>Hi all,
>
>[snip]
>
>Besides the obvious things of having a stable, clean power
>supply with decoupling, good ground plane, short interconnects, and
>low-pass-filtering the ADC input to limit noise and alaising, what else do
>I have to watch out for? Can anyone give me any pointers or app notes to
>look at?
>
>A temperature-compensated voltage reference. The worst-case performance
>is generally limited by the tempco of your voltage reference.
>
>For example, take the LM329B. It has a tempco of 20ppm per degree C.
>Lets say the temperature range is 0-70. that gives you a max 45 C swing
>(the specs are given at 25C). the total error due to temperature alone is
>900ppm. That's good enough for 8 bits, but not much more.
>
>Going to the 399A gives you a tempco of 1ppm/C. For the same temperature
>range, the error is reduced to 45ppm. Plus long-term stability of 20ppm,
>and a load regulation of 26ppm, and we are ove 80ppm already. I guess
>you might be able to use that for 11 or 12 bits (but don't forget to take
>other errors into account).
>
>As for pointers, I guess a good place to start looking would be data sheets
>on voltage references (actively trimmed, temperature compensated, etc).
>
>I'm not familiar with high-performance A/D converters. Perhaps one of the
>better 16-bit versions would have such a reference included?
>
>Phil Eisermann
>H:(440) 284-3787 (mazer@ix.netcom.com)
>O:(440) 329-4680 (peiserma@ridgid.com)
>
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