Control device and switching power supply based on GaN power transistor

Abstract

This invention provides a control device and switching power supply based on GaN power transistors. The GaN-based control device includes: a logic control module, a drive module, a MOSFET, a GaN power transistor, and a drive regulation module. The logic control module generates a logic control signal based on a feedback signal received from the feedback terminal of the control device and a sampling signal received from the sampling terminal of the control device. The drive module generates a drive signal based on the logic control signal. The MOSFET responds to the drive signal by turning on or off. The GaN power transistor responds to the on / off state of the MOSFET and is turned on or off under the control of the drive regulation module.

Description

[Technical Field]

[0001] This invention relates to the field of switching power supply technology, and more specifically, to a control device and switching power supply based on GaN power transistors. [Previous Technology]

[0002] GaN is suitable for higher switching frequencies, reduces switching losses compared to traditional metal-oxide-semiconductor field-effect transistors (MOSFETs), and has low drain-source on-resistance (Rdson). Its application in switching power supplies can significantly improve system efficiency, hence the rapid increase in GaN usage in recent years. Enhancement-mode GaN (E-mode GaN) is relatively simple to drive and is more suitable for low-to-medium power applications, while depletion-mode GaN (D-mode GaN) requires a MOSFET but offers higher reliability and is more suitable for medium-to-high power applications. [Summary of the Invention]

[0003] In one aspect, an embodiment of the present invention provides a control device based on a GaN power transistor, comprising: a logic control module, a drive module, a metal-oxide-semiconductor field-effect transistor (MOSFET), a GaN power transistor, and a drive adjustment module. The logic control module generates a logic control signal based on a feedback signal received at a feedback terminal of the control device and a sampling signal received at a sampling terminal of the control device. The drive module generates a drive signal based on the logic control signal. The MOSFET responds to the drive signal by turning on or off. The GaN power transistor responds to the MOSFET's on or off state and is turned on or off under the control of the drive adjustment module.

[0004] In one aspect, an embodiment of the present invention provides a switching power supply including a control device provided according to an embodiment of the present invention.

[0005] The GaN-based control device and switching power supply provided according to the embodiments of the present invention can adjust the switching speed of the GaN power transistor by adding a drive adjustment module to the gate terminal of the GaN power transistor, thereby optimizing the system electromagnetic interference (EMI). [Simplified Explanation of the Diagram]

[0006] To make the objectives, solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. The various aspects of the present invention can be best understood by reading the following detailed description in conjunction with the drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Note that, according to industry standard practice, various features are not necessarily drawn to scale. In the various figures, similar numerical labels describe similar elements. In the drawings:

[0006] Figure 1 shows the I / V characteristic curves of D-mode GaN;

[0006] Figure 2 shows a circuit diagram of a conventional control device based on GaN power transistors;

[0006] Figure 3 shows a waveform diagram of a conventional control device based on GaN power transistors;

[0006] Figure 4 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention;

[0006] Figure 5 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention;

[0006] Figure 6 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention;

[0006] Figure 7 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention;

[0006] Figure 8 shows a circuit diagram of an adjustable resistance branch according to an embodiment of the present invention.

[0006] Figure 9 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention;

[0006] Figure 10 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention; and

[0006] Figure 11 shows a schematic diagram of a switching power supply including a control device based on a GaN power transistor according to an embodiment of the present invention.

Implementation Method

[0007] Features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific configurations and algorithms presented below, but covers any modifications, substitutions, and improvements to elements, components, and algorithms without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description in order to avoid unnecessarily obscuring the invention.

[0008] Figure 1 shows the I / V characteristic curves of D-mode GaN. The I / V characteristics of D-mode GaN are similar to those of junction field-effect transistors (JFETs) and depletion-mode MOSFETs. When D-mode GaN is used in switching power supplies, a low-voltage MOSFET needs to be connected in series at its lower end for switching control. The Rdson of the low-voltage MOSFET is typically about 1 / 10 of that of the D-mode GaN.

[0009] Figure 2 shows a circuit diagram of a conventional GaN power transistor-based control device. As shown in Figure 2, the conventional GaN power transistor-based control device 200 includes: a logic control module 201, a drive module 202, a metal-oxide-semiconductor field-effect transistor (MOSFET) M2, and a GaN power transistor M1. The logic control module 201 generates a logic control signal based on the feedback signal received at the feedback terminal FB of the control device 200 and the sampling signal received at the sampling terminal CS of the control device 200; the drive module 202 generates a drive signal based on the logic control signal; the MOSFET M2 turns on or off in response to the drive signal; and the GaN power transistor M1 turns on or off in response to the on or off state of the MOSFET M2.

[0010] In addition, as shown in Figure 2, the conventional GaN power transistor-based control device 200 also includes a power supply module 203. The power supply module 203 provides power supply voltage, voltage and current bias, etc., for other modules (e.g., logic control module 201, drive module 202). The control device 200 shown in Figure 2 can be applied to a switching power supply. As shown in Figure 2, when applied to a switching power supply, the power supply terminal (pin) Vcc of the control device 200 is connected to the input module of the switching power supply and grounded via the first capacitor C1; the feedback terminal FB of the control device 200 is connected to the output feedback of the switching power supply; the sampling terminal CS of the control device 200 is grounded via the sampling resistor Rsense; and the drain terminal of the GaN power transistor M1 of the control device 200 is connected to the output module of the switching power supply (e.g., the primary winding Lp of the transformer in the output module) as the output terminal Drain of the control device.

