Low-cost gallium nitride power tube current detection protection device

Abstract

The invention discloses a low-cost gallium nitride power tube current detection and protection device, which comprises a voltage conversion module, a current detection and amplification circuit, an overcurrent comparison module, a fault latch circuit and an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) switching circuit, when gallium nitride power current is too large, the current is subjected to detection, amplification, comparison and fault latch, and the MOSFET switching circuit is turned off, so that the gallium nitride power tube is protected. According to the scheme, a digital circuit is not depended on, the adopted devices are simple and low in cost, the whole device is not prone to electromagnetic interference and high in reliability, and the requirement for high-voltage protection of the drain electrode can be met.

Description

Technical Field

[0001] This invention belongs to the field of radar power amplifiers, specifically relating to a low-cost gallium nitride power transistor current detection and protection device. Background Technology

[0002] With the increasing demand for high power and wide pulse width in modern radar systems, radar transmitter designs must be improved towards higher power density and higher peak current. As a result, gallium nitride power transistors, which have better broadband characteristics, high output power, and strong resistance to saturation input, have gradually become the preferred devices for transmission systems.

[0003] Gallium nitride (GaN) power transistors are typically powered by a negative gate voltage modulation and a high drain voltage. With continuous advancements in technology, the output power and operating voltage of GaN power transistors are constantly increasing. Generally, to achieve higher transmission power, radar transmitter components are designed using multiple GaN power transistors for combining, resulting in a larger operating current. Therefore, their safety is paramount. To prevent overcurrent from a single GaN power transistor failure, which could lead to the failure of the entire component, the need for single-transistor current monitoring and protection is urgent. Furthermore, radar transmitters have a large number of power transistors, and high-power radiation and direct electromagnetic interference from the circuitry are also significant. Therefore, the current detection and protection circuits for the power transistors need to be simple in structure, easy to implement, cost-effective, and have strong anti-interference capabilities.

[0004] Currently, the relevant protection circuits are not yet mature. Some require the intervention of digital circuits, which are costly and susceptible to electromagnetic interference. Others are designed for low gate modulation voltage control protection, but cannot cover the high drain voltage protection requirements. Summary of the Invention

[0005] To address the above problems, the present invention aims to provide a low-cost gallium nitride power transistor current detection and protection device.

[0006] The specific technical solution for achieving the objective of this invention is as follows:

[0007] A low-cost gallium nitride power transistor current detection and protection device includes a high-level voltage source, a gallium nitride power transistor, a voltage conversion module, a current detection amplification circuit, an overcurrent comparison module, a fault latching circuit, and a MOSFET switching circuit.

[0008] The high-level voltage source is connected to the current detection and amplification circuit, and the current detection and amplification circuit is connected to the MOSFET switching circuit; the MOSFET switching circuit is connected to the drain of the gallium nitride power transistor.

[0009] The output of the overcurrent comparator module is connected to the input of the fault latch circuit, and the output of the fault latch circuit is connected to the MOSFET switching circuit.

[0010] When the gallium nitride power current is too high, the current is detected, amplified, compared, and fault latched, which will turn off the MOSFET switching circuit, making the drain voltage of the gallium nitride power transistor zero and stopping its operation.

[0011] Furthermore, the current detection amplification circuit includes a current sampling amplification chip, a current detection resistor, a reference input resistor, and an output amplification resistor;

[0012] Wherein, one end of the current sensing resistor and the reference input resistor are connected to a high-level voltage source, and the other end of the current sensing resistor is connected to the input terminal of the current sampling amplifier chip and the MOSFET switching circuit; the other end of the reference input resistor is connected to the input terminal of the current sampling amplifier chip; the output terminal of the current sampling amplifier chip is connected to the output amplification resistor and the overcurrent comparison module, and the other end of the output amplification resistor is grounded.

