A Q Band MMIC Low Noise Amplifier Design Using 100 nm Gate Length GaAs pHEMT Technology

This paper presents a broadband 30-50 GHz Monolithic Microwave Integrated Circuit (MMIC) Low Noise Amplifier (LNA) designed using WIN Semiconductor's GaAs pHEMT PP10-20 process. The proposed four-stage common-source LNA achieves a average gain of 27 dB and a noise figure below 2 dB across 80 % of the bandwidth at room temperature, with input return loss (S₁₁) below - 10 dB in 60 % of the bandwidth and output return loss (S₂₂) below -10 dB across the entire frequency range. The total DC power consumption is 110 mW. At an operating temperature of 77 K, the LNA demonstrates a slight reduction in gain but maintains good impedance matching and significantly lower DC power consumption of 21.4 mW. These results highlight the potential of this MMIC LNA for cryogenic applications such as radio astronomy. Future work will focus on characterizing its noise performance at lower cryogenic temperatures.