Help identifying a capacitor

Tony Duell ard at p850ug1.demon.co.uk
Tue Jul 17 16:14:59 CDT 2007


> Get the cap as close to the chip as you can: think of the trace as a
> (really low resistance) resistor: the resistance PS-to-cap is is much
> larger than resistance cap-to-chip and bingo! low-pass filter.

Actually, it's the inductive reactance of the trace/PSU connections 
that matters here. With high-frequency signals -- this doens't mean a 
high clock rate necessarily, it means a fast ris-time edge -- you can 
get significant voltage drop from very small 'inductors', like the 
connction from the chip to the PSU.

-tony



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