Osmania University (OU) 2006 B.Sc Electronics ELECTRONIC DEVICES AND CIRCUITS - Question Paper

B.SC. Degree Examination, March- 2006

(Examination at the end of 2nd year)

Electronics

Paper-II ELECTRONIC DEVICES AND CIRCUITS

Time: three hrs Max Marks: 100

PART-A (4x14=56 Marks)

ans ALL ques..

1. (a) describe diffusion constant for holes. discuss the relation ranging from diffusion and mobility. explain the dependence of mobility on doping concentration and temperature.

OR

(b) Describe the construction and working of a zener diode. explain its V-I characteristics. discuss with circuit diagram,how it can be used as a voltage regulator.

2. (a) Draw the hybrid equivalent circuit of a CE amplifier and derive its 4 hybrid parameters.

OR

(b) How amplifiers are classified based on frequency ranges? discuss the operation of 1 of them giving suitable diagram.

3. (a) explain the effect of negative feedback on: (i) Gain (ii) Noise (iii) Bandwidth (iv) Input impedance and (v) Output impedance.

OR

(b) What is multivibrator? Draw the circuit of an Astable multivibrator and discuss its operation.

4. (a) define the experimental setup to draw the output and transfer characteristics of JFET. discuss how FET parameters can be determined from these characteristics.

OR

(b) Explain the construction, working and characteristics of Solar cell and LED.

PART-B (4x 5=20 marks)

ans any 4 ques..

5. Distinguish ranging from an intrinsic and extrinsic semiconductor.

6. How does the reverse saturation current in a PN diode vary with temperature?

7. Explain how a UJT work as a relaxation oscillator.

8. Explain the Darlington pair circuit.

9. Define falpha, fbeta and f T of a transistor.

10. Distinguish ranging from BJT and FET.

11. Draw the circuit of self-bias and discuss.

PART-C (4x 6=24 marks)

ans any 4 of the subsequent.

12. A transistor has ICBO= 48 micro amperes and alpha=0.992. obtain beta and ICEO. Also obtain IC when IB=30 micro amperes.

13. find the relation ranging from Gain with feedback and without feedback.

14. An N- channel JFET has pinch off voltage of – 4.5V and IDSS= nine milli amperes. At what value of VGS in the pinch off reginon will ID equal three milli amperes?

15. Explain the tunnelling phenomenon.

16. Explain the construction and working of Schottkey diode.

17. Find the static and dynamic resistance of a PN junction Ge diode if temperature is 27 degree Celsius and Is=1micro ampere ,for an applied forward bias of 0.2V.

18. A phase shift oscillator uses 3 identical RC parts in the feedback network. The values of components are R=100kohms and C=0.10 microf. compute the frequency of oscillation.

Earning:   Approval pending.