低功耗26万色TFT液晶单芯片驱动器集成电路毕业论文外文翻译Word文档格式.docx

低功耗26万色TFT液晶单芯片驱动器集成电路毕业论文外文翻译Word文档格式.docx

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Abstract

Inthisstudy,wepresenta260k-colorTFTLCDone-chipdrivingICthatconsumesunder5mWinthemodule,whichisexceptionallylowpowerconsumption.Toreducepowerconsumption,weusedmanypower-loweringschemesinthelogicandanalogdesign.AdriverICfordrivingLCDshasabuilt-ingraphicSRAM.Besideswriteandreadoperations,thegraphicSRAMhasascanoperationthatissimilartothereadoperationofonerow-line,whichisdisplayedononelineinanLCDpanel.Currently,theembeddedgraphicmemoryisimplementedbyan8-transistorleafcellanda6-transistorleafcell.Weproposeanefficientscanmethodfora6-transistorembeddedgraphicmemorythatisgreatlyimprovedoverpreviousmethods.TheICisimplementedina0.18umprocess.The0.18ummixedprocessisfirstlyusedinworld.

1.Introduction

Currenttelecommunicationtechnologyhasimprovedamazingly.Theseimprovementshaverevitalizedhand-heldmodulesandincreasedservices.Becauseofthis,itisevenmoreimportantthatthechipenablevoicecommunication,data,graphicimages,andmovingpictures.Touseahand-heldmoduleforalongertime,eachchipneedstobecomesmallerandconsumelesspower.

Improvementsintelecommunicationshavemadedisplaytechnologyimprovetoo.Thesizeofdisplayequipmenthasbecomebiggerandtheresolutionhigher.Duetothis,powerconsumptionofdisplayequipmenthasalsobecomehigher.Powerreductionfordisplayequipmenthasbecomeaveryimportantissue.Thedisplayequipmentinhand-heldphonesissupertwistednematic（STN）andthinfilmtransistor（TFT）LCDs.Electro-luminescencewillbeapracticalutility.Displaymaterialcanhaveanalteredarrangementaccordingtothelevelofvoltageortheamountofcurrent.Inaccordancewiththearrangement,therateofatransmissionchanges.Wecancontrolthebrightnessofadisplaypanel,andtheblack/whitedisplaypanelisimplementedwiththismethod.Themulti-colordisplaypanelisimplementedbyarranginganRGB（red,greenandblue）colorfilter.Thecolorrectangularpanelissuppliedbyrow-directvoltageandcolumn-direct.voltage.Thedifferenceofthetwodirectvoltagesisthedrivingvoltageofthepixels.Thismethodiscalledmultiplexaddressing.TheLCDdriverICgeneratesandsuppliesthevoltagelevel.

Thispaperpresentsa260k-colorTFTLCDone-chipdrivermodulethatconsistsofagatedriverandsourcedriver.Thegatedrivergeneratesthedrivingvoltageofcolumndirectionandcommonvoltage.Figure1showshowtheTFTarrayisconstructed.Thegatedrivingvoltageisoftwotypes:

aselectedlevelandanon-selectedlevel.Thelevelofthesevoltagesisdeterminedbythecharacteristicsofeachpanel.Whenonegatelineisselected,thesourceICdrivesdatavoltagelevelsthatarevaluedbydecodingstoreddata.Thedifferentvoltageofthegate’sselectedlevelandsource’sdataleveldeterminethedisplaymaterialarrangement.

Currently,Withahighercolorresolution,theembeddedmemorycapacityneedstobebiggerintheLCDdriverIC.Withalargermemorycapacity,themetallinefromthelogicparttothememoryneedstobelonger.Becauseofthis,theembeddedgraphicmemory-addressingblock,theembeddedgraphicmemorycontrolblockinthelogic,andatimecontrolblockintheembeddedgraphicmemorybecomesmoreimportantindesigningtheembeddedgraphicmemory.TheinternalcontrolblockintheembeddedgraphicmemoryisespeciallyimportantinACcharacterization.

Thepowerconsumptionofthemergedmemoryalsobecomesaveryimportantissue.Withahigherresolutionandbiggerpanel,abiggerembeddedmemorysizeisnecessary.Becauseofthis,shrinkingtheRAMsizeisadominantfactorinthechipsizeofadriverIC.Becauseofthesefactors,thearchitectureoftheembeddedmemorywasimprovedfroma8-transistorSRAMarchitecturetoa6-transistorSRAMarchitecture.

Inthispaper,sectionIIpresentsthearchitectureofgraphicdrivingIC.SectionIIIdiscussesthearchitectureofthe8-transistor/6-transitorembeddedgraphicSRAMandthearchitecturaldefectofthewrite/read/scanmethodin6-transistorarchitecture.InsectionIV,alowpowerscanmethodin6-transistorarchitectureisproposed.Inthischapter,anotherlowpoweraccessedmethodisproposed.InChapterV,theimplementedsampleiscomparedinpowerconsumption.Thechipsamplesareimplementedina0.18umprocessandtestedinmanualboard.

