AD9912: Sync multiple devices

Document created by analog-archivist Employee on Feb 23, 2016
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Synchronizing Multiple AD9912 DDS devices. I am looking at an application with
multiple DDS devices working together. Though the AD9910 enables this feature I
prefer working with the AD9912 because of it's: Lower power dissipation
Internal acumulator size, It's better SFDR Spur rejection. Question: Can I
guarantee multiple AD9912 synchronization by using a synchronized reset or any
other technique ?


Unfortunately, the AD9912 does not have any provisions (or built-in circuitry
like the AD9910) for synchronizing multiple parts easily.
In addition, there's no access to the internal DDS clock (system clock /4).
Therefore, the DDS clock could be in one of four phase relationships
across multiple parts (0 , 90, 180, 270). The phase of the DDS clock would be
random at power up across parts but should stay fixed unless powered down.
Without the DDS clock align data into the part with go in with a timing
uncertainty of System clock / 4. Can they live with this timing uncertainty??
This want be easy, if not. You'll need some external circuitry involved to
first check the output for synchronization and then randomly power parts on/off
until they appear synchronized.