B

---

Environment Variables

---

The following sections describe the environment variables used in the electromigration flow:

• elec.gui
• elec.results
• ei.dataSet
• ei.setup
• msps.layout
• layoutEAD
• layoutEAD.calc
• layoutEAD.em
• layoutEAD.gui
• layoutEAD.pex
• layoutEAD.solver
• p2t

elec.gui

The following environment variables provide default values to the EAD Setup form in Design Environment XL:

• createVoltageConstraints
• customVoltageConstraintFunc
• customVminCalc
• customVmaxCalc
• enableCustomVminVmaxCalc
• enableEADMode
• saveAll
• useHierarchyLevel
• hierarchyLevel
• enableIdc
• idcScaleFactor
• enableIavg
• iavgScaleFactor
• enableIsignal
• saveWaveforms
• clipWaveforms
• clipFrom
• clipTo
• showOnlyTopLevelNets
• skipLibListForDataset
• vdrcPerf
• vdrcPerfSigCount
• vdrCsvDatasetDir
• vdrCsvDatasetFileSuffix
• vdrCsvDatasetNameSuffix
• warnOnCacheEdit
• warnOnCacheSave
• warnOnDatasetOverwrite

createVoltageConstraints

elec.gui createVoltageConstraints boolean { t | nil }

Description

Specifies whether to create voltage constraints. The default value is nil, which indicates that voltage constraints are not created. Set this value to t, if you want to create voltage constraints.

GUI Equivalent

EAD Setup – Voltage Dependent Rules – Create voltage constraints

Examples

envGetVal("elec.gui" "createVoltageConstraints")

envSetVal("elec.gui" "createVoltageConstraints" 'boolean t)

Related Topics

EAD Setup

customVoltageConstraintFunc

elecVdrCreateConstraints

elecVdrCreateDeltaV

customVoltageConstraintFunc

elec.gui customVoltageConstraintFunc string nameOfTheUserDefinedFunction

Description

Specifies the name of the user-defined function to be called to create deltaVoltage and voltageSyncedNet constraints.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "customVoltageConstraintFunc")

envSetVal( "elec.gui" "customVoltageConstraintFunc" 'string "userDefinedElecFunc")

Related Topics

elecVdrCreateConstraints

elecVdrCreateDeltaV

createVoltageConstraints

customVmaxCalc

Specifies the name of a user-defined SKILL procedure to be used in the calculation of the maximum voltage value during simulation.

elec.gui customVmaxCalc string "demoCalcVmax"

envSetVal("elec.gui" "customVmaxCalc" 'string "demoCalcVmax")

""

For more information, see Customizing the Calculation of Minimum and Maximum Voltages in the Virtuoso Voltage Dependent Rules Flow Guide.

customVminCalc

Specifies the name of a user-defined SKILL procedure to be used in the calculation of the minimum voltage value during simulation.

elec.gui customVminCalc string "My_Vmin"

envSetVal("elec.gui" "customVminCalc" 'string "My_Vmin")

""

For more information, see Customizing the Calculation of Minimum and Maximum Voltages in the Virtuoso Voltage Dependent Rules Flow Guide.

enableCustomVminVmaxCalc

Enables or disables the feature to use custom SKILL procedures for the calculation of the minimum and maximum voltage values to be used in the voltage dependent rules flow.

elec.gui enableCustomVminVmaxCalc boolean t

envSetVal("elec.gui" "enableCustomVminVmaxCalc" 'boolean t)

t

nil

nil

Related Variables:

• customVminCalc
• customVmaxCalc

For more information, see Customizing the Calculation of Minimum and Maximum Voltages in the Virtuoso Voltage Dependent Rules Flow Guide.

enableEADMode

Enables or disables the EAD mode for the current design. When the EAD mode is enabled, the current data is saved with the simulation results. This data is further used in electromigration analysis.

EAD mode can be enabled in SKILL scripts using the following codes:

sess=axlGetWindowSession()

sdb=axlGetMainSetupDB(sess)

elecSetup=axlSDBGetExtension(sdb "ElectricalSetup")

when(elecSetup>0

  design=axlSDBGetChild(elecSetup "Design")

  elecMode=axlSDBGetChild(design "ElectricalMode")

  axlSDBSetValue(elecMode "True")

)

You can use the following command to disable EAD mode:

axlSDBSetValue(elecMode "False")

elec.gui enableEADMode boolean t

envSetVal("elec.gui" "enableEADMode" 'boolean t)

t

nil

nil

saveAll

Specifies if the current data is to be saved for all the signals in the selected design.

elec.gui saveAll boolean t

envSetVal("elec.gui" "saveAll" 'boolean t)

t

nil

t

useHierarchyLevel

Specifies if the current data is to be saved only upto a given hierarchy level in the selected design.

elec.gui useHierarchyLevel boolean t

envSetVal("elec.gui" "useHierarchyLevel" 'boolean t)

t

nil

t

hierarchyLevel

Specifies the level of hierarchy upto which the current data is to be saved for all the signals.

elec.gui hierarchyLevel int 5

envSetVal("elec.gui" "hierarchyLevel" 'int 4)

99

enableIdc

Saves the DC current data for the specified signals with the results database. In this case, ensure that DC analysis has been enabled for the test.

elec.gui enableIdc boolean t

envSetVal("elec.gui" "enableIdc" 'boolean t)

t

nil

t

idcScaleFactor

Specifies the scale factor for the DC current data. This scale factor is used to scale the current data only while transferring the currents from schematic to the layout view.

elec.gui idcScaleFactor float 1.0 

envSetVal("elec.gui" "idcScaleFactor" 'float 2.0)

1.0

enableIavg

Saves the average current data for the specified signals with the simulation results. In this case, ensure that transient analysis has been enabled for the test.

elec.gui enableIavg boolean t

envSetVal("elec.gui" "enableIavg" 'boolean t)

t

nil

t

iavgScaleFactor

Specifies the scale factor for the average current data.

elec.gui iavgScaleFactor float 1.0 

envSetVal("elec.gui" "iavgScaleFactor" 'float 2.0)

1.0

enableIsignal

Saves the transient waveform data for the selected signals so that it can be used for dynamic EM analysis.

elec.gui enableIsignal boolean t

envSetVal("elec.gui" "enableIsignal" 'boolean t)

t

nil

nil

saveWaveforms

Saves the current waveforms with the simulation data to disk so that it can be processed later while performing electromigration checks.

elec.gui saveWaveforms boolean t

envSetVal("elec.gui" "saveWaveforms" 'boolean t)

t

nil

t

clipWaveforms

If you choose to save the current waveforms with the simulation data, this option specifies whether the currents are to be compiled for a specific time interval or for the complete simulation run.

