full-chip transient temperature analysis
TRANSCRIPT
Transient Temperature AnalysisTransient Temperature AnalysisTransient Temperature AnalysisTransient Temperature Analysis
Rajit Chandra, Ph.D.
Gradient Design Automation
10/23/200610/23/2006 22
Trends in mixed signal designsTrends in mixed signal designsTrends in mixed signal designsTrends in mixed signal designs
Transitory failure conditions caused by higher temperature distributions
!!!!Trends in integration – analog, digital, systems-in- package, dense power distribution
High temperature can momentarily reduce power drive causing malfunction
!!!!Reliable power drive requirements for safety critical applications
Max device temperature can exceed spec momentarily causing permanent damage
!!!!Switching power sources affect device, and die temperatures
Slow time-varying power source performance affected by transient temperatures that steady state analysis cannot detect
!!!!More designs with switching high power drivers (smart power chips, automotive, high-speed communications, …)
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Steady state versus transient analysisSteady state versus transient analysisSteady state versus transient analysisSteady state versus transient analysis
" Steady state temperature analysis based on average power " Faster digital switching
power sources affected not by instantaneous but by average temperatures
" Transition time of power transistors compare with rate of temperature response of die
" Electrical response is affected by instantaneous temperatures, causing possible malfunctions
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Temperature at PTAT
PTAT response with transient temperatures
Effect of transient temperature across die
PTA
T re
spon
se
Instance temperature based response
Expe
cted r
espon
se with
unifo
rm te
mperat
ure
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Motivation for full chip transient thermal analysis:Motivation for full chip transient thermal analysis:Motivation for full chip transient thermal analysis:Motivation for full chip transient thermal analysis:
" Duty cycle of power sources affect rate of heat dissipation
" Several thermal time constants are involved for example:
" Individual device temperatures peak ~ 100’s of us
" Die temperatures ~ ms
" Package and substrate ~ seconds
" Accumulated heat can cause instantaneous peak junction temperature to be much higher than steady state values
" Temperatures can exceed spec for devices
" Cause problems with circuit performance, reliability, burn out
Max Power, Temperature
Time
Junction temperature!ON
Period
OFF
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Effects of temperature transientsEffects of temperature transientsEffects of temperature transientsEffects of temperature transients
Peak instantaneous temperatures surpassing tolerance thresholds
!!!!Duty cycle of instance power waveform
Deviation from expected electrical behavior of device e.g: signal timing, power drive, signal wave shape
!!!!Device response time comparable to temperature time constant
Parametric failures!!!!Temperature difference across circuits
Electromigration and reliability!!!!Joule (interconnect heating)
Performance degradation and malfunctions
!!!!Device self-heating
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Challenges of transient thermal analysisChallenges of transient thermal analysisChallenges of transient thermal analysisChallenges of transient thermal analysis
" Existing transient temperature analysis methods:
" Fully coupled electrical and thermal simulation
" Long run times, does not scale to full chip analysis, closely tied with circuit simulator
" Relaxation methods with separate but synchronized thermal
and electrical simulation" Accurate, scaleable in performance, can be integrated with
multiple circuit simulators
" Allows mixed level circuit descriptions, handles digital blocks,
transistor circuits and architectural evaluations prior to final
layout
" For present day design complexity fully coupled analysis tools are too slow and restrictive – relaxation method is a better choice
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Requirements for full chip transient analysisRequirements for full chip transient analysisRequirements for full chip transient analysisRequirements for full chip transient analysis
" Compute and track rates of temperature changes within dieCompute and track rates of temperature changes within dieCompute and track rates of temperature changes within dieCompute and track rates of temperature changes within die
" Detect temperature limits specified by usersDetect temperature limits specified by usersDetect temperature limits specified by usersDetect temperature limits specified by users
" Update instance power with temperature changeUpdate instance power with temperature changeUpdate instance power with temperature changeUpdate instance power with temperature change
" Update instance temperatures based on self & heat couplingUpdate instance temperatures based on self & heat couplingUpdate instance temperatures based on self & heat couplingUpdate instance temperatures based on self & heat coupling
" Model time varying waveform for power sourcesModel time varying waveform for power sourcesModel time varying waveform for power sourcesModel time varying waveform for power sources
" Determine critical time interval for temperature evaluationDetermine critical time interval for temperature evaluationDetermine critical time interval for temperature evaluationDetermine critical time interval for temperature evaluation
" Manage and synchronize transient electroManage and synchronize transient electroManage and synchronize transient electroManage and synchronize transient electro----thermal simulationthermal simulationthermal simulationthermal simulation
