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1. Electronic 1
➢Electronic Materials and Devices
✓ The Atomic Structure
✓ Energy Levels
✓ Classifications of solids in terms of their conductivities
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2. Electronic 1
➢Semi-conductor materials
✓ The N and P Types
✓ Current Distribution / flow in semi-conductor materials
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3. Electronic 1
➢The Junction Diode
✓ The Basic Configurations of the diode –forward and reversed biased
✓ Diode Capacitance
✓ Influence of Temperature on the operation of the diode
✓ Diode Circuit Analysis
✓ The DC and AC resistances of the diode
✓ The diode equivalent models
✓ Power dissipation
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4. Electronic 1
➢Graphical analysis of diode circuits
✓ Dc and AC load lines
✓ The dynamic and transfer curves
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5. Electronic 1
➢ZenerDiodes
✓ Voltage regulators
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6. Electronic 1
➢Other diodes
✓ VaractorDiodes
✓ The Schottkeydiode
✓ Tunnel diodes
✓ Opto-Electronic diodes
✓ Photodiodes
✓ Infrared ( IR ) Emitters .
✓ Light emitting diodes LED ‘s
✓ Solar cells
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7. Electronic 1
➢The Bipolar Transistors
✓ Basic Construction and operation of a transistor
✓ The NPN / PNP Transistors
✓ Amplifying action of the transistor :
✓ The Eber-Moll Transistor Model
✓ The basic configurations transistor circuits ( Common Base , Common
✓ Collector and Common Emitter )
✓ DC Biasing of Transistors
✓ BJT Circuits
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8. Electronic 1
➢The Field Effect Transistor
✓ Basic construction and operation
✓ N and P channel FETs
✓ Enhancement and Depletion MOSFETs
✓ FETs DC analysis
✓ FET circuits
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9. Electronic 1
➢An introduction to Op-Amps and basic circuits
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10. Electronic 1
➢Text Books
✓Electronic Devices and Circuit Theory, Boylestadand Nashelsky,
Prentice Hall
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11. ✓One of the most widely used models which describe the structure and behavior of atoms is
known as the bohrmodel.
✓the atom contains
❖neutrons ( neutral particles, i.e. having no charge)
❖protons(positively charged particles )
❖electrons ( negatively charged = to the protons charge ) orbiting around it,asshown in fig ( 1
).
Fig 1 : The Atom structure
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➢The atomic structure

12. ✓the weight of an atom (called the atomic weight )is roughly equals the combined weights of
the protons and neutrons in that atom
✓the number of electrons ( or protons ) orbiting the nucleus is called the atomic number of
that element
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➢The atomic structure

13. ✓For each atom their exist only a number of orbits( discrete energy levels) at which electrons
may exist , with no two electrons existing at any one energy level.
✓This is called the Pauli's exclusion principle
✓The further the electron away from the nucleus the higher it energy state( in the forms of
kinetic and potential energies )
✓The unit of energy which is adopted in atomic theories is called the Electron volt(eV) ,where
1eV= 1.6 X 10 -19J
✓The electron volt is the amount of energy gained or lost when an electron moves with or
against a potential difference of one volt
✓the atomic structure of atoms ,electrons could not have any value of Electron volts other
than an allowable one
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➢Atoms energy levels

14. ✓Forthepurposeofchemicalbehavior,isitbettertogroupthepossibleenergylevels(or
orbits)towhatiscalledelectronsmainshells(denotedK,L,M,N....,Zwiththek-shellbeing
theclosesttothenucleus)asshowninfig(2).
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➢Atoms energy levels
Fig 2 : Shell energy distribution for a material

15. ✓thenumberofelectronsexistinginthevariousshellsdeterminingthechemicalbehaviorof
thematerial
✓Thefirstshellisconsideredcompletewhenitcontainstwoelectronsandthesecondshellis
completewhenitcontainseightelectrons(2n
2
).
✓Manyofthechemicalandelectricalpropertiesofmaterialsaredeterminedbytheelectrons
existingintheoutershell(calledtheValanceelectrons)
❖thematerialbelongstoaninertgas
✓anelectronexistinginashellfurtherawayfromthenucleus(e.g.avalanceelectron)havea
higherenergyandthusmaybedetachedfromit’srespectiveshellquiteeasierthanelectrons
existingininnershells
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➢Atoms energy levels