[0011] As shown in Figure 2, the main working principle of the conventional GaN power transistor-based control device 200 is as follows: The GaN power transistor M1 is indirectly controlled by directly controlling the gate voltage Gate2 of MOSFET M2 via a drive signal. Specifically, when the gate voltage Gate2 of MOSFET M2 is at a high level, MOSFET M2 is turned on, the source voltage Vds2 of GaN power transistor M1 decreases, and GaN power transistor M1 is turned on. When the gate voltage Gate2 of MOSFET M2 is at a low level, MOSFET M2 is turned off, and the source voltage Vds2 of GaN power transistor M1 increases, causing GaN power transistor M1 to be pinched off.

[0012] Since the gate of GaN power transistor M1 is directly connected to the source of MOSFET M2 at its lower end, i.e., the sampling terminal CS, and the source of GaN power transistor M1 is cascaded to the drain of MOSFET M2, the gate-source voltage of GaN power transistor M1 is only controlled by the switching of MOSFET M2. That is, the switching speed of GaN power transistor M1 is only controlled by the switching speed of MOSFET M2. Therefore, it is difficult to regulate the electromagnetic interference (EMI) of the system. Moreover, at the moment when MOSFET M2 is turned off, the source voltage Vds2 of GaN power transistor M1 rises instantaneously, which may exceed the gate-source voltage withstand voltage of GaN power transistor M1, thereby reducing reliability.

[0013] Figure 3 shows a waveform diagram of the conventional GaN power transistor-based control device shown in Figure 2. In Figure 3, Vds represents the source-drain voltage of MOSFET M2, which is also the source voltage of GaN power transistor M1. Gate2 represents the gate voltage of MOSFET M2, and Ip represents the current flowing through GaN power transistor M1. As shown in Figure 3, when the gate voltage Gate2 of MOSFET M2 is at a high level, MOSFET M2 is turned on, the source voltage Vds2 of GaN power transistor M1 decreases, GaN power transistor M1 is turned on, and the current Ip flowing through GaN power transistor M1 gradually increases. When the gate voltage Gate2 of MOSFET M2 is at a low level, MOSFET M2 is turned off, the source voltage Vds2 of GaN power transistor M1 increases, causing GaN power transistor M1 to be pinched off, and the current Ip flowing through GaN power transistor M1 becomes zero. It can be seen that the switching speed of GaN power transistor M1 is only controlled by the switching speed of its lower MOSFET M2. As mentioned above, this makes it difficult to regulate the system's electromagnetic interference (EMI) and reduces its reliability.

[0014] In view of the above, the present invention provides a control device and switching power supply based on GaN power transistor, so that the switching speed of GaN power transistor is no longer controlled only by the switching speed of its lower MOSFET M2, but is adjustable.

[0015] Figure 4 shows a circuit diagram of a control device based on GaN power transistor according to an embodiment of the present invention.

[0016] As shown in FIG4, the control device 400 based on GaN power transistor according to an embodiment of the present invention includes: a logic control module 401, a drive module 402, a metal-oxide-semiconductor field-effect transistor MOSFET M1, a GaN power transistor M1, and a drive adjustment module 403, wherein the logic control module 401 generates a logic control signal based on the feedback signal received by the feedback terminal FB of the control device 400 and the sampling signal received by the sampling terminal CS of the control device 400; the drive module 402 generates a drive signal based on the logic control signal; the MOSFET M2 is turned on or off in response to the drive signal; and the GaN power transistor M1 is turned on or off in response to the turn-on or turn-off of the MOSFET M2 and under the control of the drive adjustment module 403.

[0017] In addition, as shown in FIG4, the control device 400 based on GaN power transistor according to an embodiment of the present invention further includes a power supply module 404 and a high voltage start-up module 405.

[0018] The power supply module 404 provides power supply voltage, voltage and current bias, etc., for other modules (such as the logic control module 401 and the high-voltage start-up module 405). In some implementations, the power supply module 404 may include power terminal Vcc start-up control circuit, LDO circuit, basic reference voltage source and current source, etc.

[0019] The high-voltage starting module 405 controls the starting of the control device 400. Specifically, in the initial state of the control device 400, the power supply terminal Vcc of the control device 400 is at a low voltage and the GaN power transistor M1 is in the on state. During the starting process of the control device 400, the input voltage received by the drain terminal Drain of the GaN power transistor M1 charges the power supply capacitor C1 of the control device 400 via the high-voltage starting module 405, the power supply module 404, and then via the power supply terminal Vcc. When the voltage on the power supply terminal Vcc (i.e., the voltage on the power supply capacitor C1) reaches the starting voltage of the control device 400, the control device 400 starts.

