From: Tadashi ARAI ([email protected])
Date: Wed Jun 21 2000 - 17:18:28 PDT
Howdy All,
I have attached 2 waveforms what show crosstalk noise with/without guard
traces, our staff's (old) analysis by XTK.
Configurations are;
Surface of 4 layer board (microstrip),
Dielectric (FR4) height : 4.33mils
Copper Foil : 0.709mils
5 traces;
Width : 5mils
Space(edge-edge) : 20mils
Length : 8inchs
Center one is inactive, measured trace (victim).
Another 4 are given stimulus simultaneously (aggressor).
These show FEXT results only.
5mil_L_d.gif:
inserting guard traces of 5mils width between each traces.
Red: No guard traces (only AIR gap)
Blue: with guard traces modeled as transmission line with via of 1"
each
Black: with guard traces modeled as ideal ground
18mil_L_d.gif:
inserting guard traces of 18mils width ("Flood") between each traces.
Red: No guard traces (only AIR gap)
Blue: with guard traces modeled as transmission line with via of 1"
each
Black: with guard traces modeled as ideal ground
However I know these analysis are not properly modeled and we have much
to do, I guess we have got some ideas what couplings tend to.
At least, we can avoid to make layout designer change our target
geometry arbitrary with guard traces :).
And some one please tell me the inadequacy of guard traces at the range
of our design - around 1GHz.
Regards,
//// /// // / / / / / / / / / /
Tadashi Arai//Platform Developing Dept.,Desktop Prd Div. Fujitsu Limited
[email protected] TEL:+81-42-370-7624 Inagi-shi, Tokyo, Japan
/ / / / / / / / / / / // ///
On Tue, 20 Jun 2000 08:15:59 -0800
Mail from [email protected] described as below:
> Hi Tadashi,
>
> Did you run a simulation with only an airgap between the traces (same
> distance you have with the guard traces on the board) to show you what
> your crosstalk would be with only the added separations? Try that, and
> report back what you find. (Pssst, guard traces aren't necessary) :)
>
> -M-
>
>
**** To unsubscribe from si-list or si-list-digest: send e-mail to
[email protected]. In the BODY of message put: UNSUBSCRIBE
si-list or UNSUBSCRIBE si-list-digest, for more help, put HELP.
si-list archives are accessible at http://www.qsl.net/wb6tpu
****
This archive was generated by hypermail 2b29 : Wed Nov 22 2000 - 10:50:42 PST