Estimation of MOSFET Channel Noise and Noise Performance of CMOS LNAs at Cryogenic Temperatures

The design of cryogenic CMOS electronics for quantum computing applications, including critical radio frequency blocks such as low noise amplifiers (LNAs), is hindered by the lack of mature RF and noise models for cryo-MOSFETs. In this paper, we study the temperature scaling trends of important MOSFET RF parameters and evaluate the noise performance of commonly-used LNAs at cryogenic temperatures. We show that traditional thermal-noise-based models significantly underestimate the noise of cryo-CMOS LNAs. Instead, we employ a shot-noise-based model that is relatively temperature independent to predict noise factors of cryo-CMOS LNAs, which are consistent with published experimental results. We provide analyses and guidelines to further improve their noise performance to meet requirements of future QC applications.