Safe power supply circuit of gallium nitride power tube

Abstract

The invention discloses a safe power supply circuit of a gallium nitride power tube, which comprises a field effect switch, a triode, a diode and a resistor, and is characterized in that negative bias voltage is utilized to control the conduction of the field effect switch tube through the diode and the triode, so that power supply voltage is controlled to be loaded to a drain electrode of the GaN power tube; the grid bias voltage of the GaN power tube can ensure that the quiescent current of the power tube reaches a set value, at the moment, the negative bias voltage controls the field effect switch tube to connect the power supply to the drain electrode of the GaN power tube through the diode and the triode, and the power supply safety of the GaN power tube in the three states of power-on, power-off and reference negative bias voltage failure is ensured. By means of the mode, the GaN power tube safe power supply circuit is completely achieved through a hardware circuit, is simple in composition, reliable in work, low in cost, high in cost performance, quite suitable for safe power supply of a GaN power tube and good in practicability.

Description

Technical Field

[0001] The present invention relates to the technical field of power control circuits, and in particular to a safe power supply circuit for a gallium nitride power tube. Background Art

[0002] GaN power tubes are widely used in ultra-short wave and microwave amplifiers due to their high efficiency, good linearity, wide operating frequency band, wide operating voltage range and many other advantages. They are also popularized in various base station communications, mobile communications, and satellite communications equipment. However, the power supply of GaN power tubes has timing requirements: first add the negative bias voltage of the power tube gate, then provide positive power to the drain, and the timing cannot be reversed, otherwise the GaN power tube will be damaged. Usually, the following three groups of situations are likely to cause timing errors and damage the power tube:

[0003] (1) During the manual power-on process of the power amplifier circuit, during the debugging, testing and normal use of the circuit, the operator needs to manually control the gate bias first and then the drain voltage. Frequent operation can easily cause the wrong timing and damage the amplifier power tube;

[0004] (2) During the operation of the circuit, the reference negative power supply that provides bias to the gate of the GaN power tube suddenly fails. If the power supply cannot be turned off in time, the GaN power tube will be damaged;

[0005] (3) During the power-off process, the GaN power tube gate bias and drain power supply power-off timing errors will cause damage to the GaN power tube.

[0006] At present, most gallium nitride power amplifiers use special timing control circuits to ensure the power supply safety of the power tube. There are special timing control chips that first output negative bias to the gate of the GaN power tube. After a delay, the chip outputs a control signal to turn on the drain power switch, and delays the power supply to the drain of the GaN power tube, thereby ensuring the power supply safety of the GaN power tube. The power supply control circuit of the power tube is relatively complex and lacks a simple power supply control circuit. In general, the power supply of the GaN power tube has timing requirements, and the traditional power supply timing control circuit is relatively complex. There is also a problem of protecting the GaN power tube due to negative bias power failure during the power supply process.

[0007] Based on the above defects and shortcomings, it is necessary to improve the existing technology and design a safe power supply circuit for gallium nitride power tubes. Summary of the invention

[0008] The main technical problem solved by the present invention is to provide a safe power supply circuit for a gallium nitride power tube, which provides safe and reliable power supply for the GaN power tube in three situations: "power on", "power off" and "reference negative voltage failure". The circuit adopts universal discrete components, has a simple composition, a small board area, extremely low processing cost, no debugging required, reliable operation, and is suitable for mass replication.

[0009] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a safe power supply circuit for a gallium nitride power tube, the safe power supply circuit for the gallium nitride power tube includes a field effect switch V1, a transistor V2, a diode V3, a resistor R1, a resistor R2, a resistor R3 and a resistor R4, the emitter of the transistor V2 is connected to a reference negative power supply -Vs for supplying a gate bias of the GaN power tube, the base of the transistor V2 is connected to the positive electrode of the diode V3 through the resistor R1, the negative electrode of the diode V3 is grounded, one end of the resistor R2 is connected to the base of the transistor V2, and the other end is connected to the emitter of the transistor V2, the collector of the transistor V2 is connected to the power supply Vcc for supplying a drain voltage of the GaN power tube through the resistors R3 and R4;

[0010] The reverse conduction voltage Vr of the diode V3 is configured as Vr≤-(-Vs+0.7+VR1), where VR1 is the voltage drop across the resistor R1;

[0011] The gate of the field effect switch V1 is connected to the connection point of the resistors R3 and R4, the source of the field effect switch V1 is connected to the power supply Vcc that supplies the drain voltage of the GaN power tube, and the drain of the field effect tube V1 serves as the output end of the circuit and is connected to the drain circuit of the protected GaN power tube.