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Support fineSupport fineSupport fineSupport fine----grain analysis for accuracy grain analysis for accuracy grain analysis for accuracy grain analysis for accuracy –––– of hotspot of hotspot of hotspot of hotspot magnitude and locationmagnitude and locationmagnitude and locationmagnitude and location
Coarse-grain Fine-grain
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Example Example Example Example testcasetestcasetestcasetestcase" Based on a customer donated design:
" 3 x 4 mm die with power transistor & PTAT circuit
" 0.35u technology node
" 0.6mm X 0.7mm power sources
" 3 metal layers, pad layer
" Power: Trapezoidal pulse train, rise and fall time:0.1mm, width: 1ms, period:5ms, max power:22W
" This example demonstrates:
-Transient temperature analysis
-Times at which power source reaches
specified temperatures
-Transitory temperature effect
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Snapshots of temperature profile of power source Snapshots of temperature profile of power source Snapshots of temperature profile of power source Snapshots of temperature profile of power source
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Transient temperature analysis flowTransient temperature analysis flowTransient temperature analysis flowTransient temperature analysis flow
Time VaryingPower Sources
PowerSources
DesignLayout
PackageModel
TemperatureSpecs
TechnologyFile
CircuitFire
Transient Temperature Analysis
controlfile
device models
Netlistwith
temperatures
Circuit simulator
Report: TemperatureSpecification
Violations
Instancetemperatures
at critical time intervals
Even
t sy
nchr
oniz
er
InstancePower
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Technology featuresTechnology featuresTechnology featuresTechnology features
"High capacity, high resolution
" Incorporates package and boundary conditions
"True 3-D temperature analysis
"Detail temperature for all design objects on all layers
"Comprehensive data visualization
" Interoperability with current tools & flows
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Control parameters and output dataControl parameters and output dataControl parameters and output dataControl parameters and output data" Control file allows runtime/accuracy tradeoff
" Parameters to define accuracy
" Parameters for adaptive grid based on
"Power source geometries, thermal and power gradients
"Output:
"Temperature within die: 3D visualization with archives
"Temperate & power per instance
"Temperature & power per wire shape
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User defined analysis featuresUser defined analysis featuresUser defined analysis featuresUser defined analysis features
"Set max limit of instance temperature"Set max temperature difference between
instances"Save and run from specified state and time"Query time stamp of instance temperatures"Warning and error reports for specified limits"User definable
"Waveform viewer plug-ins"Temperature archives for detailed analysis
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Use models:Use models:Use models:Use models:
"Batch mode" Command file, input data files, archived data
useful for examining with interactive graphics for large designs
" Interactive mode (Tcl based)" Define power source parameters, change
locations rotation" Redefine power waveform or temperature-
power lookup" Evaluate material thermal parameters and
package parameters" Interactive mode is ideal for design exploration!
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Ambient temperatures can be harsh Ambient temperatures can be harsh Ambient temperatures can be harsh Ambient temperatures can be harsh –––– need to need to need to need to consider detailed package modelsconsider detailed package modelsconsider detailed package modelsconsider detailed package models
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Accuracy of package models: Accuracy of package models: Accuracy of package models: Accuracy of package models: CircuitFireCircuitFireCircuitFireCircuitFire----FlomericsFlomericsFlomericsFlomerics interface interface interface interface ----a bridge between package and design worldsa bridge between package and design worldsa bridge between package and design worldsa bridge between package and design worlds
" Accuracy of package thermal prediction can be improved by coupling 3-D package simulation with FireBolt
" Allows inclusion of complex cooling mechanism
DesignPackaging
CircuitFireFlomerics Design
Package model Layout
Die thermal profile
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Takes package and ambient into accountTakes package and ambient into accountTakes package and ambient into accountTakes package and ambient into account
Air flow
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Validation of ResultsValidation of ResultsValidation of ResultsValidation of Results
" Measurement on silicon with thermal diode and different package models
81.888127.82.12Slug2
82.968228.22.13Slug1
86.978629.42.18Epad2
87.918729.72.19Epad1
GDA�s Tj (°C) average diode temperature
Measured Tj (°C) measured using diode
θJA (K/W)Power (W)Test Case
" Measurement on silicon with PTAT circuit: Thermal analysis results annotated into Spice simulator and validated with lab measurements
" Correlation with infra red camera and GUI temperature distribution
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SummarySummarySummarySummary
" Mixed signal designs use power devices for commercial and industrial use
" Higher levels of device integration and power densities cause steep temperature variations in many applications
" Transitory temperature profiles can cause performance and reliability issues, or even permanent device failure
" CircuitFire provides a full chip level solution with package parameters that can be integrated with circuit simulators and layout editors