[SI-LIST] Re: Ground nodes in spice

  • From: Robert Haller <rhaller@xxxxxxxxxx>
  • To: fzanella@xxxxxxxxxxxx
  • Date: Thu, 27 Feb 2003 11:41:52 -0500

    I have a couple of points you should be  aware of.
1. You do not HAVE to tie all of the ground nodes set to zero, but if 
you don't
be prepared to accurately model your interconnect, connectors, decoupling
and signal to return ratio's.
2. When you are displaying an Eye pattern on a remote board not tied to 
use the remote reference for your signals reference.
3. If you are using a connector model that contains partial inductances 
you will violate
the assumptions of the field solver used to create that model if you  
ground (tie to zero)
both sides of the connector.


Robert J. Haller (rhaller@xxxxxxxxxx)
Principal Consultant
Signal Integrity Software Inc.
6 Clock Tower Place, Suite 250
Maynard, MA 01754
Phone: (978) 461-0449, ext 15

Fabrizio Zanella wrote:

>I have a question regarding backplane simulations of serial 8b/10b
>signals, running 2.5Gbs and above.  Does it matter whether the ground
>nodes of the daughtercards and backplane are all set to 'zero' or to a
>floating node for eye pattern results?
>Fabrizio Zanella
>Principal Hardware Design Engineer
>Broadbus Technologies

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