minVoltageClearance

Specifies the minimum spacing required for wires of different voltages in the given routing layer to all cut via shapes in the adjacent cut layers above and below.

minVoltageClearance Quick Reference

Constraint Type	Layer pair
Value Types	`FltHeader1DTblValue`
Database Types	Design, Technology
Scope	design, foundry
Category	Clearance

Value Types

minVoltageClearance constraints have a FltHeader1DTblValue that consists of FltValue-Value pairs where FltValue represents the voltage and Value is the minimum clearance, in user units.

To determine the minimum clearance, the maximum voltage swing between shapes is calculated as (max(max voltage of each shape) - (min(min voltage of each shape))). This voltage is compared with the voltage values in the table to find the first value that is less than or equal to the calculated voltage swing. The corresponding minimum clearance is required.

minVoltageClearance constraints can be applied to layer purpose pairs and nets. For more information on these applications, see Voltage-Dependent Rule Support.

Examples

For Metal1 and V1 shapes in this example,

For voltage swings >= 0.0 and < 2.5, the minimum clearance is 0.1.
For voltage swings >= 2.5 and < 6.0, the minimum clearance is 0.22.
For voltage swings >= 6.0, the minimum clearance is 0.35.

For Metal2 and V1 shapes in this example,

For voltage swings >= 0.0 and < 2.5, the minimum clearance is 0.1.
For voltage swings >= 2.5 and < 6.0, the minimum clearance is 0.23.

For voltage swings >= 6.0, the minimum clearance is 0.36.

Format	Example
Tcl	set_layerpair_constraint -constraint minVoltageClearance \ -layer1 Metal1 -layer2 V1 -symmetric true -hardness hard \ -row_name voltage \ -FltHeader1DTblValue { 0.0 0.1 2.5 0.22 6.0 0.35 } \ -row_interpolation snap_down \ -row_extrapolation {snap_up snap_down} set_layerpair_constraint -constraint minVoltageClearance \ -layer1 Metal2 -layer2 V1 -symmetric true -hardness hard \ -row_name voltage \ -FltHeader1DTblValue { 0.0 0.1 2.5 0.23 6.0 0.36 } \ -row_interpolation snap_down \ -row_extrapolation {snap_up snap_down}
LEF	LAYER Metal1 PROPERTY LEF58_VOLTAGESPACING "VOLTAGESPACING TOCUT ABOVE 0.0 0.1 2.5 0.22 6.0 0.35 ;" LAYER Metal2 PROPERTY LEF58_VOLTAGESPACING "VOLTAGESPACING TOCUT BELOW 0.0 0.1 2.5 0.23 6.0 0.36 ;"
Virtuoso	spacingTables( ( minVoltageSpacing "Metal1" "V1" ( "voltage" nil nil ) ( 0.0 0.1 2.5 0.22 6.0 0.35 ) ) ( minVoltageSpacing "Metal2" "V1" ( "voltage" nil nil ) ( 0.0 0.1 2.5 0.23 6.0 0.36 ) ) );spacingTables

Format

Example

Tcl

set_layerpair_constraint -constraint minVoltageClearance \
 -layer1 Metal1 -layer2 V1 -symmetric true -hardness hard \
 -row_name voltage \
 -FltHeader1DTblValue { 0.0 0.1  2.5 0.22  6.0 0.35 } \  -row_interpolation snap_down \
 -row_extrapolation {snap_up snap_down}

set_layerpair_constraint -constraint minVoltageClearance \
 -layer1 Metal2 -layer2 V1 -symmetric true -hardness hard \
 -row_name voltage \
 -FltHeader1DTblValue { 0.0 0.1  2.5 0.23  6.0 0.36 } \  -row_interpolation snap_down \
 -row_extrapolation {snap_up snap_down}

LEF

LAYER Metal1
PROPERTY LEF58_VOLTAGESPACING
  "VOLTAGESPACING TOCUT ABOVE
   0.0 0.1
   2.5 0.22
   6.0 0.35 ;"

LAYER Metal2
PROPERTY LEF58_VOLTAGESPACING
  "VOLTAGESPACING TOCUT BELOW
   0.0 0.1
   2.5 0.23
   6.0 0.36 ;"

Virtuoso

spacingTables(
  ( minVoltageSpacing "Metal1" "V1"
   ( "voltage" nil nil )
   ( 0.0 0.1 
     2.5 0.22
     6.0 0.35
   )
  )

  ( minVoltageSpacing "Metal2" "V1"
   ( "voltage" nil nil )
   ( 0.0 0.1 
     2.5 0.23
     6.0 0.36
   )
  )
);spacingTables

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