Dual-gate direct-drive circuit of depletion-mode wide-bandgap power device

Abstract

The present invention relates to the field of integrated circuits. Disclosed is a dual-gate direct-drive circuit of a depletion-mode wide-bandgap power device. A first gate controls the device to enter an on / off state, and a second gate controls a standby state of a system. The circuit comprises an isolated gate driving chip, an isolated transformer, a dual-gate wide-bandgap power device, and an enhancement-mode semiconductor device, wherein the second gate of the dual-gate wide-bandgap power device is connected to a source of the enhancement-mode semiconductor device, and a source of the dual-gate wide-bandgap power device is connected to a drain of the enhancement-mode semiconductor device. The dual-gate wide-bandgap power device comprises the first gate and the second gate of a spaced trench structure. The present invention realizes a forward-voltage direct-drive function of the depletion-mode power device, and also fully exerts high-frequency switching characteristics and high blocking voltage endurance capability of the wide-bandgap semiconductor material; and the depletion-mode wide-bandgap power device has high gate voltage working range, high gate reliability, low leakage current, and high reverse freewheeling capability.

Description

Dual-gate direct drive circuit for depletion-mode wide bandgap power devices Technical Field

[0001] The present invention relates to the technical field of integrated circuits, and in particular to a dual-gate direct drive circuit of a depletion-type wide-bandgap power device. Background Art

[0002] Wide bandgap semiconductors offer excellent properties such as a wider bandgap, higher critical breakdown voltage, high temperature resistance, and radiation resistance. Therefore, developing high-performance wide bandgap power devices can significantly increase the operating frequency and reliability of switching power supply systems, while significantly reducing system power consumption.

[0003] Power devices based on wide-bandgap semiconductor materials are categorized as enhancement-mode and depletion-mode. Enhancement-mode devices have a positive threshold voltage and a narrow gate voltage operating range (1V-6V), while depletion-mode devices have a negative threshold voltage, a wide gate voltage operating range, and higher current capabilities. Therefore, depletion-mode devices can more fully leverage the performance advantages of wide-bandgap semiconductor materials.

[0004] The existing gate voltage drive scheme for depletion-mode power devices is as follows:

[0005] 1. Cascode drive scheme. As shown in Figure 1, the cascode device cascades a low-voltage enhancement-mode power device with a depletion-mode power device, leveraging the positive threshold voltage of the enhancement-mode power device to achieve the normally-off characteristic of the cascode device. This scheme has a sufficient safe gate voltage operating range and a certain degree of gate immunity, but the device's switching characteristics are limited by the enhancement-mode power device and cannot fully utilize the high-frequency switching characteristics of the wide-bandgap power device.

[0006] 2. Negative voltage direct drive solution, as shown in Figure 2, requires designing a level conversion circuit between multiple power rails in the drive circuit to generate a negative gate drive voltage, which increases the complexity of system design and increases the static power consumption of the system.

[0007] Therefore, it is urgent to design a driving circuit that can fully utilize the performance advantages of depletion-mode wide-bandgap power devices and have high gate reliability.

[0008] Summary of the Invention

[0009] The present invention provides a dual-gate direct drive circuit for a depletion-type wide-bandgap power device, which realizes the positive voltage direct drive function of the depletion-type power device and fully utilizes the high-frequency switching characteristics and high blocking voltage resistance of wide-bandgap semiconductor materials. It has a high gate voltage operating range, high gate reliability, low leakage current and high reverse freewheeling capability.

[0010] An embodiment of the present invention provides a dual-gate direct drive circuit for a depletion-mode wide bandgap power device, comprising:

[0011] An isolated gate driver chip, wherein the IN terminal of the isolated gate driver chip is connected to the pulse source VPULSE, the VDDI terminal is connected to the VDC+ terminal of the input power supply, the VSSI terminal is connected to the VDC- terminal of the input power supply, the VDDO terminal is connected to the VCC+ terminal of the output power supply, the VSSO terminal is connected to the VCC- terminal of the output power supply, and the OUT terminal is connected to one end of the first resistor R1;

[0012] A dual-gate wide bandgap power device M1, comprising a first gate G1, a second gate G2, and an embedded first diode D1, wherein the first gate G1 is connected to the other end of the first resistor R1, the anode of the first diode D1 is connected to the second gate G2, and the cathode is connected to the drain of the dual-gate wide bandgap power device M1;

