Question

Comparing fixed and collector to base bias which of the following statement is true?

(a) Fixed bias is more stable

(b) Collector to base bias is more stable

(c) Both are the same in terms of stability

(d) Depends on the design

I have been asked this question during an interview for a job.

Question is from Bias Stability in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

Answer 1

Right choice is (b) Collector to base bias is more stable

The best I can explain: For fixed bias circuit, S = 1+beta, more the beta, lesser the stability

For collector to base bias S = (1+beta)/(1+beta(RC/RC+RB))

Hence collector to base bias is more stable.