Transistor Modeling using Advanced Circuit Simulator Technology

Abstract

The advanced MOSFET model based on the Berkeley Short Channel IGFET Model (BSIM) version 4 is implemented in the circuit simulator Transim. The model is implemented as a charge controlled model using object-oriented programming and automatic differentiation. The result is a dramatically simplified approach to implementing the BSIM4 model in a simulator. The modeling technique does not use the associated discrete modeling approach commonly used in circuit simulators with the result that off-the-shelf numerical solvers can be used. The model is a simulator independent model and the same model code can be used for DC, transient and harmonic balance analysis. Implementation of the model was completed in 7 months with 17 pages of C++ code compared to the original code for the model implemented in SPICE that was 200 pages long. Results for an NMOS circuit are presented for DC and transient analysis.