CN-121984455-A - Time domain modulation protection circuit suitable for GaN power amplifier

CN121984455ACN 121984455 ACN121984455 ACN 121984455ACN-121984455-A

Abstract

The invention discloses a time domain modulation protection circuit suitable for a GaN power amplifier, which comprises a negative voltage clamping circuit and a switching circuit. The TTL receiving end of the negative pressure clamping circuit is connected with an external control signal, and the switching circuit is controlled by the TTL signal to realize the switching/pulse modulation of the drain voltage of the power amplifier. When the negative pressure power supply fails, the negative pressure clamping circuit controls the switching circuit to be turned off rapidly, and the power amplifier has no leakage voltage input, so that the power amplifier is prevented from being damaged. The invention realizes the time domain modulation of the drain voltage of the power amplifier, and performs power-off treatment on the power amplifier when the negative-pressure power supply fails, thereby avoiding the damage of the power amplifier. Meanwhile, the invention has the advantages of simple and efficient design and high response speed.

Inventors

HE JING
CAI YAO
LU CHENGYI
LI JIANG
Luo Hulei
YANG FENGLIN
ZHANG BIN

Assignees

航天恒星科技有限公司

Dates

Publication Date: 20260505
Application Date: 20251231

Claims (8)

1. The time domain modulation protection circuit suitable for the GaN power amplifier is characterized by comprising a negative voltage clamping circuit and a switching circuit; the negative pressure input end of the negative pressure clamping circuit is respectively connected with a negative pressure power supply and the grid electrode of the GaN power amplifier, the output end of the negative pressure clamping circuit is connected with the control end of the switch circuit, and the TTL input end of the negative pressure clamping circuit is connected with an external control signal; The positive voltage input end of the switching circuit is connected with the positive voltage power supply, and the positive voltage output end of the switching circuit is connected with the drain electrode of the GaN power amplifier to supply power to the GaN power amplifier.
2. The time domain modulation protection circuit for the GaN power amplifier according to claim 1 is characterized in that when a TTL input end of the negative pressure clamping circuit receives a TTL pulse signal, the negative pressure clamping circuit controls the switching circuit to output a positive voltage which is turned on-off along with the pulse frequency, the GaN power amplifier works in a continuous wave or pulse mode through leakage adjustment, and when a negative pressure power supply fails, the negative pressure clamping circuit controls the switching circuit to be turned off, the switching circuit outputs 0V, a power amplification source is turned off, and damage to the GaN power amplifier is avoided.
3. The time domain modulation protection circuit for a GaN power amplifier according to claim 1, wherein the negative voltage clamp circuit comprises a triode U1, a zener diode N1, a resistor R3, and a resistor R4; The base of the triode U1 is respectively connected with the positive electrode of the voltage stabilizing diode and one end of the resistor R4, the emitter of the triode U1 is respectively connected with the other end of the resistor R4, the negative pressure power supply and the grid electrode of the GaN power amplifier, the collector of the triode U1 is used as the output end of the negative pressure clamping circuit, the negative electrode of the voltage stabilizing diode is connected with one end of the resistor R3, and the other end of the resistor R3 is used as the TTL input end of the negative pressure clamping circuit.
4. A time domain modulation protection circuit for a GaN power amplifier according to claim 3, wherein said switching circuit comprises a capacitor C1, a resistor R2, and a MOS transistor U2; the source electrode of the MOS tube U2 is respectively connected with a positive-voltage power supply, one end of the capacitor C1 and one end of the resistor R1, the drain electrode of the MOS tube U2 is connected with the drain electrode of the GaN power amplifier, the grid electrode of the MOS tube U2 is respectively connected with the other end of the capacitor C1, the other end of the resistor R1 and one end of the resistor R2, and the other end of the resistor R2 is used as a control end of the switch circuit.
5. The time domain modulation protection circuit for a GaN power amplifier according to claim 4, wherein when the negative-pressure power supply works normally, the triode U1 is switched on and off along with a control signal input by the TTL input end, so as to control the MOS tube U2 to be switched on or off, and the GaN power amplifier works in a pulse mode.
6. The time domain modulation protection circuit for GaN power amplifier according to claim 5, wherein when the negative voltage power supply is operating normally, when the control signal is low, the transistor U1 is turned off, the output end of the negative voltage clamping circuit is suspended, the gate voltage U GS of the MOS transistor U2 is 0, which is smaller than the turn-on voltage U GSth of the MOS transistor U2.
7. The time domain modulation protection circuit for GaN power amplifier according to claim 5, wherein when the negative voltage power supply is in normal operation, when the control signal is at high level, the transistor U1 is turned on, and the gate voltage of the MOS transistor U2 is The method comprises the following steps: Wherein U D is positive supply voltage, U dd is TTL input terminal voltage, U gg is negative supply voltage, The collector current of the triode U1 when the triode is conducted; setting the resistance values of the resistor R1 and the resistor R2 to enable the grid voltage of the MOS tube U2 Is larger than the conduction voltage U GSth of the MOS tube U2, and the MOS tube U2 is conducted.
8. The time domain modulation protection circuit for GaN power amplifier according to claim 4, wherein when negative voltage power failure occurs, base current of triode U1 is 0, base emitter voltage of triode U1 is smaller than on voltage, triode U1 is turned off, gate voltage of MOS tube U2 is 0, MOS tube U2 is turned off, and GaN power amplifier is turned off.

