EC 2205 Electronics Circuits 1 (EC1) - III Semester - IMPORTANT QUESTIONS FOR NOV/DEC 2013

Unit 1 : MIDBAND ANALYSIS OF SMALL SIGNAL AMPLIFIERS

PART –A
1. What do you understand by Operating point? (2)
2. Why do we choose the Q point at the center of the load line? (2)
3. Name the two techniques used in the stability of the q point .explain.? (2)
4. Define stability factor &Give the expression for stability factor? (2)
5. List out the different types of biasing. (2)
6. What do you meant by thermal runway? (2)
7. Why transistor is called as a current controlled device? (2)
8. Define current amplification factor? (2)
9. What are the requirements for biasing circuits? (2)
10. When does a transistor act as a switch? (2)
11. What is biasing? (2)
12. What is an operating point? (2)
13. What is d.c load line? (2)
14. Explain about the various regions in a transistor? (2)
15. Explain about the characteristics of a transistor? (2)
16. Why the operating point is selected at the Centre of the active region? (2)
17. What is an amplifier? (2)
18. What is small signal amplifier? (2)
19. What is aDarlingtonpair? (2)
20. Define Common Mode Rejection Ratio. (2)
21. What is meant by Differential Amplifier? (2)
22. What do you mean by balanced and unbalanced output? (2)
23. What are the methods of improving CMRR? (2)
24. Give few applications of differential amplifier (2)
25. What are the advantages of double tuned over single tuned? (2)
26. List the four differential amplifier configurations (2)


PART –B
1. Draw the circuit of a common source FET amplifier & explain its operation? (16)
2. Briefly explain the operation of aDarlingtonemitter follower and also derive an
expression for its performance measures? (16)
3. What is a differential amplifier? Explain its working in common mode operation.
Obtain its AC equivalent circuit & drive the expression for voltage gain? (16)
4. Draw the circuit diagram of a differential amplifier. Explain the operation in difference
mode and common mode? (16)
5. What are the methods to improve the CMRR of differential amplifier? Detail any two
of them. (16)
6. i) What is meant by bias stability? What factors affect BJT biasing? (8)
ii)With the help of neat diagram explain the voltage divider biasing method for JFET
(8)
7. i) Explain with circuit diagram the boot strappedDarlingtonemitter follower. (8)
ii) Draw the circuit diagram of self-bias circuit using CE configuration and explain
how it stabilizes operating point. (8)
8. Draw the small signal hybrid model of CE amplifier and derive the expression for its
AI.AV,RI and RO. (16)


UNIT II
FREQUENCY RESPONSE OF AMPLIFIERS
PART –A
1. Draw a hybrid-π model for a BJT. (2)
2. What is the relationship between bandwidth and rise time? (2)
3. What are the high frequency effects? (2)
4. If the rise time of a BJT is 35 nano seconds, what is the bandwidth that can be
obtained using this BJT? (2)
5. Explain the usefulness of the decibel unit. (2)
6. Define the term bandwidth of an amplifier? (2)
7. State various capacitances in the hybrid model? (2)
8. Define the term bandwidth of an amplifier? (2)
9. Why it is not possible to use the h- parameters at high frequencies? (2)
10. What do you mean by the half power or 3 db frequencies? (2)
PART –B
1. Derive the expression for the CE short circuit current gain of transistor at high
frequency (16)
2. i)What is the effect of Cb’e on the input circuit of a BJT amplifier at High
frequencies? (8)
ii)Derive the equation for gm which gives the relation between gm, Ic and
temperature. (8)
3. i) Draw the high frequency hybrid –π model for a transistor in the CE
configuration and explain the significance of each component. (12)
ii) Define alpha cut off frequency. (4)
4. i) Define fα,fβ and fT and state the relation between fβ and fT (8)
ii) Explain the significance of octaves and decades. (8)
5. Define unity gain frequency. Obtain the necessary relation using transistor
frequency response. (16)
6. Using hybrid π model for CE amplifier. Derive an expression for its short circuit
current gain. (16)
7. Explain the operation of low frequency response CE amplifier. (16)


