FreeLists / si-list / [SI-LIST] Differential Impedance of PCB Vias

[Hirshtal Itzhak <ihirshtal@xxxxxxxxxx>]

Hello,

I need to route a 3.125Gb/s 100-ohm diff pair such that it traverses
from one layer of a PCB to another layer through a pair of vias about
100mil long.

I would like to keep the diff impedance of the pair of vias as close to
100-ohm as possible.

How can I estimate the diff impedance of the vias? Is there a reliable
formula to calculate this value out of the self characteristic impedance
of the vias or from their geometrical dimensions?

Thanks for anyone who can contribute

Itzhak Hirshtal
Elta Electronics
Israel



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