Gallium nitride device driving power supply regulation and control circuit and method

Abstract

The invention discloses a gallium nitride device driving power supply regulation and control circuit and method. The circuit comprises four modules, namely a rectangular wave generating module, a filtering module, a grid driving module and a power module. The rectangular wave generation module uses a low-cost 555 chip to generate rectangular waves below 2MHz. And the filtering module converts the rectangular waves into direct current meeting requirements and can provide certain current in combination with an operational amplifier. The grid driving module is powered by direct current generated by the filtering module, and the duty ratio and the switching frequency of the gallium nitride transistor grid driving power supply can be flexibly adjusted by adjusting resistance and capacitance values. The power module is a specific circuit applied by the gallium nitride transistor. According to the invention, flexible regulation and control of the gate driving power supply are realized by using the low-cost 555 chip, degradation of parameters such as threshold voltage and on resistance of the gallium nitride transistor in different working modes can be inhibited, and the stability and reliability of the gallium nitride transistor during operation in a circuit are improved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor devices, and relates to a control circuit and method for a driving power supply of a gallium nitride device. Background Art

[0002] Gallium nitride power devices have been widely used in power conversion circuits due to their advantages of high frequency, high voltage and high temperature resistance. Currently, there are two main types of normally-off gallium nitride high electron mobility transistors used commercially, namely the cascode switch structure and the p-type gallium nitride gate high electron mobility transistor structure (p-GaN gate HEMT). Among them, the p-type gallium nitride gate high electron mobility transistor structure (p-GaN gate HEMT) has a relatively small parasitic inductance and is widely used.

[0003] However, due to defects introduced during material growth and device fabrication, the threshold voltage of the p-GaN gate HEMT drifts and the on-resistance degrades after being subjected to drain voltage stress and gate voltage stress, reducing the performance of the p-GaN gate HEMT and the circuit system. Therefore, when the gallium nitride device operates under different drain voltages, gate voltage stresses and temperatures, different gate drive voltages are required to suppress performance degradation. In addition, gallium nitride transistors of different brands have different threshold voltages and different gate drive voltage ranges. Therefore, it is necessary to design a control circuit for the driving power supply of a gallium nitride device to meet the driving requirements of transistors under different brands and different operating modes, and to maximize the advantages of gallium nitride transistors such as high frequency, high voltage resistance and low on-resistance. Summary of the Invention

[0004] In view of the unstable threshold voltage of the p-GaN gate HEMT, the present invention proposes a driving idea of changing the driving voltage of the p-GaN gate HEMT under different operating states, and discloses a control circuit and method for a driving power supply of a gallium nitride device. The method of the present invention can effectively suppress the problem of threshold voltage drift of gallium nitride transistors, prevent device performance degradation, and improve the stability and reliability of the device when operating in high-frequency circuits. Its characteristics are that it does not use digital chips such as single-chip microcontrollers and DSPs, and does not require code programming. A low-cost, high-precision and easy-to-control driving power supply is realized based on an analog circuit.

[0005] The object of the first aspect of the present invention is to provide a control circuit for a gallium nitride device driving power supply. The circuit includes 4 modules, namely a rectangular wave generation module, a filtering module, a gate driving module, and a power module. Among them, the rectangular wave generation module uses a first-stage 555 chip to generate a rectangular wave below 2 MHz. The filtering module converts the rectangular wave into direct current and combines an operational amplifier to increase the output current on the premise that the voltage value of the direct current remains unchanged. The gate driving module uses the direct current generated by the filtering module as the power supply, and adjusts the duty cycle and switching frequency of the gate driving signal of the gallium nitride transistor by adjusting the values of the resistors and capacitors provided in the gate driving module. The power module is a power application circuit including a gallium nitride transistor, and the gate driving signal of the gallium nitride transistor is adjusted by the gate driving module.

