A new RF model for the accumulation-mode MOS varactor

This paper presents a new RF model of an accumulation-mode MOS varactor, which is composed of the physically meaningful parameters. This model can describe the characteristics of the device with simple equations valid in all operating regions. For easy integration into common circuit simulators, a single topology with the lumped elements derived from the device structure has been proposed. With directly extracted parameters based on the Z-parameter analysis on the equivalent circuit, excellent agreements between measured data and simulation results were obtained without any optimization steps in the frequency range up to 18 GHz, as well as the overall bias range.