Description

Time domain modulation protection circuit suitable for GaN power amplifier Technical Field The invention relates to a time domain modulation protection circuit suitable for a GaN power amplifier, and belongs to the technical field of radio frequency transmitters. Background The power amplifier (hereinafter referred to as power amplifier) is an important component of radio frequency transmitting equipment, and is widely applied to the fields of radar, satellite communication and the like. In general, the power amplifier includes electrodes such as a gate and a drain, and also includes rf input and output ports. When proper voltage is added on the grid electrode and the drain electrode of the power amplifier, the power amplifier amplifies and outputs the radio frequency signal at the input end of the power amplifier to a certain extent. Most power amplifiers operate in continuous wave mode, but in practical applications such as radar transmitters, it is desirable to operate in pulsed mode. Therefore, a suitable circuit is needed to enable the power amplifier to operate in a pulsed mode. In addition, due to the characteristics of part of the power amplifier, in order to avoid being burnt by instantaneous high current during power-up, grid voltage (negative pressure) needs to be added first and then drain voltage needs to be added on the power-up time sequence, and the power amplifier has no related protection circuit. Therefore, a time domain modulation protection circuit with modulation function, which is simple, efficient and low-cost, is urgently needed in modern PCB design. Chinese patent CN215646734U proposes a negative voltage protection circuit, which includes devices such as an operational amplifier, a resistor, a triode, a MOS transistor, etc. The high-low level generated by the comparator formed by the operational amplifier is used for controlling the on and off of the MOS tube, so that the negative pressure protection function can be effectively realized. However, the power amplifier has no pulse modulation function, the circuit response speed is low, and the power amplifier cannot be rapidly cut off when negative pressure fails. Meanwhile, the circuit has complex structural design, uses more than 5 main devices, and cannot meet the requirements of miniaturization and low cost of the PCB design. In the background of the increasingly high degree of integration and miniaturization of circuit designs, the application range of the circuit is greatly limited. Chinese patent CN110224633a proposes a negative-pressure bias circuit and protection method for a power amplifier, the circuit comprising a negative-pressure generating module, a negative-pressure monitoring module, a logic control unit and a switch. The negative pressure monitoring module collects negative pressure and compares the negative pressure with a threshold value, a comparison result is sent to a logic control unit (such as CPLD or MCU) to judge, and the logic control unit outputs a signal to control the on-off of the switch unit so as to realize protection. The patent adopts a digital control architecture of detection-logic-execution, uses more than 7 components including MCU, is more complex in design, and is unfavorable for the miniaturization design of equipment. Meanwhile, the circuit is also required to write different software programs according to different requirements, and has no universality in circuit generalized design. Further, since a digital circuit is used, the cost is high, and the economy is not achieved. Chinese patent CN116505888a proposes a negative voltage protection circuit of a GaN power amplifier, in which a linear voltage regulator is mainly responsible for providing stable negative voltage bias for a gate, a first switching tube is mainly used for controlling whether the amplifier obtains a working voltage, a driver is mainly used for driving and controlling on and off of the first switching tube, and second and third switching tubes and resistors are mainly used for monitoring the state of negative voltage of the gate and outputting a control signal to an input end of the driver to finally determine on-off of the first switching tube. The circuit is complex in composition, all modules belong to a single series model, the whole function is invalid under the condition that a circuit part is invalid, and the circuit does not have a voltage modulation function and cannot modulate the drain voltage of the power amplifier, so that the circuit is not suitable for the use requirements of most pulse power amplifiers. In summary, since the power-on time sequence circuit is not designed in the existing GaN power amplifier, the peripheral power supply circuit cannot provide a fast-response negative pressure protection function, and cannot pulse the power amplifier. Meanwhile, various existing circuits or structures are complex, or have single functions and high cost, and under the trend of increasingly strict requirements