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gEDA-user: Trace Impedance with wcalc
Hello @all,
I done a Mainboard Schematic with gEDA, now I have to layout the hole
thing,
because I need LVDS,GigE,... I need to care about trace impedance.
Because of this, I used wcalc to calculate trace impedance, but now I have
some (general) questions about impedance calculations.
For GigE e.g. I need 55Ohm Single- and 100Ohm Diff. Impedance.
I used wcalc "Microstrip Analysis" and PCB Values to get the Single-Imp
(55Ohm).
(w=0,55mm;l=20mm;h=0,38;Er=4,6;Tand=0,015;Tmet=35um,Rho=1,72e-8;100MHz)
But now I want to get the diff. Impendance with "Coupled Microstrip
Analysis", the only Variables I can influence are w,s,l.
If I using w=0,55Ohm (from Single Imp.) it's impossible to get 100Ohm
diff. Imp..
Minimal Spacing and Trace width is 0.15mm, if I'm using this, I get nearly
100Ohm diff., but then my single Imp. is also 100Ohm.
So, please - just give me a hint. Do I completly misunderstood wcalc!?
I really need to get this pcb to fab... - Any tips would be greatly
appreciated.
Greetings,
_______________________________________________________________________________________________________________________
cand. Dipl.-Ing. (FH) Marcel Schmedes
Research & Technology
Cockpit Cabin Control
Diehl Aerospace GmbH
An der Sandelmuehle 13
D-60439 Frankfurt/Main
Phone: +49 (0) 69 5805-1712
Mail: marcel.schmedes.extern@xxxxxxxxxxxxxxxxxx
www. http://www.diehl-aerospace.de
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