Gallium nitride driving circuit

Abstract

The invention discloses a gallium nitride driving circuit which is used for generating driving voltage for driving a gallium nitride transistor. The circuit comprises a gallium nitride switching tube, an upper switching tube, a lower switching tube, a clamping module, an energy collection module, a diode, a capacitor, a clamping and logic driving module and a bias voltage generation module. The gallium nitride switch tube is connected with the drain electrode of the gallium nitride transistor and clamps the drain electrode voltage to a first voltage; the clamping module receives the first voltage and clamps the first voltage to a second voltage; the energy collection module receives the second voltage and the PWM signal and generates a power supply voltage and a stable voltage. The clamping and logic driving module receives a power supply voltage and a PWM signal and generates a pull-down driving signal. The bias voltage generation module receives the stable voltage and the pull-down driving signal and outputs a bias voltage. When the PWM signal is at a high level, the pull-down driving signal is at a low level, the bias voltage is at a high level, and the driving voltage is at a high level; when the PWM signal is at a low level, the pull-down driving signal is at a high level, the bias voltage is at a low level, and the driving voltage is at a low level.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and particularly to a gallium nitride drive circuit. Background Art

[0002] Many modules inside a gallium nitride drive chip need to be powered to work properly. Currently, most chips have reserved power supply pins, and a power supply voltage needs to be provided in the application to supply power to the chip separately, which increases the application complexity.

[0003] Due to certain parasitic inductances in the chip traces and package wire bonds of the device itself, and there are also certain parasitic inductances in the PCB layout of the drive chip and the power device in the system application. During the switching process, the parasitic inductances of the drive loop and the power loop will cause the gate signal of the device to oscillate, and severely will cause the gallium nitride device to be mis-triggered and thus lead to device failure. Since the typical gate drive voltage of a PGAN gallium nitride enhanced device is 6V and the typical threshold voltage of the device is 1.5V, it is easy to be mis-triggered by slight oscillation. Summary of the Invention

[0004] This application provides a gallium nitride drive circuit for generating a drive voltage to drive a gallium nitride transistor, including: a gallium nitride switch connected to the drain of the gallium nitride transistor for clamping the voltage of the drain to a first voltage; an upper switch; a lower switch connected to the upper switch; a clamping module connected to the gallium nitride switch, receiving the first voltage and clamping it to a second voltage; an energy harvesting module for receiving the second voltage and a PWM signal and generating a power supply voltage and a stable voltage; a diode connected to the energy harvesting module; a capacitor connected to the energy harvesting module; a clamping and logic drive module connected to the lower switch, receiving the power supply voltage and the PWM signal for generating a pull-down drive signal; a bias voltage generation module connected to the upper switch, receiving the stable voltage and the pull-down drive signal and outputting a bias voltage; wherein, when the PWM signal is at a high level, the pull-down drive signal is at a low level, the bias voltage output by the bias voltage generation module is at a high level, and the drive voltage is at a high level; when the PWM is at a low level, the pull-down drive signal is at a high level, the bias voltage output by the bias voltage generation module is at a low level, and the drive voltage is at a low level.

[0005] In one embodiment, the diode and the capacitor supply electrical energy alternately via the PWM signal and the second voltage to maintain the power supply voltage and the stable voltage.

[0006] In one embodiment, there are a plurality of series diodes between the output terminal of the clamping module and the ground terminal, and the clamping module determines the output clamping voltage value via the number of the series diodes.

[0007] In one embodiment, a pull-down transistor is provided between the output terminal and the ground terminal of the bias voltage generation module. The pull-down transistor is controlled by a pull-down drive signal output by the clamping and logic drive module. When the pull-down drive signal is at a high level, the bias voltage output by the bias voltage generation module is at a low level, and the drive voltage is at a low level; when the pull-down drive signal is at a low level, the bias voltage output by the bias voltage generation module is at a high level, and the drive voltage is at a high level.

