Hello Mitch, If the crosstalk model is based upon cap coupling the output of a series L and shunt C voltage divider, then crosstalk will increase with rise time up to a point and then start decreasing as the equivalent coupling cap between traces approaches an open circuit. I can't be sure without knowing what the Automata model is, but I think this explanation comes pretty close to whats going on. The tip-offs are negative crosstalk values from Automatas calculator, and from the output calculation of a series L shunt C divider above resonance. The negative values only mean that the crosstalk signal is 180 degrees out of phase with the source. Hope this helps! John. ----- Begin Included Message ----- HELP! The engineer I work with has some issues I am hoping someone can enlighten me on. > I have been using Automata in the past but stopped becuase something > doesn't seem right about the results it gives. Maybe I am wrong but > shouldn't the crosstalk increase when the signal rise time increases > if all else is held constant? > When I use the Automata Engineering Tools for doing lateral crosstalk > calculations the slower the rise time the larger the crosstalk result > becomes. Just doesn't seem right to me. Again, maybe I'm wrong! Here is two calculations from Automata: Automata's Lateral Crosstalk Modeling You submitted the following name/value pairs: Er = 4.3 h1 = 8 h2 = 8 t = 1 Oz w = 6 sx = 6 length = 2 **** risetime = 1.9 **** The crosstalk = 24.9 mv/v ---- Automata's Lateral Crosstalk Modeling You submitted the following name/value pairs: Er = 4.3 h1 = 8 h2 = 8 t = 1 Oz w = 6 sx = 6 length = 2 **** risetime = 3.1 **** The crosstalk = 31.9 mv/v ---- Does this seem correct to you? Thanks in advance for any help. ----- End Included Message ----- *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************