JP2010175509A - Device for measuring reverse-bias area of safe operation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably measure a reverse-bias area of the safe operation of an element to be measured without damaging the element to be measured or a component of a measuring circuit. <P>SOLUTION: A diode (8) is connected in the reverse direction between the collector and emitter of an element to be measured (1). This diode (8) withstands higher pressure than does the element to be measured. The collector voltage of this element to be measured is clamped by a clamping circuit (10). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus for measuring electrical characteristics of a transistor element, and more particularly to an apparatus for measuring an IGBT (Insulated Gate Bipolar Transistor) and a reverse bias safe operating region of a bipolar transistor.

  As power switching elements that perform power conversion and control, there are semiconductor switching elements (power transistors) such as IGBTs, bipolar transistors, and power MOSFETs (insulated gate field effect transistors). Since these power transistors handle large power and large current, it is necessary to sufficiently increase the breakdown resistance. In order to ensure the reliability of such an element, generally, for a power transistor or the like, a test is performed to determine whether the element satisfies a desired specification value (rated value) after the manufacturing process is completed.

  One of the performance evaluation items measured at the time of testing the power transistor is a reverse bias safe operation area (RBSOA) of the bipolar transistor and the IGBT. RBSOA is a region defined by the maximum values of the collector-emitter voltage VCE and the collector-emitter current ICE that the IGBT (or bipolar transistor) does not break down when the IGBT (or bipolar transistor) is turned off. An example of a configuration for measuring RBSOA using a bipolar transistor as a measurement target is shown in Patent Document 1 (Japanese Patent Laid-Open No. 62-38372).

  In the configuration disclosed in Patent Document 1, a clamp circuit is used to clamp the collector voltage when the bipolar transistor is turned off. An inductive load (coil) is used as the driving load, and this inductive load is connected to the main power source. The main power supply has a positive electrode connected to the collector of the bipolar transistor to be measured via an inductive load, and a negative electrode connected to the emitter of the bipolar transistor.

  The clamp circuit includes a clamp power supply, a clamp diode, a resistance element, and a capacitance element. The clamp diode has an anode connected to the collector of the bipolar transistor to be measured and a cathode connected to a clamp power source. The resistor element and the capacitor element are connected in parallel between the cathode of the clamp diode and the emitter of the bipolar transistor, and the clamp power supply is connected in parallel with these capacitor element and resistor element.

  At the time of measurement, the collector current is increased by increasing the collector voltage (main power supply voltage) of the bipolar transistor to be measured or increasing the current supply width of the base current. The trajectory of the collector-emitter voltage and collector current is measured, and the safe operation area is evaluated.

  A configuration for conducting a reverse recovery test of a diode connected in the reverse direction between the collector and emitter of a bipolar transistor is shown in Patent Document 2 (Japanese Patent Laid-Open No. 2001-228201). In this Patent Document 2, a single IGBT and a diode are connected in antiparallel, and the IGBT is set in a reverse bias state by applying -15 V to its gate (control electrode). A second IGBT chip is connected in series with the IGBT, and the second IGBT is turned on, turned off, and turned on. When the second IGBT is turned on for the second time, the diode chip shifts from the on state to the off state, and a reverse recovery test is performed on the diode chip. In the reverse recovery test of this diode chip, the IGBT to be measured that is destroyed by switching loss (product of collector-emitter voltage and collector current) is identified. The destroyed IGBT chip is removed, and the remaining non-destructed IGBT chip is selected to constitute an IGBT module.

JP-A-62-38372 JP 2001-228201 A

  When an inductive load such as a coil is driven by an IGBT or a bipolar transistor, a surge is generated by the inductive load at the time of turn-off, and the surge voltage is superimposed on the collector voltage. The clamp circuit disclosed in Patent Document 1 described above absorbs this surge voltage and clamps the collector voltage to a predetermined voltage level. In this clamp circuit, a surge voltage is discharged to the capacitive element via the diode element. When the clamp diode absorbs the surge voltage and shifts from the on state to the off state, the recovery current flows to the inductive load in the reverse direction. Even if the recovery current does not flow due to complete emission of minority carriers of the diode element, the current flowing through the inductive load tends to continue to flow even after the recovery current is cut off. Therefore, a current flows again in the reverse direction from the IGBT of the device under test or the emitter of the bipolar transistor to the collector.

