[SI-LIST] Re: HSPICE S-paramter questions
- From: Scott McMorrow <scott@xxxxxxxxxxxxx>
- To: ray.anderson@xxxxxxxxxx
- Date: Wed, 16 Mar 2005 12:37:40 -0500
Ray,
The other reason for using these other tools is speed. For example,
after conversion of a Xilinx differential s-parameter model to a Laplace
pole-zero model, I typically see a 20X speed up in performance when
compared to the Spice s-element simluations. If you are doing only one
simulation, then the translation time dominates. But if you are doing
multiple trace length, connector type, backplane sweeps in simulation,
then the performance advantages of the Laplace pole-zero model is
significant, with no decrease in accuracy.
scott
Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax
http://www.teraspeed.com
Teraspeed® is the registered service mark of
Teraspeed Consulting Group LLC
Ray Anderson wrote:
>Craig-
>
>The way I interpreted Ed's question, I think he was asking about
>instabilities (non-convergence, ringing, other simulation artifiacts)
>when utilizing the Hspice S element to introduce s-parameter data into a
>spice simulation.
>
>I can't comment on the latest release, but in the past I've experienced
>"non-intuitive" results using the S element.
>
>One of the reasons there seems to be a proliferation of 3rd party
>programs like Sigrity BroadBand Spice, Optimal WideBand Convert, Apsim
>SPAR, and many other similar ones from other vendors whose purpose is to
>synthesize "black-box" n-port models from s-parameters for use in spice
>(including Hspice) is to provide an alternative to the built-in
>S-element that has seemed to be problematic especially with large (many
>ported) models.
>
>-Ray
>
>Craig Clewell wrote:
>
>
>
>>Ed,
>>
>>I will assume that when you speak of and s parameter model you are talking
>>about a Touchstone file.
>>
>>If this is the case you can import the file into Excel using comma/space
>>delimiters and then plot the appropriate s parameter.
>>
>>Then, you can set up the model by itself in HSPICE and compare the 2 curves.
>>This will insure that the s parameter file is not defective. Obviously, if
>>you don't get the same result you know that your version of HSPICE is not
>>handeling the file correctly.
>>
>>If you do have a problem in your version of HSPICE a work around may be to
>>use discrete components to obtain your ouput as opposed to using the S
>>element. I will say that I know the latest version does handle the S
>>paremters correctly
>>
>>Here is some code that will measure the S11 and S21. Just reverse the input
>>and output connections to get the S22 and S12. Also, if you would like to
>>look at more than 2 lines you can repeat this code, or put it in a subcircuit
>>so that you can wire up as many lines as you wish. This is for a single
>>ended configuration. If your application is for differential let me know and
>>I can send you the code for the differential configuration if intersted.
>>Don't forget to terminate all unused lines in Zo.
>>
>>*Input node to DUT is 20, and output node to DUT is 28
>>*S11 measured from node 8, and S21 measured from node 11
>>Rout_BW 28 9 50
>>Vin_BW 5 0 AC=1
>>Rin_BW 5 20 50
>>Vout_BW 9 0 DC=6 AC=0
>>E1x 10 0 20 0 2
>>V6 10 8 AC=1
>>R8 8 0 1e9
>>E2x 11 0 28 0 2
>>R9 11 0 1e9
>>
>>Craig
>>
>>
>>
>>
>
>
>
>
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