[SI-LIST] local and global ground

Hi!

I tried to do some simulation in HSPICE on module connectors connecting
daughter
card with the main board. There is one problem I encountered related to
local ground and global ground node. Intuitively, I define the ground on
the main board as node "0" in HSPICE. The input ground node of connector
is
tied to "0" through very small resistor. At the output side, I used a
node "module_ground", which is linked with "0" on main board through
connector model (parasitic RLCs). At the daughter card side, I then use
this "module_ground" as the reference point for device, transmission
line, etc. This actually simulate the real life and I expect to find out
the noise on the "module_ground" due to inductive/resistive pins through
connectors.

However, in my simulation, I saw excessive noise (high frequency and
large
amplitude, which is definitely numerical noise rather than real thing)
using connector model from one vendor, and I got error message as
"inductor/voltage loop"
using connector model from another vendor.

By changing reference node on daughter card from "module_gnd" to "0",
the error is gone.

Wonder whether you have any experience to share on such problems,
especially with HSPICE.

Thanks

Perry

--
Perry Qu

Product Integrity         |      600 March Road
Alcatel Canada            |      Ottawa, ON K2K 2E6, Canada

DID: (613) 7846720        |      FAX: (613) 5993642
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