[0008] This application provides a gallium nitride drive circuit for generating a drive voltage for driving a gallium nitride transistor, including: an upper switching transistor; a lower switching transistor connected to the upper switching transistor; an energy harvesting module for receiving the PWM signal and generating a supply voltage and a stable voltage; a diode connected to the energy harvesting module; a capacitor connected to the energy harvesting module; a clamping and logic drive module connected to the lower switching transistor, receiving the supply voltage and the PWM signal, and generating a pull-down drive signal; a bias voltage generation module connected to the upper switching transistor, receiving the stable voltage and the pull-down drive signal, and outputting a bias voltage; wherein, when the PWM signal is at a high level, the pull-down drive signal is at a low level, the bias voltage generation module outputs a high level, and the drive voltage is at a high level; when the PWM is at a low level, the pull-down drive signal is at a high level, the bias voltage generation module outputs a low level, and the drive voltage is at a low level.

[0009] In one embodiment, the energy harvesting module has a fast charging module that charges the diode and the capacitor during the first rising period of the PWM signal. When the charging is completed, the fast charging module is turned off, and the slow charging branch of the energy harvesting module is used to maintain the supply voltage VDD and the stable voltage VZ.

[0010] In one embodiment, the bias voltage generation module has a supplementary circuit for generating an output signal for the bias voltage generation module before the stable voltage is established.

[0011] In one embodiment, it further includes a suppression module for suppressing the transient voltage change generated when the gallium nitride transistor is turned off. The suppression module is connected to the drain of the gallium nitride transistor, the gate of the gallium nitride transistor, and the gate of the lower switching transistor.

[0012] In one embodiment, when the transient voltage change generated during the turn-off process of the gallium nitride transistor exceeds a preset value, the suppression module turns on the lower switching transistor.

[0013] In one embodiment, the suppression module includes a resistor-capacitor circuit and a second pull-down transistor. The second pull-down transistor is connected to the gate of the gallium nitride transistor. When the transient voltage change generated during the turn-off process of the gallium nitride transistor exceeds a preset value, the resistor-capacitor circuit generates an induced voltage to turn on the second pull-down transistor.

[0014] Through the above embodiments, the present application realizes the function of directly driving and powering with a wide range of control voltages, and does not require an additional power supply to power the drive circuit, while solving the technical problem of accidental turn-on of power devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Through the following description of the embodiments of the present application with reference to the drawings, the above and other objects, features, and advantages of the present application will become clearer: Figure 1 It is a circuit diagram of the gallium nitride drive circuit according to an embodiment of the present application.

[0016] Figure 2 It is a circuit diagram of the drive module according to an embodiment of the present application.

[0017] Figure 3 It is a circuit diagram of the core module according to an embodiment of the present application.

[0018] Figure 4 It is a circuit diagram of the clamping module according to an embodiment of the present application.

[0019] Figure 5 It is a circuit diagram of the energy harvesting module according to an embodiment of the present application.

[0020] Figure 6 is a circuit diagram of the bias voltage generation module according to an embodiment of the present application.

[0021] Figure 7 It is a circuit diagram of the clamping and logic drive module according to an embodiment of the present application.

[0022] Figure 8 It is a circuit diagram of the drive module according to an embodiment of the present application.

[0023] Figure 9 It is a circuit diagram of the core module according to an embodiment of the present application.

[0024] Figure 10 It is a circuit diagram of the energy harvesting module according to an embodiment of the present application.

[0025] Figure 11 It is a circuit diagram of the fast charging module according to an embodiment of the present application.

[0026] Figure 12 It is a circuit diagram of the bias voltage generation module according to an embodiment of the present application.

[0027] Figure 13Circuit diagram of the drive module according to an embodiment of the present application.

[0028] Figure 14 Circuit diagram of the core module according to an embodiment of the present application.

[0029] Figure 15 Circuit diagram of the suppression module according to an embodiment of the present application.