UNIT III


UNTUNED AMPLIFIERS
PART A
1. What is an effect of cascading? (2)
2. What are all the factors affecting the bandwidth of the RC
Coupled amplifier? (2)
3. Explain bypass capacitor? (2)
4. What is meant by coupling capacitor? (2)
5. Why does amplifier gain reduce? (2)
6. Explain the different regions in frequency response? (2)
7. State the types of distortions in amplifier? (2)
8. What is cross over distortion? How it can be eliminated? (2)
9. Define noise? (2)
10. Define step response? (2)
PART –B
1. Describe in detail about the different types of distortions occur in amplifier?(16)
2. i) Explain the concept of frequency response of an amplifier? (8)
ii) Classify the amplifiers? (8)
3. With the neat sketch describe the principle of operation of RC coupled amplifier?
(16)
4. Explain the operation of low frequency response CE amplifier and also discuss
the effect of bypass capacitor? (16)
5. Draw the equivalent circuit of cascaded CE stage and also derive an expression
for its performance measures? (16)


UNIT IV
FEEDBACK AMPLIFIER AND OSCILLATORS
PART –A
1. What is feed back and what are feed back amplifiers? (2)
2. What is meant by positive and negative feedback? (2)
3. What are the advantages and disadvantages of negative feed back? (2)
4. Differentiate between voltage and current feedback in amplifiers? (2)
5. Define sensitivity? (2)
6. Define De-sensitivity? (2)
7. What is the type of feedback used in an op- amp Schmitt trigger? (2)
8. Give the expression for the frequency of oscillations in an op-amp sine wave
oscillator? (2)
9. What are the conditions for sustained oscillator or what is Backhouse criterion?(2)
10. What is Oscillator circuit? (2)
11. What are the classifications of Oscillators? (2)
12. What are the types of feedback oscillators? (2)
13. Define Piezo-electric effect? (2)
14. Draw the equivalent circuit of crystal oscillator? (2)
15. What is Miller crystal oscillator? Explain its operation? (2)
16. State the frequency for RC phase shift oscillator? (2)
17. Give the topology of current amplifier with current shunt feedback? (2)
18. What are gain margin and phase margin? (2)
19. What is the minimum value of hfe for the oscillations in transistorized RC
Phase shift oscillator? (2)
20. What is LC oscillator? (2)
21. Draw the circuit of clapp oscillator? (2)
22. How does an oscillator differ from an amplifier? (2)
23. Name two low frequency oscillators? (2)
24. Calculate the frequency of oscillation for the clapp oscillator with c1=0.1μf,
c2=1μf, c3=100pF and L=470μH (2)
PART –B
1. Discuss the differential voltage/current—series/shunt feedback connections with
expression for gain, input resistance and output resistance. (16)
2. Draw and explain various feedback amplifier topologies? (16)
3. i) explain the operation of Hartley oscillator. (10)
ii) Find the value of inductor in the Colpitts oscillator if c1=0.2μf, c2=0.02μf
And the frequency of the oscillator is 10 kHz. .Find the required gain for
Oscillator? (6)
4. Discuss in detail the characteristics of negative feedback amplifier? (16)
5. i) Give a short note on crystal oscillator? (8)
ii) Determine the voltage gain, input and output amplifier with feedback for
Voltage series feedback having A =-100, Ri=10kΩ, Ro=20 kΩ and β= -0.1 (8)
6. With a neat circuit diagram explain the working of RC phase shift oscillator.
Derive the expression for its frequency of oscillator? (16)
7. With a neat circuit diagram explain the working of Wien bridge phase shift
oscillator. Derive the expression for its frequency of oscillator? (16)
8. With the topologies compare the four types of negative feedback amplifier?(16)
9. Draw and explain the Colpitts oscillator circuit and determine the frequency of
oscillator? (16)



