Our professor in college was making us understand the stiff voltage-divider bias concept of a BJT.
(Ignore the resistor and voltage source values) Here he says, "The voltage-divider can be called/assumed a "stiff" divider if the current through R1 and R2 is quite large compared to the current going into the base (which makes sense ofc). Such an assumption can be made if the resistance seen looking into the base is much larger compared to (R1+R2), which ensures very less current flowing into the base". How do we measure this resistance looking into the base at bias conditions? I can understand and calculate small signal impedances no sweat, but this confused me idk why. Or for that matter, how would we calculate the impedance looking into any of the terminals at DC? Any kind of hint will help. Thanks!