A physics-based HBT SPICE model for large-signal applications

A new, physics-based, large-signal SPICE model for graded-base HBT's is reported. The novelty of the model lies in its use of the emitter-base diode ideality factor to account for the voltage dependencies of the tunneling factor and the barrier height for back injection of electrons. This expedient allows the HBT to be simply represented in SPICE by the regular homojunction BJT macromodule of this stimulator. The usefulness 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. >