JP2010051165A - Gate drive circuit of semiconductor apparatus and power conversion apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gate drive circuit of a semiconductor apparatus having a simple circuit arrangement with a small number of parts and operating at a high speed and a low loss. <P>SOLUTION: In a drive circuit of a gate drive-type semiconductor element having a conductivity modulation effect, a gate drive circuit with a capacity 105 and a resistor 104 arranged in parallel is inserted between a gate and a switching output circuit 101. A high-speed ON operation is performed by applying a voltage equal to or higher than an ON threshold voltage of the semiconductor element to a gate terminal by dividing the voltage into a gate input capacity 106 and the capacity 105 of the semiconductor apparatus, and a current necessary for maintaining conductivity modulation is passed through the resistor of the gate circuit. Thereby, a gate drive circuit of a semiconductor apparatus having a simple circuit arrangement with a small number of parts and operating at a high speed and a low loss is provided positively using the gate capacity of the semiconductor element. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gate drive circuit of a semiconductor device having a semiconductor element as a main circuit mainly used in a power conversion device or the like.

  Conventionally, in a gate drive circuit of this type of semiconductor device, a gate drive switching circuit and a gate circuit of a main circuit transistor are connected by a resistor (see, for example, Patent Document 1).

  FIG. 6 shows a conventional gate drive circuit described in Patent Document 1. In FIG. As shown in FIG. 6, the insulated gate element 1, the gate resistor 2, the PNP transistor 3, the NPN transistor 4, the switching control circuit 5 for generating a switching control signal, and the gate capacitance by controlling the charge of the gate capacitance. The gate potential control circuit 6 optimizes the potential equivalently. The compatibility between gate drive and conductivity modulation in a gate drive semiconductor device is described in the same document.

JP 2003-70233 A JP 2004-247545 A

Morita et al., “650V 3.1 mΩcm 2 GaN-based Monolithic Bidirectional Switched Normal-off Gate Injection Transistor”; Electron Devices Meeting, 2007. IEDM 2007. (IEEE International; P865-868)

  However, the conventional configuration requires a gate potential control circuit to stabilize the gate potential, and requires charge current control to the gate in accordance with the gate potential, resulting in a large and complicated circuit scale. Had problems.

  The present invention solves the above-described conventional problems, and provides a gate drive circuit for a semiconductor device with a simple circuit configuration and a minimum number of components, and realizes driving that brings out the advantages of a wideband semiconductor. For the purpose.

  In order to solve the above conventional problems, the power conversion device of the present invention is turned on by applying a voltage equal to or higher than a threshold voltage, turned off at a voltage equal to or lower than the threshold voltage, and conductivity due to carrier injection from the gate to the channel when turned on. In a gate driving type semiconductor device having a modulation effect, a gate driving circuit in which a capacitor and a resistor are arranged in parallel is inserted between the gate and the switching output circuit, and the semiconductor device is divided by voltage division between the gate capacitance Cis and the capacitance Cg of the semiconductor device. A voltage equal to or higher than the ON threshold voltage is applied to the gate terminal.

As a result, when the switching control circuit output voltage is turned on, a gate voltage determined by the capacitance inversely proportional to the gate capacitance Cis and the capacitance Cg in the gate circuit is applied to the gate terminal of the semiconductor element, and when the threshold voltage is exceeded, high speed on Realize operation. Next, when turned on, a current (carrier injection) required to maintain conductivity modulation can be passed through the resistor of the gate circuit.

  As a result, it is possible to provide a gate drive circuit for a semiconductor device with high speed and low loss with a simple circuit configuration with a small number of components, actively utilizing the gate capacitance of the semiconductor element.

  In addition, it is possible to supply the necessary amount of carrier injection necessary to maintain conductivity modulation in the on state from the constant current supply means, and a gate drive circuit for a semiconductor device that operates more stably and at a high speed and low loss can be provided. Can be provided.

  Further, by providing the gate voltage limiting means at the gate terminal in this kind of GIT type gate drive semiconductor element, it is possible to prevent an excessive current from flowing into the gate, and particularly in the semiconductor device having a high speed and low loss at the time of off. A gate driving circuit can be provided.

  The present invention can provide a gate drive circuit of a semiconductor device that has a simple circuit configuration with a small number of parts and that is high speed and low loss.