The time interval can be specified using the clipFrom and clipTo environment variables.

elec.gui clipWaveforms boolean nil

envSetVal("elec.gui" "clipWaveforms" 'boolean t)

t

nil

nil

clipFrom

Specifies a start time of the time interval for which the waveform clip of the current data is to be saved.

elec.gui clipFrom string ""

envSetVal( "elec.gui" "clipFrom" 'string "10u")

""

clipTo

Specifies an end time of the time interval for which the waveform clip of the current data is to be saved.

elec.gui clipTo string "" 

envSetVal("elec.gui" "clipTo" 'string "40u")

""

skipLibListForDataset

elec.gui skipLibListForDataset string space-separatedLibraryNames

Description

Specifies the space-separated library names for which you do not want to create datasets. The default value is "", which indicates that datasets are created for all libraries.

You can also use regular expressions. The following example uses regular expressions to skip dataset creation for all libraries whose name start with testLib and myLib:

envSetVal("elec.gui" "skipLibListForDataset" 'string "testLib* myLib*")

GUI Equivalent

None

Examples

envGetVal("elec.gui" "skipLibListForDataset")

envSetVal("elec.gui" "skipLibListForDataset" 'string "myLib1 myLib2")

vdrcPerf

elec.gui vdrcPerf boolean { t | nil }

Description

Specifies whether to select All in the DUT Masters drop-down list.

The default is nil, which indicates that the current DUT is selected in the DUT Masters drop-down list. If a DUT master has constraint cache, viewing results also opens the constraints cache associated with the DUT master. Therefore, opening results may take a lot of time for large datasets.

When you set this environment variable to t, All is selected in the DUT Masters drop-down list and opening results does not open constraint cache. This helps in improving performance. Note that all signals are still saved.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "vdrcPerf")

envSetVal("elec.gui" "vdrcPerf" 'boolean t)

vdrcPerfSigCount

elec.gui vdrcPerfSigCount int numberOfSignals

Description

Specifies the threshold count of signals, exceeding which all instances for a DUT master are listed in DUT Instance drop-down list, even if an instance has no signals saved to them.

When number of signals is very large, it takes time to determine which instances have signals saved to them.

The default value is 10000, which indicates that if there are more than 10000 signals saved, all instances will be listed in the DUT Instance drop-down list, including the ones that do not have any signals.

If the number of signals saved are less than the specified value, only the instance that have at least one signal saved are displayed in the DUT Instance drop-down list.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "vdrcPerfSigCount")

envSetVal("elec.gui" "vdrcPerfSigCount" 'int 30000)

vdrCsvDatasetDir

elec.gui vdrCsvDatasetDir string pathToTheDirectoty

Description

Specifies the path to the directory where the edited simulation dataset is saved as the CSV file. The default is ".", which indicates that the file is saved in the current working directory.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "vdrCsvDatasetDir")

envSetVal("elec.gui" "vdrCsvDatasetDir" 'string "/home/user/simulation")

vdrCsvDatasetFileSuffix

elec.gui vdrCsvDatasetFileSuffix string suffixOfTheCSVFile

Description

Specifies the suffix of the CSV file containing information about the edited simulation dataset that is being saved as the CSV dataset. The default is "csv", which indicates that the CSV file is saved with the suffix csv.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "vdrCsvDatasetFileSuffix")

envSetVal("elec.gui" "vdrCsvDatasetFileSuffix" 'string "testCSV")

vdrCsvDatasetNameSuffix

elec.gui vdrCsvDatasetNameSuffix string suffixOfTheDatasetName

Description

Specifies the suffix to be added to the name of the CSV dataset. The default is "csv", which indicates that the name of the CSV Dataset is saved with the suffix csv.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "vdrCsvDatasetNameSuffix")

envSetVal("elec.gui" "vdrCsvDatasetNameSuffix" 'string "csvDataset")

showOnlyTopLevelNets

elec.gui showOnlyTopLevelNets boolean { t | nil }

Description

Specifies whether to display only top-level nets for Vmin and Vmax calculations in the simulation datasets on the VDR Dataset form. The default is nil, which indicates that all nets are displayed.

GUI Equivalent

None

Examples

envGetVal("elec.gui" "showOnlyTopLevelNets")

envSetVal("elec.gui" "showOnlyTopLevelNets" 'boolean t)

warnOnCacheEdit

Specifies if a warning message is to be displayed before making the constraint view editable while creating a dataset in ADE Assembler.

elec.gui warnOnCacheEdit boolean t 

envSetVal("elec.gui" "warnOnCacheEdit" 'boolean t)

t

nil

t

warnOnCacheSave

Specifies if a warning message is to be displayed while saving a dataset in the constraint view.

elec.gui warnOnCacheSave boolean t 

envSetVal("elec.gui" "warnOnCacheSave" 'boolean t)

t

nil

t

warnOnDatasetOverwrite

Specifies if a warning message needs to be displayed when an existing dataset is being overwritten by the dataset being saved.

elec.gui warnOnDatasetOverwrite boolean t

envSetVal("elec.gui" "warnOnDatasetOverwrite" 'boolean t)

t

nil

t

elec.results

• dcResultName
• tranResultName

dcResultName

Specifies the result name for DC data that can be passed to the selectResult OCEAN command to access terminal currents. If not set, the EAD first looks for "dcOp". If that too is not found, uses "dc"as the result name.

elec.results dcResultName string ""

envSetVal("elec.results" "dcResultName" 'string "")