[0020] In some implementations, as shown in FIG4, the first input terminal of the logic control module 401 is connected to the feedback terminal FB, and the second input terminal of the logic control module 401 is connected to the sampling terminal CS; the input terminal of the drive module 402 is connected to the output terminal of the logic control module 401; the gate terminal of the MOSFET M2 is connected to the output terminal of the drive module 402, and the source terminal of the MOSFET M2 is connected to the sampling terminal CS; the source terminal of the GaN power transistor M1 is connected to the drain terminal of the MOSFET M2, and the drain terminal of the GaN power transistor M1 serves as the output terminal of the control device 400; and the first terminal of the drive adjustment module 403 is connected to the gate terminal of the GaN power transistor M1, and the second terminal of the drive adjustment module 403 is connected to the source terminal of the MOSFET M2.

[0021] Furthermore, as shown in Figure 4, the first terminal of the power supply module 404 is connected to the power supply terminal Vcc, the second terminal of the power supply module 404 is connected to the logic control module 401, and the third terminal of the power supply module 404 is connected to the first terminal of the high-voltage start-up module 405, and the second terminal of the high-voltage start-up module 405 is connected to the source of the GaN power transistor M1. The control device 400 shown in Figure 4 can be applied to a switching power supply. As shown in Figure 4, when applied to a switching power supply, the power supply terminal Vcc of the control device 400 is connected to the input module of the switching power supply and grounded via the power supply capacitor (first capacitor) C1, the feedback terminal FB of the control device 400 is connected to the output feedback of the switching power supply, the sampling terminal CS of the control device 400 is grounded via the sampling resistor Rsense, and the drain terminal Drain of the GaN power transistor M1 of the control device 400 is connected to the output module of the switching power supply (such as the primary winding Lp of the transformer in the output module) as the output terminal of the control device.

[0022] Compared to the conventional GaN power transistor-based control device shown in Figure 2, the control device according to an embodiment of the present invention adds a drive adjustment module. By adding a drive adjustment module to the gate of the GaN power transistor, the switching speed of the GaN power transistor can be adjusted, thereby optimizing the system electromagnetic interference (EMI).

[0023] Figure 5 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention. The configuration in Figure 5 is the same as that in Figure 4, and the specific structure of the high-voltage start-up module 405 is shown in particular.

[0024] As shown in Figure 5, the high-voltage start-up module 405 includes a first diode D1, a first resistor R1, and a first switch S1 connected in series, wherein the first diode D1 and the first switch S1 are respectively connected to the power supply module 404 and the GaN power transistor M1. Furthermore, the first switch S1 is turned on or off according to a signal from the power supply module 404. Specifically, in the initial state of the control device 400, the power supply terminal Vcc of the control device 400 is at a low voltage, and the first switch S1 is turned on according to a signal from the power supply module 404, thereby enabling the input voltage received by the drain terminal Drain of the GaN power transistor M1 during the start-up process of the control device 400 to charge the power supply capacitor C1 of the control device 400 via the high-voltage start-up module 405, the power supply module 404, and further via the power supply terminal Vcc. When the voltage on the power terminal Vcc (i.e., the voltage on the power supply capacitor C1) reaches the start-up voltage of the control device 400, the control device 400 is started, and at this time the first switch S1 is opened according to the signal from the power module 404.

[0025] Figure 6 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention.

[0026] As shown in FIG6, the control device 600 based on GaN power transistor according to an embodiment of the present invention includes: a logic control module 601, a drive module 602, a metal-oxide-semiconductor field-effect transistor MOSFET M1, a GaN power transistor M1, and a drive adjustment module 603, wherein the logic control module 601 generates a logic control signal based on the feedback signal received by the feedback terminal FB of the control device 600 and the sampling signal received by the sampling terminal CS of the control device 600; the drive module 602 generates a drive signal based on the logic control signal; the MOSFET M2 is turned on or off in response to the drive signal; and the GaN power transistor M1 is turned on or off in response to the turn-on or turn-off of the MOSFET M2 and under the control of the drive adjustment module 603.

[0027] Furthermore, as shown in FIG6, the GaN power transistor-based control device 600 according to an embodiment of the present invention further includes a power supply module 604 and a high-voltage startup module 605. The power supply module 604 provides power supply voltage, voltage and current bias, etc., to other modules (e.g., logic control module 601 and high-voltage startup module 605). The high-voltage startup module 605 controls the startup of the control device 600.

[0028] The connections of the logic control module 601, drive module 602, MOSFET M1, GaN power transistor M1, drive regulation module 603, power supply module 604, and high-voltage start-up module 605 in Figure 6 are the same as those of the logic control module 401, drive module 402, MOSFET M1, GaN power transistor M1, drive regulation module 403, power supply module 404, and high-voltage start-up module 405 in Figure 4, and will not be repeated here. Similarly, the control device 600 shown in Figure 6 can be applied to a switching power supply. The connections of the terminals of the control device 600 are the same as those of the terminals of the control device 400 shown in Figure 4, and will not be repeated here.

[0029] In addition, as shown in FIG6, the drive adjustment module 603 includes: a second resistor R2, a second diode D2 and a third resistor R3, wherein the first end of the second resistor R2 is connected to the gate terminal of the GaN power transistor M1, the second end of the second resistor R2 is connected to the source terminal of the MOSFET M2, the first end of the second diode D2 is connected to the gate terminal of the GaN power transistor M1, the second end of the second diode D2 is connected to the first end of the third resistor R3, and the second end of the third resistor R3 is connected to the source terminal of the MOSFET M2, wherein the second resistor R2 and the third resistor R3 each have a fixed resistance value.

