Re: gEDA-user: Eliminate separate Vcc planes?

[Gabriel Paubert <paubert@xxxxxxx>]

On Mon, Oct 19, 2009 at 06:43:42PM -0500, Darrell Harmon wrote:
> On Mon, Oct 19, 2009 at 5:27 PM, Dan McMahill <dan@xxxxxxxxxxxx> wrote:
> > my recent experiences are more in line with Larry's.  Most C for a given
> > package and voltage seems to be the best meaning that above resonance it
> > is no worse than smaller capacitance value devices and below resonance
> > it is better.  And yes, this seems to fly in the face of what has been
> > recommended in the past.  I've not done any careful measurements of
> > older technology bypass caps but I wonder if this is one of those
> > "rules" which became obsolete 15-20 years ago and no one noticed...
> >
> > -Dan
> 
> I have done some testing of various passives (mostly 0402) and came to
> the conclusion. I tested both shunt and series capacitors on a 50 ohm
> transmission line with a VNA. What was most interesting to me was that
> the large value capacitors performed better as series coupling caps
> than the small ones. The single layer caps in the 1 to 100 pF range
> frequently had parallel resonances in the 10 to 30 GHz range. Most of
> the multilayer caps (10 nF to 1 uF) performed well to at least 30 GHz.

And for the shunt case?

Some manufacturers (ATC, Dielectric Labs) also offer specific broadband 
coupling capacitors, did you try them? 

	Gabriel


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