Virtuoso Layout Migrate - 614 Enhancements

Hi, I'm Thibault Alix and I have been working with the VLM team for two years. I'm going to present what's new in Virtuoso IC6.1.4.

Cadence® Virtuoso® Layout Migrate is the physical layout migration tool within the Cadence Virtuoso custom design environment. It supports fast process and design rule migration of hard IP, custom digital designs, mixed-signal blocks, memories, and standard cell libraries.

Below is an example of a design before and after migration using the VLM tool :

Illustration 1 : Memory bloc - source (180nm)

Illustration 2 : Memory bloc - target (90nm)

In order to optimize / migrate a design, the flow requires several steps :

Illustration 3 : Migration flow

Until IC613, the VLM standalone executable (Qtrek) was called at each step and communicated with Virtuoso using IPC through a SKILL interface :

Illustration 4 : Virtuoso / Qtrek communication

Those operations were time consuming, since Virtuoso and Qtrek were waiting each others' response after each operation.

In Virtuoso IC6.1.4, the SKILL layer has been replaced by a C++ interface. Because the code is integrated to Virtuoso, IPC is no longer used, which decreases the runtime.

Here is a benchmark test done on several designs to compare 613_ISR and 614. This test has been done on the same machine, and the values displayed are an average of three runs.

Along with this modification, the GUI has been recoded in C++, using the Qt library. It has been redesigned to ease user's operations, and helps him to analyze and solve migration results using the Annotation Browser.

Illustration 5 : Annotation Browser and VLM

Over 25000 lines of SKILL code have been converted into C++. The code is now more stable, readable, debuggable, and the architecture is such that we can quickly plug new functionalities (like the Interactive DRC Fix).

Thibault Alix