Electronic Devices - Dec 2014

Electronics Engineering (Semester 3)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks. 1 (a) For the diodes, define forward voltage drop, maximum forward current, dynamic resistance, reverse saturation current & reverse breakdown voltage,(5 marks) 1 (b) Draw characteristics of Pn junction in thermal equilibrium? Explain.(5 marks) 1 (c) Define the contributing factors forwards the low frequency common base current gain of BJT.(5 marks) 1 (d) Define internal pinch-off voltage, pinchoff voltage J& drain to source saturation voltage of JFET.(5 marks) 1 (e) What are types of MOSFET? Explain.(5 marks) 1 (f) Explain construction working & characteristics of UJT.(5 marks) 2 (a) What is space charge width? Derive an expression for it, when the diode is forward biased and reverse biased.(10 marks) 2 (b) List the ideal conditions of BJT and explain the non-ideal effects.(10 marks) 3 (a) Draw Ebers-Moll equivalent circuit of BJT & derive necessary expressions for current and voltages.(10 marks) 3 (b) Compare BJT, JFET & MESFET.(10 marks) 4 (a) What is channel length modulation in MOSFET? Derive necessary expression for the same.(10 marks) 4 (b) Explain construction working & characteristics of Tunnel diode.(10 marks) 5 (a) What is HBT? Explain construction & energy band diagram of the same.(10 marks) 5 (b) For an n-channel MOS transistor with ?n=600 cm²/vs, C_ox=7\times 10^{-8} F/cm², W=20 ?m, L=2 ?m and V_TO=1.0V Examine the relationship between the drain current & terminal voltages.(10 marks)

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6 (a) SCR(5 marks) 6 (b) Solar Cell(5 marks) 6 (c) Photo diode(5 marks) 6 (d) IGBT(5 marks)