[SI-LIST] Re: How to calculate/obtain footprint ind/cap characteristic for 402, 603, etc?

  • From: Scott McMorrow <scott@xxxxxxxxxxxxx>
  • To: tom_cip_11551 <tom_cip_11551@xxxxxxxxx>
  • Date: Thu, 05 Jun 2008 18:05:22 -0400

Tom
With all due respect, a capacitor mounted on a PCB is a very complex 
mixed TEM/Quasi-TEM/non-TEM 3D structure, which is not amenable to first 
order spice approximation without a large amount of work.  You can start 
with papers we've placed on our website, where we have shown the first 
principles necessary to calculate mounted capacitor inductance, 
correlated our models to measurement, and have further correlated 
measurements to full 3D full-wave structural simulation of a capacitor.

http://www.teraspeed.com/publications.html

A few that you might look at are:

*//Using Full Wave Solvers for Practical Analysis of Capacitor Mounting 
Structures *

*Considerations for Capacitor Selection in FPGA Designs *

*Bypass Capacitor Inductance, Data Sheet Simplicity to Practical Reality *

*Bypass Filter Design Considerations for Modern Digital Systems *

*System Considerations for Bypass Filter Designs *

* Impact of PCB Stack-up and Capacitor Via Design In Power Distribution 
Design *

*High Performance FPGA Bypass Networks*

**
best regards,

Scott


Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax

http://www.teraspeed.com

Teraspeed® is the registered service mark of
Teraspeed Consulting Group LLC



tom_cip_11551 wrote:
> Hi,
>
> I am trying to determine an optimum decoupling strategy. I have found 
> lots of manufacturers data conerning capacitor models, from Murata and 
> others. But I keep thinking that these models can't possibly take into 
> consideration the layout footprint, because of process, material and 
> other variations, like the layer height above copper.
>
> So, when attempting to model a capacitor in spice or other, what is a 
> good strategy in trying to take into consideration the footprint itself?
>
> Yes, I do realize that in some cases, a 3D model can be created, but 
> that can be very time consuming and I am really only talking about a 
> first order spice approximation.
>
>
> Thank you to all who respond.
>
> Tom
>
>
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