[SI-LIST] Re: 180 degree turns in high speed lines

Hi Jim,
the issue with 90 degree bends comes up pretty regularly. The basic answer 
to that is - given typical trace dimensions for high-speed digital signals 
(trace widths a few mils) the impact on signal integrity is very minimal 
unless you have a huge number of those bends in your line.

The main issue with the design yoou descibe is going to be the via 
parasitics and the mounting parasitics of your termination resistor. 
That's the place to be worried about. Via stubs, distance to the groung 
return via, resistor pad layout etc. are things to think carefully about.

Wolfgang






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[SI-LIST] 180 degree turns in high speed lines






Hello,
Has anyone had experience with high speed traces that travel in one 
direction on an inner layer of a pcb,
and then transition to the top layer termination thru a via and then 
change direction 180 degrees?

The distance traveled on the top layer is short - just a short connection 
between a termination resistor and the ic pins, but it's the turn that 
concerns me.

After all the debate through the years on 90 degree turns, I'm interested 
in your opinions.

Thanks,
Jim


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