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Question 17.PE.MCQ.22: For the transistor discussed in Question 21, what is the b-c......

For the transistor discussed in Question 21, what is the β-cut-off frequency and the value of commonemitter short circuit gain at that frequency?

(a) 358.63 kHz, 158.39 ∠−45°

(b) 358.63 kHz, 158.39 ∠45°

(c) 237.53 kHz, 126.78 ∠45°

(d) 237.53 kHz, 126.78 ∠−45°

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(b) From the solution of Question 21, f_β = 358.63  KH_Z

For  f=f_{\beta}

A_{\mathrm{i}}=-{\frac{224}{1+j\left\{\left(358.63\times10^{3}\right)/\left(358.63\times10^{3}\right)\right\} }}=-\,{\frac{224}{1+j}}

|A_{\mathrm{i}}|={\frac{224}{\sqrt{2}}}=158.39

Therefore,

\angle A_{\mathrm{i}}=90^{\circ}-{\mathrm{tan}}^{-1}(1)=90^{\circ}-45^{\circ}=45^{\circ}

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