Stats

  • Locked Locked
  • Replies 2
  • Subscribers 125
  • Views 14270
  • 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

Unable to use rmsNoise function

Deepansh

Hello,

I am using virtuoso 6.1.3 to design a low noise operational amplifier. I used the PSS+Pnoise analysis in ADE to plot the input referred noise of my op-amp.However, when using the rmsNoise function in the Visualization and Analysis  L Calculator , I am getting the following message in the CDS log:

"rmsNoise(10 20k )"
*Error* rms Noise data not available
Expression evaluation failed: Expression evaluates to nil
Expression evaluation failed: Expression evaluates to nil
nil

I suspect I might not be using the function in the right way.Can someone please guide me on how to use this function?Do I have to do something apart from what was mentioned in the Waveform Calculator Guide?

Thank You 

  • The rmsNoise function only works using the result of the noise analysis (not pnoise). You'd need to do thiss:

    sqrt(integ(getData("out" ?result "pnoise")**2 10 20k))

    Essentially rmsNoise is doing something similar, but effectively with ?result "noise" rather than ?result "pnoise". You'll see this is integrating the square of the output noise (which is in V/sqrt(Hz)) over a frequency range of 10 to 20kHz, and then taking the square root of the result.

    Regards,

    Andrew.

  • Hey Andrew,thanks for replying to my post.I indeed did try the code which you provided, and it works fine.Thank you for your help!

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.