FreeLists / si-list / [SI-LIST] Re: Interconnect Lumped Modelling

["Dima Smolyansky" <Dima.Smolyansky@xxxxxxxxxxxxxx>]

Strad,

This analysis comes to us, I believe, from the basic physics of matter -
more specifically, from the wave-particle duality of matter. There, an
object is considered a wave or a particle depending on its size compared to
the given wavelength. Lambda /10, specifically, is the rule there, where
Lambda is the wavelength, and this is why the most rigorous rule people
apply is Tr>Td/10.

Specifically to your question: before the edge reached 90% of its value, the
interconnect length should be traversed several times - about 10 times, if
you apply the rule above directly. Most practical designers I talked to are
content with smaller factors ( 2.5-4 is a typical ratio designers use), so
that is how many times the interconnect length is traversed.

For a faster rise time, the length of the interconnect that is considered
lumped must decrease - for a large rise time, it will increase.

Thanks,

===================
Dima Smolyansky
TDA Systems, Inc.
4000 Kruse Way Place
Bldg. 2, Suite 300
Lake Oswego, OR 97035
(503) 246-2272
(503) 246-2282 (fax)
www.tdasystems.com


----- Original Message ----- 
From: "Stradlin Donald" <stradlin_03@xxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Tuesday, August 05, 2003 11:56 AM
Subject: [SI-LIST] Interconnect Lumped Modelling


> Hi All:
>
> I was just have a problem comprehend a certain theory practially and
physically. Many theories suggest that a via/transmission line can be
modelled as a lumped element if Tr>>Td where Tr = rise time of the pulse and
Td = propagation delay of the length of via/transmission line.
>
> What  might be the physical implications of this comparison ? Does it mean
that before the edge reached 90% of it final value, the interconnect length
should be traversed ?
>
> Is it a faster rise time or a larger rise time ?
>
> -Strad.
>
>
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