Question

Consider the graph of IC vs VI shown below for a transistor. Find the correct relation for region 3 in the diagram.

(a) IC = IC(sat) and VCE = VCE(sat)

(b) IC = IC(sat) and VCE = VCC

(c) IC = βIB and VCE = VCE(sat)

(d) IC = βIB and VCE = VCC

This question was addressed to me in an interview.

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

Answer 1

Right choice is (a) IC = IC(sat) and VCE = VCE(sat)

For explanation I would say: Region 3 in the above is the saturation region in which IC remains constant with respect to the input voltage and the voltage VCE is the saturation voltage, almost zero. At this point, the transistor acts as an ON switch.