A gate charge test circuit

Abstract

The embodiment of the present application provides a gate charge test circuit, and relates to the field of power semiconductor device testing. The gate charge test circuit comprises a constant current source unit, a gate current control unit, a signal generation unit, a drain current loading control unit, an adjustable electronic load unit, a to-be-tested field effect power device and a charge test unit. The constant current source unit provides a constant current for the gate of the to-be-tested field effect power device, the gate current control unit and the signal generation unit control the time of the current acting on the gate of the to-be-tested field effect power device, the drain current loading control unit and the adjustable electronic load unit control the current flowing through the drain of the to-be-tested field effect power device, and finally the charge test unit measures the gate charge of the to-be-tested field effect power device. The gate charge of the to-be-tested field effect power device can be tested through the above circuit.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of power semiconductor device testing, in particular to a gate charge test circuit. BACKGROUND

[0002] Field effect power devices are widely used in various electronic devices due to their fast switching speed, high reliability, strong overload capacity and small driving power. Gate charge is the total amount of charge required to start a field effect power device, and is an important indicator of the performance of a field effect power device. How to measure the gate charge is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0003] In order to overcome the technical problems mentioned in the above technical background, the embodiments of the present application provide a gate charge test circuit.

[0004] In a first aspect of the present application, a gate charge test circuit is provided, which comprises a constant current source unit, a gate current control unit, a signal generation unit, a drain current loading control unit, an adjustable electronic load unit, a field effect power device to be tested and a charge test unit.

[0005] The constant current source unit is connected to the gate of the field effect power device to be tested, and is used to provide a constant current for the gate of the field effect power device to be tested.

[0006] The input end of the gate current control unit is connected to the signal generation unit, and the output end of the gate current control unit is connected between the output end of the constant current source unit and the gate of the field effect power device to be tested. The gate current control unit is used to control the time length of the constant current source unit providing a constant current for the gate of the field effect power device to be tested according to the signal input by the signal generation unit.

[0007] The drain current loading control unit is connected to the drain of the field effect power device to be tested through the adjustable electronic load unit, and is used to provide a drain current for the field effect power device to be tested.

[0008] The charge test unit is used to test the gate charge of the field effect power device to be tested.

[0009] In a possible embodiment of the present application, the constant current source unit comprises a first resistor, a second resistor, a third resistor, an operational amplifier and a first triode,

[0010] One end of the first resistor and one end of the second resistor are connected, the other end of the first resistor is connected to a first voltage signal, and the other end of the second resistor is connected to a first ground signal.

[0011] One end of the third resistor is connected to the first voltage signal, and the other end of the third resistor is connected to the input terminal of the first transistor;

[0012] The inverting input terminal of the operational amplifier is connected between the third resistor and the first transistor, the non-inverting input terminal of the operational amplifier is connected between the first resistor and the second resistor, the output terminal of the operational amplifier is connected to the control terminal of the first transistor, and the output terminal of the first transistor outputs a constant current.

[0013] In a possible embodiment of the present application, the gate current control unit comprises a fourth resistor, a fifth resistor, a first fuse, a transient diode, a second transistor, and a connector;

[0014] One end of the first fuse is connected to the first output pin of the connector, and the other end of the first fuse is connected to the control terminal of the second transistor through the fourth resistor;

[0015] The fifth resistor is connected between the control terminal of the second transistor and the output terminal of the second transistor, wherein the output terminal of the second transistor is connected to a second ground signal;

[0016] The second output pin of the connector is connected to the output terminal of the second transistor, one end of the transient diode is connected between the first fuse and the first output pin of the connector, and the other end of the transient diode is connected to the output terminal of the second transistor;

[0017] The input terminal of the second transistor is connected to the output terminal of the first transistor.

[0018] In a possible embodiment of the present application, the gate current control unit is connected to the signal generation unit through the connector;

[0019] The signal generation unit adjusts the on-off state of the second transistor in the gate current control unit through the generated pulse signal.

