AVR-Chat

Hmm ... this technique is extensively used in UHF and microwave circuits.
You will often see two or three bypass capacitors of different values at
each point where a power lead or trace approaches an active device.

Zack

On Thu, Oct 11, 2012 at 7:59 AM, bayramdavies <Yahoo37849@ecrostech.com>wrote:

> **
>
>
> --- In AVR-Chat@yahoogroups.com, Zack Widup <w9sz.zack@...> wrote:
>
> > .. bypass the power ... with several
>
> > capacitors in parallel - maybe a few
> > microfarads in parallel with a 1000
> > pF and a 10 pF.
>
> Using different values of capacitors in parallel for high-frequency bypass
> is not a good idea. The smaller capacitors can form parallel resonant
> circuits with the parasitic inductance of the larger capacitors and
> increase the impedance at high frequency. The way to do it is to use one
> sufficiently large capacitor with the lowest practical parasitic impedance
> and pay close attention to parasitics in routing.
>
> You can, of course, add an electrolytic somewhere or other to help with
> low-frequency stability.
>
> Graham.
>
>  
>


[Non-text portions of this message have been removed]