[SI-LIST] AW: Lower epsilon achieves lower crosstalk

  • From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
  • To: "Liu Xike" <xike.silist@xxxxxxxxx>, si-list@xxxxxxxxxxxxx
  • Date: Thu, 11 Nov 2010 09:52:41 +0100

Hello Liu,

I think you answered your question pretty well. I personally like to phrase it 
different: "lower dk increases density". Of coarse it means the same, as 
reduced s-talk allows denser routing, but from a design prospective it makes 
more sense. I start to think about materials very early in the design phase. At 
this early stage I'm not trying to reduce x-talk, I'm trying to save Layers 
(cost), and thats a matter of routing density.

BR
Gert


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Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im 
Auftrag von Liu Xike
Gesendet: Donnerstag, 11. November 2010 07:47
An: si-list@xxxxxxxxxxxxx
Betreff: [SI-LIST] Lower epsilon achieves lower crosstalk

We could achieve lower crosstalk by using dielectric with lower permittivity, 
while keeping *Z0* as a constant.


I'm new in SI, my understanding about this question is:



If we use dielectric with lower permittivity while keeping *Z0* as a constant.

We need to reduce *h *to maintain a constant *C*, because *C*= *epsilon***w* 
/*h*, and *Z0*=1/*vp*/*C*.



Since *Z0* = sqrt(*L/C*), to keep* Z0* as a constant, the stripe line need to 
adjust it's current distribution to maintain a constant *L*.



Considering the loop area decrease because *h* is reduced, the current 
distribution should be more tighter to maintain a constant *L*.



Finally the tighter current distribution on the returning pass results in the 
reduction of the cross talk.



Are these correct? I will appreciate your help



Best Regards

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  • » [SI-LIST] AW: Lower epsilon achieves lower crosstalk - Havermann, Gert