[SI-LIST] Re: Via model
- From: Dorin <dorin.oprea@xxxxxxxxxxx>
- To: Istvan NOVAK <istvan.novak@xxxxxxxxxxxxxxxx>
- Date: Thu, 27 Nov 2003 10:33:38 -0500
Thanks for your feedback; this model is quite ingenious.
The problem I face with my particular circuit when using very short TL
(<10ps) is that hspice complains about dc convergence failure.
Do you have any particular option I can try?
gmindc is asking for is 0.1 which I think is too big ....
Cheers,
Dorin
Istvan NOVAK wrote:
> Dorin,
>
> Both the PI and T equivalent circuits of vias are just approximations,
> therefore they should be used only in cases when the signal edge
> passing through the model is significantly longer than the delay of the
> model, which is sqrt(L*C); in that case the two models should give
> very closely the same waveforms.
>
> If your application calls for fast
> edges, where this condition cannot be met, a more detailed via
> model is needed. In the most generic case, where you have 1...N
> metal layers in the PCB, and the trace transitions from layer A to
> layer B, you may need a PI circuit formed of three transmission lines.
> All three transmission lines can be low loss or loss less. Two
> open-ended transmission lines replace the capacitors in your present
> PI circuit, and the third line connects the two shunt lines and replaces
> L in your PI circuit. By adjusting the Zo and tpd values of all three
> transmission lines independently, you can capture the via stub
> resonances separately on top and bottom, include pad capacitances,
> as well as the delay and capacitive or inductive nature of the portion
> of the via barrel between layers X and Y.
>
> Regards,
>
> Istvan Novak
> SUN Microsystems
>
> ----- Original Message -----
> From: "Dorin" <dorin.oprea@xxxxxxxxxxx>
> To: "si-list" <si-list@xxxxxxxxxxxxx>
> Sent: Thursday, November 27, 2003 9:06 AM
> Subject: [SI-LIST] Via model
>
> > Hi,
> > What should be the model for the via:
> > a) C/2 to gnd - L - C/2 to gnd or
> > b) L/2 - C to gnd - L/2
> > The circuit I simulate shows a significant difference between the two
> > cases.
> >
> > Thanks,
> > Dorin
> >
> >
> >
> >
> > -- Binary/unsupported file stripped by Ecartis --
> > -- Type: text/x-vcard
> > -- File: dorin.oprea.vcf
> > -- Desc: Card for Dorin
> >
> >
> > ------------------------------------------------------------------
> > To unsubscribe from si-list:
> > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
> >
> > or to administer your membership from a web page, go to:
> > //www.freelists.org/webpage/si-list
> >
> > For help:
> > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
> >
> > List technical documents are available at:
> > http://www.si-list.org
> >
> > List archives are viewable at:
> > //www.freelists.org/archives/si-list
> > or at our remote archives:
> > http://groups.yahoo.com/group/si-list/messages
> > Old (prior to June 6, 2001) list archives are viewable at:
> > http://www.qsl.net/wb6tpu
> >
> >
-- Binary/unsupported file stripped by Ecartis --
-- Type: text/x-vcard
-- File: dorin.oprea.vcf
-- Desc: Card for Dorin
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
