| There's self-dithering on initial A to D conversion, and there's dithering during processing or delivery when reducing wordlength. Even if there is enough noise of the right kind to self-dither at the ADC, this doesn't exempt you from needing dither for subsequent wordlength reductions to prevent truncation distortion and loss of subjective resolution below the LSB (Least Significant Bit).
However, re: AD conversion, even with the noise present during conversion, there's no way to guarantee that there will be a sufficient amount of the right kind of noise, particularly a high frequencies, to ensure complete de-correlation, and the benefits resulting from proper dithering. |