# B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011. Third Semester Electrical and Electronics Engineering EE 2203 — ELECTRONIC DEVICES AND CIRCUITS (Regulation 2008) Time : Three hours Maximum : 100 marks Answer ALL questions.      PART A — (10 × 2 = 20 marks) 1. What is meant by dynamic resistance of diode? 2. Differentiate between zener breakdown and avalanche breakdown. 3. Draw the h-parameter equivalent circuit of a CE BJT configuration. 4. What is the application of optocoupler? 5. What is pinch off voltage? 6. Give any two differences between E-MOSFET and D-MOSFET. 7. What are the advantages of differential amplifier? 8. State Barkhausen criteria. 9. Sketch the output waveform for the clipper shown in the figure below. Neglect the drop across the diode. 10. What is intrinsic standoff ratio in UJT? PART B — (5 × 16 = 80 marks) 11. (a) Draw the circuit diagram and explain the operation of full wave rectifier using center tap transformer and using bridge rectifier without center tap transformer. Obtain the expression for peak inverse voltage. (16) Or (b) (i) With neat diagram explain the construction and working of LED. (8) (ii) Explain the working of LCD seven segment display using square wave supply. (8) 12. (a) Draw the circuit for determining the transistor common base characteristics and explain how the characteristics are measured and draw the graphs. (16) Or      (b) For a common emitter circuit draw the h-parameter equivalent circuit and write the expressions for input impedance, output impedance and voltage gain. (16) 13. (a) Draw the circuit diagram of common source FET amplifier and give the design steps to find the component values used in the circuit. (16) Or      <!-- google_ad_client = "ca-pub-1886054018235657"; /* 336x280, created 7/29/11 */ google_ad_slot = "6580165306"; google_ad_width = 336; google_ad_height = 280; //--> (b) Explain the construction and working of enhancement MOSFET and depletion MOSFET. Draw the characteristics. (16) 14. (a) Explain the concept of negative feedback in amplifier. Derive the expressions for voltage gain, input impedance and output impedance. (16) Or      (b) (i) With a neat diagram, explain the construction and working of BJT RC phase shift oscillator. (8) (ii) Explain the construction and working of Hartley oscillator. (8) 15. (a) (i) Explain the construction, equivalent circuit and operation of UJT. Draw the characteristics of UJT. (8) (ii) Explain how UJT is used to generate saw tooth waveform. (8) Or      (b) Explain the operation of collector coupled monostable multivitrator with neat circuit diagram and draw the various waveforms. (16)

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