[0020] In a possible embodiment of the present application, the constant current source unit further comprises a parallel branch formed by a first diode, a second diode, and a first capacitor, wherein the anode of the first diode and the cathode of the second diode are connected, the cathode of the first diode and the anode of the second diode are connected, and the first capacitor is connected in parallel with the first diode and the second diode respectively;

[0021] One end of the parallel branch is connected to the first ground signal, and the other end of the parallel branch is connected to the second ground signal.

[0022] In a possible embodiment of the present application, the first triode is a PNP bipolar junction triode, the control end of the first triode is a base, the input end of the first triode is an emitter, and the output end of the first triode is a collector.

[0023] The second triode is an NPN bipolar junction triode, the control end of the first triode is a base, the input end of the first triode is a collector, and the output end of the first triode is an emitter.

[0024] In a possible embodiment of the present application, the drain current loading control unit comprises a second fuse and a variable resistor.

[0025] One end of the second fuse is connected to a third voltage signal, the other end of the second fuse is connected to the input end of the adjustable electronic load unit, the control end of the adjustable electronic load unit is connected to the sliding end of the variable resistor, and the output end of the adjustable electronic load unit is connected to the drain of the field effect power device to be tested, wherein the first fixed end of the variable resistor is connected to a second voltage signal, and the second fixed end of the variable resistor is connected to the third ground signal.

[0026] The gate of the field effect power device to be tested is connected to the output end of the first triode.

[0027] In a possible embodiment of the present application, the drain current loading control unit further comprises a second capacitor.

[0028] One electrode of the second capacitor is connected between the second fuse and the input end of the adjustable electronic load unit, and the other electrode of the second capacitor is connected to the source of the field effect power device to be tested, wherein the source of the field effect power device to be tested is connected to a ground signal.

[0029] In a possible embodiment of the present application, the adjustable electronic load unit comprises a bipolar junction triode, a metal-oxide-semiconductor field effect transistor, and an insulated gate bipolar transistor.

[0030] In a possible embodiment of the present application, the charge test unit comprises a voltage test probe and a current test probe.

[0031] The two voltage test probes are respectively connected to the gate and the source of the field effect power device to be tested, for testing the voltage between the gate and the source of the field effect power device to be tested.

[0032] The current test probe is arranged between the drain of the field effect power device to be tested and the output end of the adjustable electronic load unit, for testing the drain current flowing through the field effect power device to be tested.

[0033] The gate charge test circuit provided by the embodiment of the present application comprises a constant current source unit, a gate current control unit, a signal generation unit, a drain current loading control unit, an adjustable electronic load unit, a field effect power device to be tested and a charge test unit. The constant current source unit provides a constant current for the gate of the field effect power device to be tested, the gate current control unit and the signal generation unit control the time of the current acting on the gate of the field effect power device to be tested, the drain current loading control unit and the adjustable electronic load unit control the current flowing through the drain of the field effect power device to be tested, and finally the charge test unit measures the gate charge of the field effect power device to be tested. The gate charge of the field effect power device to be tested can be tested through the above circuit. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0035] Figure 1 Vgs-t curve schematic diagram of the field effect power device;

[0036] Figure 2 Block schematic diagram of the gate charge test circuit provided by the embodiment of the present application.

[0037] Figure 3 Specific structure schematic diagram of the gate charge test circuit provided by the embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0040] It should be noted that like reference numerals and characters refer to like elements throughout the following figures and description, and thus, once certain terminologies are defined in one figure, they do not need to be further defined and explained in the subsequent figures.

