1. Potentialenergyofanorbitingelectron isalwaysnegative.Itcanneverbepositive.

2. Valancebandinasolidcannotbeempty.3. Conductionbandlieabovethevalanceband.4. The neighboring atoms in a crystalline latticestructureofasemiconductorlikeGeformcovalentbond.

5. Intrinsic semiconductors are those which aremadeofthematerialinitspurestform.

6. For converting intrinsic semiconductor into Ntypeextrinsic,apentavalentimpurityisaddedlikePhosphorous, Arsenic, Antimony (Sb), andBismuth. While for Ptype extrinsic a trivalentimpuritylikeB,Al,Ga,andIndiumetc.isadded.

7. In Ntype electron are majority & holes areminority carriers while vice versa in Ptypesemiconductors.

8. Number of electrons and holes are same inintrinsic semiconductor but bot in extrinsicsemiconductor.

9. Both in Ntype and Ptype semiconductormaterialasawholeiselectricallyneutral.

10. Extrinsicsemiconductorsarewidelyusedbecauseit shows wide ranging characteristics dependinguponnatureandamountofimpurity.

11. Three most commonly used semiconductormaterial are Ge, Si, GaAs. Transferredelectronbulkeffectoccursingalliumarsenide.

12. GaAshashighestforbiddenenergygap. InGe itsvalueis0.67ev.

13. Theprocessofaddingimpuritytosemiconductorinacontrolledamountiscalleddoping.

14. NN junction and PP junction are regionsbetweentworegionshavingdifferentpropertiesinNtype & PType semiconductor materialrespectively.

15. In forward biased condition the potential of PsidewithrespecttoNsideispositive.

16. In semiconductor diode relation of current isexponentialwithvoltage.

17. CutinvoltageinsiliconandGEis0.6&0.218. Themaximum voltage a diode canwithstand inreversebiasediscalledpeakinversevoltage.

19. TheDC&ACopposition to thecurrent flow inadiode is called static & dynamic resistancerespectively.

20. When emitter junction is forward biased &collector junction is reverse biased thensemiconductortransistoroperatesinactiveregion.

21. A zenor diode which generally operates inreversebiasedmode isusedtomaintainconstantoutputvoltageinapowersupply.

22. Theimportantspecificationsofazenordiodeare:breakdown voltage, dynamic impedance andpowerdissipation.

23. When current through zenor diode increase bysomefactor,thevoltageremainsunaltered.

24. The dynamic impedance of a zenor diodedecreasewithincreaseincurrentthroughit.

25. When zenor diode are connected in series thevoltagesimplyadd.

26. The breakdown that occur in reverse biasedcondition innarrow junctiondiode iscalledzenorbreakdown while in wider junction diode, it iscalledavalanchebreakdown.

27. Variationinbreakdownvoltagewithtemperatureis called temperature coefficient of a breakdowndiode. It is positive in zenor while negative inavalanchediode.

28. Symbol.Representsazenordiode.29. Some common name of diodes are: varactor,Gunn, Tunnel, RIMPATT, IMPATT, backwardm ,Schottkybarrier,LSA,CrystelandPINdiode.

30. TRAPATThashigherefficiencythanIMPATT.31. Diode used at microwave frequencies areschottky, barrier, crystal and backwardwhile PINdiodeisnotused.

32. Thediodenotsuitable for lowpowerosscilationareGunn, IMPATTand LSAwhile Tunneldiode issuitable.

33. The diode which donot produce highest pulsepower are varacor, Gunn and schottky barrierwhileRIMPATTproduces.

34. Performancesof the followingdiodes arebasedon their negative resistance characteristic:Gunn,IMPATTandTunnelwhile inbackwarddiode it isnotbasedonthis.

35. Like zenor avalanche diode also operate inreverse biased mode so current is because ofminoritycarriers.

36. Twodiodeshavingrating6.2V&24Varezenorand avalanche diodes (variation in voltagepossible).

37. The electrons present in outermost orbit arecalledvalanceelectrons.

38. The number of proton in an atom is called itsatomicnumber.

39. Electrons and holes are equal in germanium.Adding small amount of antimony will producemoreelectrons.

40. An ordinary PN junction diode with higherimpurityconcentration inPandNregion iscalledtunneldiode,sodepletionwidthdecreases. Ithasa neagative resistance region and it fabricateeitherfromGEorGaAs.

