Zhenggang Could you tell us why there is no FEXT in the case of stripline? On Fri, Nov 12, 2010 at 03:25, ZHENGGANG CHENG <zhenggang.cheng@xxxxxxxxx>wrote: > Hi Liu, > Xtalk analysis is very different for microstrip and stripline cases, and it > also depends what xtalk you are talking about such as FEXT or NEXT. > > For stripline, there is no FEXT, and NEXT proportional to Cm/C. So in this > case, lower Er, to keep the same impedance, H will be decreased, so Cm/C > will be smaller. > > For microstrip case, FEXT is proportional to Cm/C-Lm/L, and NEXT is > proportional to Cm/C+Lm/L. In your case, Lm/L is becoming larger (Lm is not > changing, L is decreased due to smaller H), Cm/C may be smaller, then FEXT > will become larger due to lower Er. > > Zhenggang CHENG > > > On Wed, Nov 10, 2010 at 10:46 PM, Liu Xike <xike.silist@xxxxxxxxx> wrote: > > > 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 > > > > ------------------------------------------------------------------ > > To unsubscribe from si-list: > > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > > > or to administer your membership from a web page, go to: > > //www.freelists.org/webpage/si-list > > > > For help: > > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > > > > List technical documents are available at: > > http://www.si-list.net > > > > List archives are viewable at: > > //www.freelists.org/archives/si-list > > > > Old (prior to June 6, 2001) list archives are viewable at: > > http://www.qsl.net/wb6tpu > > > > > > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu