when calculating the SNR of adc，should the bandwidth of noise be 1/2fsample？

[alex_fd]

when calculating the SNR of adc，if i want to calculate all the noise，should the bandwidth of noise be 1/2fsample？in the book，its said that the quantization noise of adc is distributed in the range from zero to 1/2fsample.and i have another question.when calculating the noise of a sigma delta adc from the output of its digital filter，should the integration bandwidth of noise be set to 0 to 1/2 of the clock frequency of the output digital code？

[pancho_hideboo]

when calculating the noise of a sigma delta adc from the output of its digital filter，
should the integration bandwidth of noise be set to 0 to 1/2 of the clock frequency of the output digital code？

No.
It should be effective bandwidth of digital filter which is less than 1/2 of the clock frequency.

[KlausST]

Hi,

many audio ADCs work with higher sampling rate, then they use digital filters, then they reduce the data rate.....
Thus 1/2 f more relates to the output data rate than to the true sampling rate.

--> I'd choose the bandwidth to the "typical bandwidth of interest of the ADC".

Klaus