Analog Electronics - 1 - May 2014

Electronics & Telecomm. (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.

Solve any five :-

1 (a) Explain effect of temperature on characteristics of PN junction diode.(4 marks) 1 (b) Why LC oscillators are prefered for high frequency applications?(4 marks) 1 (c) Find R_B and R_C for the circuit shown to obtain V_CE=5V and I_C=2mA (4 marks) 1 (d) In n-channel MOSFET V_DS=5V, V_GS=5V, V_BS=0, W=10 ?m, L=5 ?m k'n=100 mA/V₂ and V_TO=1V. Calculate its drain current for channel length modulation factor ? of 0 and 0.25 V^-1(4 marks) 1 (e) Draw and explain small signal hybrid-Pi model of BJT including early effect.(4 marks) 1 (f) Differentiate between NJT and MOSFET(4 marks) 2 (a) Find I_CQ and V_CEQ for the circuit shown in figure 2a if ?=100 (10 marks) 2 (b) Draw and explain energy band diagram of MOS capacitor in accumulation, depletion and inversion region.(10 marks) 3 (a) Draw and explain working of transisterized Wien Bridge Oscillator(10 marks) 3 (b) The JFET shown in figure 3b has parameter I_DSS=8mA and V_p=4V. Determine V_G, I_DSQ, V_GSQ and V_DSQ (10 marks) 4 (a) For the common gate circuit shown in figure 4s, the NMOS transistor parameters are V_TN=1, kn=3 mA/V² and ?=0 (i) Determine I_DSQ and V_DSQ (ii) Calculate gm and ro (iii) Find the small signal voltage gain Av= v₀/v₁. Assume Cc₁ and Cc₂ acts as short circuit for small-signal analysis (10 marks) 4 (b) The parameter of the transistor in the circuit shown in figure 4b are ?=100 and V_A=100V. (i) Determine the voltages at base and emitter terminals (ii) Find Rc such that VCEQ=3.5V and (iii) Assuming CC and CE acts as short circuit determine small signal voltages gain Av= v0/vs (10 marks) 5 (a) Derive expression for voltage gain NMOS source follower cicuit(8 marks) 5 (b) For the common base amplifier shown in figure 5b, derive expression for voltage gain, current gain, input resistance and output resistance using hybrid-? model (12 marks)

Write short note on any three :-

6 (a) Series and shunt clippers(7 marks) 6 (b) Twin-T oscillator(7 marks) 6 (c) MOSFET operation(7 marks) 6 (d) Construction and operation of varactor diode.(7 marks)