Question

From the base bias to the collector feedback configuration, the stability facto S reduces by a factor of __________

(a) 1 + R1/(R1 + β)

(b) 1 + β * R1/(R1 + β)

(c) β * R1/(R1 + β)

(d) R1/(R1 + β)

I had been asked this question in final exam.

My question comes from Collector Feedback Configuration topic in portion Transistor Biasing and Low Frequencies of Analog Circuits

Answer 1

The correct answer is (b) 1 + β * R1/(R1 + β)

To explain I would say: This can be simply observed from the stability factors of both cases. The correct factor is 1 + β * R1/(R1 + β).