  In this case, the current flows through the IGBT or bipolar transistor of the element to be measured in a direction opposite to the direction in which the current originally flows, so that the voltage drop between the emitter and the collector due to the reverse current becomes very large. Since the IGBT of the device under test or the emitter of the bipolar transistor is connected to the ground node, the collector voltage becomes a negative voltage, that is, a negative surge voltage is superimposed on the collector voltage. Due to this negative surge voltage, the clamp diode is damaged or the measuring instrument malfunctions.

  This negative surge voltage tends to increase as the recovery current of the clamp diode increases (since the inductive load causes a current against the recovery current to flow). In order to reduce this negative surge voltage, it is necessary to use a diode with a small recovery current as a clamp diode. In order to reduce the recovery current, it is necessary to use a diode having a small chip size. However, when the chip size is reduced, there is a possibility that the clamp diode may be destroyed by a forward current that is driven during the clamp operation. The clamp diode needs to have a high reverse breakdown voltage so that it can withstand a reverse bias voltage when a negative surge voltage is generated. However, when the withstand voltage of this diode is increased, the recovery current tends to increase, and both are in a trade-off relationship, and are difficult to solve at the same time. Further, when this negative surge voltage occurs, a voltage having a reverse polarity is applied to a measuring instrument that measures the collector-emitter voltage of the device under measurement, which may cause a malfunction.

  In the above-mentioned Patent Document 1, in order to measure this safe operation region, the voltage / current point at which the transistor under measurement is actually broken is measured. No consideration has been given to the problem of negative surge voltage generation due to inductive loads.

  Patent Document 2 discloses that a reverse leakage current flows through the IGBT during a reverse recovery test of a diode connected in the reverse direction between the collector and emitter of the IGBT. The normal / defective determination is performed by identifying the normal chip according to whether the identification IGBT is broken at the turn-off or the reverse leakage current below the specified value flows, and only the normal chip is used. However, even in this Patent Document 2, no consideration is given to the recovery current of the reverse diode (freewheel diode) and the generation of a negative surge voltage due to an inductive load. In the configuration shown in Patent Document 2, when a negative voltage surge occurs and the transistor is destroyed, it is impossible to identify whether or not the transistor is destroyed due to a condition outside the safe operation region. An accurate test cannot be performed.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an apparatus that can safely measure a reverse bias safe operating region without causing destruction of a device under test.

  The reverse bias safe operation region measuring apparatus according to the first aspect of the present invention has a breakdown voltage higher than the breakdown voltage level of the transistor element connected in reverse parallel between the first and second main electrodes of the transistor element to be measured. And a clamp circuit for clamping the first main electrode voltage of the transistor element.

  A reverse bias safe operation region measuring apparatus according to a second aspect of the present invention includes a clamp power source, a capacitor charged at least by a voltage generated by the clamp power source, a first main electrode of the transistor element, and the clamp power source. And a backflow prevention diode connected in the same direction as the clamp diode between the clamp diode and the capacitor.

  By connecting the diode element in the reverse direction between the first and second main electrodes of the transistor element, the reverse current flowing through the transistor element can be bypassed when the diode element is turned off, and negative surge voltage generation is suppressed. can do.

  In addition, by connecting a backflow prevention diode in the forward direction when viewed from the clamp diode between the clamp diode and the clamp capacitor, the path of the current flowing from the capacitor serving as the recovery current source of the clamp diode can be cut off. Therefore, the recovery current of the clamp diode can be cut off, and accordingly, the reverse leakage current can be prevented from flowing through the transistor element to be measured.

It is a figure which shows the structure of the reverse bias safe operation area | region measuring apparatus according to Embodiment 1 of this invention. It is a figure which shows only the collector current-collector-emitter voltage at the time of reverse bias safe operation area | region measurement. It is a figure which shows the path | route through which the electric current flows at the time of turn-on of the to-be-measured element in the measuring apparatus according to Embodiment 1 of this invention. It is a figure which shows the path | route through which the electric current flows at the time of turn-off transition of the to-be-measured element in the measuring apparatus according to Embodiment 1 of this invention. It is a figure which shows the path | route through which the electric current after a to-be-measured element interruption | blocking flows. It is a figure which shows the path | route through which the electric current at the time of the recovery operation | movement of a clamp diode flows. It is a figure which shows the path | route through which the reverse direction current after this recovery operation | movement flows. It is a figure which shows the electric current and voltage waveform of a measurement circuit when the backflow prevention diode with respect to a to-be-measured element is not connected. It is a figure which shows the electric current and voltage waveform in the measurement circuit shown in FIG. It is a figure which shows the structure of the reverse bias safe operation area | region measuring apparatus according to Embodiment 2 of this invention. It is a figure which shows the structure of the measuring apparatus according to Embodiment 3 of this invention. It is a figure which shows the structure of the measuring apparatus according to Embodiment 4 of this invention. It is a figure which shows the structure of the measuring apparatus according to Embodiment 5 of this invention. It is a figure which shows the structure of the measuring apparatus according to Embodiment 6 of this invention.

