US-12620987-B2 - Current gate driver for wide bandgap semiconductor transistor

US12620987B2US 12620987 B2US12620987 B2US 12620987B2US-12620987-B2

Abstract

A gate driver has a turn-on circuit and a turn-off circuit. The turn-on circuit pulls up a gate terminal of a wide bandgap (WBG) semiconductor transistor and turns on the WBG semiconductor transistor in response to a first status of an on-off control signal. The turn-off circuit pulls down the gate terminal of the WBG semiconductor transistor and turns off the WBG semiconductor transistor in response to a second status of the on-off control signal. When the on-off control signal transits to the first status, the turn-on circuit drives the gate terminal of the WBG semiconductor transistor at a first constant driving current, and later switches to a second constant driving current. The second constant driving current is lower than the first constant driving current.

Inventors

Abel Borras Serra

Assignees

MONOLITHIC POWER SYSTEMS, INC.

Dates

Publication Date: 20260505
Application Date: 20231218

Claims (20)

1 . A current gate driver for a wide bandgap (WBG) semiconductor transistor, comprising: an input terminal configured to receive an on-off control signal; an output terminal coupled to a gate terminal of the WBG semiconductor transistor; a turn-on circuit coupled to the output terminal, to drive the WBG semiconductor transistor by providing a gate current flowing into the gate terminal of the WBG semiconductor transistor via the output terminal in response to a first status of the on-off control signal; and a turn-off circuit coupled to the output terminal, to pull down the gate terminal of the WBG semiconductor transistor and turn off the WBG semiconductor transistor in response to a second status of the on-off control signal; wherein when the on-off control signal transits to the first status, the turn-on circuit is configured to drive the gate terminal of the WBG semiconductor transistor at a first constant driving current first, and later after a gate voltage of the WBG semiconductor transistor is charged to a maximum value, in response to the gate current dropping below a first threshold, the turn-on circuit switches and is configured to provide a second constant driving current to drive the gate terminal of the WBG semiconductor transistor, and the second constant driving current is lower than the first constant driving current.
2 . The current gate driver of claim 1 , wherein the turn-on circuit is configured to set the first constant driving current via a first resistor and configured to set the second constant driving current via a second resistor.
3 . The current gate driver of claim 1 , wherein the turn-on circuit further comprises: a current monitoring circuit, configured to monitor the gate current, and provide a current set signal accordingly; and a current delivering circuit coupled to a power supply, the current delivering circuit is configured to pull up the gate terminal of the WBG semiconductor transistor with one of the first constant driving current and the second constant driving current based on the current set signal and the on-off control signal.
4 . The current gate driver of claim 3 , wherein when the on-off control signal transits to the first status, the current delivering circuit is configured to provide the first constant driving current to drive the gate terminal of the WBG semiconductor transistor, and then in response to the current set signal, the current delivering circuit is configured to provide the second constant driving current to drive the gate terminal of the WBG semiconductor transistor.
5 . The current gate driver of claim 3 , wherein the current monitoring circuit further comprises: a comparison circuit, configured to receive a current sensing signal, and configured to provide the current set signal via comparing the current sensing signal with a second threshold, wherein the current sensing signal is capable of reflecting dropping of the gate current.
6 . The current gate driver of claim 1 , wherein the turn-on circuit further comprises: a first transistor having a collector coupled to a power supply, an emitter coupled to a first node, and a base coupled to the power supply through a switch, wherein the switch is turned on and off based on the on-off control signal; and a second transistor having a collector coupled to the base of the first transistor, an emitter coupled to a second node, and a base coupled to the emitter of the first transistor at the first node; wherein a first resistor and a second resistor are coupled between the first node and the second node, and the second node is coupled to the output terminal of the gate driver.
7 . The current gate driver of claim 6 , wherein the turn-on circuit further comprises: a comparison circuit, configured to compare a voltage across the base and the emitter of the second transistor with a third threshold, and the emitter of the first transistor and the base of the second transistor are configured to be selectively coupled to one of the first resistor and the second resistor based on a comparison result between the third threshold and the voltage across the base and the emitter of the second transistor.
