FreeLists / si-list / [SI-LIST] Re: Diff signals

[steve weir <weirsi@xxxxxxxxxx>]

1/( 1+ (d/h)^2) is the limiting case.  If you want a real cross talk 
analysis you need to model the drivers and then plug the geometry 
into a field solver.  We have the luxury of expensive tools and the 
expertise to drive them.  We do that sort of analysis all the time.

300MHz just tells you a little bit about your minimum signal 
bandwidth.  Your rise and fall times might be anything from 100ps to 
500ps depending on your drivers.  In either case your cross talk will 
be pretty much saturated at 4 inches of parallel run so 1/(1+(d/h)^2) 
won't be too far off.  Your geometry doesn't sound like something I 
would recommend first cut.  You should be able to make your life a 
whole lot easier by rearranging how you use that space.

Steve.

At 06:35 AM 2/7/2007, snsrao sns wrote:
>Hi,
>
>   Have any one worked on Crosstalk analysis for broadside coupled 
> traces. We have broadside traces routed in a dual stripline 
> configuration with spacing to adjacent ground plane being 7.9 mils. 
> The stack structure is as below.
>
>   ----------------------------- Plane (7.9)
>   +    +    +
>   -     -     -
>   ----------------------------- Plane (7.9)
>
>   The dielectric height between + and - signal layers is also 7.9 mils.
>
>   The trace width is 4 mils and if we have followed 3W rule with 
> adjacent signals. The signals are running above 300 Mhz and the 
> length is around 4 inches. The signalling topology is LVDS.
>
>   I would like to know as how to model broadside traces for 
> crosstalk analysis. Does the conventional formula DV/1+(D/H)^2 
> works? Or it requires a detailed analysis to be done using SI 
> tools. Any inputs or feedback on the same will help.
>
>
>
>
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