[SI-LIST] Re: hspice simulation with w-element + s model
- From: Alan Hilton-Nickel <Alan.Hiltonnickel@xxxxxxx>
- To: haikun@xxxxxxxxx
- Date: Mon, 06 Mar 2006 12:50:26 -0800
Haikun,
I haven't got any experience with S-models (although I know
it's coming), but from a quick look at the HSPICE SI Guide
(at /import/datools5/vendor/hspice/h2004.03/docs) it seems
the w-element and s-element are mutually exclusive ways of
describing a physical line.
I think the following line:
* The differential pair
w1 in1 in2 gnd out1 out2 gnd smodel=s_model N=2 l=2cm
+ NODEMAP=I1I2O1O2
should be
* The differential pair
s1 in1 in2 gnd out1 out2 gnd smodel=s_model N=2 l=2cm
+ NODEMAP=I1I2O1O2
Also, since you are modeling 4 ports, shouldn't N=4?
Alan
Haikun Zhu wrote On 03/06/06 12:12,:
> Hi there,
>
> Thanks for everyone helped me out about the embedded microstrip line
> impedance. Now I got this new question of w-element + s model
> simulation in hspice.
>
> I'm trying to produce the eye diagram for a differential microstrip
> line. The line ports are numbered like this:
>
> 1 + ------------------------ + 3
> 2 + ------------------------ + 4
>
> I exported the 4-port touchstone file from ADS and throw it into
> hspice. Here is part of my netlist
>
> *************** netlist snippet start ********************
> * Termination
> rout1 out1 gnd 22.6
> rout2 out2 gnd 22.6
>
> * Input PRBS
> vin1 in1 gnd LFSR (0 1 100ps 6.67ps 6.67ps 15G 85 [7,1] rout=3D22)
> vin2 in2 gnd LFSR (0 -1 100ps 6.67ps 6.67ps 15G 85 [7,1] rout=3D22)
>
> * The differential pair
> w1 in1 in2 gnd out1 out2 gnd smodel=3Ds_model N=3D2 l=3D2cm
> + NODEMAP=3DI1I2O1O2
>
> * s model
> .model s_model S TSTONEFILE=3D'mydiffpair.s4p' XLINELENGTH=3D2cm
> ************* netlist snippet end ****************
>
> Now i constantly get the error message
> **error** (S model: (0:s_model) ) near and far end of the line 0 are
> not connected. please check the s-parameters and NODEMAP at 0 Hz
>
> It looks to me that it's the problem of node mapping. However, i tried
> different mapping orders and still can not get rid of the problem. I
> had no problem for single-ended case, no problem for s-element +
> touchstone file for this differential pair.
>
> Thanks in advance!
>
> Haikun
> Graduate student
> UCSD
>
> --
> For every difficult problem there is always
> a simple answer and most of them are wrong.
> -- Clayton R. Paul
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--
Alan Hilton-Nickel
Signal Integrity Engineer
Sun Microsystems Inc.
Netra Systems and Networking
Newark, CA
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