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PSS shooting vs. transient with nport (S-aparm) loading

Hello,

I am simulating a differential circuit with a tune-load (LC tank), where L is modeled by EMX. I am using AnalogLib/nport cell to include S-parameter behavior of the inductor in my PSS simulations. PSS is using shooting method to solve the circuit. nport cell is created by EMX tool (interpolation method="linear").

Here is the problem that I see:

for a given condition, transient and PSS-shooting results are different (output swing in PSS is wrong; doesn't lineup with current*Rp). I checked the tstab transient results of PSS simulations and I can see that tstab results correlate with transient simulation results.

I appreciate any comments.

-Masoud

Tawna over 8 years ago

Hi Masoud,

Use interp=bbspice on your nport.
The default interpolation method is interp=linear which is best for transmission lines (think DUTs with long delay) or active devices.

If your circuit signals are more sinusoidal, use harmonic balance. If they are more digital-like, then use shooting Newton pss.
If you are a Cadence customer on Maintenance, I can suggest Articles on http://support.cadence.com .

best regards,
Tawna
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mmadiseh over 8 years ago

Thanks Tawna, please point me to the articles.

-Masoud
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Tawna over 8 years ago

Hi Masoud,

Please see article (AppNote) 20416445 S-Parameter Modeling with Broadband SPICE Technology

If this doesn't answer your questions, then file a Case on http://support.cadence.com and put me in the cc list (tawna). I have a longer presentation that I can send.

best regards,
Tawna
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