Programmable voltage reference generator for a SAR-ADC

83 Pages·2013·0.79 MB·English

Institutionen för systemteknik
Department of Electrical Engineering
Examensarbete
Programmable voltage reference generator for a
SAR-ADC
ExamensarbeteutförtiElectronicsSystems
vidTekniskahögskolanvidLinköpingsuniversitet
av
GeorgiosMylonas
LiTH-ISY-EX–13/4717–SE
Linköping2013
DepartmentofElectricalEngineering Linköpingstekniskahögskola
Linköpingsuniversitet Linköpingsuniversitet
SE-58183Linköping,Sweden 58183Linköping

Programmable voltage reference generator for a
SAR-ADC
Examensarbete utfört i Electronics Systems
vid Tekniska högskolan vid Linköpings universitet
av
GeorgiosMylonas
LiTH-ISY-EX–13/4717–SE
Handledare: JJacobWikner
Examinator: JJacobWikner
Linköping,11september2013

Avdelning,Institution Datum
Division,Department Date
ElectronicsSystems
DepartmentofElectricalEngineering 2013-09-11
SE-58183Linköping
Språk Rapporttyp ISBN
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(cid:3)Svenska/Swedish (cid:3)Licentiatavhandling ISRN
(cid:3)(cid:2)Engelska/English (cid:3)(cid:2)Examensarbete LiTH-ISY-EX–13/4717–SE
(cid:3)C-uppsats
Serietitelochserienummer ISSN
(cid:3)D-uppsats Titleofseries,numbering
—
(cid:3) (cid:3)Övrigrapport
(cid:3)
URLförelektroniskversion
http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-XXXXX
Titel ProgrammablevoltagereferencegeneratorforaSAR-ADC
Title ProgrammablevoltagereferencegeneratorforaSAR-ADC
Författare GeorgiosMylonas
Author
Sammanfattning
Abstract
SAR-ADCsareverypopularandsuitableforconversionsuptofewtensofMHzwith8to12
bitsofresolution.AverypopulartypeistheChargeRedistributionSAR-ADCwhichisbased
onacapacitivearray. Higherspeedscanbeachievedbyusingtheinterleavingtechnique
whereanumberofSAR-ADCsareworkinginparallel. Thesespeeds,however,canonlybe
achievedifthereferencevoltagecancopewiththeswitchingofthecapacitivearray.
InthisthesisthedesignofaprogrammablevoltagereferencegeneratorforaChargeRedis-
tributionSAR-ADCwasstudied.Anumberofarchitectureswerestudiedandonebasedona
CurrentSteeringDACwaschosenbecauseofthesettlingtimethatcouldoffertotheCharge
RedistributionSAR-ADCswitchingoperation.Thisarchitecturewasfurtherinvestigatedin
ordertospottheweakpointsofthedesignandtrytominimizethesettlingtime.
Intheend,thefinaldesignwasevaluatedandpossibletrimmingtechniqueswereproposed
thatcouldfurtherspeedupthedesign.
Nyckelord
Keywords voltagereference,ADC,DAC

Abstract
SAR-ADCsareverypopularandsuitableforconversionsuptofewtensofMHz
with8to12bitsofresolution. AverypopulartypeistheChargeRedistribution
SAR-ADC which is based on a capacitive array. Higher speeds can be achieved
by using the interleaving technique where a number of SAR-ADCs are working
inparallel. Thesespeeds,however,canonlybeachievedifthereferencevoltage
cancopewiththeswitchingofthecapacitivearray.
In this thesis the design of a programmable voltage reference generator for a
Charge Redistribution SAR-ADC was studied. A number of architectures were
studied and one based on a Current Steering DAC was chosen because of the
settling time that could offer to the Charge Redistribution SAR-ADC switching
operation. This architecture was further investigated in order to spot the weak
pointsofthedesignandtrytominimizethesettlingtime.
Intheend,thefinaldesignwasevaluatedandpossibletrimmingtechniqueswere
proposedthatcouldfurtherspeedupthedesign.
iii

Acknowledgments
First of all, I would like express my special thanks of gratitude to Dr. Jacob
Wikner for his support and guidance throughout this project. His comments
andhishelpwereeducatingandinspiring.
IwouldalsoliketothankDr. RobertHägglundfromAnaCatumABwhotrusted
mewiththisprojectandMr. PavelAngelovforhishelpandsuggestions.
IwouldliketothankmyfiancéeCharaforhersupportandherpatienceduring
mystudies.
Finally,Iwouldliketothankmyparentsandmysisterfortheirsupportandtheir
unconditionallove.
Linköping,September2013
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