[0006] Further, the rectangular wave generation module includes a first-stage 555 chip, resistors R1, R2, R3, diodes D1, D2, capacitors C1, C2. Among them, the common connection point where resistor R1 and R2 are connected is connected to the 7th pin of the first-stage 555 chip and the anode of diode D1. The other end of resistor R1 is connected to the 4th pin, 8th pin of the first-stage 555 chip and V CC is connected. The other end of resistor R2 is connected to the cathode of diode D2. The anode of diode D2 is connected to one end of resistor R3 and the 2nd pin and 6th pin of the first-stage 555 chip. The other end of resistor R3 is connected to the cathode of diode D1. The common connection point where capacitor C1 and C2 are connected is connected to the 1st pin of the first-stage 555 chip and grounded. The other end of capacitor C1 is connected to the sliding end of resistor R3. The other end of capacitor C2 is connected to the 5th pin of the first-stage 555 chip. The 3rd pin of the first-stage 555 chip is connected to the filtering module.

[0007] The described rectangular wave generation module uses a first-stage 555 chip operating in the multivibrator mode to output a rectangular wave, and uses resistors R1, R2, R3 and capacitor C1 to control the period and duty cycle of the rectangular wave. Diodes D1, D2 improve the flexibility of duty cycle adjustment.

[0008] Further, the filtering module includes resistors R4, R5, inductor L1, capacitor C3 and an operational amplifier. Among them, one end of inductor L1 is connected to one end of resistor R4. The other end of inductor L1 is connected to capacitor C3, one end of resistor R5 and the non-inverting input terminal of the operational amplifier. The other ends of capacitor C3 and resistor R5 are connected and grounded. The inverting input terminal and the output terminal of the operational amplifier are connected to the gate driving module. The other end of resistor R4 is connected to the 3rd pin of the first-stage 555 chip.

[0009] Further, the gate drive module includes a second-stage 555 chip, resistors R6, R7, R8, diodes D3, D4, and capacitors C4, C5. Among them, the common connection point where resistor R6 and R7 are connected is connected to pin 7 of the second-stage 555 chip and the anode of diode D3. The other end of resistor R6 is connected to pin 4 and pin 8 of the second-stage 555 chip and the output terminal of the operational amplifier of the filtering module. The other end of resistor R7 is connected to the cathode of diode D4. The anode of diode D4 is connected to one end of resistor R8 and pins 2 and 6 of the second-stage 555 chip. The other end of resistor R8 is connected to the cathode of diode D3. The common connection point where capacitors C4 and C5 are connected is connected to pin 1 of the second-stage 555 chip and grounded. The other end of capacitor C4 is connected to the sliding end of resistor R8. The other end of capacitor C5 is connected to pin 5 of the second-stage 555 chip. The drive chip is connected to the second-stage 555 chip and the power module.

[0010] The described gate drive module uses the direct current power supplied by the filtering module as the power supply, and uses the second-stage 555 chip of this module to generate the control signal required by the gate drive chip. According to the experimental needs, the second-stage 555 chip is set to work in the multivibrator mode, monostable mode or flip-flop mode. When the second-stage 555 chip works in the multivibrator mode, resistors R6, R7, R8 and capacitor C4 are used to control the period and duty cycle of the drive waveform, and output the drive waveform that meets the design requirements. The gate drive chip is used to amplify the output current capacity of the drive waveform to control the turn-on and turn-off of the subsequent gallium nitride transistor.

[0011] Further, the power module includes resistor R9 and the device under test, the gallium nitride transistor. Resistor R9 is connected to the drain of the gallium nitride transistor. The source and gate of the gallium nitride transistor are connected to the drive chip.

[0012] The object of the second aspect of the present invention is to provide a method for regulating the drive power supply of a gallium nitride device, which is realized by the gallium nitride device drive power supply regulation circuit described in the present invention, and includes the following steps:

[0013] The first step is to determine the optimal gate drive voltage of the gallium nitride transistor. First, determine the actual working state of the transistor, and then obtain the threshold voltage drift of the gallium nitride device based on the device manual or the actual test of the device's dynamic transfer curve, and then adjust the gate drive voltage according to the threshold voltage drift.

