[hsdd] High-Speed Digital Design Newsletter

• From: "Dr. Howard Johnson" <howiej@xxxxxxxxxx>
• To: <hsdd@xxxxxxxxxxxxx>
• Date: Fri, 24 Jan 2003 15:02:04 -0800

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_____________________________________________________
BYPASS ARRAY MODEL

HIGH-SPEED DIGITAL DESIGN    ?  online newsletter  ?
Vol. 6  Issue 02

I'll be at DesignCon 2003 next week in San Jose,
learning lots of new things as always. Hope to see
you at the show. Ralph Cavin has me scheduled to
talk on a panel about University Education. I also
will appear with Henri Merkelo talking about the new
reality of multi-level transceivers for backplane
applications.

The following week brings another reprise of the
ever-popular High-Speed Digital Design seminar at
the Embassy Suites Hotel in Milpitas. See
www.sigcon.com for details.

______________________________________________________

BYPASS ARRAY MODEL

Daniel Paradis writes to the si-list:

Is-there a Mathcad model available to calculate the
impedance magnitude of a bypass capacitor array?

I am specifically referring to sec 8.2 of "High
Speed Digital Design".

______________________________________________________

Dr. Johnson replies:

Thanks for your interest in High-Speed Digital
Design.

This summer I received a very nice Excel spreadsheet
based on the approach outlined in section 8.2
equations.  The spreadsheet was developed by JP
Nicholls of Powerwave UK Ltd.

It takes into account the inductance of your power-
supply wiring, any bulk-decoupling capacitors, a
uniform bypass capacitor array, and the natural
capacitance of your power and ground planes.

JP's spreadsheet produces a beautiful color version
of my figure 8.9 showing the impedance of each
element and also the composite impedance of all four
elements taken in parallel. Once you see how it
works you can modify it to do lots of other
combinations.

The spreadsheet runs on Windows using Excel 2000. It
handles all the calculations quite nicely using the
complex-maths functions in Excel.

www.sigcon.com/pubs/news/PowerSystemImpedance.xls

I love the fact that this has been done on an Excel
spreadsheet because, as much as I like to use
MathCad, I must admit that Excel is much more widely
disseminated. Thanks, JP.

Best Regards,
Dr. Howard Johnson

______________________________________________________

Dr. Johnson is the featured signal integrity
columnist for EDN Magazine (http://www.ednmag.com).
We archive all his EDN archives at http://sigcon.com
under "Archives".

High-Speed Signal Propagation: More Black Magic is
now available for pre-sales at Barnes and Noble,
www.barnesandnoble.com

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