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B3C053S Pages: 3

a) Derive the terminal current equations of a npn transistor. List the assumptions made for
the derivation. (12)
b) Define with expressions i) Base transport factor ii) Emitter injection efficiency 111)

Current transfer ratio iv) Base to collector current amplification factor. (8)

OR

. a) Draw and explain the capacitance- voltage characteristics of an n-channel MOS

capacitor. (5)
b) What are the effects of real surfaces on the threshold voltage of a MOS capacitor?
Derive the threshold voltage equation of a real MOS capacitor? (10)
०) Ann’ -polysilicon gate n-channel MOS transistor is made on a p-type Si substrate with
N,= 10%. The 9102 thickness is 100A in the gate region, at the onset of inversion.
Find i) width of depletion layer and ii) Vr. Given & of Si and 5102 are 11.8 and 3.9
respectively. (5)

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