[0030] The drive adjustment circuit 603 includes a second resistor R2 (rising edge resistor), a second diode D2, and a third resistor R3 (falling edge resistor), which can adjust the switching speed of the GaN power transistor M1 at the rising edge of turn-on and the falling edge of pinch-off. Generally, the resistance value of the second resistor R2 is greater than the resistance value of the third resistor R3. The larger the resistance value of the second resistor R2, the slower the turn-on speed of the GaN power transistor M1; conversely, the smaller the resistance value of the second resistor R2, the faster the turn-on speed of the GaN power transistor M1. Similarly, the larger the resistance value of the third resistor R3, the slower the turn-off speed of the GaN power transistor M1; conversely, the smaller the resistance value of the third resistor R3, the faster the turn-off speed of the GaN power transistor M1. By adjusting the resistance values ​​of the rising edge and falling edge resistors, the purpose of optimizing electromagnetic interference (EMI) can be achieved.

[0031] Figure 7 shows a circuit diagram of a control device based on GaN power transistor according to an embodiment of the present invention.

[0032] As shown in FIG7, the control device 700 based on GaN power transistor according to an embodiment of the present invention includes: a logic control module 701, a drive module 702, a metal-oxide-semiconductor field-effect transistor MOSFET M1, a GaN power transistor M1, and a drive adjustment module 703, wherein the logic control module 701 generates a logic control signal based on the feedback signal received by the feedback terminal FB of the control device 700 and the sampling signal received by the sampling terminal CS of the control device 700; the drive module 702 generates a drive signal based on the logic control signal; the MOSFET M2 is turned on or off in response to the drive signal; and the GaN power transistor M1 is turned on or off in response to the turn-on or turn-off of the MOSFET M2 and under the control of the drive adjustment module 703.

[0033] Furthermore, as shown in FIG7, the GaN power transistor-based control device 700 according to an embodiment of the present invention further includes a power supply module 704 and a high-voltage start-up module 705. The power supply module 704 provides power supply voltage, voltage and current bias, etc., to other modules (e.g., logic control module 701 and high-voltage start-up module 705). The high-voltage start-up module 705 controls the start-up of the control device 700.

[0034] The connections of the logic control module 701, drive module 702, MOSFET M1, GaN power transistor M1, drive regulation module 703, power supply module 704, and high-voltage start-up module 705 in Figure 7 are the same as those of the logic control module 401, drive module 402, MOSFET M1, GaN power transistor M1, drive regulation module 403, power supply module 404, and high-voltage start-up module 405 in Figure 4, and will not be repeated here. Similarly, the control device 700 shown in Figure 7 can be applied to a switching power supply. The connections of the terminals of the control device 700 are the same as those of the terminals of the control device 400 shown in Figure 4, and will not be repeated here.

[0035] Additionally, as shown in Figure 7, the drive adjustment module 703 includes: a first adjustable resistance branch 703-1, a second diode D2, and a second adjustable resistance branch 703-2. The first terminal of the first adjustable resistance branch 703-1 is connected to the gate terminal of the GaN power transistor M1, and the second terminal of the first adjustable resistance branch 703-1 is connected to the source terminal of the MOSFET M2. The first terminal of the second diode D2 is connected to the gate terminal of the GaN power transistor M1, and the second terminal of the first diode D1 is connected to the first terminal of the second adjustable resistance branch 703-2. The second terminal of the second adjustable resistance branch 703-2 is also connected to the MOSFET. The source terminal of M2, wherein the first adjustable resistance branch 703-1 responds to the first switch control signal Sr[1:n] from the logic control module 701 to adjust the first adjustable resistance of the first adjustable resistance branch 703-1, and the second adjustable resistance branch 703-2 responds to the second switch control signal Sf[1:n] from the logic control module 701 to adjust the second adjustable resistance of the second adjustable resistance branch 703-2. Figure 8 shows a circuit diagram of the adjustable resistance branch according to an embodiment of the present invention. As shown in Figure 8, the first adjustable resistance branch 703-1 includes: at least two fourth resistors Rr[1:n] connected in series and a switch S[1:n] connected in parallel with each of the at least two fourth resistors Rr[1:n], wherein the switch S[1:n] connected in parallel with each of the at least two fourth resistors Rr[1:n] is independently controlled to be turned on or off in response to the first switch control signal Sr[1:n] from the logic control module 701; and the second adjustable resistance branch 703-2 includes: at least two fifth resistors Rf[1:n] connected in series and a switch W[1:n] connected in parallel with each of the at least two fifth resistors Rf[1:n], wherein the switch W[1:n] connected in parallel with each of the at least two fifth resistors Rf[1:n] is independently controlled to be turned on or off in response to the second switch control signal Sf[1:n] from the logic control module 701. It should be understood that at least two fourth resistors Rr[1:n] may be the same or different; at least two fifth resistors Rf[1:n] may be the same or different. The resistance in the fourth resistors Rr[1:n] may be the same or different from the resistance in the fifth resistors Rf[1:n].

