Eric, When doing SSO simulations with a transmission line make sure you keep the following in mind. a) Include any internal package coupling between adjacent pins that will cause cross-talk. b) Include any cross-talk at the board level as well. c) Account for transmission line lengths and loads so that reflections are accounted for because you will be surprised how the SSO noise couples onto a quite high or low at the source and how this "glitch" gets doubled at the far end as it hits the unterminated open circuit. Thus glitches of > 500 mV can end up potentially being seen at the far end when the get > 1V. Of course this depends on the logic families you are using but this is typical for 3.3V LVTTL or LVCMOS. It can be especially bad for large BGAs that use wire bond assembly where the internal cross talk plus SSO ground bounce will add up to produce a very nice glitch. In these cases I've seen ground bounce of 300-400 mV added with cross-talk of the same order of magnitude which shows up at high as 1.2 - 1.4 at the far end when it doubles. Of course if the "quiet" signal is something like a clock or interrupt or other async signal this could cause you real problems. Steve swldstn@xxxxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Eric Hsu Sent: Monday, February 09, 2004 5:05 PM To: Si-List (E-mail) Cc: Frank Dunlap Subject: [SI-LIST] Consideration for SSO with transmission line effect Hi expert, I'm trying to quantify the amount of SSO noise which is contributed by IO buffer with signal transmission line. Is it really matter or not to = consider for different transmission line length? In case, there is an = un-terminated topology, you may get different reflection noise due to = different transmission line length, then it may also change the di/dt on = the buffer. Best Regards, Eric Hsu Interface Technologies NetLogic Microsystems, Inc. 450 National Ave. Mountain View, CA 94043 650-961-6676 x198 This e-mail contains NetLogic Microsystems, Inc. Confidential = information ------------------------------------------------------------------ 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.org 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 ------------------------------------------------------------------ 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.org 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