[0030] Figure 16 Circuit diagram of the bias voltage generation module according to an embodiment of the present application.

[0031] Figure 17 Transfer characteristic curve for the test of the present application.

[0032] Figure 18 Switching waveform test diagram according to an embodiment of the present application.

[0033] Figure 19 Hysteresis waveform test diagram according to an embodiment of the present application. Detailed implementation manners

[0034] As described above, the embodiments of the present application do not describe all details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the above description. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present application, so that those skilled in the art can make good use of the present application and its modifications based on the present application. The present application is only limited by the claims and their full scope and equivalents.

[0035] Figure 1 An embodiment of the gallium nitride drive circuit of the present application includes a gallium nitride transistor 100, a drive module 200, a gate 101 of the gallium nitride transistor 100, a drain 102 of the gallium nitride transistor 100, and a source 103 of the gallium nitride transistor 100. The drive module 200 is respectively connected to the gate 101, the drain 102, and the source 103. The drive module 200 receives a PWM signal. In one embodiment, the drive module 200 can be connected to a Kelvin source SK (Kelvin source).

[0036] Figure 2 An embodiment of the drive module 200 of the present application includes a core module 300, an electrostatic protection (ESD) module 350, a gallium nitride switch 351, a pull-down resistor 352, a diode 353, and a capacitor 354. The core module 300 is connected to the drain 102 via the gallium nitride switch 351. The pull-down resistor 352 is disposed between the gate 101 of the gallium nitride transistor 100 and the ground. Two ends of the capacitor 354 are respectively connected to the core module 300 and the source 103. Two ends of the diode 353 are respectively connected to the core module 300 and the source 103.

[0037] In one embodiment, the gallium nitride switching transistor 351 is a high-voltage depletion-mode power device, and the diode 353 is a zener diode. The drain of the gallium nitride switching transistor 351 is connected to the drain 102 of the gallium nitride transistor 100. The gate of the gallium nitride switching transistor 351 is grounded. The gallium nitride switching transistor 351 is used to clamp the power supply voltage to a first voltage. When the gallium nitride transistor 100 is turned off, the voltage of the drain 102 is the power supply voltage. The source voltage of the gallium nitride switching transistor 351 is clamped at the threshold voltage of the gallium nitride switching transistor 351, and in one embodiment, the threshold voltage ranges between 20 - 100V.

[0038] As Figure 3 shown is an embodiment of the core module 300 of the present application. The core module 300 includes a clamping module 400, an energy harvesting module 500, a bias voltage module 600, a clamping and logic driving module 700, enhancement-mode gallium nitride devices 492 / 493 / 494 / 495 / 496 / 497, an upper switching transistor 493, and a lower switching transistor 492.

[0039] The drain of the upper switching transistor 493 inputs a PWM signal. The drain of the lower switching transistor 492 is connected to the source of the upper switching transistor 493. The connection terminal of the upper switching transistor 493 and the lower switching transistor 492 is the output terminal of the driving voltage VG. The clamping module 400 is connected to the gallium nitride switching transistor 351 for performing secondary clamping. The clamping module 400 receives the first voltage clamped by the gallium nitride switching transistor 351 and clamps the first voltage to a second voltage. The diode 353 is connected to the energy harvesting module 500. The capacitor 354 is connected to the energy harvesting module 500. The energy harvesting module 500 receives the power supply voltage and the PWM signal and generates a supply voltage VDD and a stable voltage VZ. The clamping and logic driving module 700 is connected to the lower switching transistor 492. The clamping and logic driving module 700 receives the supply voltage VDD and the PWM signal and generates a pull-down driving signal SNK_DRV. The bias voltage generation module 600 is connected to the upper switching transistor 493. The bias voltage generation module 600 outputs a corresponding bias voltage VBIAS according to the received stable voltage VZ and the pull-down driving signal SNK_DRV.

