I am trying to understand the audio signal chain and got a bit stuck on ADCs... I am trying to figure out what the digital representation looks like in terms of voltage/current in the wire after the sampling and quantization process. I made a quick illustration in paint (below) and am wondering if the digital output looks like A or B. The only reason I'm confused is because I watched a lot of YouTube videos and some used graphs that look like A while others B. The Y-axis of course represents voltage (the bit values are just there as a quantization/range reference)


  • 1
    As you show them here, they are actually the same thing. The output is a string of numbers, 0 to 7, and you might want to transfer them either way. Some AD converters has, in this case 3, data signals as in A. Some AD send them serially over one line as in B. Functionally they are equivalent.
    – ghellquist
    Commented Sep 21, 2020 at 21:37

1 Answer 1


The actual signal on the output of an AD converter looks more like B.

  • A looks like a parallel link: the 3 bits are sent at the same time via different, parallel paths. A can also be used as a more symbolic interpretation: instead of showing the output bit by bit, it shows the output sample by sample.

  • B is a serial link: the bits are sent one after the other via the same path.

Digital audio is mostly serial in nature: bits on a CD are written in series, digital audio links are serial. AD converters have a serial output.

A looks a bit like the output from a DAC: a series of voltage steps that have to be smoothed out into a sine wave.

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