[SI-LIST] Re: Capacitors at high frequency
- From: steve weir <weirsi@xxxxxxxxxx>
- To: Alvaro alkschbirs <alvaro.alkschbirs@xxxxxxxxx>
- Date: Sat, 23 Oct 2010 17:37:06 -0700
Alvaro, I will add to the other answers:
1. In low-cost, low layer count PCBs the capacitors are often important
past 1GHz. In multilayer boards with large area thin power cavities,
the capacitors often lose dominance well below 200MHz.
2. In signal coupling applications, the idea is to make the mounted
capacitor appear as transparent as possible. The most important thing
that you want to concern yourself with is designing the capacitor mount
properly so that it doesn't present a big impedance discontinuity.
Steve
Alvaro alkschbirs wrote:
> Hi all,
> I have a question about power (de)coupling and ac coupling capacitors;
>
> Situation 1:
> Thinking about capacitors at high frequency, According to what I've read,
> the power supply (de)coupling discrete capacitors works until some hundred
> of MHz. Above this, the inductance goes dominant and the power charge
> capacity goes down.
>
> Situation 2:
> Now, thinking about this same discrete capacitor working as AC coupling on
> 1Gb/s or 3,125Gbp/s signals. I have done this in my projects (using 0402
> capacitors) and no error have been reported at this signals.
>
>
> Q1. What do you think about it ?
>
> Q2. Why the dominant inductance is a problem in situation 1, and not for 2 ?
>
> Thank you very much,
> Álvaro Alkschbirs
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
> List technical documents are available at:
> http://www.si-list.net
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
>
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
>
--
Steve Weir
IPBLOX, LLC
150 N. Center St. #211
Reno, NV 89501
www.ipblox.com
(775) 299-4236 Business
(866) 675-4630 Toll-free
(707) 780-1951 Fax
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
