Hi Jim, the issue with 90 degree bends comes up pretty regularly. The basic answer to that is - given typical trace dimensions for high-speed digital signals (trace widths a few mils) the impact on signal integrity is very minimal unless you have a huge number of those bends in your line. The main issue with the design yoou descibe is going to be the via parasitics and the mounting parasitics of your termination resistor. That's the place to be worried about. Via stubs, distance to the groung return via, resistor pad layout etc. are things to think carefully about. Wolfgang otter30@xxxxxxxxxxxxx Sent by: si-list-bounce@xxxxxxxxxxxxx 02/27/2009 08:08 AM To <si-list@xxxxxxxxxxxxx> cc Subject [SI-LIST] 180 degree turns in high speed lines Hello, Has anyone had experience with high speed traces that travel in one direction on an inner layer of a pcb, and then transition to the top layer termination thru a via and then change direction 180 degrees? The distance traveled on the top layer is short - just a short connection between a termination resistor and the ic pins, but it's the turn that concerns me. After all the debate through the years on 90 degree turns, I'm interested in your opinions. Thanks, Jim ------------------------------------------------------------------ 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.net 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.net 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