Modeling of large signal device/circuit interactions

The feasibility of using a physically based research algorithm to generate the coefficients for a nonlinear, equivalent-circuit model of an FET is demonstrated. The coefficients of the ordinary differential equations (ODES) representing the device are determined numerically using a model based on the drift and diffusion equations. The resulting ODE representation is then executed, and the validity of the results are verified, at select bias points, by performing accurate transient drift and diffusion simulations for steady AC operation into a simple resistive load. The comparison gives some degree of confidence in the equivalent-circuit model. However, it is stressed that the equivalent-circuit results must always be regarded as preliminary. It is always necessary to verify them against physical models and against experiments.<>