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Equivalence Checking Today For a Smooth Tapeout Later

Comments(2)Filed under: CONFORMALNEWSWhen do you get ready for tapeout? Two weeks before? One month before? Or are you proactive and realize that logic equivalence verification for tapeout should start as soon as the project starts?  If I had a dollar for every time a customer called with the following, I would be a rich man:  "We are taping out next week and we are having problems verifying our design with Conformal LEC".

More times than not these are setup issues that should be addressed early in the design flow. Increasingly, designers are seeing "aborts" due to ever increasingly complex optimizations in synthesis tools. Cadence has methods to reduce or eliminate aborts, however, they sometimes involve changes in synthesis methodologies such as Module-Base Data Path. Obviously this has impacts on the flow so it should be visited early in the design cycle, not just before tapeout.

So, here is my "Top Ten" list for ensuring smooth logic verification.

10) Consider early LEC tool use and debug training. We have several very good online courses at http://trainingondemand.cadence.com.
9) Request a proactive visit by your local AE before the design starts. Perhaps include him(her) in design pre-meetings or a postmortem of the previous design.
8) Start running equivalence checking along with synthesis and simulation to look for problems early on.
7) Request the "Solving Aborts" application note from your local AE.
6) Consider turning off aggressive synthesis optimizations like inverter push and boundary optimization on blocks that easily meet timing.
5) Use the latest version of Conformal LEC. More logic optimizations are supported.
4) Consider using Module-Based Data Path (MDP) flow for Synthesis.
3) Investigate non-equivalences early to see if they are synthesis bugs.
2) Isolate aborted modules and rewrite RTL to reduce complexity where possible.

And the number one way to ensure a smooth tapeout..

1) Conformal EARLY and Conformal OFTEN!


By Team FED on March 5, 2009
Agreed.  For my customers, I'm proud to say that most of them today are doing equivalency checking earlier in the process.  Even better, I'm working with some companies now on their equivalency checking before the project starts, because they care about their methodologies.  One of my customers has built a really tight LEC process, really impressive how thorough he's been in making sure he's covered every step of the way, and no holes.

By Jason Ware on March 9, 2009
The Solving Aborts application note is now available on Sourcelink.... sourcelink.cadence.com/.../Handling_Aborts_2009_H1.pdf

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