EC202- ELECTRONIC CIRCUITS II Unit- I -FEEEDBACK AMPLIFIER 1. What is feedback? What are the types of feedback? 2. Define positive feedback. What are its merits and demerits? 3. Define negative feedback. What are it merits and demerits? 4. What is the effect of negative feedback amplifier. State the function of each block. 5. Derive the relationship between the transfer gain with feedback Af and that without feedback A. 6. What is loop gain? 7. What is sensitivity? 8. What is desensitivity? 9. What is the effect of input resistance of the amplifier with series feedback connection and shunt feedback connection? 10. What is the effect of output resistance of the amplifier with series feedback connection and shunt feedback connection? 11. Sketch the circuit of single stage CE Amplifier that uses Volt sampling and shunt mixing. 12. Determine the voltage gain, input gain and out impedance with feedback for voltage- Series feedback 13. Determine the voltage gain, input gain and out impedance with feedback for Voltage-shuntfeedback 14. Determine the voltage gain, input gain and out impedance with feedback for Current - Series feedback 15. Determine the voltage gain, input gain and out impedance with feedback for Current - Shunteedback Part B 1. Give the block diagram of a general feedback amplifier. State the function of each block 2. Using illustrations, explain the effects of negative feedback on the amplifier performance 3. (a) Identify the four possible topologies of a feedback network. (b) Identify the o/p signal & f/b signal for each topology (Whether current or voltage) (c) Identifiy the transfer gain & feedback factor for each topology. 4. Draw the block diagram of current sampling Series Mixing feedback configuration and derive an 5. Draw the block diagram of current sampling Shunt Mixing feedback configuration and derive an 6. Draw the block diagram of Voltage sampling Series Mixing feedback configuration and derive an 7. Draw the block diagram of Voltage sampling Shunt Mixing feedback configuration and derive an 8. Sketch the circuit of a single stage CC Amplifier that uses voltage sampling Series Mixing. Explain the
operation of circuit. Derive expression for Af, Rif, Rof 9. Sketch the circuit of a single stage CA Amplifier that uses voltage sampling Shunt Mixing. Explain the operation of circuit. Derive expression for Af, Rif, Rof 10. For given amplifier with CE configuration, determine i) the types of negative feedback ii) draw the equivalent circuit. iii)?. A, Af, Avf, Rif & Rot. Assume hre = hoe = 0 11. For given amplifier, determine i) the types of negative feedback ii) draw the equivalent circuit. iii)?. A, Af, Avf, Rif & Rot. Assume hre = hoe = 0 12. For given amplifier, determine i) the types of negative feedback ii) draw the equivalent circuit. iii)?. A, Af, Avf, Rif & Rot. Assume hre = hoe = 0 UNIT II - OSCILLATORS Part A 1. Define an Oscillator. Give some examples 2. Distinguish between an amplifier and an oscillator. 3. How do you classify oscillator based on various aspects? 4. Define sinusoidal oscillator. Give examples. 5. Define non-sinusoidal oscillator. Give examples. 6. What are damped and undamped oscillations? Show waveforms. 7. What is a tank circuit or oscillatory? Explain its operation. 8. What are the factors responsible for damped oscillations in a LC tank circuit? 9. Explain the ways to overcome the losses in a tank circuit. 10. Explain the principle of operation of Transistor oscillator. 11. State Barkhausen criteria for sine wave oscillation and explain they must be fulfilled to sustain oscillations. 12. Draw the block diagram of a general feedback oscillator and explain how oscillations are produced. 13. Calculate the oscillator frequency for the Hartley oscillator for the following circuit values : LRFC = 0.5mH, L1 = 750µH, L2 = 750µH, M = 150µH and C = 150PF. 14. Calculate the oscillator frequency for the Colpitts oscillator for the following circuit values : LRFC = 0.5mH, L = 100µH, C1 = 150PF and C2 = 0.01µF. 15. What are the distinguishing features of Hartley and Colpitts oscillator? 16. What are the advantages of Clapp oscillator over Colpitts oscillator? 17. What are the disadvantages in LC oscillators? How is this overcome in RC oscillators? 18. What are the types of RC oscillators? 19. Explain the phase shift principle in Transistor RC Phase shift oscillator. 20. Sketch a diode amplitude stabilization circuit for a phase shift oscillator and explain its operation.
