This paper discusses the damage characteristics of gallium nitride (GaN)-based low-noise amplifiers (LNA) under high power microwave (HPM) pulses.

The effect of HPM pulses with different pulse widths and duty cycles was studied to investigate the changes in DC and RF parameters of GaN LNA. In the experiment, the threshold power of the device was determined through continuous wave and microwave pulse testing with different pulse widths and duty cycles. At the same time, in order to better determine the damage area and the physical mechanism of LNA failure, the surface and internal areas of the chip were examined using a microscope and dual-beam FIB （focused ion beam ） devices after the chip was unpackaged.

The experimental results show that when the GaN LNA was exposed to sufficient microwave pulse power with a pulse width of 30 ns, a rising edge of 18 ns, and a falling edge of 18 ns with a period of 2 ms, the gain of the LNA decreased from 23.67 dBm to -8.91 dB, the noise factor increases from 1.59 dB to 18.13 dB, and the LNA output waveform was severely compressed. The damage was primarily caused by the formation of a micro-current channel at the gate from HMP exposure, leading to drain overcurrent and permanent device damage.

The study on the damage effects of GaN LNA under HMP pulse conditions provides important reference value for further understanding the impact of HMP pulses on GaN LNA and for improving its robustness.