For years I've encountered systems with balanced differential signals that transition to 2 single ended lines in a PWB. For example, an RS422 signal on a 100 ohm diff. pair wire that connects to a PWB that then routes it as a loosely-coupled pair of 50 ohm striplines. This seems to work fine for these slower edge rate systems. I'm starting to see attempts to do the same thing with sub ns edge rate signals in the 100s of MHz and GHz range. This bothers me seeing a transition between the 2 modes (probably poor term to select) without seeing a transformer or other balun-like device. Should I be concerned? If this is a problem, how do you simulate it (tools)? Thanks, Brad Henson,Raytheon ------------------------------------------------------------------ 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