1 is a configuration diagram of a gate drive circuit of a power conversion device according to Embodiment 1 of the present invention. The figure which shows the drive simulation result of the power converter device in Embodiment 1 of this invention Configuration diagram of gate drive circuit of power conversion device in embodiment 2 of the present invention Configuration diagram of gate drive circuit of power conversion device according to embodiments 3 and 4 of present invention Gate characteristic diagram of GIT transistor in the second embodiment of the present invention Configuration of gate drive circuit of conventional power converter

A first invention is a gate drive type semiconductor device which is turned on by applying a voltage equal to or higher than a threshold voltage, turned off at a voltage lower than the threshold, and having a conductivity modulation effect by injecting holes from the gate to the channel when turned on. Is inserted between the gate and the switching output circuit to determine the relationship between the gate capacitance Cis of the semiconductor element and the capacitance Cg (switching control circuit output voltage when on) ) × (Cg / (Cg + Cis)) ≧ (threshold voltage)
The gate drive circuit resistor supplies the current corresponding to the conductivity modulation to the gate of the gate drive type semiconductor device, so that the output voltage of the switching control circuit is appropriately divided and applied to the gate terminal of the semiconductor device. The gate drive circuit of the semiconductor device can be provided with a simple circuit configuration with a small number of parts that is applied to the gate electrode and actively uses the gate capacitance of the semiconductor element.

  The second invention is the first invention, in particular, in the gate drive circuit of the gate drive type semiconductor element, the middle point of the two gate drive switches (transistors) connected to the gate drive power supply and the gate drive type. A constant current supply circuit (for example, a constant current diode) connected to the gate of the semiconductor element is provided, and high-speed switching and stable drive control can be realized.

The third invention is the first invention, in particular, in the gate drive circuit of the gate drive type semiconductor element, the middle point of two switches (transistors) connected to the gate drive power supply and the gate drive type semiconductor element By providing one constant current supply circuit (constant current diode) in parallel with the capacitor Cg between the gate and the gate, the gate drive semiconductor element can be driven at high speed during on-switching, Since the gate current can be supplied at a constant current, heat generation loss of the circuit and the gate drive type semiconductor element can be reduced by supplying an appropriate gate current.

  The fourth invention is the first invention in particular, and a band gap is formed at a gate terminal of a gate drive type semiconductor element mainly composed of a group III-group compound semiconductor such as gallium nitride or a wide band semiconductor such as SiC. By limiting the gate voltage below a considerable voltage, the drive voltage can be reduced by setting the operating conditions below the rising voltage of the gate voltage-current characteristic that changes exponentially in the gate voltage-current characteristic. Can be realized.

  The fifth aspect of the invention is the first aspect of the invention. In particular, the gate application at the time of turning on the gate drive type semiconductor device mainly composed of a group III-group compound semiconductor such as gallium nitride or a wide band semiconductor such as SiC is applied. It is possible to realize stable driving and reduction in driving power by driving the voltage at a threshold voltage or more and a voltage corresponding to the band gap.

  The sixth invention is the first invention in particular, and the same effect can be obtained even if the gate drive type semiconductor element is composed of a wide band semiconductor such as SiC, and a low loss and high speed switch can be achieved with a simple circuit configuration. Can be realized.

  In the seventh aspect of the invention, in particular, by using the gate drive circuit of the semiconductor device of the first to sixth aspects of the invention for the power conversion device, a low-loss power conversion device can be realized with a simple circuit configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a configuration diagram of a gate drive circuit of a semiconductor device according to a first embodiment of the present invention.

  In FIG. 1, reference numeral 100 denotes a gate-driven semiconductor which is turned on by applying a voltage equal to or higher than a threshold voltage, turned off at a voltage lower than the threshold, and has a conductivity modulation effect by injecting carriers from the gate to the channel when turned on. It is an element and is driven based on a signal from the switching circuit 101. The switching circuit 101 generates a switching signal, and forms a gate circuit of the semiconductor element 100 with an NPN transistor 102 and a PNP transistor 103 that constitute a drive circuit, and a capacitor (Cg) 105 that constitutes a parallel circuit with the gate resistor 104. It is composed.

  The gate drive semiconductor element 100 is a GIT (Gate Injection Transistor) composed of a gallium nitride semiconductor shown in Non-Patent Document 1.

  The operation and operation of the gate drive circuit of the semiconductor device configured as described above will be described below.

