[SI-LIST] Re: Capacitors and Anti-resonance
- From: "Lee Ritchey" <leeritchey@xxxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Thu, 9 Oct 2003 09:32:05 -0700
Daniel,
The book I promised is finally in print! It is titled "Right the First
Time, A Practical Handbook on High Speed PCB and System Design". You can
preview it and order it on my web site www.speedingedge.com.
Hope you like it.
Lee
> [Original Message]
> From: Paradis, Daniel <Daniel.Paradis@xxxxxxxxxx>
> To: leeritchey@xxxxxxxxxxxxx <leeritchey@xxxxxxxxxxxxx>;
<si-list@xxxxxxxxxxxxx>; Paradis, Daniel <Daniel.Paradis@xxxxxxxxxx>
> Date: 7/30/2003 10:33:02 AM
> Subject: [SI-LIST] Re: Capacitors and Anti-resonance
>
> Lee
> Thanks for your feedback.
> I will try to get the paper.
> Do you have the URL ?
> Who will be the publisher of your book?
> I am always interested by the latest.
>
> Regards
> DP
>
> -----Original Message-----
> From: Lee Ritchey [mailto:leeritchey@xxxxxxxxxxxxx]
> Sent: Wednesday, July 30, 2003 1:07 PM
> To: si-list@xxxxxxxxxxxxx; Paradis, Daniel
> Subject: RE: [SI-LIST] Re: Capacitors and Anti-resonance
>
>
> Daniel,
>
> There is a much better paper on this done by the engineers at University
of
> Missouri Rolla. It demonstrates that the location of capacitors of any
> value makes little or no difference at the frequencies involved in edges
of
> that speed. Their self inductance renders them ineffective. The plane
> capacitor you intentionally build into the PCB is the supplier of those
> switching currents.
>
> I have repeated those tests with a fellow engineer and demonstrated the
> same thing. Our results will be published in my new book, "Right the
First
> Time, a Practical Handbook on High Speed Design'.
>
> The UMR paper is: Hubing, Todd H. etal, "Power Bus Decoupling on
> Multilayer Printed Circuit Boards" IEEE Transactions on Electromagnetic
> Compatibility, Vol. 37, NO 2, May 1995.
>
> Lee
>
>
>
> Lee Ritchey
> leeritchey@xxxxxxxxxxxxx
> Why Wait? Move to EarthLink.
>
>
> > [Original Message]
> > From: Paradis, Daniel <Daniel.Paradis@xxxxxxxxxx>
> > To: si-list@xxxxxxxxxxxxx <si-list@xxxxxxxxxxxxx>
> > Date: 7/29/2003 4:55:42 PM
> > Subject: [SI-LIST] Re: Capacitors and Anti-resonance
> >
> > Well I did my homework
> > in "High-Speed Digital Design" by H. Johnson & M. Graham. (12th
printing)
> > It is said p. 260...
> > " a rising edge of 1ns propagating in FR-4 material has a length of
about
> l=
> > 6 in.
> > No benefit will be derived in this example from a capacitor grid spaced
> > further apart than l/12 = 0.5 inch"
> >
> > Now if I follow the same logic...
> > for a 1 ns system I can use different values of caps for every sections
>
> if
> > they are spaced apart by more than 0.5inch
> > without risking any antiresonance effect.
> >
> > Does it make sense?
> > Anybody?
> >
> >
> > > -----Original Message-----
> > > From: Paradis, Daniel
> > > Sent: Tuesday, July 29, 2003 9:58 AM
> > > To: 'si-list@xxxxxxxxxxxxx'
> > > Subject: Capacitors and Anti-resonance
> > >
> > > I started to use only 0.1uF decoupling caps on our latest designs.
> > > This is to avoid the anti-resonance effect that occurs when using 2
> > > different caps near each other.
> > > The rule of thumb is to use the largest cap available for the
package. >
> >
> > > So far I got good results, but I was wondering....
> > >
> > > Is-there a simple way to determine the distance between 2 different
> > > decoupling caps beyond which there is no anti-resonance effect?
> > >
> > > In other words..
> > > Say that I stick to this general rule of using only one cap.
> > > It seems to me that there could be exceptions to that rule.
> > > In the case of a high speed clock buffer for instance;
> > > I could need 0.0047uF instead of 0.1uF
> > > If this clock buffer is located far from other parts of the design.
> > > Can I avoid anti-resonance?
> > >
> > >
> > > Daniel Paradis
> > > Staff Electrical Engineer
> > > Digital Subscriber Networks
> > >
> > > Scientific-Atlanta, Inc.
> > > 5030 Sugarloaf Parkway, ATL 1.3468
> > > Lawrenceville, GA 30042
> > > Tel: (770) 236-7896
> > > Fax: (770) 236-2449
> > >
> > >
> >
> >
> > - - - - - - - Appended by Scientific-Atlanta, Inc. - - - - - - -
>
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