lxAllowPseudoParallelNets

layoutXL lxAllowPseudoParallelNets boolean { t | nil }

Description

Automatically identifies nodes that qualify as pseudoparallel connections and defines them during chaining and abutment. A pseudoparallel net connects nodes that are always the same voltage, so the current does not pass through the net. Contacts are dropped automatically, if appropriate. However, if preserveTerminalContacts is switched on, the contacts are preserved.

The default is nil.

This environment variable applies only when chaining is turned on. It does not control the automatic identification and creation of pseudoparallel nets during manual abutment. To do that, use the setPPConn environment variable.

GUI Equivalent

Command:	Options – Connectivity (Generation tab)
Field:	Create interdigitated chains (Connectivity Form)
Command:	Connectivity – Generate Selected Components
Field:	Interdigitate Chains (Generate Selected Components Form)

Examples

envGetVal("layoutXL" "lxAllowPseudoParallelNets")

envSetVal("layoutXL" "lxAllowPseudoParallelNets" 'boolean t)

envSetVal("layoutXL" "lxAllowPseudoParallelNets" 'boolean nil)

Additional Information

To see the significance of pseudoparallel nets, consider a symmetric series of N-transistors, A and B, tied in a series pull-down chain to ground, as shown in the following figure. Both A and B are folded into two legs, with A1, net_PP, and B1 connected in series to ground, and likewise A2 and B2 connected in series to ground, with both pairs in parallel. The nodes between A1 and B1 and between A2 and B2 are electrically equivalent. In reality, no current passes through that connection and it need not physically be made.

For more information, see Pseudoparallel Connections.

Virtuoso Layout Suite XL: Connectivity Driven Editing User Guide
Product Version IC23.1, November 2023