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Print Noise Summary after "ANALYSIS DURING TRAN"

msharma

Hi,

I need to simulate the noise of my circuit at specific points in time after transient analysis. For this I use the "ANALYSIS DURING TRAN", (analysis->tran->options-?output->"ANALYSIS DURING TRAN"). I specifiy a time in actimes, and specify acnames = noise. The analysis runs successfully. However, I am unable to use the "Print Noise Summary" feature. When choosing Print Noise Summary, no dialog pops up, just an empty result window.

How can I use the "Print Noise Summary" feature when running noise analysis at specific tran points?

Thanks,

Mohit

Parents
  • Hi Mohit,

    Because I see this question a lot - and there's quite a bit of confusion around the topic of "transient noise summary", I wanted to bring this up. If you have access to http://support.cadence.com please see Article 11793398.


    Note that you can't get a transient noise contribution summary. The noise contribution summary is only possible in the Spectre small signal noise analyses (AC noise, hbnoise, pnoise).

    You may have heard that you can run ac noise at every time point during transient analysis and use the transient solution vector instead of the dc operating point bias. However, this is not equivalent to the device contributions in transient noise analysis and there is no way to calculate transient noise device contributions from this data. Because noise is modulated by varying the bias, and the noise correlations between the current time point and all previous time points must be accounted for. This is feasible when the circuit behavior is periodic (pss/pnoise, hb/hbnoise) and in steady state conditions.

    => Use the noise_on and noise_off options to find out how a particular device or sub circuit affects transient noise output.

    
    Now, if you are only interested in printing the noise summary at specific times in a transient analysis, you can use the "actimes" and "acnames" option. (This is essentially what you are doing currently, I believe).

    It will give you some time-dependent noise contributions, but it is very important to understand that this does NOT give the same results as transient noise.

    Best regards,
    Tawna
Reply
  • Hi Mohit,

    Because I see this question a lot - and there's quite a bit of confusion around the topic of "transient noise summary", I wanted to bring this up. If you have access to http://support.cadence.com please see Article 11793398.


    Note that you can't get a transient noise contribution summary. The noise contribution summary is only possible in the Spectre small signal noise analyses (AC noise, hbnoise, pnoise).

    You may have heard that you can run ac noise at every time point during transient analysis and use the transient solution vector instead of the dc operating point bias. However, this is not equivalent to the device contributions in transient noise analysis and there is no way to calculate transient noise device contributions from this data. Because noise is modulated by varying the bias, and the noise correlations between the current time point and all previous time points must be accounted for. This is feasible when the circuit behavior is periodic (pss/pnoise, hb/hbnoise) and in steady state conditions.

    => Use the noise_on and noise_off options to find out how a particular device or sub circuit affects transient noise output.

    
    Now, if you are only interested in printing the noise summary at specific times in a transient analysis, you can use the "actimes" and "acnames" option. (This is essentially what you are doing currently, I believe).

    It will give you some time-dependent noise contributions, but it is very important to understand that this does NOT give the same results as transient noise.

    Best regards,
    Tawna
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