GAN power circuit and GAN power driving device

Abstract

A gallium nitride (GaN) power circuit includes a low-potential terminal, a power supply terminal, a drive input terminal, a GaN power element, a first enhancement-mode transistor, and a depletion-mode transistor. The GaN power element is connected in series between the power supply terminal and the low-potential terminal. The drain of the first enhancement-mode transistor is electrically connected to the gate of the GaN power element, and its gate and source are electrically connected to the drive input terminal. The drain of the depletion-mode transistor is electrically connected to the gate of the GaN power element, its gate is electrically connected to the source of the GaN power element, and its source is electrically connected to the drive input terminal. This improves the threshold voltage seen at the drive input terminal, thereby enhancing noise immunity without impacting reverse conduction efficiency.

Description

Technical Field

[0001] This invention relates to a power circuit and a driving power device, and more particularly to a gallium nitride power circuit and a gallium nitride driving power device. Prior Technology

[0002] Third-generation semiconductor materials are based on wide bandgap compound materials, represented by silicon carbide (SiC) and gallium nitride (GaN). Due to their superior material properties, high carrier mobility, and high bandgap, for example, the FOM of gallium nitride (GaN) devices is 5 to 10 times higher than that of Si devices. This gives them great potential to replace Si devices in high-voltage and high-power applications, and they can be used in higher-order high-voltage power devices and high-frequency communication devices.

[0003] Referring to Figure 1, a gallium nitride (GaN) power device 11 and a driver 12 are shown. The GaN power device 11 and the driver 12 are located in different packages, hence separated by dashed lines. The driver 12 is electrically connected to a drive power supply Vcc, receives an input signal Vin, and outputs a drive signal Vout to the gate of the GaN power device 11. The GaN power device 11 is electrically connected between a power supply Vds and a low voltage Vss, and is turned on or off according to the drive signal Vout. In high-frequency applications, the rapid switching of the GaN power device 11 can cause noise at the gate, that is, it can interfere with the drive signal Vout, leading to malfunction of the GaN power device 11.

[0004] There are currently two solutions. One is to adjust the process parameters to increase the threshold voltage (Vth) of the gallium nitride power device 11. By increasing the threshold voltage of the gallium nitride power device 11, the ability to resist gate noise (i.e., noise of the drive signal Vout) can be increased. However, the drawback of this method is that it leads to poor reverse conduction efficiency.

[0005] The second solution, as shown in Figure 2, involves placing a pre-drive circuit 13 at the gate of the gallium nitride power element 11 and integrating the pre-drive circuit 13 with the gallium nitride power element 11 via integration or co-package (as shown by the dashed box in Figure 2). By controlling the operation of the pre-drive circuit 13, the threshold voltage of the integrated circuit (the threshold voltage seen from the driver 12 terminal) is increased. The pre-drive circuit 13 can also serve as a transmission medium for the drive signal Vout, thereby reducing the noise impact of the drive signal Vout. However, the pre-drive circuit 13 requires an additional pre-drive power supply Vdd, which necessitates the addition of an external drive circuit 14 (including a diode 141 and a capacitor 142) outside the integrated circuit of the gallium nitride power element 11 to maintain the stability of the pre-drive power supply Vdd. Furthermore, the integrated circuit of the gallium nitride power element 11 also requires an additional pin to connect to the external drive circuit 14. Therefore, this method is not only complex in its control, but also occupies a large area both inside and outside the integrated circuit of the gallium nitride power device 11, and also occupies additional pins, resulting in high costs. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a gallium nitride power circuit that can solve the above-mentioned problems.

[0007] Therefore, the gallium nitride power circuit of the present invention includes a low potential terminal, a power supply terminal, a drive input terminal, a gallium nitride power element, a first enhancement-mode transistor, and a depletion-mode transistor.

[0008] This power supply terminal is suitable for receiving a power source.

[0009] This drive input is suitable for receiving a drive signal.

[0010] The gallium nitride power device is connected in series between the power supply terminal and the low potential terminal.

[0011] The drain of the first enhancement transistor is electrically connected to the gate of the gallium nitride power device, and its gate and source are electrically connected to the drive input terminal.

[0012] The drain of the depleted transistor is electrically connected to the gate of the gallium nitride power device, the gate is electrically connected to the source of the gallium nitride power device, and the source is electrically connected to the drive input terminal.

[0013] Therefore, the object of the present invention is to provide a gallium nitride driving power device that can solve the above-mentioned problems.

