AVR-Chat

--- In AVR-Chat@yahoogroups.com, "bayramdavies" <Yahoo37849@...> 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.


As many as three capacitors per pin are recommended by Xylinx and Altera for decoupling FPGAs!

Leon