Shielding Group of Nets

To half-shield nets with power rails, create a group of power nets to use as shields, and a group of nets to be shielded. Then, set the crossTalkNeighborIndex group-to-group constraint to 0. For example:

# Create the net group of nets to be shielded as type 'cross_talk'
create_group -name group1 -set $selNetsSet -type cross_talk

# Create a net group for the VDD net as type 'cross_talk'
set PWR [find_net -name {VDD}]
create_group -name group2 -set $PWR -type cross_talk

# Create a constraint group for preferred neighbors
create_constraint_group -name prefer_neighbor 
set_constraint -constraint crossTalkNeighborIndex -IntValue 0 -group prefer_neighbor

# Assign the preferred neighbor constraint group to the two net groups
assign_group_group -net_group1 group1 -net_group2 group2 -group_group_spec prefer_neighbor

Related Topics

Preparing the Routing Environment