[0013] a second diode D2, wherein the anode of the second diode D2 is connected to the VDDO terminal of the isolated gate driver chip, and the cathode of the second diode D2 is connected to the source of the dual-gate wide bandgap power device M1;

[0014] An isolation transformer, wherein the VIN terminal of the isolation transformer is connected to the VDC+ terminal of the external power supply, the GND terminal is connected to the VDC- terminal of the external power supply, and the +VO terminal is connected to one end of the second resistor R2;

[0015] An enhancement-mode semiconductor device M2, wherein the gate of the enhancement-mode power device M2 is connected to the other end of the second resistor R2, the source is connected to the 0V end of the isolation transformer and the second gate G2 of the dual-gate wide bandgap power device M1, and the drain and the source of the dual-gate wide bandgap power device M1 are connected to the SW end.

[0016] In one embodiment of the present invention, when the isolated gate driver chip and the isolated transformer are in a powered-on state, the first gate G1 controls the dual-gate wide bandgap power device M1 to enter a switching working state;

[0017] When the isolated gate driver chip and the isolated transformer are in a standby state, the second gate G2 controls the dual-gate wide bandgap power device M1 to enter and maintain an off state.

[0018] In one embodiment of the present invention, when the input power supply VDC+ and the output power supply VCC+ are greater than or equal to the operating voltage, the isolated gate driver chip and the isolated transformer are in the power-on state, and the +VO terminal of the isolated transformer continuously outputs a high level, so that the enhancement mode semiconductor device M2 is in the normally open state, and the SW potential is equal to VCC+ minus the turn-on voltage V of the second diode D2. D2 (VCC+-V D2), the OUT terminal of the isolated gate driver chip outputs a pulse signal which is transmitted to the first gate G1 of the dual-gate wide bandgap power device M1, and the first gate G1 controls the dual-gate wide bandgap power device M1 to implement a switching logic function:

[0019] When the voltage of the first gate G1 is at a high level, the voltage difference between the first gate G1 and the source SW of the dual-gate wide bandgap power device M1 is zero, and the dual-gate wide bandgap power device M1 is turned on;

[0020] When the voltage of the first gate G1 is at a low level, the voltage difference between the first gate G1 and the source SW of the dual-gate wide bandgap power device M1 is a negative voltage (V D2 -VCC+), the dual-gate wide bandgap power device M1 is turned off.

[0021] In one embodiment of the present invention, when the input power supply VDC+ and the output power supply VCC+ are lower than the operating voltage, the isolated gate driver chip and the isolated transformer are in a standby state, the voltage difference between the gate and the source of the enhancement-mode semiconductor device M2 is zero, the dual-gate wide bandgap power device M1 maintains an off state, the potential of the SW terminal gradually rises from zero, the potential of the second gate G2 of the dual-gate wide bandgap power device M1 is zero, and the voltage difference between the second gate G2 and the source SW terminal of the dual-gate wide bandgap power device M1 gradually becomes negative. When the voltage difference is lower than the threshold voltage of the dual-gate wide bandgap power device M1, the dual-gate wide bandgap power device M1 enters and maintains an off state, and the potential of the SW terminal no longer increases.

[0022] In one embodiment of the present invention, the material of the enhancement mode semiconductor device M2 is one of Si, SiC, and GaN.

[0023] In one embodiment of the present invention, the first diode D1 is a Schottky diode.

[0024] In one embodiment of the present invention, the second diode D2 is a Schottky diode. When the input voltage VDC+ and the output voltage VCC+ are zero, the second diode D2 is used to block the current flowing from the SW end to the isolated gate driver chip and the output power supply VCC+.

[0025] In one embodiment of the present invention, the dual-gate wide bandgap power device M1 comprises a wide bandgap semi-insulating substrate layer (1), a wide bandgap unintentionally doped layer (2), and a wide bandgap N-type channel layer (3); a dielectric layer (4), a metal source electrode (5), and a metal drain electrode (6) are provided above the wide bandgap N-type channel layer (3); the first gate G1 is provided above the dielectric layer (4); the wide bandgap N-type channel layer (3) has an interval trench structure; the second gate G2 is provided above the trench structure; the second gate G2 is in direct contact with the top surface of the trench structure; the dielectric layer (4) is provided between the second gate G2 and the side surface and bottom surface of the trench structure; the second gate G2 is used to connect the source of the enhancement-mode semiconductor device M2.

