Virtuoso XL Layout Editor User Guide

Using the Virtuoso Custom Placer

Table 9-5 Fixed Constraint Handling in Virtuoso XL and Virtuoso custom placer

Pin Placement Constraints

There are three methods of setting constraints on pins. You can use the Pin Placement form, the constraint manager, or the constraint manager SKILL functions.

Pin Constraints Created Using the Pin Placement Form

When creating constraints through the Pin Placement form, three categories of constraints are used:

■Alignment

■Distance

■Fixed

You can assign pins to a fixed locations or to a particular edge and optionally ordered along each edge according to your specification. You can also specify fixed spacing for a group of pins ordered and aligned to an edge. The Pin Placement form lets you apply all three types of constraints; distance, alignment and fixed on multiple pins at the same time. Once the

Apply button is pressed, the pins are automatically moved to the constraint position.

For information about using the Pin Placement form, see “Pin Placement” on page 276.

Pin Constraints Created in the Constraint Manager

The placer honors distance, alignment, grouping, symmetry, and fixed pin constraints created through the constraint manager or constraint manager SKILL functions. For information about these types of constraints and how they are supported by Virtuoso XL and the placer, see “Constraint Manager Geometric Constraints” on page 265.

When more than one type of constraint is required, each constraint must be created separately. For example, if you want to constrain pins to an edge of a bounding box with a specified pitch, an alignment and a distance constraint must be created. Pins constrained through the constraint manager are moved to their assigned positions in the layout view when the placer is run.