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Design >> Mixed-Signal Design >> SNR_max or Dynamic Range of Delta Sigma/Oversampling ADCs
https://designers-guide.org/forum/YaBB.pl?num=1389007658

Message started by harpoon on Jan 6^th, 2014, 3:27am

Title: SNR_max or Dynamic Range of Delta Sigma/Oversampling ADCs
Post by harpoon on Jan 6^th, 2014, 3:27am

Hi all,

I am getting confused with equations when going through this topic again.

Basically, for a Delta sigma modulator, the SNR_max (or Dynamic Range) is

10lg[(2^N-1)^2] +1.76+10lg[(2L+1)/pi^(2L)]+(2L+1)*10lg[OSR]

but for "Ideal Oversampling ADC with noise shaping", the SNR_max is

10lg[(2^N)^2] +1.76+10lg[(2L+1)/pi^(2L)]+(2L+1)*10lg[OSR]

i.e. the first term is higher for an ideal oversampling ADC with noise shaping ...

10lg[(2^N)^2] = 6.02N

and N= no of bits in quantizer, L=modulator order, OSR=oversampling ratio

Please see attached pic

Can someone clarify please ?

Thanks ...