN power tube under test, driving it to turn on, turning on switches K1 and K4, and turning off switches K2 and K3. Switch K4 and resistor R2 can reduce the reverse current flowing to the GaN power tube under test at the moment of switching from high voltage to low voltage; then switches K1 and K3 are turned on, switches K2 and K4 are turned off, and the voltage applied to the GaN power tube under test is pulled down to a low voltage of 0.1V again, and the low voltage state is maintained for 5ms until time t2'.

[0062] S200: obtaining current values ​​and voltage values ​​corresponding to each time sequence through a low voltage output circuit and a voltage sampling circuit;

[0063] In this step, the voltage sampling circuit and the low voltage source VI2 are used to synchronously measure and obtain the voltage and current values ​​corresponding to the low voltage duration in each time sequence;

[0064] Among them, the waveform of the current value IC during each low voltage duration measured by the low voltage source VI2 is as follows: Figure 3As shown, according to the current value IC measured by the low voltage source VI2 and the voltage measured by the voltmeter V1, the resistance value of the tested GaN power tube at each timing can be calculated.

[0065] S300: Calculating corresponding resistance values ​​according to the current values ​​and voltage values ​​corresponding to the respective time sequences, and obtaining parameters of the dynamic resistance of the measured GaN power tube;

[0066] S400: determining whether the tested GaN power tube is normal according to whether the characteristic curve corresponding to the parameter of the dynamic resistance conforms to the characteristic curve corresponding to the normal GaN power tube;

[0067] like Figure 4 The figure shows the dynamic resistance characteristic curve of the GaN power tube, where RON1 and RON2 are the corresponding Figure 3 The measurement results of the resistance value RON under the timing shown in FIG. 1 and FIG. 2 can be integrated to generate the following Figure 4 The characteristic curve corresponding to the dynamic resistance parameter of the GaN material, according to the characteristics of the GaN material, the normal GaN power tube has a small on-resistance in the low-voltage working state. After a period of high voltage is applied to its drain and source, according to its characteristics, in the next low-voltage operation state, its on-resistance will increase. This increase process may last for several cycles of high and low voltage switching, and then the area will be stable; therefore, according to the dynamic resistance characteristic curve obtained by the soft-cut measurement circuit, it can be judged whether the GaN power tube meets its characteristics. If it meets, it is judged to be normal, and if it does not meet, it is judged to be abnormal;

[0068] from Figure 4 It can be seen from the change curve that at time T1 (t1-t1'), the resistance value RON1 of the GaN power tube in the on state is low, and then at time T2 (t2-t2'), the resistance value RON2 of the GaN power tube in the on state begins to increase. From the measurement results, it can be concluded that:

[0069] RON1 <RON2;

[0070] ((RON2-RON1) / RON1)*100%>x%;

[0071] Wherein, x% is the floating limit value (limit) proposed by the designer of the GaN power tube, which is used to reflect the dynamic parameter changes of the GaN power tube under the dynamic working state;

[0072] According to the measurement result, it can be determined that the performance of the above-mentioned gallium nitride power tube meets its characteristics and is judged to be in a normal state.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A soft-cut measurement circuit for the dynamic resistance of a gallium nitride power tube, characterized in that: include: A main circuit connected between the drain and source of the GaN power tube under test, the main circuit comprising a high-voltage output circuit and a low-voltage output circuit connected in parallel, the high-voltage output circuit is used to provide a high voltage between the drain and source of the GaN power tube through the main circuit, and the low-voltage output circuit is used to provide a low voltage between the drain and source of the GaN power tube through the main circuit; A high-speed driving circuit that provides driving voltage to the gate of the GaN power tube under test; A synchronous program-controlled circuit provides synchronous control signals of set timing for the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit, respectively, and controls the drive voltage, the high voltage and the low voltage to be turned on or off according to the timing; A voltage sampling circuit is connected in parallel to the drain and source of the GaN power tube to be tested, and the voltage sampling circuit includes a voltmeter and a high-voltage clamping circuit connected in series; The low-voltage output circuit includes a low-voltage source, which is connected to the drain and source of the gallium nitride power tube under test through a four-wire Kelvin circuit; wherein the low-voltage source is connected to the drain of the gallium nitride power tube under test after being connected in series with a third switch through the Force_High line of the four-wire Kelvin circuit; the low-voltage source is also connected to the drain of the gallium nitride power tube under test after being connected in series with the high-voltage clamping circuit through the Sense_High line of the four-wire Kelvin circuit, and the third switch receives a synchronous control signal provided by the synchronous program control circuit to be turned on or off; the Force_Low line and the Sense_Low line of the four-wire Kelvin circuit are respectively connected between the negative output end of the low-voltage source and the source of the gallium nitride power tube under test.

2. The soft-cut measurement circuit according to claim 1, characterized in that: The high voltage output circuit comprises: A high voltage source, a first switch and a first resistor connected in series in sequence; The first switch receives a synchronous control signal provided by the synchronous program-controlled circuit to be turned on or off.

3. The soft-cut measurement circuit according to claim 1, characterized in that: The low voltage output circuit further includes a reverse current suppression circuit connected in parallel to both ends of the third switch, including: a second resistor and a fourth switch connected in series; The fourth switch receives a synchronous control signal provided by the synchronous program-controlled circuit to be turned on or off.

4. The soft-cut measurement circuit according to claim 1, characterized in that: A second switch is connected in series between the Force_High line and the Sense_High line. The second switch receives a synchronous control signal provided by the synchronous program control circuit to be turned on or off, so as to control a short circuit or an open circuit between the Force_High line and the Sense_High line.

5. A method for measuring the dynamic resistance of a gallium nitride power tube based on the soft-cut measurement circuit according to any one of claims 1 to 4, characterized in that: Includes steps: A. Provide synchronous control signals of set timing to the high-speed drive circuit, the high-voltage output circuit and the low-voltage output circuit respectively through the synchronous program control circuit, control the drive voltage provided by the high-speed drive circuit to the gate of the tested GaN power tube, the high voltage provided by the high-voltage output circuit to the drain and source of the GaN power tube, and the low voltage provided by the low-voltage output circuit to the drain and source of the GaN power tube to be turned on or off according to the timing; B. Obtaining current values ​​and voltage values ​​corresponding to each timing through a low-voltage output circuit and a voltage sampling circuit; C. Calculate the corresponding resistance values ​​according to the current values ​​and voltage values ​​corresponding to the respective time sequences, and obtain the parameters of the dynamic resistance of the measured gallium nitride power tube.

6. The method according to claim 5, characterized in that Step C also includes: Whether the tested GaN power tube is normal is determined according to whether the characteristic curve corresponding to the parameter of the dynamic resistance conforms to the characteristic curve corresponding to the normal GaN power tube.

7. The method according to claim 5, characterized in that The synchronous control signal for setting the timing includes: Control the high-speed driving circuit to drive the tested gallium nitride power tube to conduct and control the low-voltage output circuit to provide a low voltage between the drain and the source of the gallium nitride power tube, the duration is T1; The high-speed driving circuit is controlled to drive the tested gallium nitride power tube to be disconnected and the high-voltage output circuit is controlled to provide high voltage between the drain and the source of the gallium nitride power tube, the duration is T2, and T2>T1.

Images