In a message dated 10/8/2002 10:11:47 AM Pacific Standard Time, rmittal@xxxxxxxxxxxxx writes: > Continuing on the same topic - I was wondering if you would say the same > thing for 10G. At 10G, I think stripline will not be as effecient because > you will have to use vias and unless you make 50ohm vias, the distortion > from the vias will be too significant. I have always used microstrip at > 10G. > Do you agree? As usual, "it depends." If you mean RF at 10 GHZ versus 10 Gbps the digital folks talk about that really means 5 GHz fundamental, most RF circuits at this frequency are relatively isolated from other circuits (sometimes even compartmentalized stage-to-stage) and contained within a small, RF-tight enclosure. Microstrip is great for these conditions. If other circuits are immediately adjacent, stripline in PCB pseudo-cavity construction (for isolation and shielding) is appropriate. And, yes, 50-Ohm via construction IS needed for maximum efficiency. At these frequencies, teflon-impregnated glass dielectric is generally needed, especially if efficiency is critical to successful circuit performance. For the digital case, and especially for a backplane, the approach I would recommend is differential stripline with buried vias in teflon-impregnated glass dielectric. Multiple pairs are generally involved; therefore, crosstalk considerations are critical and lead one to stripline rather than microstrip. Lots more can be said, but I have to go. Mike Michael L. Conn Owner/Principal Consultant Mikon Consulting *** Serving Your Needs with Technical Excellence *** ------------------------------------------------------------------ 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