16. ✓Whenatomsofthesamematerialarebroughttogether,theatomsbonds(eachatom
attemptstohaveeightelectronsinit'soutershell)witheachotherelectrostaticallybymeansof
oneofthreepossiblemethods:
❖Ionicbondingforces--Valenceelectronsjoinwithothervalenceelectronstofillthelatter
outershell
❖Covalentbondingforces--Valanceelectronsaresharedbetweenmorethanoneatoms
❖Metallicbindingforces--Electroncloud(wonderingelectrons)exertelectrostaticforceson
thepositiveIonsandholdthemtogether(e.g.CUmaterial).
✓Inthiscourseonlycovalentbondingwillbeconsidered,sinceitismostapplicableto
semiconductormaterial.
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➢The case of combination of atoms -in solids

17. ✓Fig3showstheenergybandinmaterials.withineachbandtherearestilldiscrete
permissibleenergylevelsratherthanacontinuouslevel.
✓Theenergybandsclosertothenucleushavelesswidthcomparedwithouterbands,thisis
becauseelectronsassociatedwithinnershellsinteractslesswitheachother,whileValence
electronshavestronginteractionwitheachotherresultinginhighermodificationstotheir
respectiveenergylevels
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➢The case of combination of atoms -in solids
Fig 3 , Energy Bands in a Material

18. ✓thevalencebandwillbeconsideredinthestudyoftheconductionpropertiesofsolid
materials.
✓Thehighestenergybandassociatedwithatomswhicharebroughttogether(solids)is
calledthevalenceband(Fig3),sinceitcontainsthevalenceelectrons
✓abovethevalencebandtheirexistwhatiscalledtheConductionBandwhereelectronsinthis
bandarenotattachedtoanyatomsandarefreetowonderaboutandbeinfluencedby
externalforces
✓BetweenthevalencebandandconductionbandtheirexistaregioncalledtheForbidden
bandwhereelectronscannotexist.
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➢The case of combination of atoms -in solids

19. ✓Electriccurrentcanbedefinedasthemovementofcharges,thustheabilityforelectronsto
movefromthevalencebandtotheconductionbanddetermineit’sconductivity.
✓Aconductor--atroomtemperature,thevalanceandtheconductionbandsoverlapeach
othermakingiteasyforavalanceelectrontoreachtheconductionband(Fig4)
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➢Classifications of solids in term of their conductivity
Classifications of Materials in terms of their conductivities

20. ✓Aninsulator--atroomtemperature,theforbiddenbandissowidethatvalanceelectrons
withouttheapplicationofexternalforces,cannotreachtheconductionband
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➢Classifications of solids in term of their conductivity
Classifications of Materials in terms of their conductivities

21. ✓semi-conductor--atroomtemperature,theirexistaforbiddenbandwithwidthsomewhere
betweenzero(conductor)andverywide(isolator)sothatwithouttheapplicationofexternal
forcesomeelectrons(onlyfew)findtheirwaytotheconductionband
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➢Classifications of solids in term of their conductivity
Classifications of Materials in terms of their conductivities
0.67 eV(Ge)
1.1 eV(Si)
1.43 eV(GaAs)

22. ✓Themostwidelyusedsemiconductorbasematerials,inthemanufacturingofelectronic
devicesarecalledSiliconandgermanium(fourelectronsintheoutershell--eachhasfour
valanceelectrons),withthegermaniummaterialhavingaconductivityatroomtemperature
✓Theatomicnumberofsiliconandgermaniumare14and32electronsrespectively
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➢Semiconductor materials

23. ✓Theatomsofsemiconductormaterial(purestate),saySiliconatoms,formsastrong
crystallinestructure(covalentbonding)witheachother(Fig5)
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➢The N -Type semiconductor material
Fig 5 : The covalent crystalline structure of silicon atoms

