Virtuosity: Usability Enhancements in Simulation Driven Routing

We live in a world where the idea of usability is to make products easy to use, make things easily accessible, and visually appealing. It's our constant endeavor to improve the usability of our products. Watch out this space for our posts every month on usability enhancements in Virtuoso® Layout Suite.

In today’s world as technology is advancing, it has become important to drive optimal routing widths in layout implementation while maintaining EM compliance.

Simulation Driven Routing (SDR) has its own toolbar to assist layout designers seek current and resistance coverages in a design. Layout designers can use the SDR toolbar icons to speed-up the design time and route nets. You can then easily discover which nets have exceeded their current budgets and which nets have exceeded their maximum resistance parameters.

If you are interested to know the basics about SDR, check out our blog on Introduction to Simulation Driven Routing.

Usability Enhancements in SDR

Since IC6.1.8 and ICADVM18.1 was released, we have continued our drive to improve the usability of SDR. Read through this blog to know about the key enhancements made in this area.

Sources and Sinks Map

Display of sources and sinks map now provides two levels of granularity. A drop-down button has been added next to the Sources and Sinks Map button on the SDR toolbar to let you choose between clusters or instance pins.

• The cluster view provides you with a high-level perspective of the current distribution across the pin cluster on a thermal map.
• The pin view provides a precise view of the current distribution on each pin.

These views let us see the difference between how the thermal map shows the current distribution across pin clusters and on a single pin.

Different Methods of Generating Current Datasets

The different methods of generating current datasets help you quickly start with SDR.

• Using Virtuoso ADE Assembler
• Using a CSV File
• Using the EAD Browser
• Using High Current Design Intent (New)

For using the Design Intent (DI) high current in SDR, we have integrated Virtuoso Design Intent and SDR together for an easy and fast solution to define currents and electro-migration results. In SDR, this helps us understand how big should the metal layer be to carry current. A new button, Import DI as Dataset, on the SDR toolbar lets you create or update the EAD dataset with the design intent information.

For more information, check out the application note on this enhancement.

Width Multiplier

It is now easier to calculate the value of wire width that is to be applied to the trunks and twigs. The Scaling Factor field on the SDR toolbar has been renamed to Width Multiplier and the use model has been simplified. The value of the width multiplier is no longer a percentage but a float value. The estimated value, based on the current, is now multiplied by the width multiplier value specified in the field and then the calculated wire width is applied.

Twig Stacking

SDR allows stacking of twigs on different metal layers until they can carry the required amount of current. 

To avoid DRC errors, the twigs in SDR cannot be bigger than the pin width. So, if the width of a twig is not large enough to carry the current, then we can stack the twigs on consecutive layers, for example, M2/M3/M4. You can control the layer stack by using the bindkeys. Use the = bindkey to move up the twig stack layers and - bindkey to move down the twig stack layers.

Over-Device Routing

In the FinFET technology, the routing density is the most important criteria. Devices (especially MOS) have a different structure than before and are less sensitive to the over-device routes. Therefore, simulation-driven interactive routing now supports over-device routing, which is automatically enabled when the trunk is over the device pins. 

Note: The over-device route is supported for Create Wire and Create Stranded Wire commands.

Related Resources

User Guide

Virtuoso Simulation Driven Interactive Routing User Guide

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

Contact Us

For any questions, general feedback, or even if you want to suggest a future blog topic, write to custom_ic_blogs@cadence.com.

Happy reading, and stay safe!

Parul Agarwal

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