[time-nuts] DDS'ery

Jim Lux jimlux at earthlink.net
Mon Jun 20 18:47:25 UTC 2011


On 6/20/11 7:46 AM, Luis Cupido wrote:
> Folks, a quick one...
>
> A DDS, that is an accumulator with a DAC followed by a low pass filter
> and comparator (zero crossing) to produce a square wave to drive a PLL
> or a MIXER or else (at logic levels).
>
> Isn't it the very same thing as just using the most significant bit of
> the accumulator.

The zero crossing using just the MSB will have jitter, compared to 
making a sign wave and then letting the zero crossing occur "between" 
samples.

Depending on your application, MSB only might work well enough.




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