[0014] Therefore, the gallium nitride driving power device of the present invention includes a low potential terminal, a power supply terminal, a driving power supply terminal, a control input terminal, a driver, a gallium nitride power element, a first enhancement-mode transistor, and a depletion-mode transistor.

[0015] This power supply terminal is suitable for receiving a power source.

[0016] This drive power supply terminal is suitable for receiving a drive power supply.

[0017] This control input is suitable for receiving an input signal.

[0018] The driver is electrically connected to the drive power supply terminal, the low potential terminal, and the control input terminal. The control input terminal receives the input signal and outputs a corresponding drive signal.

[0019] The gallium nitride power device is connected in series between the power supply terminal and the low potential terminal.

[0020] The drain of the first enhancement transistor is electrically connected to the gate of the gallium nitride power element, and its gate and source are electrically connected to the driver to receive the drive signal.

[0021] The drain of the depleted transistor is electrically connected to the gate of the gallium nitride power element, the gate is electrically connected to the source of the gallium nitride power element, and the source is electrically connected to the driver to receive the drive signal.

[0022] The advantages of this invention are as follows: by setting the first enhanced transistor and electrically connecting the gate of the first enhanced transistor to the source, the threshold voltage seen at the drive input terminal can be increased, thereby improving noise immunity. Furthermore, by providing a discharge path with the depletion transistor, this implementation can improve the threshold voltage without impacting reverse conduction efficiency. Simple Explanation of the Diagram

[0023] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is a circuit diagram of a conventional gallium nitride power device and a driver; Figure 2 is a circuit diagram of a conventional gallium nitride power device, a driver, a front-end drive circuit, and an external drive circuit; Figure 3 is a circuit diagram of a first embodiment of the gallium nitride driving power device of the present invention; Figure 4 is a graph of drain current versus gate-source voltage, illustrating the difference between this first embodiment and a conventional simulation curve; Figure 5 is a graph of source-drain current versus source-drain voltage, illustrating the first embodiment and a conventional simulation curve; and Figure 6 is a circuit diagram of a second embodiment of the gallium nitride driving power device of the present invention. Implementation

[0024] Before the invention is described in detail, it should be noted that similar elements are represented by the same numbers in the following description.

[0025] Referring to Figure 3, a first embodiment of a gallium nitride driving power device of the present invention includes a low potential terminal 2, a power supply terminal 3, a driving power supply terminal 4, a control input terminal 5, a driver 6, and a gallium nitride power circuit 7.

[0026] The low potential terminal 2 provides a low voltage Vss, which in this embodiment is described as the ground voltage (Gnd, 0V).

[0027] The power supply terminal 3 is suitable for receiving a power supply Vds. The drive power supply terminal 4 is suitable for receiving a drive power supply Vcc.

[0028] The control input terminal 5 is used to receive an input signal Vin. This input signal Vin is output by a control circuit (not shown) at the front end, and is generally a pulse signal.

[0029] The driver 6 is electrically connected to the drive power supply terminal 4, the low potential terminal 2, and the control input terminal 5. The control input terminal 5 receives the input signal Vin and outputs a corresponding drive signal Vout. The driver 6 can be implemented using a gate driver to amplify the driving capability of the input signal Vin and output the drive signal Vout with a phase corresponding to the input signal Vin.

[0030] The gallium nitride power circuit 7 has a low potential terminal 2, a power supply terminal 3, a drive input terminal 71, a gallium nitride power element 72, a first enhancement transistor 73, and a depletion transistor 74.

[0031] The drive input terminal 71 is electrically connected to the driver 6 and is used to receive the drive signal Vout.

[0032] The gallium nitride (GaN) power device 72 is connected in series between the power supply terminal 3 and the low potential terminal 2. Its drain is electrically connected to the power supply terminal 3, and its source is electrically connected to the low potential terminal 2. It is turned on or off according to the drive signal Vout. The gallium nitride power device 72 is an enhancement-mode gallium nitride high electron mobility transistor (Enhancement-mode GaN HEMT, or E-mode GaN HEMT).

[0033] The drain of the first enhancement-mode transistor 73 is electrically connected to the gate of the gallium nitride power element 72, and its gate is connected to the source. It is also electrically connected to the drive input terminal 71 to receive the drive signal Vout. The first enhancement-mode transistor 73 is an enhancement-mode gallium nitride high electron mobility transistor.

[0034] The drain of the depletion-mode transistor 74 is electrically connected to the gate of the gallium nitride power element 72, and its gate is electrically connected to the source of the gallium nitride power element 72. Its source is electrically connected to the drive input terminal 71 to receive the drive signal Vout. The depletion-mode transistor 74 is a depletion-mode gallium nitride high electron mobility transistor (Depletion-mode GaN HEMT, or D-mode GaN HEMT).

