Variation in RF Performance of MOSFETs Due to Substrate Digital Noise Coupling

In this letter, the variation in the key RF performance parameters of MOSFETs in the presence of the substrate digital noise coupling is investigated. The parameters, including f_T and f_max, showed substantial change up to ~20% with realistic level of noise injection. It is shown that such change in the RF performance with the noise injection is due to the threshold voltage ( V_T) variation. The observed V_T variation is attributed to the virtual body effect due to the substrate potential fluctuation by the coupled substrate digital noise.