Lecture 1 .pdf

this lecture contain about introduction to electronic circuits

1. Dr. Allam Ameen
Assistant Professor
Egyptian Chinese University, Faculty of Engineering and Technology
Electronics Research Institute, Microstrip Department
Spring 2025
Electronic Circuits
(MCT 123)

2. Introduction
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3. Introduction
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ElectricCircuit
WhatismeantbyElectricCircuit?
Aclosedpathinwhichcurrent
flowsinconductingmaterial.
Currentflowsinpresenceofa
Voltage/Currentsource.
Containspassivecomponentslike
R,L&C.
Elementsofelectriccircuitsare
connectedthroughwires.

4. Introduction
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Types of Resistors
Unit:
Ω(Ohm)

5. Introduction
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Types of Inductors
Unit:
H (Henry)
Types of Capacitors
Unit:
F (Farad)

6. Introduction
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7. Introduction
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ElectronicCircuit
WhatismeantbyElectronicCircuit?
Aclosedpathinwhichcurrentflows
aschargesingas,vacuumor
semiconductormaterial.
Currentflowsinpresenceof
aVoltage/Currentsource.
ContainscomponentslikeDiodes,
Transistorsetc.
Circuit Componentscan be integrated
ona small-sizedchip(Integrated
Circuit(IC)).

8. Introduction
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Whatisinsideyourelectronicdevices?
Your PC

9. Introduction
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Whatisinsideyourelectronicdevices?
Your Phone

10. Introduction
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11. Introduction
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IntegratedCircuits(ICs)

12. Semiconductor devices
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Semiconductordevicesareelectronicdevicesthatare
fabricatedusingsemiconductormaterialssuchasSilicon,
Germanium,andGalliumArsenide.
Semiconductordevicesareavailableasdiscretecomponents.
It canbeintegratedwithalargenumberofsimilardevices
ontoasinglechip,calledanIntegratedCircuit(IC).

13. Semiconductor devices
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14. Semiconductor devices
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15. Semiconductor devices
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Elementsemiconductors
SemiconductorsarefoundingroupIVandneighboringgroupsin
theperiodictable.
ColumnIVSCasSiandGearecalledelementalsemiconductors,because
theyarecomposedofsinglespeciesofatoms.
GewasknownfirstasaSC,thenSireplacedGebecause:
Silicondevicesexhibitbetterpropertiesatroom temperature.
Silicondevicescostmuchlessthananyothersemiconductormaterial.

16. Semiconductor devices
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III -VCompoundSemiconductors
Also,compoundsofcolumn??????????????????andcolumn??????aswellascertain combinations
from????????????and????????????,makeupcompoundsemiconductors.

17. Semiconductor devices
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II-VICompoundSemiconductors
ElementalsemiconductorGewasusedearlierfortransistorsand diodes,andnowSiis
usedforthemajorityofintegratedcircuits.
Whycompoundsemiconductors?
TheyarenormallyusedinspecialapplicationswhereSiisnotapplicable.
ForexampleGaAsisusuallyusedin:HighspeedelectronicsandOptoelectronics

18. Atomic Structure
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Theatomisthesmallestparticleof
anelementthatretainsits
characteristics.
Itconsistsofacentralnucleus
surroundedbyorbitingelectrons(-).
Thenucleusconsistsofprotons(+)
andneutrons(neutral).
Theatomiselectricallyneutral,i.e.
numberofelectrons=numberof
protons=atomicnumber

19. Atomic Structure
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Electronsorbitsthenucleusatdiscreteshells,
eachshellhasaspecificenergylevel.
Theclosertheelectronstothenucleus,the
lesspotentialenergytheyhave,andviceversa.
Ashellcanpossessanumberofsub-shells
whoseenergiesareapproximatelythesame.
Themaximumallowablenumberofelectrons
inthen
th
shellis2n
2
.
Theouter-mostshellisreferredtoasthe
valenceshell,whoseelectronsarereferredto
asthevalenceelectrons.

20. Atomic Structure
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21. Atomic Structure
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Valenceelectronsarethehighestin
energyandthelessboundtothe
nucleus.
Avalenceelectronscanacquire
externalenergy,andescapefromthe
atom.Theescapedelectronis
referredtoasfreeelectronandthe
residualatombecomesa+veion.
Afreeelectroncanloseitsenergy
andfallintothevalenceshellofan
atomandtransformittoa-veion.

22. Atomic Structure
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Allmaterialsaremadeupofatoms.
anatomcanberepresentedbythe
valenceshellandacorethatconsists
ofalltheinnershellsandthe
nucleus.
Theseatomscontributetothe
electricalpropertiesofamaterial,
includingitsabilitytoconduct
electricalcurrent.

23. Atomic Structure
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Allmaterialscanbeclassifiedtothreemainsections.
Conductors
Semiconductors
Insulators

24. Atomic Structure
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Aconductorisamaterialthateasilyconductselectricalcurrent.Most
metalsaregoodconductors.Thebestconductorsaresingle-element
materials,suchascopper(Cu),silver(Ag),gold(Au),andaluminum(Al).
Possess single valence electron and
(+1) core.
Single-element materials.
Examples: copper (Cu)

25. Atomic Structure
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Theband(energy)gapisdefinedasthe
requiredamountofenergyforavalence
electrontoescapefromtheatomand
beingafree(conduction)electron.
Foraconductor:
Zerobandgap.
Easytransitionofelectrons.

