## Saturday, October 6, 2012

### EC2305 TRANSMISSION LINES AND WAVEGUIDES NOVEMBER/DECEMBER 2010 ANNA UNIVERSITY QUESTION PAPER

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010
Fifth Semester
Electronics and Communication Engineering
EC 2305 — TRANSMISSION LINES AND WAVEGUIDES
(Regulation 2008)
Time : Three hours Maximum : 100 Marks
PART A — (10 × 2 = 20 Marks)

1. A constant-K T-section high pass filter has a cutoff frequency of 10 KHz. The design impedance is 600 ohms. Determine the value of L.
2. What are the advantages of m-derived filters?
3. Define delay distortion.
4. Write the expressions for the phase constant and velocity of propagation for telephone cable.
5. A lossless line has a characteristic impedance of 400 ohms. Determine the standing wave ratio if the receiving end impedance is 800 +j 0.0 ohms. 6. Write the expressions for the input impedance of open and short circuited dissipationless line.
7. Define the cutoff frequency for the guided waves.
8. For a frequency of 6 GHz and plane separation of 3 cm, find the group and phase velocities for the dominant mode.
9. Calculate the cutoff wavelength for the TM11 mode in a standard rectangular waveguide if a = 4.5 cm.
10. Give the applications of cavity resonators.

PART B — (5 × 16 = 80 Marks)

11. (a) (i) Design a m-derived T-section low pass filter having a cutoff frequency (fc) of 5000 Hz and a design impedance of 600 ohms. The frequency of infinite attenuation is 1.25 fc. (8)
(ii) Draw and explain the operation of crystal filters. (8)
Or
(b) (i) Design a constant-K T-section bandpass filter with cutoff frequencies of 1 KHz and 4 KHz. The design impedance is 600 ohms. (8)
(ii) Draw a constant-K T-section band elimination filter and explain the operation with necessary design equations. (8)
12. (a) (i) A transmission line has the following per unit length parameters : L = 0.1Î¼ H, R =5 ohms, C = 300 pF and G = 0.01 mho. Calculate the propagation constant and characteristic impedance at 500 MHz. (8)
(ii) Derive the conditions required for a distortionless line. (8)
Or
(b) (i) The characteristic impedance of a uniform transmission line is 2309.6 ohms at a frequency of 800 MHz. At this frequency, the propagation constant is 0.054(0.0366 + j 0.99). Determine Rand L. (6)
(ii) Explain the reflection on lines not terminated in characteristic impedance with phasor diagrams. Define reflection coefficient and reflection loss. (10)
13. (a) (i) Draw and explain the operation of quarter wave line. (8) (ii) It is required to match a 200 ohms load to a 300 ohms transmission line to reduce the SWR along the line to 1. What must be the characteristic impedance of the quarter wave transformer used for this purpose if it is directly connected to the load? (4)
(iii) What are the drawbacks of single stub matching and open circuited stubs? (4)
Or
(b) (i) Draw and explain the principle of double stub matching. (8)
(ii) A UHF lossless transmission line working at 1 GHz is connected to an unmatched line producing a voltage reflection coefficient of 0.5(0.866 + j 0.5). Calculate the length and position of the stub to
match the line. (8)
14. (a) (i) Explain the transmission of TE waves between parallel perfectly conducting planes with necessary expressions and diagrams for the field components. (12)
(ii) A TEM wave at 1 MHz propagates in the region between conducting planes which is filled with dielectric material of r Î¼ = 1 and r Îµ = 2. Find the phase constant and characteristic wave impedance. (4)
Or
(b) (i) Explain the reasons for the attenuation of TE and TM waves between parallel planes with necessary expressions and diagrams. (10)
(ii) Write a brief note on the manner of wave travel and their velocities between parallel planes. (6)
15. (a) (i) Discuss the propagation of TM waves in a rectangular waveguide with relevant expressions and diagrams for the field components. (10)
(ii) A rectangular waveguide measuring a = 4.5 cm and b = 3 cm internally has a 9 GHz signal propagated in it. Calculate the guide wavelength, phase and group velocities and characteristic impedance for the dominant mode. (6)
Or
(b) Explain the propagation of electromagnetic waves in a cylindrical waveguide with suitable expressions.(16)
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### LINEAR INTEGRATED CIRCUITS MAY/JUNE 2012 QUESTION PAPER

