mixed_signal wrote on Jan 29th, 2012, 8:46am:If I use sigma delta and chopper circuits to minimise the offsets (for uncalibrated inaccuracy) then the power increase. One good thing is that my sensing range is small -20 to 30C and I have a low sampling rate of 1 sample per minute.
A Delta-Sigma or incremental is going to use FAR less power than a dual slope and more robust. As Jerry said, nobody uses dual slopes anymore. I doubt if you could even meet 10x that power with a dual slope -- MAYBE if you use an external capacitor, and you can't get away with a cheap capacitor on a dual slope.
I mentioned an incremental ADC. If you are continuously sampling the same input a delta-sigma is fine too, except every once it will give you an answer 1lsb different. With an single order incremental the decode is just a counter and you have so much time that you could get 16 bits with a 1kHz clock.
These are the types of circuits I love to design
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Do some searching on google scholar. It wouldn't surprise me if there is a published sensor design to meet your needs.