41. Anexampleofpassivecomponentiscapacitor.42. Intrinsic type, extrinsic type, Ptype & Ntypesemiconductors are electrically uncharged orneutral.

43. In PN junction, the region containinguncompensatedacceptoranddonor ions iscalleddepletionregion.

44. APNjunctiononlyconductsinforwarddirection.45. In reverse biased PN junction, the currentthrough the junction increases abruptly atbreakdownvoltage.

46. TheVIplotofsiliconandGEis:

47. PlotbetweenVIforidealdiodeis:48. Maximumrectificationefficiencyforhalfwave&fullwaverectifieris40.6%&81.2%.

49. FigureforLED&Tunneldiodeare:50. Barrier potential decreases in forward biased&increasesinreversebiasedcondition.

51. All valance electrons tend to remain in valanceband as the temperature of semiconductor isreducedtoabsolutezero.

52. Theenergygap isoftheorderof515ev incaseofinsulators.

53. Barrierpotentialforsilicondiodeis0.7V.Itis0.3VforGE.

54. Holesandelectronsmoveaway from junction inreversebiasedcondition.

55. Whenanorbitingelectroniscompletelyremovedfromanatom,itissaidtobeionized.

56. Silicon is Z=14, its outer shell is half filled andelectronicdistributionis2,8,4.

57. Maximum number of electron in valance shellandMshellare8and18respectively.

58. Semiconductormaterialshavecovalentbonds.59. Majorpartofcurrentinintrinsicsemiconductorisduetoconductionbandelectrons.Theconductionband electrons have more mobility than holesbecausetheyneedlessenergytomove.

60. Doping materials alter the crystal structures ofthepuresemiconductor,socalledimpurity.

61. Currentflow inasemiconductordependsonthephenomenonofdrift,diffusionandrecombination.

62. The process of adding impurity to puresemiconductorsiscalleddoping.

63. Most widely used semiconducting material inelectronicdevicesissilicon.

64. Electronhole pairs are produced by thermalenergy.

65. When an electron falls into a hole thenrecombinationtakesplace.

66. When a PN junction is formed, then barrierpotentialisformedbecauseofdiffusioncurrent.

67. The leakagecurrentofaPNdiode iscausedbyheatenergy.

68. Electronic components which are made of asemiconductormaterialareoftencalledsolidstatedevices.

69. Any voltage that is connected across a PNjunction is calledbias voltage. It isDC voltage tocontroloperation.

70. Theareawithinasemiconductordiodewherenomobilecurrentcarrierexist(becausetheymigrate)iscalleddepletionregion.

71. In forwardbiased an external voltage is appliedwhichispositiveatanodeorPregionandnegativeat cathode orNregion. So it conduct current. Insilicon itshouldbemore than0.7V. Itappear likeONswitch.

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81. InforwardbiasedresistanceisoftheorderofwhileitisoftheorderofM in reverse biased.

82. In reverse biased P-N junction, there is almost no current.

83. A P-N junction acts like unidirectional switch.84. Leakage current across a P-N junction is due to

minority carriers (of the order of A).85. In extrinsic semiconductor the effect of

temperature rise is pronounced on minority carriers. After critical temperature ( Si= and GE = it becomes intrinsic semiconductor because broken hole-electron become equal.

86. At room temperature an intrinsic silicon crystal acts like an insulator.

87. Base region in N-P-N transistor is of boron..1. Field Effect Transistors (FETs) are smaller

than BJTs. Manufacturing process is simple. MOS technology is used so they are called MOSFET.

2. InNchannelMOSFETPtypesubstrateisused.It has two Ntype regions which are heavily

doped,one iscalledsource,other iscalleddrainregion. voltage isappliedbetweendrainandsource.

3. Path between drain and source has highresistanceofthevalueof .

4. In MOSFET three different operating states are cutoff, triode, and saturation.

5. MOSFET would be in cutoff state if voltage applied on gate is less than threshold voltage.

6. Threshold voltage is controlled during fabrication process (0.5-1.0 V).

7. On gate an insulator used to cover Ptypesubstrate is . Then metal is deposited onoxidelayertoformgateelectrodeofthedevice.