B.E/B.Tech. DEGREE EXAMINATION, MAY/JUNE 2012.
Fourth Semester .
Electronics and Communication Engineering
LINEAR INTEGRATED CIRCUITS
(Common to PTEC 2254 Linear Integrated Circuits for B.E.(Part -Time) - ThirdSemester ECE - Regulation 2009)
(Regulation 2008)
Subject Code : EC 2254/l47404/EC 44/10144 EC 405/EC 1254/080290022
Subject Name : LINEAR INTEGRATED CIRCUITS
Time : Three hours                                                                          Maximum: 100 marks
PART A—(lOx2= 2Omarks)
1. What are the two requirements to be met for a good current source?
2. List the various methods of realizing high input resistance in a differential amplifier.
3. Why active guard drive is necessary for an instrumentation amplifier?
4. What is comparator?
5. What are the advantages of variable transconductance technique?
6. VCO is also called as V-f converter. Why?
7. Define settling time of D/A converter.
8. What is the main drawback of dual slope ABC?
9. What are the limitations of three terminal regulator? .
10. What is a switched capacitor filter?
PART B — (5 x 16 = 80 marks)
11. (a) (i) With neat circuit diagrams, explain the operation of
(1) voltage reference circuit using temperature compensation
(2) voltage reference circuit using avalanche diode reference.                (12)
(ii) The current mirror shown below, is to provide a 1 mA current with Vcc = 10V.Assume ÃŸ 125 and VBE = 0.7V.
(1) Determine the value of R1
(2) Also, for a collector current of 10 micro amperes, find the value of R1.             (4)
Or
(b) (i) List and explain the non-ideal DC characteristics of an operational amplifier. (8)
(ii) Explain the AC characteristics of an operational amplifier.
12. (a) (i) Sketch the basic circuit using op-amp to perform the mathematical operation of differentiation and explain. What are the limitations of an ordinary OP-AMP differentiator? Draw and explain the circuit of
a practical differentiators that will eliminate these limitations. (8)
(ii) Draw and explain the circuit of a voltage to current converter if the load is
(1) Floating
(2) Grounded.
Or
(b) (i) Explain the working of OP-AMP based Schmitt trigger circuit. (8)
(ii) Design an OP-AMP based second order active low pass filter with cut offfrequency 2 kHz. (8)
13. (a) (i) List and define the various performance parameters of a Multiplier IC. (6)
(ii) How the multiplier is used as voltage divider? (5)
(iii) How the multiplier is used as frequency doubler? (5)
Or
(b) Explain, with neat block diagrams, how PLL is used as
(i) AM Detector . (5)
(ii) FM Detector . (5)
(iii) Frequency Synthesizer. (6)
14. (a) (i) Explain the following types of electronic switches used in D/A converter, with suitable diagrams:
(1) Totem pole MOSFET switch (4)
(2) CMOS inverter as a switch. . (4)
(ii) Explain the working of R-2R ladder DAC, by taking example of a 3-bit DAC circuit. Sketch the corresponding equivalent circuits and hence obtain the equation for output. (8)
Or
(b) (i) With neat circuit diagram and wave form of output, explain the working of Dual slope A/D converter. (10)
(ii) Give a table of comparison of Flash, Dual-slope and Successive approximation ADCs, in terms of parameters like speed, accuracy, resolution, input-hold-time. (6)
15. (a) Sketch the functional block diagram of the following and explain their working principle:
(i) IC 555 Timer. (8)
(ii) General purpose voltage regulator IC 723. (8)
Or
(b) (i) With neat diagram, explain the working principle of isolation amplifier. (8)
(ii) With neat diagram, explain the principle of operation of optocouplers. (8)

### ANNA UNIVERSITY FIRST SEMESTER JANUARY 2013 TIMETABLE | 1ST SEMESTER TIMETABLE FOR 2012 BATCH |ANNA UNIVERSITY

19/01/2013 - MA2111 Mathematics I
21/01/2013 - PH2111 Engineering Physics I
23/01/2013 - CY2111 Engineering Chemistry I
28/01/2013 - GE2112 Fundamentals of Computing and Programming
29/01/2013 - HS2111 Technical English I

31/01/2013 - GE2111 Engineering Graphics **
31/01/2013 - GE2111 Engineering Graphics **

Note:

** Examination for the subject  GE2111 Engineering Graphics is scheduled on 31/01/2013 (Forenoon & Afternoon). The session for the subject for various branches will be announced by the respective colleges. Tamil medium students will take the Examination in the Forenoon session only.

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### Anna University, Chennai 2008,2009 &2012 Batches, erstwhile Anna University of Technology, Chennai 2010 Batch and all erstwhile Anna University of Technologies-2011 Batch-(R2008)

Anna University Nov/Dec 2012 Applicable For

Chennai 2008,2009 , 2012 Batches

erstwhile Anna University of Technology, Chennai 2010 Batch and
all erstwhile Anna University of Technologies-2011 Batch-(R2008)