[0013] Furthermore, the MOSFET switching circuit includes a driver chip and a PMOS transistor;

[0014] The driver chip is connected to a high-level voltage source, its control terminal is connected to a fault latch circuit, the output terminal of the driver chip is connected to the gate of the PMOS transistor to realize the on / off control, the source of the PMOS transistor is connected to a current detection amplifier circuit, and the drain of the PMOS transistor is connected to a gallium nitride power transistor.

[0015] Furthermore, the overcurrent comparison module includes a first voltage divider resistor, a second voltage divider resistor, and an operational amplifier;

[0016] One end of the first voltage divider resistor is connected to a +5V voltage, and the other end of the first voltage divider resistor is connected to the second voltage divider resistor and the positive input terminal of the operational amplifier. The negative input terminal of the operational amplifier is connected to the current detection amplifier circuit. The output terminal of the operational amplifier is connected to the fault latch circuit.

[0017] Furthermore, the fault latch circuit includes a pull-up resistor, an energy storage capacitor, and an RS flip-flop;

[0018] One end of the pull-up resistor is connected to a +5V voltage, and the other end is connected to the energy storage capacitor and the S port of the RS flip-flop. The other end of the energy storage capacitor is grounded. The R port of the RS flip-flop is the input terminal of the fault latch circuit and is connected to the output terminal of the overcurrent comparator module. The Q port of the RS flip-flop is the output port of the fault latch circuit and is connected to the MOSFET switching circuit.

[0019] Furthermore, the overcurrent comparison module generates a protection threshold voltage V through a first voltage divider resistor and a second voltage divider resistor. REF ;

[0020] The operational amplifier compares the protection threshold voltage V.REF The voltage output of the gallium nitride power transistor is compared with that output by the current sensing amplifier circuit. The output level of the RS flip-flop is controlled by the high or low level output of the operational amplifier. The drain voltage of the gallium nitride power transistor is controlled by the on / off state of the MOSFET switching circuit, thereby realizing the current sensing protection of the gallium nitride power transistor.

[0021] Furthermore, the protection threshold voltage V REF =5V*R4 / (R3+R4).

[0022] Furthermore, the resistance value of the current sensing resistor is within 5mΩ.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The present invention utilizes a voltage conversion module, a current detection and amplification circuit, an overcurrent comparison module, a fault latching circuit, and a MOSFET switching circuit. When the gallium nitride power current is too high, the current undergoes detection, amplification, comparison, and fault latching, which shuts off the MOSFET switching circuit, making the drain voltage of the gallium nitride power transistor zero and stopping its operation. This solution does not rely on digital circuits, and the components used are simple and low-cost. The entire device is not easily affected by electromagnetic interference, has high reliability, and can cover the requirements for high drain voltage protection.

[0025] The present invention will be further described below with reference to specific embodiments. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the low-cost gallium nitride power transistor current detection and protection device of the present invention. Detailed Implementation

[0027] Example

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0030] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0031] Combination Figure 1 A low-cost gallium nitride power transistor current detection and protection device includes a high-level voltage source, a gallium nitride power transistor, a voltage conversion module, a current detection amplification circuit, an overcurrent comparison module, a fault latching circuit, and a MOSFET switching circuit.

[0032] The high-level voltage source is used to provide the drain operating voltage of the gallium nitride power transistor. In this implementation, a pulsed gallium nitride power transistor with a 50V operating voltage is selected, and the peak operating current I... MAX Less than 20A.

[0033] The high-level voltage source is connected to the current detection and amplification circuit, and the current detection and amplification circuit is connected to the MOSFET switching circuit; the MOSFET switching circuit is connected to the drain of the gallium nitride power transistor.

[0034] The output of the overcurrent comparator module is connected to the input of the fault latch circuit, and the output of the fault latch circuit is connected to the MOSFET switching circuit.

