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how to simulate delay of a wire?

Hi all,

We know it takes time for electrical signals to travel from one end of a wire to the other. The wavefrom seen at one end of a wire should be different from the waveform seen at the other end. How can I simulate them? At first, I though I could place two pins at the two ends. Apparently, it didn't work. Do you know any ways I can achieve that?

Thank you very much!

Marc Heise over 11 years ago

Hi,
you need to look into transmission line simulations. Spectre has two elements for that, mtline and tline (spectre -h mtline/tline).
You can find a mtline element in the analogLib.
It's not trivial to setup.
For some basic testing you could create a RC-ladder network as well.

Regards,
Marc
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Andrew Beckett over 11 years ago

Or if you're creating an extracted view with QRC, you could use the out-of-context probing capability to probe the net close to two different device pins on the corresponding schematic, and it will probe the signal at the corresponding locations on the RC-extracted layout.
Regards,
Andrew.
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rickyuexu over 11 years ago

Thank you, Marc and Andrew.
Marc, with a little googling, I think the method you mentioned applies to schematic-level simulation. Is that right? I am actully trying to simulate a layout extracted view.
Andrew, I am simulating an extracted view (Calibre). Is it any way I can do that with Calibre, instead of QRC? Thanks.
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rickyuexu over 11 years ago

OK. Now I see it doesn't matter whether I use Calibre or QRC. The thing I really need to know is "out-of-context probing", right?
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Andrew Beckett over 11 years ago

Out of context probing is only supported for Cadence extraction tools (i.e. QRC). However, if you can probe the net in the extracted view, you probably can probe the two appropriate points that you want to visualize. This is probably doable in any vendor's extracted views.
Regards,
Andrew.
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rickyuexu over 11 years ago

Thank you. I understand now.
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