Virtuosity: Virtuoso-Innovus Interoperability — Making Trim Shapes Interoperable

When your cellphone easily picks up a network when you travel to another city, or when you quickly make a payment on your favorite shopping site, it’s often a routine, intuitive, and at times, an auto-pilot activity. But behind the scenes, a whole disparate yet cohesive, interoperable network comes together to make the magic happen. No surprises here - interoperability is the global key that unlocks many doors. 

Interoperability in IC Designs  

In the IC design world, the need for high-performance designs increasingly requires a mix of digital and analog content throughout a design hierarchy. In the Cadence mixed-signal solution, the Virtuoso design platform and Innovus Implementation System empower you to easily migrate your entire design from one platform to another, taking advantage of the unique features of each platform.

As mixed-signal designs call for high interoperability, ensuring that the designs work seamlessly across platforms is paramount. As a designer, one such area that requires your attention is trim shapes created manually without using the advanced wire editing functionality in the Virtuoso design platform. Before you take your design to Innovus, you must ensure Innovus would be able to read these trim shapes as intended.

Trim Shapes in Virtuoso and Innovus

The Virtuoso design platform allows you to place a trim shape between two wire line ends to help shrink the end-to-end spacing, enclosure, and minimum area. So, you can draw a long floating metal shape on the preferred layer and just place a trim shape on top of that to indicate where the original layer should be cut away during processing.

In Innovus, if trim and metal shapes are not compatible with its routing style, Innovus cannot import and read them correctly. For example, Innovus might read the long floating metal shape as two separate shapes with a gap, which is not what we really want.

Ensuring Interoperability

To make the shapes readable in Innovus, a bridge metal needs to be added, beneath the trim shape, to fill the gap between the line ends so that the original metal shape is cut into three pieces, with different connectivity associated with each piece. The trim shape remains unchanged. Here is how a Virtuoso design shape needs to be read in Innovus for interoperability. 

Rather than discovering such incompatibility late in the day, you can proactively identify the bottlenecks right within the Virtuoso design platform and make your designs Innovus ready. 

Identifying Trim and Metal Shapes

So, the first step is to identify the trim and metal shapes in your design. Use the leReportTrimmedShapesInCustomStyle() SKILL function to generate a report listing the locations where trim and metal shapes are drawn in the Virtuoso design platform routing style. While running the function, you can control arguments such as the cellview, layer, and hierarchy depth to be searched.

When you know which trim shapes are not interoperable, you can take corrective measures such as manually cutting a metal shape and adding the bridge metal or maybe deleting the trim shape altogether. 

Converting PathSegs 

For making pathSegs interoperable, the Virtuoso design platform provides an easy way - the leConvertTrimmedShapesToPRStyle() SKILL function. The function quickly converts pathSegs that are trimmed in the Virtuoso design platform routing style to the Innovus routing style. You do have the flexibility to choose the hierarchy depth and the libraries where pathSegs need to be converted.

So, while advanced wire editing in the Virtuoso design platform automatically creates the Innovus-friendly routing, the leReportTrimmedShapesInCustomStyle() and leConvertTrimmedShapesToPRStyle() SKILL functions are useful for identifying and upgrading the data edited manually.

With these SKILL functions, jump on to quickly ensure a first pass success in making your Virtuoso designs interoperable with Innovus and ride the wave of high performance with our integrated mixed-signal solution.

Related Resources

Product Manuals

Virtuoso Layout Suite SKILL Reference Virtuoso Layout Suite XL: Basic Editing 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!

Savita Thakur

About Virtuosity

Virtuosity has been our most viewed and admired blog series for a long time. The series has brought to the fore some less well-known yet very useful software and documentation improvements and has also shed light on some exciting new offerings in the Virtuoso design platform. This series broadcasts the voices of different bloggers and experts, who continue to preserve the legacy of Virtuosity and try to give new dimensions to it by covering topics across the length and breadth of the Virtuoso design platform, and a lot more.