[0041] In the description of the present application, unless specifically defined and limited otherwise, the terms "set", "connected", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected; can be mechanical connection, can also be connection; can be directly connected, can also be indirectly connected through intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] The working principle of the gate charge test can be that the gate of the field effect power device always inputs a constant current, and the Vgs-t curve can be obtained by testing the change of the gate-source voltage Vgs with time. Since the gate current is constant, the gate charge Qg can be represented by the product of the gate current and the time of the input gate current. Please refer to Figure 1 The gate charge can be composed of three different inclined segments, wherein Qg is the gate charge, Qgs is the gate-source charge, and Qgd is the gate-drain charge. Figure 1 As can be seen from the curve, Qgs is the charge from the starting 0 point to the first inflection point, Qgd is the charge from the first inflection point to the second inflection point, and Qg is the charge from the starting 0 point to the VGS drive peak voltage.

[0043] In order to solve the technical problems in the background art, the embodiment of the present application provides a gate charge test circuit. Please refer to Figure 2 The gate charge test circuit 10 can include a constant current source unit 110, a gate current control unit 120, a signal generating unit 130, a drain current loading control unit 140, an adjustable electronic load unit 150, a field effect power device to be tested 160, and a charge test unit 170.

[0044] In the embodiment, the constant current source unit 110 is connected with the gate of the field effect power device to be tested 160, for providing constant current for the gate of the field effect power device to be tested 160. The input end of the gate current control unit 120 is connected with the signal generating unit 130, and the output end of the gate current control unit 120 is connected between the output end of the constant current source unit 110 and the gate of the field effect power device to be tested 160, for controlling the time length of the constant current source unit 110 providing constant current for the gate of the field effect power device to be tested 160 according to the signal input by the signal generating unit 130.

[0045] The drain current loading control unit 140 is connected with the drain of the field effect power device 160 to be tested through the adjustable electronic load unit 150, and is used to provide the drain current for the field effect power device 160 to be tested.

[0046] The charge test unit 170 is used to test the gate charge of the field effect power device 160 to be tested.

[0047] The above-mentioned circuit provides a constant current for the gate of the field effect power device 160 to be tested through the constant current source unit 110, controls the time of the current acting on the gate of the field effect power device 160 to be tested through the gate current control unit 120 and the signal generation unit 130, controls the current flowing through the drain of the field effect power device 160 to be tested through the drain current loading control unit 140 and the adjustable electronic load unit 150, and finally measures the gate charge of the field effect power device 160 to be tested through the charge test unit 170. The gate charge of the field effect power device 160 to be tested can be tested through the above-mentioned circuit.

[0048] The inventor further found that the existing gate charge test circuit has the problem of low test accuracy. The inventor found through research that the main reason for this problem is that the constant direct current provided for the gate of the field effect power device 160 to be tested is not stable, thereby causing the problem of low accuracy of the final gate charge test. In order to solve the above-mentioned problem, the constant current source unit 110 provided in the embodiment can be realized through the following circuit.

[0049] Please refer to Figure 3 The constant current source unit 110 includes a first resistor R1, a second resistor R2, a third resistor R3, an operational amplifier IC1A and a first triode Q1. One end of the first resistor R1 and one end of the second resistor R2 are connected, the other end of the first resistor R1 is connected with a first voltage signal VCC1, and the other end of the second resistor R2 is connected with a first ground signal GND1. One end of the third resistor R3 is connected with the first voltage signal VCC1, and the other end of the third resistor R3 is connected with the input end of the first triode Q1. The inverting input end (pin 2 in the figure) of the operational amplifier IC1A is connected between the third resistor R3 and the first triode Q1, the non-inverting input end (pin 3 in the figure) of the operational amplifier IC1A is connected between the first resistor R1 and the second resistor R2, the output end of the operational amplifier IC1A is connected with the control end of the first triode Q1, the positive electrode (pin 8 in the figure) of the operational amplifier IC1A is connected with the first voltage signal VCC1, the negative electrode (pin 4 in the figure) of the operational amplifier IC1A is connected with the first ground signal GND1, and the output end of the first triode Q1 outputs a constant current.

