Trying to learn a bit more about high-resolution ADC's

[senso]

Good night, to spend some time I decided to get my feet wet with some 16 bits ADC's, for now I have choosen the ADC161S626 from National/TI, the idea is to feed it with a 2.5v reference, or maybe an 2.048 or 4.096, but I have lots of doubts on how to make the analog front-end to drive the ADC, as it seems that a lot of secret sauce goes in there, for now I would like to only add one buffer/scalling stage to center the signal at Vref/2, and after watching some TI videos I dont know where do they get this equations:


Also if you know some nice app-notes about how to design such a front-end I would love to read them.

Best regards.

[MikeO]

Senso, look for docs written by Bob Pease.

Regards,
Mike O'

[robrenz]

Ditto for James M. Bryant

[senso]

Thanks for the names, I have been reading, but nothing really specific, or the specific app-notes are for transformer driven front-ends 
I will keep searching.

[senso]

After reading a lot of app-notes and datasheets, and some pretty nice AnalogZone documents from TI I have a better understanding on how all this SAR ADC's work and how to buffer their inputs, but I can't seen to find a nice rail-to-rail input and output op-amp that doens't have crippled Vin common mode voltages, they are all limited to 1 or 2v in the best cases, and usually only about 300mV differential inputs are allowed.
I will go the single ended route for now, it seems a bit easier and the trully diffferential op-amps are very limited in choice.
So I'm asking for some good to use op-amps.

And I would like to have a sanity check.
Based on this:


I can set my common mode voltage to 2.5v, and then use a 2.048v reference so I dont need to really hit the rails when driving the ADC, because even rail-to-rail op-amps dont have perfect drive capabilities near the rails.

[mrflibble]

Google "adc Bonnie Baker". Good app-notes + videos on delta-sigma ADC's.