Computer-aided bipolar transistor model. I - Development of model

A physically-oriented electrical model for the bipolar transistor has been described. It is a nonlinear model and requires eighteen parameters to describe the behaviour of the transistor in all its four modes of operation, i.e. active, cutoff, saturation and reverse region. The eighteen parameters are emitter, base and collector bulk resistances, forward and reverse beta, saturation current, Early voltage, emitter and collector zero-bias junction capacitances, emitter and collector gradient factor and barrier potentials, forward and reverse transit time and constants related to the variations of forward beta with collector current. In effect, it is a modified version of classical Ebers-Moll model which includes effects such as charge storage and basewidth modulation among others and is fully compatible with the standard network analysis programmes. The significant features of the model are that the parameters can be easily determined and systematic modifications in model complexity can be affected.