[0036] More specifically, as shown in Figure 8, the switches S[1:n] of the first adjustable resistor branch 703-1 are controlled by the first switch control signal Sr[1:n], which allows the resistance value of the first adjustable resistor branch 703-1 to be adjusted from 0 to Rr1+Rr2+...Rrn, thereby enabling precise adjustment of the rising edge turn-on speed. Similarly, as shown in Figure 8, the switches W[1:n] of the second adjustable resistor branch 703-2 are controlled by the second switch control signal Sf[1:n], which allows the resistance value of the second adjustable resistor branch 703-2 to be adjusted from 0 to Rf1+Rf2+...Rfn, thereby enabling precise adjustment of the falling edge turn-off speed. In this way, the purpose of optimizing EMI for control devices and switching power supplies based on GaN power transistors with different Rdson can be achieved.

[0037] Each of the switch S[1:n] of the first adjustable resistance branch 703-1 and the switch W[1:n] of the second adjustable resistance branch 703-2 can be any circuit switch, including but not limited to semiconductor control switches, such as MOS transistors and bipolar junction transistors.

[0038] According to the above embodiment, by adding a first adjustable resistor branch 703-1 and a second adjustable resistor branch 703-2 to receive the first switch control signal Sr[1:n] and the second switch control signal Sf[1:n] provided by the logic control module 701, the resistance values ​​of the first adjustable resistor branch 703-1 and the second adjustable resistor branch 703-2 can be adjusted respectively. In this way, when using GaN power transistors M1 with different Rdson values, the switching speed of the GaN power transistor M1's rising edge and falling edge can be adjusted by adjusting the resistance values ​​of the first adjustable resistor branch 703-1 and the second adjustable resistor branch 703-2, so as to optimize EMI and make the design more flexible.

[0039] Figure 9 shows a circuit diagram of a control device based on a GaN power transistor according to an embodiment of the present invention.

[0040] As shown in FIG9, the control device 900 based on GaN power transistor according to an embodiment of the present invention includes: a logic control module 901, a drive module 902, a metal-oxide-semiconductor field-effect transistor MOSFET M1, a GaN power transistor M1, and a drive adjustment module 903, wherein the logic control module 901 generates a logic control signal based on the feedback signal received by the feedback terminal FB of the control device 900 and the sampling signal received by the sampling terminal CS of the control device 900; the drive module 902 generates a drive signal based on the logic control signal; the MOSFET M2 is turned on or off in response to the drive signal; and the GaN power transistor M1 is turned on or off in response to the on or off of the MOSFET M2 and is turned on or off under the control of the drive adjustment module 903.

[0041] Furthermore, as shown in FIG9, the GaN power transistor-based control device 900 according to an embodiment of the present invention further includes a power supply module 904 and a high-voltage start-up module 905. The power supply module 904 provides power supply voltage, voltage and current bias, etc., to other modules (e.g., logic control module 901 and high-voltage start-up module 905). The high-voltage start-up module 905 controls the start-up of the control device 900.

[0042] The connections of the logic control module 901, drive module 902, MOSFET M1, GaN power transistor M1, drive regulation module 903, power supply module 904, and high-voltage start-up module 905 in Figure 9 are the same as those of the logic control module 401, drive module 402, MOSFET M1, GaN power transistor M1, drive regulation module 403, power supply module 404, and high-voltage start-up module 405 in Figure 4, and will not be repeated here. Similarly, the control device 900 shown in Figure 9 can be applied to a switching power supply. The connections of the terminals of the control device 900 are the same as those of the terminals of the control device 400 shown in Figure 4, and will not be repeated here.

[0043] Additionally, as shown in FIG9, the control device 900 according to an embodiment of the present invention further includes a voltage clamping module 906, configured to clamp the voltage at the source terminal of the GaN power transistor M1 to a clamping voltage at the instant the GaN power transistor M1 is turned off. As shown in FIG9, the voltage clamping module 906 is connected to the source terminal of the GaN power transistor M1.

[0044] Figure 10 shows a circuit diagram of a control device based on GaN power transistor according to an embodiment of the present invention.

[0045] As shown in FIG10, the control device 1000 based on GaN power transistor according to an embodiment of the present invention includes: a logic control module 1001, a drive module 1002, a metal oxide semiconductor field-effect transistor MOSFET M1, a GaN power transistor M1, and a drive adjustment module 1003, wherein the logic control module 1001 generates a logic control signal based on the feedback signal received by the feedback terminal FB of the control device 1000 and the sampling signal received by the sampling terminal CS of the control device 1000; the drive module 1002 generates a drive signal based on the logic control signal; the MOSFET M2 is turned on or off in response to the drive signal; and the GaN power transistor M1 is turned on or off in response to the turn-on or turn-off of the MOSFET M2 and under the control of the drive adjustment module 1003.

[0046] Furthermore, as shown in FIG10, the GaN power transistor-based control device 1000 according to an embodiment of the present invention further includes a power supply module 1004 and a high-voltage startup module 1005. The power supply module 1004 provides power supply voltage, voltage and current bias, etc., to other modules (e.g., logic control module 1001 and high-voltage startup module 1005). The high-voltage startup module 1005 controls the startup of the control device 1000.