UNIT V
LARGE SIGNAL AMPLIFIERS
PART –A
1. What is class AB operation? (2)
2. Define conversion efficiency of a power amplifier. What is its value for class C
power amplifier? (2)
3. What is crossover distortion? How it can be eliminated? (2)
4. What is meant by Harmonic distortion? (2)
5. What is the drawback of class B amplifier? How is this minimized? (2)
6. Define thermal resistance in the context of power amplifier. (2)
7. What are the types of class B amplifier? (2)
8. Draw a quasi complimentary symmetry power amplifier? (2)
9. What is the advantage of using the output transformer for a class A amplifier? (2)
10. What is the disadvantage of transformer coupled class A amplifier? (2)
PART –B
1. i)Draw a neat circuit diagram of push-pull class-B amplifier. Explain its working.(8)
ii) For the transformer – coupled class A power amplifier circuit derive the expression
for its efficiency. (8)
2. Prove that the maximum efficiency of class B amplifier is 78.5%. and that of Class A
type is 50%. (16)
3. Draw the circuit of push pull class B power amplifier coupled using transformers and
explain the operation. Prove that all the even harmonics get eliminated. What is the
assumption made for this? (16)
4. i) Compare class A, class B and class C power amplifier in their performance and
efficiency. (10)
ii) Give the design procedure for heat sinks. (6)
]
5. What is the difference between a voltage amplifier and a power amplifier? (16)
6. Discuss the advantage and disadvantage of a complementary symmetry class b
amplifier? (16)
7. With the help of neat diagram. Explain the characteristics of class A amplifier and
also derive an expression for its efficiency and figure of merit. (16)

EC2402 Optical Communication And Networking Important Question For Nov/Dec 2012 Anna University Examinations

Anna University, Chennai Nov/Dec -Important Questions

Optical Communication And Networking EC2402

VII Sem ECE

Unit I-V

 

1.     Discuss the mode theory of circular waveguide

2.     Discuss the propagation modes in single -mode fiber

3.     What are the fiber modes? Explain mode theory for optical fibers in detail

4.     Compare Single mode fibers and Graded index fibers. Explain the requirements for fiber materials

5.     Explain various types of fiber splicing techniques and fiber connectors

6.     Discuss various kinds of losses that an optical signal might suffer while propagating through fiber, Which is most important one? What is the effect of these losses on light power and pulse shape

7.      Derive an expression for material dispersion

8.     Discuss the signal distortion in single mode fibers

9.     Discuss the LASER diode principle , modes and threshold conditions

10.Derive the internal quantum efficiency of an LED.

11. Describe the characteristic of responsivity against wavelength for an ideal silicon photodiode with the help of its expression

12.Derive the internal quantum efficiency and shows the variation in threshold current with temperature for ILD

13. Draw and explain the operation of high impedance FET and BJT preamplifiers

14.Explain the error sources of fundamental receiver operations. Discuss the performance of digital receiver by defining the probability of error

15. Explain the following i) Fiber attenuation measurements, ii) Fiber cutoff wavelength measurements

16.Explain fiber diameter and numerical aperture measurements

17. Explain the basic frame structure and network architecture of SONET

18.Explain the salient feature of solitions using relevant expressions and diagrams

19.Explain the Ultra high capacity WDM systems and discuss the system performance of WDM and EDFA

EC2312 COMMUNICATION ENGINEERING IMPORTANT QUESTIONS FOR NOV/DEC 2012 EXAMS

Anna University, Chennai Nov/Dec 2012 - Important Questions

EC2312 - COMMUNICATION ENGINEERING

V Sem EEE

Unit I-V

1.     Draw the block diagram of low level AM transmitter and explain

2.     Derive an expression for amplitude modulated wave and its power relations. Also give time and frequency domain representation

3.     Explain super heterodyne receiver with suitable block diagram

4.     Describe the operation of frequency division multiplexing

5.     Explain the principle of indirect method of frequency modulation With neat sketch

6.     Describe pulse code modulation scheme and draw the wave forms

7.      Explain the working of QAM modulator and detector with the signal constellation diagram

8.     Draw the block diagram of BPSK transmitter and receiver. Explain the same digital modulation scheme with appropriate constellation diagram

9.     Draw the block diagram of a TDM system and explain where TDM is applied

10.Explain delta modulation with suitable wave forms and list its advantages and disadvantages

11. How do you generate PPM from PDM?         

12. Explain the working of FSK modulator and detector with the signal constellation diagram

13. Explain the generation and demodulation of PWM wave.

14.Five source messages are probable to appear as m1=0.4, m2=0.15, m3=0.15, m4=0.15, m5=0.15 . Find the coding efficiency for 1. Shannon Fano coding, 2. Huffmann Coding

15. Explain Frequency Hop Spread spectrum and the two types in detail

16.Draw the block diagram of a TDM system and explain where is TDM applied

17. Explain CDMA. Compare FDMA, TDMA and CDMA 

18 What are the essential components required for establishing an optical link.What are the various losses associated with it?

