Compact modeling of transient substrate current of MOSFET

Fast switching signals drive MOSFET into non-quasi-static operation, causing significant charging current in both on-state and off-state. Since MOSFET can be worked as a varactor in RF circuits, the modeling in the off-state is important. In this paper, a compact model is developed to model the fast-switching behavior of transistors in both states. Instead of solving the continuity and drift-diffusion equations, the model reduces the distributed network into a lumped circuit model, which is more compatible with the framework of compact model. The proposed model has been implemented in conjunction with the BSIM model and has been shown to be valid from the accumulation to the inversion. The model is developed independently from the existing I-V and C-V models and can be applied to any advanced model besides BSIM.