Noise-Analysis

DepartmentofElectricalandComputerEngineering©VishalSaxena-1-SpectreNoiseAnalysisVishalSaxena,BoiseStateUniversity([e-mail])©VishalSaxena-2-MakingResistorsNoiselessUseAnalogLib→rescomponentSet“Generatenoise”parametertoNo©VishalSaxena-3-.noiseAnalysis©VishalSaxena-4-PlottingResults©VishalSaxena-5-DirectPlotFormCanchangeunitstoPSDorVSDAddplotstooutputs©VishalSaxena-6-PlottingResultsNotethatthismodeldidn’thaveflickernoiseVN2()isoutputnoise.CanplotinputnoiseandchangetheunitsUnderstandthefrequencyresponseeffectswhenplottinginputnoiseandseeiftheplotmakessense!©VishalSaxena-7-NoiseSummaryReports©VishalSaxena-8-NoiseSummaryReports©VishalSaxena-9-IntegratedNoiseSummaryUsethefiltersappropriatelyforthenoisereports©VishalSaxena-10-TransientNoiseSimulationCreateanewtransientsimulation,openthetransientoptionsform,thenaddthetransientnoiseparameterstotheAdditionalOptionsfield.noiseseed=1,noisefmax=10G,noisescale=1©VishalSaxena-11-TransientNoiseSimulationUseFFTtointerpretnoisespectrum©VishalSaxena-12-SampledCircuitNoiseAnalysisUse.pnoisealongwith.pssanalysisLookattheSpectrePSSsetupslidesPNOISEanalysisworkssimilartothe.noiseanalysisforCTcircuitsSameplottingandnoisereportformsasshownfor.noiseanalysis©VishalSaxena-13-SimulationSetup---PSSWecanonlysetthenumberofharmonicsto0bychoosingShootingmethodtstabparametercanbeobtainedbytrananalysisfirst©VishalSaxena-14-PSSAccuracySuggestionsGotoSimulationOptionsAnalogMainintheADEwindowtosetuptoleranceoptionsaccordingly.IfthefrequencyofperiodicsmallsignalanalysesfollowedbyPSSishigh(e.g.1G),themaxacfreqparameter(optionsaccuracy)ofthePSScanbeusedtospecifythehighestfrequency,otherwise,thefrequencyanalysisinPACmaybetruncated.©VishalSaxena-15-PNOISEAnalysisSimulationofnoiseinsampledcircuitsExample:Switch-CcircuitHereanNMOSswitchwithC=1pF,fclk=10MHzSetupPSSanalysisforthefclk=10MHzclock15©VishalSaxena-16-PNOISEAnalysis16Includesufficientnumberofmaxsidebandforaccuracy©VishalSaxena-17-PNOISEAnalysis17Simulationshows89μVofoutputRMSnoiseIdeal√(kT/C)value=64μV,Simulationresultsclosetotheapproximationof√(kT/C)©VishalSaxena-18-PNOISEAnalysis18AccuracyistightenedbyusinglargenumberofmaxsidebandparameterDetermineshowmanysidebandaliasintothegivenbandTrades-offsimulationtimewithaccuracyForanalyticaldetails,referto:©VishalSaxena-19-References1.SpectreUserSimulationGuide2.K.Kundert,“SimulatingSwitched-CapacitorFilterswithSpectreRF,”TheDesigner’sGuideCommunity,://“AnIntroductiontoCyclostationaryNoise,”TheDesigner’sGuideCommunity,“DeviceNoiseSimulationofDelta-SigmaModulators,”TheDesigner’sGuideCommunity,“SpectralDistributionofaSampled1st-OrderLowpassFilteredWhiteNoise,”ElectronicsLetters,vol.17,pp.720-721,Sep.1981.6.C.A.Gobet,A.Knob,“NoiseAnalysisofSwitchedCapacitorNetworks,”IEEETrans.CircuitsandSystems,vol.cas-30,pp.37-43,Jan.1983.7.J.H.Fischer,“NoiseSourcesandCalculationTechniquesforSwitchedCapacitorFilters,”IEEEJ.Solid-StateCircuits,vol.sc-17,pp.742-752,Aug.1982.