[0050] In the above circuit, the first resistor R1 and the second resistor R2 are connected in series to form a voltage divider circuit, the voltage on the second resistor R2 is used as a reference voltage to the non-inverting input terminal of the operational amplifier IC1A, the third resistor R3 is used as a current sampling resistor, the inverting input terminal of the operational amplifier IC1A is connected between the third resistor R3 and the first transistor Q1, and the connection forms a negative feedback amplifier circuit. If the current flowing through the third resistor R3 changes (for example, increases), the voltage at the inverting input terminal of the operational amplifier IC1A changes, and the amplified output signal will adjust (for example, decrease) the current in the branch where the third resistor R3 and the first transistor Q1 are located, so that the current flowing through the branch where the third resistor R3 and the first transistor Q1 are located is constant, and the output terminal of the first transistor Q1 outputs a constant current, wherein the first transistor Q1 operates in an amplification state. In this way, it can be ensured that the current provided to the gate of the field effect power device 160 to be tested is a constant direct current, thereby improving the accuracy of the gate charge test.

[0051] Further, referring again to Figure 3 , the gate current control unit 120 can include a fourth resistor R4, a fifth resistor R5, a first fuse F1, a transient voltage suppressor (TVS) diode, a second transistor Q2, and a connector J1. One end of the first fuse F1 is connected to a first output pin of the connector J1, and the other end of the first fuse F1 is connected to the control terminal of the second transistor Q2 through the fourth resistor R4. The fifth resistor R5 is connected between the control terminal of the second transistor Q2 and the output terminal of the second transistor Q2, wherein the output terminal of the second transistor Q2 is connected to a second ground signal GND2. A second output pin of the connector J1 is connected to the output terminal of the second transistor Q2, one end of the transient voltage suppressor (TVS) diode is connected between the first fuse F1 and the first output pin of the connector J1, and the other end of the transient voltage suppressor (TVS) diode is connected to the output terminal of the second transistor Q2. The input terminal of the second transistor Q2 is connected to the output terminal of the first transistor Q1.

[0052] In this embodiment, the gate current control unit 120 is connected to the signal generation unit 130 through the connector J1, and the signal generation unit 130 adjusts the on-off state of the second transistor Q2 in the gate current control unit 120 by generating a pulse signal. For example, when the signal generation unit 130 sends a high-level signal, the second transistor Q2 can be controlled to be turned on, and when the second transistor Q2 is turned on, the output terminal of the first transistor Q1 is grounded through the second transistor Q2, at this time, the constant current source unit 110 does not provide a constant current to the gate of the field effect power device 160 to be tested. When the signal generation unit 130 sends a low-level signal, the second transistor Q2 can be controlled to be turned off, and at this time, the constant current source unit 110 provides a constant current to the gate of the field effect power device 160 to be tested.

[0053] In the above structure of the gate current control unit 120, when the input voltage of the second transistor Q2 increases due to the increase of the back-end voltage, the signal generating unit 130 connected with the connector J1 can be protected by the transient voltage suppression (TVS) diode and the protection can be realized by fusing the first fuse F1.

[0054] Further, in the present embodiment, please refer to Figure 3 The constant current source unit 110 can further include a parallel branch formed by the first diode D1, the second diode D2 and the first capacitor C1, in which the anode of the first diode D1 and the cathode of the second diode D2 are connected, the cathode of the first diode D1 and the anode of the second diode D2 are connected, and the first capacitor C1 is connected in parallel with the first diode D1 and the second diode D2 respectively. One end of the parallel branch is connected with the first ground signal GND1, and the other end of the parallel branch is connected with the second ground signal GND2. The above design can form a certain voltage difference (for example, 0.7V) between the first ground signal GND1 and the second ground signal GND2, and the inventor finds that the above design can make the turn-off speed of the second transistor Q2 faster, and the time length of providing the constant current to the gate of the field effect power device 160 by the constant current source unit 110 more accurate. Meanwhile, the first capacitor C1 can filter the interference signals caused by signal fluctuation.

