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AR# 62437

2014.3 Vivado Power - Does 'set_switching_activity -signal_rate' impact the glitch power analysis?

Description

Does 'set_switching_activity -signal_rate' impact the glitch power analysis?

Solution

Yes, the signal_rate option impacts the glitch analysis. 

------- Probability Equation------

 In ideal conditions, the toggle rate on an RTL node should meet this criterion:     


(RTL_toggle_rate/200) =< static_probability =< 1-(RTL_toggle_rate/200)


If the given switching rate does not satisfy this equation, then it is treated as glitch data.

 

You can extract RTL toggle rate using the following:  

2*static_prob*(1-static_prob)


For example: 

For freq 100MHz

set_switching_activity -static_probability 0.7 -signal_rate 150 [get_ports d]

Given Toggle Rate = 150/100 = 1.5  = 150%      - this given toggle Rate violates the above equation: 0.75  <= 0.7  <= 0.25


We need to extract the glitch component:

RTL Toggle Rate = 2*0.7(1-0.7) = 0.42   -> 42%

Therefore Glitch rate = 1.5 0.42 = 1.08


Once the glitch rate is identified, the glitch power analysis would be included in the general power analysis.


AR# 62437
Date Created 10/09/2014
Last Updated 10/14/2014
Status Active
Type General Article
Tools
  • Vivado Design Suite - 2014.3
  • Vivado Design Suite - 2014.2
  • Vivado Design Suite - 2014.1