Hi! I tried to do some simulation in HSPICE on module connectors connecting daughter card with the main board. There is one problem I encountered related to local ground and global ground node. Intuitively, I define the ground on the main board as node "0" in HSPICE. The input ground node of connector is tied to "0" through very small resistor. At the output side, I used a node "module_ground", which is linked with "0" on main board through connector model (parasitic RLCs). At the daughter card side, I then use this "module_ground" as the reference point for device, transmission line, etc. This actually simulate the real life and I expect to find out the noise on the "module_ground" due to inductive/resistive pins through connectors. However, in my simulation, I saw excessive noise (high frequency and large amplitude, which is definitely numerical noise rather than real thing) using connector model from one vendor, and I got error message as "inductor/voltage loop" using connector model from another vendor. By changing reference node on daughter card from "module_gnd" to "0", the error is gone. Wonder whether you have any experience to share on such problems, especially with HSPICE. Thanks Perry -- Perry Qu Product Integrity | 600 March Road Alcatel Canada | Ottawa, ON K2K 2E6, Canada DID: (613) 7846720 | FAX: (613) 5993642 ------------------------------------------------------------------ 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