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AR# 17048

LogiCORE DDC v1.0 - Which outputs of the DDS/mixer subsystem are associated with the I and Q channels of the DDC Core?


The DDC Core when implemented has the sine output of the DDS connected to the I channel, and the cosine output connected to the Q channel.

This is not explained in the documentation.


This may be counter-intuitive to people who are using the core. Often, the cosine is assumed to be associated with the I channel, sine with the Q channel.

For certain applications, it is important to be aware which way the core is connected.

The work-around for designs that require these connections reversed is simply to connect the I channel coming out of the DDC Core to the Q channel in the rest of the design, and similarly the Q channel to the I portion of the design. The filters and remaining paths after the mixer in the DDC Core will be identical.

AR# 17048
Date Created 09/03/2007
Last Updated 12/15/2012
Status Active
Type General Article