[Embodiment 1]
1 is a diagram showing a configuration of a reverse bias safe operation region measuring apparatus according to a first embodiment of the present invention. In FIG. 1, a reverse bias safe operation region measurement circuit 2 is connected to a device under test 1. For example, the device under test 1 is an IGBT 4 in a bare chip state. The device under test 1 may be a bipolar transistor instead of an IGBT, and may be any device that can measure the reverse bias safe operation region in a bare chip state. In the following description, the IGBT 4 is shown as the element to be measured 1. However, since it may be a bipolar transistor, it is simply referred to as the element to be measured 1.

  The reverse bias safe operation region is measured by the measurement circuit 2 when the device under test 1 is in a bare chip state. The measurement circuit 2 includes a main power supply 13, an inductive load (L load) 12 connected between the main power supply 13 and the collector terminal of the device under test 1, and a capacitor 14 connected in parallel with the main power supply 13. Including. The main power supply 13 has a positive electrode connected to the inductive load 12. Capacitor 14 is formed of, for example, an electrolytic capacitor, has a large capacitance value, and stabilizes the power supply voltage (VCC) of main power supply 13.

  Inductive load 12 is formed of a coil, for example. By using this inductive load 12, a surge voltage is generated when the device under test 1 is turned off. Power transistors such as IGBTs and bipolar transistors are often used for driving inductive loads such as motors during actual use, and are adapted to the situation during actual use.

  The measurement circuit 2 further includes a clamp circuit 10 that clamps the collector voltage of the device under test 1 and a diode device 8 connected in antiparallel between the collector and emitter outside the device under test 1. The diode element 8 has an anode connected to the collector of the element 1 to be measured and a cathode connected to the emitter of the element 1 to be measured. The clamp circuit 10 includes a clamp power source 16, a clamp diode 15 connected in a forward direction between the collector of the device 1 to be measured 1 and the clamp power source 16, and the clamp power source 16 in parallel between the clamp diode 15 and the ground node. And a capacitor 17 to be connected. This capacitor 17 is used to stabilize the voltage of the clamp power supply 16. The clamp die auto 15 has an anode connected to the collector of the element 1 to be measured and a cathode connected to the positive electrode of the clamp power supply 16.

  Since the diode element 8 is set in a reverse bias state when the device under test 1 is turned off, the diode device 8 has a withstand voltage greater than that of the device under test 1. The diode element 8 is composed of a chip different from the element 1 to be measured. At the time of this measurement, the diode element 8 is semi-fixedly connected between the collector and emitter of the element 1 to be measured in reverse parallel using a probe or the like. It is separated from the device under test 1 during actual use or after completion of measurement.

  The clamp circuit 10 clamps the upper limit of the collector voltage of the device under test 1 to the voltage level of the sum of the voltage of the clamp power supply 16 and the forward drop voltage of the clamp diode 15. The voltage generated by the clamp power supply 16 is set to a voltage level higher than the voltage generated by the main power supply 13, and current is prevented from flowing from the main power supply to the clamp circuit 10 at all times.

  The measurement circuit 2 is included in the measurement apparatus main body. The measurement apparatus includes a current sensor CT, and a current flowing through the collector of the device under test 1 is detected, and a collector-emitter current ICE is measured. In addition, a voltmeter is arranged in a measurement apparatus main body (not shown), and a collector-emitter voltage of the device under test 1 is measured using a probe (not shown).