""

tranResultName

Specifies the result name for transient data that can be passed to the selectResult OCEAN command to access terminal currents. If not set, the tool uses "tran".

elec.results tranResultName string ""

envSetVal("elec.results" "tranResultName" 'string "")

""

ei.dataSet

• excludeCurrentsInCI
• storeRelativePaths
• transferPerf

excludeCurrentsInCI

Specifies if the current data is to be saved as part of the constraint view where a dataset is being saved. By default, when a dataset is saved in the constraint view, the current data is not saved in it. Instead, only the paths to the simulation results directory are saved.

ei.dataSet excludeCurrentsInCI boolean t

envSetVal("ei.dataSet" "excludeCurrentsInCI" 'boolean t)

t

nil

t

storeRelativePaths

Saves the paths of the results database and the simulation directory as relative paths. By default, absolute paths are saved for these directories.

ei.dataSet storeRelativePaths boolean t

envSetVal("ei.dataSet" "storeRelativePaths" 'boolean t)

t

nil

nil

transferPerf

Enables you to improve the performance when updating electrical data. By default, this environment variable is set to t so that you do not face any performance-related issues when updating electrical data. However, if this causes any issues in creating datasets, you can set it to nil.

ei.dataSet transferPerf boolean t

envSetVal("ei.dataSet" "transferPerf" 'boolean t)

t

nil

t

ei.setup

• enableWorstCaseDatasetForVoltages
• expandIteratedInstancesForCurrents
• expandIteratedInstancesForVoltages

enableWorstCaseDatasetForVoltages

ei.setup enableWorstCaseDatasetForVoltages boolean {t | nil}

Description

Specifies whether to create a single worst-case simulation voltage dataset having worst Vmin and Vmax values for all nets. The dataset is saved in the constraint view.

Worst Vmin value is the minimum voltage value across all corners, sweep points, and DUT instances. Worst Vmax value is the maximum voltage value across all corners, sweep points, and DUT instances.

The dataset with the net names and worst voltage values (Vmin and Vmax) are displayed in the Simulation Dataset tab of the VDR Dataset form.

The default value is nil, which indicates that simulation datasets are created for unique combinations of values in the Point, Corner, DUT Masters, and DUT Instance drop-down lists.

This environment variable works only if the environment variable ei.dataSet excludeCurrentsInCI is set to nil.

GUI Equivalent

None

Examples

envGetVal("ei.setup" "enableWorstCaseDatasetForVoltages")

envSetVal("ei.setup" "enableWorstCaseDatasetForVoltages" 'boolean t)

Related Topics

excludeCurrentsInCI

Creating Datasets

Viewing Simulation Datasets

expandIteratedInstancesForCurrents

Specifies whether iterated instances are to be expanded when saving the current data. For example, if there is a hierarchical instance terminal /I1<0:2>/I2<0:1>/OUT, the current data will be saved as described below.

When the expandIteratedInstancesForCurrents variable is set to t, the data would be saved for the terminals of all the iterated instances:

/I1<0>/I2<0>/OUT
/I1<1>/I2<0>/OUT
/I1<2>/I2<0>/OUT
/I1<0>/I2<1>/OUT
/I1<1>/I2<1>/OUT
/I1<2>/I2<1>/OUT

When the expandIteratedInstancesForCurrents variable is set to nil, only the first instance of the iterated instance is taken into account, ignoring the rest. In this example, the current would be saved only for/I1<0>/I2<0>/OUT.

ei.setup expandIteratedInstancesForCurrents boolean t

envSetVal("ei.setup" "expandIteratedInstancesForCurrents" 'boolean t)

t

nil

nil

expandIteratedInstancesForVoltages

Specifies whether iterated instances are to be expanded when saving the voltage data. For example, if there is a hierarchical instance voltage /I1<0:2>/I2<0:1>/net4, the voltage data will be saved as described below.

When the expandIteratedInstancesForVoltages variable is set to t, the data would be saved for the nets connected toall the iterated instances:

/I1<0>/I2<0>/net4
/I1<1>/I2<0>/net4
/I1<2>/I2<0>/net4
/I1<0>/I2<1>/net4
/I1<1>/I2<1>/net4
/I1<2>/I2<1>/net4

When the expandIteratedInstancesForVoltages variable is set to nil, only the first instance of the iterated instance is taken into account, ignoring the rest. In this example, the voltage would be saved only for/I1<0>/I2<0>/net4.

ei.setup expandIteratedInstancesForVoltages boolean nil

envSetVal("ei.setup" "expandIteratedInstancesForVoltages" 'boolean nil)

t

nil

nil

Also see: expandIteratedInstancesForCurrents

msps.layout

• expandSchematicDevices
• fingeringNames
• ignoreBackAnnotatedDummyDevices
• includeLayoutParasitics
• includeSchematicEstimates
• individualInstCdfCallbacks
• mfactorNames
• mixSchEstWithLayoutParasitics
• netlistView
• referenceNet

individualInstCdfCallbacks

When expanding an m-factor or fingered device in the parasitic/LDE view, the tool executes a CDF callback associated with that device. This variable specifies if the CDF callback is to be executed for each instance of a device or only once for a device.

By default, this variable is set to nil and while building a parasitic/LDE view, Virtuoso does not execute the CDF callback for each instance of a device. Instead, it executes the callback only once for a device and the result is applicable to all the instances. This helps in optimizing the build process.

To execute the callback for each cell instance separately, set this variable to t.

msps.layout individualInstCdfCallbacks boolean nil

envSetVal("msps.layout" "individualInstCdfCallbacks" 'boolean nil)

t

nil

nil

layoutEAD

• auxSearchPaths
• checkEM
• defaultJobPolicy
• doAutoLayerMapping
• excludedNets
• excludedNetsExceptions
• extractConnectivity
• extractNetsWithConstraints
• flattenOtherInstances
• highlightNetShapes
• includeEmptyNets
• loadSubconductorLayers
• processSettings
• processStrappedMosfets
• resistancePathLimit
• stampNullNetTiles
• updateMode
• updateStyle
• useCorner
• useSetup
• xlNetsOnly

auxSearchPaths

Specifies additional directories that are to be searched for EAD setup and process settings files.

layoutEAD auxSearchPaths string "path"

envSetVal("layoutEAD" "auxSearchPaths" 'string "path")

string

checkEM

Disables EM checking and display for subsequent changes to the layout. EM checking and all EM-related options are disabled.

