Timothy, If're you using the part where you're varying Ccomp as the driver, AND your net is ideally terminated, then that's exactly what you're supposed to see - no difference. The V-T curves are produced with Ccomp "included", so the IBIS simulator is supposed to adjust the driver's behavior so that the V-T curves are reproduced, irrespective (within limits) of the value of Ccomp. I did some investigations on this a while back and reported results on this list. Ccomp makes a difference for reflections off the driver (try simulating a serially terminated or unterminated net). Ccomp always makes a difference for a receiver. Hope that helps, Todd. Todd Westerhoff Signal Integrity Engineer Hammerhead Networks 5 Federal Street - Billerica, MA - 01821 email:twester@xxxxxxxxxxx - ph: 978-671-5084 ============================================ "It's a long, long road, from which there is no return While we're on our way to there, why not share And the load, it doesn't weigh me down at all He ain't heavy, he's my brother" - Sidney Russell and Robert Scott, (C) 1977 Harrison Music Corp., Jenny Music (ASCAP) -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Timothy Coyle Sent: Tuesday, May 07, 2002 2:25 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Ccomp in HSPICE Hi, I am trying to see the effects of different Ccomp values of an IBIS output buffer in HSPICE. When I change Ccomp and re-run simulations, I see no difference. I'm sure I'm leaving something out, so if anyone can shed some light on this it would be appreciated. Thanks in advance, Tim ------------------------------------------------------------------ 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 ------------------------------------------------------------------ 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