Hi, Please forgive the shameless plug to my website and software in advance but I would like to find the formula for embedded diff pairs. I wrote a calculator a while ago that works well for diff pairs butt it is only good for external layered diff pairs. The formula came from an Analog Device's datasheet and does seem to be accurate. Does anyone know where I can get the formula? Thank you Ken <http://saturnpcb.com/Software.htm> http://saturnpcb.com/Software.htm#2 _____ Saturn PCB Design, Inc. Kenneth J. Wood CID 2737 Bishop Lane Deltona, Fl 32725 Phone: 407-340-2668 email: <mailto:[log in to unmask]> [log in to unmask] www.saturnpcb.com <http://www.saturnpcb.com/> --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------