Study on high power microwave nonlinear effects and degradation characteristics of C-band low noise amplifier

Abstract

High power microwaves (HPM) coupled through the front door pose a potential threat to RF front ends, especially for low noise amplifiers (LNA). Therefore, A C-band LNA circuit model is constructed to investigate the non-linear effects and degradation characteristics of the LNA under HPM, and validate it against damaged samples analysis acquired in HPM injection experiment of LNA. The circuit model consists of a pseudocrystalline high electron mobility transistors (pHEMT) device equivalent physical model and other passive device SPICE models. The nonlinear relationship of input and output signals and the distribution of physical parameters of pHEMT device are analyzed by simulation. When the LNA injection power is less than a certain threshold, the nonlinear degradation of LNA is recoverable. However, when the LNA injection power is greater than a certain threshold, the pHEMT device in the circuit will be damaged by combustion. Under the influence of HPM, it forms a high current channel between gate and channel due to the avalanche breakdown of the Schottky junction and generates a hot spot on the side below the gate near the source, which will eventually cause burnout damage. Moreover, an empirical formula is presented to describe the relationship between the damage time of HPM and the injection power and energy. By scanning electron microscope (SEM) observation and energy dispersive spectrometer (EDS) analysis of the damaged samples, the results show that the pHEMT gate is vulnerable to HPM damage. The hot spot inside the pHEMT device in the simulation is consistent with the damage location of the LNA in HPM injection experiment.