[0014] The second step is to generate the required direct current power. First, set the resistance and capacitance values of the rectangular wave generation module to adjust the duty cycle and frequency of the rectangular wave. Then, set the resistance, inductance, and capacitance values of the filtering module to convert the rectangular wave into direct current power, and use the voltage follower function of the operational amplifier to convert this direct current power into loadable direct current power, and use this direct current power to supply power to the second-stage 555 chip and the drive chip.

[0015] In the third step, various types of pulse waveforms that meet the requirements are output and connected to the gate of the gallium nitride transistor to be tested as drive signals. The working mode of the chip is set using the second-stage 555 chip, and the resistance and capacitance values of the gate drive module are determined, thereby obtaining various types of pulse signals to control the gate drive chip.

[0016] Beneficial effects:

[0017] 1. The present invention realizes low-cost and high-precision drive voltage regulation based on analog circuits.

[0018] 2. The present invention can suppress the adverse effects of threshold voltage drift and on-resistance degradation of gallium nitride transistors, and improve the stability of gallium nitride transistors when operating in a circuit. Description of the Drawings

[0019] The present invention will be better understood from the following description, which relates to a preferred embodiment given by way of non-limiting example and explained with reference to the accompanying schematic diagrams, in which:

[0020] Figure 1 is a schematic diagram of the structure of a gallium nitride transistor.

[0021] Figure 2 is a schematic diagram of the pulse voltage when the gallium nitride transistor is under drain voltage stress during circuit operation.

[0022] Figure 3 is a schematic diagram of the dynamic transfer curve of the gallium nitride transistor under different drain voltage stresses.

[0023] Figure 4 is the threshold voltage value of the gallium nitride transistor under different drain voltage stresses.

[0024] Figure 5 is a schematic diagram of the circuit principle for regulating the drive power supply of a gallium nitride device.

[0025] Figure 6 is a flowchart of the method for regulating the drive power supply of a gallium nitride device.

[0026] Figure 7 is a reference circuit when driving the transistor with a 6V gate voltage.

[0027] Figure 8 is simulated using Cadence software Figure 7 The waveforms of key nodes at 60 ms steady state of the circuit. Specific Embodiments

[0028] The following further describes the present invention in detail with reference to the drawings. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] Specifically, in the description of the present application, the orientation or positional relationship indicated by terms such as "one end" and "the other end" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. Unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0030] As Figure 1 shown, the structure of the gallium nitride transistor includes a substrate, a gallium nitride buffer layer, a two-dimensional electron gas channel layer, a barrier layer, a dielectric layer, a gate, a source, a gate, and a drain from bottom to top. The substrate serves as the supporting material for the gallium nitride transistor. The gallium nitride buffer layer is used to reduce the diffusion of the two-dimensional electron gas in the direction of the substrate. The barrier layer is used to polarize and generate the two-dimensional electron gas in the channel layer. The dielectric layer regulates the concentration of the two-dimensional electron gas under the gate. The source, drain, and gate are the three electrodes of the gallium nitride transistor. When the gallium nitride transistor operates as a switch, the gate voltage is used to control the opening and closing of the two-dimensional electron gas channel under the gate. Along with the switching process of the gallium nitride transistor, the gate and drain of the gallium nitride transistor will continuously withstand pulsed voltage stress. Due to the relatively high defect density of the gate dielectric layer of the gallium nitride transistor, carrier capture and de-capture processes will occur in the gate dielectric layer when the gallium nitride transistor operates as a switch, resulting in unstable threshold voltage of the transistor. At present, it is difficult to reduce the defect density of the gate dielectric layer in the production process and solve the problem of threshold voltage drift.

