Stats

  • Locked Locked
  • Replies 1
  • Subscribers 126
  • Views 7227
  • Members are here 0
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

in noise summary report, what's the meaning of noise contribution and %

kunmingcai

Hi, when running the ac noise simulation and get the noise summary report from Results-->Print-->noise summary....

the audio band(20~20k) is of interest, and i choose to calcuate integrated noise from 20 to 20khz, including all the noise types and come up with the noise report.

i am confused by the noise contruibution and the percent param.

Because, if i sum up the total noise contribution from all the top 20 device, it is larger than the Total summarized noise. How spectral generate the Total summarized noise?? and what's the meanning of % of total??

thanks for any reply.

  • Hi Kunming

    I think you are refering to the situation as shown below. I generated the noise report using spot noise in units of V/sqrt(Hz). We can see that "Total summarized noise" is not equal to the sum of the individual noise contributions by simply summing the first 2 items. E.g.

    5.0529e-07 + 4.75146e-07 > 6.97108e-07

    This is because when the units of the individual contribution is set as V/sqrt(Hz), total summarized noise is equal to the root-mean-square (rms) of the individual noise contributions. E.g.

    a. First the sum of the sqaure of all noise contributions:
    sum_of_squares=(5.0529e-07)^2 + (4.75146e-07)^2 + ...

    b. Find the mean:
    mean=sum_of_squares/total

    c. Take the square root of the mean:
    total summarized noise = sqrt(mean)

    Percentage contribution is calculated as follows:

    100% * (5.0529e-07)^2/sum_of_squares


    Best regards
    Quek

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.