On the high-frequency characteristics of substrate resistance in RF MOSFETs

The high-frequency (HF) behavior of substrate components in MOSFETs is studied at different bias conditions for a 0.35 mum BICMOS technology in the frequency range up to 10 GHz, It was found that the observed strong bias dependence of the real part of admittance y(22), Re{y(22)}, is mainly contributed by the channel conductance. A very weak bias dependence of substrate resistance mas found after deembedding the measured y(22) to remove the influence of channel resistance R-ds and gate-to-drain capacitance C-gd. The results are key to the understanding and modeling of the HF behavior of MOSFET substrate components for RF IC design.