John, I tried your cases with pure 50 ohm lossless t-lines and a 50 ohm termination on the end. I get a delay of 6.3200ns in all three cases. Either with or without a 50 ohm source impedance. I tried two different version of HSPICE. Identical results. Were you using Berkeley or Hspice, and what version? Regards, Andy > I just did some experiments with pure 50 Ohm t-lines. > > For 40 inches at td=158p/in. td should equal 6.32ns. > > When I simulate a single 40 inch tline I get 5.89 ns 50% to 50% delay > with a > 100ps edge(0 to 100%) input. > > 10 sections of 4 inches each yields td=6.16ns > 20 sections of 2 inches each yields td=6.3 ns. > > I'd appreciate a reality check on this. I terminated the far end of > the > tline in 50 Ohms to ground. > ------------------------------------------------------------------ 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