CMOS-LEVEL-SHIFTERS

1TheUniversityofTexasatAustinEE382MClassNotesFoil#1/32EE-382MVLSI–IICMOSLEVELSHIFTERSSPRING2015GianGerosaTheUniversityofTexasatAustinEE382MClassNotesFoil#2/32OUTLINE•Motivation•BasicOperation•DesignEvolution•DesigningforCollapsiblePowerGridswithFIREWALLs•Multi-stageDesignforHighVoltage•Conclusion2TheUniversityofTexasatAustinEE382MClassNotesFoil#3/32MOTIVATIONSoCintegrationofmanyunrelatedfunctionsintheirownpower‘islands’.IntelZ2460ATOMSoCCPUaudiosouthcomplexsecurity2D/3DgraphicsImageSignalProcessordisplayvideoNCPLLsGPIOMIPIDDRGPIODDRDDRDDREMMCGPIODDRDDRclocksHDMIRumiZahir,HOTCHIPs#24,Aug.2012TheUniversityofTexasatAustinEE382MClassNotesFoil#4/32MOTIVATION–cnt’d•On-dievoltageregulationleadingtopower‘islands’thatcanhavedifferentvoltagelevels.•Powermanagementthatshutsfunctionalunitsoff.•Voltage-Frequencypairs;CPU’scanberuninseveraloperatingpointswhereitspowersupplyisadjustedtoreducepower:–lowestfrequency:100-600MHz–mediumfrequency:700-1500MHz–burstfrequency:1600–2500MHz•OFFchipdrivershavetosupportvariousvoltagelevelswhereasthecontrollerlogicispoweredbyalowervoltage:–LPDDR:1.25V–MIPI-display:1.25Vregulatedto0.4Vdifferential–HDMI-display3.3V–SDcards:2.85V–GPIO:1.25Vand1.80V3TheUniversityofTexasatAustinEE382MClassNotesFoil#5/32BASICOPERATION#1V_lowV_hi?TheUniversityofTexasatAustinEE382MClassNotesFoil#6/32BASICOPERATION#2V_lowV_hi•Willthiswork?AssumeV_low=0.8VandV_hi=1.2V.•WhatcanyousayaboutinvertersAandB,nor-gateC,nand-gateD?•Evenifyoucansizethegatestoworkcorrectly,whatcanyousayaboutV_hipower?•WhatifV_low=1.2VandV_hi=0.8V?Isthisok?ABCD4TheUniversityofTexasatAustinEE382MClassNotesFoil#7/32NOLEVELSHIFTERbetween2invertersTheUniversityofTexasatAustinEE382MClassNotesFoil#8/32DESIGN#1ainoutV_lowV_lowV_hiV_hiBAinABoutASSYMETRICALLATENCY:Notethatthehigh-to-lowdelayishigher.5TheUniversityofTexasatAustinEE382MClassNotesFoil#9/32DESIGN#1binoutV_lowV_lowV_hiV_hiBAinABoutAsymmetricaldelayissolvedwhilekeepingthedelayto2inversions.TheUniversityofTexasatAustinEE382MClassNotesFoil#10/32DESIGN#1cinoutImprovesthelow-to-hightransitionbypartiallyturningoffQ1.Q1inout_1aout_1bout_1c6TheUniversityofTexasatAustinEE382MClassNotesFoil#11/32DIFFERENTIALDESIGNS–part1-inoutV_hiV_hiin_bV_hiV_hiV_lowV_lowTheUniversityofTexasatAustinEE382MClassNotesFoil#12/32DIFFERENTIALDESIGN–part2-inoutV_hiV_hiin_bV_hiV_hi7TheUniversityofTexasatAustinEE382MClassNotesFoil#13/32RE-ARRANGINGleadstoDESIGN#2inoutV_lowV_lowV_hiV_hiV_hiCanberemovedTheUniversityofTexasatAustinEE382MClassNotesFoil#14/32DESIGN