[0055] In the present embodiment, the first transistor Q1 is a PNP bipolar junction transistor, the control end of the first transistor Q1 is the base, the input end of the first transistor Q1 is the emitter, and the output end of the first transistor Q1 is the collector. The second transistor Q2 is an NPN bipolar junction transistor, the control end of the first transistor Q3 is the base, the input end of the second transistor Q2 is the collector, and the output end of the second transistor Q2 is the emitter.

[0056] Further, please refer to Figure 3In this embodiment, the drain current loading control unit 140 includes a second fuse F2 and a variable resistor W1. One end of the second fuse F2 is connected to a third voltage signal VCC3, and the other end is connected to the input terminal of an adjustable electronic load unit 150. The control terminal of the adjustable electronic load unit 150 is connected to the sliding terminal of the variable resistor W1, and the output terminal of the adjustable electronic load unit 150 is connected to the drain of the field-effect power device 160 under test. The first fixed terminal of the variable resistor W1 is connected to a second voltage signal VCC2, and the second fixed terminal of the variable resistor W1 is connected to a third ground signal GND3. The gate of the field-effect power device 160 under test is connected to the output terminal of a first transistor Q1. By adjusting the variable resistor W1, the drain current of the field-effect power device 160 under test can be changed to adjust the test drain current of the field-effect power device 160. The second fuse F2 can provide fuse protection for the field-effect power device 160 under test when the drain current is too large.

[0057] In this embodiment, the drain current loading control unit 140 further includes a second capacitor C2. One electrode of the second capacitor C2 is connected between the second fuse F2 and the input terminal of the adjustable electronic load unit 150, and the other electrode of the second capacitor C2 is connected to the source of the field-effect power device 160 under test, wherein the source of the field-effect power device 160 under test is connected to the first ground signal GND1. This design can filter interference signals.

[0058] In this embodiment, the adjustable electronic load unit 150 may include a bipolar junction transistor, a metal-oxide-semiconductor field-effect transistor, and an insulated gate bipolar transistor.

[0059] Further, in this embodiment, the charge testing unit 170 includes a voltage testing probe and a current testing probe. The two voltage testing probes are respectively connected to the gate and source of the field-effect power device 160 under test, and are used to test the voltage between the gate and source of the field-effect power device 160 under test. The current testing probe is disposed between the drain of the field-effect power device 160 under test and the output terminal of the adjustable electronic load unit 150. Figure 3 The charge test unit 170 (located at the ID position) is used to test the current flowing through the drain of the field-effect power device 160 under test. The charge test unit 170 can be an oscilloscope, which can measure the time waveform of the gate charge of the field-effect power device 160 under test.

[0060] In summary, the embodiment of the present application provides a gate charge test circuit, which comprises a constant current source unit, a gate current control unit, a signal generation unit, a drain current loading control unit, an adjustable electronic load unit, a to-be-tested field effect power device and a charge test unit. The constant current source unit provides a constant current for the gate of the to-be-tested field effect power device, the gate current control unit and the signal generation unit control the time of the current acting on the gate of the to-be-tested field effect power device, the drain current loading control unit and the adjustable electronic load unit control the current flowing through the drain of the to-be-tested field effect power device, and finally the charge test unit measures the gate charge of the to-be-tested field effect power device. The gate charge of the to-be-tested field effect power device can be tested through the above circuit.

