Mechanisms of Degradation and Damage in GaAs PHEMT Low-Noise Amplifier Under Ultra-Short Microwave Pulses.

Ultra-short microwave pulses with durations of 1 ns or less can go through a PIN limiter with low attenuation before the limiter responds and can therefore be directly injected into the subsequent low-noise amplifier (LNA). Based on this consideration, this paper reports the first investigation of degradation and damage in the GaAs pseudomorphic high-electron-mobility transistors (pHEMT) LNA induced by high-power ultra-short microwave pulses. The effects of pulse power, frequency, and repetition rate on the degradation and damage mechanisms of the LNA are investigated. The results show that, when exposed to a 45 dBm ultra-short microwave pulse at 2 GHz, the region beneath the transistor gate on the drain side experiences the most rapid burnout within 43 ns at a repetition rate of 200 MHz. Further analysis reveals that the negative half-cycle of the high-power microwave pulse depletes the electron concentration in the transistor. Consequently, excessively high repetition rates of high-power ultra-short microwave pulses are less likely to induce transistor burnout. Furthermore, the gain of the LNA is affected by both the electron concentration and the electron mobility in the transistor. The injected high-power ultra-short microwave pulses disturb the electron concentration, while the temperature rise reduces electron mobility. As a result, the transistor performance degrades, leading to a decrease in the LNA gain.