8 . A gate driving method for a wide bandgap (WBG) semiconductor transistor, comprising: providing an output terminal coupled to a gate terminal of the WBG semiconductor transistor; using an input terminal for receiving an on-off control signal; using a turn-on circuit coupled to the output terminal for driving the WBG semiconductor transistor by providing a gate current flowing into the gate terminal of the WBG semiconductor transistor via the output terminal in response to a first status of the on-off control signal; using a turn-off circuit coupled to the output terminal for pulling down the gate terminal of the WBG semiconductor transistor and turning off the WBG semiconductor transistor in response to a second status of the on-off control signal; in response to a transition to the first status of the on-off control signal, causing the turn-on circuit to first drive a first constant driving current to the gate terminal of the WBG semiconductor transistor to turn on the WBG semiconductor transistor; later after a voltage of the gate terminal of the WBG semiconductor transistor is charged to a maximum value, in response to the gate current dropping below a first threshold, causing the turn-on circuit to automatically switch and be configured to provide and deliver a second constant driving current to the gate terminal of the WBG semiconductor transistor to keep the WBG semiconductor activated, wherein the second constant driving current is lower than the first constant driving current; and in response to the second status of the on-off control signal, pulling down the gate terminal of the WBG semiconductor transistor to turn off the WBG semiconductor transistor.
9 . The gate driving method of claim 8 , wherein the first constant driving current is established via a first resistor, and the second constant driving current is established via a second resistor.
10 . The gate driving method of claim 8 , further comprising: coupling a collector of a first transistor of the turn-on circuit to a power supply, and coupling a base of the first transistor of the turn-on circuit to the power supply through a switch; coupling a collector of a second transistor of the turn-on circuit to the base of the first transistor, coupling a base of the second transistor of the turn-on circuit to an emitter of the first transistor, and coupling an emitter of the second transistor of the turn-on circuit to the gate terminal of the WBG semiconductor transistor; and turning on and off the switch based on the on-off control signal.
11 . The gate driving method of claim 10 , further comprising: comparing a voltage across the base and the emitter of the second transistor of the turn-on circuit with a second threshold; and selectively coupling the emitter of the first transistor and the base of the second transistor of the turn-on circuit to one of a first resistor and a second resistor based on a comparison result between the second threshold and the voltage across the base and the emitter of the second transistor.
12 . A current gate driver, comprising: an input pin configured to receive an on-off control signal; a power supply pin configured to be coupled to a power supply; and a first output pin and a second output pin coupled to a gate terminal of a wide bandgap (WBG) semiconductor transistor; a turn-on circuit coupled to the second output pin, configured to drive the WBG semiconductor transistor by providing a gate current flowing into the gate terminal of the WBG semiconductor transistor via the second output pin in response to a first status of the on-off control signal; and a turn-off circuit coupled to the first output pin, configured to pull down the gate terminal of the WBG semiconductor transistor and turn off the WBG semiconductor transistor in response to a second status of the on-off control signal; wherein in response to a transition to the first status of the on-off control signal, the turn-on circuit of the gate driver is configured to first provide to the gate terminal of the WPG semiconductor transistor a first constant driving current via the second output pin first, and later after a gate voltage of the WBG semiconductor transistor is charged to a maximum value, in response to the gate current dropping below a first threshold, the turn-on circuit of the gate drive switches and is configured to provide a second constant driving current, lower than the first constant driving current, via the second output pin, to drive the gate terminal of the WBG semiconductor transistor; and wherein in response to the second status of the on-off control signal, the turn-off circuit of the gate driver is configured to pull down the gate terminal of the WBG semiconductor transistor via the first output pin.
13 . The current gate driver of claim 12 , further comprising: a third output pin coupled to the gate terminal of the WBG semiconductor transistor; wherein the second output pin is capable of being coupled to a first resistor to establish the first constant driving current; and wherein the third output pin is capable of being coupled to a second resistor to establish the second constant driving current.
14 . The current gate driver of claim 12 , wherein the second output pin is configured to be coupled to a first resistor and a second resistor, wherein the first resistor is used to establish the first constant driving current, and the second resistor is used to establish the second constant driving current.
15 . The current gate driver of claim 12 , wherein the second constant driving current is lower than the first constant driving current.
16 . The current gate driver of claim 12 , further comprising: a first transistor of the turn-on circuit having a collector coupled to the power supply, an emitter coupled to a first node, and a base coupled to the power supply through a switch, wherein the switch is turned on and off based on the on-off control signal; and a second transistor of the turn-on circuit having a collector coupled to the base of the first transistor, an emitter coupled to a second node, and a base coupled to the emitter of the first transistor at the first node; wherein a first resistor and a second resistor are coupled between the first node and the second node, and the second node is coupled to the output terminal of the gate driver.
17 . The current gate driver of claim 16 , further comprising: a comparison circuit, configured to compare a voltage across the base and the emitter of the second transistor of the turn-on circuit with a second threshold, and the emitter of the first transistor of the turn-on circuit and the base of the second transistor of the turn-on circuit are configured to be selectively coupled to one of the first resistor and the second resistor based on a comparison result between the threshold and the voltage across the base and the emitter of the second transistor.
