The GATE Grind

GATE 2026 EC – Question 18

Analog Circuits · BJT and MOSFET Amplifiers · 1 mark · Multiple choice

Consider the circuit shown in the Figure with $V_i = 3$ V and $V_{CC} = 12$ V. Assume $V_{BE}=0.7$ V and $\beta_{dc}=99$ for the BJT. Which of the following options is the correct value of the current $I_o$?

Diagram for GATE 2026 EC question 18
  1. 60 μA
  2. 6 μA
  3. 3 μA
  4. 30 μA

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Correct answer: (D) 30 μA

Explanation

The op-amp forces the emitter voltage to 3 V, so $I_E=3\text{ V}/1\text{ k}\Omega=3$ mA. Then $I_o=I_B=I_E/(\beta+1)=3\text{ mA}/100=30\ \mu$A.