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resistor noise simulation by transient analysis

rfham

Hi,

I am trying to run the simple example as depicted in the attached image, taken from Cadence's "Virtuoso Spectre Transient Noise Analysis" document, page 24.
link is support.cadence.com/.../ArticleAttachmentPortal;pageName=ArticleContent&sq=005d0000005nSd1AAE_20173303123103

But, I am not able to implement the resistor (with the user defined parameter kf) as required here!
here is my setup and simulation process:
1>insert instance "res" from analogLib in schematic editor

2>change its "model name" to say "res_mod" and also made a model file (res.scs)


3>then added this model file from ADE->Setup->Model Path. The text put in this model file is:


simulator lang = spectre
model res_mod resistor rsh=1k kf=10e-13

4>set following parameters at "tran" analysis.

I am getting error of following

looks the circuit is not stable, and i searched the forum and found the same topic of following link. but i cannot find the final solution.

https://community.cadence.com/cadence_technology_forums/f/38/p/31559/1340473#1340473

could you help to check this? thanks a lot.

Parents
  • Andrew Beckett

    I'm not sure what wasn't clear from my reply to the other post you mentioned. There appears to be a numerical instability with this trivially small circuit which shouldn't happen in real-life circuits which weren't just consisting of ideal components (ideal current sources). As I mentioned, changing the sine source to a voltage source also solves the problem - and for the purposes of illustrating how the transient noise works, that would be sufficient.

    If you see the problem with a real circuit, you should contact customer support.

    Of course, it would be good if we updated the support document to have a better example that didn't have this issue...

    Regards,

    Andrew

Reply
  • Andrew Beckett

    I'm not sure what wasn't clear from my reply to the other post you mentioned. There appears to be a numerical instability with this trivially small circuit which shouldn't happen in real-life circuits which weren't just consisting of ideal components (ideal current sources). As I mentioned, changing the sine source to a voltage source also solves the problem - and for the purposes of illustrating how the transient noise works, that would be sufficient.

    If you see the problem with a real circuit, you should contact customer support.

    Of course, it would be good if we updated the support document to have a better example that didn't have this issue...

    Regards,

    Andrew

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