Question

How is BJT used as a faster switch?

(a) By operating it in the saturation and cut-off region

(b) By operating it in the active and cut-off region

(c) By using it in strong saturation

(d) By decreasing its ON resistance

I got this question in an online quiz.

Question is taken from Transistor Switching Network in division Transistor Biasing and Low Frequencies of Analog Circuits

Answer 1

Right choice is (b) By operating it in the active and cut-off region

The explanation is: If BJT is to act as a switch with negligible power dissipation, then BJT is operated in the cut-off and saturation region, as in the TTL family. When BJT has to be operated as a fast switch, then it is operated in the active and cut-off region, as in the ECL family.