A bipolar transistor model of quasi-saturation for use in computer aided design (CAD)

A bipolar junction transistor (BJT) model containing quasi-saturation behavior has been developed and implemented in a circuit simulation program (SPICE). The model was constructed by modifying and extending the Gummel-Poon BJT model(1)to include the following: 1) Collector resistance conductivity modulation, 2) Collector region recombina tion base current, 3) Collector region charge injection and storage, 4) Collector stored charge differential capacitance. These have been formulated as a function of both the internal junction voltages. The output characteristics, the gain characteristics and the switching behavior are compared to experimental measurements.