An RF model of the accumulation-mode MOS varactor valid in both accumulation and depletion regions

Abstract

This brief presents an RF model of an accumulation-mode MOS varactor with physical lumped elements derived from the device structure. The channel resistance was modeled by, three resistance components to cover both accumulation and depletion regions with single equivalent circuit. With parameter values obtained by direct extraction, this model could accurately describe characteristics of the device without any optimization steps in the frequency range up to 18 GHz, as well as over a wide bias range. Due to the single topology, easy integration of the model into common circuit simulators is possible.