GATE Electrical Engineering (EE) 2021 Solved Papers

Question : 34 of 65

Marks: +1, -0

In the

{BJT}

circuit shown, beta of the

{PNP}

transistor is Assume

{V}_{ {BE}}=-0.7 {V}

. The voltage across

{R}_{ {C}}

will be

5 {V}

when

{R}_{2}

is _________

{k} Ω

. (Round off to 2 decimal places).

Solution:

R_{2}=\;{V_{B}}/{I_{2}}

I_{c}=\;{5}/{3.3}=1.515 {mA}

I_{B}=\;{I_{C}}/{B}=\;{1.515}/{100} {mA}=0.0151 {mA}

I_{E}=I_{C}+I_{B}=1.530 {mA}

{V}_{ {B}}=12-1.2 {I}_{ {E}}-0.7

I_{2}=I_{1}+I_{B}=\;{12-9.46}/{4.7}+\;{1.515}/{100}=0.55 {mA}

R_{2}=\;{9.46}/{0.550}=17.02 {k} Ω

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