[0026] In one embodiment of the present invention, the metal source electrode (5) and the metal drain electrode (6) form an ohmic contact with the wide bandgap N-type channel layer (3), the wide bandgap N-type channel layer (3) below the first gate G1 forms a Schottky contact, the second gate G2 forms a Schottky contact with the top surface of the trench structure in the wide bandgap N-type channel layer (3), and the second gate G2, the dielectric layer (4), and the side surface and bottom surface of the trench structure in the wide bandgap N-type channel layer (3) form a metal-insulator-semiconductor (MIS) structure.

[0027] In one embodiment of the present invention, the second gate G2, the wide bandgap N-type channel layer (3) and the metal drain electrode (5) form the first Schottky-type diode D1.

[0028] The dual-gate direct drive circuit of the depletion-mode wide bandgap power device according to the embodiment of the present invention has the following beneficial effects:

[0029] (1) Positive gate voltage direct drive function and high-frequency switching characteristics. The present invention can use conventional driver chips to achieve the positive gate voltage direct drive function of depletion-type wide bandgap power devices, while fully utilizing the high-frequency switching characteristics of wide bandgap power devices.

[0030] (2) Wide gate operating voltage range and high gate reliability. The output voltage range of the driver chip of the present invention is from 0V to the absolute value of the threshold voltage of the depletion-mode wide-bandgap power device, achieving a wide gate operating voltage range and enhancing the gate anti-interference capability.

[0031] (3) Low leakage current and high reverse freewheeling capability. The dual-gate wide bandgap power device M1 of the present invention benefits from the embedded metal insulator semiconductor (MIS) structure, which significantly reduces the leakage current of the M1 device. Thanks to the embedded Schottky diode D1, the reverse turn-on voltage of the M1 device is significantly reduced, thereby improving the reverse freewheeling capability of the M1 device.

[0032] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0034] FIG1 is a schematic diagram of a conventional negative voltage direct drive circuit for a depletion-mode wide bandgap power device;

[0035] FIG2 is a schematic diagram of an existing cascade drive circuit for a depletion-mode wide bandgap power device;

[0036] FIG3 is a schematic diagram of a dual-gate direct drive circuit of a depletion-mode wide bandgap power device proposed by the present invention;

[0037] FIG4 is a schematic structural diagram of a dual-gate depletion-mode wide bandgap device proposed in the present invention;

[0038] FIG5 is a schematic cross-sectional view of a dual-gate depletion-mode wide bandgap device along line AA' proposed by the present invention;

[0039] FIG6 is a schematic cross-sectional view of the dual-gate depletion-mode wide bandgap device proposed by the present invention along line BB′. DETAILED DESCRIPTION

[0040] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0041] The first embodiment of the present invention provides a dual-gate direct drive circuit for a depletion-mode wide bandgap power device. As shown in FIG3 , the dual-gate direct drive circuit for a depletion-mode wide bandgap power device includes:

[0042] An isolated gate driver chip, wherein the IN terminal of the isolated gate driver chip is connected to the pulse source VPULSE, the VDDI terminal is connected to the VDC+ terminal of the input power supply, the VSSI terminal is connected to the VDC- terminal of the input power supply, the VDDO terminal is connected to the VCC+ terminal of the output power supply, the VSSO terminal is connected to the VCC- terminal of the output power supply, and the OUT terminal is connected to one end of the first resistor R1;

[0043] A dual-gate wide bandgap power device M1, comprising a first gate G1, a second gate G2, and an embedded first diode D1, wherein the first gate G1 is connected to the other end of the first resistor R1, the anode of the first diode D1 is connected to the second gate G2, and the cathode is connected to the drain of the dual-gate wide bandgap power device M1;

[0044] a second diode D2, wherein the anode of the second diode D2 is connected to the VDDO terminal of the isolated gate driver chip, and the cathode of the second diode D2 is connected to the source of the dual-gate wide bandgap power device M1;

[0045] An isolation transformer, wherein the VIN terminal of the isolation transformer is connected to the VDC+ terminal of the external power supply, the GND terminal is connected to the VDC- terminal of the external power supply, and the +VO terminal is connected to one end of the second resistor R2;

[0046] Enhancement mode semiconductor device M2, the gate of the enhancement mode power device M2 is connected to the other end of the second resistor R2, the source is connected to the 0V end of the isolation transformer and the second gate G2 of the dual-gate wide bandgap power device M1, and the drain and the source of the dual-gate wide bandgap power device M1 are connected to the SW end.

