RE: [SI-LIST] : Cross hatched planes

=?Big5?B?Sm9obiBMaW4gKKpMtMK31yk=?= (John@quantatw.com)
Mon, 21 Jun 1999 09:14:19 +0800

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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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RE: [SI-LIST] : Cross hatched planes

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.           &n= bsp;       ~
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?




**** To unsubscribe from si-list: send e-mail to = majordomo@silab.eng.sun.com. In the BODY of message put: UNSUBSCRIBE = si-list, for more help, put HELP.  si-list archives are accessible = at http://www.qsl.net/wb6tpu/si-list ****

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