  At the time of normal reverse bias safe operation region measurement, a pulsed drive signal is given from a gate driver included in a measurement apparatus main body (not shown), the device under test 1 is driven to an ON state, and the main device is connected via an inductive load 12. A current is passed from the power supply 13 to the element to be measured. The current flowing between the collector and emitter of the device under test 1 is proportional to the pulse width of the drive signal applied to the control electrode (gate) of the device under test 1 from the gate driver. When the pulse width of the drive signal is adjusted and the current flowing through the device under test 1 reaches a current of a predetermined magnitude (for example, a rated current value), the drive signal of the device under test 1 is changed to a reverse bias state, for example. The device under test 1 is set to the off state and the device under test 1 is driven to the off state. When the device under test 1 transitions from an on state to an off state, the current flowing through the main electrode (collector and emitter electrode) does not instantaneously drop to 0 A (ampere) but reaches 0 A while being attenuated. To do. At this time, the collector voltage is fixed at the clamp voltage by the clamp circuit 10, and while the current flows through the inductive load 12, the collector voltage of the device under test 1 is clamped to the clamp voltage of the clamp circuit 10. Therefore, when the device under test 1 is turned off during normal reverse bias safe operation region measurement, an IV waveform (Lissajous waveform) as shown in FIG. 2 is obtained.

  In FIG. 2, the vertical axis represents the collector current ICE, and the horizontal axis represents the collector-emitter voltage VCE. From this Lissajous waveform, is a region RG defined by the maximum value (for example, rated value) of the collector current ICE and the maximum value (for example, rated voltage) of the collector-emitter voltage VCE present in the reverse bias safe operation region RBSOA? Can be identified. Next, the absorption of the negative voltage surge in the measurement circuit according to the first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 3, when the device under test 1 is in the ON state, a current I flows between the collector and emitter of the device under test 1 via the inductive load 12.

  Next, when the device under test 1 shifts from the on state to the off state, the current flowing between the main electrodes (between the collector and the emitter) of the device under test 1 begins to attenuate as shown in FIG. Due to the energy stored in 12, currents of the same magnitude continue to flow. Therefore, the current I that flows through the inductive load 12 is shunted to the clamp circuit 10 by the amount that the current I1 that flows through the device under test 1 falls below the current I. That is, the clamp diode 15 is turned on, and the capacitor 17 is charged by the current I2.

  Next, as shown in FIG. 5, when the device under test 1 is completely turned off and the current path between its main electrodes is interrupted, all the current I flowing through the inductive load 12 flows through the clamp circuit 10, The capacitor 17 is charged via the clamp diode 15.

  Since the clamp voltage of the clamp circuit 10 is higher than the voltage VCC of the main power supply 13, the current flowing through the inductive load 12 attenuates at a constant rate and once becomes 0A. Thereafter, as shown in FIG. 6, due to the recovery characteristic of the clamp diode 15, the recovery current flows from the positive electrode of the clamp power supply 16 and flows to the positive electrode of the main power supply 13 through the inductive load 12. At this time, when the minority carriers of the clamp diode 15 are completely eliminated, the current flowing between the cathode and the anode of the clamp diode 15 is cut off.

  However, the current flowing through the inductive load 12 tends to continue to flow even after the clamp diode 15 is cut off due to the self-induction. At this time, as shown in FIG. 7, the diode element 8 is forward-biased by the current flowing through the inductive load 12 and is turned on, and the current flowing through the inductive load 12 passes through the diode element 8 from the ground node. The current flows to the main power source 13 and no current flows between the emitter and collector of the device under test 1. At this time, the diode element 8 is connected in the forward direction and is in the on state, and the forward voltage drop is sufficiently smaller than the voltage drop amount in the reverse bias state between the emitter and the collector of the element 1 to be measured and is negative. Generation of surge voltage can be suppressed, and damage to the clamp diode 15 and malfunction in a measuring instrument (not shown) coupled to the current sensor CT can be prevented. Further, in the device under test 1, the flow of current in the reverse direction between the emitter and the collector of the IGBT 4 is suppressed, and the device under test 1 can be prevented from being broken.

  The diode element 8 has a breakdown voltage sufficiently higher than the breakdown voltage of the element 1 to be measured although the collector-emitter voltage VCE of the large element to be measured is applied in the reverse direction when the element 1 to be measured is turned off. Therefore, the junction breakage is prevented.

  FIG. 8 is a diagram showing current and voltage waveforms when the diode element 8 is not provided. In FIG. 8, the horizontal axis represents the time axis, the left vertical axis represents the voltage axis, and the right vertical axis represents the current axis. The straight line CI indicates the collector-emitter voltage VCE when the IGBT 4 is used as the element to be measured 1. The straight line CII indicates the current flowing through the main electrode (collector) of the IGBT of the element to be measured 1. The straight line CIII Indicates the current flowing through the clamp diode 15.