[0047] In one embodiment of the present invention, the second gate G2 , the wide bandgap N-type channel layer 3 and the metal drain electrode 5 form a Schottky-type first diode D1 .

[0048] In one embodiment of the present invention, the material of the enhancement mode semiconductor device M2 is one of Si, SiC, and GaN.

[0049] In one embodiment of the present invention, the first diode D1 is a Schottky diode.

[0050] In one embodiment of the present invention, the second diode D2 is a Schottky diode. When the input voltage VDC+ and the output voltage VCC+ are zero, the second diode D2 is used to block the current flowing from the SW terminal to the isolated gate driver chip and the output power supply VCC+.

[0051] Based on the dual-gate direct drive circuit of the above embodiment, a second embodiment of the present invention proposes a specific structure of a dual-gate wide bandgap power device.

[0052] As shown in Figure 4, in one embodiment of the present invention, a dual-gate wide bandgap power device M1 includes a wide bandgap semi-insulating substrate layer 1, a wide bandgap unintentionally doped layer 2, a wide bandgap N-type channel layer 3, a dielectric layer 4, a metal source electrode 5 and a metal drain electrode 6 are provided above the wide bandgap N-type channel layer 3, a first gate G1 is provided above the dielectric layer 4, the wide bandgap N-type channel layer 3 has an interval trench structure, a second gate G2 is provided above the trench structure, the second gate G2 is in direct contact with the top surface of the trench structure, a dielectric layer 4 is provided between the second gate G2 and the side surface and bottom surface of the trench structure, and the second gate G2 is used to connect the source of the enhancement-mode semiconductor device M2.

[0053] As shown in Figures 5 and 6, in one embodiment of the present invention, the metal source electrode 5 and the metal drain electrode 6 form an ohmic contact with the wide bandgap N-type channel layer 3, the wide bandgap N-type channel layer 3 below the first gate G1 forms a Schottky contact, the second gate G2 forms a Schottky contact with the top surface of the trench structure in the wide bandgap N-type channel layer 3, and the second gate G2, the dielectric layer 4, and the side surface and bottom surface of the trench structure in the wide bandgap N-type channel layer 3 form a metal-insulated semiconductor structure MIS.

[0054] Specifically, the working principle of the dual-gate wide bandgap power device M1 is as follows:

[0055] When the first gate G1 or the second gate G2 is at a low level compared to the metal source electrode 4, that is, the voltage difference between the two is less than the threshold voltage of M1, the electrons in the wide bandgap N-type channel layer 3 are depleted, the M1 tube is turned off, and the embedded metal insulator gate semiconductor structure (MIS) reduces the off-leakage current of the device; when the first gate G1 and the second gate G2 are both at a high level compared to the metal source electrode 4, that is, the difference between the two is greater than the threshold voltage of M1, electrons accumulate in the wide bandgap N-type channel layer 3, and the M1 tube is turned on.

[0056] When the first gate G1 is at a low level compared to the metal source electrode 4, the second gate G2 is at a high level compared to the metal source electrode 4, and the metal drain electrode is at a low level, the parasitic Schottky diode D1 of the M1 tube is turned on, and the M1 tube enters the off-freewheeling working state.

[0057] According to the dual-gate direct drive circuit of the above-mentioned embodiment, the third embodiment of the present invention proposes a dual-gate direct drive scheme for a depletion-type wide bandgap power device. When the isolated gate drive chip and the isolated transformer are in the power-on state, the first gate G1 controls the dual-gate wide bandgap power device M1 to enter the switching working state; when the isolated gate drive chip and the isolated transformer are in the standby state, the second gate G2 controls the dual-gate wide bandgap power device M1 to enter and maintain the off state.