[0047] The connections of the logic control module 1001, drive module 1002, MOSFET M1, GaN power transistor M1, drive regulation module 1003, power supply module 1004, and high-voltage start-up module 1005 in Figure 10 are the same as those of the logic control module 901, drive module 902, MOSFET M1, GaN power transistor M1, drive regulation module 903, power supply module 904, and high-voltage start-up module 905 in Figure 9, and will not be repeated here. Similarly, the control device 1000 shown in Figure 10 can be applied to a switching power supply. The connections of the terminals of the control device 1000 are the same as those of the terminals of the control device 900 shown in Figure 9, and will not be repeated here.

[0048] Additionally, as shown in FIG10, the control device 1000 according to an embodiment of the present invention further includes a voltage clamping module 1006, configured to clamp the voltage at the source terminal of the GaN power transistor M1 to a clamping voltage at the moment of turn-off. As shown in FIG10, the voltage clamping module 1006 is connected to the source terminal of the GaN power transistor M1.

[0049] As shown in Figure 10, the voltage clamping module 1006 includes: a Zener diode D3, a fifth resistor R5, a sixth resistor R6, a seventh current-limiting resistor R7, and a metal-oxide-semiconductor field-effect transistor (MOSFET) M3. The first terminal of the Zener diode D3 is connected to the source terminal of the GaN power transistor M1, the second terminal of the Zener diode D3 is connected to the first terminal of the fifth resistor R5, the second terminal of the fifth resistor R5 is connected to the first terminal of the sixth resistor R6, and the second terminal of the sixth resistor R6 is grounded. The first terminal of the seventh current-limiting resistor R7 is connected to the source terminal of the GaN power transistor M1, the second terminal of the seventh current-limiting resistor R7 is connected to the drain terminal of the MOSFET M3, the gate terminal of the MOSFET M3 is connected to the junction point of the second terminal of the fifth resistor R5 and the first terminal of the sixth resistor R6, and the source terminal of the MOSFET M3 is grounded.

[0050] As shown in Figure 10, the clamping voltage Vclamp can be determined as:

[0050]

[0051] Where Vth_M3 is the turn-on threshold voltage of the metal-oxide-semiconductor field-effect transistor MOSFET M3, and Vzener is the voltage across the Zener diode. When the source voltage Vds2 of the GaN power transistor M1 exceeds the clamping voltage Vclamp, the metal-oxide-semiconductor field-effect transistor MOSFET M3 turns on, clamping the source voltage Vds2 of the GaN power transistor M1 at the clamping voltage Vclamp through the seventh current-limiting resistor R7.

[0052] In the above embodiments described with reference to Figures 9 and 10, by adding a voltage clamping module 906 / 1006 to the source terminal of the GaN power transistor M1, the voltage at the source terminal of the GaN power transistor M1 is prevented from being too high and exceeding the gate-source voltage VGS of the GaN power transistor M1 at the moment of turn-off, which would cause device damage and enhance the reliability of device operation.

[0053] Although the voltage clamping module 906 / 1006 and the drive adjustment module 903 / 1003 coexist in the above description, it should be understood that the voltage clamping module 906 / 1006 may be included while the drive adjustment module 903 / 1003 may be omitted in order to enhance the reliability of the device operation.

[0054] Figure 11 shows a schematic diagram of a switching power supply including a control device based on a GaN power transistor according to an embodiment of the present invention.

[0055] As shown in FIG11, the control device 1100 according to an embodiment of the present invention includes: an input device 1101, a control device 1102 and an output device 1103.

[0056] The control device 1102 can be implemented using any one of the control devices 400, 500, 600, 800, and 900 in the above embodiments.

[0057] In some implementations, as shown in FIG11, the control device 1102 according to an embodiment of the present invention includes: a logic control module 1102-1, a drive module 1102-2, a metal-oxide-semiconductor field-effect transistor MOSFET M1, a GaN power transistor M1, and a drive adjustment module 1102-3, wherein the logic control module 1102-1 generates a logic control signal based on a feedback signal received from the feedback terminal FB of the control device 1100 and a sampling signal received from the sampling terminal CS of the control device 1100; the drive module 1102-2 generates a drive signal based on the logic control signal; the MOSFET M2 is turned on or off in response to the drive signal; and the GaN power transistor M1 is turned on or off in response to the on or off of the MOSFET M2 and is turned on or off under the control of the drive adjustment module 1102-3.

[0058] Furthermore, as shown in FIG11, the control device 1102 according to an embodiment of the present invention further includes a power supply module 1102-4 and a high-voltage start-up module 1102-5. The power supply module 1102-4 provides power supply voltage, voltage and current bias, etc., to other modules (e.g., logic control module 1102-1 and high-voltage start-up module 1102-5). The high-voltage start-up module 905 controls the start-up of the control device 1102.

[0059] The logic control module 1102-1, drive module 1102-2, MOSFET M1, GaN power transistor M1, drive regulation module 1102-3, power supply module 1102-4 and high-voltage start-up module 1102-5 in Figure 11 are connected in the same way as the logic control module 401, drive module 402, MOSFET M1, GaN power transistor M1 and drive regulation module 403, power supply module 404 and high-voltage start-up module 405 in Figure 4, and will not be described again here.

