Noise Figure Formulas of RF MOSFETs in the Presence of Digital Substrate Noise

Noise figure (NF) formulas are presented for RF MOSFETs in the presence of digital substrate noise. When the digital substrate noise is much higher than the intrinsic MOSFET noise, simplified NF formulas can be obtained. For the case of which the digital substrate noise is comparable to the MOSFET thermal noise in magnitude, general NF expressions of RF MOSFETs with digital substrate noise are derived. Comparisons of the derived NF formulas and the experimental results are done showing good agreement between them for RF MOSFETs with digital substrate noise.