[SI-LIST] Re: OUTPUT IMPEDANCE CALCULATION [IBIS]

Eric Bogatin mentioned a method in his book<Signal Integrity:Simplified>.
Benny Yan


On 9/19/06, Peterson, James F (EHCOE) <james.f.peterson@xxxxxxxxxxxxx>
wrote:
>
> Another method to establish the source impedance (Zs) of a driver from
> an IBIS model is in a simulation (still using Ohms law):
>
> Create a circuit with the ibis model driving a very long transmission
> line (12 inches) with a known trace impedance (Zo). Drive the line both
> high and low and observe the porch in the waveform. The porch is caused
> by the ratio of Zs and Zo. Zs can be solved by rearranging this very
> familiar equation :
>
> Vout =3D Vin * (Zo/(Zo+Zs)) ...solve for Zs, Vout is Vporch and Vin is =
> the
> total voltage swing
>
> The porch will last as long as 2x the propagation time of the T-line.
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Scott McMorrow
> Sent: Monday, September 18, 2006 4:48 PM
> To: torocar@xxxxxxxxx
> Cc: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: OUTPUT IMPEDANCE CALCULATION [IBIS]
>
> Carlos
>
> Ohms law (Z=3D V/I).  You have a V/I curve at min/typ/max device =
> corners.
>
>
> regards,
>
> 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(r) is the registered service mark of Teraspeed Consulting
> Group LLC
>
>
>
> Carlos Toro wrote:
> > Hello members of the SI list.
> > Does anyone has experience with calculating the output impedance of a=20
> > microcontroller pin given its IBIS model?.
> >
> > I don't have access to the silicon yet, just the IBIS for now. I=20
> > intend to match impedances of critical PCB traces of our design.
> >
> > Thanks in advance.
> >
> >
> >  =20
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