Differences between audio ADCs and general-purpose ADCs

Question

From my limited understanding, audio ADCs, and even decoders, also have 16-24 bit resolution and not-so-low sample rates in comparison to high-resolution, low-noise ADCs.

It's also worth noting that the two have different metrics to focus on. As far as I know, audio ADCs tend to have worse low frequency noise performance, worse temperature drift, and focus on dynamic range, linearity, and noise performance in the white noise band.

The manufacturers' differentiated labelling in the datasheets has caused some problems for me as a beginner. My main questions are as follows:

A more complete understanding of the similarities and differences between audio ADCs and general purpose ADCs.

Do multichannel audio ADCs have to be synchronously sampled? Even though I can't find the relevant words in the datasheet.

For certain scenarios, such as using an audio ADC to convert amplified bioelectric signals (usually low frequency signals within 0.1Hz-100Hz), Is this feasible?

Thanks for reading my question. I am looking forward to receiving your advice.

Answer 1

Audio ADCs may have properties that make them unsuitable for some other purposes.

For example they might have a minimum sampling rate and it might be as low as 8 kHz but it might be 32 kHz, which is a bit excessive for sampling e.g. 100 Hz bioelectric signals.

Audio ADCs may have digital filters to remove DC and it may limit the ability to sample low frequencies like 0.1 Hz.

Audio ADCs have interfaces to output a digital audio stream such as I2S or TDM or DSD. It will force your system to receive data as digital I2S/TDM/DSD audio stream.

Audio ADCs are not guaranteed to sample simultaneously. But on the other hand, they might use oversampling sigma-delta ADCs so it might not be a huge difference if the signals are sampled at a few MHz.

So if you want to use an audio ADC then a lot of audio specific baggage comes with it. You might want lower sampling rates, bandwidth maybe even down to DC so you can remove DC offset yourself, guaranteed simultaneous sampling and some more sensible digital interface like SPI for your application.