I heard people talking about "open circuit Impedance" and "short circuit Impedance" of the power plane of a PCB. Which one of them tells us about the impedance of the planes cavity? How do we tell the IR drop from this information? Why do we use Z11 and Z22 for the impedance rather than Z21 or Z12? ------------------------------------------------------------------ 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 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