26. Atomic Structure
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Asemiconductorisamaterialthatisbetweenconductorsand
insulatorsinitsabilitytoconductelectricalcurrent.Asemiconductorin
itspure(intrinsic)stateisneitheragoodconductornoragood
insulator.Single-elementsemiconductorsarelikesilicon(Si),and
germanium(Ge).
Possess 4 valence electrons and (+4)
core.
Single-element or compounds materials.
Examples: silicon (Si), germanium (Ge)

27. Atomic Structure
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Theband(energy)gapisdefinedasthe
requiredamountofenergyforavalence
electrontoescapefromtheatomand
beingafree(conduction)electron.
Forasemiconductor:
Moderatebandgap.
Possibletransition.

28. Atomic Structure
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Aninsulatorisamaterialthatdoesnotconductelectricalcurrent
undernormalconditions.Mostgoodinsulatorsarecompounds
ratherthansingle-elementmaterialsandhaveveryhighresistivities.
Their valence electrons are tightly bound to
the atoms.
Compounds of more than one element.
Examples: Air, Teflon, andAlumina.

29. Atomic Structure
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Theband(energy)gapisdefinedasthe
requiredamountofenergyforavalence
electrontoescapefromtheatomand
beingafree(conduction)electron.
ForanInsulator:
Largebandgap.
Impossibletransition.

30. Covalent Bonds
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Eachsiliconatomhas4valence
electrons.
Eightelectronsarerequiredto
reachthestateofchemical
stability.
Toachievethisstate,eachatom
sharesitsvalenceelectronswith
fourneighboratoms.
Thiswayofsharingelectronsis
referredtoascovalentbonds,
thatholdtheatomstogether.

31. Covalent Bonds
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Bondingdiagramisshownbeside.
Therednegativesignsrepresentthe
sharedvalenceelectrons.
Thesurroundingatomsareinturn
bondedtootheratoms,andsoon.

32. Covalent Bonds
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Thecovalentbondingof
siliconatomscreatesan
intrinsicsiliconcrystal.

33. Current in semiconductors
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Eachshellaroundthenucleus
correspondstoacertainenergy
bandandisseparatedfrom
adjacentshellsbybandgaps.
Energybanddiagramforan
unexcitedatominapure(intrinsic)
siliconcrystal.
Therearenoelectronsinthe
conductionband.

34. Current in semiconductors
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Generationofanelectron-holepairoccurswhenavalence
electronacquiresexternalenergy,escapesfromtheatom,and
becomesafreeelectron,leavingaholeinthevalenceshell.

35. Current in semiconductors
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Freeelectronsarealsocalled
conductionelectrons.
Recombinationofelectronhole
pairoccurswhenaconduction
(free)electronlosesenergyand
fallsbackintoaholeinthe
valenceshell.
Thisenergylossisreleasedin
theformofphotonemission,
whoseenergy(frequencyor
color)dependsonthebandgap.

36. Current in semiconductors
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Thisenergylossisreleasedintheformofphotonemission,
whoseenergy(frequencyorcolor)dependsonthebandgap.
Whenavoltageisappliedacrossapieceofintrinsicsilicon,twotypes
ofcurrentwillflow:
ConductionBandCurrent
Duetomotionoffreeelectronsintheconductionbandalong
theoppositedirectionoftheappliedelectricfield.

37. Current in semiconductors
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ConductionBandCurrent
Duetomotionoffreeelectronsintheconductionbandalongthe
oppositedirectionoftheappliedelectricfield.

38. Current in semiconductors
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ValenceBandCurrent
Duetomotionofvalenceelectronsinthevalencebandalongthe
oppositedirectionoftheappliedelectricfield.
Thismotionisequivalenttomotionofholesinthevalencebandin
thesamedirectionoftheappliedfield

39. N-Type Semiconductors
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Theconductivityofsiliconcan
begreatlyenhancedbyadding
impurities.
Thisprocessisknownas
dopping.
Basedontheimpuritymaterial,
twotypesofsemiconductors
canbeobtained.
ForN-Type,theimpuritiesare
Sbatoms.

40. N-Type Semiconductors
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Pentavalentimpurityatomswith5valenceelectronsareadded,
suchasarsenic(As),phosphorus(Pb),bismuth(Bi),andantimony
(Sb).
Eachpentavalentimpurityatomgivesrisetoonefreeelectron,
hencetheseatomsarereferredtoasthedonoratoms.
Thermalenergygivesrisetoanumberofelectron-holepairs.
Themajorityofcurrentcarriersareelectronsandtheminority
carriersareholes.Hence,thistypeofsemiconductoriscalledn-
type.
Theconductionbandcurrentisdominant.

41. P-Type Semiconductors
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Theconductivityofsiliconcan
begreatlyenhancedbyadding
impurities.
Thisprocessisknownas
dopping.
Basedontheimpuritymaterial,
twotypesofsemiconductors
canbeobtained.
ForP-Type,theimpuritiesare
Batoms.

42. P-Type Semiconductors
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Trivalentimpurityatomswith3valenceelectronsareadded,such
asboron(B),indium(In),andgallium(Ga).
Eachtrivalentimpurityatomgivesrisetoonehole,hencethese
atomsarereferredtoastheacceptoratoms.
Thermalenergygivesrisetoanumberofelectron-holepairs.
Themajorityofcurrentcarriersareholesandtheminoritycarriers
areelectrons.Hence,thistypeofsemiconductoriscalledp-type.
Thevalencebandcurrentisdominant.

43. P-Type Semiconductors
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