RE: [SI-LIST] : 200 ohms

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From: Jian X. Zheng (jian@zeland.com)
Date: Fri Dec 01 2000 - 11:01:29 PST


Hi:

I think Ray's calculation is about right. We can use some high performance
electromagnetic simulator to confirm it. However, for a substrate as thick
as 250 mils, I would suggest you not to use it over 2 GHz. For a 1-G Bit per
second transmission, the base band is 2 GHz and the harmonics may go up to
10 GHz. If you want to use a substrate as thick as 250 mils, the
transmission rate should not exceed 250 M Bit per seconds if we need to
consider the harmonics.

For a microstrip circuit as thick as 250 mils, it will create much
radiation, dispersion and cross-talk when the frequency goes to as high as 2
GHz or higher.

Best regards,

-----------------------------------------------------------------------
Jian-X. Zheng, Ph.D
Zeland Software, Inc., 48890 Milmont Drive, 105D, Fremont, CA 94538, U.S.A.
Tel: 510-623-7162, Fax: 510-623-7135, Web: http://www.zeland.com
---------------------------------------------------------------------

> -----Original Message-----
> From: owner-si-list@silab.eng.sun.com
> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of Ray Anderson
> Sent: Friday, December 01, 2000 10:22 AM
> To: seandm@mmspec.com; si-list@silab.eng.sun.com
> Subject: Re: [SI-LIST] : 200 ohms
>
>
>
> Not sure what you are trying to do, but if you go microstrip,
> a 4 mil wide trace on a 250 mil thick FR4 substrate will give
> you about 200 ohms impedance. (according to apsim RLGC)
>
> -Ray
>
> >
> > Anyone able to achieve 200 ohms on .250 thick board before? If
> not what is
> > the closest achievable board impedance within reason?
> >
> > Sean Murray
> > General Manager
> >
> > M&M Specialties, Inc.
> > 1236 W. Southern Ave. #106
> > Tempe, AZ 85282
> > 1-800-892-8760 x105
> >
> > www.mmspec.com
> >
> >
>
>
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