rakesh045
Newbie level 6
i am designing a sigma delta ADC. I have completed a second order modulator. My frequency range is upto 40MHz oversampling. My required resolution is 12 bits and so i oversample by 64 times in a second order sigma delta modulator
My question is with the operation of filters... I heard that sinc3 filter and cic filters are best in doing the role of digital decimation filter. Which among the two is best for my specifications?
Also i have a general doubt regarding the output...
The sigma delta modulator gives a 1 bit stream output and the number of 1's will increase if there is a positive slope in the analog waveform and lot of 0's if there is a negative slope irrespective of the position(current analog signals voltage value) in the waveform.
Norma ADC's provide bit stream that directly corresponds to the position (current analog signals voltage value) of the analog signal irrespective of the slope.
How does the decimation filter change this slope indicating sigma delta output to that of a signed magnitude of signed complement form?
My question is with the operation of filters... I heard that sinc3 filter and cic filters are best in doing the role of digital decimation filter. Which among the two is best for my specifications?
Also i have a general doubt regarding the output...
The sigma delta modulator gives a 1 bit stream output and the number of 1's will increase if there is a positive slope in the analog waveform and lot of 0's if there is a negative slope irrespective of the position(current analog signals voltage value) in the waveform.
Norma ADC's provide bit stream that directly corresponds to the position (current analog signals voltage value) of the analog signal irrespective of the slope.
How does the decimation filter change this slope indicating sigma delta output to that of a signed magnitude of signed complement form?