In .cdsenv:
	layoutEAD checkEM boolean t
In .cdsinit or the CIW:
	envSetVal("layoutEAD" "checkEM" 'boolean t)
Valid Values:
	t	EM checking and options are enabled.
	nil	EM checking and options are disabled.
Default Value:	t
GUI Equivalent:	Command: Run EM Check – Disable EM Checker (EAD Browser toolbar)

defaultJobPolicy

Specifies the default job policy to be used to run extraction.

layoutEAD defaultJobPolicy string "localhost"

envSetVal("layoutEAD" "defaultJobPolicy" 'string "localhost")

localhost

doAutoLayerMapping

Controls whether to automatically map a design layer to a layer in the EAD technology file if both the layers have the same name.

For example, if you set this environment variable to t, and both the design and EAD technology file have a layer named, 'Metal1', these layers will be automatically mapped without any explicit mapping defined in the EAD setup.

layoutEAD doAutoLayerMapping boolean t

envSetVal("layoutEAD" "doAutoLayerMapping" 'boolean t)

t

nil

t

excludedNets

Lists the nets that are to be excluded from parasitic extraction. Use this to specify any net (complete, incomplete, power, etc) that you do not want to extract.

layoutEAD excludedNets string "string"

envSetVal("layoutEAD" "excludedNets" 'string "string")

string

excludedNetsExceptions

Lists the nets that are exceptions to the list of excluded nets specifed using excludedNets. Basically, the extraction setting is overriden for the nets given in this list and they are displayed or extracted.

layoutEAD excludedNetsExceptions string "string"

envSetVal("layoutEAD" "excludedNetsExceptions" 'string "string")

string

extractConnectivity

Controls whether layout shapes that are not explicitly assigned to a net, but need to be extracted with a net for accurate extraction results, are assigned the same net as any shape they touch. This assignment is used for parasitic extraction purposes only.

When C extraction is done, any shape with no net is treated as connected to ground.

Important Points to Note

• This variable is helpful in assigning nets to the null net shapes only in Pcells. It does not stamp null net shapes with sources other than Pcells. For non-Pcell shapes, you can use stampNullNetTiles.
• By setting this variable to none, you can prevent the extraction of incorrect shapes when the device instances, which are not to be extracted, are not distinguishable from the interconnect. Therefore, it is recommended to be careful when changing the value to "pcells".
• If your design have guard rings, set this variable to none.
• This variable does not assign nets to the null net shapes on the derived layers or the local interconnect layers.
  

  In .cdsenv:
  	layoutEAD extractConnectivity cyclic "pcells"
  In .cdsinit or the CIW:
  	envSetVal("layoutEAD" "extractConnectivity" 'cyclic "pcells")
  Valid Values:
  	"pcells"	Net assignment is performed only for null net shapes in Pcell masters
  	"none"	No net assignment is performed
  Default Value:	"pcells"
  GUI Equivalent:	None

Also see: stampNullNetTiles

extractNetsWithConstraints

Controls extraction of nets displayed in the EAD Browser. If this environment variable is set to t, the EAD Browser shows only those nets that have an EAD constraint defined on them. If the EAD Browser is already open and an EAD constraint is added to or deleted from a net, the Summary Pane is dynamically updated to show or hide that net.

layoutEAD extractNetsWithConstraints boolean t

envSetVal("layoutEAD" "extractNetsWithConstraints" 'boolean t)

t

nil

nil

flattenOtherInstances

Specifies whether the interconnect instances in the layout need to be flattened.

layoutEAD flattenOtherInstances boolean t

envSetVal("layoutEAD" "flattenOtherInstances" 'boolean t)

t

nil

nil

highlightNetShapes

Controls which types of net shapes (see hierarchyShapeType) are highlighted in the layout canvas when you click a net in the EAD Browser.

layoutEAD highlightNetShapes string "rb"

envSetVal("layoutEAD" "highlightNetShapes" 'string "rb")

string

rb

includeEmptyNets

Enables or disables display of empty nets, that is, the nets without any terminal, instance terminal, shape, or via on them, in the Summary pane of the EAD Browser.

layoutEAD includeEmptyNets boolean t

envSetVal("layoutEAD" "includeEmptyNets" 'boolean t)

t

nil

t

loadSubconductorLayers

Controls whether to include the sub_conductor layers in the ICT file. When included, the sub_conductor layers are available to create the mapping from Virtuoso layers to ICT layers in the EAD Process Settings form. Any geometry mapped to a sub_conductor layer is extracted according to the corresponding parameters in the ICT file. When not included, only the parent conductor layer is available for mapping and extraction.

layoutEAD loadSubconductorLayers boolean t

envSetVal("layoutEAD" "loadSubconductorLayers" 'boolean t)

t

nil

t

processSettings

Specifies the process settings file to be used in the current session.

layoutEAD processSettings string "file_name"

envSetVal( "layoutEAD" "processSettings" 'string "file_name")

string

processStrappedMosfets

EAD splits the current across multiple fingers of a transistor except when the transistor Pcell source or drain terminals are strapped together inside the Pcell. In that case, there is only one terminal defined for source and drain, respectively. When transferring the currents for EM analysis, EAD assigns all the current to the device terminal, which may not be correct. Set this variable to t to force EAD to split the current evenly between the fingers.

layoutEAD processStrappedMosfets boolean t

envSetVal( "layoutEAD" "processStrappedMosfets" 'boolean t)

t

nil

resistancePathLimit

Specifies the maximum number of resistance paths to evaluate and show in the EAD Browser.

layoutEAD resistancePathLimit int 100

envSetVal( "layoutEAD" "resistancePathLimit" 'int 100)

int

100

stampNullNetTiles

Specifies whether shapes that are not assigned to a net in the layout will be extracted because they physically connect to some shape other that does have a net.

