Mahatma Gandhi University (MGU) 2008 B.Tech Electronics and Communications Engineering , - Question Paper

B.TECH DEGREE EXAMINATION, MAY 2008

3rd Semester
SOLID STATE ELECTRONICS (L A S)
( Supplementary, Improvement)

Time: three hours Maximum:100 marks

Part A

ans all ques. briefly. every ques. carries four marks.

1. Sketch the Fermi level in energy band diagram of an intrinsic semiconductor and compare with that of the extrinsic kinds.
2. Distinguish ranging from direct and indirect band gap semiconductors.
3. Write the Einstein relation and discuss.
4. With a neat diagram, discuss the Quasi Fermi level.
5. Describe the working of photodiode.
6. What are the advantages and disadvantages of LED?
7. describe how a transistor is biased in active region.
8. Define emitter efficiency and base transport factor and relate them.
9. Explain pinch-off and threshold voltages.
10. Compare n MOS and p MOS.


PART B
ans either a or b of every module. every full ques. carries 12 marks.

MODULE I
11. (a) Derive the expression for the majority and minority carrier concentraions in an n kind semiconductor. find the expression for its conductivity.
Or
(b) With the help of neat sketches, discuss what is meant by carrier concentration
And Fermi level in intrinsic and extrinsic semiconductors. Derive suitable
Relationship ranging from them.

MODULE 2

12. (a) Sketch the different current componentprofiles in a forward and reverse biased
pn junction diode and discuss.
Or
(b) elaborate the different kinds of breakdown mechanism that occur when a junction is reverse biased ? Differentiate theim qualitatively discuss their significances.

MODULE 3

13. (a) With the help of neat energy band diagrams discuss the working of a tunnel diode. Sketch and discuss the VI characteristics, giving its application.
Or
(b) (i)Derive equations for the capacitance of a varactor diode. What is it's application?
(ii)Sketch and discuss the forward and reverse VI characteristics of a zener diode.

MODULE 4

14.(a) Sketch the diagram showing all the currentcomponents in a pnp transistor biased in the active region and discuss the profiles.

Or
(b) With the help of necessarydiagrams, discuss the amplifying and switching actions performed by the BJT in CE configuration. Show the relationship ranging from Ic, Ib and b in both the cases.

MODULE 5

(a) With the help of constructional diagram , define the working of n-channel JFET. Indicate clearly the ohmic and pinch off regions. discuss the VVR operation and its applications..

Or
(b) With the help of neat constructional diagram and characteristics define the operation of a depletion typeMOSFET. Sketch the charges induced in the different layers clearly. elaborate its merits and demerits compared to JFET?

Earning:   Approval pending.