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Synchronization of AD9914

Question asked by SteBal on Feb 3, 2016
Latest reply on Feb 29, 2016 by JLKeip

Hi,

 

I am trying to synchronize two AD9914 DDSs. I have gone through all the available documentation on this topic (Multiple chip synchronization section of AD9915 Datasheet, Application Notes AN-1254, AN-605, AN-587, various discussion threads), and have followed the steps described in AN-1254 very carefully multiple times, but I have been unsuccessful at synchronizing the chips. I have a few questions:

 

1. I've been trying to do this using the evaluation board PC software that I downloaded from the Analog Devices website. Is it possible to achieve synchronization with this software, or do I need to use other kinds of external control on the DDS and/or parallel programming?

 

2. I cannot get the SYNC_CLK of the two devices to synchronize to each other and to the REF_CLK; either one or the other device is synchronized to the REF_CLK (and to the master device SYNC_CLK), but the devices are never synchronized to each other. AN-1254 says that "SYNC_CLK output is externally provided to synchronize to an external IO_UPDATE." I am not entirely sure what this means. I've been using the SYNC_CLK SMA outputs on the board to check for synchronization on the oscilloscope, and I've been manually applying I/O_UPDATE from the evaluation software. Am I doing this right?

 

3. The diagram in Figure 49 of the AD9915 datasheet shows the use of "Clock distribution and delay equalization" devices. Are these crucial to achieving synchronization? I've been trying to implement the schematic without them.

 

4. The evaluation software has an MCS (multiple chip synchronization) option under "Actions." However, nothing seems to happen when I click it. How does this feature help me synchronize the chips?

 

I appreciate any clarifications and/or further hints on how to achieve synchronization.

 

Thank you.

 

Best,

Stefania Balasiu

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