[0035] The current flowing through the MOSFET switching circuit is converted into a voltage signal by the current detection and amplification circuit and sent to the overcurrent comparison module. The output of the overcurrent comparison module is connected to the input of the fault latch circuit, and the output of the fault latch circuit is connected to the driver chip in the MOSFET switching circuit. When the gallium nitride power current is too large, the current is detected, amplified, compared, and fault latched, which will turn off the MOSFET switching circuit, making the drain voltage of the gallium nitride power transistor zero and stopping its operation.

[0036] Specifically, the current detection amplifier circuit includes a current sampling amplifier chip, a current detection resistor R0, a reference input resistor R1, and an output amplification resistor R2;

[0037] Wherein, one end of the current sensing resistor R0 and the reference input resistor R1 are connected to a high-level voltage source, and the other end of the current sensing resistor R0 is connected to the IN1 input terminal of the current sampling amplifier chip and the MOSFET switching circuit; the other end of the reference input resistor R1 is connected to the IN2 input terminal of the current sampling amplifier chip; the output terminal of the current sampling amplifier chip is connected to the output amplification resistor R2 and the overcurrent comparison module, and the other end of the output amplification resistor R2 is grounded.

[0038] The current sensing resistor R0 is typically a small-value power resistor. When current flows through R0, a small voltage difference is generated. This voltage difference is fed into the current sensing amplifier circuit. By configuring resistor R1 and the output amplification resistor R2, the voltage difference can be amplified by different factors before being output. The current flows from the high-level voltage source, through the current sensing resistor R0, and then through the PMOS transistor to the gallium nitride power transistor. The current sampling amplifier chip obtains the voltage drop V0 across R0 through the IN1 and IN2 terminals, where V0 = I. MAX *R0, R0 is selected as a small-value power resistor, preferably within 5mΩ in the embodiment. At this time, the voltage drop across R0 is less than 0.1V, which has little impact on the voltage value obtained by the gallium nitride power supply at the back end, and its own power dissipation is also small.

[0039] The MOSFET switching circuit includes a driver chip and a PMOS transistor Q1;

[0040] The driver chip is connected to a high-level voltage source, its control terminal is connected to a fault latch circuit, the output terminal of the driver chip is connected to the gate of PMOS transistor Q1 to realize the on / off control, the source of PMOS transistor Q1 is connected to a current detection amplifier circuit, and the drain of PMOS transistor Q1 is the output terminal of the MOSFET switching circuit, which is connected to a gallium nitride power transistor.

[0041] The overcurrent comparison module includes a first voltage divider resistor R3, a second voltage divider resistor R4, and an operational amplifier;

[0042] In this circuit, one end of the first voltage divider resistor R3 is connected to a +5V voltage, and the other end of the first voltage divider resistor R3 is connected to the second voltage divider resistor R4 and the positive input terminal + of the operational amplifier. The negative input terminal - of the operational amplifier is connected to the current detection amplifier circuit. The output terminal of the operational amplifier is the output port of the overcurrent comparator module and is connected to the fault latch circuit. The first voltage divider resistor R3 and the second voltage divider resistor R4 divide the +5V voltage, and the voltage after voltage division is used as the protection threshold of the overcurrent comparator module and compared with the output voltage of the current detection amplifier circuit.

[0043] The fault latching circuit includes a pull-up resistor R5, an energy storage capacitor C1, and an RS flip-flop.

[0044] Wherein, one end of the pull-up resistor R5 is connected to a +5V voltage, and the other end is connected to the energy storage capacitor C1 and the S port of the RS flip-flop. The other end of the energy storage capacitor C1 is grounded. The R port of the RS flip-flop is the input terminal of the fault latch circuit and is connected to the output terminal of the overcurrent comparator module. The Q port of the RS flip-flop is the output port of the fault latch circuit and is connected to the MOSFET switching circuit. The pull-up resistor R5 charges the energy storage capacitor C1 during the initial power-on phase, causing the S port of the RS flip-flop to delay and become high.