Setting this variable to t is particularly helpful on layouts that contain subcells with only routing shapes (no devices).

During C extraction, any shape with no net is treated as connected to ground.

layoutEAD stampNullNetTiles boolean t

envSetVal("layoutEAD" "stampNullNetTiles" 'boolean t)

t

nil

t

Also see: extractConnectivity

updateMode

Specifies whether the extraction and EM checking results displayed in the EAD Browser are updated automatically as the layout is altered, or manually by clicking the Update Parasitics & EM button in the EAD Browser toolbar.

In .cdsenv:
	layoutEAD updateMode cyclic "manual"
In .cdsinit or the CIW:
	envSetVal("layoutEAD" "updateMode" 'cyclic "manual")
Valid Values:
	manual	Extraction and EM checking are run manually
	auto	Extraction and EM checking are run automatically
Default Value:	manual
GUI Equivalent:	Update Parasitics & EM – Manual Update Mode and Automatic Update Mode (EAD Browser toolbar)

updateStyle

Specifies whether parasitic extraction is performed continuously, in discrete steps, or only after the current action completes.

layoutEAD updateStyle cyclic "discrete"

envSetVal("layoutEAD" "updateStyle" 'cyclic "discrete")

discrete

continuous

actionComplete

discrete

useCorner

Specifies the extraction corner which is mapped to an ICT file or eadTechFile to be used for extraction and the source of the EM models to be used for EM Checking. This variable is used to initialize EAD in non-GUI flows, such as the pre-EM flow.

layoutEAD useCorner string "C0"

envSetVal("layoutEAD" "useCorner" 'string "C0")

string

useSetup

Specifies the name of the file containing the setup options.

layoutEAD useSetup string "path"

envSetVal("layoutEAD" "useSetup" 'string "path")

string

"./cadence/dfII/EAD/1/setup/gpdk45.ini"

xlNetsOnly

Specifies that EAD examines only those nets that are part of an OpenAccess design.

layoutEAD xlNetsOnly boolean t

envSetVal("layoutEAD" "xlNetsOnly" 'boolean t)

t

nil

t

layoutEAD.calc

showEstimatedResistance

showEstimatedResistance

layoutEAD.calc showEstimatedResistance boolean {t | nil}

Description

Specifies whether to display the Est. Resistance column in the results table of the EM Calculator.

The default value is nil, which indicates that the Est. Resistance column is hidden.

The Est. Resistance column displays the estimated resistance of the layer.

Resistance of a metal layer depends on the Length, Width, and EM Temperature fields, whereas resistance of a via layer depends on the Via Type, Cuts, and EM Temperature fields.

If the Length field is specified as a condition, for example:

• L < 5 or L <= 5, the length is considered as 5 when calculating estimated resistance.
• L > 5 or L >= 5, the length is considered as 5 when calculating the estimated resistance.
• 5 < L < 7 or 5 <= L <= 7, the length is considered as (5+7)/2 when calculating the estimated resistance.

GUI Equivalent

The Est. Resistance column in the results table of EM Calculator.

Examples

envGetVal("layoutEAD.calc" "showEstimatedResistance")

envSetVal("layoutEAD.calc" "showEstimatedResistance" 'boolean t)

Related Topics

Results Table

layoutEAD.em

• autoDatasetCustomProc
• autoDatasetDeviceLengthPropList
• autoDatasetMacroProp
• autoDatasetDeviceWidthPropList
• autoDatasetDistributionMethod
• adjustedCurrentMsgRelTol
• currentDensityMPVDefault
• customSHESetupFile
• cdfPercentage
• computeIRDropWhenLoadingSetup
• checkResWidthAndEMLength
• defaultCurrent
• deltaT
• distributeTermCurrent
• dynamicAnalysis
• eadVerbosityLevel
• emViolThresholdPercent
• enableDynamicRead
• enableSelfHeatingEffects
• enableViaElseRule
• forceSegmentTotal
• ictemLayerMapFile
• includeDeltaT_Margin
• lifetime
• lifetimeUnits
• metalRegionSearchExtent
• minCurrent
• odRegionSearchExtent
• preloadWaveforms
• preserveResistorCurrents
• printAdjustedCurrents
• resistorLimit
• resPathsResistorLimit
• rmsMetalLineNumAC
• rmsMetalLineNumDC
• scale
• scalingFactor
• scratchLib
• segmentLength
• sheSetupFile
• setTermNodeAsReference
• skipViaStackMetalResistor
• sumThreshold
• termPinLayersForEMCheck
• useDatasetClipInfo
• useDatasetTemperature
• useMaxRule
• viaOverlapPercentage
• warnOnEmLayer
• warnOnEmLimit
• writeEMResultsToOA
• preEMCheckLayers
• preEMDescendIntoPCell
• preEMDetailReport
• preEMLogFile
• preEMViolThresholdPercent
• minResistorCurrent

autoDatasetCustomProc

layoutEAD.em autoDatasetCustomProc string nameOfTheUserDefinedFunction

Description

Specifies the name of the user-defined function to be called for custom current distribution strategy.

Consider that you have defined a custom procedure named, autoDatasetUserFunc as follows:

(define (autoDatasetUserFunc t_dataSetName d_masterCellViewId d_instId t_deviceTermName t_termName)   aspectRatio = userFuncToComputeAspectRatio( d_InstId)   aspectRatio ; returnValue)

This user-defined function is run for each device terminal connected to the net and returns a floating-point value. The current among the device terminals is distributed in the proportion of the values returned by the user-defined function.

