pci trace impedance

["Hofmans, Kim" <kim.hofmans@barco.com>]

Hi,

the PCI spec 2.1 proposes that the unloaded characteristic impedance of the
shared PCI signal traces on the expansion card should be within 60-100 Ohm
range.
Does anyone ever experienced problems with 50 Ohm signal traces ?

I'm asking this because we're designing a board where the inner traces have
a 50 Ohm impedance and the outer traces
a 75 Ohm impedance. Since it's impossible for us to route all the PCI traces
on the outer layer(we're using a BGA), some of the traces will have to be
routed through the inner layer.

Thanks in advance !

wkr,

Kim

-------------------------------------------------------------------------
Kim Hofmans   	           	kim.hofmans@barco.com
R&D Engineer               	Barco Graphics
tel : +32-(0)9/21 69 342	Tramstraat 69
fax: +32-(0)9/21 69 825	B9052 Gent-Belgium
 
big brown rabbits often yield great big 
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