A PHYSICS-BASED HBT SPICE MODEL FOR LARGE-SIGNAL APPLICATIONS

A new, physics-based, large-signal SPICE model for graded-base HBT's i s reported. The novelty of the model lies in its use of the emitter-ba se diode ideality factor to account for the voltage dependencies of th e tunnelling factor and the barrier height for back injection of elect rons. This expedient allows the HBT to be simply represented in SPICE by the regular homojunction BJT macromodule of this stimulator. The us efulness and accuracy of the model are demonstrated by comparisons of simulated and measured data for a graded-base AlGaAs/GaAs HBT: dc I-V data and large-signal switching results from a ring-oscillator circuit are presented.