[0012] Preferably, the field effect switch V1 is configured as a P-channel metal oxide field effect transistor (P-MOSFET).

[0013] Preferably, the values ​​of the resistor R3 and the resistor R4 ensure that the voltage between the gate and the source when the field effect switch tube V1 is turned on is controlled between 8 and 11V, and the current passing through the resistor R3 and the resistor R4 is in the milliampere level.

[0014] Preferably, the transistor V2 is an NPN transistor.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The hardware circuit using only 7 discrete components realizes the protection of power devices in power-on, power-off and negative pressure failure states. By selecting the diode reverse conduction voltage Vr, it is ensured that the negative power supply voltage is lower than the threshold before the electronic switch is turned on to supply power to the drain of the power tube. Compared with the existing technical solutions using integrated chips or software control methods, the present invention is simple to implement, low in cost, good in reliability, and easy to mass produce. It can be used in base station communications, mobile communications, satellite communications and interference technology, and has been actually applied in microwave power amplifiers for base station communication interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The schematic diagram is a safe power supply circuit for a gallium nitride power tube.

[0018] Figure 2 This is the schematic diagram of the power supply control circuit.

[0019] Figure 3 This is the schematic diagram of the power switch circuit.

[0020] Figure 4 The output waveform diagram of a safe power supply circuit for a gallium nitride power tube during the power-on process.

[0021] Figure 5 The output waveform diagram of a safe power supply circuit of a gallium nitride power tube during the power-off process.

[0022] Figure 6 This is a waveform diagram of the output of a reference negative power supply in a safe power supply circuit for a gallium nitride power tube when power is lost midway.

[0023] Figure 7 This is a waveform diagram of the output recovery after a reference negative power supply of a safe power supply circuit for a gallium nitride power tube fails. DETAILED DESCRIPTION

[0024] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0025] See also Figures 1 to 7 , the embodiment of the present invention includes:

[0026] A safe power supply circuit for a gallium nitride power tube, the safe power supply circuit for the gallium nitride power tube comprising a power supply control circuit 1 and a power supply switch circuit 2, such as Figure 1 shown.

[0027] The power supply control circuit 1 includes an NPN transistor V2, a diode V3, a resistor R1 and a resistor R2. The emitter E of the NPN transistor V2 is connected to a reference negative power supply -Vs for supplying a gate bias to the GaN power tube. The base B of the NPN transistor V2 is connected to the positive electrode of the diode V3 through the resistor R1. The negative electrode of the diode V3 is grounded. One end of the resistor R2 is connected to the base of the NPN transistor V2, and the other end is connected to the emitter of the voltage-stabilizing transistor V2. The collector C of the NPN transistor V2 is connected to the power supply Vcc for supplying a drain voltage to the GaN power tube through the resistors R3 and R4. Figure 2 As shown, the control circuit part 1It is mainly used to control the impedance of the collector 11 to the emitter 12 of the NPN transistor V2 to be high or low resistance. When the reference negative power supply -Vs applied to the emitter 12 is invalid, the BE junction of the NPN transistor V2 is turned off and the CE junction is in a high resistance state; when the reference negative power supply -Vs applied to the emitter 12 is valid, the BE junction of the NPN transistor V2 is turned on and the CE junction is in a low resistance state. The diode V3 is used for voltage clamping to ensure that the BE junction of the NPN transistor V2 is turned on when the reference negative power supply reaches close to -Vs. The resistors R1 and R2 play the role of current limiting and voltage dividing, and control the NPN transistor V2 at the BE junction conduction current within milliamperes.