24. ✓atroomtemperature,onlysomeelectrons,duetomanufacturingproblems,,fromthe
valancebandmanagetoescapesuchbonds,totheconductionband,creatingsomevacancies
(holes)andresultinginsome(verysmall)currentflowinthematerial
✓Thematerial,inthiscaseiscalledintrinsicmaterial.
✓Theconductivityofsuchmaterialcanbeenhancedquiteconsiderablybyadding(1parttoa1
millions)tothesemiconductormaterialsomeimpuritiesofothermaterial(suchasarsenicor
phosphor)whichhasfivevalanceelectrons
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➢The N -Type semiconductor material

25. ✓Foreachatomofimpuritymaterialonlyfourofthefiveelectroncanformastrongbondwith
thesiliconatomsasshowninfig(6),leavingoneelectronlooselybonded
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➢The N -Type semiconductor material
Fig 6 : Covalent structure of Silicon and Phosphor

26. ✓Effectively,theforbiddenbandisreduced,makingiteasiertoinitiateelectronsflowwith
minimumappliedenergy.
✓Thecompositematerial,inthiscaseiscalledExtrinsicmaterial
✓theimpuritymaterialiscalleddonoratoms,ordonorions(sinceitdonateselectronstothe
siliconmaterial)
✓theelectrons,ingeneral,formsthemajoritycarrier
✓theholesarecalledtheminoritycarriers.
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➢The N -Type semiconductor material

27. ✓Adding,impuritymaterialswiththreevalenceelectrons(boron)resultsinamaterialthat
hasmanyvacancies(holes)forelectrons(netpositivecharge)asshowninfig(7)
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➢The P -Type semiconductor material
Fig 7 : Covalent structure of Silicon and Boron

28. ✓Thecompositematerialisnowcalled,P-typeextrinsicmaterial.
✓theimpuritymaterialiscalledacceptoratoms,oracceptorions(sinceitacceptselectrons)
✓positivechargesformsthemajoritycarriers,whereasthesmallnumberoffreeelectrons
existinginthematerialiscalledMinoritycarriers.theholesarecalledtheminoritycarriers.
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➢The P -Type semiconductor material

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➢The P –Type and n-Type semiconductor material

30. ✓Thecurrentflowinsemiconductormaterialcanbeachievedinoneoftwoways:
❖Driftcurrent
❖Diffusioncurrent
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➢Current flow in semiconductor materials

31. ❖Driftcurrent:-thecurrentflowisproducedwhenapotentialdifferenceisappliedacrossthe
material,whichcausesageneraldriftofelectronserratically(duetocollisionsencountered
withotheratoms)throughthematerialtowardsthehigherpotentialside(thepositiveend)Fig
8.
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➢Current flow in semiconductor materials
Fig 8 : Drift Current as a result of applying external energy

32. ❖Diffusioncurrent:-producedwhen(withouttheapplicationofexternalenergy)a
concentrationofcarriersisintroducedtothematerial(justasaddingadropofinktoaglassof
water)Theconcentrationofchargesinonepartofthematerialcauses(duetoapotential
gradient)thechargesinthehigherconcentrationareastomove(diffuse)towardsthelower
concentrationarea,producingthediffusioncurrent
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➢Current flow in semiconductor materials

33. ✓N-Typematerialhaselectronmajority(positiveions)andholesminority
✓theP-Typematerialhasholesmajority(negativeions)andelectronsminority.
✓Whenthetwomaterialsarebroughttogether,asshowninfig(9),andatroomtemperature
,someoftheelectronsformtheN_Typematerialmigrate(diffuse)intotheP-Typematerial
acrossthedividingline(Junction)neutralizingatomsintheP_regionnearthejunction.
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➢Semiconductor device -The PN Junction
The Depletion layer created as a result of and N and P layers are brought together