[0060] Additionally, as shown in FIG11, the control device 1102 according to an embodiment of the present invention further includes a voltage clamping module 1102-6, configured to clamp the voltage at the source terminal of the GaN power transistor M1 to a clamping voltage at the instant the GaN power transistor M1 is turned off. As shown in FIG11, the voltage clamping module 1102-6 is connected to the source terminal of the GaN power transistor M1.

[0061] In some implementations, the logic control module 1102-1 includes: an eighth resistor R8, a ninth resistor R9, a comparator Comp, and an SR flip-flop. The first end of the eighth resistor R8 is connected to the feedback terminal FB, the second end of the eighth resistor R8 is connected to the first end of the ninth resistor R9, and the second end of the ninth resistor R9 is grounded. The positive input terminal of the comparator Comp is connected to the connection point between the second end of the eighth resistor R8 and the first end of the ninth resistor R9, the negative input terminal of the comparator Comp is connected to the sampling terminal FB, and the first input terminal of the SR flip-flop receives the oscillation signal generated by the oscillator OSC. The second input terminal of the SR flip-flop is connected to the output terminal of the comparator Comp, and the output terminal of the SR flip-flop is connected to the drive module 1102-2.

[0062] In some implementations, the driving module 1102-2 includes: a driving circuit based on a MOS transistor, such as a totem pole driving circuit.

[0063] As shown in Figure 11, the input device 1101 includes: an AC source AC, a rectifier circuit DR, a first capacitor C1, a second capacitor C2, a tenth resistor R10, a transformer T1, and a fourth diode D4. The input terminal of the rectifier circuit DR is connected to the AC source AC to receive AC input Vin. The first terminal of the second capacitor C2 is connected to the output terminal of the rectifier circuit DR, and the second terminal of the second capacitor C2 is grounded. The first terminal of the tenth resistor R10 is connected to the output terminal of the rectifier circuit DR, and the second terminal of the tenth resistor R10 is connected to the first terminal of the first capacitor C1, which is grounded. The first terminal of the secondary winding of the transformer T1 is connected via the fourth diode D4 to the junction point of the second terminal of the tenth resistor R10 and the first terminal of the first capacitor C1, and the second terminal of the secondary winding of the transformer T1 is grounded. The junction point of the second terminal of the tenth resistor R10 and the first terminal of the first capacitor C1 is connected to the power supply terminal Vcc of the control device 1102 to provide power voltage to the control device 1102.

[0064] As shown in Figure 11, the output device 1103 includes a second transformer T2, a fifth diode D5, a third capacitor C3, and a feedback & isolation circuit module F&I. The first terminal of the primary side of the second transformer T2 is connected to the output terminal of the rectifier circuit DR in the input device 1101. The second terminal of the primary side of the second transformer T2 is connected to the output terminal of the control device 1102, i.e., the drain terminal Drain of the GaN power transistor M1. The first terminal of the secondary side of the second transformer T2 is connected to the first terminal of the fifth diode D5. The second terminal of the secondary side of the second transformer T2 is grounded. The second terminal of the fifth diode D5 is grounded via the third capacitor C3 and connected to the input terminal of the feedback & isolation circuit module F&I. The output terminal of the feedback & isolation circuit module F&I is connected to the feedback terminal FB of the control device 1102 to provide output feedback. A sampling resistor Rsense is connected between the sampling terminal CS of the control device 1102 and ground.

[0065] According to an embodiment of the present invention, by adding a drive adjustment module 1102-3 to the gate terminal of the GaN power transistor M1, the switching speed of the GaN power transistor can be adjusted, thereby optimizing the system electromagnetic interference (EMI). By adding a voltage clamping module 1102-6 to the source terminal of the GaN power transistor M1, the voltage at the source terminal of the GaN power transistor M1 is prevented from exceeding the gate-source voltage VGS of the GaN power transistor M1 at the moment of turn-off, thus avoiding device damage and enhancing the reliability of device operation. In addition, by adding a high-voltage startup module 1102-5, the system standby power consumption can be reduced.

[0066] It should be understood that the GaN power transistor according to the embodiments of the present invention can be a depletion-mode GaN power transistor. It should also be understood that the above description is based on a flyback architecture switching power supply; however, the embodiments of the present invention can also be applied to power supply architectures such as Buck architecture, Boost architecture, Buck-boost architecture, LLC architecture, and Asymmetric Half Bridge (AHB) architecture.

[0067] The mechanism of the present invention has been described above with reference to the drawings and various embodiments. It should be understood that the present invention is not limited thereto, but may be implemented in other forms without departing from the spirit and essential characteristics of the invention. The present embodiments are to be regarded as exemplary and not limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning of the claims and their equivalents are included within the scope of the invention.

Claims

1. A control device based on GaN power transistors, comprising: The system includes a logic control module, a drive module, a MOSFET, a GaN power transistor, and a drive adjustment module. The logic control module generates a logic control signal based on a feedback signal received from a feedback terminal of the control device and a sampling signal received from a sampling terminal of the control device. The drive module generates a drive signal based on the logic control signal. The MOSFET responds to the drive signal by turning on or off. The GaN power transistor responds to the MOSFET's on or off state and is turned on or off under the control of the drive adjustment module.

2. The control device as described in claim 1 further includes a power supply module and a high-voltage start-up module, wherein the power supply module provides power supply voltage to the high-voltage start-up module and the logic control module, and the start-up control module controls the power-on start-up of the control device.