[0031] Figure 2 is a schematic diagram of the pulsed voltage when simulating the gallium nitride transistor under the drain voltage stress in the circuit operating state. In the off state, the drain voltage is the bus voltage. According to the circuit experiment requirements and the rated drain voltage of the transistor, the drain voltage stress borne by the transistor may be from 0 to several thousand volts. Existing gallium nitride transistors have different gate drive voltage ranges, and when the transistor is subjected to voltage stress, the threshold voltage drifts. At this time, the transistor requires different gate voltages to drive the transistor to obtain the best operating performance, and the gate drive voltage is generally 5 - 8V. As Figure 2As shown, first, a drain voltage stress is applied for a certain duration according to the operating state of the transistor in the circuit. Subsequently, the drain voltage of the transistor is switched to a test voltage, which is generally 0.1 - 1V. Then, a pulse voltage sequence is applied to the gate of the transistor to measure the "dynamic transfer curve" of the transistor. The gate voltage is an increasing pulse voltage, and the data sampling points are from the plateau region (at 75% of the pulse signal) after the pulse signal stabilizes. Analyzing the dynamic transfer curve of the transistor can obtain key parameters such as the threshold voltage and on-resistance of the transistor.

[0032] Figure 3 It is a schematic diagram of the dynamic transfer curve of a gallium nitride transistor under different drain voltage stresses. According to experimental requirements, the degradation of the transistor's dynamic parameters under different drain voltage stress durations can be studied. Figure 3 The voltage stress time in the schematic diagram is 1s. Here, the constant current method is used to extract the threshold voltage, and the gate voltage when the current in the dynamic transfer curve is equal to 1mA is taken as the threshold voltage. It can be seen that as the drain voltage stress increases, the measured dynamic transfer characteristic curve gradually drifts forward (to the right), and the threshold voltage drift amount also continuously increases. Subsequently, by adjusting the magnitude of the gate drive voltage, the threshold voltage drift amount is compensated.

[0033] Figure 4 It is the threshold voltage value of a gallium nitride transistor after being subjected to different drain voltage stresses. According to Figure 2 the test method shown and Figure 3 the standard for extracting the threshold voltage shown. The data shows that for a power gallium nitride transistor with a rated drain voltage of 650V, when its drain voltage stress increases from 0V to 400V, its threshold voltage basically shows the characteristic of first increasing and then flattening. When the gallium nitride transistor's drain bears a voltage stress of 100V, the threshold voltage drift amount is close to 0.7V. The increase in the threshold voltage will cause the transistor to be more "difficult to turn on", that is, when using a fixed drive voltage to drive the gate of the transistor, the on-resistance of the device will increase, reducing the efficiency of the transistor and the circuit system and resulting in more heat generation. To improve the working performance of the transistor, the gate drive voltage of the transistor can be dynamically regulated according to the working state and performance degradation parameters of the transistor in the circuit system.

[0034] Figure 5 It is a schematic diagram of the control circuit principle of the gallium nitride device drive power supply. The power supply includes 4 modules, namely "rectangular wave generation module, filtering module, gate drive module, power module".

