[SI-LIST] Re: TDR in HSPICE from S parameter Touchstone File -- Help Pls.
- From: Mani Ganesan <signal.integrity2@xxxxxxxxx>
- To: Stephen Zinck <szinck1@xxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Fri, 13 Aug 2010 18:19:20 -0700
Hi Stephen
I dont think there is a short in the model. Because this touchstone was
imported in PLTS and I got a good TDR plot. But now I am trying in HSPICE.
Also I am attaching here is a measured S-parameter touchstone and not a
simulated touchstone.
I am also attaching the PLTS TDR plot.
This is the netlist I have written.
** TDR of the HFSS Simulated Model **
.OPTION post probe runlvl=5
.TRAN 0.001n 20n
.PARAM zref=50.0 vlo=0.0 vhi=1.0 td=1n rt=0.05n ft=0.05n pw=20n per=50n
Psource dut_inp dut_inn 0 zo=50.0 port=1 pulse(vlo vhi td rt ft pw per)
.MODEL s_model S TSTONEFILE=Measured_Touchstone.s4p'
+ fbase=5e7 fmax=20e9
S1 inp inn outp outn 0 MNAME=s_model zo=50.0
Tp dut_inp 0 inp 0 z0=50.0 td=1n
Tn dut_inn 0 inn 0 z0=50.0 td=1n
Pterm outp outn 0 port=2
*
*
*
Pref refinp refinn 0 Z0=zref port=3 pulse(vlo vhi td rt ft pw per)
Prefterm refoutp refoutn 0 Z0=zref port=4
*
*
*
.probe tran Vincident = par('V(refinp)-V(refinn)')
.probe tran Vmeasured = par('V(dut_inp)-V(dut_inn)')
.probe tran Vreflected=par('Vmeasured-Vincident')
.probe tran
TDRz=par('2*zref*((Vincident+Vreflected)/(Vincident-Vreflected))')
.probe tran Vstraight = par('V(outp)-V(outn)')
.end
PLTS measured TDR plot is the blue colored plot in the attached image.
Can anyone please help me in this regard.
Thank You
Mani
On Fri, Aug 6, 2010 at 11:38 AM, Stephen Zinck <szinck1@xxxxxxxxxxxx> wrote:
> Hi Mani,
>
>
>
> The plot of the model appears to be shorted somehow. The short is not in
> the netlist so it must be in the actual s-parameter model.
>
>
>
> Best regards,
>
> Steve
>
>
>
> Stephen P. Zinck
>
> High-Speed Signal Integrity Consulting
>
> Interconnect Engineering Inc.
>
> P.O. Box 577
>
> South Berwick, ME 03908
>
> Phone - (207) 384-8280
>
> Email - szinck@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>
> Web - www.interconnectengineering.com
>
>
>
>
>
> *From:* Mani Ganesan [mailto:signal.integrity2@xxxxxxxxx]
> *Sent:* Friday, August 06, 2010 02:02 PM
> *To:* Stephen Zinck
> *Cc:* si-list@xxxxxxxxxxxxx
> *Subject:* Re: [SI-LIST] TDR in HSPICE from S parameter Touchstone File
>
>
>
> Hi Stephen
>
>
>
> thank you for trying it at your end, but the put what I am looking is not
> correct. I hope you should be seeing a output like one what I have attached.
>
>
>
> But it should be like the one shown in the next picture. The red colored
> line is the one measured with this touchstone, but in a different tool.
>
>
>
> please let me know what should i chnage in the netlist.
>
>
>
> Mani
>
>
>
>
>
>
>
> On Fri, Aug 6, 2010 at 8:06 AM, Stephen Zinck <szinck1@xxxxxxxxxxxx>
> wrote:
>
> Hi Mani,
>
> This differential TDR netlist worked fine for me. I don't see any
> problems...
>
> Best regards,
> Steve
>
> Stephen P. Zinck
> High-Speed Signal Integrity Consulting
> Interconnect Engineering Inc.
> P.O. Box 577
> South Berwick, ME 03908
> Phone - (207) 384-8280
> Email - szinck@xxxxxxxxxxxxxxxxxxxxxxxxxxx
> Web - www.interconnectengineering.com
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On
> Behalf Of Mani Ganesan
>
> Sent: Thursday, August 05, 2010 07:04 PM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] TDR in HSPICE from S parameter Touchstone File
>
> Hi All
> I have a small problem in doing TDR in HSPICE. I simulated my high speed
> trace in HFSS and got the s parameter touchstone file from DC to 20GHz
> incrementing at 10MHz.
>
> I am trying to do TDR anlysis in HSPICE and would like to plot it.
>
> Can anyone confirm my following netlist and please let me know my mistakes
> as the impdeance TDR output is not correct? Please see the attached TDR
> output.
>
> Please let me know where I am going wrong.
>
> .opt post probe runlvl=5
> .tran 0.005n 8n
> S1 inp inn outp outn 0 mname=s_model
> .model s_model S N=4 TSTONEFILE="touchstone_name.s4p"
> + fbase=1e7
> + fmax=20e9
>
> .param vinput = 1.0
> .param zref = 50.0
>
> P1 inp_ inn_ 0 zo=zref port=1 pulse(0v vinput 1ns 0.01ns 0.01ns)
>
> TdrP inp_ 0 inp 0 Zo=zref td=1n
> TdrN inn_ 0 inn 0 Zo=zref td=1n
>
> P2 outp outn 0 zo=zref port=2
>
> Pref refp refn 0 zo=zref port=3 pulse(0v vinput 1ns 0.01ns 0.01ns)
> PrefT refp refn 0 zo=zref port=4
>
> .probe tran V(inp) V(inn) V(outp) V(outn)
> .probe tran vincident = par('v(refp)-v(refn)')
> .probe tran vdiff = par('v(inp_)-v(inn_)')
> .probe tran vreflect = par('vdiff-vincident')
> .probe tran TDRdiff = par('2*zref*(vincident + vreflect)/(vincident -
> vreflect)')
>
> .end
>
> Thank You
> Mani
>
>
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