Pulse length dependency of the failure of a low noise amplifier

High Power Microwave (HPM) sources are continuously improving in performance. The low noise amplifier (LNA) is one of the first components in the front-end receiver that will be hit by high power pulses in case of an attack. Destructive testing of ~30 LNAs has been carried out to investigate the pulse length and power dependence of LNA failure due to electrical overstress. It was found that a noticeable increase in the power required to cause destruction of this device occurs when the pulse length falls below ~10 µs. The power levels required to destroy the device with short microwave pulses (> 33 dBm) is rather high compared to the maximum allowed CW power input level specified by the manufacturer (15 dBm). Therefore applying the CW power limitation of the LNA also to pulsed threats may be too strict. Such information should be useful when specifying the hardening of a system against intentional (HMP) or unintentional (RADAR etc.) microwave illumination, that are expected to have short pulse lengths. The measured data was fitted to three different models with good correspondence. However there still exists an uncertainty in how to apply these models to a different device without detailed high power measurements.