  As shown in FIG. 8, when the IGBT is turned off, as the current flowing through the main electrode of the IGBT 4 decreases, the current flowing through the clamp diode 15 once increases and then changes in the negative direction due to the recovery current. At this time, the collector voltage of the IGBT 4 falls to a negative voltage level lower than the ground voltage GND (0 V), and a negative surge voltage is generated. In accordance with the negative surge voltage, a current flows in the opposite direction (minus current) between the main electrodes (between collector and emitter) of the IGBT. After this, the collector current of the IGBT 4 flows in the positive direction again due to the current of the inductive load. Collector voltage rises. The collector voltage returns to a steady state after repeated oscillation.

  FIG. 9 shows current and voltage waveforms of the measurement circuit according to the first embodiment of the present invention. Also in FIG. 9, the horizontal axis represents the time axis, the left vertical axis represents the voltage axis, and the right vertical axis represents the current axis. Lines CI, CII and CIII show the same parameters as the curve shown in FIG. 8, ie, curve CI shows the collector-emitter voltage of the IGBT, curve CII is the current flowing between the main electrodes of the IGBT, A curve CIII shows the current flowing through the clamp diode 15.

  As shown in FIG. 9, when the IGBT is turned off, as the main electrode current of the IGBT indicated by the straight line CII decreases, the current flowing through the clamp diode 15 increases, and then a recovery current is generated (straight line CIII). Even if a recovery current is generated in the clamp diode 15, the collector-emitter voltage and the collector current indicated by the straight lines CI and CII instantaneously, as shown by the curve portion in the opposite direction, the negative voltage pulse and the main electrode current. However, no large negative voltage surge has occurred. The collector voltage of the IGBT 4 increases the ringing due to the inductive load 12, but does not reach the negative voltage, and can sufficiently suppress the reverse current between the collector and the emitter and suppress the generation of the negative surge voltage. Is clearly seen.

  As described above, according to the first embodiment of the present invention, the diode element is connected in antiparallel between the main electrodes of the measured element, and the negative surge voltage of the collector after the measured element is turned off is suppressed. It is possible to suppress malfunction during measurement, destruction of the element under measurement, and destruction of the clamp diode.

[Embodiment 2]
FIG. 10 is a diagram showing a configuration of the reverse bias safe operation region measuring apparatus according to the second embodiment of the present invention. The measurement circuit 2 shown in FIG. 10 differs from the measurement circuit 1 shown in FIG. 1 in the following points. That is, the Schottky diode 18 is used as a diode element connected in the reverse direction between the collector and the emitter of the device under test 1. The other configuration of the measurement circuit 2 shown in FIG. 10 is the same as that of the measurement circuit shown in FIG. 1, and corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  The Schottky diode 18 is an element that performs rectification by using a Schottky barrier between a metal and a semiconductor, and its junction capacitance is smaller than that of the PN diode, and the recovery current can be sufficiently reduced. Accordingly, after a current flows through the Schottky diode 18 in the state shown in FIG. 7, the current flowing from the Schottky barrier diode 18 through the capacitive load 12 is temporarily affected by the power supply voltage VCC of the main power supply 13. After reaching 0 A, a recovery current instantaneously flows, and it is considered that a positive surge is generated in the collector voltage of the device under test 1, and the measurement may be unstable. However, the Schottky diode 18 has a sufficiently small recovery current, can suppress the generation of such a positive surge voltage, can reduce the oscillation of the collector voltage shown in FIG. 9, and can perform stable measurement. .

  Note that the breakdown voltage of the Schottky diode 18 is sufficiently larger than the breakdown voltage of the element 1 to be measured. Further, as the anti-parallel diode, a diode having a small recovery current, that is, a low recovery diode can be used even if it is not the Schottky diode 18.

  As described above, according to the second embodiment of the present invention, the low recovery diode is connected in antiparallel between the collector and the emitter of the element to be measured, and the antiparallel diode is switched from the on state to the off state. The recovery current can be reduced, the occurrence of a positive surge can be suppressed, and stable measurement can be realized.

