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Question No. 39 ECE | GATE 2017

In the figure shown, the npn transistor acts as a switch.

For the input Vin(t) as shown in figure, the transistor switches between the cut-off and saturation regions of operation, when T is large. Assume collector-to-emitter voltage at saturation VCE(sat)=0.2V and base-to-emitter voltage VBE(sat)=0.7V. The minimum value of the common-base current gain($\alpha$) of the transistor for the switching should be___________.

Answer : 0.89 to 0.91

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