8. Ptypesubstratebetweendrainandsource iscalledbodyofFET.

9. When voltage above threshold is applied atgate terminal then carrier depletion channel isformed between drain and source. If voltage is

applied between drain and source then currentflowthroughinducedNregion(nchannel).

10. TheFEToperatesonmajoritycarrieronly.11. MOSFET operates both in depletion andenhancementmodes.

12. An Nchannel depletion mode MOSFET isnormally ON device requiring negative gatevoltagetoturnitOFF.

13. In FET common source has high input &outputresistance.

14. In FET common gate has low input & highoutputresistance.

15. In FET common drain has high input & lowoutputresistance.

16. Input resistance of FET is not lower ascomparedtobipolar.

17. Grounding rings are used with MOSFETs inorder toavoidany strayor static voltageof thegatewhichmaydestroy layer.

18. The input gate current of a FET is negligiblysmall.

19. FET has very high input impedance but notmorethanCCBJT.

20. For enhancement only Nchannel MOSFET,polarityof ispositive.

21. ThebestelectronicdeviceforfastswitchingisMOSFET.

22. FETs have similar proportions to NPNtransistors.

23. AMOSFETusestheelectricfieldofacapacitortocontrolthechannelcurrent.

24. In FET, there are two PN junctions at thesides.

25. Thermal runaway is not possible in FETbecauseas the temperatureofFET increase, themobilitydecreases.

26. The threshold voltage of an nchannelMOSFETcanbeincreasebyreducingthechannellength.

27. The MOSFET switch in its onstate may beconsiderequivalenttocapacitor.

28. A switchedmode power supply operating at30 kHz to 100 kHz range uses MOSFET as themainswitchingelement.

29. ThechargecarriersinpchannelFETareholesonly,whileinnchannelelectronsonly.

30. MOSFETisaffectedbystaticelectricity.31. Four diode bridge has lower peak inverserequirement as compare to full wave rectifierusingtwodiodes.

32. FET depends on the variation of the reversevoltageforitsoperation.

1. Zenor diode has characteristics close to anidealvoltagesourcewhile transistor inCBmodeisclosetoidealcurrentsource.

2. Gallium phosphide finds applications in lightemittingdiodewhileGalliumarsenideisusedforinfraredLEDs.

3. LEDs normallywork on voltage of 12Vwithpowerconsumptionof510mA.Itdonotrequireheatingorwarmuptime.

4. A tunnel diode is used for microwavefrequencies. Varactor uses two junction ofoppositepolarity.

5. If isno loadvoltage& is loadvoltagethenregulationis:( )100.

6. Ifno loadvoltage is52Vand full loadvoltage is50Vthen%agevoltageregulationis4%.

7. Excessivehum inpower supply couldbedue tocapacitor.

8. The ideal characteristics of a stabilizer areconstant output voltage and low internalresistance.

9. Silicondiodeislesssuitedforlowvoltagerectifieroperationbecauseitsbreakdownvoltageishigh.

10. As compared to full wave rectifier using twodiode, the four diode bridge rectifier has the

dominantadvantageoflowerpeakinversevoltagerequirement.

11. Silicon diode are used in rectifier circuit moreabundantly because they can withstand highertemperaturethanGE,CostmuchlessthanGE,andturnoffisnearlydoublethanGE.

12. Acrystaldiodeisusedasrectifier.13. InLEDlightisemittedbecauserecombinationofchargetakesplace.

14. SCRisanactivedevice.15. Insemiconductordiodebarrieroffersoppositiontomajoritycarriersinbothregions.

16. The current in reverse bias, in a PN junctiondiodemaybefewmicroorNanoamperes.

17. TheefficiencyofFullwaveisdoubleofHalfwaverectifierbecauseitutilizesbothhalfcycleofinput.

18. Theoutputofhalfwave rectifier is suitableonlyforrunningACmotors.

19. The primary function of a rectifier filter is toremoveripplesfromtherectifiedoutput.

20. InLCfilter,theripplefactorremainconstantwiththeloadcurrent.

21. InDCpowersupplyableeder resistor isused toimproveregulationandfilteringaction.

22. RegulatorofDCpowersupplyuseZenorasmaincomponent.

23. IfinbridgerectifierACsourceisconnectedtoDCterminals,thenallourdiodeswillburnout.

24. Inan inverting type switching regulators,outputvoltageisoppositetoinputvoltage.

25. A crystal diode has one PN junction and itsforwardresistanceisoftheorderof.Itisusedasa rectifier in forward biased. Its DC resistance isless thanAC resistance. Its leakagecurrent,whichis due to minority carriers, will increase withtemperature.Itisanonlineardevice.