18 . The current gate driver of claim 17 , wherein the second threshold is lower than the voltage across the base and the emitter of the second transistor of the turn-on circuit in full conduction.
19 . The current gate driver of claim 11 , wherein the second threshold is lower than the voltage across the base and the emitter of the second transistor of the turn-on circuit in full conduction.
20 . The current gate driver of claim 3 , wherein the current delivering circuit further comprises: a pull-up circuit; and a single-pole double-throw switch capable of coupling the pull-up circuit to the output terminal of the current gate driver via either a first resistor or a second resistor, wherein when the on-off control signal transits to the first status and in response to the current set signal, the turn-on circuit is configured to set the first constant driving current via the first resistor and configured to set the second constant driving current via the second resistor.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to electronic circuit, and more particularly but not exclusively relates to current gate driver for wide bandgap semiconductor transistor. 2. Description of Related Art Usually, conductivity between a drain terminal and a source terminal of a silicon power field effect transistor (FET) is controlled by a voltage applied between a gate terminal and the source terminal of the FET. The FET may be driven by a voltage gate driver that perform either as a voltage source to turn-on the FET or voltage sink to turn-off the FET. When driven, the gate terminal of the FET absorbs and releases electric charge in a way that could be modelled as a capacitor. Wide bandgap materials, such as gallium nitride (GaN), allows to create faster normally-off FET transistors when using several epitaxial architectures or combinations. GaN high electron mobility transistors (HEMTs) can be found in different architectures, such as HEMTs in a cascode configuration with a Si metal-oxide semiconductor field effect transistor (MOSFET), enhancement mode HEMTs, gate injection transistor (GIT), and so on. For HEMTs in a cascode configuration with a Si MOSFET, the gate behaves as a Silicon MOSFET which can be easily derived, but the overall transistor exhibits higher RONxQG and RONxEOSS than other configurations. Enhancement mode HEMTs exhibit better Figures of Merit (FOMs). However, Gate leakage current is injected to the semiconductor when the Gate voltage is higher than the equivalent diode forward voltage (VF) between the Gate and the channel. This Gate current injection is responsible of the current collapse phenomena which brings to a threshold voltage Vth shift and an on-resistance Ron degradation. GITs solve the problem of current collapse through hole injection. The gate of a GIT has an ohmic behavior, which is very rugged against over-voltage, due to the self-clamping nature of the equivalent diode between the gate and channel, but draws an excessive current which makes it difficult to drive. Thus, both the enhancement mode HEMTs and GITs require a different driver design. SUMMARY OF THE INVENTION It is one of the objects of the present invention to provide a current gate driver for wide bandgap semiconductor transistor. One embodiment of the present invention discloses a current gate driver for a wide bandgap (WBG) semiconductor transistor, comprising an input terminal, an output terminal, a turn-on circuit, and a turn-off circuit. The input terminal is configured to receive an on-off control signal. The output terminal is coupled to a gate terminal of the WBG semiconductor transistor. The turn-on circuit is coupled to the output terminal, to drive the WBG semiconductor transistor by providing a gate current flowing into the gate terminal of the WBG semiconductor transistor via the output terminal in response to a first status of the on-off control signal. The turn-off circuit is coupled to the output terminal, to pull down the gate terminal of the WBG semiconductor transistor and turn off the WBG semiconductor transistor in response to a second status of the on-off control signal. When the on-off control signal transits to the first status, the turn-on circuit is configured to drive the gate terminal of the WBG semiconductor transistor at a first constant driving current first, and later switch to a second constant driving current to drive the gate terminal of the WBG semiconductor transistor, and the second constant driving current is lower than the first constant driving current. Another embodiment of the present invention discloses a gate driving method for a WBG semiconductor transistor. Receiving an on-off control signal. In response to a first status of the on-off control signal, delivering a first constant driving current to a gate terminal of the WBG semiconductor transistor to turn on the WBG semiconductor transistor. After a voltage of the gate terminal of the WBG semiconductor transistor is charged at a maximum value, automatically switching to deliver a second constant driving current to the gate terminal of the WBG semiconductor transistor to keep the WBG semiconductor activated, wherein the second constant driving current is lower than the first constant driving current. In response to a second status of the on-off control signal, pulling down the gate terminal of the WBG semiconductor transistor to turn off the WBG semiconductor transistor. Yet another embodiment of the present invention discloses a current gate driver, comprising an input pin, a power supply pin, a first output pin, and a second output pin. The input pin is configured to receive an on-off control signal. The power supply pin configured to coupled to a power supply. The first output pin and the second output pin are coupled to a gate terminal of a WBG semiconductor transistor. In response to a first status of the on-off control signal, the gate driver is con