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Ending the Debate Over Which A/D Converter is Best - Tom - 02-09-2021
Historically, the first and most important decision regarding Analog-to-Digital conversion was which topology to chose for your project. Anymore, unless you have a special case, the decision is easy. The Delta-Sigma (or Sigma-Delta, if you prefer) converter has swept the competition away for most applications.
It might seem normal that new technology would replace old, but the more usual case involves incremental improvements. Delta-Sigma is not only a radical departure, but also a dramatic improvement. The tradeoffs between speed and susceptibility to noise used to be the nub of the A/D debate. Delta-Sigma can be both faster, and quieter. Faster A/D converters tend to require higher power. More power means more self-heating, which leads to more temperature drift. Since even fast Delta Sigma converters tend towards low power, they win on that score, as well.
When you look back on a project and rate it compared to others, the tendency is to grade alternate techniques by ease of use. Delta-Sigma shines there, too. The noise rejection makes your signal conditioning look good, and the programmability allows you to optimize performance without redesigning the circuit board. Keeping a project on schedule helps with quality of life, and isn't bad for your career prospects, either.
The Types of A/D white paper has been updated. https://lawsonlabs.com/whitepapers/typesofAD.pdf
A quick review will provide perspective on how we got here, and just may enhance your appreciation for what Delta-Sigma converters have done to make the engineer's life easier.
Tom Lawson
February 2021