GATE 2016 EC (EC3) – Question 24
For the circuit shown, assume $V_{BE1}=V_{EB2}=0.7$ V. The dc collector voltage $V_{C2}$ in volts is ________.
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Correct answer: 0.45 to 0.55
Explanation
Q1's base and collector are tied to 2.5 V, so its emitter, which drives Q2's emitter, is 2.5−0.7=1.8 V.
Q2 is PNP, so its base is 1.8−0.7=1.1 V. Its 10 kΩ base resistor connects to a 1 V source, giving base-current magnitude $(1.1-1)/10000=10$ μA.
With β2=50, its collector current is 0.5 mA. The 1 kΩ collector resistor therefore gives **$V_{C2}=0.5$ V**.