VIVA-questions semi conductor

8/12/2019 VIVA-questions semi conductor

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ELECTRONIC ENGINEERING I Lab VIVA Questions

SEMICONDUCTOR PHYSICS:

1. What are intrinsic and extrinsic semiconductors?2. List the properties of semiconductors.

3. Draw the energy band diagram of germanium and a metal.

4. What do you mean by alance electron?!. "ow drift current is produced?

#. Define $electron %olt&.

'. (he relationship between field intensity and potential is gi%en by )))))))))))))).

*. What is the %alue of +xample for ,e and -i at room temperature 3//0?. Draw the energy band diagram of a semiconductor and conductor.

1/. What is drift current? pon what factors it depends?

11. Why do we go for +xtrinsic semiconductor?12. "ow is extrinsic semiconductor formed?

13. List the penta%alent and tri%alent impurities.

14. What is diffusion current?1!. Distinguish between Drift and Diffusion current.

1#. Differentiate insulators semiconductors and metals.

1'. +xplain what is hole. "ow do they mo%e in intrinsic semiconductor?1*. What does doping in semiconductor mean?

1. +xplain ma5ority and minority carrier in semiconductor?

2/. What is fermi le%el? "ow is it useful in the analysis of semiconductors?

21. Define the term&s conducti%ity and mobility in semiconductor.22. -tate +instein relationship.

23. Define carrier lifetime.

24. -tate mass action law.2!. Write down the expressions which are used for finding the electron and hole

concentration.

2#. Deri%e the continuity e6uation from the first principle.

2'. +xplain drift and diffusion current and write the expressions for total 7urrent densitydue to holes and electrons

2*. Deri%e the e6uation for the concentration for holes and electrons.2. +xplain in detail the classification of solids with energy band diagram.

3/.+xplain about8

a Donor atoms b 9cceptor atoms c :ntrinsic semiconductors d ;


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1/. What is the effect of temperature on =; 5unction diodes?

1. What is the need for doping?

2. "ow depletion region is formed in the =; 5unction?

3. What is lea0age current?

4. What is brea0 down %oltage?!. What is an ideal diode? "ow does it differ from a real diode?

#. What is the effect of temperature in the diode re%erse characteristics?'. What is cut


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IV! %&T"CE *on'i(u)ation

1. What is the range of E for the transistor?

2. What are the input and output impedances of 7+ configuration?

3. :dentify %arious regions in the output characteristics?4. what is the relation between and E

!. Define current gain in 7+ configuration?

#. Why 7+ configuration is preferred for amplification?

'. What is the phase relation between input and output?*. Draw diagram of 7+ configuration for =;= transistor?

. What is the power gain of 7+ configuration?1/. What are the applications of 7+ configuration?

1. What is the significance of arrow in the transistor symbol?2. Define current amplification factor?

3. What is the function of a transistor?

4. ,i%e the doping le%els and the width of the layers of BG(.

!. (wo discrete diodes connected bac0


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. What is the a%erage %alue of oIp %oltage for "WA?1/. What is the pea0 factor?

1. Why are rectifiers used with a filter at their output?

2. What is the %oltage regulation of the rectifier?3. What is the ideal %alue of regulation?

4. What does no load condition refer to?

!. What are the ad%antages of bridge rectifier?

#. What are the ad%antages and disad%antages of capacitor filter?

'. What are the applications of rectifiers?*. What is the regulation for ai "alf < wa%e circuit ii >ull


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1!. What are the parameters of >+(?

4. Why thermal runaway does not occur in >+(?

!. What is the difference between K->+( and >+(?

1. What is trans conductance?2. Why current gain is important parameter in BG( whereas conductance is important parameter in

>+(?

3. What is pinch off %oltage

4. "ow can a%alanche brea0down be a%oided in >+(!. Why does >+( produce less electrical noise than BG(.

I1! CE A-,0i'ie)

1. What is phase difference between input and output wa%eforms of 7+ amplifier?

2. What type of biasing is used in the gi%en circuit?3. :f the gi%en transistor is replaced by a p


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4. What is holding current?!. What are the important type&s thyristors?

