[time-nuts] SI532X Chips Close In Spurs (Somewhat Long)
hmurray at megapathdsl.net
Tue Jan 9 01:37:47 EST 2018
marklgoldberg at gmail.com said:
> I was hoping someone who knows these devices might have some insight into
> what the issue is and how to determine which plans will not provide close in
> spurs, without requiring testing. Any suggestions are appreciated.
If you look at the binary of the word that goes into a DDS adder, the ones
with more low order bits have closer in spurs. Think of that word as a
fraction, binary point on the left rather than right.
If your adder word is 0.001 (binary) it will divide by 8, no spurs.
If you have 0.00100001, it will divide by a little less than 8 and have spurs.
These are my opinions. I hate spam.
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