#2inoutV_lowV_lowV_hiV_hiV_hiABCDinABCDout8TheUniversityofTexasatAustinEE382MClassNotesFoil#15/32DESIGN#3:stateispreservedinV_hiinoutV_lowV_lowV_hiV_hiV_hiAddfullback-to-backinvertersforhighestNOISEimmunityattheexpenseofincreasedwrite-currentandtimetoflipthelatch.Inaddition,iftheV-lowpowerisremoved,thestateispreservedbytheV_hipoweredlatch.TheUniversityofTexasatAustinEE382MClassNotesFoil#16/32DESIGN#4a:ImprovingwritespeedinoutV_lowV_lowV_hiV_hiV_hi9TheUniversityofTexasatAustinEE382MClassNotesFoil#17/32DESIGN#4b:ImprovingwritespeedinoutV_lowV_lowV_hiV_hiV_hi•IsthestatestoredintheV_hiJAMlatchpreservedifV_lowisremoved?•Isthisabetterdesigncomparedto#4a?TheUniversityofTexasatAustinEE382MClassNotesFoil#18/32DESIGN#5:PreservingStateinoutV_lowV_lowV_hiV_hiV_hienableExpectthisdesigntoslowdown,why?Howcanyoumakethisdesignfaster?10TheUniversityofTexasatAustinEE382MClassNotesFoil#19/32DESIGN#6:PreservingStateinoutV_lowV_lowV_hiV_hiV_hienableTheUniversityofTexasatAustinEE382MClassNotesFoil#20/32PerformanceComparisoninDesignrisefall#378.3ps76.6ps#474.3ps74.1ps#581.4ps79.7ps#670.9ps69.0psT=70CV_low=0.7VV_hi=1.1V22nmCMOSdesign#4design#5design#3design#611TheUniversityofTexasatAustinEE382MClassNotesFoil#21/32ADDINGaFIREWALL•AllpriordesignsassumedthatneitherV_lownorV_hiarepowereddown.•WhatifV_lowispower-gatedandV_hiremainspoweredup?•WhathappenstotheoutputsoftheV_lowpowered(blue)logic?•WillthestateoftheV_hilogicbepreserved(evenifitremainspoweredup)?TheUniversityofTexasatAustinEE382MClassNotesFoil#22/32ADDINGaFIREWALLV_lowV_hienableenable_binenableout011110X01inoutV_hiinoutinenable_bout001100X1012TheUniversityofTexasatAustinEE382MClassNotesFoil#23/32ISOLATINGV_lowfromV_hi(whatfor?)V_hiV_lowV_lowinenableoutTheUniversityofTexasatAustinEE382MClassNotesFoil#24/32FIREWALL–drivesalowwhendisabled-inoutV_lowV_lowV_hiV_hiV_hiV_hienableNotethatenableneedstobegeneratedbyaV_hipoweredlogic.IsthisPFETneeded?13TheUniversityofTexasatAustinEE382MClassNotesFoil#25/32FIREWALL–drivesahighwhendisabled-inoutV_lowV_lowV_hiV_hiV_hiV_hienableNotethatenableneedstobegeneratedbyaV_hipoweredlogic.IsthisNFETneeded?TheUniversityofTexasatAustinEE382MClassNotesFoil#26/32WHATABOUTMUCHHIGHERV_hi?V_midV_lowenableinoutV_hiV_midenableoutinrailvoltsV_low0.75V_mid1.20V_hi1.80V_midV_lowenableinrailvoltsV_low0.75V_mid1.20V_hi1.80V_hioutenable14TheUniversityofTexasatAustinEE382MClassNotesFoil#27/32Multi-StageDesigninoutV_lowV_lowV_hiV_hiV_hiV_mid•TheV_hiandV_midtransistorsneedtobeableto‘handle’thehighervoltage(1.80Vinthiscase).•Nod