Power Calculation and Average Power for large set of input combinations (in thousands)

Hi Kashif,

Cadence provide various tools that have power analysis capabilities. Your description is kind of vague but the analysis can be done whether you have 1 input or N inputs. Most tools use some kind of activity information: user set, default, or provided through an activity file. Based on that, power is computed and can view it in average form or in some tools on a time profile. Some of the tools providing analysis capabilities are Joules (power analysis tool), Genus (synthesis), Voltus (power signoff), as well as others. Please read the corresponding section in their manual for details

hope this helps,

gh-

Hello,

Thanks for your prompt response.

Now to make my question a bit clear, let's say I have 5 input sources and hence, there will be 1024 combinations (just for example's sake).

Frequency for an input combination to remain same. Hence in order to get power ratings for the all the combinations in Cadence, how do we get it?

Please note that I do not see those tools in Cadence. Are they add-on to Cadence which can be used as a 3rd party application?

Hi Kashif,

I think you are misunderstanding how power analysis works in general. You could get power for a specific state but dynamic power is a function of the transitions as well. So number of permutations per number of inputs is not relevant; what is relevant is the activity on those inputs. For example, if you have 2 inputs, a transition from 00 to 01 will produce different power than 00 to 11 or even 01 to 00 which is just the opposite. You could create separate activity files for each permutation or assert them through tool commands but this will not lead to accurate power numbers most likely since I presume you system is indeed toggling in some particular sequence

gh-

In most tools, you will have default activity for each node in some form that equates to toggles over time. Alternatively and for more accuracy, you will be able to manually enter data or use an activity file. An activity file in formats like SAIF, TCF, VCD, FSDB, etc. will show each node and how they toggle over time per simulation vectors. Most tools will allow you to specify a window of those vectors to perform the average leakage and dynamic power analysis. If you wanted to a specific state without toggling, you can manually set the toggle and state on each node per your requirements. For details on how to do that, you would have to refer to documentation of specific tool.

gh-

support.cadence.com 

will provide you access to documentation for all Cadence tools

I think the Genus Low Power User Guide has ample detail on power analysis and is good place to start. 

Alternatively, Joules is the power analysis tool and will have additional capabilities if you are curious

good luck,
gh-