[SI-LIST] Re: matching within 1 mil
- From: "Kihong Kim" <joshuakh@xxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 1 Jun 2007 11:43:27 -0400
I agree on Jeff's view quite happily.
This is about the optimization among physical constraints including cost.
Signal integrity is not pursuing THE best signal quality.
I think it should pursue most optimal signal quality under the imposed
constraints.
Kihong Joshua Kim
SI in Photonics and Electronics
>
>
> On 6/1/07, Loyer, Jeff <jeff.loyer@xxxxxxxxx > wrote:
> >
> > I think folks are missing Bill's point. I don't think he's saying that
> > the design is going to break at 2 mils routing difference, only that he
> > can easily attain a maximum 1 mil delta, so he uses that as his
> > constraint. If his CAD folks balked at that number, he'd probably
> > adjust accordingly and, if it got close to having significant impact,
> > would do a more detailed analysis.
> >
> > This is very similar to what we've done for common-clock FSB signals:
> > tell our CAD folks to match them within 10 mils (or some number), even
> > though we know we can absorb more. But, 10 mils is easily attainable,
> > and guarantees essentially no skew due to length differences. Granted,
> > it's a little more work on CAD's part, but the tradeoff is I don't have
> > to do a grand analysis to figure out exactly how close they HAVE to be
> > matched, and then worry about whether my analysis was correct (and
> > require subsequent validation in the lab, etc.).=20
> >
> > This is about compromises, and where you put your energy into in-depth
> > analysis. If you can easily do 1 mil spacing, no problem. It's a
> > little tighter than I'd generally specify, but it's not absurd, either.
> > If you're using an auto-router (that's surprising to me, I didn't think
> > leading-edge designs could use them), you probably have different
> > constraints.
> >
> > Jeff Loyer
> > ------------------------------------------------------------------
> > 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.net
> >
> > 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
> >
> >
> >
>
------------------------------------------------------------------
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.net
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:
