Question

Among the following statements which one is true according to feedback bias?

(a) Fixed bias is more stable than emitter feedback bias

(b) Fixed bias produces more feedback than emitter feedback bias

(c) Emitter feedback bias is more stable than the fixed bias

(d) Fixed and emitter bias have same stability and feedback

I got this question during an internship interview.

The doubt is from Emitter Feedback Bias topic in section Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

Answer 1

The correct choice is (c) Emitter feedback bias is more stable than the fixed bias

Best explanation: Since S is having a linear relationship with beta in fixed bias, it is less stable, but in emitter feedback bias, S is not exactly linear with a beta. In fixed bias, even a small change in ICo changes the IC value very much, but due to negative feedback in emitter bias, ICo  does not change the IC value maintaining its stability.