Claude,
Thanks for your answer. This will help me to double check if I'm right with my approximation. However, there should be another way to get to the intrinsic emitter resistance.
According to the attached picture, the resistance can be approximated with delta Vc and delta Ve (the deltas...
In my circuits class we were talking about bipolar transistors and our prof. mentioned that every bipolar resistor has an intrinsic emitter resistor. So, I tried modeling a couple of circuits in SPICE to see if I can replace the transistor with another circuit (voltage source, current source...