Consider that there are three device terminals, M0:D, M1:D, M2:S, connected to a net N0. Now, if the function returns 1, 2, 3 values for these device terminals respectively, then current is distributed in the proportion of 1/6, 2/6, 3/6, respectively, as described in the following table.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "autoDatasetCustomProc")

envSetVal( "layoutEAD.em" "autoDatasetCustomProc" 'string "autoDatasetUserFunc")

Related Topics

Generating EAD Dataset

autoDatasetDeviceLengthPropList

autoDatasetMacroProp

autoDatasetDeviceWidthPropList

autoDatasetDeviceLengthPropList

layoutEAD.em autoDatasetDeviceLengthPropList string "listOfLengthProperties"

Description

Specifies a list of length properties for a device. These properties are used to find out the device length, which is then used to calculate the aspect ratio (width/length) for the device. The aspect ratio can be used as a current distribution strategy in case of automatic dataset creation.

The default value is "l L", which indicates property l is searched first to find the device length. If the property l is not found, then property L is used.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "autoDatasetDeviceLengthPropList")

envSetVal( "layoutEAD.em" "autoDatasetDeviceLengthPropList" 'string "length Length")

Related Topics

Generating EAD Dataset

autoDatasetCustomProc

autoDatasetMacroProp

autoDatasetDeviceWidthPropList

autoDatasetMacroProp

layoutEAD.em autoDatasetMacroProp string "listOfLengthProperties"

Description

Specifies the property name that is read on a macro Pcell to find out aspect ratio of devices inside the Pcell.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "autoDatasetMacroProp")

envSetVal("layoutEAD.em" "autoDatasetMacroProp" 'string "macroCellProp")

Related Topics

Generating EAD Dataset

autoDatasetCustomProc

autoDatasetDeviceLengthPropList

autoDatasetDeviceWidthPropList

autoDatasetDeviceWidthPropList

layoutEAD.em autoDatasetDeviceWidthPropList string "listOfWidthProperties"

Description

Specifies a list of width properties for a device. These properties are used to find out the device width, which is then used to calculate the aspect ratio (width/length) for the device. The aspect ratio can be used as a current distribution strategy in case of automatic dataset creation.

The default value is "w W", which indicates property w is searched first to find the device width. If the property w is not found, then property W is used.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "autoDatasetDeviceWidthPropList")

envSetVal( "layoutEAD.em" "autoDatasetDeviceWidthPropList" 'string "width Width")

Related Topics

Generating EAD Dataset

autoDatasetCustomProc

autoDatasetDeviceLengthPropList

autoDatasetMacroProp

autoDatasetDistributionMethod

layoutEAD.em autoDatasetDistributionMethod cyclic {Aspect ratio| Equal | Custom}

Description

Specifies the current distribution method to use when generating EAD datasets.

Valid values are:

• Aspect ratio: Distributes the specified current among the devices in proportion to their aspect ratio, that is width/length. For example, if the devices M10 and M5 have aspect ratios 150 and 75, respectively, the M10 gets twice as much current as M5 does.
• Equal: Distributes the specified current equally among different device terminals connected to the net.
• Custom: Distributes the specified current among different device terminals according to the custom current distribution defined in the user-defined function specified by the environment variable autoDatasetCustomProc.

The default value is Aspect ratio.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "autoDatasetDistributionMethod")

envSetVal("layoutEAD.em" "autoDatasetDistributionMethod" 'cyclic "Equal")

envSetVal("layoutEAD.em" "autoDatasetDistributionMethod" 'cyclic "Custom")

Related Topics

Generating EAD Dataset

autoDatasetDeviceLengthPropList

autoDatasetMacroProp

autoDatasetDeviceWidthPropList

adjustedCurrentMsgRelTol

Specifies the relative tolerance limit to determine whether to print the adjusted current message if adjustment is not within the specified relative tolerance.

layoutEAD.em adjustedCurrentMsgRelTol float 0

envSetVal("layoutEAD.em" "adjustedCurrentMsgRelTol" 'float 0)

float

0

When source and sink currents for a net do not sum up to zero, EAD adjusts these current values to make them KCL compliant and displays a warning message in CIW. The warning message also prints the original and adjusted values for each terminal, if the printAdjustedCurrents environment variable is set to t.

When the number of terminals printed in the message are too high, you may want to selectively view only those terminals for which the difference between the original and adjusted currents is significantly high. Such terminals can be filtered based on a user-specified relative tolerance value.

Consider the following example, where a non-KCL compliant terminal, Ibias, is printed in the warning message:

Adjusted currents for 'Iavg (AVG)' are as follows:

Term Name        Specified Value    Adjusted Value

Ibias                         1A             0.9A

Here, the difference between the specified and adjusted current values is 0.1A (=1A-0.9A), which is 10% of the specified value 1A. If you do not want to print such terminals for which the difference between the specified and adjusted value is within 10% of the specified value, set the relative tolerance value to 0.1, as follows:

envSetVal("layoutEAD.em" "adjustedCurrentMsgRelTol" 'float 0.1)

customSHESetupFile

layoutEAD.em customSHESetupFile string "pathToCustomSHESetupFile"

Description

Specifies the path to the custom setup file that contains constant values and custom equations to be used while calculating delta-T in the custom self-heating effects (SHE) flow.

The default value is an empty string.

When using the custom SHE flow, custom equations are applied on the simDeltaT temperature that is obtained from the simulator.

To use the custom SHE flow, ensure that both the environment variables, sheSetupFile and customSheSetupFile, are defined.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "customSHESetupFile")

envSetVal("layoutEAD.em" "customSHESetupFile" 'string "/servers/user/SHE/custom.sh")

Related Topics

Viewing Delta T Information

sheSetupFile

currentDensityMPVDefault

By default, the unit for current density limit for via layers depends on the value of currentDensityMPV in the EM rules. If the EM rules contain currentDensityMPV=true, the current density unit is mA/via. If the EM rules contain currentDensityMPV=false, the current density unit is mA/um.

If currentDensityMPV is not set in the EM rules, unit to be used for current density limit depends on the value of this environment variable.

layoutEAD.em currentDensityMPVDefault boolean t

envSetVal("layoutEAD.em" "currentDensityMPVDefault" 'boolean t)

t

nil

nil

cdfPercentage

Defines the value to be used by the cdf_percentage variable for the calculation of CDF (Cumulative Distribution Factor) required for determining the maximum current limit.

