17 Jul
2007
17 Jul
'07
2:14 p.m.
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