Question

For the voltage divider circuit, if a diode is connected in reverse direction across the base Find the value of β? (Vd=1.2v and input is 1V)

(a) 0

(b) 50

(c) 100

(d) cannot be determined

This question was addressed to me in semester exam.

Question is from The Operating Point topic in division Transistor Biasing and Thermal Stabilization of Electronic Devices & Circuits

Answer 1

Right answer is (d) cannot be determined

Explanation: Since the input voltage is less than the diode voltage, transistor never turns on during the positive half cycle, hence it is difficult to measure the β value. Also during a negative half cycle, the diode will be turned off and hence no current flows, so the value if beta cannot be determined, it can be 0 because the manufacturer will certainly provide the value.