[SI-LIST] Re: Netlist or W Elements for HSpice from Cadence Allegro
- From: Vinu Arumugham <vinu@xxxxxxxxx>
- To: Nick Luther <Nick.Luther@xxxxxxxxxx>
- Date: Wed, 21 Jul 2010 09:19:12 -0700
I use spc2spc with the -rlgcmodel and -welement options in version 16.2
and it generates lossy models.
Thanks,
Vinu
Nick Luther wrote:
> Hi Mani,
>
> You stated you are looking for a W-element model of a "differential
> trace." This sounds like a 2D transmission line model problem, so I'm
> ignoring your 3D modeling tool.
>
> You stated you have a Cadence (Allegro) board file, so I assume you also
> are running Cadence SigXP. We have a SigXP to HSpice flow documented
> within Plexus. I haven't followed this flow personally but it comes
> from reliable sources. I'll summarize what we have.
>
> W-element trace models can be extracted from Cadence SigXP as follows:
> 1) Model the trace in SigXP with a dummy driver and receiver and run a
> simulation. Ensure that you choose Analyze Preferences->Simulation
> Parameters and set the Cutoff Frequency to something other than 0 to
> choose a lossy simulation (our example case is 12 GHz). The length does
> not matter as the W element model is per unit length and the trace
> length will be defined in the HSpice netlist.
>
> 2) Open a command prompt and navigate to ..\sigxp.run\case0\sim1\ or
> something similar. Look for a file called main.spc. Run the following
> command:
> [code]
> spc2spc -welement main.spc
> [end code]
>
> This will generate a file such as: MTL_1S_2R_24.rlc. Rename this to
> something more meaningful (trace_microstrip.rlc). Check this .rlc file
> for Rs and Gd which indicate it is a lossy model (driven by non-zero
> cutoff frequency selection).
>
> 3) An example instantiation of a W-element model in an HSpice netlist is
> as follows:
> [code]
> Wmy_channel chan_in_p chan_in_n 0 chan_out_p chan_out_n 0 N=2
> RLGCfile='../models/traces/trace_microstrip.rlc' L=0.01
> [end code]
>
> The above example is for a differential trace model. The length is in
> meters.
>
> Note: This process has been tried on Cadence 16.2 but didn't yield a
> lossy model. We recommend using 15.7.
>
> I've seen this done with different tool flows. With the tool set you
> have, you probably have the option of using the HSpice 2D field solver
> if you want to model your pair from scratch. Besides SigXP, we would
> likely try an Allegro->QSI->HSpice flow.
>
>
> All the best,
>
> Nick
>
> --
> Nick Luther
> Design Engineer
> Plexus Technology Group
> Ship To: 55 Jewelers Park Drive
> Mail To: PO Box 677
> Neenah, Wisconsin 54957-0677 USA
> Nick.Luther@xxxxxxxxxx
> http://www.plexus.com/
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Mani Ganesan
> Sent: Tuesday, July 20, 2010 12:26 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Netlist or W Elements for HSpice from Cadence Allegro
>
> Hello
> I have a board file and I would like to do a TDR analysis in HSpice. To
> do
> that I need to create a netlist for HSpice and I need W element (RLGC)
> of
> the trace. I cannot create that by hand. Can anyone tell me whether I
> can
> create the W element or Netlist of a specific differential trace under
> interest from the board file in Cadence? Is there an option in the tool.
>
> I have a 3d modeling tool. But the touchstone gives only S matrix I
> believe.
> How can I get the W element of the trace so that I can use it in HSpice?
>
> Thank You
> Mani Ganesan
>
>
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