Hi, All SI Experts: For the stripline layout, it comes to my concern for the placement of a via between two differential-pair signals routed through the via as the follows: Y-axis | | 0-----> X-axis / / Z Signal on Layer#3 / / / / / (@) / / P1 N1 | P2 N2 / / | / / (O) (O) | (O) (O) <----- Upper Layer #5 | | | | | | | | | | | | | | | (O) (O) | (O) (O) <----- Lower Layer #7 / / | / / P1 N1 (@) P2 N2 / / / / / / / / / / / / Layer / / / / #9 / / / / / / S D S where Traces P and N: a pair of differential signal routed through the via (O)-(O) S: spacing between the intra-pair (P1-N1) D: spacing between the inter-pair (N1-P2) (@)-(@): the via to be placed through the Layer #3 to the Layer #9 carrying a different power signal That is, a power signal through the via (@)-(@) from the Layer #3 to Layer #9; nonetheless, there exist two differential-pair signals routed on Layers #5 and #7. In the Z-X plane on the upper layer, one would have the top view: 0----> X | | Z | | | | P1 N1 P2 N2 | | | | | | (@) | | | | | | (O) (x) (O) (O) To minimize the electromagnetic coupling effects, what would be the required spacing between the via (x) and via (@)? Geometrically, the radius R can be referred to the distance measured from (x) to (@), where the via to be placed. What would be the recommended R for the confident signal integrity? Appreciate so much for all your comments, SI_Tek _________________________________________________________________ Add photos to your messages with MSN 8. Get 2 months FREE*. http://join.msn.com/?page=features/featuredemail ------------------------------------------------------------------ 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 archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu