A NEW CHARGE-CONTROL MODEL FOR SINGLE-HETEROJUNCTION AND DOUBLE-HETEROJUNCTION BIPOLAR-TRANSISTORS

A new charge-control relation is derived for heterojunction bipolar transistors. The relation is valid for arbitrary doping density profiles and for all levels of injection in the base. It is applicable to both single- and double-heterojunction transistors. The model is an improvement over another recently proposed charge-control model that was valid only for constant doping density and low injection in the base. Large-and small-signal equivalent circuit models are also presented for heterojunction bipolar transistors. Comparisons with numerical and experimental data show excellent agreements.