[0028] The power supply switch circuit 2 includes a field effect switch V1, a resistor R3 and a resistor R4. The gate G22 of the field effect switch V1 is connected to the connection point of the resistors R3 and R4. The source S23 of the field effect switch V1 is connected to the power supply Vcc for supplying the drain voltage of the GaN power tube. The drain D24 of the field effect tube V1 is connected to the drain circuit of the protected GaN power tube as the output end of the circuit. Figure 3 shown.

[0029] When the pin 21 of the resistor R3 is connected to a high resistance, no current flows through the resistors R3 and R4, and the voltage divided to the gate 22 of the field effect switch V1 is the same as the voltage of the source 23 of the field effect switch V1, both of which are the Vcc input voltage. The gate of the field effect switch V1 is not turned on, and the source-drain of the field effect switch V1 is turned off, that is, the drain 24 Vcc output = 0V, and the power supply of the GaN power tube is cut off; when the pin 21 of the resistor R3 is connected to a low resistance, the Vcc input voltage is divided by the resistors R3 and R4, and the voltage of the gate 22 of the field effect switch V1 is about 10V lower than the voltage of the source 23 of the field effect switch V1, and the source-drain of the field effect switch V1 is fully turned on, that is, the Vcc input is connected to the drain 24 through the source 23 of the field effect switch V1, and at this time, the Vcc output ≈ Vcc input, and the power supply of the GaN power tube is turned on.

[0030] The working principle of the safe power supply circuit of the gallium nitride power tube of the present invention is simple, and the implementation thereof is based on the following four key points:

[0031] First point: The control signal in the power supply control circuit 1 comes from the reference negative power supply -Vs that provides bias for the GaN power tube.

[0032] The second point: The selection of the clamping voltage value of the Zener diode V3 in the power supply control circuit 1 is related to the reference negative power supply. It is smaller than the absolute value of the reference negative power supply minus the BE junction voltage drop of transistor V1 0.7V and the voltage drop of resistor R1. Resistor R3 limits the current to about 0.2mA, and the voltage drop value is about 0.2V. For example, in this example, the absolute value of the reference negative power supply is 6.5V, minus 0.7V and 0.2V to get 5.6V. We choose a Zener diode that is ≤5.6V and is relatively close to the 5.6V Zener diode.

[0033] The third point: the resistance value selection of resistor R4 in the power supply switch circuit 2, the source-gate voltage value VGS of the field effect switch V1 = (Vcc voltage value + absolute value of the reference negative power supply) × R4 / (R3+R4), when VGS = about 10V, the field effect switch V1 works safely, and the presence or absence of VGS voltage can control the source-drain of the field effect switch V1 to be completely turned on or off. Taking Vcc = 48V as an example, the resistor R4 is 7.5KΩ, then the calculated resistance value of R3 is 33.375KΩ≈33KΩ, and the resistor R3 takes the conventional resistance value of 33KΩ.

[0034] Fourth point: The field effect switch V1 should be a P-channel field effect tube with small internal resistance and large current capacity. It generates little heat when the power is turned on and is easy to install.

[0035] The gate drive current of the P-channel field effect switch tube V1 that controls the power switch is less than the milliampere level, so the diode V3, the transistor V2, and the resistor can all be small chip devices, which are suitable for miniaturized design. After the parameters of the safe power supply circuit are determined, they are all chip devices, and the welding and debugging are very simple (if the device is welded correctly, debugging is not required), which is conducive to mass production and processing.

[0036] Figure 4-Figure 7 In the figure, the yellow waveform is the -6.5V reference negative power supply voltage waveform, and the green waveform is the Vcc output waveform corresponding to the GaN power tube drain voltage.

