Virtuoso Video Diary: Stranded Wire – A New Sapling in Interactive Routing

In order to drive high current and to minimize routing resistivity, it is desirable to draw wide wires. But, in mature nodes, maximum width or maximum density constraints on some metal layers prevent the designers to create wide wires. Another challenge when working with designs at advanced nodes less than 22nm is that it is only possible to route with wires at minimum width. This leads to situations where the current density or the max resistivity cannot be met.

A solution to this is: Stranded Wire

What is a Stranded Wire?

To describe stranded wire in layman's language:

Stranded Wire is composed of a number of small wires bundled or wrapped together to form a larger conductor. See the figure below.

So, in interactive routing, stranded wire is an easy way to create multiple wires at the same time on same net with built-in features to control resistance and metal density. The stranded wire feature is available in Layout XL, GXL, and EAD tiers and was introduced in the IC6.1.7 and ICADV 12.3 ISR9 releases. To access the Create Stranded Wire command, choose Create – Wiring – Stranded Wire. 

A stranded wire can be created from the following starting points:

• An empty space
• An existing single pin
• An existing wire or via
• An existing width spacing pattern

You can create the following kind of structure by using the Create Stranded Wire command.

New Videos

Did you know that we retain only 10% of what we read and 95% of what we see?

Therefore, to help you understand and get started with the Stranded Wire new features easily, we bring to you some interesting and informative videos on this topic.

Stranded Wire Support in Virtuoso and Virtuoso Advanced Nodes

This video demonstrates the basic features and bindkey controls of stranded wire.

• What is a stranded wire?
• Why do we need a stranded wire in Layout?
• How to create a stranded wire in Virtuoso layout?
• What are the stranded wire bindkey controls?
• How to terminate a stranded wire?

Stranded Wire Additional Editing Features

This video demonstrates the following editing features of stranded wire.

• Inserting Vias Automatically on Pins and Overlaps
• Using the Stranded Wire Context-sensitive Menu
• Tapering in Stranded Wire
• Creating a Stranded Wire from Tieout

Stranded Wire Advanced Node Editing Features

This video demonstrates the following editing features of stranded wire for advanced nodes.

• WSP Support in Stranded Wire
• Automatic Via Insertion at Bends
• Blockage Avoidance
• Interactive Coloring in Stranded Wire

Related Resources

• Virtuoso Space-based Router User Guide

  • Working with Stranded Wires

  • Interactive Coloring for Create Stranded Wire

• Virtuoso Layout Suite SKILL Reference

  • leHiCreateStrandedWire

• Environment Variables

  • weStrandedAlignCollinearMode

  • weStrandedColorMode

  • weStrandedLadderAtTurn

  • weStrandNum

  • weStrandSpacing

 Note: For more information on Cadence circuit design products and services, visit www.cadence.com.

About Virtuoso Video Diary

Virtuoso Video Diary is an online journal that relays information about Virtuoso videos that are available in the Cadence Online Support Video Library. Hundreds of interesting videos on a wide variety of new and exciting Virtuoso features have already been created. Virtuoso Video Diary brings you direct links to these videos and other related material, on regular basis. Click Subscribe to visit the Subscription box at the top of the page in which you can submit your e-mail address to receive notifications about our latest Video Diary posts.

Happy Reading!

Parul Agarwal