Re: [SI-LIST] : Clock tree

Scott McMorrow (scottmc@teleport.com)
Thu, 06 Aug 1998 12:29:37 -0700

Shimon,

Close in the signal integrity world is one fifth to one sixth
of the fastest signal rise and/or fall time. If the distance
from the loads to the T junction is less than this, then there will
generally be minimal effect due to reflections.

However, the clock receiver input capacitance and package
parasitics also factor into the analysis. At high edge rates,
the package and die capacitance can be a significant factor.
Don't try to route clock trees without prior simulation, especially
to dissimilar receivers. You may end up with a rude surprise, otherwise,
in production.

Regards,

Scott

Shimon_Turgeman@amat.com wrote:

> is any one build clock tree on large board.
>
> what is the best way to build the clock tree ?
> I connect the same clock to few consumers which are very close ? is that
> O.K ? what is consider as "close" ?
> what is the best termination and connection for that ?
>
> Best regards
> Shimon Turgeman
> ISRAEL

--
___________________________
Scott McMorrow
Principal Engineer
SiQual

mailto:scottmc@siqual.com ___________________________