Cusat Ec 4th Sem Question Paper

BTS(C) — IV— 10 — 015 — D

B. Tech Degree IV Semester Examination, April 2010EC/EE 405 ANALOG COMMUNICATION

(2006 Scheme)Time : 3 Hours Maximum Marks : 100

PART A(Answer ALL questions)

(8 x 5 = 40)

I. a. A SmHz RF carrier is modulated with a 3KHz audio tone. The maximum peak to peakvoltage is 20V and minimum peak to peak voltage is 10V fmd

Modulation indexSide band frequencies

(iii) Carrier power

Define the terms (i) Vestigial side band modulation (ii) High level slow level modulation.Explain the following terms (i) Pre-emphasis (ii) De-emphasis.Draw the block schematic of FM receiver.Compare AM and FM.Explain traffic load and grade of service in Telephone system.Write short notes on DTMF dialing.

h. Define sensitivity and selectivity associated with communication receiver.

PART B(4 x 15%0)

II. Derive from fundamentals, the power derived in an amplitude modulated signals, (10)

Explain the SSB method of modulation. (5)OR

III. Explain Double-tuned super heterodyne receiver. (12)

Explain the principle of operation of envelope detector. (3)

IV. Draw and explain the complete block diagram of Armstrong Frequency modulationsystem. (10)Compare narrow Bend FM and wide band FM. (5)

ORV. Explain FM stereo receiver. (10)

Explain the working of balanced slope detectors. (5)

VI. Discuss the types, causes and effects of various terms of noise in communicationsystem. (12)What is the importance of AGC circuit in receiver? (3)

ORVII. a. Write short notes on

Capture effectImage frequency and its rejectionCarrier thresholdingDouble spotting (12)

b. What is none temperature? (3)

VIII. Explain different types of signaling. (9)Briefly explain the operation of cross bar type telephone exchanges. (6)

ORIX. Explain different types of tones used in automatic telephony.

Write short note on(9)

Traffic variationIn channel signalling. (6)

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BTS (C) —IV — 10 — 013 — E

B. Tech Degree IV Semester Examination, April 2010EC/EI 403 ELECTRONIC CIRCUITS II

(2006 Scheme)

Time: 3 Hours Maximum Marks: 100PART — A

(Answer ALL questions)(8 x 5 = 40)

I. (a)

(0

11. (a)

(b)

III. (a)

(b)

What are the conditions to obtain sustained oscillation from an oscillator?Briefly explain the major advantages of negative feed back.Illustrate how the dead band in the class B power amplifier transfer characteristicresults in cross over distortion. Also derive the efficiency of the class B power amplifier.Determine the second harmonic distortion in power amplifiers.Differentiate between synchronous tuning and stagger tuning.What do you mean by unilateralisation of transistors? What are its advantages?What are the four differential amplifier configurations? Which one is not commonlyused and why?What is a level translator circuit? Why it is used with the cascaded differential amplifiers?

PART — B

With diagrams, explain why an amplifier with unbypassed emitter is a currentseries feedback. Also derive the input impedance and output impedance.With neat diagram explain the collpits oscillator.

ORExplain the working of a weinbridge oscillator. When is the bridge is balanced?Why it is called a lead-lag network.Show that the series voltage negative feedback increases the input impedance ofan amplifier by a factor of (1+A/3).

(4 x 15 = 60)

(8)(7)

(10)

(5)

IV. (a) For a given power amplifier the output current varies as follows.

I„,,„, = 2.5A, 1„„„ =1.8A with I.p =2A and RL = 852. Find

Second Harmonic DistortionPower delivered by the fundamental component of output current to the load

(iii) Total power delivered to the load. (8)(b) Explain the transformer coupled class AB power amplifier with neat diagram. (7)

ORV. (a) What is power amplifier? In what respect does it differ from a voltage amplifier. (10)

(b) What is class D power amplifier? Explain. (5)

Which are the broadbanding techniques? Explain with neat diagrams. (15)OR

(a) What is cascode amplifier? Explain with neat diagram. What are its advantages? (8)(b) Draw the circuit of a double tuned amplifier. Explain the circuit operation and

plot the frequency response curve. What are its advantages? (7)

VIII. (a) What are the ideal characteristics of an op-amp? (3)Briefly explain the following terms:(i) CMRR (ii) SVRR (iii) Slew rate (6)What do you mean by virtual ground? How it differ from actual ground? (3)

(d) Briefly explain the internal block schematic of a typical op-amp. (3)OR

Draw the circuit of a dual input balanced output differential amplifier. Find outthe emitter current and collector emitter voltage. Also show that it amplifies thedifference between the two input signals and voltage gain is independent of emitterresistance. (15)

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BTS(C) — IV — 10 — 016 — A

B. Tech Degree IV Semester Examination, April 2010

EB/EC/EUEE 406 INDUSTRIAL AND POWER ELECTRONICS(2006 Scheme)

Time : 3 Hours Maximum Marks : 100

PART- A(Answer ALL questions )

(8 x 5 = 40)

Explain the structure and characteristics of a power MOSFET.Briefly explain the different methods of burning on of an SCR.Draw and explain the circuit of a single phase full wave rectifier with a resistive load.Describe briefly any one scheme used for controlling the speed of a separately excited dcmotor.Explain the working of single phase parallel inverter.Explain the working of Jones Chopper.Explain the working of on-line and off-line UPS with the help of block diagrams.Explain how thyrister is protected against over voltage and over current.

PART- B

(4 x 15 = 60)

(a) Draw and explain the V-I characteristics of an SCR.(b) Explain construction and working of a TRIAC.

OR(a) Explain the problems associated with the series and parallel operation of SCRs.(b) Draw and explain an RC trigger circuit for an SCR.

Derive an expressions for the average output voltage of a single phase full wavefully controlled bridge converter, supplying RL load.

ORDraw the circuit of a 3d full wave rectifier with R load and explain its working withsuitable wave forms.

Explain the various commutation schemes for SCR.OR

Describe any one scheme for controlling the speed of a 3 phase induction motor.

With circuit diagram, explain the operation of a battery charging scheme.OR

Explain the principle of induction heating. What are its applications?

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BTS(C) — IV— 10 —012 — L

B. Tech Degree IV Semester Examination, April 2010CS/EB/EC/EI 402 MICROPROCESSORS

(2006 Scheme)

Time: 3 Hours Maximum Marks: 100

PART A(Answer ALL questions)

(8 x 5 -= 40)

I. a. Write a short note on usage of temporary registers in 8085.Write the usages of 8085 pins (i) READY (ii) ALEDifferentiate between the op-codes LHLD and LDAX.Write a short note on various rotate instructions and their functionalities in 8085.Write a short note on (i) T State (ii) Machine cycleDraw an Instruction Fetch Timing Diagram of 8085.Write a short note on various ports available in 8255.

h. Write a note on Transmitter section of 8251 peripheral device.

II.

PART B(4 x 15

Differentiate between I/O Mapped I/O and Memory mapped I/O mapping techniques.

= 60)

(8)

Describe the Register organization of 8085 in detail. (7)OR

III. Write the functions of following group of pins in 8085.(i) SO, SI (ii) HOLD, HLDA (iii) SID, SOD (15)

IV. Explain various addressing modes available in 8085 with the help of examples.Design and write a Delay routine for 1 second delay. Assume the clock speed of

(8)

microprocessor is 3 MHz. (7)

OR

V. Write an assembly Language program in 8085 to range a set of numbers stored frommemory address 3001 onwards in ascending order and number of elements in the setis available in location address 3000.Write a short note on stack based op-codes and how will it modify the contents of

(10)

register SP. (5)

Draw and explain the timing diagram for the instruction LDA 3000. (15)

ORDescribe various types of interrupts and their organization in 8085. (15)

VIII. a. Write the concept of memory interfacing with the help of an example. (8)

b. Draw the architecture and register organization of peripheral chip 8251. (7)OR

IX. Describe various operating modes and control words of peripheral chip 8255.Design an interface circuit to accept 8 bits of data from a ADC and produce variouscontrol signals according to

(5)

the data read is less than 128The data read is equal to 128

(iii) The data read is greater than 128

Also write the program for implementing the interfacing circuit.

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BTS (C) — IV — 10 — 014 — G

B. Tech Degree IV Semester Examination, April 2010EC/EI 404 SIGNALS AND SYSTEMS

(2006 Scheme)

Time : 3 Hours Maximum Marks : 100

PART - A(Answer ALL questions)

(8 x 5 = 40)

I. (a) Compare energy and power signals.

(b) Explain the linearity property of a system and test whether the following signalsare linear or not :

dy I dt +3t y(t)= t2x(t)

y(t) =ex(t)

(c) Test whether the following systems are time — invariant or not

y(n)= x(n)+nx(n -1)

y(n)=x(2n)

Find the 4 — point DFT of x (n). {1,-2, 3, 41

Explain autocorrelation and variance.List the properties of power spectral density.Write brief notes on white noise.Write short notes on matched filters.

PART — B(4 x 15 = 60)

II. Check whether the following systems are (a) causal or non-causal (b) staticor dynamic

(i) y( t)cPy(t)1 dt +3t dy(01 dt+ y(t)= x(t)n+1

Y(n) = x(k)K=-0c,

(iii) y(n)= cos[x(n)] (3 x 5 = 15)

ORiii. n List and prove the pig:elides of convolution. (10)

(o) Chck whether the following system with impulse response h (t) is stable

or not. (i) h(t).: 4e-2111. (5)

(Turn Over)

2

(a) Determine the output response y (n) if x (n) = {1,2,3,2} & h (n) = 11,2, 21. (10)

(b) Find the inverse fourier transform of

X (eft' ). 1 ; 4 <= i wi <=. 3n/ 4

and 0 ; 3r1/ 4 <=lwl<= n,0 <= <= n/ 4 (5)

OR

Find the z transform of the signal x = [sin wo n] u (n) and hence find ROC. (15)

VI. Write short notes on :Random processStationary and non — stationary random processErgodic process. (3 x 5 = 15)

ORVII. (a) Explain the probability density function. (10)

(b) A random variable has a probability distribution function given by

F(x)=0 ; -co < x SO

=1 - C2x ; 0<x<co

Find (i) the probability that x > 0.6the probability that x 5 0.25the probability that 0.4 < x 5 0.8 (5)

VIII. Explain (i) Narrow band noiseEffective noise temperaturePre-emphasis and De-emphasis filtering.

ORDerive an expression for noise figure in a communication system.

(3 x 5 = 15)

(15)

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