[0035] The gallium nitride power device 72, being a power device, has a larger size to enhance its voltage withstand and current handling capabilities. The first enhancement-mode transistor 73 and the depletion-mode transistor 74, since voltage withstand capability is not a concern, can be implemented using logic devices. That is, the sizes of the first enhancement-mode transistor 73 and the depletion-mode transistor 74 are smaller than the size of the gallium nitride power device 72, and they can be implemented using transistors conforming to minimum design rules. Furthermore, the gallium nitride power device 72, the first enhancement-mode transistor 73, and the depletion-mode transistor 74 are integrated on the same wafer using the same manufacturing process.

[0036] Refer to Figures 3, 4, and 5 for practical application instructions:

[0037] When the drive signal Vout is high, the first enhancement transistor 73 is turned on (threshold voltage, for example, 1.5V), while the depletion transistor 74 is not turned on (threshold voltage, for example, -0.8V). Because the gate and source of the first enhancement transistor 73 are electrically connected, it forms the characteristics of a diode. The threshold voltage of this diode (e.g., 1.5V) is superimposed on the original threshold voltage (e.g., 1.5V) of the gallium nitride power element 72, thus increasing the overall threshold voltage seen at the drive input terminal 71. As shown in Figure 4, Figure 4 is a graph of the drain-to-source current Ids versus the gate-to-source voltage Vgs of the gallium nitride power element 72. Curve 91 is the conventional (Figure 1) simulated curve when only the gallium nitride power element 72 is used, and curve 92 is the simulated curve of the gallium nitride power circuit 7 in this embodiment. As can be seen from Figure 4, the threshold voltage Vth2 (e.g., 3V) of the gallium nitride power circuit 7 is higher than the conventional threshold voltage Vth1 (e.g., 1.5V), and the difference is the threshold voltage of the diode of the first enhancement transistor 73. Therefore, this embodiment can indeed improve the ability to resist noise from the drive signal Vout.

[0038] When the drive signal Vout is low, the first enhancement-mode transistor 73 switches off, while the depletion-mode transistor 74 switches on, providing a discharge path for the input capacitor Ciss of the gate of the gallium nitride power element 72. That is, the charge on the input capacitor Ciss can be discharged through the drain and source of the depletion-mode transistor 74. Figure 5 shows a graph of the source-to-drain current Isd versus the source-to-drain voltage Vsd of the gallium nitride power element 72. Curve 93 is the conventional (Figure 1) simulation curve when only the gallium nitride power element 72 is present, and the simulation curve of the gallium nitride power circuit 7 in this embodiment also coincides with curve 93. In other words, by providing a discharge path through the depletion-mode transistor 74, the gallium nitride power circuit 7 in this embodiment does not affect the reverse conduction efficiency when the threshold voltage is increased.

[0039] Based on the above explanation, the advantages of the aforementioned embodiments can be summarized as follows:

[0040] By providing the first enhanced transistor 73 and connecting its gate to the source, the threshold voltage seen at the drive input terminal 71 can be increased, thereby improving noise immunity. Furthermore, by providing the depletion transistor 74 to offer a discharge path, this embodiment can improve the threshold voltage without impacting reverse conduction efficiency. Compared to conventional technology, this first embodiment can solve the noise interference problem at a low cost, without requiring additional drive circuitry or power supply, and without affecting reverse conduction efficiency. Therefore, this first embodiment has excellent market potential.

[0041] Referring to Figure 6, a second embodiment of the gallium nitride driving power device of the present invention is shown. This second embodiment is similar to the first embodiment, but the difference between the second embodiment and the first embodiment is:

[0042] The second embodiment further includes a second enhancement transistor 75, which is connected in series between the drain of the first enhancement transistor 73 and the gate of the gallium nitride power element 72. The second enhancement transistor 75 is an enhancement-mode gallium nitride high electron mobility transistor.

[0043] The drain of the second enhancement-mode transistor 75 is electrically connected to the gate of the gallium nitride power element 72, and its gate is connected to the source, and is also electrically connected to the drain of the first enhancement-mode transistor 73. Similarly, due to the connection between the drain and source of the second enhancement-mode transistor 75, a diode characteristic is formed, and the threshold voltage of this diode (e.g., 1.5V) can be superimposed on the threshold voltages of the gallium nitride power element 72 and the first enhancement-mode transistor 73. In this way, the threshold voltage seen at the drive input terminal 71 can be further increased, thereby improving noise immunity.