[0035] The rectangular wave generation module uses a low-cost 555 chip to generate rectangular waves below 2 MHz in an "analog" manner, including a first-stage 555 chip, resistors R1, R2, R3, diodes D1, D2, capacitors C1, C2. Among them, the common connection point where resistor R1 and R2 are connected is connected to pin 7 of the first-stage 555 chip and the anode of diode D1. The other end of resistor R1 is connected to pin 4, pin 8 of the first-stage 555 chip and V CC is connected. The other end of resistor R2 is connected to the cathode of diode D2. The anode of diode D2 is connected to one end of resistor R3, pin 2 and pin 6 of the first-stage 555 chip. The other end of resistor R3 is connected to the cathode of diode D1. The common connection point where capacitor C1 and C2 are connected is connected to pin 1 of the first-stage 555 chip and grounded. The other end of capacitor C1 is connected to the sliding end of resistor R3. The other end of capacitor C2 is connected to pin 5 of the first-stage 555 chip. Pin 3 of the first-stage 555 chip is connected to the filtering module. The first-stage 555 chip operates in the astable multivibrator mode, and the period and duty cycle of the rectangular wave are controlled by resistors R1, R2, R3 and capacitor C1. Diodes D1, D2 are used to control the charging and discharging paths of capacitor C1, thereby improving the flexibility of adjusting the duty cycle. R1, R2 act as current-limiting resistors to limit the circuit current when the value of variable resistor R3 is small, preventing the first-stage 555 chip from being burned out. Pin 3 of the first-stage 555 chip is the output point, outputting a rectangular wave V1 that meets the requirements. The duration of the high level of the rectangular wave T ON = Ln2 × (R1 + R 3左 ) × C1, the duration of the low level of the rectangular wave T OFF = Ln2 × (R2 + R 3右 ) × C1, the period T = T ON + T OFF = Ln2 × (R1 + R2 + R3) × C1, the frequency f = 1 / T = 1 / [Ln2 × (R1 + R2 + R3) × C1], the duty cycle D = T ON / (T ON + T OFF ) = (R1 + R 3左 ) / (R1 + R2 + R3). Since the duty cycle D is only related to resistors R1, R2, R3, and the frequency of the rectangular wave is related to resistors R1, R2, R3 and capacitor C1. Therefore, the parameters of resistors R1, R2, R3 can be determined first according to the duty cycle, and then the parameter of capacitor C1 can be determined according to the target frequency of the rectangular wave.

[0036] The filtering module is an RLC second-order low-pass filter, which includes resistors R4 and R5, inductor L1, capacitor C3, and an operational amplifier. One end of inductor L1 is connected to one end of resistor R4, and the other end of inductor L1 is connected to one end of capacitor C3, resistor R5, and the non-inverting input terminal of the operational amplifier. The other ends of capacitor C3 and resistor R5 are connected and grounded. The inverting input terminal and the output terminal of the operational amplifier are connected to the gate drive module, and the other end of resistor R4 is connected to pin 3 of the first-stage 555 chip. In the present invention, the filtering module essentially belongs to an LC filtering circuit, and resistor R4 can be used to control the current spike of this module. When specifically applied, appropriate parameters of resistor R4, R5, inductor L1, and capacitor C3 should be selected according to experimental needs. This filtering module first converts the rectangular wave signal into direct current, and then, by means of the voltage follower function of the operational amplifier, increases the load-carrying capacity (can output a larger current) on the premise that the voltage value of this direct current remains unchanged.

[0037] The gate drive module includes a second-stage 555 chip, resistors R6, R7, R8, diodes D3 and D4, capacitors C4 and C5. Among them, the common connection point of resistors R6 and R7 is connected to pin 7 of the second-stage 555 chip and the anode of diode D3. The other end of resistor R6 is connected to pins 4 and 8 of the second-stage 555 chip and the output terminal of the operational amplifier of the filtering module. The other end of resistor R7 is connected to the cathode of diode D4. The anode of diode D4 is connected to one end of resistor R8 and pins 2 and 6 of the second-stage 555 chip. The other end of resistor R8 is connected to the cathode of diode D3. The common connection point of capacitors C4 and C5 is connected to pin 1 of the second-stage 555 chip and grounded. The other end of capacitor C4 is connected to the sliding end of resistor R8, and the other end of capacitor C5 is connected to pin 5 of the second-stage 555 chip. The drive chip is connected to the second-stage 555 chip and the power module. In the present invention, the direct current generated by the filtering module is used as the power supply for the second-stage 555 chip and the gate drive chip. The second-stage 555 chip is used to generate a pulse signal, and the gate drive chip is used to convert the pulse signal into a pulse voltage "with load-carrying capacity" and use this pulse voltage as the gate drive voltage of the transistor. The second-stage 555 chip can be set to work in "astable mode, monostable mode, flip-flop mode", etc. according to experimental needs. When the second-stage 555 chip works in the astable oscillation mode, resistors R6, R7, R8, and capacitor C4 are used to control the period and duty cycle of the rectangular wave. Diodes D3 and D4 are used to control the charging and discharging paths of capacitor C4, which can improve the flexibility of adjusting the duty cycle. V3 is used as the output point to output a rectangular wave that meets the design requirements.

