KARPAGAM COLLEGE OF ENGINEERING(Autonomous)Coimbatore-32.

END SEMESTER EXAMINATIONSM.E (VLSI DESIGN) - Semester-II12P206/12F206- ELECTRONIC DEVICES AND CIRCUITS

Time: 3 HrsMax. Marks: 100Answer ALL questions PART-A(10X2=20 marks)1. What is Static resistance?2. What are the advantages and limitations of LCD?3. Calculate of a transistor when =0.984. Draw the input and output characteristics of a transistor in CE configuration and mark the cutoff, saturation and active regions. 5. What are hybrid parameters?6. State Barkhausen conditions for sustained oscillator?7. Why capacitor filter is not suitable for variable loads?8. What is the advantage of clap oscillator over a colpitts oscillator?9. Compare shunt and series regulator.10. Calculate the value of c that has to be used for the capacitor filter of a full wave rectifier to get a ripple of 0.01%. the rectifier supplies a load of 2 k while the supply frequency is 50 Hz.

PART- B (5X16=80 marks)

11. a) With a neat diagram explain the working of a PN junction diode in forward bias and reverse bias and show the effect of temperature on its V-I characteristics.(16)(OR) b). (i) compare the performance of LED and PN Junction diode.(8) (ii) Write a short note on photodiode.(8)

12. a).Consider A single Stage CE amplifier with RS=1K, R1=50K, R2=2K, RC=1K, RL=1.2K, hfe=50, hie=1.1K, hoe=25A/V and hre=2.5*10-4. Find Ai, Ri, Av=Ai=IL/IS, AVS=VO/VS and Ro. (16)(OR) b) Explain the construction, principle of operation, characterizes and applications of:(i) Opto couplers(8)(ii) Power transistors(8).

13. a) Explain the concept of negative feedback in amplifier. Derive the expressions for voltage gain, input impedance and output impedance.(16)(OR) b) What do you understand by differential amplifiers? Draw the circuit diagram & explain the working of differential amplifier. Explain the circuit operation at CM and DM. (16)

14. a) Draw the circuit diagram and explain the principle of operation of the following oscillator:(i) Wien bridge oscillator(8)(ii) Clapp oscillator(8) (OR)b) (i) Differentiate oscillator with amplifier. (4) (ii) Draw the circuit of a Hartley oscillator and derive the condition for the frequency of oscillation. (12)

15. a) Explain the various filters used in power supplies (16) (OR)c) With a circuit diagram, explain the working of a bridge rectifier. Give the input and output waveforms. (16)

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