For more details, refer to Rules for Defining EM Parameters in the Voltus-Fi Custom Power Integrity Solution XL User Guide.

layoutEAD.em cdfPercentage float 0.0

envSetVal("layoutEAD.em" "cdfPercentage" 'float 0.0)

0.0

computeIRDropWhenLoadingSetup

When the environment variable writeEMResultsToOA is set to t, electromigration results are saved to the OA database while saving the layout view. When you reopen the design in Virtuoso Layout EAD, the saved results are loaded and IR drop is also calculated for all resistance paths.

For designs that have nets with large number of resistors, this calculation may take time. The environment variable computeIRDropWhenLoadingSetup enables you to choose whether to calculate IR drop along resistance paths in the layout when the EAD Browser is initialized.

layoutEAD.em computeIRDropWhenLoadingSetup boolean t

envSetVal("layoutEAD.em" "computeIRDropWhenLoadingSetup" 'boolean t)

t

nil

t

checkResWidthAndEMLength

layoutEAD.em checkResWidthAndEMLength boolean {t | nil}

Description

Specifies whether to compute the width for a single-tile resistor in the orthogonal direction of the EM length or in the same direction of the EM length.

The default value is nil, which indicates that width of a single-tile resistor is computed in the orthogonal direction of the EM length.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "checkResWidthAndEMLength")

envSetVal("layoutEAD.em" "checkResWidthAndEMLength" 'boolean t)

defaultCurrent

Specifies the default terminal current to use when computing EM effects.

layoutEAD.em defaultCurrent float 0.0

envSetVal("layoutEAD.em" "defaultCurrent" 'float 0.0)

float

0.0

deltaT

Specifies in degrees Celsius the increase in junction temperature due to joule heating.

layoutEAD.em deltaT float 5

envSetVal("layoutEAD.em" "deltaT" 'float 5)

float

5

distributeTermCurrent

Produces a more accurate modeling of the terminal region, especially with wide source/drain terminals that are strapped by a row of vias. Set this variable to t if there is a suspected false EM violation in or near a terminal geometry.

layoutEAD.em distributeTermCurrent boolean t

envSetVal("layoutEAD.em" "distributeTermCurrent" 'boolean t)

t

nil

nil

dynamicAnalysis

Enables dynamic EM analysis.

layoutEAD.em dynamicAnalysis boolean nil

envSetVal("layoutEAD.em" "dynamicAnalysis" 'boolean nil)

t

nil

nil

eadVerbosityLevel

layoutEAD.em eadVerbosityLevel cyclic {low | high}

Description

Specifies whether to display multiple warning messages for each layer or a single warning message per unsupported rule for all layers.

The default value is low, which indicates that only a single warning message per unsupported layer is displayed for all the layers.

This environment variable works only if the warnOnEmLimit is set to t.

GUI Equivalent

None

Examples

envGetVal("layoutEAD.em" "eadVerbosityLevel")

envSetVal("layoutEAD.em" "eadVerbosityLevel" 'cyclic "high")

Related Topic

warnOnEmLimit

emViolThresholdPercent

Specifies the threshold value of J/Jmax ratio in percentage beyond which the EM analysis reports them as EM violations.

layoutEAD.em emViolThresholdPercent float 100.0

envSetVal("layoutEAD.em" "emViolThresholdPercent" 'float 100.0)

float

100.0

enableDynamicRead

Specifies that currents for terminals that do not have datasets are dynamically read and transferred from the schematic source before an EM check is run.

Switch on this option when working with partial layouts that have incomplete nets to ensure that currents are loaded for any new terminals added to the resistor network since the last EM check.

layoutEAD.em enableDynamicRead boolean nil

envSetVal("layoutEAD.em" "enableDynamicRead" 'boolean nil)

t

nil

nil

enableSelfHeatingEffects

Enables the self-heating flow in EAD.

layoutEAD.em enableSelfHeatingEffects boolean nil

envSetVal("layoutEAD.em" "enableSelfHeatingEffects" 'boolean nil)

t

nil

nil

enableViaElseRule

Controls how EM limits are calculated when applying a PWL-based rule if no exact match of via area is found in the EM rule file.

layoutEAD.em enableViaElseRule boolean nil

envSetVal("layoutEAD.em" "enableViaElseRule" 'boolean nil)

t

nil

nil

forceSegmentTotal

Overrides the blech length calculation methods defined in the ICT file or specified by the segmentLength variable and sets the calculation method to total. In this method, the blech length is calculated as the accumulated length of all the resistors associated with a contiguous metal geometry.

layoutEAD.em forceSegmentTotal boolean t

envSetVal("layoutEAD.em" "forceSegmentTotal" 'boolean t)

t

nil

nil

ictemLayerMapFile

Specifies the path to EM Layer Map file that contains the layer mapping information.

layoutEAD.em ictemLayerMapFile string "<path_to_the_EM_Layer_Map_file>"

envSetVal("layoutEAD.em" "ictemLayerMapFile" 'string "<path_to_the_EM_Layer_Map_file>")

string

""

includeDeltaT_Margin

Enables or disables addition of the delta-T value specified on the EAD Options form to the EM temperature while finding the temperature derating factor.

layoutEAD.em includeDeltaT_Margin boolean t

envSetVal("layoutEAD.em" "includeDeltaT_Margin" 'boolean t)

t

nil

nil

lifetime

The lifetime to be used for risk-based EM analysis. In risk-based EM analysis, MTTF (Mean Time To Failure) is first calculated using Black's equation. The calculated value is then used together with the specified lifetime to determine the probability of EM failure. Specify the units using the lifetimeUnits environment variable.

layoutEAD.em lifetime float 10

envSetVal("layoutEAD.em" "lifetime" 'float 10)

float

10

ignoreResistorLimit

Controls the comparison of the resistor count against the specified resistor limit while running EM checks.

layoutEAD.em ignoreResistorLimit boolean t

envSetVal("layoutEAD.em" "ignoreResistorLimit" 'boolean t)

t

nil

nil

lifetimeUnits

The units for the lifetime value for EM analysis.