[0061] The above merely provides preferred embodiments of the present application but is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A gate charge test circuit, characterized by, The gate charge test circuit comprises a constant current source unit, a gate current control unit, a signal generation unit, a drain current loading control unit, an adjustable electronic load unit, a field effect power device to be tested and a charge test unit; The constant current source unit is connected with the gate of the field effect power device to be tested, and is configured to provide constant current for the gate of the field effect power device to be tested; An input end of the gate current control unit is connected with the signal generation unit, and an output end of the gate current control unit is connected between an output end of the constant current source unit and the gate of the field effect power device to be tested, and is configured to control the constant current source unit to provide constant current for the gate of the field effect power device to be tested for a time length according to a signal input by the signal generation unit; The drain current loading control unit is connected with a drain of the field effect power device to be tested through the adjustable electronic load unit, and is configured to provide drain current for the field effect power device to be tested; The charge test unit is configured to test the gate charge of the field effect power device to be tested; The constant current source unit comprises a first resistor, a second resistor, a third resistor, an operational amplifier and a first triode, one end of the first resistor and one end of the second resistor are connected, the other end of the first resistor is connected with a first voltage signal, and the other end of the second resistor is connected with a first ground signal; One end of the third resistor is connected with the first voltage signal, and the other end of the third resistor is connected with an input end of the first triode; An inverting input end of the operational amplifier is connected between the third resistor and the first triode, a non-inverting input end of the operational amplifier is connected between the first resistor and the second resistor, an output end of the operational amplifier is connected with a control end of the first triode, and an output end of the first triode outputs constant current; The gate current control unit comprises a fourth resistor, a fifth resistor, a first fuse, a transient diode, a second triode and a connector; One end of the first fuse is connected with a first output pin of the connector, and the other end of the first fuse is connected with a control end of the second triode through the fourth resistor; The fifth resistor is connected between the control end of the second triode and an output end of the second triode, wherein the output end of the second triode is connected with a second ground signal; The first output pin of the connector is connected with the output end of the second triode, one end of the transient diode is connected between the first fuse and the first output pin of the connector, and the other end of the transient diode is connected with the output end of the second triode; An input end of the second triode is connected with the output end of the first triode; The gate current control unit is connected with the signal generation unit through the connector; The signal generation unit adjusts the on-off state of the second triode in the gate current control unit by a generated pulse signal.

2. The gate charge test circuit of claim 1, wherein, The constant current source unit further comprises a parallel branch formed by a first diode, a second diode and a first capacitor, in which the anode of the first diode and the cathode of the second diode are connected, the cathode of the first diode is connected with the anode of the second diode, and the first capacitor is connected in parallel with the first diode and the second diode respectively; One end of the parallel branch is connected with the first ground signal, and the other end of the parallel branch is connected with the second ground signal.

3. The gate charge test circuit of any of claims 1-2, wherein, The first triode is a PNP bipolar junction triode, the control end of the first triode is a base, the input end of the first triode is an emitter, and the output end of the first triode is a collector; The second triode is an NPN bipolar junction triode, the control end of the second triode is a base, the input end of the second triode is a collector, and the output end of the second triode is an emitter.

4. The gate charge test circuit of any of claims 1-2, wherein, The drain current loading control unit comprises a second fuse and a variable resistor; One end of the second fuse is connected with a third voltage signal, the other end of the second fuse is connected with the input end of the adjustable electronic load unit, the control end of the adjustable electronic load unit is connected with the sliding end of the variable resistor, and the output end of the adjustable electronic load unit is connected with the drain of the field effect power device to be tested, wherein the first fixed end of the variable resistor is connected with a second voltage signal, and the second fixed end of the variable resistor is connected with a third ground signal; The gate of the field effect power device to be tested is connected with the output end of the first triode.

5. The gate charge test circuit of claim 4, wherein, The drain current loading control unit further comprises a second capacitor; One electrode of the second capacitor is connected between the second fuse and the input end of the adjustable electronic load unit, and the other electrode of the second capacitor is connected with the source of the field effect power device to be tested, wherein the source of the field effect power device to be tested is connected with a ground signal.

6. The gate charge test circuit of claim 5, wherein, The adjustable electronic load unit comprises a bipolar junction triode, a metal-oxide-semiconductor field effect transistor and an insulated gate bipolar transistor.

7. The gate charge test circuit of claim 5, wherein, The charge test unit comprises a voltage test probe and a current test probe; The two voltage test probes are respectively connected with the gate and the source of the field effect power device to be tested, for testing the voltage between the gate and the source of the field effect power device to be tested; The current test probe is arranged between the drain of the field effect power device to be tested and the output end of the adjustable electronic load unit, for testing the current flowing through the drain of the field effect power device to be tested.

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