digital filter for sigma delta modulator

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symphonics

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Good day everyone,

I am Patrick. I am an undergraduate student taking my thesis. My group's topic is about the 2nd order sigma delta modulator. My task for this group is to design the digital filter.As far as I know, The purpose of the digital filter is to remove the quantization noise that has been pushed to the higher frequency.Thus, improving SNR and thus,improving the resolution.

Our specification:
input frequency:10kHz
oversampling ratio: 128
sampling frequency:2.560Mhz

My question:
1) Given that the low pass filter to be used to remove is not ideal. How do I determine the new SNR.
2) In designing a low pass filter, There are five parameters to be considered. The passband gain , cutoff frequency,stopband frequency,stopband attenuation and the order of the filter. How does this parameters relate to the number of bits/resolution of the system.

Basically,The purpose is to find the overall specification of the filter to be used in the 2nd order sigma delta modulator.

Regards,
Patrick
 

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