  First, in this type of gate drive semiconductor device 100, a gate input capacitance component (Cis) 106 exists between a gate terminal (denoted as G) and a source terminal (denoted as S). This capacity component is generally expressed as Cies or Ciss, but has a capacity of about 1000 PF with a 600V withstand voltage of about 15 AGIT. The threshold voltage is about 1.2V.

  The power supply voltage of the switching control circuit 101 is 12V in the present embodiment, and the gate drive voltage when the semiconductor element 100 is on is set to about 7V in consideration of the voltage loss in the configuration circuit. Yes. The gate resistance is 1500Ω and the capacitor 105 is 670 pF.

That is, when the NPN transistor 102 is on, the 12V voltage is divided by the capacitor 105 and the gate input capacitance 106,
12V × 670pF ÷ (670pF + 1000pF) = 4.8V
Thus, the ON threshold voltage V of the gate drive type semiconductor device 100 becomes equal to or higher, and the ON operation is performed. Once turned on, the current 12V ÷ 1500A = 8 mA through the gate resistor 104.
Thus, a current is maintained to maintain conductivity modulation by gate current injection. By performing this conductivity modulation, the state of lower on-resistance can be maintained, so that a low-loss semiconductor device is realized.

  FIG. 2 shows a circuit simulation result in the configuration circuit in this embodiment. In FIG. 2, the gate voltage rises quickly during the switching operation, and the current is charged / discharged mainly through the capacitor 105. Further, it can be seen that the gate voltage is maintained at 7 V after the ON operation and the current value necessary for conductivity modulation (in this case, 8 mA) is maintained.

  In the absence of the capacitor 105, there is no effect in the steady on state. However, in the absence of the capacitor 105, the gate resistor 104 and the gate input capacitance 106 are charged with a time constant of about 1.5 ms. Since the circuit is configured, the transient state at the time of on / off is delayed, and the switching loss is increased. If the gate resistance is reduced, the transient state is accelerated, but the on-loss increases because the current required for conductivity modulation decreases. In other words, in the case of a gate drive circuit having only the gate resistor 104, the switching speed (loss) and the loss in the ON steady state are in a reciprocal state.

  As described above, in this embodiment, the gate drive circuit in the semiconductor element 100 is configured by the resistor 104 and the capacitor 105 in parallel, and the gate voltage determined by the capacitor 105 and the gate input capacitance 106 of the semiconductor element 100 is set as follows. By setting the threshold voltage or higher, a gate-on operation is performed at a high speed during switching, and an appropriate gate current can be supplied after the switch-on, so that a semiconductor device capable of high-speed switching with a low loss can be configured.

(Embodiment 2)
FIG. 3 shows a configuration diagram of the gate drive circuit of the semiconductor device according to the second embodiment of the present invention.

  In FIG. 3, reference numeral 110 denotes a GIT mainly composed of gallium nitride as shown in Non-Patent Document 1. On the other hand, the drive signal from the signal source 111 is connected via the drive buffer circuits 112 and 113 that drive the two gate drive switches 115 and 116 that are configured by transistors and perform complementary operations. Further, the gate drive switches 115 and 116 are connected to the gate drive power supply 114, and at the midpoint of connection thereof, a constant current supply circuit 117 composed of, for example, a constant current diode is connected to the gate of the transistor GIT110. In addition, the high resistor 118 is connected between the gate and the source of the gate to prevent inadvertent on operation.

  The on drive signal from the signal source 111 is amplified by the drive buffer circuit 112 and the switch 115 is turned on. On the other hand, since the drive buffer circuit 113 is a negative logic output, the switch 116 is turned off. Since the gate of the transistor GIT110 is connected to the gate driving power supply 114 via the constant current supply circuit 117, the gate current flows through the transistor GIT110 to be turned on. Looking at the transient state, until the switch 115 is turned on, the potential of the gate drive power supply 114 is determined by the junction capacitance component of the constant current diode of the constant current supply circuit 117 and the gate-source capacitance component of the transistor GIT110. A voltage that is inversely proportional to both capacitance values appears between the constant current diode of the constant current supply circuit 117 and the gate-source of the transistor GIT110, and a voltage is generated in the constant current diode of the constant current supply circuit 117. The constant current operation can be performed promptly, and the gate potential of the transistor GIT110 exceeds the threshold voltage at a very high speed with the same effect as in the first embodiment, so that a high-speed switching operation can be realized.

