Duo-diode Models of BJT

The document describes the Ebers-Moll model and Charge-Control model for bipolar junction transistors (BJTs). The Ebers-Moll model treats a BJT as two diodes and defines relationships between the base-emitter, base-collector, and collector currents. However, it cannot account for effects like the Early effect. The Charge-Control model tracks the storage of charges in the normal and inverted regions and defines transit times, improving its accuracy over the Ebers-Moll model.