A 0.4-2 GHz MMIC LNA with Integrated Limiter

Recent Earth Observation (EO) missions like SMOS (for Soil Moisture and Ocean Salinity) have revealed that Radio Frequency Interference (RFI) sources in L-band are widespread on the surface of the Earth and can affect the scientific return of future missions. If the RFI signals are strong enough they can also cause irreversible damage to the onboard instrumentation. To prevent this, we need front-end receivers and, consequently, first-stage low noise amplifiers (LNAs) that are robust against damage from strong RFI. This paper presents the design and test results of a robust L-band MMIC LNA operating from 0.4 to 2 GHz and using a space-qualified 150 nm GaN-on-SiC semiconductor process. The LNA employs a cascode architecture and achieves a small-signal gain of 20 dB with a worst-case noise figure of 1.25 dB. The LNA was tested for robustness against strong RFI, demonstrating that it can withstand up to +37 dBm of input power thanks to the use of a novel on-chip limiter co-designed and integrated with the LNA. The maximum input power rating of this LNA is believed to be the highest ever reported in L-band.