[0044] The second enhanced transistor 75 can also be implemented using logic elements, meaning its size is smaller than that of the gallium nitride power element 72, and it can be implemented using transistors that conform to minimum design rules. Furthermore, the second enhanced transistor 75, the gallium nitride power element 72, the first enhanced transistor 73, and the depletion transistor 74 are integrated on the same chip using the same process.

[0045] Thus, the second embodiment can achieve the same purpose and effect as the first embodiment described above. Furthermore, by connecting the first enhanced transistor 73 and the second enhanced transistor 75 in series, the threshold voltage can be further increased, thereby further improving the noise immunity.

[0046] In summary, the gallium nitride power circuit and gallium nitride driving power device of the present invention do indeed achieve the purpose of the present invention.

[0047] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification shall still fall within the scope of the patent of the present invention.

[0048] 2: Low potential end 3: Power supply terminal 4: Drive power supply terminal 5: Control Input Terminal 6: Driver 7: Gallium Nitride Power Circuit 71: Driver Input Terminal 72: Gallium Nitride Power Devices 73: First Enhancement Transistor 74: Depletion-type transistor 75: Second Enhancement Transistor 91~93: Curves Vcc: Power supply Vds: Power supply Vss: Low voltage Vin: Input signal Vout: Drive signal Ids: Drain current Vgs: Gate-source voltage Isd: Source / Drain Current Vsd: Source / Drain Voltage Vth1: Known threshold voltage Vth2: Threshold voltage of gallium nitride power circuit

Claims

1. A gallium nitride (GaN) power circuit, comprising: a low-potential terminal; a power supply terminal for receiving a power supply; a drive input terminal for receiving a drive signal; a GaN power element connected in series between the power supply terminal and the low-potential terminal; a first enhancement-mode transistor, the drain of which is electrically connected to the gate of the GaN power element, and the gate and source of which are electrically connected to the drive input terminal, wherein the first enhancement-mode transistor is an enhancement-mode GaN high electron mobility transistor; and a depletion-mode transistor, the drain of which is electrically connected to the gate of the GaN power element, the gate of which is electrically connected to the source of the GaN power element, and the source of which is electrically connected to the drive input terminal, wherein the depletion-mode transistor is a depletion-mode GaN high electron mobility transistor.

2. The gallium nitride power circuit of claim 1 further includes a second enhancement transistor connected in series between the drain of the first enhancement transistor and the gate of the gallium nitride power element.

3. The gallium nitride power circuit as described in claim 2, wherein, The drain of the second enhancement transistor is electrically connected to the gate of the gallium nitride power device, and its gate and source are electrically connected to the drain of the first enhancement transistor.

4. The gallium nitride power circuit as described in claim 2, wherein, The second enhanced transistor is an enhanced gallium nitride high electron mobility transistor.

5. A gallium nitride (GaN) driving power device, comprising: a low-potential terminal; a power supply terminal adapted to receive a power supply; a driving power supply terminal adapted to receive a driving power supply; a control input terminal adapted to receive an input signal; a driver electrically connected to the driving power supply terminal, the low-potential terminal, and the control input terminal, wherein the control input terminal receives the input signal and outputs a corresponding driving signal; a gallium nitride power element connected in series between the power supply terminal and the low-potential terminal; a first enhancement-mode transistor, the drain of which is electrically connected to the gate of the gallium nitride power element, and the gate and source of which are electrically connected to the driver to receive the driving signal, wherein the first enhancement-mode transistor is an enhancement-mode gallium nitride high electron mobility transistor; and a depletion-mode transistor, the drain of which is electrically connected to the gate of the gallium nitride power element, the gate of which is electrically connected to the source of the gallium nitride power element, and the source of which is electrically connected to the driver to receive the driving signal, wherein the depletion-mode transistor is a depletion-mode gallium nitride high electron mobility transistor.

6. The gallium nitride driving power device as claimed in claim 5 further includes a second enhancement transistor connected in series between the drain of the first enhancement transistor and the gate of the gallium nitride power element.

7. The gallium nitride drive power device as claimed in claim 6, wherein, The drain of the second enhancement transistor is electrically connected to the gate of the gallium nitride power device, and its gate and source are electrically connected to the drain of the first enhancement transistor.

8. The gallium nitride drive power device as claimed in claim 6, wherein, The second enhanced transistor is an enhanced gallium nitride high electron mobility transistor.

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