摘要： Electromagnetic pulse (EMP)-induced nonlinear degradation of an L-band gallium arsenide-based low-noise amplifier (LNA) is studied by an injection experiment, failure analysis, and mixed-mode simulation. The experimental results indicate that the real-time response, radio frequency, and direct current characteristic of LNA samples under an EMP show nonlinear and permanent degradation features. In detail, the characteristics first degrade and then recover slightly as the injection power increases. In addition, the nonlinear degradation shows a close dependence on the pulse properties. Failure analysis reveals that the degradation of the LNA is attributed to latent failure defects under and around the gate metal strip of the first-stage high electron mobility transistor, with recovery well interpreted by an EMP-induced 'annealing effect.' Simulation results show that if the pulse repetition frequency is smaller than 2.5 kHz, a pulse repetition-induced thermal accumulation effect will not occur and that the pulsewidth τ will mainly determine the actual action duration and the temperature of the 'annealing effect.' Based on the above mechanism, the dependence of the pulse properties on nonlinear degradation is well explained.