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 :
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| Illustration 1 : Memory bloc - source (180nm) |
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| Illustration 2 : Memory bloc - target (90nm) |
In order to optimize / migrate a design, the flow requires several steps :
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| 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 :
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| 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In Virtuoso IC6.1.4, the SKILL layer has been replaced by a C++ interface.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.
| Design | Size (nm) | Tool | IC613_ISR | IC614 | Improv. |
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| standard cell A | 1.5 x 3 | VLM | 50s | 12s | x4 |
| standard cell B | 9 x 3 | VYO | 25s | 5s | x5 |
| standard cell C | 12 x 3 | VYO | 25s | 5s | x5 |
| design A | 47 x 14 | VLM | 47s | 16s | x3 |
| adc_sample_hold | 100 x 68 | VLM | 1min14s | 1min9s | x1.07 |
| OP Amp | 120 x 150 | VYO | 5min22s | 5min15s | x1.02 |
| design C | 226 x 429 | VLM | 7h | 6h35 | x1.06 |
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.
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| 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