[0040] When the PWM signal is at a high level, the bias voltage VBIAS output from the output terminal 302 of the bias voltage generation module 600 is at a high level, thereby controlling the upper switching transistor 493 to turn on, and the driving voltage VG is at a high level. When the PWM signal is at a low level, the bias voltage generation module 600 is at a low level, thereby controlling the upper switching transistor 493 to turn off, and the driving voltage VG is at a low level. Therefore, a stable driving signal VG for the gallium nitride transistor 100 can be obtained through the upper switching transistor 493 with the PWM signal.

[0041] The function of the circuit composed of the enhanced gallium nitride devices 494 / 495 / 496 / 497 is to suppress the voltage spike at the gate 101 of the gallium nitride transistor. The voltage spike can conduct and cause malfunction of the gallium nitride transistor 100. Therefore, eliminating the voltage spike can ensure that the gate 101 of the gallium nitride transistor obtains a stable voltage signal, thereby increasing the reliability of the gallium nitride transistor 100.

[0042] Figure 4 This is an embodiment of the clamping module 400 of the present application, including resistors 420 and enhanced gallium nitride devices 421 / 422 / 423 / 424 / 425 / 426 / 427 / 428 / 429. There are a plurality of series diodes 428 / 429 between the clamping voltage output terminal of the clamping module 400 and the ground terminal. The clamping module 400 determines the output clamping voltage (i.e., the second voltage) VCLAMP via the number of series diodes. In the embodiment of the present application, only two series diodes are taken as an example, and the number of series can be adjusted according to actual needs in practical applications.

[0043] Figure 5 This is an embodiment of the energy harvesting module 500 of the present application, including resistors 552 / 553 / 554 / 563 / 567 / 571 / 568 / 572, depletion-mode gallium nitride devices 553 / 564 / 569 / 570, and enhanced gallium nitride devices 551 / 550 / 555 / 557 / 558 / 559 / 560 / 561 / 562 / 565 / 573 / 566 / 574 / 575 / 576 / 517.

[0044] The diode 353 and the capacitor 354 are supplied with electrical energy alternately via the PWM signal and the second voltage VCLAMP to maintain the stability of the supply voltage VDD and the stable voltage VZ. When the PWM signal is at a high level, the gallium nitride transistor 100 conducts, and the drain of the gallium nitride transistor 100 is at a low level. At this time, the PWM signal is provided by the PWM signal port 104 for charging. When the PWM signal is at a low level, the gallium nitride transistor 100 is turned off, and the drain voltage is at a high level. At this time, the drain voltage of the gallium nitride transistor 100 is used for charging.

[0045] Figure 6 This is an embodiment of the bias voltage generation module 600 of the present application, including resistors 652 / 655 / 661 / 662 / 666 / 667, depletion-mode gallium nitride devices 650 / 653, capacitors 657 / 659 / 664 / 665, and enhancement-mode gallium nitride devices 651 / 654 / 656 / 658 / 660 / 663 / 668 / 669 / 670. The bias voltage generation module 600 inputs a stable voltage VZ and a pull-down drive signal SNK_DRV, and outputs a corresponding bias voltage signal VBIAS.

[0046] The enhancement-mode gallium nitride device 663 serves as a pull-down transistor, and the gate of the enhancement-mode gallium nitride device 663 is driven by the pull-down drive signal SNK_DRV. When the PWM signal is at a low level, the pull-down drive signal SNK_DRV is at a high level. At this time, the enhancement-mode gallium nitride device 663 is turned on, directly pulling down the output terminal 302 of the bias voltage generation module 600 to ground, making the output bias voltage VBIAS at a low level, turning off the upper switch transistor 493, and making the drive voltage VG at a low level, turning off the gallium nitride transistor 100.