[0045] The overcurrent comparison module generates a protection threshold voltage V through the first voltage divider resistor R3 and the second voltage divider resistor R4. REF ;

[0046] The operational amplifier compares the protection threshold voltage V. REF The voltage output of the gallium nitride power transistor is compared with that output by the current sensing amplifier circuit. The output level of the RS flip-flop is controlled by the high or low level output of the operational amplifier. The drain voltage of the gallium nitride power transistor is controlled by the on / off state of the MOSFET switching circuit, thereby realizing the current sensing protection of the gallium nitride power transistor.

[0047] In this scheme, changing the values ​​of the output amplification resistor R2 and the reference input resistor R1 can change the amplification factor of the current sampling amplification chip. The amplified object is the voltage drop V0 on R0, the amplification factor is R2 / R1, and the amplified output is V1.

[0048] By changing the values ​​of voltage divider resistors R3 and R4, different protection threshold voltages V can be obtained by dividing the +5V voltage. REF V REF =5V*R4 / (R3+R4).

[0049] V1 enters the negative terminal of the operational amplifier, V REF When the operational amplifier is connected to the positive terminal, and the gallium nitride power transistor is either not working or working normally, V1 is less than V. REF The operational amplifier outputs a high level; when the gallium nitride power transistor is overcurrent, V1 is greater than V. REF The operational amplifier outputs a low level.

[0050] Pull-up resistor R5 is connected to +5V to charge energy storage capacitor C1. The voltage on C1 enters the S port of RS flip-flop; the R port of RS flip-flop is connected to the output of operational amplifier; the Q port of RS flip-flop is connected to the control port C of the driver chip of MOSFET switching circuit.

[0051] When this device is in operation, during the initial power-on phase, the gallium nitride power transistor is not working, and the current sampling voltage V1 is lower than the protection threshold voltage V. REFThe voltage V2 at port R of the RS flip-flop is high. During the initial power-up phase, the pull-up resistor R5 charges the energy storage capacitor C1, causing the S port of the RS flip-flop to remain low for a period of time during the initial power-up phase. At this time, the output voltage V3 at port Q of the RS flip-flop is high, and the MOSFET switching circuit is turned on. After the capacitor C1 has been charged for a period of time, the S port of the RS flip-flop becomes high, the RS flip-flop becomes in a hold state, and the output Q port maintains the high level of the previous state.

[0052] When gallium nitride power is operating, a transmitter fault causes excessive current, and the current sampling voltage V1 exceeds the protection threshold voltage V. REF When the voltage V2 at the R port of the RS flip-flop goes low, the S port of the RS flip-flop is high, causing the output voltage V3 at the Q port of the RS flip-flop to go low, and the MOSFET switching circuit is turned off; the gallium nitride power transistor stops working, causing V1 to decrease below V REF When the voltage V2 at port R of the RS flip-flop goes high, port S of the RS flip-flop remains high, the RS flip-flop enters a hold state, port Q of the output remains low, and the MOSFET switching circuit remains off.

[0053] The present invention utilizes a voltage conversion module, a current detection and amplification circuit, an overcurrent comparison module, a fault latching circuit, and a MOSFET switching circuit. When the gallium nitride power current is too high, the current undergoes detection, amplification, comparison, and fault latching, which shuts off the MOSFET switching circuit, making the drain voltage of the gallium nitride power transistor zero and stopping its operation. This solution does not rely on digital circuits, and the components used are simple and low-cost. The entire device is not easily affected by electromagnetic interference, has high reliability, and can cover the requirements for high drain voltage protection.

[0054] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A low-cost gallium nitride power transistor current detection and protection device, characterized in that, It includes a high-level voltage source, gallium nitride power transistor, voltage conversion module, current detection and amplification circuit, overcurrent comparison module, fault latch circuit and MOSFET switching circuit; The high-level voltage source is connected to the current detection and amplification circuit, and the current detection and amplification circuit is connected to the MOSFET switching circuit; the MOSFET switching circuit is connected to the drain of the gallium nitride power transistor. The output of the overcurrent comparator module is connected to the input of the fault latch circuit, and the output of the fault latch circuit is connected to the MOSFET switching circuit. When the gallium nitride power current is too high, the current is detected, amplified, compared, and fault latched, which will turn off the MOSFET switching circuit, making the drain voltage of the gallium nitride power transistor zero and stopping its operation.

