诺丁汉电气电子工程部2 eldh62eld-example sheet 3H62ELD2011示例表.pdfVIP

UniversityofNottingham

DepartmentofElectricalandElectronicEngineering

ElectronicEngineering(H62ELD)

ExampleSheet3–DataConverters

(AllthediagramsforQuestions7aretakenfromElectronicDevices–

ConventionalCurrentVersion–SeventhEdition

byTLFloydPearson/PrenticeHall(2005)ISBN0-13-127827-4)

ReadthenotestoofSection4.2

1NoiseinaparticularAnaloguetoDigitalConverter(ADC)has

aumvalueofaround10V.Itisrequiredthatthe

resolutionoftheADCisequaltothisnoisevoltage.

Determinethesupplyvoltage(i.e.umanalogue

voltage)requiredtoproduce:

i)a16bitADC[0.66V]

ii)a20bitADC[10.5V]

iii)a30bitADC[10.737kV]

Commentonyourresults.(Hint:Whatanaloguevoltage

correspondstoall1’sinthebinaryword:111…111ineach

case-thisisthesupplyvoltagerequired)

ReadthenotestoofSection4.3.1

2Considera10-bitDualSlopeADCwithaclockfrequencyof60

kHz.Determinethelongesttimeforaconversion.[34.2ms]

3DualSlopeADC’shavetheadvantagethattheydonotrequire

a“SampleandHold”circuit,thatistheycanprocessasinput

acontinuallyvaryinganaloguesignal.Thiscanbe

advantageousinfilteringoffmainsinterferenceof50Hz.

i)Whatshouldheintegrationtimesothatthemains

componentoftheinputsignalisaveragedout?[0.02s]

ii)Supposingyouwishtomakea16-bitdualslopeADC

thatconvertstheinputsignalandaveragesoutmains.

Determinethefastestclockfrequencyth