[Embodiment 3]
FIG. 11 shows a configuration of the measurement circuit according to the third embodiment of the present invention. In FIG. 11, no diode element is provided between the collector and emitter of the device under test 1. On the other hand, in the clamp circuit 10, a diode 20 is connected in the forward direction between the cathode of the clamp diode 15 and the clamp capacitor 17. That is, the diode 20 has an anode connected to the cathode of the clamp diode 15 and a cathode connected to the positive electrode of the capacitor 17. The other configuration of the measurement circuit shown in FIG. 11 is the same as that of the measurement circuit shown in FIG. 1, and corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  Most of the recovery current of the clamp diode 10 that causes a negative surge is supplied from the clamp capacitor 17. Therefore, the current supplied from the clamp capacitor 17 to the clamp diode 15 is cut off by connecting the diode 20 between the clamp diode 15 and the clamp capacitor 17 in the forward direction. At this time, the recovery current of the clamp diode 15 is given through the positive electrode of the clamp power supply 16. However, the clamp power supply 16 has an internal resistance, and the recovery current can be suppressed sufficiently low due to the influence of a voltage drop of the internal resistance.

  The anode of the diode 20 has the same potential as the positive electrode of the clamp power supply 16, and the cathode electrode has the same potential as the positive electrode of the clamp capacitor 17. Further, the positive electrode of the clamp power supply 16 and the positive electrode of the clamp capacitor 17 are almost at the same potential. Therefore, since only a small reverse bias voltage is applied to the reverse current prevention diode 20, an effect of sufficiently suppressing the recovery current of the clamp diode can be obtained even if a diode having a low rated voltage is used.

  As described above, according to the third embodiment of the present invention, the diode is connected in the forward direction between the clamp diode and the clamp capacitor in the clamp circuit. Therefore, the recovery current of the clamp diode can be suppressed, and a negative surge voltage caused by the recovery current can be prevented from occurring at the collector of the device under test 1.

[Embodiment 4]
FIG. 12 is a diagram showing a configuration of the reverse bias safe operation region measuring apparatus according to the fourth embodiment of the present invention. The measurement apparatus shown in FIG. 12 differs from the measurement apparatus shown in FIG. 11 in the following points. That is, in the clamp circuit 10 in the measurement circuit 2, the resistance element 22 is connected between the cathode of the clamp diode 15 and the positive electrode of the clamp capacitor 17 in parallel with the backflow prevention diode 20. The other configuration of the measurement apparatus shown in FIG. 12 is the same as that of the measurement apparatus shown in FIG. 11, and corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the measurement circuit 2 shown in FIG. 12, the clamp diode 15 performs a recovery operation after the device under test 1 is turned off. During this recovery operation, when a current flows from the clamp capacitor 17 to the clamp diode 15, the current is supplied to the clamp diode 15 via the resistance element 22. At this time, a voltage drop occurs due to the resistance value of the resistance element 22, and the energy of the recovery current injected into the clamp diode 15 is consumed by the voltage drop in the resistance element 22. Therefore, the recovery current of the clamp diode 15 is suppressed, and accordingly, a negative surge of the collector potential of the device under test 1 can be suppressed.

  Note that the resistance value of the resistance element 22 is made smaller than the internal resistance of the clamp power supply 16, and the recovery current is supplied from the clamp capacitor 17. Thereby, it is possible to prevent the clamp power supply 16 from being destroyed due to the clamp current being supplied exceeding the current capacity of the clamp power supply 16.

  As described above, in the fourth embodiment of the present invention, in the clamp circuit, the backflow preventing diode and the resistance element are connected in parallel between the clamp capacitor and the clamp diode. Therefore, the recovery current of the clamp diode can be suppressed, and the occurrence of negative surge can be suppressed accordingly. Further, by making the resistance value of the resistance element smaller than the internal resistance of the clamp power source, it is possible to suppress the current from flowing beyond the current capacity of the clamp power source, and to prevent the clamp power source from being destroyed.

[Embodiment 5]
FIG. 13 is a diagram showing a configuration of a reverse bias safe operation region measuring apparatus according to the fifth embodiment of the present invention. The measurement apparatus shown in FIG. 13 differs from the measurement apparatus shown in FIG. 12 in the following points. That is, in the clamp circuit 10, the second clamp capacitor 24 is provided between the resistance element 22 and the ground node separately from the clamp capacitor 17 connected to the backflow prevention diode 20. The other configuration of the measurement circuit 2 shown in FIG. 13 is the same as the configuration of the measurement circuit 2 shown in FIG. 12, and corresponding portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  The capacitance value of the second clamp capacitor 24 is made smaller than the capacitance value of the clamp capacitor 17. Therefore, when the recovery current for the clamp diode 15 flows from the second clamp capacitor 24 through the resistance element 22, the amount of flowing current can be further reduced, and accordingly, the collector of the device under test 1 is negatively charged. The occurrence of a surge can be suppressed. Further, the same effect as in the fourth embodiment can be obtained.

