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Design >> Mixed-Signal Design >> Oversampling converter specifications
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Message started by ywguo on Feb 28^th, 2007, 6:50pm

Title: Oversampling converter specifications
Post by ywguo on Feb 28^th, 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

Title: Re: Oversampling converter specifications
Post by vivkr on Mar 1^st, 2007, 2:33am

ywguo wrote on Feb 28^th, 2007, 6:50pm:

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