[0047] Capacitors 664 / 665, resistors 666 / 667, and enhancement-mode gallium nitride devices 668 / 669 / 670 form a transient spike clamping circuit for suppressing voltage spikes at the output terminal 302 of the bias voltage generation module 600. During the process of the PWM signal changing from a low level to a high level, the output bias voltage VBIAS also changes from a low level to a high level. Due to capacitive coupling in the circuit, the output bias voltage VBIAS may have voltage spikes. Since there is a reliability risk when the gate voltage of the gallium nitride device is too high, eliminating the voltage spikes of the bias voltage VBIAS helps improve the reliability of the gallium nitride device.

[0048] Figure 7 This is an embodiment of the clamping and logic drive module 700 of the present application, including resistors 752 / 762 / 764 / 765 / 766 / 769 / 772 / 774 / 775 / 782 / 784 / 791, depletion-mode gallium nitride devices 750 / 761 / 768 / 771 / 773 / 781 / 790. Enhancement-mode gallium nitride devices 751 / 753 / 754 / 755 / 756 / 757 / 758 / 759 / 760 / 763 / 767 / 770 / 776 / 777 / 779 / 783 / 785 / 786 / 787 / 788 / 792 / 794 / 793.

[0049] The clamping and logic driving module 700 includes a clamping module, an input hysteresis logic module, and a driving module. The clamping and logic driving module 700 receives a PWM signal and a supply voltage VDD, and outputs a sink driving signal SNK_DRV. When the PWM signal is high, the sink driving signal SNK_DRV is low, the bias voltage generation module 600 outputs a high bias voltage VBIAS, and the driving voltage VG is high. When the PWM is low, the sink driving signal SNK_DRV is high, the bias voltage generation module 600 outputs a low bias voltage VBIAS, and the driving voltage VG is low.

[0050] Figure 8 This is an embodiment of the driving module 1200 of the present application, which includes a core module 1300, an electrostatic protection (ESD) module 350, a pull-down resistor 352, a diode 353, a capacitor 354, a first pull-down transistor 355, a second pull-down transistor 357, and a resistor 356. The pull-down resistor 352 is disposed between the gate 101 of the gallium nitride transistor 100 and the ground. Both ends of the capacitor 354 are respectively connected to the core module 1300 and the source 103 of the gallium nitride transistor 100. Both ends of the diode 353 are respectively connected to the core module 1300 and the source 103 of the gallium nitride transistor 100. In one embodiment, the diode 353 is a zener diode. The first pull-down transistor 355, the second pull-down transistor 357, and the resistor 356 form a pull-down module, and the pull-down module is disposed between the gate 101 of the gallium nitride transistor 100 and the PWM signal port 104. When the supply voltage VDD is not established, the pull-down module can pull down the gate terminal 101 of the gallium nitride transistor 100 to ensure that the gallium nitride transistor 100 will not be accidentally turned on.

[0051] Figure 9 This is an embodiment of the core module 1300 of the present application. Figure 9 The core module 1300 of Figure 3 differs from the core module 300 of

[0052] Figure 10 This is an embodiment of the energy harvesting module 1500 of the present application. The energy harvesting module 1500 is composed of a fast charging module 1550 and a slow charging branch. Figure 11 This is an embodiment of the fast charging module 1550. In this embodiment, the energy harvesting module 1500 only harvests the PWM signal to supply power to the capacitor 354 and the diode 353 to maintain a stable supply voltage VDD and a stable voltage VZ, and enables the supply voltage VDD to be fully established in the first switching waveform to ensure normal device function. To ensure normal device function in the first switching waveform.

[0053] The function of the fast charging module 1550 of the energy harvesting module 1500 is to quickly charge the diode 353 and the capacitor 354 during the rising edge of the first pulse of the PWM signal, so as to quickly establish the supply voltage VDD and the stable voltage VZ. After the charging is completed, the fast charging module 1550 is turned off, and then the slow charging branch of the energy harvesting module 1500 is used to maintain the supply voltage VDD and the stable voltage VZ.

