[SI-LIST] Re: How to properly simulate signal integrity across PCBs interconnected by Flex?
- From: "Curt McNamara" <CurtM@xxxxxxxxxxx>
- To: <jeanpierrepoulin@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 31 Aug 2007 17:36:55 -0500
The answer to shipping clocks across flex:
Don't do it if possible. Reconsider the system, perhaps distributed
clocking would work, or even clock recovery from data. If you absolutely
had to ship clock across flex, do it differentially on two layer flex.
Next best would probably be two layer flex with ground plane under clock
and really slow clock edges.
Yes, it is likely to cause problems with emissions.
Curt
Some basics on flex:
http://connectorwizard.com/reference/articles/pdfs/flex_webinar.pdf
Curt McNamara, P.E. // senior electrical engineer=20
Logic Product Development
411 Washington Ave. N. Suite 400
Minneapolis, MN 55401
T // 612.436.5178
F // 612.672.9489
www.logicpd.com=20
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of jeanpierrepoulin
Sent: Friday, August 31, 2007 3:04 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] How to properly simulate signal integrity across PCBs
interconnected by Flex?
Hello Gurus,
I am attempting to correctly design the first time a system=20
consisting of five small PCBs interconnected by short (1-5 inch) Flex=20
cable. While most signals are single ended and of moderate speed (20-
80 Mhz and with most edges controlled by the driving strength of FPGA=20
drivers), I am particularly concerned about some clock signals that I=20
need to spread to all these PCBs and wish to properly simulate...
1. Is there a flex connector vendor in particular that publishes=20
quality IBIS model the simulating software will need?
2. What simulating software do you recommend as easiest to use for=20
this type of need?
3. Do you think usage of Flex cabling in this fashion would cause =20
problems during FCC certification?
4. Any good web site / publication you've seen on the subject of=20
signal integrity across Flex cabling?
Any hint you could offer is greatly appreciated!!
Jean-Pierre Poulin
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