#. "ow many numbers of 5unctions are in%ol%ed in -7A?

'. What is the function of gate in -7A?*. When gate is open what happens when anode %oltage is increased?

. What is the %alue of forward resistance offered by -7A?

1/. What is the condition for ma0ing from conducting state to nonormula for the intrinsic stand+( and G(?

'. :s G( is used an oscillator? Why?

*. What is the Aesistance between B1 and B2 is called as?

. What is its %alue of resistance between B1 and B2?1/. Draw the characteristics of G(?

+xperiment N 1

-tudy of 7A

1. "ow do you measure fre6uency using the 7A?

2. 7an you measure signal phase using the 7A?

3. -uggest a procedure for signal phase measurement using the data from 7A?

4. 7an you comment on the wa%elength of a signal using 7A?

!. "ow many channels are there in a 7A?

#. 7an you measure D7 %oltage using a 7A?

+xperiment N 2

7omparison of diodes

1. What is doping?

2. What is cut


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. What is the effect of temperature on diode re%erse characteristics?

1/. What is an ideal diode and how does it differ from a real diode?

11. What is meant by a diode model? ;ame any two models.

12. What is diode e6uation?

13. What are the applications of a diode?

14. What is =:? What is brea0down %oltage?

1!. What is the effect of temperature on =; 5unction diodes?

1#. :f the impurity concentration is increased how does the depletion width get effected?

1'. What is @ener diode? "ow is it different from an ordinary diode?

1*. What are Cener and 9%alanche brea0down mechanisms?

1. What type of biasing must be used when a Cener diode is used as a regulator?

2/. What is the region of operation in which the Cener diode wor0s?

21. What types of temperature coefficient does the Cener diode ha%e?

22. 7an Cener be used as a rectifier?

23. What are the ad%antages of the Cener diode?

24. What is the application of Cener diode?

2!. What are the factors that affect the stability?

2#. Does the dynamic impedance of a Cener diode %ary?

2'. Define oltage Aegulator.

2*. +xplain how the Cener diode acts as a %oltage regulator.

2. Differentiate between the line and load regulation?

3/. "ow can the brea0down %oltage of a particular diode be controlled?

31. What type of temperature coefficient does the 9%alanche brea0down ha%e?

32. By what type of charge carriers the current flows in Cener and 9%alanche brea0downdiodes?

+xperiment N 3

"alfull


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4. 7ompare half


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1!. Why is the 7+ configuration more important than the other configurations?

1#. Why high input resistance and low output resistances are preferred in transistor circuits?

1'. :n saturation region of 7+ configuration as :Bincreases what happens to :7.

1*. What are the %alues of B+cut


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'. :s G( used as an oscillator? Why?

*. What is the resistance between B1 and B2 called?

. What is it %alue of resistance between B1 and B2

1/. Draw the characteristics of G(.

11. What is meant by the term brea0 o%er %oltage in -7A?

12. "ow many 5unctions are there in -7A?

13. Define holding current.

14. +xplain -7A >iring.

1!. ;ame few applications of -7A.

1#. What is meant by holding %oltage and holding current in -7A?

1'. :s brea0 o%er %oltage in -7A a function of gate current? Discuss.

1*. ;ame %arious regions of -7A characteristics.

1. ;ame different terminals of -7A.

2/. What are the specifications of -7A?

21. :n which state -7A turns on conducting state to bloc0ing state?

22. What is the function of gate in -7A?

23. When gate is open what happens when anode %oltage is increased?

24. What is the %alue of forward resistance offered by -7A?

2!. What is the condition for ma0ing from conducting state to non


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1/. What is the effect of coupling capacitor on low fre6uency response?

+xperiment N 1/

+mitter >ollower N 77

1. What are the features of 77 amplifier?

2. Does phase re%ersal exist in 77 amplifiers?

3. Why 77 amplifier is also called as emitter follower?

4. What are the applications of an emitter follower?

!. 7ompare the input and output resistances and performance of all the 3 configurations.

#. "ow do the biasing resistor %alues affect the input resistance of the circuit?

'. Draw the h


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11. 7ompare n


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2

P lnd T A Pd od i

V V N NkTr V

I I q n

= = =

/ 1/ 2'3P 1.#/2 1/T C q C = + =

Diode drop changes/Q 2.2 Imv C, (eaage current sI doubles on

/1/ C

Diffusion capacitance is ddq

cdv

= of forward biased diode it is I

)ransition capacitance TC is capacitance of reverse biased diodenV 1 12 3n to=

*E")+F+E*

"-!/*++-0

12 F2 ") F2 &*

DCV mV

2 mV

2 mV


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rmsV 2m

V2

mV

2mV

*ipple factor

1.21 /.4*2 /.4*2

*ectification efficiency

4/.#R *1R *1R

PIV

!ea +nverse VoltagemV 3 mV mV

UNIT III :: FILTERS

1armonic "omponents in F2 -utput, /2 4 1 1

cos 2 cos 4 .....3 1!

mVv wt wt

= + +

"apacitance +nput Filter,

+nductor +nput Filter,

"ritical inductance is that value at which

diode conducts continuously, in or half cycle.

(" F+()E*,

2

2

12 LC

=

or

1.2 !/ .for H L in H C in !

LC

F+()E*,

*" F+()E*,

(" (/DDE*,

1 2

1 2

2. . .....

3

n

n

cc c

L L L

"" "

" " "=


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E0E* D+-DE

E0E* *E56(/)-*

Pi

s i

s

V VI V V

#

= >>

Vr

I=

UNIT - IV

&7), &ipolar 7unction )ransistor has 3 7unctions8 &E, &"

"omponents of current are n$ p$ I I at $% 9unction wheren$ n$

n$ p$ $

I I

I I I= =

+

= Emitter efficiency, S ncn$

I

I = transportation factor.

I P I%$ f & %C r &= =

F2D &ias 0ormal

Diode :.; V Drop

*everse &ias

e & cI I I= +

Pc c

e &

I I

I I = =

Doping Emitter 1ighest

&ase (owest

e c &I I I> >


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(eaage currents 8 C%' C$' $%'I I I ( )1C$' C%'I I= +

< "onfigurations are used on &7), "E, "& = ""

"ommon Emitter, V+ characteristics

C$

CV

%

I

I =


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/P ce%$

i ie e ce

% c

VV# ( r r r

I I

= = = = =

AC Equivalent Ciruit

"--0 &/E V+ "1/*/")E*+)+"

P1

C

$

I

I

= =

+

P PVC%

C c&$%i& e f& c&

$ e c

I VV( r ( r

I I I

= = = =

COM!ARISON

&E &"

/)6*/)+-0 f>b f>b

/")+VE f>b r>b

"6) -FF r>b r>b

/!(+F+E* "-!/*+-0

"& "E ""

i# (-2 ED 1+51

IA IA 1+

VA 1igh 1igh ?@

o# 1igh 1igh low

AC Equivalent Ciruit


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UNIT - V

hA parameters originate from e#uations of amplifier

2 2 / 2i i i r f iv ( i ( v i ( i ( v= + = +

i iv i are input voltage and current

2 2v i are output voltage and current

i( input impedance ie i& ic( ( ( ( ) 1e e er r r +

f( current gain fe f& fc( ( ( ( ) 1 +

r( reverse voltage transfer re r& rc( ( (

o( output admittance oe o& oc( ( (

F+E(D EFFE") )*/0+)-*, FE) is 6nipolar Device

C"n#truti"n n-C$annel %-C$annel

%ource, 5%5ate, D%Drain

5 7unction in *everse &ias /lways

gsV "ontrols 5ate 2idth

V+ "1/*/")E*)+"


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Tran#&er C$arateri#ti# Ciruit F"r'ar( C$arateri#ti#

hocley E#uation

2

1 gs

d dss

p

VI IV

=

, / 1 gs

m m

p

Vg gV

=

-FE)8 etal -Bide emiconductor FE), +5FE)

De%leti"n T)%e M"#&et S)*+"l# En$ane*ent M"#&et

Depletion )ype -FE) can wor width /gsV > and /gsV

VIVA-questions semi conductor

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