  Further, the off drive signal from the signal source 111 turns off the switch 115 because the drive buffer circuit 112 turns off the switch 115 and the drive buffer circuit 113 turns off the switch 116 and the switch 118. Then, since the gate of the transistor GIT110 is grounded, the gate potential of the transistor GIT110 is turned off because the gate current becomes zero potential.

  Since the gate-source connection of the transistor GIT110 has a diode characteristic, the voltage-current characteristic has an exponential characteristic with respect to the change of the gate voltage as shown in FIG. Thus, in driving the transistor GIT110, when constant voltage driving is performed, the driving current changes due to temperature changes, component variations, etc., and the operating point in conductivity modulation moves. However, by performing constant current driving, the gate-source voltage varies, but since there is no current change, a stable conductivity modulation operation can be ensured. For example, if the voltage rises when the temperature rises, the gate current decreases, the on-resistance between the source and drain of the transistor GIT110 also has a positive temperature characteristic, and the gate current decreases and the transistor loss increases, The operation is inconvenient in that loss increases. However, by performing constant current driving, a necessary amount of gate current is always supplied, so that such a problem is solved.

  In addition, since the gate-source is short-circuited by the high resistor 118 at the time of OFF, even when the drive power supply voltage fluctuates, even if the source-drain voltage of the transistor GIT110 is a change having a very large dv / dt. The semiconductor device is characterized in that a stable off state can be maintained.

(Embodiment 3)
FIG. 4 shows a configuration diagram of a gate drive circuit of a semiconductor device according to the third embodiment of the present invention. In the figure, the same components as those in FIG.

  In FIG. 4, reference numeral 119 denotes a capacitor having a function equivalent to that of the capacitor (Cg) 105 described in the first embodiment, and improves the switching speed at the time of ON. Further, a gate voltage limiting means 120 using a Zener diode connected between the gate and the source of the transistor GIT110 is connected.

Since the driving buffer circuit 112 turns on the switch 115 and the driving buffer circuit 113 has a negative logic output, the switch 116 is turned off. Then, the gate of the transistor GIT110 is connected to the gate driving power supply 114 via the constant current supply circuit 117, so that the gate current flows through the transistor GIT110 to be turned on. During the transition in which the switch 115 is turned on, the potential of the gate drive power supply 114 is divided between the capacitance component of the capacitor 119 and the gate-source capacitance component of the transistor GIT110, and the voltage is applied to the constant current diode of the constant current supply circuit 117. And constant current operation can be performed quickly. In addition, since the capacity distribution setting can be appropriately selected, the speed setting is easy.

  Further, the off drive signal from the signal source 111 turns the switch 116 on because the drive buffer circuit 112 turns off the switch 115 and the drive buffer circuit 113 has a negative logic output. Then, since the gate of the transistor GIT110 is grounded, the gate potential of the transistor GIT110 is turned off because the gate current becomes zero potential.

  In the gate drive circuit of the gate drive type semiconductor element, it is connected between the middle point of two switches (transistors) 115 and 116 connected to the gate drive power supply 114 and performing the complementary operation and the gate of the gate drive type semiconductor element 110. By providing the constant current supply circuit (constant current diode) 117 and the capacitor Cg capacitor 119 in parallel, the gate drive semiconductor element can be driven at a high speed during on-switching, and further, the gate current can be driven during the on-state. Can be supplied at a constant current, so that a circuit with an excessive gate current and a heat generation loss of a gate drive semiconductor element can be reduced.

(Embodiment 4)
FIG. 4 shows a configuration diagram of a gate driving circuit for a semiconductor device in the fourth embodiment of the present invention.

  In FIG. 4, by providing a voltage limiting means 120 with a Zener diode, a gate voltage equal to or lower than a voltage corresponding to a band gap (in this embodiment, a band gap of GaN of 3.4 V) is applied to the gate terminal of the gate driving type semiconductor device 110. As shown in FIG. 5, in the gate Vgs-Igs characteristic, the gate current value exponentially increases from about 5 V, but an excessive drive voltage is applied to the gate by mistake. As a result, the drive circuit loss and the gate loss that are generated can be reduced, and the loss can be reduced and the reliability can be improved.

  In this embodiment, a Zener diode is used as the gate voltage limiting means 120, but the same effect can be obtained even if other voltage limiting means are used. Further, the gate voltage limiting means 120 can achieve the same effect in the first and second embodiments, for example, and can be realized independently of the configuration of the gate drive circuit.

