[SI-LIST] Re: GND is perfect conductor?
- From: "Ingraham, Andrew" <a.ingraham@xxxxxxxx>
- To: "Signal Integrity Mailing List" <si-list@xxxxxxxxxxxxx>
- Date: Sat, 6 Sep 2003 12:59:33 -0400
The in-house field solver we had at Compaq/HP did not use perfect conductors
for ground. It rolls both the ground and signal conductor losses together
into the model you create. I would guess that many other field solvers do
the same.
SPICE t-line models (and W-line models are probably in the same boat) might
seem to have a perfect ground because you normally connect the reference
nodes at both ends together to the same ideal GND (node 0). But that's not
the same thing as treating the ground as ideal.
T-line models can be thought of as being transformer coupled; what comes out
on the far end is isolated from ground and you get the same differential
output signal whether you connect the far end's reference node to GND or to
any other arbitrary node. The SPICE t-line model represents only the
differential propagating mode, but it can correctly include ground losses
with that mode. The Berkeley SPICE documentation talked about using two
T-line models to represent both even and odd modes of a single two-conductor
transmission line.
Regards,
Andy
------------------------------------------------------------------
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
Other related posts:
