- Jan 1, 1970
Well, if we generously assume that an ADC that fast could have a 5V
input range, 1 LSB at 20 bits is 5 uV, and the quantization noise is
1/sqrt(12) times that, or 1.4 uV. In a 100 MHz bandwidth, that's
140 pV/sqrt(Hz). In real life, the input structure would have to be
several times faster than that in order to settle to that accuracy in
the time available, putting the maximum input noise down in the
50 pV/sqrt(Hz) range, not counting the effects of input capacitance.
Good luck with that.
Irritated yelling mode...You have just demonstrated once again WHY I
re-derive EVERYTHING! I NEVER trust 'cookbook' equations, especially
after getting severely burnt by an article in EDN showing 'cookbook'
values for a simple 'what's its name? filter [the simple 5-pole low pass
type using two 2N3904's in series]. Whereupon, I was forced to rederive
ALL the values for both Butterworth AND Tschebyshev(sp?) *and* using an
HP calculator with reverse polish input (spit, spit, curse begone!) I
'optimized' a response to obtain values and voila! worked. But that
little effort caught me on a late Friday [deadline Monday morning] to
make a filter that worked! All weekend!
I HATE PACKAGED FORMULAS!!! I have NO idea what these numbers you gave
me should mean to me.
Sorry? LOL! I actually read that out loud for effect.
So apart from posturing, what do you actually disagree with, and why?
Dr Philip C D Hobbs
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net