关于ptpx报的averaged和time_based的结果

zjt412

averaged

     

time_based

上面两幅图为我用PTPX仿得功耗结果，分别为averaged和time_based的结果，请问time_based的上半部分报的是平均功耗么？如果是为什么和averaged的结果不一样，如果不一样，那是什么？？谢谢！！！！！

lvguang

I want to know which swithing activity  files do you use, the VCD or SAIF? I think it should be VCD otherwise you couldn't get the time_based power. You should know that, SAIF is only used to calculate the average power consumption while the VCD file contains detailed signal transition information which can be used to do both the average and time-based power analysis. VCD file is a superset of SAIF file.

Assume you used the VCD file. When calculating the averaged power, only the toggle rates and time information like how  much time a signal keeps high, low, or "x" are used. When calculating the time-based power, the detailed information of the switching activities are recorded. The time-based analysis will also report the average power. Because the avaraged power analysis and time-based analysis use different models to calcluate to power, the reported power consumption usually differs.

For example, the averaged power analysis (PTPX) will only use SP1, which represents the percentage of a signal at "1" during the whole simulation time. If SP1=70%, it means this signal is high in 70% of the simlation time.  The toggle rate of some unannoated nets or cells will be derived using some specific rules. For time-based power analysis, more complicated information is used. It also calcluate the power of some specific states, like "X", "Z", using some models.

Totally speaking, they use different models to calcluate the averaged power. I don't know the accurate algorithms. But this is very normal and you don't need to be worried about this issue. If you want to know the reason, you should read the mannul.

fangwang85

回复 2# lvguang


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