How does a delta sigma DAC work? - Page 3

phase_accurate · 4th June 2003, 11:35 AM

The intergrator is put between the feedback summing circuit (you may of course use a summing integrator as well) and the comparator.

For higher SNR you use multiple cascaded integrators.

Regards

Charles

ojg · 5th June 2003, 06:29 PM

This seems like a good thread to post my question in.

I have looked at the datasheets for the PCM1738 and the PCM1792, but they only show the frequency spectrum out to 100kHz. I can see the effect of noiseshaping, since the noisefloor increases after 20kHz and is then flat out to 100kHz.

I know that the spectrum repeats for each 8*fs (8*96=768kHz), but what happens between 100kHz and 768kHz? Is the noisefloor still flat or does it increase? Reason I would like to know is that it would affect the design of the post-dac filter.

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4th June 2003, 11:35 AM	#21
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	The intergrator is put between the feedback summing circuit (you may of course use a summing integrator as well) and the comparator. For higher SNR you use multiple cascaded integrators. Regards Charles

5th June 2003, 06:29 PM	#22
ojg diyAudio Member Join Date: May 2003 Location: Norway	This seems like a good thread to post my question in. I have looked at the datasheets for the PCM1738 and the PCM1792, but they only show the frequency spectrum out to 100kHz. I can see the effect of noiseshaping, since the noisefloor increases after 20kHz and is then flat out to 100kHz. I know that the spectrum repeats for each 8fs (896=768kHz), but what happens between 100kHz and 768kHz? Is the noisefloor still flat or does it increase? Reason I would like to know is that it would affect the design of the post-dac filter.

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