RTU 2016 Question Paper Semester IV Electrical and Electronics Engineering Analog Electronics

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t< B.Tech. IV-Sem (N,Iain & Back)Exam; June_July 2016
+
rII Electrical & Electronics Engineering
+ 4EXIA Analog Electronics
Common with EE, EX, EC, EI

Time: 3 Hours Maximum Marks: 80
Min. Passing Marks (Main & B6rck): 26
Min, Passing Marks (Old Back): 24
v Instructi.ons to Candidates:-

Attempt any five que;tions, selecting one question
from each unit. All
Questions carry equal marks. schematic diagrams must be shown
wherever necessary. Any data you feel missing suitably be
assum'ed and
stated clearly.
units of quantities used"/ calculated must be stated clearly.

use of following supporting material is permitted during examination.

(Mentioned in form No.205)

1. NIL
2. NIL

Q'1 (a) What are the four possible topologies of a feedback amplifier? Explain with neat
skerches.
tgl
(b) Calculate the voltage gain with and without feedback for the given in
figure, with valueS, gm = 5mA/V, Ro = s.lKO, R,
"ir"uit
=.lKO, & = 20Ke.
ra= IMO.
tgl

[4F4L20] Page 1 of4

OR

e.l (a) Sketch the circuit of a current series feed - back amplifier. Obtain the expression
for the voltage gain and the input resistance of this amplifier. t8l

(b) Calculate the voltage gain, input & output resistance of a voltage series feedback
amplifiers having Au= 300, Rr= 1'5KC), Ro= 50KQ and B = 7ll5' t8l

e.2 (a) Sketch the circuit for a wein bridge oscillator. What determines the frequency of
Oscillators? Will oscillations take place if the bridge is balanced? tSl

(b) In a transistor colpitts os'cillator has the following parameters. t8l

L = 100pH, Lnrc = 0.6rnll, Cz = 0'001PF, Cr = 0'01pF, C" = 10pF

l4E4L20) Page2 of4 [1ss6ol

Determine -

(i) Operaringfiequency
(ii) Feedback - fraction
(iii) Minimum gain to sustain oscillations and emitter resistance if R6 = 2.5KO.
OR
Q.2 (a) What is Schmitt triggering? Explain the working of Schmitr trigger with the help
of a neat circuit diagram and waveforms.
t8t
(b) In a astable multi vibrator circuit diagram shown below, R,
= Rz = 5KC),
R: = R+= 0.4Kf) and C1 - C2= 0.02pF.
t8l

+6V

Determine -
(i) Time period and frequency of circuit oscillation.
(ii) Minimum value of transistor B.
UNIT.III
Q.3 (a) Draw neat diagram of hybrid - zt model for a transistor at high frequency in CE
configuration, discuss in brief.
tl0l
(b) In a hybrid zr model, prove that diffusion capacitance at an emitter junction -
Ca" = grnW't pOel where, gm = transistor transconductancei W
= base width;
De = diffusion constant for minority in base region.
t6l

14841201 Page 3 of4

OR
Q.3 (a) Write a short note on Emitter follower at high frequency and drive expression for
high frequency voltage gain. t8l
(b) Given the following transistor measurement at Ic = 5mA' vcB = 10v' and at room
temperature. h1" = 100, h1" = 600ohm, Ai = l0 at 10MHz , CC = 3pF. Find Fs , Ft ,
C" , fb," and f56,. t8l
UNIT-IV
e.4 (a) Draw the parallel resonant circuit. Obtain the expression for its band width and Q
factor. t6l
(b) The single tuned amplifier circuit consists of tuned circuit having R = 50ohms,
L = 10rnH and C = 0.lpF. Determine the t10l
(i) Resonant frequency
(ii) Q factor of the tank circuit and
(iii) BW of the amplifier.
OR
e.4 (a) What is stagger tuned amplifier? Explain its working with help of frequency
response. t8l
(b) Draw and explain the circuit of double tuned amplifier with the help of frequency
response. t8l

e.5 (a) Derive an expression for output power of class A large signal amplifier in terms
of V-*, V*i* I*u" and I6n. t8]
(b) What is meant by crossover distortion in class B amplifier? Explain how it is
overcome in class AB operation. t8l
OR
Q.5 (a) Explain complimentary and quasi complimentary symmetry push pul1 power
amplifier with the help of circuit diagrams. l8l
(b) A class B push - pull amplifier is supplied with v65 = 50v. The signal swings
the collector voltage down to Vnin = 5V. The total dissipation in both transistors
is 40W. Find the total power conversion efficiency. t8l

l4E412o) Page 4 of4 [1ss6ol