References

Books

1. Ian Getreu, Modeling the Bipolar Transistor, Tektronix, Inc., 1976. (This is the essential, classic text. It has a dedicated chapter on extracting parameters like $VAF$, $RC$, and $RE$ directly from the output characteristics.)

2. S. M. Sze and Kwok K. Ng, Physics of Semiconductor Devices, 3rd ed., Wiley, 2006. (Provides the detailed physics behind the Early effect (base-width modulation) and the behavior of the transistor in the saturation region.)

3. G. Massobrio and P. Antognetti, Semiconductor Device Modeling with SPICE, 2nd ed., McGraw-Hill, 1993. (Details the SPICE model equations for $VAF$, $RC$, and $RE$ and explains how they create the shape of the output curves, particularly the slope in the active region and the 'knee' of the saturation region.)

Video Lectures

• BJT Output Characteristics
• BJT- Early Effect (Base Width Modulation)
• Transistor Saturation