Ibrahim, I have tried to answer your question below. Others, While on this subject, when running SSO simulations should one include the board models. What I am working on is using a 3D and 2D modeler to extract my package parasitics and board parasitics. Will the package parasitics suffice since SSO noise is basically on the chip or do I need the board parasitics too to run my simulations? Also, the ristimes of my fastest signals are around 70 ps, do I need to use the Ansoft HFSS or can I do with the Ansoft SI3D as my 3D modeler. Thanks, Khalid Hello Gurus, Does the concept of Simultaneous Switching (SSO) apply only to single-ended signal or the differential pairs as well. --It applies to both, of course differential signaling has better results in the presense of SSO. SSO, which is basically due to ground bounce is effected by the package and socket inductance. In other words, do we only care (when designing the decoupling strategy) how many single-ended outputs are switching simultaneously or do we have to account for diff. pairs as well. --both, when you design for decoupling you also care about the transient current requirement. There were quite a few good emails going back and forth on the subject of decoupling just a week back on the reflector. Khalid ------------------------------------------------------------------ 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