Thanks for the info on ΔΣ converters. It connects several things I knew about.
Now I need to study up on the area of computation that clover lives in.
Now I need to study up on the area of computation that clover lives in.
I dare say that the most common AD converters are simply delta-sigma converters, especially if 1MHz conversions is fast enough for your tasks.
To get into the 100MHz or above speed (ie: Oscilloscopes, Software defined Radios, etc. etc.) you need to use other techniques.
That gets back to my original point. The spectrum analyzer went into the gigahertz range. I don't think it was delta sigma. It was some multiple sample thing that only worked in the frequency domain.
I distinctly remember that Delta-Sigma was a slow-type of ADC. And I guess I confused it with the one in the ATMega328p.
The ATMega's ADC is pretty slow, like 15ksps at full precision, so I can see why you'd think that!