ywguo wrote on Feb 28th, 2007, 6:50pm:Hi, Guys,
I am studying oversampling converters. I want to know if the definition for oversampling converter specifications is different from that of nyquist converters. For eg., should we integrate the noise from DC to fs/2 or oversampling ratio × fs/2 on calculating SNDR?
BTW: What is the stopband attenuation?
Thanks
Yawei
Hi Yawei,
You are only interested in the bandwidth from 0 to fs/(2.OSR). The idea is that the stopband attenuation of the digital filter that follows
is high enough. This is anyway needed as your shaped noise power is quite high outside the signal band and rises rapidly after fs/(2.OSR).
Typically, the order of the digital filter needs to be 1 higher than the order of the delta-sigma modulator.
Regards
Vivek