A charge-based small-signal model for the bipolar junction transistor

Abstract

A small-signal model for the bipolar junction transistor (BJT) is proposed which is derived directly from a very physical charge-based large-signal model. Because the large-signal model accurately accounts for the peripheral and intrinsic transistor current and charge partitions as well as the distributed base resistances and collector-base junction capacitances, the small-signal elements derived from this model accurately reflect the high-frequency and high-current operation of advanced BJTs. d.c. Verification of the large-signal model and preliminary a.c. verification of the small-signal model are achieved through comparisons of simulations and experimental (de-embedded s-parameter) data taken on advanced BJT test structures over a range of operating conditions and emitter areas. Because agreement between the measured and simulated data is good, it is concluded that this model is generally valid for advanced BJT simulation.