layoutEAD.em lifetimeUnits cyclic "years"

envSetVal("layoutEAD.em" "lifetimeUnits" 'cyclic "years")

years

hours

years

metalRegionSearchExtent

Used to identify the extent of the search region around a resistor to find any other resistor that reports the maximum change in temperature (delta T) due to RMS current. To get the dimensions of the search region, EAD multiplies the value specified for this variable with the minimum pitch (minimum width + minimum spacing) for the conductor layer on which the resistor is extracted. If EAD finds any other resistor with a higher delta T value, that value is used in the computation of the final delta T for the conductor.

layoutEAD.em metalRegionSearchExtent float 15

envSetVal("layoutEAD.em" "metalRegionSearchExtent" 'float 15)

float

15

minCurrent

The minimum threshold limit for Idc and Iavg currents of the terminals and instance terminals of a net for using the net in EM calculation. If the current of all terminals and instance terminals of a net is below the threshold, then EM calculation is skipped for that net.

layoutEAD.em minCurrent float 0.0

envSetVal("layoutEAD.em" "minCurrent" 'float 0.0)

float

0

odRegionSearchExtent

Specifies the dimensions (in microns) by which the bounds of a diffusion shape needs to extended to check the overlap with the metal layer on which resistor is extracted. This variable is considered while calculating the delta T values for the conductor.

layoutEAD.em odRegionSearchExtent float 1.8

envSetVal("layoutEAD.em" "odRegionSearchExtent" 'float 1.8)

float

1.8

preloadWaveforms

Specifies whether all waveforms for dynamic EM analysis are loaded at the start, or are loaded only during the EM analysis and then unloaded again afterwards.

layoutEAD.em preloadWaveforms boolean t

envSetVal("layoutEAD.em" "preloadWaveforms" 'boolean t)

t

nil

nil

preserveResistorCurrents

Preserves intermediate currents for resistors during dynamic EM analysis so that you can plot these in a Virtuoso Visualization and Analysis XL window. The default is nil, which means that currents are not preserved. When set to t, you can view the currents through any resistor in the parasitic network by clicking the right mouse button on one of the values in either the Dynamic-Rms or Dynamic-Peak column and selecting Plot Resistor Currents. For example, you might first run an EM check without preserving currents (the default setting) and then enable this option to rerun the check on selected nets of interest.

layoutEAD.em preserveResistorCurrents boolean t

envSetVal("layoutEAD.em" "preserveResistorCurrents" 'boolean t)

t

nil

nil

printAdjustedCurrents

Enables printing of messages in CIW that inform about the current adjustments done by the solver to correct KCL non-compliance during EM checking. In case of incomplete routing, or when EM currents are entered manually, EAD adjusts the current values to make them KCL compliant and displays a warning message in the CIW, as shown below:

*WARNING* Current sources or sinks for net outp do not sum to zero (possibly due to incomplete routing). Some currents have been adjusted to present the most accurate information possible for dataset dataset_0.

In addition to this message, the original and adjusted value for each terminal are also displayed when this environment variable is set to t.

Adjusted currents for 'Iavg (AVG)' are as follows:
Term Name        Specified Value    Adjusted Value
outp               -3.24805e-11A               0A
|M18.7:G           -3.24805e-11A               0A
|M18.6:G           -3.24805e-11A               0A
|M18.5:G           -3.24805e-11A               0A
|M12.6:G            8.87067e-10A               0A

layoutEAD.em printAdjustedCurrents boolean t

envSetVal("layoutEAD.em" "printAdjustedCurrents" 'boolean t)

t

nil

t

resistorLimit

Specifies the maximum number of resistors that EM checking can handle on a particular net. If the number of resistors exceeds this value, EM checking is not run for the net.

layoutEAD.em resistorLimit int 50000

envSetVal("layoutEAD.em" "resistorLimit" 'int 50000)

int

50000

Related environment variable: ignoreResistorLimit

resPathsResistorLimit

Specifies the resistor limit up to which the resistance paths are resolved for a net while populating details in the Resistance Paths table on the R tab in EAD Browser For more details, refer to R tab.

layoutEAD.em resPathsResistorLimit int 50000

envSetVal("layoutEAD.em" "resPathsResistorLimit" 'int 50000)

int

50000

rmsMetalLineNumAC

Specifies the RMS metal line number for signal nets. You can set this value to override the default value of the metal line number taken from the header section of an ICT file.

This number is used to look up the metal line rating tables in the EM models.

layoutEAD.em rmsMetalLineNumAC int 2

envSetVal("layoutEAD.em" "rmsMetalLineNumAC" 'int 2)

int

0

rmsMetalLineNumDC

Specifies the RMS metal line number for the power or ground nets. You can set this value to override the default value of the metal line number taken from the header section of an ICT file.

This number is used to look up the metal line rating tables in the EM models.

layoutEAD.em rmsMetalLineNumDC int 2

envSetVal("layoutEAD.em" "rmsMetalLineNumDC" 'int 2)

int

0

scale

Specifies that terminal currents are to be scaled when computing EM effects. You specify the factor using the scalingFactor environment variable.

layoutEAD.em scale boolean t

envSetVal("layoutEAD.em" "scale" 'boolean t)

t

nil

t

scalingFactor

Specifies the scaling factor to be used when computing EM effects. All terminal currents are scaled by this value. This factor is considered only when the scale environment variable is set to t.

layoutEAD.em scalingFactor float 1

envSetVal("layoutEAD.em" "scalingFactor" 'float 1)

float

1

scratchLib

Specifies the library in which the scratch layout is created when performing EM analysis on power grids. See the Running EM Analysis on Power Grids section for more information.

layoutEAD.em scratchLib string "<name_of_the_scratch_library>"

envSetVal("layoutEAD.em" "scratchLib" 'string "<name_of_the_scratch_library>")

string

""

segmentLength

Specifies the default method for EM length calculation to be used when no method is specified in the ICT file. If a method is specified in the ICT file, that is used instead of the default method.

layoutEAD.em segmentLength cyclic "centerline"

envSetVal("layoutEAD.em" "segmentLength" 'cyclic "centerline")

total

centerline

perimeter