Virtuoso XL Layout Editor User Guide

Wire Editing in the Virtuoso XL Layout Editor

2.Choose Options – Route.

The Route Options form appears.

3.Turn Allow Floating Nets on.

4.Digitize points where you want to route the path.

If the current layer is not a valid routing layer, the first designated routing layer in the technology file or rules file will become the routing layer.

When creating a floating path, the net name appears in the status banner assp_net with a unique net number appended. Once the floating net is completed, it is assigned a net ID composed of a le_ex prefix with a unique net number appended.

Connecting Multiple Component Pins

Multiple Component Connection lets you connect multiple component pins (terminals of components) or top level component pins (instance pins) to the same net.

Connects components creating separate path segments.

Use the Create Path command to connect multiple same net component pins that are in alignment by clicking on the two outermost pins. The resulting path contains connections to each pin and separate path segments between each adjacent pair of pins.

Note: If the pins are not in alignment, a single path is created with connections only to the pins that are clicked on. Shape pins (top-level shapes that are also pins) are considered io_ports and will not be connected using the Multiple Component Connection option.

For more information, refer to “Pins” in theVirtuoso Custom Placement and Routing Preparation Guide.

Virtuoso XL Layout Editor User Guide

Wire Editing in the Virtuoso XL Layout Editor

Pushing Routes and Components

Push Routing

Push Routing controls whether paths and vias are pushed aside while routing to maintain current clearance rules. By default Push Routing is on.

To control pushing of routes, do the following:

1.From the layout window, choose Options – Route.

The Route Options form appears.

2.Turn Push Routing off or on.

Note: When Push Routing is on, use Allowing Orthogonal Jogs to control whether orthogonal jogs are allowed in the nets you are pushing.

Pushing Components

Push Component controls whether components are pushed aside while routing if there is insufficient space to route the path.

To control pushing of components, do the following:

1.From the layout window, choose Options – Route.

The Route Options form appears.

2.Turn Push Component off or on.

Components are pushed aside only if there is insufficient routing space. If there is sufficient routing area for the paths you are routing, the paths will be routed around the component, rather than push the component.

Routing Shielded Nets

The Auto Shield option automatically routes shield wires around nets that have a shield rule attached to the net.

To route shielded nets, follow these steps:

1.Create a .do file using the circuit and rule commands to assign shielding rules to the net.

Virtuoso XL Layout Editor User Guide

Wire Editing in the Virtuoso XL Layout Editor

Choose the type of shield (parallel, tandem or coax), specify the net to be used as a shield, and assign the overhang, width and gap rules you want to apply. For example:

circuit net NET5 (shield on (type parallel) (use_net GND)) rule net NET5 (tandem_shield_overhang 1.5)

rule net NET5 (shield_width 1) rule net NET5 (shield_gap 1.5)

For more information about shielding rules, refer to shield_descriptor in the IC Shape-

Based Placer/Router Documentation.

2.Load the .do file.

For more information about loading .do files, refer to,“Loading .do Files” on page 417.

3.From the Route Options form, turn Auto Shield on.

4.From the layout window, choose Create – Path.

5.Click or area select a connectivity object (pin, via, or an existing path) of the net you want to shield.

6.Digitize points where you want to route the path.

7.Finish the path by doing one of the following:

From the Layout pop-up menu, choose Finish Routing.

The connection will be finished from the last digitized point. An area for the path must lie within the routing search area or the automatic operation is terminated. Some connections may require layer changes and vias to be added in order to finish the connection.

Double click or press the Return key.

The selected net is automatically routed with a shield.

The shield command requires sufficient clearance around the wires to be shielded.

Wherever there is insufficient space, the command leaves a gap in the shield wire.

8.Tie down the shielding net to the source.

The shielding net is left floating and must to be manually connected to the source.

Routing Tandem Layer Pairs

To route tandem layer pairs, follow these steps,

1. From the layout window, choose Create – Path.