26. If doping level is increased then width ofdepletionregionincreases.

27. Zenor diode has one PN junction but dopinglevelinZenorismorethancrystaldiode.

28. In the breakdown region Zenor behave like aconstantvoltagesource.

29. AZenordiodeisdestroyedifitcarriesmorethanratedcurrent,soaseriesresistanceisconnectedtoprotecttheZenor.

30. Zenor diode which is a nonlinear device hassharpbreakdownvoltage.

31. Solidstate rectifier has the lowest forwardresistance.

32. MainAC power is converted intoDC power forusinginelectronicequipment.

33. Outputofhalfwaverectifierisdifficulttofilter.34. A 10V power supply would use electrolyticcapacitor as filterwhile 1000V supplywould usepapercapacitorasfiltercapacitor.

35. The choke input filter circuit results in the bestvoltageregulation.

36. Most widely used rectifier is fullwave bridgerectifier.

37. Aphotodiodeisnormallyreversebiased.

38. Varactor which is usually reverse biased isassociatedwithvoltagecontrolledcapacitor.

39. Todisplay0in7segmentdisplayonlygsegmentshouldbeoff.

40. In an unregulated power supply if input ACvoltageincreases,theoutputvoltagedecreases.

41. Ifvoltageregulationis10%thenitisunregulatedpowersupply.

42. Zenor diode can be used for both AC & DCvoltageregulators(inshunt).

43. Increasing junction temperature, voltagebreakdownpointforZenorandavalanchedecreaseandincreaserespectively.

44. Zenordiode,whicharegenerallymadeofsilicon,hasothernamecalledbreakdowndiode.

45. For increasingvoltageratingtheZenordiodeareconnectedinseries.

46. In Zenor voltage regulator, the change in loadcurrentproducechangesinZenorcurrent.

47. A Zenor voltage regulator is used for very highload current. It will cease to act as a voltageregulatorifZenorcurrentbecomeszero.

48. If doping level is increased, the breakdownvoltageoftheZenorisdecreased.

49. A30VZenorwillhavedepletionlayerwidthmorethanthatof10VZenor.

50. Thecurrent inZenordiode is limitedbyexternalresistance&powerdissipation.

51. When load current is zero, the Zenor current ismaximumandviceversa.

52. AnSCRhasfourlayersandthreePNjunctions.Ithas three terminals: (i) Cathode, (ii) Anode, (iii)Gate. It behaves as unidirectional switch. It issometimescalledthyristor.Thecontrolelement isGate which is positive w.r.t. cathode in normaloperation. Itcombinesthe featureofrectifierandtransistor.

53. AnSCRisacurrenttriggereddevice,sototurnoninnormalwayappropriategatecurrent isapplied.

Toturnoffanodecurrent isreducedtozero.Onlysmallleakagecurrentflowinoffcondition.

54. WecancontrolACpowerinaloadbyconnectingtwoSCRsinparallelcombination.

55. When SCR starts conducting, then gate loses allcontrol.

1. Incaseof forwardbiasedPNPtransistor:base&collector are negative w.r.t. emitter, collector ismorenegativew.r.t.base.

2. In case of forward biased NPN transistor:collector & base are positive w.r.t. Emitter,Collectorismorepositivew.r.t.Base.

3. In bipolar transistor (PNP & NPN) emitter isheavily doped and have low resistivity, base islightlydopedandhavehighresistivityandcollectorhashighresistivitythanemitter.

4. Current amplification factor and commonemitter forwardamplification factor are / &/ where=/(+1).

5. A small change in base current produce a largechange in collector current so is high ascomparedto.

6. Innormaloperationoftransistorcollectorbaseisreverse biased while emitterbase is forwardbiased.Somostoftheelectronsofemitterpasstocollector.

7. A PNP transistor has two Pregions and oneNregion.ItisviceversainNPN.

8. CEtransistorhashighvoltage&currentgainandoutput is phase shift w.r.t. input. Its inputimpedanceishigh.

9. When CE transistor is in cutoff then maximumvoltage appear across the collector and when= / ,thenitissaidtobeinsaturation.