[0038] The power module represents the "power circuit" when the gallium nitride transistor is actually working. The power module includes a resistor R9 and the device under test, the gallium nitride transistor. The resistor R9 is connected to the drain of the gallium nitride transistor, and the source and gate of the gallium nitride transistor are connected to the drive chip. Figure 5 A simple inverter circuit is used as the application scenario. Simulation verification shows that when the rectangular wave generation module works to output a 100 kHz rectangular wave, the filtering module can filter the rectangular wave to generate direct current with a low voltage ripple (within 0.05 V) within 0.1 s. When the working frequency of the rectangular wave is further increased, the ripple of the direct current of the filtering module can be reduced, and the values of the inductor and capacitor of the filtering module can be further reduced. However, high-frequency rectangular waves will introduce greater "electromagnetic interference (EMI)", and the frequency of the output rectangular wave can be flexibly designed according to actual needs.

[0039] Figure 6 It is a flow chart of the method for regulating the driving power supply of gallium nitride devices. The first step is to determine the target gate driving voltage of the gallium nitride transistor. First, determine the actual working state of the transistor (such as the drain voltage stress suffered by the transistor), and then determine the threshold voltage drift of the gallium nitride device based on the device manual or the actual test of the device's dynamic transfer curve. Furthermore, determine the amount of gate driving voltage to be compensated and the target driving voltage according to the threshold voltage drift. The second step is to generate an adjustable and loadable DC voltage required for driving. First, set the resistance and capacitance values of the "rectangular wave generation module" to adjust the duty cycle and frequency of the rectangular wave. Then, set the resistance, inductor, and capacitance values of the "filtering module" to filter the rectangular wave into direct current, and use the voltage follower function of the operational amplifier to convert this direct current into a loadable (able to output a certain current) direct current, and use this direct current to supply power to the second-stage 555 chip and the drive chip. The third step is to output various pulse waveforms that meet the requirements and connect them to the gate of the device under test, the gallium nitride transistor, as driving signals. First, use the second-stage 555 chip to set the chip working mode (such as multivibrator, monostable, etc.), and determine the resistance and capacitance values of the gate driving module, so as to obtain various pulse control signals. Then, make this pulse control signal pass through the drive chip to amplify the current, and finally obtain a drive power supply with an adjustable gate voltage and use this power supply to drive the transistor gate.

[0040] Embodiment

[0041] Figure 7 is a reference circuit when driving the transistor with a 6V gate voltage. The selected components and their numerical parameters are already in Figure 7The markings are not elaborated here. The voltages at 8 key nodes are marked in the figure. The first - stage 555 chip operates in the astable multivibrator mode. V1 measures the voltage across the capacitor, and V2 measures its output voltage. V3 represents the signal after the filtering module passes through the current - limiting resistor, and V4 represents the voltage signal after passing through the inductor and capacitor of the filtering module. V5 represents the voltage output after the operational amplifier follows V4. This voltage is output by the operational amplifier and has a certain load - driving and output - current capacity. V6 is the voltage across the capacitor of the second - stage 555 chip. In this example, the second - stage 555 chip operates in the astable multivibrator mode and outputs a rectangular wave at pin 3. This rectangular - wave signal becomes a pulse voltage V7 with "load - driving ability (able to output a relatively large current)" after passing through the "driver chip". Connect V7 to the gate of the gallium nitride transistor in the subsequent inverter circuit. The drain of the gallium nitride transistor is connected in series with a 1kΩ resistor to the high - voltage power supply, and V8 represents the drain voltage of the gallium nitride transistor.

