The figure shown below represents two equivalent small signal models of a BJT. The first figure is voltage controlled current source representation and the second figure is the current controlled current source representation. If both the models were constructed for the same transistor, then the value of a is ________

1.20

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1.42

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0.98

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0.78

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Solution

The correct option is C 0.98
From figure, the equivalent current sources can be written as,
$i_{c} = 0.01 V_{b e} = a i_{0}$

$\Rightarrow i_{0} = \frac{V_{b e}}{r_{e}}; r_{o} = 98 Ω$

So, $α (\frac{V_{b e}}{r_{e}}) = 0.01 V_{b e}$

$α = (0.01) r_{e} = 0.98$

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The correct option is C 0.98From figure, the equivalent current sources can be written as, ic=0.01Vbe=ai0 ⇒i0=Vbere;ro=98Ω So, α(Vbere)=0.01Vbe α=(0.01)re=0.98

The correct option is C 0.98
From figure, the equivalent current sources can be written as,
$i_{c} = 0.01 V_{b e} = a i_{0}$

$\Rightarrow i_{0} = \frac{V_{b e}}{r_{e}}; r_{o} = 98 Ω$

So, $α (\frac{V_{b e}}{r_{e}}) = 0.01 V_{b e}$

$α = (0.01) r_{e} = 0.98$