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In Reply to: RE: Looking for serious reading material posted by Tony Lauck on March 18, 2014 at 07:20:14
Howdy
Chase down the patents... I used to work with John Melanson before he went to Cirrus Logic. I think some of his patents might have the kind of detail you are interested in. I noticed that he has more than 100 of them, but looking for DDS and/or sigma delta might narrow them down.
When I tested them next to a high quality crystal they fared fairly well. I suspect that since their jitter error is fairly white that their errors aren't as audible as they might appear from the numbers. I'd use them in a lower cost DAC.
-Ted
Follow Ups:
I'll have to look some more details on DDS circuitry. The patent that I read was mostly about the complete system and didn't contain much information on the specific DDS circuit. What it said pretty much matched my model of how such a device might work, except for some additional detail of the DS DAC used to generate the quadrature synthesized waveforms. (Which I didn't understand, in that no one really understands DS modulators, or at least if they do they aren't talking... )
Thanks for your help. Incidentally, I would be curious to see how your DAC sounds when playing PCM files converted in the computer to DSD128 by various programs such as HQPlayer, vs. how the same files sound when the native PCM is converted by your FPGA. Perhaps some of the reviewers can conduct these listening tests.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Thanks. It looks like US 7,557,661 is probably the one. Printing it out now.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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