From: Larry Miller (email@example.com)
Date: Mon Jun 12 2000 - 13:52:42 PDT
If you got, like, 65 ohms the problem is that your dielectric thickness is
too big. If you want 8-mil traces you should be more like 0.005".
There is a handy-dandy impedance calculator available for free download at
UltraCad.com that I use all the time for "close enuf" PCB trace
> -----Original Message-----
> From: Sean Murray [SMTP:firstname.lastname@example.org]
> Sent: Monday, June 12, 2000 1:35 PM
> To: 'email@example.com'
> 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.
> 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: firstname.lastname@example.org
> **** To unsubscribe from si-list or si-list-digest: send e-mail to
> email@example.com. 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
**** To unsubscribe from si-list or si-list-digest: send e-mail to
firstname.lastname@example.org. 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 - 10:50:35 PST