Figure.1TFTone-chipdriverICdiagram

2.StructureofthedriverIC

Generally,thedriverICiscomposedofalogicpart,ananalogpart,andamemorypart.TheanalogpartiscomposedoftheLCDdriver,DCDCconverter,voltagedivider,andoscillator.Theoscillatorcircuitgeneratesaclockfordisplay.TheDCDCconvertercircuitreceivesthegeneratedclockandgeneratesthehighest/lowestvoltagelevel.Thevoltagedividercircuitdividesbetweenthehighestandlowestlevel.Thedriverblocksuppliesthevariousvoltagestothepanel.Figure1isablockdiagramoftheimplemented260kTFTone-chipIC.The260kTFTone-chipICiscomposedofalogic,amergedmemory,anoscillator,aDCDCconverterblock,asource/gatedriverblockandacommonvoltagegeneratingblock.

ThelogicpartiscomposedofanMPUinterfaceblock,memory-addressingblock,andtimingcontrolblock.TheMPUinterfaceblockinterfacesbetweenthedriverICandtheexternalMPU.Thememory-addressingblockreceivesthedecodedsignalintheMPUinterfaceandgeneratesthememoryaddress.Theesisterarrayisincludedinthegrayscalegenerator.TheimplementeddrivingIChasthreetypesofadjustment:

agradientadjustment,anamplitudeadjustment,andafineadjustment.Thetimingcontrolblockgeneratesasignal,whichcontrolsthedisplaypanel.

Thegatedriverblockdrivesthegateon/offlevelvoltage（VGH/VGOF）.Theeachvoltagegeneratingblocksequencelygenerateseachvoltage.（Fig.2）.TheTFTpanelmusthaveacapacitorforstorage.Thedrivingmethodisatwo-typepercapacitorconnectionthatisnamedthecapacitorforstorageinaTFTpanel（CST）onthegateandtheCSTonthecommon.

Theembeddedmemoryisthesameasnormalmemory.Inaddition,theembeddedmemoryhastheoperationofaccessingwhole-bitcellsintheX-address.Theoutputdatafrommemoryistransferredtothesourcedriver.Thesourcedriverdrivesthepanelwiththevoltagelevel,whichisdecodedbytheaccesseddata.Onetime,thegatedrivercircuitselectsonelineofthepanel.Thenexttime,thegatedrivercircuitselectsthenextline,andtheembeddedmemorytransmitsawhole-bitcellinthenextX-address.Thegatedrivercircuitselectsanext-columnline.Withthisaccessingprocess,onelineoftheLCDpanelisdisplayed.

Figure.2.Sequenceofthevoltagegenerator

Figure.3.Theproposedchipmodule

3.Structureofgraphicmemory

TheembeddedgraphicSRAMiscomposedofabitcellcoreblock,I/O&

pre-chargeblock,acontrolblock,ascanlinedecodingblock,aword-linedecodingblock,ascanlatchblock,andseveralbufferblocks.Thebitcoreblockstoresdisplaydata.TheI/O&

pre-chargeblockcontrolscharginganddischargingofthebit/bitbline.Thescan/wordline-decodingblockcontrolstheword-linecellinthebitcoreblock.Thisblockaccessesstoreddataandstoresdata.Thescan-latchblockdoesscanoperations.

Thecontrolblockreceivesexternalwrite/read/scanenablesignalsfromtheaddress-generatingblockofthelogicpartandregeneratesraminternalsignals.Thereceived-originsignalistransferredthroughalongmetallineandthelengthofthemetallinediffers.Becauseofthis,thewrite-enablesignalofthemostleftword-lineblockcanhaveatimegapwiththemostrightword-lineblock.Theslopeoftheexternalsignalthroughthelongmetallineislowandthedrivengateoftheslopedsignalconsumesmorepower.IftheoriginsignalisusedwithoutrefiningtheI/Oblockandword-lineblock,theoperationofthememoryisunstable.Becauseofthisinstability,asthehigherstoragememoryisembedded,regeneratingthetimingbecomesmoreimportant.

Theregeneratedsignalenablestheaccessoperationwhenthebit/bitblineisperfectlystable.Thecontrolblockhasanauto-detectcircuit,whichdetectsthebit/bitbstabletime.Inthe8-transistorgraphicSRAMarchitecture,theread/writeoperationisthesameasinanormalSRAM.However,aleafcellhastwoadditionaltransistors,whichdirectlyconnecttothestoragepath.Becausetheadditionaltwotransistorsareconnectedtothestoragecellindependentlyofthebit/bitbline,the2-transistorcanindependentlyaccessstoreddata.

Theadditionaltransistorwithadifferentaccesspathmakesitpossibletoaccessstoragedataeventhoughwrite/readisoperating.Becausethe8-transistorhasanindependentscanoperation,thememoryaccesslogicfortheembeddedgraphicSRAMissimple.However,becauseoftheadditional2-transistor,thechipsizeisbiggerthanthe6-transistorgraphicSRAM.InamonoSTNdriverICandalow-resolutionmulti-colorSTNdriver,theembeddedgraphicSRAMsizeisnotdominantinafullchip.Asthepanelbecomesbiggerandtheresolutionbecomeshigher,thesizeoftheembeddedgraphicSRAMbecomesdominantinthedriverIC.Duetothis,currently,the6-transistorembeddedgraphicSRAMisusedin256/65k/260kcolordriverICs.

Figure4.Comparisonof8-trscanand6-trscan.

Ina6-transistorgraphicSRAM,theadditional2-transistorisremoved.Thescanoperationisthesameasinthereadoperation,buttheselectleafcellisawholecolumnlineofonerow.Becausethescanoperationofthe6-transistorgraphicSRAMusesabit/bitbline,whenthewrite