FFT for ADC output

glen herrmannsfeldt <gah@ugcs.caltech.edu> wrote:
Snip, I wrote:

> Now, how many electrons are stored on a typical
> capacitor in a DRAM array these days?

OK, answering my own question...

A google search for dram cell capacitance indicates 25fF
for a 256Mbit DRAM in August 2002.  I suppose it might
have shrunk since then, but...

1fF*1V=1fC=1e-15C/1.6e-19C/electron= about 6250 electrons.

One should be able to build analog voltage storage devices
with much larger capacitors, though, so sampled analog
signal processing could be done with much larger numbers
of electrons.  It would seem, though, that 24 bit A/D
and D/A likely to much better than analog signal processing.

-- glen