Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
I forgot to mention that Vs is ignored. Can you tell me that trivial answer? Do we just say that it's equal VCC becuase it's labled VCC?Obviously, the statement is not true, except for Vout = 0. Then the answer is trivial.
for that to be true the xtors must be very close in gain ...
The output KVL applies to -Vcc, Vce(Q2), Vce(Q1), + Vcc. We have:
-Vcc+Vce(Q2)+VC(Q1) = Vcc that is:
Vce(Q1)+Vce(Q2) = 2Vcc
if Vout = 0 we have (set Vout=0 and apply KVL to both lower and upper transistors):
-Vcc+Vce(Q2) = 0 ==> Vce(Q2) = Vcc
and Vce(Q1) = Vcc
This condition can be reached when Vs=0 if the npn and pnp behave exactly the same (as already said by FvM). Under this condition, if Vs <> 0 then
Vce(Q1) <> Vce(Q2) and of course Vce(Q1)+Vce(Q2) = 2Vcc applies.
This means the output voltage can span from -Vcc+Vce(Q2sat) to +Vcc-Vce(Q1sat)