SoC设计方法与实现第十一章低功耗

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1、第十一章低功耗设计OutlineWhylowpowerSourcesofpowerconsumptionLowpowerdesignmethodologyLowpowertechniquesPoweranalysisandtoolsTrendsinthefutureWhyLowPowerPotablesystem-BatterylifetimeExample:mobilephone,PDA,DigitalcameraDesktops:highpowerconsumptionReliabilityandperformanceNeedexpensivec

2、hippackage,coolingsystemSeveraldeleteriouseffectsDecreasedreliabilityandperformanceIncreasedcost:packagingcostandcoolingsystemExceedpowerlimitsofthechip&systemPower,CostandHeatComponent:siliconandpackageIncreaseddiesize(widerpowerbusses)Needbetterthermalcapabilities(packagemate

3、rial)NeedbetterelectricalcapabilitiesSystem:CoolingandmechanicalsLargerfansOversizedpowersuppliesPowerlimitstothewall~1100Wdclimitfor110V/20AplugChallengeofDesignasProcessScalingOutlineWhylowpowerSourcesofpowerconsumptionLowpowerdesignmethodologyLowpowertechniquesPoweranalysisa

4、ndtoolsTrendsinthefutureSourceofPowerConsumptionDynamicpowerconsumptionStaticpowerconsumptionKeyareasofpowerconsumptioninSOCSourceofPowerDissipationinCMOSDevicesC=nodecapacitancesNsw=switchingactivities(numberofgatetransitionsperclockcycle)F=frequencyofoperationVDD=supplyvoltag

5、eQsc=chargecarriedbyshortcircuitcurrentpertransitionIleak=leakagecurrentStaticPowerConsumption:Leakagecurrents:Sub-thresholdcurrent(I2)GateleakageGatetunnelling(I4)Gateinduceddrainleakage(I3)pn-junctionreversecurrent(I1)DCcurrentsAnalogcircuit:sense-amps,pull-upsStatedependentL

6、eakagevs.ProcessWhatwillbethedominatedleakagecurrent?LongChannel(L>1um)VerysmallleakageShortchannel(L>180nm,tox>30A)SubthresholdleakageVeryshortchannel(L>90nm,tox>20A)subthreshold+gateleakageNano-scaled(L<90nm,Tox<20A)Subthreshold+gate+junctionleakageSub-thresholdleakagecurrent

7、HasbecomequiteimportantwithtechnologyscalingGateleakagecurrentIsbecomingimportantwithshrinkingdevicedimensionsPNjunctionleakagecurrentNegligibleOutlineWhylowpowerSourcesofpowerconsumptionLowpowerdesignmethodologyLowpowertechniquesLowpoweranalysisandtoolsTrendsinthefutureLowPowe

8、rDesignMethodologyMustknowyoursystemMaximizetheperform