[0058] In one embodiment of the present invention, when the input power supply VDC+ and the output power supply VCC+ are greater than or equal to the operating voltage, the isolated gate driver chip and the isolated transformer are in the power-on state (Switching), and the +VO terminal of the isolated transformer continuously outputs a high level, so that the enhancement mode semiconductor device M2 is in a normally open state, and the SW potential is equal to VCC+ minus the turn-on voltage V of the second diode D2. D2 (VCC+-V D2 ), the OUT terminal of the isolated gate driver chip outputs a pulse signal which is transmitted to the first gate G1 of the dual-gate wide bandgap power device M1. The first gate G1 controls the dual-gate wide bandgap power device M1 to implement the switching logic function:

[0059] When the voltage of the first gate G1 is at a high level, the voltage difference between the first gate G1 and the source SW of the dual-gate wide bandgap power device M1 is zero, and the dual-gate wide bandgap power device M1 is turned on;

[0060] When the voltage of the first gate G1 is low, the voltage difference between the first gate G1 and the source SW of the dual-gate wide bandgap power device M1 is negative (V D2 -VCC+), the dual-gate wide bandgap power device M1 is turned off.

[0061] In one embodiment of the present invention, when the input power supply VDC+ and the output power supply VCC+ are less than the operating voltage, the isolated gate driver chip and the isolated transformer are in a standby state (Stand-by), the voltage difference between the gate and the source of the enhancement-mode semiconductor device M2 is zero, the dual-gate wide bandgap power device M1 maintains the off state, the potential of the SW terminal gradually rises from zero, the potential of the second gate G2 of the dual-gate wide bandgap power device M1 is zero, and the voltage difference between the second gate G2 and the source SW terminal of the dual-gate wide bandgap power device M1 gradually becomes negative. When the voltage difference is less than the threshold voltage of the dual-gate wide bandgap power device M1, the dual-gate wide bandgap power device M1 enters and maintains the off state, and the potential of the SW terminal no longer increases.

[0062] According to an embodiment of the present invention, a dual-gate direct drive circuit for a depletion-type wide bandgap power device is proposed. The first gate controls the device to enter a switching state, and the second gate controls the system's standby state. The circuit includes an isolated gate drive chip, an isolated transformer, a dual-gate wide bandgap power device, and an enhancement-type semiconductor device, wherein the second gate of the dual-gate wide bandgap power device is connected to the source of the enhancement-type semiconductor device, and the source of the dual-gate wide bandgap power device is connected to the drain of the enhancement-type semiconductor device. The dual-gate wide bandgap power device includes a first gate and a second gate of an interval trench type. The present invention realizes the positive voltage direct drive function of the depletion-type power device, while giving full play to the high-frequency switching characteristics and high blocking voltage withstand capability of the wide bandgap semiconductor material, and has a high gate voltage operating range, high gate reliability, low leakage current, and high reverse freewheeling capability.

[0063] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0064] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "N" means at least two, such as two, three, etc., unless otherwise specifically defined.

Claims

1. A dual-gate direct drive circuit for a depletion-mode wide bandgap power device, characterized in that: include: An isolated gate driver chip, wherein the IN terminal of the isolated gate driver chip is connected to the pulse source VPULSE, the VDDI terminal is connected to the VDC+ terminal of the input power supply, the VSSI terminal is connected to the VDC- terminal of the input power supply, the VDDO terminal is connected to the VCC+ terminal of the output power supply, the VSSO terminal is connected to the VCC- terminal of the output power supply, and the OUT terminal is connected to one end of the first resistor R1; A dual-gate wide bandgap power device M1, comprising a first gate G1, a second gate G2, and an embedded first diode D1, wherein the first gate G1 is connected to the other end of the first resistor R1, the anode of the first diode D1 is connected to the second gate G2, and the cathode is connected to the drain of the dual-gate wide bandgap power device M1; a second diode D2, wherein the anode of the second diode D2 is connected to the VDDO terminal of the isolated gate driver chip, and the cathode of the second diode D2 is connected to the source of the dual-gate wide bandgap power device M1; An isolation transformer, wherein the VIN terminal of the isolation transformer is connected to the VDC+ terminal of the external power supply, the GND terminal is connected to the VDC- terminal of the external power supply, and the +VO terminal is connected to one end of the second resistor R2; An enhancement-mode semiconductor device M2, wherein the gate of the enhancement-mode power device M2 is connected to the other end of the second resistor R2, the source is connected to the 0V end of the isolation transformer and the second gate G2 of the dual-gate wide bandgap power device M1, and the drain and the source of the dual-gate wide bandgap power device M1 are connected to the SW end.

