EC151-Electronics Engineering, 2007 Question Paper

Anna University, Chennai.

B.E. DEGREE EXAMINATION, April/May 2007

Second Semester

Civil Engineering

EC 151 — ELECTRONICS ENGINEERING

Time : Three hours

Maximum : 100 marks

Answer ALL questions.

PART A — (10 ? 2 = 20 marks)

1. Distinguish between Intrinsic and Extrinsic Semiconductors.

2. What is Zener effect? Explain briefly.

3. What are the special features of CC and CB configurations in terms of ‘‘h’’ parameter values?

4. Draw the characteristics of UJT and identify the negative resistance region in it.

5. Write the expression for the ripple factor for a full wave rectifier with L section and Pi section filters.

6. Write down various types of feedback amplifiers.

7. How OP–AMP can be used as a stable multivibrator? Draw necessary circuit diagram.

8. What will be the output of OP–AMP differentiator for a square wave input? Draw necessary 



wave-forms to justify your answer.

9. How to get NOR from NOT and OR? Also give the truth table for NOR.

10. List out any two types of A/D conversions possible.

PART B — (5 ? 16 = 80 marks)

11. (i) Derive the expression for voltage gain, current gain, input impedance and output impedance for 

a typical CE amplifier in terms of ‘‘h’’ parameters. (8)

(ii) Draw the circuit of simple Zener Regulator and derive the expression for AND gate. (8)

12. (a) (i) Using energy band diagram, explain the functioning of a semiconductor PN junction diode 

under various bias conditions. (8)

(ii) On what basis, solids are classified as conductors, semi–conductors and insulators? Explain. (8)

Or

(b) (i) How to get a P–type semiconductor from intrinsic one? Explain. (8)

(ii) Define and derive the expression for diode resistance. (8)

13. (a) (i) Derive the expression for the current stability factor S for fixed bias and collector to base bias

 in CE configuration. (8)

(ii) Explain the purpose and working of DIAC. (8)

Or

(b) (i) Draw the basic structure of an N–channel JFET and explain its principle of working with necessary 

characteristic curve. (8)

(ii) Under what circumstances, a TRIAC can be used? Explain its principle of working with necessary 

characteristic curves. (8)

14. (a) (i) Draw the circuit of a mono-stable multi-vibrator using OP–AMP and explain its working. (8)

(ii) How OP–AMP can be used as an Integrator? Explain in detail. (8)

Or

(b) (i) Explain with diagram an OP–AMP adder and sign changer. (8)

(ii) With diagram, explain the principle of working of active lowpass filter using OP–AMP. (8)

15. (a) (i) What are Universal gates? Explain their principle of working with necessary truth–table. (8)

(ii) With a neat diagram, explain the principle of working of a typical digital computer. (8)

Or

(b) (i) How a Full–Adder can be constructed using Half–Adder? Explain with necessary diagram and 

truth–table. (8)

(ii) With a diagram, explain the working of D/A converter using R–2R network. (8)

                                                            ______________________________

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