Data Driven Development – Part 2
March 18, 2011 Leave a Comment
Generating SBOCV/AOCV derate tables for a cell involves calculating a derate value for a number of load/slew combinations.
In the graph below we’ve calculated the derate for 4 cells at various load/slew points. The colors are darkest approaching 1 and brighter as the derate value moves away from 1. The + symbols show the library’s load/slew points.
Besides being fast, the latest version of Amber Path FX supports saving all derate calculations and results to a database. You can now change the load/slew selection criteria and generate new derate tables in seconds. We are adding the ability to mine this data and perform variance checks to ensure your design is operating as you expect. We are just now learning how useful this information might be – not only to improve timing results but also to make optimization choices.
The other thing that these graphs show is how unsafe using a few cherry-picked load/slew points can be. That’s the methodology some have suggested in order to make generating AOCV tables more palatable with other SPICE tools.
With Amber Path FX you don’t have to make those choices up front. You can generate an SBOCV database with a large range of load/slew points (the full set from the library or based on your design rules) and then refine based on how the cells are actually used.
We’ll have a lot more to say about this at the TSMC Technology Symposium in a few weeks but if you have questions now feel free to get in touch.
