Q. A transistor in a fixed bias amplifier circuit was replaced by another transistor of beta equaling 150 instead of 60.if IB of transistor is equal to 100 microampere and collector saturation current was 10 mill ampere. Find the new operating point. Even though the transistor is changed, the base current remains the same that is 100 microampere.
The collector current becomes
IC=B*IB = 150*100E-6=15 mA
The collector saturation current was 10mA.This would be same even if the transistor is replaced. But the calculated current IC is seen to be greater than IC(Sat).Hence the transistor is now in saturation. So the operating point can be specified as
IC = IC(SAT) = 10mA
VCE = 0V