34. ✓AstheN_regionnearthejunctionlooseselectrons,thenumberofpositiveionsincreasesinthat
regionuntilastagewheretherepellingelectrostaticforcesbetweenthepositiveionsandthe
incoming(fromtheP-Typematerial)holesactstostopthemigrationoftheholes
✓astheP-regionnearthejunctionloosesholes,thenumberofnegativeionsincreaseinthatregion
uptoastagewhererepellingelectrostaticforcesbetweenthenegativeionsandtheincoming
electronsactstostopanyfurthermigrationofelectronsacrossthejunction
✓anareaiscreatednearthejunctionwhichhasnochargecarriers.Thisiscalledthedepletion
layer
✓Theenergyassociatedwiththedepletionlayerformabarrier(equivalenttoasmallpotential
difference,0.3vforgermaniummaterialand0.7vforsiliconmaterial)
✓electronorholehastogatheranenergylevelabovethatofthebarriertomakethejumpacrossthe
junction
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➢Semiconductor device -The PN Junction

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➢Semiconductor device -The PN Junction

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➢basic connections of the Junction diode
✓There are two basic connections for the diode :
❖The reversed biased connections
❖Forward biased connection

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❖The reversed biased connections
✓Fig (10) shows the reversed bias connection
✓The positive terminal of the battery attracts the electrons ( the majority carriers ) in the N-Type
material
✓the negative battery terminal attracts the holes ( also the majority carriers ) from the P-Type material
✓widening the energy barrier and making it extremely hard for an electron or a hole to make a jump
across the junction . i.e. there is no current flow across the junction due to the majority carriers

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❖The reversed biased connections
✓However , some very small current will flow due to the presence of minority carriers in both N and P
Types materials .
✓This current is of the order of few Nanoampsfor silicon material and few Microampsfor Germanium
material
✓both types of materials the current stays constant (limited numbers of minority carriers ) as the
applied voltage is increased up to a stage , called break down voltage , which will be dealt with later ,the
reverse current , suddenly , increases .

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❖The Forward biased connection
✓The positive and negative terminals of the battery causes the electrons ( of the N-Type material ) and
holes ( of the P-Type material ) to move towards each others
✓effectively reducing the energy barrier and causing a large current flow across the junction
✓The higher the applied voltage , the larger the current flow across the junction ( majority carriers increases ) .
✓Fig (11) shows the forward biased connection for the

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❖The Forward biased connection
✓Fig 12 shows the current / applied voltage
relationship for the junction diode

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❖The Forward biased connection
✓Fig 12 shows the current / applied voltage relationship for the junction diode

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❖The Forward biased connection
✓the net forward diode current can be represented by the following equation:
VD/nVT
ID= IS(e -1)
n is a constant between 1 and 2 ( for this course this constant is taken to be 1 ).
VT is a volt-equivalent of temperature and is equals to kT/q , k is a constant = 1.38 X 10 -23 J/K , T is the
temperature in Kelvin’s (Tk=TC+273) and q is the charge of electron = 1.6 X 10 -19 C
Is isreverse saturation current
The applied forward-biased voltage across the diode

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❖The Forward biased connection
✓Example :-At a temperature of 27
o
C (common temperature for components in an enclosed operating
System, determinthe thermal voltage V
T
T=273+27=300 K
K= = (1.38x10
-23
J/K)
Q= 1.6x10
-19
V
T=K*T/Q= (1.38x10
-23
J/K) *300/(1.6x10
-19
)
V
T=25.875 mV

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❖Effect of temperature on the operational characteristics of the diode.
✓increasing the temperature of semiconductor materials causes the generation of more electrons/ holes
pairs ( minority carriers )
✓the increased electron/hole pairs acts to reduce the depletion layer width and subsequently reduce the
forward voltage needed to produce a given forward current value
✓The increased minority carriers also causes an increase in the reverse leakage current as well as an
increase in the avalanche breakdown voltage of the diode

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❖Effect of temperature on the operational characteristics of the diode.
Fig (13) illustrate the effect of temperature on the I -V relationship.

