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AD9173 JESD Modes question and mapping I/Q Data to serial streams

Question asked by kassouf on Mar 20, 2018
Latest reply on Mar 23, 2018 by landsman

We are baselining the AD9173 for use in a comms. application.  I've read through the data sheet and I am still confused about the channel mapping.  We want to use both DAC cores with complex baseband / 24x interpolation.  DAC core 0 gets one complex baseband, and DAC core 1 gets a separate complex baseband, both are interpolated 24x and we need two separate RF outputs.  

 

We have an FPGA generating the JESD lanes, and we have 4 physical lanes going to the DAC.  We can figure out the data rate based on the equations in the data sheet, but the question is: Which JESD mode are we?  i.e. L=4 and M =2 because we are using 2 physical DAC cores or M=4 (because 2 complex sub channels per DAC)?

 

We can't seem to find the mapping between I/Q and the cores in the data sheet.

More research:

Configuration: We are using one channel (of the three listed per DAC) per DAC.  And we are using both DACs to provide two real RF outputs from two (separate) complex baseband input to each DAC.  I.e. each DAC core gets its own complex baseband. 

 

Based on the tables which describe lanes and data framing, using L=4 M=2 (mode 8) lane 0 contains upper bits of M0S0 and M0S1, lane 1 contains lower bits of M0S0 and M0S1.  Lane 2 and 3 contain the same data for M1.  Is M0S0 I data and M0S1 Q data for DAC 0 and M1S0 and M1S1 I and Q (respectively) for DAC1 or what?

—OR—

Do we have to use L=4 M=4 (Mode 4) and lane 0 contains I data for DAC0, Lane 1 contains Q data for DAC0, Lane 2 and 3 contain similarly I and Q data for DAC1?   So M0 is DAC0 I, M1 is DAC0 Q, M2 is DAC1 I, M3 is DAC1 Q?  I don't think this is the case because you can have up to 6 converters (3 channels per DAC) and they can each have a complex baseband and there is no mode where M=12 (6 channels x 2 b/c complex baseband).

 

 

Whatever the case, where in the data sheet does it outline how I and Q data are mapped to converters?

Sorry it's a long question, but I figure more information about our setup is better.

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