Hi there, I'm having problems in being able to derive this expression - I don't understand why rpi/(rpi+rb) is multiplied by the other expression
Breaking the left part of the circuit down into something that looks like this:
then... using the voltage divider rule
Vout = Vs(rpi+rb||R1||r1)/(rpi+rb||R1||R2 + Rs)
But of course we want the voltage over Rpi.. which is where I'm stuck.
Sorry if this seems trivial...