maxDiffDensity

Specifies the maximum density difference between adjacent, non-overlapping density check windows.

maxDiffDensity Quick Reference

Constraint Type	Layer
Value Types	Flt1DTblValue
Database Types	Design, Technology
Scope	design, foundry
Category	Density

Value Type

maxDiffDensity constraints have a Flt1DTblValue. The lookup key (“step”) represents the step size and the value represents the maximum density difference percentage from 0 to 1, between adjacent, non-overlapping check windows. Check windows are square with equal height and width.

• If windowStepSize is not given, the check window dimensions are 2*step size.
• If windowStepSize is given, the window size that corresponds with the given step size is used.

Density checking starts with the check window in a corner of the design, then the check window is moved across the design incrementally, by step size, and the density is checked at each step.

Parameter

• windowStepSize (OneDTblValue, optional) The lookup key (“step”) represents the step size and the value represents the window size. This table is used to look up the window size associated with a given step size. When this parameter is not given, window size is equal to 2*step size.
  
  

Examples

• 1D Table: Index step size
  Sets the maximum density difference percentage for Metal2 based on the step size of the check window.
  

  Format	Example
  Tcl	set_constraint_parameter -name windowStepSize -row_name window \ -OneDTblValue { 60 120 120 240} -row_interpolation snap_down \ -row_extrapolation {snap_up snap_down} set_layer_constraint -constraint maxDiffDensity -layer Metal2 \ -Flt1DTblValue {60 0.1 120 0.2} -row_interpolation snap_down \ -row_extrapolation {snap_up snap_down} -row_name step
  Virtuoso	spacingTables( ( maxDiffDensity "Metal2" (( "step" nil nil "window" nil nil)) ( ( 60.0 120.0 ) 0.1 (120.0 240.0 } 0.2 ) ) ) ;spacingTables

Related Topics

Density Constraints

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