19 What are the benefits of satellite communication? How is the position of satellite tracked from the earth station? Derive the satellite link equations and comment on it

20 Explain the principle of operation of light sources and detectors.

EC2304/Microprocessors & Microcontrollers Anna Univ,Chennai Nov/Dec 2012 Important Questions

Anna University, Chennai Nov/Dec 2012 -Important Questions

EC2304/Microprocessors & Microcontrollers

V Sem ECE

Unit I-V

 

1.     Explain the 8085 the generation of dedicated address and data bus signals from multiplexed address/data bus

2.     Explain the  8086  interrupt types in detail

3.     Explain the internal hardware architecture of 8086 microprocessor with neat diagram

4.     Briefly  explain the concept  of DMA

5.     Explain the relative addressing  mode and  string addressing  mode  with its syntax in 8086

6.     Explain the data transfer group  and logical group of 8086 instructions

7.      Explain  the  few  assembler  directives  with  suitable examples

8.     What are the instruction set of 8086 ? Explain each briefly

9.     Write neat block diagram explain the 8279 keyboard display  controller and  its software   commands

10.Explain the interfacing of any 8 bit A/D converter with a 8086 microprocessor. Also write a necessary assembly language program for conversion

11. Write neat block diagram explain the 8255 Programmable peripheral  interface and its operating modes

12.Explain the memory  organization of 8051 microcontroller 

13. Explain the program control transfer  instructions in 8051

14.Explain the  serial port operation  of 8051 microcontroller

15. Explain the timer  operation of  8051

16.Draw and explain the  washing machine control with  8051 microcontroller. And also write   an  ALP  for  control

17. Draw  and explain the block diagram of traffic light control system with program

18.Draw and explain the diagram to interface a stepper motor with a 8051 microcontroller. Also  write  an  ALP to run the stepper motor in both forward and reverse direction with delay

19.Draw and explain the  washing machine control with  8051 microcontroller. And also write   an  ALP  for  control

DIGITAL CONTROL SYSTEM Anna University Important Questions Nov/Dec Exams 2012

Anna University Important Questions

Anna University Important Questions for Digital Control System ,

1.	Distinguish between analog and discrete signalsAnalog signals are continuously vary with time, frequency and space but discrete signals do not have continuous signal. It produces output only at different instants.
2.	What are the advantages of digital control over conventional control?Flexibility, Wide selection of control algorithm, integrated control of industrial systems, Future generation control system.
3.	What is sampling? How it is achieved?Sampling is a process of converting continuous signal into discrete signal with proper selection of sampling period / frequency. Sampling is achieved by sample and hold device.
4.	How information loss happens due to sampling.In practice, signals in control system include low frequency components carrying useful information, as well as frequency noise components. The high frequency components appear as low frequency signals due the aliasing effect, causing a loss of information.
5.	Obtain the Z transform of e-atsinωtZ { e-at x(t) } = X ( z e-at) Z { sinωt } =  Z { e-atsinωt } =
6.	What is the use of modified Z transform?The Z transform method determine the transient responses of sampled –data control systems only at the sampling instant. To obtain the values of the response between sampling instants, modified Z transforms are useful. They are also helpful in analyzing sampled data control systems containing transportation lag.
7.	Obtain the closed form solution of state difference equationThe state equation is The solution for this equation in closed form is
8.	When the losses occur in controllability and Observability?Losses of controllability and Observability due to sampling may occur only when the continuous time system has oscillary modes and the sampling interval is half the period of oscillation of an oscillatory mode or an integer multiple of that period.
9.	Distinguish between velocity form and position form of Digital PID algorithm. Position form Velocity form it requires initialization of controller output it does not need initialization of controller output it does not protect against integral windup as sum or error sequences are not computed it is protected against integral windup as sum or error sequences are not computed. it does not protect the process against computer failure it protects the process against computer failure it produces bump transfer it produces bumpless transfer
10.	What is pole placement?Finding the elements of control gain matrix K so that the roots of the characteristic equation ( i.e., the poles of the closed loop system ) are in the desired location is called pole placement. The parameters are iterated in the compensators to find acceptable closed loop root locations with full state feedback.