I'm essentially trying to obtain Vo/Vs for a NPN-PNP amplifier. I have obtained Vo. I'm trying to get an equation for Vs in terms of Vpi1 essentially. I have tried various techniques from applying a test voltage after rpi1 and obtaining the resistance seen from there to nodal analysis, and I'm always left with at least on new introduced variable.
What should I try?
What should I try?