2. The low-cost gallium nitride power transistor current detection and protection device according to claim 1, characterized in that, The current detection amplifier circuit includes a current sampling amplifier chip, a current detection resistor (R0), a reference input resistor (R1), and an output amplification resistor (R2). In this circuit, one end of the current sensing resistor (R0) and the reference input resistor (R1) is connected to a high-level voltage source, and the other end of the current sensing resistor (R0) is connected to the input terminal of the current sampling amplifier chip and the MOSFET switching circuit; the other end of the reference input resistor (R1) is connected to the input terminal of the current sampling amplifier chip; the output terminal of the current sampling amplifier chip is connected to the output amplification resistor (R2) and the overcurrent comparator module, and the other end of the output amplification resistor (R2) is grounded.

3. The low-cost gallium nitride power transistor current detection and protection device according to claim 1, characterized in that, The MOSFET switching circuit includes a driver chip and a PMOS transistor (Q1). The driver chip is connected to a high-level voltage source, its control terminal is connected to a fault latch circuit, the output terminal of the driver chip is connected to the gate of the PMOS transistor (Q1) to realize the on / off control, the source of the PMOS transistor (Q1) is connected to a current detection amplifier circuit, and the drain of the PMOS transistor (Q1) is connected to a gallium nitride power transistor.

4. The low-cost gallium nitride power transistor current detection and protection device according to claim 1, characterized in that, The overcurrent comparison module includes a first voltage divider resistor (R3), a second voltage divider resistor (R4), and an operational amplifier; One end of the first voltage divider resistor (R3) is connected to a +5V voltage, and the other end of the first voltage divider resistor (R3) is connected to the second voltage divider resistor (R4) and the positive input terminal (+) of the operational amplifier. The negative input terminal (-) of the operational amplifier is connected to the current detection amplifier circuit. The output terminal of the operational amplifier is connected to the fault latch circuit.

5. The low-cost gallium nitride power transistor current detection and protection device according to claim 4, characterized in that, The fault latch circuit includes a pull-up resistor (R5), an energy storage capacitor (C1), and an RS flip-flop; The pull-up resistor (R5) is connected to a +5V voltage at one end and to the energy storage capacitor (C1) and the S port of the RS flip-flop at the other end. The other end of the energy storage capacitor (C1) is grounded. The R port of the RS flip-flop is the input terminal of the fault latch circuit and is connected to the output terminal of the overcurrent comparator module. The Q port of the RS flip-flop is the output port of the fault latch circuit and is connected to the MOSFET switching circuit.

6. The low-cost gallium nitride power transistor current detection and protection device according to claim 5, characterized in that, The overcurrent comparison module generates a protection threshold voltage V through the first voltage divider resistor (R3) and the second voltage divider resistor (R4). REF ; The operational amplifier compares the protection threshold voltage V. REF The voltage output of the gallium nitride power transistor is compared with that output by the current sensing amplifier circuit. The output level of the RS flip-flop is controlled by the high or low level output of the operational amplifier. The drain voltage of the gallium nitride power transistor is controlled by the on / off state of the MOSFET switching circuit, thereby realizing the current sensing protection of the gallium nitride power transistor.

7. The low-cost gallium nitride power transistor current detection and protection device according to claim 6, characterized in that, The protection threshold voltage V REF =5V*R4 / (R3+R4).

8. The low-cost gallium nitride power transistor current detection and protection device according to claim 2, characterized in that, The resistance of the current sensing resistor (R0) is within 5mΩ.

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