[SI-LIST] 3D-em simulation and terminations: macromodelling
- From: Gregory R Edlund <gedlund@xxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Wed, 7 Jan 2009 08:44:18 -0600
Istvan,
I included two chapters on E/M modeling in my book "Timing Analysis and
Simulation for Signal Integrity Engineers." It is more of a "how-to" book
than a strong theoretical text. I did include an appendix with a bit of
theory, though. You can check out a free Safari copy on Amazon - try
before you buy.
I've done quite a bit of 3D E/M modeling and correlation to hardware for
connectors, so I have a sense for what modeling techniques produce a good
match to hardware. I apologize for the shameless self promotion, but
maybe it will help you.
Greg
Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im
Auftrag von Istvan Nagy
Gesendet: Montag, 5. Januar 2009 22:34
An: si-list@xxxxxxxxxxxxx
Betreff: [SI-LIST] 3D-em simulation and terminations: macromodelling
hi
if i simulate a pcb structure (a microstrip trace) with an 3d
electromagnetics simulator to create a macromodell (s-parameter touchstone
file), then do i have to connect terination resistors in the em simulation
setup? or all the ports in all simulators are automatically terminations
too? do i have to use the same term.resistor value in system simulation
too (when using the macromodel. example in Agilent ADS or spice) to get
accurate results?
the problem is that in the em simulation we can not use the correct
termination, since it comes with using IBIS buffer models and those are
not compatible with any of the EM simulators, they can be connected in a
circuit simulator only. so do macromodelling: first EM simulation, create
macromodel, then system simulation with the other elements of the signal
path.
I was thinking:
if the S parameter data ( S21(f) ) should depend on the actual
termination?
if we change the termination of a transmission line, then it changes the
reflections (matched, unmatched...as we studied in the school). is it the
same when we use an s-param (touchstone) macromodel instead of the real
tline?
if i dont terminate in the em simulator, then the strong reflections will
cause strong loss and not-flat response, and that loss will go into the
s-param file. then if i connect correct termination in the system level
simulation, it will not to fix those reflections/loss anymore.
am i right?
so, how much usable is an s-parameter macromodell, and macromodelling
anyway?
Istvan Nagy
CCT
Greg Edlund
Senior Engineer
Signal Integrity and System Timing
3605 Hwy. 52 N Bldg 050-2
Rochester, MN 55901
gedlund@xxxxxxxxxx
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