SRAM在Candence中仿真静态噪声容限

DepartmentofElectricalandComputerEngineeringVishalSaxena-1-SRAMStaticCharacterizationVishalSaxena,BoiseStateUniversity([e-mail])VishalSaxena-2-SRAMReadStaticNoiseMargin(SNM)Duringreads,WLandBLareheldatVDDBreakthefeedbackfromthecross-coupledinvertersPlotvoltagetransfercharacteristics(VTC)oftheinverterinthehalfcircuitasshownbelow(V2vsV1)UsethisplottoformthebutterflycurvebyoverlappingtheVTCwithitsinverseRepresentsthetwohalvesdrivingeachotherReadSNMisthesideofthelargestsquarefittedinthebutterflycurveVishalSaxena-3-SRAMReadStaticNoiseMargin(SNM)Sinceit’sdifficultwithSpectretoplottheinverseofthecurveonthesamegraphImporttheV2vsV1inMATLABanddopost-processingtogeneratethebutterflycurveVishalSaxena-4-ReadSNMTestBenchVishalSaxena-5-ReadSNMTestBenchSelectandsavethetraceasa.csvfile,sayVout.csvStartMatlabinthesamedirectoryCanalsouseExcelEitherimportthe.csvfileandplotyourselvesORUsethescriptinthefollowingslidesVishalSaxena-6-MatlabScripttoplotButterflyCurves%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%ScripttoplotSRAMButterflycurve%%SavethevinvsvoutDCsweepplotintheSpectreasa%CSVfile'Vout.csv'%RunthisscriptinthesamedirectoryastheCSVfile%Thefileusesthefunctionimportfile%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%importfile('Vout1.csv');%Changefilenameappropriately%vinisthefirstcolumnvin=data(:,1);%voutisthesecondcolumnvout=data(:,2);figure()plot(vin,vout);holdon;gridon;plot(vout,vin);%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%VishalSaxena-7-MatlabImportfileFunction%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%functionimportfile(fileToRead1)%IMPORTFILE(FILETOREAD1)%Importsdatafromthespecifiedfile%FILETOREAD1:filetoread%ImportthefilenewData1=importdata(fileToRead1);%Createnewvariablesinthebaseworkspacefromthosefields.vars=fieldnames(newData1);fori=1:length(vars)assignin('base',vars{i},newData1.(vars{i}));End%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%VishalSaxena-8-ReadButterflyPlotFitthelargestsquareinthebutterflyTwostablestates(0and1)AhigherSNMindicatesbetterreadstabilityVishalSaxena-9-SRAMWriteNoiseMargin(WNM)Duringawrite,WLisatVDD,andthedataisdrivenontotheBLsBreakthefeedbackfromthecross-coupledinvertersPlotvoltagetransfercharacteristics(VTCs)oftheinverterinthehalfcircuitasshownbelow(V2vsV1andV1vsV2)Here,VTCsofthetwohalvesarenotthesameSinceoneoftheBLisdriventoVDDandotherto0(asymmetry).WriteNMisthesideofthelargestsquarefittedinbetweenthetwocurvesVishalSaxena-10-WriteNMTestBenchVishalSaxena-11-WriteButterflyPlotFitthelargestsquarebetweenthecurvesTwostablestates(0and1)AhigherWNMindicatesbetterwritestability