allowedWidthRange

Specifies that a particular set of width values are legal for a given layer, instead of defining a minimum and maximum width.

In some advanced node processes, there is an additional requirement for special checking at wire jogs. Specifically, either the vertical or horizontal direction width between two inside corners of a rectilinear object must be greater than or equal to the first width value in the allowedWidthRange table for the corresponding direction if there are different widths specified for different directions. If there is only one set of allowed widths (or width ranges), then either the vertical or horizontal width between the corners must be greater than or equal to the smallest width value in the width range table.

allowedWidthRange Quick Reference

Constraint Type	Layer
Value Types	`RangeArrayValue`, `OneDTblValue`
Database Types	Design, Technology
Scope	design, foundry
Category	Length and Width

Value Types

`RangeArrayValue`	Specifies a list of `RangeValue` values.
`OneDTblValue`	The table headers are index values and the table values are legal widths, in user units, for rectangles on the layer. The last value is interpreted as greater than or equal to the given width.

Optional Parameters

`length`	Specifies that the constraint does not apply to wires shorter than this length in user units. Type: `Value`
`oaSpacingDirection`	Specifies the measurement direction. Type: `StringAsIntValue` anyDirection 0 Horizontally and vertically (default) horizontalDirection 1 Horizontally only verticalDirection 2 Vertically only
`orthogonal`	Specifies that either the horizontal or vertical distance between two internal corners of a rectilinear shape must be greater than or equal to the first width value in the `allowedWidthRange` table for the corresponding direction if `allowedWidthRange` is specified for both horizontal and vertical directions. If `allowedWidthRange` is only specified for one direction, then either distance must be greater than or equal to the first width value. Type: `BoolValue`
`measurementDirection`	Specifies the direction in which the constraint is measured, regardless of whether this is the width direction or not. The default value, `measureAny`, indicates that the constraint is measured in width direction. Type: `IntValue` `0` measureAny `1` measureHorizontal `2` measureVertical
`interSpace`	Restricts the allowed spacing to integer multiples of this value. Use `withinRange` to limit this parameter to a specified range of values. Type: `IntValue`
`withinRange`	Specifies that the `interSpace` parameter applies only within this range. Type: `RangeValue`

Examples

Example 1: allowedWidthRange Using OneDTblValue

This example sets legal widths for rectangles on Metal1 to 0.10, 0.20, 0.30 and greater than or equal to 0.40 user units.

set_layer_constraint -layer Metal1 -constraint maxWidth -Value 0.4
set_layer_constraint -layer Metal1 -constraint allowedWidthRange \
  -OneDTblValue {0 0.1 1 0.2 2 0.3 3 0.4}

Illustration for allowedWidthRange Using OneDTblValue

Example 2: allowedWidthRange Using RangeArrayValue

The following example specifies that:

Either orthogonal distance between two internal corners must be greater than or equal to the smallest width in the corresponding direction.
Legal widths for vertical wires measured in user units in the horizontal direction are 0.05, 0.07, 0.12, and 0.15 user units.
Legal widths for horizontal wires measured in the vertical direction are greater than or equal to 0.10 and less than or equal to 0.15 user units.

LEF supports only exact widths in WIDTHTABLE, except for the last value, which is interpreted as "greater than or equal to" the value.

# preferred direction vertical; oaSpacingDirection=1 (horizontal)

set_constraint_parameter -name oaSpacingDirection 1
set_constraint_parameter -name orthogonal true
set_layer_constraint -layer Metal1 -constraint allowedWidthRange \
  -RangeArrayValue {0.05 0.07 0.10 0.12 0.15}

# wrong way is horizontal, oaSpacingDirection=2 (vertical)

set_constraint_parameter -name oaSpacingDirection 2
set_layer_constraint -layer Metal1 -constraint allowedWidthRange \
  -RangeArrayValue {"[0.10 0.15]"}

Illustration for allowedWidthRange Using RangeArrayValue

Virtuoso Space-based Router Constraint Reference
Product Version IC23.1, June 2023