A BJT biasing circuit is shown in the figure, where V BE=0.7 V and =100. The Quiescent Point values of V CE and I C are respectively

GATE 2024 EE – Question 42

Analog and Digital Electronics · Amplifiers: biasing, equivalent circuit and frequency response · 2 marks · Multiple choice

A BJT biasing circuit is shown in the figure, where $V_{BE}=0.7$ V and $\beta=100$. The Quiescent Point values of $V_{CE}$ and $I_C$ are respectively

4.6 V and 2.46 mA
3.5 V and 2.46 mA
2.61 V and 3.13 mA
4.6 V and 3.13 mA

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Correct answer: (A) 4.6 V and 2.46 mA

Explanation

Thevenin equivalent at the base: $V_{th}=12\times\dfrac{50}{150}=4$ V, $R_{th}=100\parallel50=33.3$ kΩ. Then $I_B=\dfrac{4-0.7}{33.3\text{k}+101\times1\text{k}}=24.6\ \mu$A, $I_C=\beta I_B=2.46$ mA and $I_E=2.48$ mA. $V_{CE}=12-2\text{k}\times2.46\text{ mA}-1\text{k}\times2.48\text{ mA}=4.6$ V.