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Diode capacitance.
✓PermittivitY(8.85X10E-12)
✓The space charged region (depletion layer) acts as an insulator in ordinary capacitance (potential
difference across it)
✓As the diode is reversed biased, the depletion layer is widened and capacitance (called transition or
depletion capacitance) is decreased
✓when the diode is forward biased the depletion layer is reduced causing an increase in the capacitance (
called the diffusion capacitance )as shown in fig (14)
Fig 14 : The variation of Capacitance for a Diode

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➢Diode Circuits Analysis
❖For a given diode the D.C (static) resistance R dc is written as R dc = VD/ID
✓The D.C Resistance of a diode
❖In general, the DC resistance of the diode in the reverse direction is very large (typically 5 M ohms)
❖the DC resistance of the diode in the forward direction is relatively low (typically 200 ohms).

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➢Diode Circuits Analysis
✓The D.C Resistance of a diode

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➢Diode Circuits Analysis
❖Because of the nature of varying signal (AC) the AC resistance of the diode can be evaluated as follows:-
1-For small signals (small variations) the AC resistance of the diode is given by Rac=d VD /d ID
evaluated at operating point Q , as shown in Fig (15) (average)
✓The AC diode resistance
Rac= = VT/ID , at Q point
at room temperature , 25 degrees , VT = 26 mV i.e. at room
temperature Rac= 25 mV / ID , at Q point
Rac= (25 mV/ID )+ RB (resistance of wires)

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➢Diode Circuits Analysis
1-For large signals the average AC resistance of the diode is given by Rac=delta VD /delta ID
Where delatVD is the difference between the maximum and minimum values of input voltages.
✓The AC diode resistance

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➢Diode Circuits Analysis
✓The AC diode resistance

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➢Diode Circuits Analysis
the diode characteristics may be simplified as shown in Fig
✓The diode equivalent circuit

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➢Diode Circuits Analysis
✓The power dissipation of the diode is simply calculated from the following equation:
The power of the diode PD = VD X ID
WhereVDandIDarethecurrentthroughthediodeandthevoltageacrossit.
✓thehigherthePD,thehigherthetemperatureofthejunctionofthediodeandifthePDisallowedtogo
aboveaspecifiedlevel,thejunctionmaybedamagedpermanently
✓thejunctiontemperatureisinfluencedbythesurroundingtemperature,TS.
✓Power dissipation in P-N diodes

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➢Diode circuits and applications
❖The D.C Load Line
▪consider the following circuit
▪using Kirchhoff Voltage Law
▪the above equation is that of a straight line ( with a slope of -1/R ) which when plotted on the same
axes as that for the V,I characteristic of the diode would yield an intersection point called the
operating point Q
▪the values of VDQ and IDQ may be obtained directly from the above graph . Similar method
may be adopted for the reversed biased case

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➢Diode circuits and applications
❖The D.C Load Line

56. An-NajahNational University
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➢Diode circuits and applications
❖The D.C Load Line

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➢Diode circuits and applications
✓Diode circuits A B
12V
5K
10K
12V
Since point A has a higher potential than point B , then the diode may be replaced by
it’s equivalent switch component
I=12/15K=0.8 mA
I=(12-0.7)/(15K)= 0.75 mA

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➢Diode circuits and applications
✓Diode circuits A B
12V
5K
10K
12V
Since point A has a lower potential than point B , then the diode may be replaced by it’s
equivalent switch component (open circuit)
I=0
V across the diode = 12 V

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➢Diode circuits and applications
✓Diode circuits

60. An-NajahNational University
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➢Diode circuits and applications
✓Diode circuits

61. An-NajahNational University
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➢Diode circuits and applications
✓Diode circuits

62. An-NajahNational University
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➢Diode circuits and applications
✓Diode circuits

63. An-NajahNational University
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➢Diode circuits and applications
✓Diode circuits

64. An-NajahNational University
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➢Diode circuits and applications
✓Diode circuits