[0054] Figure 12 This is an embodiment of the bias voltage generation module 1600 of the present application. Figure 12 The embodiment of Figure 6 The embodiment adds a supplementary circuit. The supplementary circuit includes transistors 1654 / 1657 / 1658 / 1659 and resistors 1655 / 1656. The function of the supplementary circuit is that when the stable voltage VZ is not established, this circuit can supply power to the bias voltage generation module 1600 to ensure the normal logic of the output bias voltage VBIAS.

[0055] Figure 13 This is an embodiment of the drive module 2200 of the present application. Figure 14 This is an embodiment of the core module 2300 of the present application. As Figure 13 shown, the difference between the drive module 2200 and Figure 8 the drive module 1200 is that an inhibition module 2800 is added to the core module 2300. As Figure 14 shown, the inhibition module 2800 is used to inhibit the transient voltage change dv / dt. When the transient voltage change dv / dt of the drain 102 of the gallium nitride transistor 100 is too large during the turn-off process, the drive signal provided by the inhibition module 2800 turns on the lower switch transistor 492 and pulls the gallium nitride transistor 100 to the ground to ensure that the gallium nitride transistor 100 is turned off.

[0056] Figure 15 This is an embodiment of the inhibition module 2800. The input signals of the inhibition module 2800 include the drive signal 718, the signal of the drain of the gallium nitride transistor 100, and the signal of the gate of the gallium nitride transistor 100. The transistor 2851 and the resistor 2856 in the inhibition module form an RC circuit. When there is a large transient voltage change dv / dt on the drain during the turn-off process of the gallium nitride transistor 100, the RC circuit will generate a transient current, and the transient current will generate an induced voltage on the branch 2801 through the resistor 2856. When the voltage of the branch 2801 is greater than the threshold voltage of the transistor 2858, the transistor 2858 conducts and pulls the gate of the gallium nitride transistor to the ground. The function of the transistor 2852 is that when the gallium nitride transistor 100 is in the on state, it pulls the branch 2801 to the ground and turns off the function of the 2800 module.

[0057] Figure 16 For an embodiment of the bias voltage generation module 2600, compared with the bias voltage generation module 1600 of Figure 11 , it is simplified in circuit, and the functions are the same as those of the bias voltage generation module 1600 of Figure 11 .

[0058] As Figure 17 shown is the transfer characteristic curve of the test of this application, and the device threshold voltage of 4V can be obtained.

[0059] As Figure 18 shown is the switch waveform test diagram of the embodiment of this application. When the voltage range of the PWM signal is 0 - 10V, the gate voltage of the gallium nitride transistor 101 is 0 - 5.6V, the stable voltage VZ is 5V, and the supply voltage VDD is 4.5V; when the voltage range of the PWM signal is 0 - 20V, the gate voltage of the gallium nitride transistor 101 is 0 - 6.4V, the stable voltage VZ is 5V, and the supply voltage VDD is 5.5V.

[0060] As Figure 19 shown is the hysteresis waveform test diagram of the embodiment of this application. It can be seen that the gallium nitride device has a hysteresis function, and the hysteresis voltage is 1V. From the overall test results, the gallium nitride device operates normally.

[0061] According to the embodiments of this application as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, according to the above description, many modifications and variations can be made. The purpose of selecting and specifically describing these embodiments in this specification is to better explain the principle and practical application of this application, so that those skilled in the art can make good use of this application and its modifications based on this application. This application is only limited by the claims and their full scope and equivalents.