21. Calculate the operating frequency of a BJT Phase-Shift oscillator for R=6KO, C=1500PF, RC=18KO. 22. A 3 section RC Phase shift oscillator has R=10KO and C=0.01µF. (a) What is the frequency of oscillation? (b) If the oscillator is to be made variable, using the same values of R, what should be the tuning range of the capacitor to obtain a frequency range of 1KHz to 100KHz. 23. Sketch a diode amplitude stabilization circuit for a Wein-Bridge oscillator and explain its operation. 24. Calculate the operating frequency of a BJT Wein-Bridge oscillator for R=10KO and C=2400PF. 25. If the practical lower limit on C is 47PF in the Wein-Bridge oscillator, (a) What should be the fixed value of R to produce an upper frequency limit of 200KHz? (b) What should be the tuning range of C to provide a lower frequency limit of 20 Hz? 26. What are the factors that affect the frequency stability of oscillators? Explain. 27. What is piezoelectric effect? Draw the crystal equivalent circuit? 28. Why Quartz crystal is preferred over other crystal in crystal oscillators? 29. Brief about occurrence of series and parallel resonant condition in crystal oscillators Part B 1. Sketch the block schematic of a general LC oscillator and obtain an expression for sustained oscillations using Barkhausen criteria for sine wave oscillation. 2. Sketch the circuit diagram for a Hartley oscillator using a single-stage BJT amplifier. Explain the circuit construction and operation. Obtain expression for frequency of oscillation and condition for oscillation. 3. Sketch the circuit diagram for a Colpitts oscillator using a single-stage BJT amplifier. Explain the circuit construction and operation. Obtain expression for frequency of oscillation and condition for oscillation. 4. Sketch the circuit diagram for a Clapp oscillator using a single-stage BJT amplifier. Explain the circuit construction and operation. Obtain expression for frequency of oscillation and condition for oscillation. 5. Sketch the circuit diagram for a Tuned collector oscillator using a single-stage BJT amplifier. Explain the circuit construction and operation. Write expression for frequency of oscillation. 6. Sketch the circuit diagram for a Tuned Emitter oscillator using a single-stage BJT amplifier. Explain the circuit construction and operation. Write expression for frequency of oscillation. 7. Sketch the circuit diagram for a phase shift oscillator that uses a single stage BJT amplifier. Explain the circuit construction and operation. Obtain an expression for frequency of oscillation. 8. A phase shift oscillator is to use a feedback network consisting of 4 RC sections. Derive an approximate expression for the frequency of oscillation. 9. (a) What disadvantages does a phase shift oscillator have? (b) How is this overcome in a Wein-Bridge oscillator? (c) What function does the Wein-bridge section have in Wein-Bridge oscillator? (d) Why is the bridge not used to provide phase shift? 10. Sketch the circuit diagram for a Wein-Bridge oscillator that uses a two stage BJT amplifier. Explain the circuit construction and operation. Obtain an expression for frequency of oscillation. 11. Describe a Piezo-Electric crystal as used with electronic circuits. Sketch the crystal equivalent circuit and impedance / frequency graph. Explain the behavior of electronic crystals.
12. Draw the circuit diagrams of (a) a series operated crystal oscillator and (b) a shunt-excited crystal oscillator. Explain the construction and operation of the circuit. UNIT III - LARGE SIGNAL AMPLIFIERS Part - A 1. What is power amplification? Define a power amplifier. 2. What is the need of power amplifier in audio applications? 3. What are the differences between a voltage amplifier and power amplifier? Distinguish between them. 4. Which amplifiers are classified as power amplifiers? Explain the general features of a power amplifier. 5. Explain why a voltage amplifier cannot be efficiently used as a power amplifier, though useful power is developed at the output of voltage amplifier? 6. What are the performance quantities of a power amplifier? Explain them. 7. How do you classify power amplifiers? 8. What is Class-A operation? 9. Explain the Q-point placement in Class-A power amplifier with neat sketches of loadline. 10. What are the merits and demerits of class-a power amplifier? 11. Mention some of the important applications of Class-A amplifier. 12. What is Class-B operation? 13. Explain the Q-point placement in Class-B power amplifier with neat sketches of loadline. 14. What are the merits and demerits of class-b power amplifier? 15. Mention some of the important applications of Class-B amplifier. 16. What is Class-C operation? 17. Explain the Q-point placement in Class-C power amplifier with neat sketches of loadline. 18. What are the merits and demerits of class-c power amplifier? 19. Mention some of the important applications of Class-C amplifier. 20. What is Class-AB operation? 21. Explain the Q-point placement in Class-AB power amplifier with neat sketches of loadline. 22. What are the merits and demerits of class-ab power amplifier? 23. Mention some of the important applications of Class-AB amplifier. 24. What is Class-D operation? 25. Compare the various power amplifier classes with respect to its operating cycle, position of Q-point and efficiency. 26. What are the disadvantages in Series fed, Directly coupled Class-A power amplifier? 27. What are the advantages & disadvantages in Transformer coupled Class-A power amplifier? 28. What is impedance transformation in case of a transformer? Explain the procedure of calculating a reflected load on primary for a step-down transformer. 29. What does the terms complementary and symmetry indicate? 30. What is the difference between class-b and class-ab power amplifiers? 31. Draw the circuit diagram of push-pull amplifier. Explain why even harmonics are not present in a pushpull amplifier. Give two additional advantages of this circuit over that of a single transistor amplifier.
