Robustness of GaAs and GaN LNAs in X- and Ku- bands: performances and strategies of protection under jamming or destructive signal

Low-noise amplifiers (LNAs) constitute the most vulnerable elements of RF receivers when exposed to high-power in-band signals originating from transmitter leakage, unintentional jamming, or intentional electromagnetic attacks. Conventional receiver architectures generally rely on GaAs LNAs with external protection devices, such as diode limiters, whose insertion losses significantly degrade the overall receiver noise figure. This work investigates alternative hardening strategies based on both GaAs and GaN MMIC technologies operating in X- and Ku-bands. Three protection approaches are experimentally evaluated under dedicated RF step-stress sequences performed at room temperature: i) a cold GaAs LNA (which needs to be associated with an external protection function), ii) a robust GaN LNA exploiting first-stage gain compression to limit power propagation toward subsequent stages, and iii) a self-reconfigurable GaN LNA capable of switching from low-noise operation to protection mode when a critical RF level is detected. Electrical, dynamic, and noise performances are monitored before, during, and after RF stress through measurements of S-parameters, noise figure, gain compression, drain and gate currents, and recovery behavior. The results demonstrate that the GaAs solution preserves excellent low-noise performance but requires a protection device whose insertion loss directly penalizes the receiver noise figure. In contrast, GaN-based solutions withstand substantially higher RF aggression levels, reaching 35-38 dBm input power. The compression-based GaN architecture exhibits survivability up to 38 dBm, while the self-reconfigurable approach maintains low-noise operation under nominal conditions and tolerates RF stress levels exceeding 30 dBm before failure. Moreover, partial recovery of electrical and noise performances after severe stress suggests that charge trapping mechanisms contribute significantly to the observed degradation for the compression-based GaN architecture. This work provides a comparative assessment of receiver hardening strategies using noise figure, dynamic electrical signatures, and RF survivability as common figures of merit. The results highlight the potential of wide-bandgap GaN technologies for the realization of intrinsically robust low-noise receivers with reduced dependence on external protection circuitry.