[0042] Figure 8 It is simulated using Cadence software Figure 7 The waveforms of the key nodes of the circuit at 60ms steady state. It shows Figure 7 The voltages at the 8 key nodes marked in the circuit. For the 555 chip operating in the astable multivibrator mode, the capacitor voltage fluctuates between 1 / 3 and 2 / 3 of the supply voltage. Since the supply voltage of the first - stage 555 chip is 9V, the voltage V1 across the capacitor of the first - stage 555 chip is an "exponential wave" of 3 - 6V. V2 is at a high level during the increasing stage of V1 and at a low level during the decreasing stage of V1. V3 is the waveform of the rectangular - wave signal after passing through the current - limiting resistor but before passing through the inductor and capacitor. V4 is the signal of the rectangular - wave signal after passing through the filtering module. It can be seen Figure 8 that the ripple of the filtered DC voltage V4 is within 0.05V. The operational amplifier operates in the voltage - follower mode and outputs voltage V5 following voltage V4. Voltage V5 has a certain output - current and load - driving capacity. Voltage V5 supplies power to the subsequent 555 chip and indirectly determines the high level of the rectangular wave output by the subsequent 555 chip. Although the 555 chip is not of the "rail - to - rail" type, the voltage difference between the supply voltage and the high level of the output voltage is a fixed value. Therefore, the required supply voltage of the 555 chip can be deduced from the target high level of the output voltage. The second - stage 555 chip serves as a gate - driver chip, and the operating mode of the 555 chip can be selected according to experimental needs. Figure 7 In the example circuit, the second - stage 555 chip also operates in the astable multivibrator mode, and V6 is the voltage across the capacitor. V7 is the rectangular - wave signal output by the second - stage 555 chip. The drain of the gallium nitride transistor is connected to the high - voltage power supply after connecting a resistor, forming an inverter circuit to verify whether the proposed drive power supply can normally drive the gate of the gallium nitride transistor. V8 is the drain voltage of the gallium nitride transistor.

[0043] The present invention relates to a driving power supply regulation circuit and method for a gallium nitride device, which can achieve low-cost and high-precision driving voltage regulation based on an analog circuit. Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control circuit for a driving power supply of a gallium nitride device, characterized in that: The circuit includes four modules, namely a rectangular wave generation module, a filtering module, a gate drive module, and a power module. The rectangular wave generation module uses a first-stage 555 chip to generate a rectangular wave below 2 MHz. The filtering module converts the rectangular wave into direct current and combines an operational amplifier to increase the output current while keeping the voltage value of the direct current unchanged. The gate drive module uses the direct current generated by the filtering module as the power supply, and adjusts the duty cycle and switching frequency of the gate drive signal of the gallium nitride transistor by adjusting the resistance and capacitance values provided in the gate drive module. The power module is a power application circuit including a gallium nitride transistor, and the gate drive signal of the gallium nitride transistor is adjusted by the gate drive module.

2. The gallium nitride device driving power supply regulation circuit according to claim 1, wherein: The rectangular wave generation module includes a first-stage 555 chip, resistors R1, R2, R3, diodes D1, D2, capacitors C1, C2. Among them, the common connection point where resistor R1 and R2 are connected is connected to the 7th pin of the first-stage 555 chip and the anode of diode D1. The other end of resistor R1 is connected to the 4th pin, 8th pin of the first-stage 555 chip and V CC is connected. The other end of resistor R2 is connected to the cathode of diode D2. The anode of diode D2 is connected to one end of resistor R3, the 2nd pin and 6th pin of the first-stage 555 chip. The other end of resistor R3 is connected to the cathode of diode D1. The common connection point where capacitor C1 and C2 are connected is connected to the 1st pin of the first-stage 555 chip and grounded. The other end of capacitor C1 is connected to the sliding end of resistor R3. The other end of capacitor C2 is connected to the 5th pin of the first-stage 555 chip. The 3rd pin of the first-stage 555 chip is connected to the filtering module.

3. The gallium nitride device driving power supply regulation circuit according to claim 2, characterized in that: The rectangular wave generation module uses a first-stage 555 chip operating in the astable oscillation mode to output a rectangular wave, and uses resistors R1, R2, R3 and capacitor C1 to control the period and duty cycle of the rectangular wave, and improves the flexibility of duty cycle adjustment through diodes D1 and D2.

