RE: [SI-LIST] : Cross hatched planes

fabrizio zanella (fzanella@fishbowl02.lss.emc.com)
Thu, 24 Jun 1999 8:13:14 -0400

Syed, I need to model a diamond shaped cross hatched plane for a flex
circuit. We have the Viewlogic tools, so if you have an XFX example you
could also send me that would be great.
Thanks and regards,

Fabrizio Zanella
EMC, Hardware Engineering
171 South Street
Hopkinton MA 01748
fzanella@emc.com
508-435-2075, x4645
FAX 508-497-8741
-------------
Original Text
From: "Syed Huq" <shuq@cisco.com>, on 6/24/99 5:21 AM:
To: smtp@Eng@EMCHOP1[<si-list@silab.eng.sun.com>]
Cc: smtp@Eng@EMCHOP1[<shuq@cisco.com>]

John,

You may not be able to define a circular shape but a diamond shape is
possible.
I will try to send you an example. XFX models the hatched ground quite
accurately.

Regards,
Syed.

>
> Syed,
>
> I use XFX to model the cross hatch also. However I realize that the
meshed
> ground defined in the XFX is only good for rectangle.
> It is quite limited. I asked viewlogic's FAE about diamind or circular
> shapes but got not answer.
>
> How do you deal with this problem with XFX ? Is XFX accurate enough for
> hatch ground?
>
> Best Regards,
>
> John Lin
> CAE Engineer
> Quanta Computer Inc.
>
>
>
> -----Original Message-----
> From: Syed Huq [mailto:shuq@cisco.com]
> Sent: Saturday, June 19, 1999 5:09 AM
> To: si-list@silab.eng.sun.com
> Cc: shuq@cisco.com
> Subject: Re: [SI-LIST] : Cross hatched planes
>
>
> Hello,
>
> If you are using XFX(2-D from Quad), you can model the cross hatch using
> MESHED_GROUND. For example:
>
> MESHED_GROUND HORIZ_PLANE y: 27.80 29.20 P_X: 15.0 A_X: 10.0 P_Z: 15.0
A_Z:
> 10.0
> MESHED_GROUND HORIZ_PLANE y: 0.000 1.400 P_X: 15.0 A_X: 10.0 P_Z: 15.0
A_Z:
> 10.0
>
> Impedance becomes a function of your cross hatch geometry plus more..
>
> We have done this sort of study.
> Regards,
> Syed.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Syed B. Huq shuq@cisco.com ~
> Signal Integrity Engineer(ELB) ~
> Cisco Systems, Inc. ~
> Ph:(408)525-3399 Fax:(408)526-5504 ~
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> >
> > I have a question regarding high frequency (over 500MHz) signals
running
> > over ground planes that are cross hatched, which is commonly done on
flex
> > circuits. The issue is how to accurately model the characteristic and
> > differential impedance for the flex circuit traces. If, for example, I
> use
> > a 2D field solver (where I assume an ideal ground plane) and am
designing
> > for 100 ohms differential impedance, what percent increase in impedance
> > should I expect if the ground plane will actually be cross hatched?
>
>
>
>
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