[Embodiment 6]
FIG. 14 shows a configuration of a reverse bias safe operation region measuring apparatus according to the sixth embodiment of the present invention. The measurement circuit 2 shown in FIG. 14 is different from the configuration of the measurement circuit shown in FIG. 13 in the following points. That is, in the clamp circuit 10, the series body of the resistance element 22 and the diode 26 is connected between the cathode of the clamp diode 15 and the ground node. The diode 26 has a cathode connected to the cathode of the clamp diode 15 and an anode connected to the resistor 22. The other configuration of the measurement circuit 2 shown in FIG. 14 is the same as the configuration of the measurement circuit 2 shown in FIG. 13, and the corresponding parts are denoted by the same reference numerals, and detailed description thereof is omitted.

  The resistance value of resistance element 22 is set to a resistance value smaller than the internal resistance of clamp power supply 16 as in the fourth and fifth embodiments. In the configuration shown in FIG. 14, the current flowing from the clamp power supply 16 into the resistor 22 is blocked by the diode 26. During the recovery operation of the clamp diode 15, the recovery current is supplied from the resistor 22 to the clamp diode 15 via the diode 26. In this case, similarly to the configuration shown in FIGS. 12 and 13, the recovery current can be reduced by the voltage drop of the resistance element 22. Further, since the clamp capacitor (17 or 24) is not connected to the resistance element 22, the recovery current of the clamp diode 15 can be further reduced as compared with the configuration of the fifth embodiment shown in FIG.

  As described above, in the sixth embodiment of the present invention, the recovery current of the clamp diode is suppressed by the backflow prevention diode and supplied via the resistance element and the diode. Therefore, the recovery current of the clamp diode can be further reduced, and the occurrence of a negative surge at the collector of the device under test 1 can be further suppressed.

  The reverse bias safe operation area measuring apparatus according to the present invention is applied to an apparatus for measuring a reverse bias safe operation area of a bipolar transistor or a power transistor having a bipolar operation such as an IGBT, thereby destroying an element to be measured and a clamp diode. Accurate measurement can be performed without any occurrence.

  DESCRIPTION OF SYMBOLS 1 Device under test, 2 Test circuit, 4 IGBT, 8 Diode element, 12 Inductive load, 13 Main power supply, 14 Main power supply capacitor, 15 Clamp diode, 16 Clamp power supply, 17 Clamp capacitor, 18 Schottky diode, 20 Backflow prevention Diode, 22 resistive element, 24 second clamp capacitor, 26 diode.

Claims (6)

An apparatus for measuring a reverse bias safe operating region of a transistor element having first and second main electrodes and a control electrode,
A diode element having a withstand voltage higher than the withstand voltage of the transistor element, connected in antiparallel between the first and second main electrodes of the transistor element, and a voltage of the first main electrode of the transistor element are clamped A reverse-bias safe operating area measuring device comprising a clamp circuit.   The reverse bias safe operation region measurement apparatus according to claim 1, wherein the diode element is a diode element having a small reverse recovery current. An apparatus for measuring a reverse bias safe operating region of a transistor element having first and second main electrodes and a control electrode,
Clamp power supply,
A clamp capacitor charged by a voltage generated by the clamp power supply;
A clamp diode connected between the first main electrode of the transistor element and the clamp power supply; and a backflow prevention diode connected in the same direction as the clamp diode between the clamp diode and the capacitor. Reverse bias safe operating area measuring device.   The reverse bias safe operation region measurement apparatus according to claim 3, further comprising a resistance element connected in parallel with the reverse current prevention diode.   The reverse bias safe operation area measuring device according to claim 3, further comprising a series body of a resistor and a second capacitor connected in parallel with the clamp power source.   The reverse bias safe operation region according to claim 3, further comprising a series body of a resistor and a second diode connected in parallel with the clamp power supply, wherein the second diode is connected in a reverse direction with respect to the clamp power supply. measuring device.

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