External, Strong, and Weak Pin Connections

In IC6.1.x and later, External, Strong and Weak pin connections are determined by the geometry on the Pin and the associations between the Pins and the Terms, and not by Grouping (as was the case in IC 5.1.x).

A terminal (Term) represents a logical connection. A Pin represents the physical implementation of a logical connection. A terminal may have one or more Pins. A pinFig represents a specific connection point in the implementation of the Pin. Typically, pinFigs are shapes, but they can also be other geometrical objects (such as instances). In the rest of the section, we will use the term pinFigs and shapes interchangeably for simplicity.

All of the pinFigs (shapes) on the same Pin are strongly connected to one another. These shapes represent a set of low resistance connection points to the same logical terminal. The router may chose to route the connection through the strongly connected pinFigs at the router’s discretion. A typical example of strongly connected pinFigs is the shapes on either side of a power bus on the top and the bottom of a device.

A terminal may have multiple Pins. The pinFigs (shapes) that are on different Pins, which are on the same terminal are weakly connected to one another. These shapes represent a set of high resistance connection points to the same logical terminal. For example, the two ends of a poly gate of a transistor. The router may not continue a route through weakly connected pinFigs.

External Pin connections are modeled by collections of MustJoin Terms. The router must externally connect together the pinFigs that are on Pins which are on Terms in the same “MustJoin” set.