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➢Diode circuits and applications
✓Diode circuits
we need to determine whether the diode is forward or reversed biased . One method is to
remove the diode ( replacing it with a short circuit ) and solve the circuit to determine
the direction of current flow in that short circuit and based on the result we may proceed
to replace the diode with it’s respective equivalent switch status ( open or closed )12V
5K
4K6K
10V

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➢Diode circuits and applications
✓Diode circuits
✓replacing the diode with it’s equivalent switch and applying conventional circuit analysis
would yield the required results

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➢Diode circuits and applications
✓Diode circuits
✓Digital circuitA
B Q
A B Q
5V
0V 0V
0V
0V
5V
5V
5V 5V
0V
5V
5V
1K
For projecting
diodes
✓replacing the diodes with their equivalent circuits yield the exact function of an “OR” gate

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➢Diode circuits and applications
✓Diode applications
▪arectifiercircuit,asthenameimplies,rectifies(ironout)thevaryinginputsignaland
producesanoutputwhichhasaDCcomponent
❖Rectifier circuits
▪SuchacircuitisveryimportantinpowersupplycircuitdesignswheretheACsignalis
transformedtoDCandthusmadesuitablesupplyforelectroniccircuitswhichfunction
usingDConly
▪In this section we will consider the half and full wave rectifier circuits

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➢Diode circuits and applications
✓Diode applications
▪Thehalfwaverectifier❖Rectifier circuits
consider the circuit given in Fig 23 ,and if Vin = Vmaxsin(wt),and assuming the diode to be ideal , then
the output waveform will be as shown

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➢Diode circuits and applications
✓Diode applications
▪Thehalfwaverectifier❖Rectifier circuits
consider the circuit given in Fig 23 ,and if Vin = Vmaxsin(wt),and assuming the diode to be ideal , then
the output waveform will be as shown

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➢Diode circuits and applications
✓Diode applications
▪Thehalfwaverectifier
❖Rectifier circuits
✓The part of the waveform between 0 and 180 degrees has a mean value( DC or average )given by the
following equation :
Vmean. π= ∫ VmaxSin(wt) . d(wt)
i.e. Vmean= 0.637 Vmax
✓and for a full cycle , i.e. between 0 and 360 degrees ,and since the mean value for the part of the
waveform between 180 and 360 degrees equals to zero , it follows that the mean value for the complete
waveform equals :
(0.637+0)Vmax/2 = 0.318 Vmax
✓If the forward voltage for the diode VT is taken into account ,then the output while the diode is
conducting will be decreased by 0.7 V ( 0.2 for germanium )

72. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
▪Thehalfwaverectifier❖Rectifier circuits

73. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
▪Fullwaverectifiercircuit
❖Rectifier circuits
✓Using the circuit .in Fig 24 , and assuming that Vin = Vmaxsin (wt) ,then the positive half of Vin will
find a path through the load and the negative half will also find a path through the load ) although in
the negative direction ) , i.e. the output waveform will be of the form shown in the same Fig

74. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
▪Fullwaverectifiercircuit❖Rectifier circuits

75. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
▪Fullwaverectifiercircuit❖Rectifier circuits

76. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
▪Fullwaverectifiercircuit
❖Rectifier circuits

77. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
▪Fullwaverectifiercircuit
❖Rectifier circuits

78. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Limiting ( Clipping ) Circuits
✓Clipping circuits , acts to limit the input wave form ( by clipping it ) without affecting the remaining
part of the input signal

79. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Limiting ( Clipping ) Circuits
▪Each branch of the circuit can be analyzed separately to arrive to the output waveform .

80. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Limiting ( Clipping ) Circuits

81. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Limiting ( Clipping ) Circuits

82. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Clampers Circuits
▪Clamper circuit is a circuit which clamp ( fix ) an input signal to a d.clevel .
▪The circuit usually has a capacitor , to hold fixed voltages ,as well as a resistive element
▪The R and C values should be chosen so that a large time constant( given by 0.7 RC ) is achieved ,
preventing the fast discharge of the capacitor

83. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Clampers Circuits
▪During the positive part of the input signal, the diode is treated as a short circuit and the capacitor
charges up to the maximum value of the input signal.
▪during the negative part of the input signal , the diode is treated as an open circuit and the resistive
element experience DOUBLE ( -Vin ( held by the capacitor ) -Vin ( of the input signal ) = -2Vin

84. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
✓Diode applications
❖Clampers Circuits

85. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
▪ReferringtothestandardCharacteristicofanordinarydiode,andasthereversedappliedvoltageis
increased,astageisreached,wherebythereversediodecurrentsharplyincreases.Suchavoltage,is
calledthebreakdownvoltage
▪Thebreakdowneffect(lowtohighcurrent)couldbeexplainedintermofTheAvalanchebreakdown(
Minoritycarriersacceleratedbythereversedvoltagetendstoknockotheratomsandgenerateother
electron/holespairs)orthefasterZenerBreakdownorboth
▪Thelatterphenomenaoccursatmuchlowervoltagethanthatfortheavalanchebreakdownandisachieved
asaresultofdopingthesemiconductormaterialswithhigherlevelsofimpuritiesthanordinarydiodewhich
causesamarkedreductionofthedepletionlayer
▪Typicalzenerbreakdownvoltageis5Volts
▪SuchavoltagemaybevariedbychangingthedopinglevelsoftheNandPlayers
✓ZenerDiode

86. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓ZenerDiode
Zenerbreakdown occurs because there is a strong electric
field in the region of the junction that can disrupt the
bonding forces within the atom and generate carriers
The maximum reverse-bias potential that can be applied
before eneteringthe zenerregion is called the peak
inverse voltage (PIV rating) or peak reverse voltage
(PRV rating)

87. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
▪Fig(30)showsatypicalZenerdiodecharacteristiccurve
▪OncetheZenerdiodeconduct,themaximumallowablecurrentislimitedbythepowerratingofthediode
andtheallowablejunctiontemperature,similartoordinarydiodes
▪theZenerimpedance(orresistance)canbecalculatedinsimilarmannertotheconventionaldiodei.e.
deltaV/deltaI
✓ZenerDiode

88. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
▪AnalysisofcircuitscontainingZenerdiodesareperformedinsimilarfashiontothatfortheordinarydiode
i.e.approximatemodelandloadlinemethodsareapplicableinthiscase
▪considerthecircuitof,Fig31andapplyingkirchhoffvoltagelawaroundthecircuit,forthezenerpartof
thecharacteristic,yieldthezenercurrent
▪IZ=[V–VZ]/R
✓Zenerdiode as a circuit element

89. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
▪Avoltageregulatorcircuitisaelectronicnetworkthatregulatethevoltage(keepsthevoltageasconstant
aspossible)suppliedtotheload
▪In the circuit of Fig (32) and if Rloadis allowed to vary between it’s maximum ( infinity value --open cct)
and minimum values ( zero value --short circuit ) the voltage across the load will vary between the following
two limits :
Voutupper = V in
Voutlower = 0 V
i.e. no voltage regulation exist across the load .
✓Zenerdiode applications
✓Voltage regulator

90. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
▪if on the other hand a zenerdiode is introduced to the circuit as shown if Fig (33 ) and using the
approximate equivalent model for the zenerand assuming that the series resistor ( with the power supply )
is used to limit the zenercurrent to 80 mA
✓Zenerdiode applications
✓Voltage regulator

91. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
▪assuming that the zenerdiode is in it’s breakdown region then the voltage
at point A will be held constant and can be used as a reference for other voltage input
✓Zenerdiode applications
✓Voltage Reference Circuit

92. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

93. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

94. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

95. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

96. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

97. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

98. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examples
In the following circuit ; If the power dissipated by the zeneris 50 mWand 500mW when the switch S
at positions 1 and 2 respectively; Determine Rsand RL .

99. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Zenerdiode applications
✓ZenerDiode / Analysis examplesVz=50 V
Vin=200 V
2 K
R
the zenerdiode shown in the following circuit regulate the
voltage at 50 V over a range of diode currents from 5 mA to
40 mA, the supply voltage = 200v .
a-Find the value of R which will allow regulation from load
current I Load = 0 up to the maximum possible current I
max.
b-If R now fixed such that the current passing through it iz
25 mA , find the vlaueof R.
c-Find the limit which the input volageVin may vary without
loss of regulation in the circuit.

100. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓During the positive half-cycle ,Zenerlimiting output voltage to V
Z.
✓During the negative half-cycle, the zenerlimits the output voltage to -0.7 V (forward-biased voltage).
✓Two back-to-back zenerslimit output to ±(V
Z+ 0.7 V) (for positive or negative, respectively.
✓Zenerdiode applications
✓ZenerDiode / Analysis examples

101. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Such diodes are manufactured in a way as to exploit the capacitance effect (works in reverse biased )
✓The doping of the semiconductor materials are affecting the width of the depletion layer and hence
affecting the capacitance of the diode
✓Exact value for such capacitance ( usually in picoFarrad) can be calculated using a number of formulae ,in
terms of the electronic parameters of the diode
✓Typical applications for such diodes are in Voltage oscillator circuits as shown in Fig ( 35 ) .the tuners of
television sets to electronically tune the receiver to different stations
✓VaractorDiodes

102. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓use metallic material such as gold in place of the P-type material
✓Such a structure make use of the free electrons found in the conductor to initiate current flow at very
small forward diode voltage
✓because there is no depletion layer diode response is much faster than ordinary diodes which makes them
ideal for high speed switching applications
✓computer , microwave
✓The Schottkeydiode

103. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Increasing the doping of the semiconductor materials to a certain levels will greatly reduce the depletion
layer width( less than a millionth of an inch )
✓A stage could be reached where by a small forward voltage will cause an appreciable forward current
✓also because of the very thin width of the depletion layer , a small reverse voltage causes a large reverse
current
✓Fig (37) shows a typical tunnel diode I/V response
✓note the kink in the response at a particular forward current . such a kink ( called negative resistance
region ) characterizes this type of diode
✓Because of the very small width of the depletion layer ,
the diode response is very fast and thus , as in the case of the
schottkydiode , it can be used for high speed switching applications
✓Tunnel diodes

104. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Photodiodes
✓Infrared ( IR ) Emitters
✓Light emitting diodes LED ‘s
✓Solar cells
✓Opto-Electronic diodes

105. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓A photodiode is a P/N diode designed to operate with reverse bias voltage applied to it’s junction
✓some small current ( leakage ) is expected to flow , at room temperature , due to the presence of minority
carriers
✓The level of such current can be increased significantly , if light is allowed to enter the P/njunction area
✓The energy associated with such a light causes the generation of more electron/holes pairs and thus the
large current flow
✓Applications of such devices are on the increase ( e.g. light activated switch , Illumination system
controllers , etc. )
✓Opto-Electronic diodes
✓Photodiodes

106. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓IR diode is a gallium arsenide ( semiconductors materials )
✓gallium arsenide emits light , when forward biased
✓Such a light ( not visible )
✓may be used in communications ( light ) systems e.g. Fiber optics transmitters , Remote controls or
security systems ,
✓Opto-Electronic diodes
✓Infrared ( IR ) Emitters

107. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Light emitting diodes , as the name implies are diodes , gallium / arsenide
✓gallium arsenide emits light , when forward biased
✓The light produced can be several colors , usually Red , Green , Yellow
✓Such diode have many applications such as Display systems , Power indicators
✓Opto-Electronic diodes
✓Light emitting diodes LED ‘s

108. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓Opto-Electronic diodes

109. An-NajahNational University
Faculty of Engineering
Electrical Engineering Department
Electronic Materials and devices
➢Diode circuits and applications
❖Special Diodes
✓A solar cell, or photovoltaic cell, is a semiconductor device consisting of a large-area p-n junction diode,
which, in the presence of sunlight is capable of generating usable electrical energy
✓used as a renewable source of energy
✓Opto-Electronic diodes
✓solar cells