Hello,

   When we do the noise shaping, we need a DAC in the feedback loop and add the output of the DAC to the input of the sigma-delta modulator. Most of the time, we focus on the quantization noise in the ADC, but I wonder how about the noise from the DAC since its noise will be added to the input directly. Is it the same as the quantization noise or some other noise also become important.
   Thank you very much for your knowledge and sharing.

For SDM, DAC noise analysis is well studied in text books from Temes. Just read it.