基于单片机的数字时钟设计--外文翻译

Abstract Virtually complete charge transfer can be achieved with charge coupleddevices(CCDs)intheburiedchannelconfigurationbecausetheburiedchannelCCDintroduces no transfer noise. However, conventional charge detectors incorporatedinto CCDs have a comparably large noise, which consists of thermal noise and 1/fnoisefromMOS transistorin theoutputchargedetectors.

Chapter10

Low-NoiseElectronicImaging

withDouble-GateFETs

andCharge-ModulationDevices

YoshiyukiMatsunaga

AbstractVirtuallycompletechargetransfercanbeachievedwithchargecoupleddevices(CCDs)intheburiedchannelcon gurationbecausetheburiedchannelCCDintroducesnotransfernoise.However,conventionalchargedetectorsincorporatedintoCCDshaveacomparablylargenoise,whichconsistsofthermalnoiseand1/fnoisefromMOStransistorintheoutputchargedetectors.

HighlysensitivedoublegatechargedetectorsarepresentedinthischaptertoshowtheabilityofCCDlownoiseperformanceoflessthan1electronrmsatroomtemperatureandatvideofrequency.

Theconceptofdoublegatechargedetectioncanalternativelybeimplementedinapixelincorporatingachargemodulationdevice(CMD),reachingalsoaneffectivereadoutnoiseleveloflessthan1electronrms.Inpractice,theCMDshowslarger xed-patternnoisebehavior,necessitatingsupplementarysignalprocessingefforts.10.1Introduction

Chargecoupleddevices(CCDs)haveachievedvirtuallycompletechargetransferbyusingtheburied-channelcon guration,resultinginchargetransferinef cienciesoflessthan10 6.Also,theburied-channelCCDoperationintroducesnotransfernoise.However,conventionalchargedetectioncircuitsemployedinCCDshaveacomparativelylargenoise,whichconsistsofthermalnoiseand1=fnoisefrommetaloxidesemiconductor(MOS)transistorsinthechargedetectors[1].ThedetectornoisesourcesdegradetheCCDperformancesigni cantly.

Inthischapter,highlysensitivedouble-gatechargedetectordevicesarepresentedtoexploittheabilityofCCDlownoiseperformancewhichisoneofthemostimpor-tantcharacteristicsforimagesensorapplications.LowleakagecurrentCCDsensorswithalow-noisechargedetectorwillideallybealmostnoiselessphotosensorsInaddition,anewcharge-modulationimagepixelispresentedforapplicationsofthedouble-gatedetectors.

P.SeitzandA.J.P.Theuwissen(eds.),Single-PhotonImaging,

SpringerSeriesinOpticalSciences160,DOI10.1007/978-3-642-18443-7©Springer-VerlagBerlinHeidelberg2011219

Abstract Virtually complete charge transfer can be achieved with charge coupleddevices(CCDs)intheburiedchannelconfigurationbecausetheburiedchannelCCDintroduces no transfer noise. However, conventional charge detectors incorporatedinto CCDs have a comparably large noise, which consists of thermal noise and 1/fnoisefromMOS transistorin theoutputchargedetectors.

220Y.Matsunaga10.2Double-GateFETChargeDetector

Theprimaryparameterdominatingthenoiseperformanceofachargedetectoristheeffectivecapacitanceatthegateofthe rsttransistor,asexplainedforexampleinthe rstchapterofthisbook.Forthisreason,asuccessfulstrategyfortherealizationofultra-low-noisephotosensorsisthedesignofchargedetectorswithverylowsensingcapacitance,preferentiallybelow1fF.Thedouble-gateFETstructureisveryusefulforthispurposebecauseofbothitshighsensitivityduetolowsensingcapacitanceanditslownoiseduetocompletechargetransferinthechargedetector.Thedouble-gateFETcanbeimplementedeitherasa oatingwellorasa oatingsurfacedevice.10.2.1FloatingWellType

Anewhigh-sensitivityCCDoutputampli ercalled“double-gate oatingwelldetector”hasbeenfabricatedandevaluated.Atroomtemperature,thenewdetectorachievesacharge/voltageconversiongainof76 V/electronandanoiseequivalentsignalof1.2electronsrmsovera3.58MHzvideobandwidth.

Thisdetectorconsistsofann-typeburiedsensingchannelandaP-typebulkchanneldetectiontransistorcrossingunderneaththesensingchannel,representingthedoublegateFET.ThisstructureisveryusefulforaCCDimagesensorwhichhandlesasmallsignalchargeofafewthousandphotogeneratedelectronsorholes.10.2.1.1DeviceStructure

AlmostallchargedetectorsforCCDimagesensorsare oatingdiffusiondetectors.Figure10.1showsthetopviewofthedetectorincorporatedintotheendofaCCDregister.SignalchargesareclockedalongtheCCDregisterandtransferredoutintoaCCDsensingchannel.Sensingchannelpotentialismodulatedbysignalcharges,andamodulatedpotentialissensedbythedetectionMOStransistor’sgate.Theoutputvoltagesignalsarebufferedbydoublestagesourcefollowers.Thedetectionsensitivityisdeterminedbytheconversiongainforsignalchargestotheoutputvoltages,thatis,bytheeffectivesensingcapacitance.

However,thesensingcapacitanceoftheconventionaldetectorcannotbesuf -cientlysmallforthefollowingreasons:First,thesensingchannelhasacompar-ativelylargeareabecauseitinevitablyhasacontacthole.Second,thedetectiontransistorgatecapacitancemustbeaddedtothesensingcapacitance.Third,thedetectorsuffersfromlargekTCnoise,correspondingtocharge uctuationintheresetgateOFFperiodduetoresetgatechannelthermalnoiseintheONperiod.ThenewlydevelopedchargedetectorhaslowsensingcapacitanceandastructurethatisfreefromkTCnoise.Theprincipleisacombinationofann-typeburiedsensingchannelandaP-channeldetectiontransistoracrossit,asshowninFig.10.2

Abstract Virtually complete charge transfer can be achieved with charge coupleddevices(CCDs)intheburiedchannelconfigurationbecausetheburiedchannelCCDintroduces no transfer noise. However, conventional charge detectors incorporatedinto CCDs have a comparably large noise, which consists of thermal noise and 1/fnoisefromMOS transistorin theoutputchargedetectors.

10Low-NoiseElectronicImagingwithDouble-GateFETs

Fig.10.1Planeviewof

conventional oating

diffusioncharge

detector221

Fig.10.2Plainviewofnew

oatingwell

detector

[2,3].Figure10.3showsacross-sectionalviewofthedetectiontransistoracrossthesensingchannel.Ashallowp-wellwithasensingchannelinitandsource/drainpCregionsareformedonann-typesubstrate.TheholecurrentintheP-channeldetectiontransistorismadeto ownotalongthesilicon–silicondioxideinterfacebutratheru …… 此处隐藏：6021字，全部文档内容请下载后查看。喜欢就下载吧 ……