(Embodiment 5)
In the fifth embodiment of the present invention, the gate applied voltage when the gate drive semiconductor element is turned on is driven at a threshold voltage or higher and a voltage corresponding to a band gap or less without providing a voltage limiting means as in the fourth embodiment. By setting the gate drive power supply 114 so that it can be achieved, stable drive and reduction in drive power are realized in the same way.

  Since the gate-source connection of the transistor GIT110 has a diode characteristic, the voltage-current characteristic has an exponential characteristic with respect to the change of the gate voltage as shown in FIG. In the transistor GIT110 used in the above, since the gate current rapidly increases from about 5V and leads to circuit loss and gate loss, stable driving can be realized and driven by driving at a threshold voltage or higher and a predetermined voltage or lower in advance. The reduction of electric power is similarly realized (not shown).

As described above, the gate-source characteristics of the transistor GIT110 used in this embodiment are lower than the voltage corresponding to the bandgap, but the transistors having other physical property values have different voltage values.

  Further, the same effect can be obtained even when the semiconductor element 100 of the present embodiment is a transistor or other similar element composed of another wide band gap semiconductor such as a group III compound semiconductor or SiC, A low-loss high-speed switch can be realized with a simple circuit configuration with a small number of parts.

  As described above, the gate drive circuit of the semiconductor device according to the present invention can be a gate drive circuit of a low-loss semiconductor device with a simple circuit configuration. Therefore, the voltage drive semiconductor having conductivity modulation such as a power conversion device. The present invention can be widely applied to a gate drive circuit of a semiconductor device having an element as a main circuit.

100 Gate Drive Type Semiconductor Device 101 Switching Control Circuit 104 Resistor 105 Capacitance
106 Gate Capacitance of Semiconductor Element 110 GIT Transistor 111 Signal Source 112 Drive Buffer Circuit 113 Drive Buffer Circuit 114 Gate Drive Power Supply 115 Gate Drive Switch (Transistor)
116 Gate drive switch (transistor)
117 Constant current supply circuit (constant current diode)
118 Resistor 119 Capacitor 120 Gate voltage limiting means (Zener diode)

Claims (7)

Using a gate-driven semiconductor element that is turned on by applying a gate voltage higher than a threshold voltage, turned off at a voltage lower than the threshold voltage, and has a conductivity modulation effect by injecting carriers from the gate to the channel when turned on ,
A parallel circuit of a capacitor and a resistor is inserted between the gate and the output of the switching control circuit, and the relationship between the gate capacitance Cis of the semiconductor element and the capacitance Cg is expressed as (switching control circuit output voltage when ON) × (Cg / (Cg + Cis )) ≧ (Threshold voltage)
A gate drive circuit for a semiconductor device, wherein the resistor of the gate drive circuit supplies a current commensurate with conductivity modulation to the gate of the gate drive semiconductor element. The gate drive type semiconductor device is characterized in that constant current supply means is provided between a midpoint of two switches connected between gate drive power supplies and performing complementary operation and the gate of the gate drive type semiconductor device. A gate drive circuit for a semiconductor device according to claim 1. In the gate drive type semiconductor element, a constant current supply means is connected in parallel with the capacitor Cg between the midpoint potential of two switches connected to a gate drive power supply and performing a complementary operation and the gate of the gate drive type semiconductor element. The gate drive circuit for a semiconductor device according to claim 1, further comprising: The gate drive type semiconductor element is mainly composed of a group III-III compound semiconductor such as gallium nitride or a wide band semiconductor such as SiC, and a gate voltage at which a gate terminal applied voltage is approximately equal to or less than a band gap voltage. 2. The gate drive circuit for a semiconductor device according to claim 1, further comprising a limiting unit. The gate-driven semiconductor element is mainly composed of a group III-III compound semiconductor such as gallium nitride or a wide band semiconductor such as SiC, and the gate applied voltage at the time of ON is equal to or higher than a threshold voltage and is approximately equivalent to a band gap. The gate drive circuit for a semiconductor device according to claim 1, wherein the gate drive circuit is driven at a voltage equal to or lower than the voltage of the semiconductor device.   2. The gate drive circuit of a semiconductor device according to claim 1, wherein the gate drive type semiconductor element is mainly composed of a wide band semiconductor such as SiC. A power converter using the gate drive circuit of the semiconductor device according to claim 1.

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