3. The control device as claimed in claim 2, wherein, The first end of the power module is connected to the power supply terminal of the control device, the second end of the power module is connected to the logic control module, the third end of the power module is connected to the first end of the high-voltage start-up module, and the second end of the high-voltage start-up module is connected to the source terminal of the GaN power transistor.

4. The control device as claimed in claim 3, wherein, The high-voltage starting module includes a first diode, a first resistor, and a first switch connected in series, wherein the first diode and the first switch are respectively connected to the power supply terminal of the control device and the source terminal of the GaN power transistor, and the first switch is turned on or off according to the power supply voltage from the power supply module.

5. The control device as claimed in claim 1, wherein, The first input terminal of the logic control module is connected to the feedback terminal, and the second input terminal of the logic control module is connected to the sampling terminal; the input terminal of the drive module is connected to the output terminal of the logic control module; the gate terminal of the MOSFET is connected to the output terminal of the drive module, and the source terminal of the MOSFET is connected to the sampling terminal; the source terminal of the GaN power transistor is connected to the drain terminal of the MOSFET, and the drain terminal of the GaN power transistor serves as the output terminal of the control device; and the first terminal of the drive adjustment module is connected to the gate terminal of the GaN power transistor, and the second terminal of the drive adjustment module is connected to the source terminal of the MOSFET.

6. The control device as claimed in claim 5, wherein, The drive adjustment module includes a second resistor, a second diode, and a third resistor. The first end of the second resistor is connected to the gate terminal of the GaN power transistor, the second end of the second resistor is connected to the source terminal of the MOSFET, the first end of the second diode is connected to the gate terminal of the GaN power transistor, the second end of the second diode is connected to the first end of the third resistor, and the second end of the third resistor is connected to the source terminal of the MOSFET. The second resistor and the third resistor each have a fixed resistance value.

7. The control device as claimed in claim 5, wherein, The drive adjustment module includes: a first adjustable resistance branch, a second diode, and a second adjustable resistance branch. A first terminal of the first adjustable resistance branch is connected to the gate terminal of the GaN power transistor, and a second terminal of the first adjustable resistance branch is connected to the source terminal of the MOSFET. A first terminal of the second diode is connected to the gate terminal of the GaN power transistor, and a second terminal of the second diode is connected to the first terminal of the second adjustable resistance branch. The second terminal of the second adjustable resistance branch is connected to the source terminal of the MOSFET. The first adjustable resistance branch adjusts its first adjustable resistance in response to a first switch control signal from the logic control module, and the second adjustable resistance branch adjusts its second adjustable resistance in response to a second switch control signal from the logic control module.

8. The control device as claimed in claim 7, wherein, The first adjustable resistance branch includes: at least two fourth resistors connected in series and a switch connected in parallel with each of the at least two fourth resistors, wherein the switch connected in parallel with each of the at least two fourth resistors is independently controlled to be turned on or off in response to a first switch control signal from the logic control module; the second adjustable resistance branch includes: at least two fifth resistors connected in series and a switch connected in parallel with each of the at least two fifth resistors, wherein the switch connected in parallel with each of the at least two fifth resistors is independently controlled to be turned on or off in response to a second switch control signal from the logic control module.

9. The control device according to any one of claims 1 to 8, further comprising a voltage clamping circuit configured to clamp the voltage at the source terminal of the GaN power transistor to a clamping voltage at the moment of turn-off of the GaN power transistor, wherein, The voltage clamping circuit is connected to the source terminal of the GaN power transistor.

10. The control device as claimed in claim 9, wherein, The voltage clamping circuit includes a Zener diode, a fifth resistor, a sixth resistor, a seventh resistor, and a third power transistor. The first terminal of the Zener diode is connected to the source terminal of the GaN power transistor; the second terminal of the Zener diode is connected to the first terminal of the fifth resistor; the second terminal of the fifth resistor is connected to the first terminal of the sixth resistor; and the second terminal of the sixth resistor is grounded. The first terminal of the seventh resistor is connected to the source terminal of the GaN power transistor; the second terminal of the seventh resistor is connected to the drain terminal of the third power transistor; the gate terminal of the third power transistor is connected to the junction of the second terminal of the fifth resistor and the first terminal of the sixth resistor; and the source terminal of the third power transistor is grounded.

11. The control device as claimed in claim 5, wherein, The logic control module includes an eighth resistor, a ninth resistor, a comparator, and an SR flip-flop. The first terminal of the eighth resistor is connected to the feedback terminal, and the second terminal of the eighth resistor is connected to the first terminal of the ninth resistor, which is grounded. The positive input terminal of the comparator is connected to the junction of the second terminal of the eighth resistor and the first terminal of the ninth resistor, and the negative input terminal of the comparator is connected to the sampling terminal. The first input terminal of the SR flip-flop receives an oscillation signal generated by an oscillator, and the second input terminal of the SR flip-flop is connected to the output terminal of the comparator. The output terminal of the SR flip-flop is connected to the drive module.

12. The control device as claimed in claim 1, wherein, The GaN power transistor is a depletion-type GaN power transistor.

13. A switching power supply, comprising: The control device as described in any one of claims 1 to 12.

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