Incremental delta-sigma ADC dynamic range

[electronics_rama]

Hi,

I am referring to a paper for the optimum filtering which can be used for the incremental delta-sigma ADC. I came across a below point and below is the diagram stating that for a given sigma-delta modulator loop, we can achieve higher and higher dynamic range by using higher and higher order filters. M is the OSR in the below diagram. Col1 is the first order filter. Col2 is the second order filter. By using Col2, the dynamic range is extended by 24dB. If this is true, why do we have to go for higher order delta sigma modulator? We can use a first-order modulator and higher-order filter to achieve a high-resolution ADC. Can anyone explain this?

Thanks

 

[FvM]

Your considerations are right if the application can use high OSR of 100 and more. But applications with higher data rate are often limited to OSR of 8 or 16. Higher order modulator is required to achieve acceptable SNR then.

 

[electronics_rama]

Your considerations are right if the application can use high OSR of 100 and more. But applications with higher data rate are often limited to OSR of 8 or 16. Higher order modulator is required to achieve acceptable SNR then.

I did not get your point. What do you mean by data rate here?

 

[KlausST]

Hi,

sampling_rate / OSR = data_rate

Please review delta sigma ADC operation theory.

Klaus