[music-dsp] Oversampling to improve ADC precision?

[koen vos]

On Sun, 18 Jan 2004 19:51:35 +0100 (CET), "Pierre Richemond" wrote:
> 
> > From: "Augmentics" <musicdsp at augmentics.com>
> >
> >> Can running a 10-bit ADC at 16 x normal speed give you the
> >> equivalent of a 12-bit ADC?
> >
> > I don't know the numbers, but that is the basic idea of delta-sigma
> > conversion, so you might want to read up on that.
> 
> Yes, exactly. For the numbers, oversampling by a factor of two
> theoretically halves the power of quantization noise in the baseband,
> effectively gaining 3 dBs SNR, or 1/2 equivalent quantization bit.


Also, for this to work, you should increase the sampling rate but _not_ the
cut-off frequency of the anti-aliasing filter. This analog low-pass filter in
front of the ADC should thus cut off at 1/32 of your sampling frequency. 

You may have to add you own filter, in case the anti-aliasing filter provided
scales automatically with the sampling rate.

koen.