RE: [SI-LIST] : DIFF PAIRS

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From: Salvador Aquinaga (Salvador_Aguinaga@3com.com)
Date: Mon Jun 12 2000 - 15:09:22 PDT


Sean,

For edge-coupled, symmetrical stripline pairs you will need a
separation >15 mils. Or if you want them strongly coupled, you
will have to increase the dielectric thickness to 10 mils on each
side of the Signal layer. Both these will give you (roughly)
Z0 =3D 50 Ohms +/- 10% and Z0D =3D 100 +/- 10% (most likely just
under the target value, depending of the etching process).

Talk to your board vendor about their etch process to understand
the geometry of the finished (or etched) traces.

Hoping this is the kind of info you were looking for,

-- Sal Agui=F1aga Jr./3Com

Sean Murray <seandm@mmspec.com> on 06/12/2000 04:07:57 PM

Sent by: Sean Murray <seandm@mmspec.com>

To: Salvador Aguinaga/MW/US/3Com
cc:
Subject: RE: [SI-LIST] : DIFF PAIRS

=

--0__=hRK2aoqCw15f4tbV8wgA8YH6SzqBmU1HJsChFcl1LS3sFvj4Vo6fE2r8
Content-type: text/plain; charset=us-ascii
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weight is 1 oz. dk for CE is approx 3.7 I believe at 800 mhz, let's just
say it is.

> -----Original Message-----
> From: Salvador_Aguinaga@3com.com [mailto:Salvador_Aguinaga@3com.com]
> Sent: Monday, June 12, 2000 1:57 PM
> To: seandm@mmspec.com
> Subject: [SI-LIST] : DIFF PAIRS
>
>
>
>
>
> What is the signal Cu weight (.5 Oz, or 1 Oz, etc.)?
>
> What is the dielectric constant of CE for your given frequency?
>
>
> ---------------------- Forwarded by Salvador
> Aguinaga/MW/US/3Com on 06/12/2000
> 04:03 PM ---------------------------
>
>
> Sean Murray <seandm@mmspec.com> on 06/12/2000 03:34:53 PM
>
> Please respond to Sean Murray <seandm@mmspec.com>
>
> Sent by: Sean Murray <seandm@mmspec.com>
>
>
> To: "'si-list @silab.eng.sun.com'" <si-list@silab.eng.sun.com>
> cc: (Salvador Aguinaga/MW/US/3Com)
> Subject: [SI-LIST] : DIFF PAIRS
>
>
>
> Anyone have any thought on what to use for the following numbers.
>
> Material: CE
> Impedance: ZO of the differential trace is 50Ohm and ZOD of each
> differential pair traces is 100Ohm.
>
> I built a board using 8 mill traces with a 8 gap between the pair, and
> .008 gap between plane to sig and then plane.
>
> Numbers were not what I expected, fabhouse used Polar+fudge factor to
> give me the numbers.
>
>
>
> Regards,
> Sean Murray
> General Manager
>
> M&M Specialties Inc.
> 1236 W. Southern Ave. #106
> Tempe, AZ. 85282-4518
> Phone: (480) 858-0393 x105
> Cell: (602) 684-7859
> Fax: (480) 858-1882
> Email: seandm@mmspec.com
> WWW.mmspec.com
>
>

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