10. When thentransistorisinactiveregion.11. When =0thentransistorisinsaturationmode.12. When = thentransistorisincutoffstate.Inthiscase =0& =0.

13. Biasingof transistor isnecessary to fix thevalueofcurrentamplification.

14. Maximum current pass through emitter somaximum power is dissipated in emitter that iswhyitisdopedheavily.

15. = is the approximation often used inelectroniccircuits.

16. WhenatransistorisfullyswitchedONitissaidtobesaturated.

17. Ifachange inbasecurrentdoesnotchange thecollectorcurrent,thetransistoramplifier issaidtobesaturated.

18. InBJTthelargestcurrentflowoccurinemitter.19. In properly connected BJT, an increase in basecurrentcauseincreaseinboth & .

20. EarlyeffectinBJTreferstobasenarrowing.21. The positive swing of the output signal in atransistor start clipping firstwhenQpoint of thecircuitmoves towards the cutoffpoint(Negativeswingforsaturationpoint).

22. IncaseofBJTamplifier,biasstability isachievedbykeepingthebasecurrentconstant.

23. Improper biasing of a transistor circuit leads todistortioninoutputsignal.

24. WhenBJTisemployedasanamplifier,itoperatesintheactiveregion.

25. Voltagedividerbiasisindependentof.26. Anidealamplifieristheonewhichrespondsonlytosignalsatitsinputterminal.

27. Thenumberofdepletion layers ina transistor istwo.

28. Collectorhas thebiggest size andbase is lightlydoped.Collectorismoderatelydoped.

29. Atransistorisacurrentoperateddevice.30. In an NPN transistor holes are the minoritycarriers.

31. Valueofinatransistorislessthanone.32. Inputimpedanceoftransistorislow& = + 33. Output impedance of transistor is high &generally20

34. InputimpedanceishighinCC,outputimpedanceis high in CB while most commonly usedarrangementisCE.

35. Phasedifferencebetween input&output inCC,CEandCBarezero,180degreeandzero.

36. VoltagegaininCC&CEislessthanone&highestrespectively.

37. Power gain of a transistor is highest in CEarrangement.

38. Arrow inthesymbolofatransistor indicatesthedirectionofholescurrentintheemitter.

39. TheleakagecurrentinCEismorethanthatinCBarrangement.

40. Aheatsink isgenerallyusedwitha transistor topreventexcessivetemperaturerise.

41. Transistor biasing represents DC conditions sobiasingisdonetokeepproperdirectcurrent.

42. If biasing is not done, it results in unfaithfulamplification.

43. Forfaithfulamplification,thevalueof shouldnotfallbelow0.7Vforsilicontransistor.

44. For proper operation collector should haveproper reverse bias and for faithful amplification shouldnotfallbelow1Vforsilicontransistor.

45. The point of intersection ofDC&AC load linesrepresentsoperatingpoint,alsocalledQpoint.

46. The disadvantage of base resistor method oftransistorbiasingisthat,itissensitivetochangein.

47. Theoperatingpointisalsocalledquiescentpoint.ItshouldbelocatedatmiddleofDCloadline.

48. Thedisadvantageofvoltagedividerbiasisthat,ithasmanyresistors.

49. Thepurposeofresistanceintheemittercircuitofa transistor amplifier is to limit the change inemittercurrent.

50. Intransistoramplifiercircuit = + .51. For faithful amplification should not fallbelow0.7VinGEtransistor.

52. Inbase resistormethod if changesby50 thencollectorcurrentalsochangesbyafactorof50too.

53. In the design of a biasing circuit, the value ofcollector load is determined by consideration.

54. If temperature increase then value of decrease.

55. isalmostindependentof .56. Since collectorbase is reverse biased, so itcollects electrons from base in case of NPN andholes from base in case of PNP transistor(minority).

57. In NPN transistor, the function of emitter is toemitorinjectelectronintothebase.

58. TheFET isunipolarwhile junctiontransistorsarebipolar.

59. Fortransistoraction,itisnecessarythatthebaseregionmustbeverynarrow.

60. Aquiescentstateofatransistor impliesthatthetransistorpindenotescollector.

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