2. The dual-gate direct drive circuit according to claim 1, wherein: When the isolated gate driver chip and the isolated transformer are in a powered-on state, the first gate G1 controls the dual-gate wide bandgap power device M1 to enter a switching working state; When the isolated gate driver chip and the isolated transformer are in a standby state, the second gate G2 controls the dual-gate wide bandgap power device M1 to enter and maintain an off state.

3. The dual-gate direct drive circuit according to claim 2, characterized in that: When the input power supply VDC+ and the output power supply VCC+ are greater than or equal to the operating voltage, the isolated gate driver chip and the isolated transformer are in the power-on state, and the +VO terminal of the isolated transformer continuously outputs a high level, so that the enhancement mode semiconductor device M2 is in the normally open state, and the SW potential is equal to VCC+ minus the turn-on voltage V of the second diode D2. D2 (VCC+-V D2 ), the OUT terminal of the isolated gate driver chip outputs a pulse signal which is transmitted to the first gate G1 of the dual-gate wide bandgap power device M1, and the first gate G1 controls the dual-gate wide bandgap power device M1 to implement a switching logic function: When the voltage of the first gate G1 is at a high level, the voltage difference between the first gate G1 and the source SW of the dual-gate wide bandgap power device M1 is zero, and the dual-gate wide bandgap power device M1 is turned on; When the voltage of the first gate G1 is at a low level, the voltage difference between the first gate G1 and the source SW of the dual-gate wide bandgap power device M1 is a negative voltage (V D2 -VCC+), the dual-gate wide bandgap power device M1 is turned off.

4. The dual-gate direct drive circuit according to claim 2, wherein: When the input power supply VDC+ and the output power supply VCC+ are lower than the operating voltage, the isolated gate drive chip and the isolated transformer are in a standby state, the voltage difference between the gate and the source of the enhancement-mode semiconductor device M2 is zero, the dual-gate wide bandgap power device M1 maintains an off state, the potential of the SW end gradually rises from zero, the potential of the second gate G2 of the dual-gate wide bandgap power device M1 is zero, and the voltage difference between the second gate G2 and the source SW end of the dual-gate wide bandgap power device M1 gradually becomes negative. When the voltage difference is lower than the threshold voltage of the dual-gate wide bandgap power device M1, the dual-gate wide bandgap power device M1 enters and maintains an off state, and the potential of the SW end no longer increases.

5. The dual-gate direct drive circuit according to claim 1, wherein: The material of the enhancement mode semiconductor device M2 is one of Si, SiC and GaN.

6. The dual-gate direct drive circuit according to claim 1, wherein: The first diode D1 is a Schottky diode.

7. The dual-gate direct drive circuit according to claim 1, wherein: The second diode D2 is a Schottky diode. When the input voltage VDC+ and the output voltage VCC+ are zero, the second diode D2 is used to block the current flowing from the SW end to the isolated gate driver chip and the output power supply VCC+.

8. The dual-gate direct drive circuit according to claim 1, wherein: The dual-gate wide bandgap power device M1 comprises a wide bandgap semi-insulating substrate layer (1), a wide bandgap unintentionally doped layer (2), and a wide bandgap N-type channel layer (3); a dielectric layer (4), a metal source electrode (5), and a metal drain electrode (6) are provided above the wide bandgap N-type channel layer (3); the first gate G1 is provided above the dielectric layer (4); the wide bandgap N-type channel layer (3) has an interval trench structure; the second gate G2 is provided above the trench structure; the second gate G2 is in direct contact with the top surface of the trench structure; the dielectric layer (4) is provided between the second gate G2 and the side surface and bottom surface of the trench structure; the second gate G2 is used to connect the source of the enhancement-mode semiconductor device M2.

9. The dual-gate direct drive circuit according to claim 8, characterized in that: The metal source electrode (5) and the metal drain electrode (6) form an ohmic contact with the wide bandgap N-type channel layer (3); the wide bandgap N-type channel layer (3) below the first gate G1 forms a Schottky contact; the second gate G2 forms a Schottky contact with the top surface of the trench structure in the wide bandgap N-type channel layer (3); and the second gate G2, the dielectric layer (4), and the side surface and bottom surface of the trench structure in the wide bandgap N-type channel layer (3) form a metal-insulator-semiconductor (MIS) structure.

10. The dual-gate direct drive circuit according to claim 1, wherein: The second gate G2, the wide bandgap N-type channel layer (3) and the metal drain electrode (5) form the first Schottky-type diode D1.

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