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More Questions About the AD9161

I would still like the first set of questions I sent to you earlier to be answered but I have encountered a new set of questions I need answered in order to use the AD9161.

While I was connecting the AD9161 in my schematic and looking at AD916(2,4)-FMCC-EBZ RevC Schematic.pdf as a reference design guide, I realized there were a few things that are not really shown.

1.  What are pins F1, F2 and  J10, J9 really connected to?  I can not see that they are connected to anything in the schematic.

2.  I want to connect the differential outputs pins A7 and A6 to the I and Q differential inputs to the ADL5375 modulator.

How do you suggest I go about doing this?

3.  I am looking at the reference schematic and I am a little in the dark about the power up sequence of the AD9161 and the circuitry that does that.  Can you steer me in the right direction?

Thank you for answering ALL of my questions.

Randy Draper

RD Technologies

  • Hi Randy,

    On the ADL5375 side of things:

    To get a single-side band output, the inputs to ADL5375, I and Q, need to be quadrature in phase, that is, 90 degrees apart. Also, the baseband input bias levels for the ADL5375-05 is 500mV and for ADL5375-15 is 1500mV. Please note that the ADL5375 is ideally suited for zero/low IF -to-RF applications.

    In the ADL5375 datasheet page 24, there is a section on interfacing with DAC that provides a little insight.

    Thanks,

    HK.

  • Answers on the DAC side:

    1. Those pins connect to the FMC connector and are used in the SERDES link. Please refer to the SERDES section in the data sheet for more details.

    2. That is not how the part is used. To use the modulator, you need to use one DAC for I and one DAC for Q. What frequency are you trying to generate? The RF DAC can directly synthesize up to 6 GHz.

    3. Please refer to the data sheet's power supply section for details on power sequencing.

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