4. The gallium nitride device driving power supply regulation circuit according to claim 1, characterized in that: The filtering module includes resistors R4, R5, inductor L1, capacitor C3 and an operational amplifier. One end of inductor L1 is connected to one end of resistor R4, and the other end of inductor L1 is connected to one end of capacitor C3, resistor R5 and the non-inverting input terminal of the operational amplifier. The other ends of capacitor C3 and resistor R5 are connected and grounded. The inverting input terminal and the output terminal of the operational amplifier are connected to the gate drive module, and the other end of resistor R4 is connected to pin 3 of the first-stage 555 chip.

5. The gallium nitride device driving power supply regulation circuit according to claim 1, wherein: The gate drive module includes a second-stage 555 chip, resistors R6, R7, R8, diodes D3, D4, capacitors C4, C5. The common connection point of resistors R6 and R7 is connected to pin 7 of the second-stage 555 chip and the anode of diode D3. The other end of resistor R6 is connected to pins 4 and 8 of the second-stage 555 chip and the output terminal of the operational amplifier of the filtering module. The other end of resistor R7 is connected to the cathode of diode D4. The anode of diode D4 is connected to one end of resistor R8 and pins 2 and 6 of the second-stage 555 chip. The other end of resistor R8 is connected to the cathode of diode D3. The common connection point of capacitors C4 and C5 is connected to pin 1 of the second-stage 555 chip and grounded. The other end of capacitor C4 is connected to the sliding end of resistor R8. The other end of capacitor C5 is connected to pin 5 of the second-stage 555 chip. The drive chip is connected to the second-stage 555 chip and the power module.

6. The gallium nitride device driving power supply regulation circuit according to claim 5, wherein: The gate drive module uses the direct current output by the filtering module as the power supply, and uses the second-stage 555 chip of this module to generate the control signal required by the gate drive chip. According to the experimental needs, the second-stage 555 chip is set to operate in the astable oscillation mode, monostable mode or flip-flop mode. When the second-stage 555 chip operates in the astable oscillation mode, resistors R6, R7, R8 and capacitor C4 are used to control the period and duty cycle of the drive waveform, and output a drive waveform that meets the design requirements. The gate drive chip is used to amplify the output current capacity of the drive waveform to control the turn-on and turn-off of the subsequent gallium nitride transistor.

7. The gallium nitride device driving power supply regulation circuit according to claim 1, wherein: The power module includes a resistor R9 and a gallium nitride transistor to be measured. The resistor R9 is connected to the drain of the gallium nitride transistor, and the source and gate of the gallium nitride transistor are connected to the drive chip.

8. A method for regulating a driving power supply of a gallium nitride device, characterized in that, It is realized by the gallium nitride device drive power supply regulation circuit according to any one of claims 1-7, and includes the following steps: In the first step, determine the optimal gate drive voltage of the gallium nitride transistor. First, determine the actual working state of the transistor, and then obtain the threshold voltage drift of the gallium nitride device based on the device manual or the actual test of the device's dynamic transfer curve. Furthermore, adjust the gate drive voltage according to the threshold voltage drift. In the second step, generate the required direct current for driving. First, set the resistance and capacitance values of the rectangular wave generation module to adjust the duty cycle and frequency of the rectangular wave. Then, set the resistance, inductance, and capacitance values of the filter module to convert the rectangular wave into direct current, and use the voltage follower function of the operational amplifier to convert this direct current into a load-carrying direct current, and use this direct current to supply power to the second-stage 555 chip and the drive chip. In the third step, output various types of pulse waveforms that meet the requirements and connect them to the gate of the gallium nitride transistor to be measured as drive signals. Use the second-stage 555 chip to set the working mode of the chip, and determine the resistance and capacitance values of the gate drive module, so as to obtain various types of pulse signals to control the gate drive chip.

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