[0037] Figure 4 :When the negative bias voltage of the power supply protection circuit does not reach the reference negative power supply voltage (-6.5V in this case) (yellow waveform), the output voltage of V1 is 0V (green waveform). When the negative bias voltage basically reaches -6.5V, V1 outputs V㏄;

[0038] Figure 5 : Normal power-off output waveform (green waveform), starting with 80ms power-off decay waveform, followed by the power supply protection circuit action (i.e. yellow control level waveform), the main power supply voltage is quickly shut down to 0;

[0039] Figure 6: When the reference negative power supply loses power midway (yellow voltage waveform, the voltage changes from -6.5V to 0V), the power supply protection circuit controls V1 to quickly shut down the output, and the voltage drops from Vcc to 0V.

[0040] Figure 7 : When the reference negative power supply is restored midway (yellow voltage waveform, the voltage changes from 0V to -6.5V), the power supply protection circuit controls V1 to connect to the Vcc output, and the output voltage changes from 0V to V㏄ (green output voltage waveform).

[0041] It can be concluded that: during the power-on process, after the reference negative power supply is basically loaded, the drain voltage of the GaN power tube is turned on; during the power-off process, the drain voltage of the GaN power tube is turned off before the reference negative power supply, thereby ensuring the power supply safety of the GaN power tube. When the reference negative power supply is powered off midway, the drain voltage of the GaN power tube is quickly turned off. When the reference negative power supply resumes output, the drain voltage of the GaN power tube resumes power supply with a lag, which is consistent with the power-on process. Therefore, this safety power supply circuit can ensure the power supply safety of the GaN power tube throughout the process.

[0042] The negative bias voltage is used to control the conduction of the field effect switch tube through a diode and an NPN transistor, thereby controlling the power supply voltage to be loaded on the drain of the GaN power tube. When the negative bias voltage is lower than the threshold value, the gate bias of the GaN power tube can ensure that the static current of the power tube reaches the set value. At this time, the negative bias voltage controls the field effect switch tube through a diode and an NPN transistor to connect the power supply to the drain of the GaN power tube, ensuring the power supply safety of the GaN power tube in the three states of "power on", "power off" and "reference negative bias voltage failure".

[0043] The invention provides a safe power supply circuit for a gallium nitride power tube, which is universal and suitable for safe power supply circuits of a full range of GaN power tubes within the range of 20V to 50V, and only requires changing the design parameters according to the third key point.

[0044] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A safe power supply circuit for a gallium nitride power tube, characterized in that: It includes a field effect switch V1, a transistor V2, a diode V3, a resistor R1, a resistor R2, a resistor R3 and a resistor R4, wherein the emitter of the transistor V2 is connected to a reference negative power supply -Vs for supplying a gate bias of a GaN power tube, the base of the transistor V2 is connected to the positive electrode of the diode V3 through the resistor R1, the negative electrode of the diode V3 is grounded, one end of the resistor R2 is connected to the base of the transistor V2, and the other end is connected to the emitter of the transistor V2, and the collector of the transistor V2 is connected to a power supply Vcc for supplying a drain voltage of the GaN power tube through the resistors R3 and R4; The reverse conduction voltage Vr of the diode V3 is configured as Vr≤-(-Vs+0.7+VR1), where VR1 is the voltage drop across the resistor R1; The gate of the field effect switch V1 is connected to the connection point of the resistors R3 and R4, the source of the field effect switch V1 is connected to the power supply Vcc that supplies the drain voltage of the GaN power tube, and the drain of the field effect tube V1 serves as the output end of the circuit and is connected to the drain circuit of the protected GaN power tube.

2. The safe power supply circuit of a gallium nitride power tube according to claim 1, characterized in that: The field effect switch V1 is configured as a P-channel metal oxide field effect transistor.

3. The safe power supply circuit of a gallium nitride power tube according to claim 1, characterized in that: The values ​​of the resistor R3 and the resistor R4 ensure that the voltage between the gate and the source when the field effect switch tube V1 is turned on is controlled between 8 and 11V, and the current passing through the resistor R3 and the resistor R4 is in the milliampere level.

4. The safe power supply circuit of a gallium nitride power tube according to claim 1, characterized in that: The transistor V2 is an NPN transistor.

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