Claims

1. A gallium nitride driving circuit for generating a driving voltage for driving a gallium nitride transistor, comprising: A gallium nitride switch tube, connected to the drain of the gallium nitride transistor, and used to clamp the voltage of the drain to a first voltage; Upper switch tube; The lower switch tube is connected to the upper switch tube; A clamping module, connected to the gallium nitride switch tube, receiving the first voltage, and clamping it to a second voltage; An energy collection module, used for receiving the second voltage and the PWM signal, and generating a supply voltage and a stable voltage; A diode connected to the energy collection module; A capacitor connected to the energy collection module; A clamping and logic driving module, connected to the lower switch tube, receiving the power supply voltage and the PWM signal, and used to generate a pull-down driving signal; A bias voltage generating module is connected to the upper switch tube, receives the stable voltage and the pull-down driving signal, and outputs a bias voltage; Among them, when the PWM signal is at a high level, the pull-down drive signal is at a low level, the bias voltage output by the bias voltage generating module is at a high level, and the drive voltage is at a high level; when the PWM is at a low level, the pull-down drive signal is at a high level, the bias voltage output by the bias voltage generating module is at a low level, and the drive voltage is at a low level.

2. The gallium nitride driving circuit according to claim 1, wherein the diode and the capacitor supply electric energy alternately via a PWM signal and the second voltage to maintain a supply voltage and a stable voltage. 3 . The gallium nitride driving circuit according to claim 1 , wherein a plurality of series diodes are provided between the output end of the clamping module and the ground end, and the clamping module determines the output clamping voltage value according to the number of the series diodes.

4. The gallium nitride driving circuit according to claim 1, wherein the bias voltage generating module is provided with a pull-down tube between the output terminal and the ground terminal, and the pull-down tube is controlled by the pull-down driving signal output by the clamping and logic driving module, and when the pull-down driving signal is at a high level, the bias voltage output by the bias voltage generating module is at a low level, and the driving voltage is at a low level; when the pull-down driving signal is at a low level, the bias voltage output by the bias voltage generating module is at a high level, and the driving voltage is at a high level.

5. A gallium nitride driving circuit for generating a driving voltage for driving a gallium nitride transistor, comprising: Upper switch tube; The lower switch tube is connected to the upper switch tube; An energy collection module, used for receiving the PWM signal and generating a power supply voltage and a stable voltage; A diode connected to the energy collection module; A capacitor connected to the energy collection module; A clamping and logic driving module is connected to the lower switch tube, receives the power supply voltage and the PWM signal, and generates a pull-down driving signal; A bias voltage generating module is connected to the upper switch tube, receives the stable voltage and the pull-down driving signal, and outputs a bias voltage; Among them, when the PWM signal is at a high level, the pull-down drive signal is at a low level, the bias voltage generating module outputs a high level, and the drive voltage is at a high level; when the PWM is at a low level, the pull-down drive signal is at a high level, the bias voltage generating module outputs a low level, and the drive voltage is at a low level.

6. The gallium nitride driving circuit according to claim 5, wherein the energy collection module has a fast charging module, which charges the diode and the capacitor during the first rising period of the PWM signal, and when the charging is completed, the fast charging module is turned off, and the slow charging branch of the energy collection module 1500 is used to maintain the power supply voltage VDD and the stable voltage VZ. 7 . The gallium nitride driving circuit according to claim 5 , wherein the bias voltage generating module has a supplementary circuit for generating an output signal for the bias voltage generating module before the stable voltage is established.

8. The GaN driving circuit according to claim 5, further comprising a suppression module for suppressing transient voltage changes generated when the GaN transistor is turned off, wherein the suppression module is connected to the drain of the GaN transistor, the gate of the GaN transistor and the gate of the lower switch tube.

9. The gallium nitride driving circuit according to claim 8, wherein: When the transient voltage variation generated by the gallium nitride transistor during the shutdown process exceeds a preset value, the suppression module turns on the lower switch tube.

10. The gallium nitride driving circuit according to claim 8, wherein: The suppression module includes a resistor-capacitor circuit and a second pull-down tube, wherein the second pull-down tube is connected to the gate of the gallium nitride transistor. When the transient voltage change generated by the gallium nitride transistor during the shutdown process exceeds a preset value, the resistor-capacitor circuit generates an induced voltage to turn on the second pull-down tube.

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