32. What are the advantages of push-pull circuit over that of a single transistor amplifier? 33. Which power amplifier gives minimum distortion? Why? 34. For the analysis of power amplifier why graphical techniques are used? 35. What is thermal resistance? Explain the thermal-electrical analogy related to a transistor with heat sink. 36. What is heat sink? What is its function? 37. Show mathematically, how class-b push-pull amplifier eliminates even-ordered harmonics. 38. Explain second and third harmonic generation in power amplifiers. 39. What is non-linear distortion in power amplifiers? Part B 1. Explain the working of Series fed, Directly coupled Class-A power amplifier with the help of a neat circuit diagram. Give the expression for dc power input, ac power output and efficiency? 2. Explain the working of Transformer coupled Class-A power amplifier with the help of a neat circuit diagram. Give the expression for dc power input, ac power output and efficiency? 3. Explain the working of Class-B power amplifier with the help of a neat circuit diagram. 4. What is crossover distortion? How can it be eliminated? 5. Explain the working of Class-B Push-Pull power amplifier employing input and output transformers with the help of a neat circuit diagram. Discuss its advantages and disadvantages. 6. Draw the circuit diagram of Class-AB complementary / symmetry power amplifier with its loadline and explain its operation. Give the expression for dc power input, ac power output and efficiency? 7. (a) Explain the working of Class-C power amplifier with the help of a neat circuit diagram. What is its drawback? Where can you use Class-C amplifiers? (b) In class-c circuit the output current flows for a period less than 180o of the input signal. How the signal is reconstructed at the output? 8. Write a short note on Class-D amplifier. 9. (a) What is harmonic distortion? How the output signal gets distorted due to the harmonic distortion? (b) What is the meaning of % harmonic distortion? How the total harmonic distortion is calculated? UNIT IV -TUNED AND WIDE BAND AMPLIFIERS PART A 1. What is meant by tuned amplifiers? 2. What are the classifications of tuned amplifiers? 3. Draw the tuned circuit? 4. What are the classifications of tuned amplifiers according to the coupling used to calculate the stages of multistage amplifiers? 5. What is single tuned amplifiers? 6. What is double tuned amplifier? 7. What is stagger tuned amplifiers? 8. What are the advantages & disadvantages of the tuned amplifiers?
9. What is gain bandwidth product? 10. Discuss the instability of tuned amplifiers? 11. A high Q circuit has ---------- selectivity. 12. What is meant by quality factor? 13. Give the expression for the quality factor? 14. Give the 3-dB bandwidth for resonant circuit? 15. Compare single-tuned and double-tuned amplifier? 16. Draw the output response of double tuned amplifier? 17. What is meant by video amplifier? 18. What are the designs considerations to be followed for video amplifier? 19. Draw the frequency response of video amplifier? 20. What are the features of CA3040 video amplifier? PART B 1. Explain the working of single tuned amplifier with neat diagram? 2. Explain the working of double tuned amplifier with neat diagram? 3. With a neat sketch explain the working of stagger tuned amplifier? 4. Differentiate between single, double and stagger tuned amplifier? 5. Explain the working of CA3040 with neat circuit diagram? 6. Explain the working of MC1550 video amplifier with neat circuit diagram? 7. What is a cascade video amplifier? Explain the circuit with neat circuit diagram? UNIT V-PULSE AND WAVESHAPING CIRCUITS PART A 1. What is multivibrator? 2. How multivibrators are classified? 3. What is astable multivibrator? 4. What is bistable multivibrator? 5. What is Monostable Multivibrator? 6. Draw the output waveforms of astable multivibrator? 7. Draw the output waveforms of bistable multivibrator? 8. Draw the output waveforms of monostable multivibrator? 9. What is the function of commutating capacitor? 10. Write the applications of bistable, monosatble, astable multivibrator? 11. Draw the circuit of Schmitt trigger? 12. What are applications of Schmitt trigger? 11. What is lower threshold point in Schmitt trigger? 12. Which circuit is used as an amplitude comparator? 13. Draw the output waveforms of Schmitt trigger? 14. Which multivibrator is also known as free running multivibrator? Why? 15. What is meant by voltage-comparator?
16. Draw the circuit diagram of current switch comparator? 17. What is current time base generator? give the types? 18. What is voltage time base generator? Give the types? PART B 1. With neat circuit diagrams and waveforms describe the operation of monostable multivibrator and derive the expression for pulse width. 2. Describe the operation of fixed bias bistable multivibrator with neat diagrams 3. Explain the working of self biased binary with the help of neat circuit diagram. 4. With complete circuit explain the operation of a Schmitt trigger circuit 5. With neat circuit diagrams and waveforms describe the operation of Collector coupled Astable multivibrator and derive the expression for Time period of the output waveform. 6. Explain the working of Miller time base generator? 7. Explain the working of Bootstrap time base generator? 8. Explain the working of current time base generator? 9. Explain voltage comparator circuits with neat diagrams?