polyam

Hi,
I've designed a deltasigma DAC. My reconstruction filter has a passband frequency of 10 MHz and a stopband frequency of 100MHz. My deltasigma is clocked at 800 MHz for an OSR of 128. So the BW is about 3MHz. Now the question is that in which bandwidth I should calculate the SNDR? 3MHz of fs/2=400MHz. If I calculate it over 3MHz I'll have SNDR=101 dB. If I calculate it over 400 MHz it will be 38 dB. Which one is correct?
tnx
