• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 46 subscribers
  • Views 532 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DAC5688 NCO frequency setting

jeong jeong
Prodigy 20 points
Other Parts Discussed in Thread: DAC5688

I have questions about the DAC5688.

I using the DAC5688 chip as a DUC(Digital Up Converter).

DAC5688 input data are I, Q values. (IQ sampling)

And I using FMIX(Full Mixer) and NCO.

 

Question1) When the DAC input clock is 320 MHz (under external clock mode), maximum NCO frequency is limited up to (320/2) = 160 MHz ??

I want to generate the DAC output signal frequency of 200 MHz. If can, please advise me how to rising the DAC output signal frequency up to 200 MHz.

Question2) DAC5688 input data(I, Q values) rate is influencing to the DAC output signal frequency?

 

I hope your advice and warm answer.

Thank you very much ~!

Thanks.

 

Mr. Jeongslaa523a.pdf

  • 0
    TI__Mastermind 20541 points
    Hi Jeong,

    Yes you are right, maximum NCO frequency is half the DAC input clock rate. So with 320- MHz DAC clock frequency the maximum NCO frequency will be 160- MHz.
    The NCO can be used to shift the IF signal to higher frequency. So with the 320-MHz DAC CLK rate your maximum NCO frequency could be 160- MHz which means you could shift IF signal by 160-MHz.
    For example, an IF signal at 60-MHz can be shifted to 200 MHz by setting the NCO frequency to 140 MHz.

    If 320 MHz is not a system constrain, the best method would be increase the DAC sample rate so that 200 MHz signal is within first nyquist zone( DAC5688’s max sample rate is 800 MHz).

    Regards,
    Neeraj Gill
  • 0 in reply to Neeraj Gill
    Prodigy 20 points
    Thanks Neeraj Gill.
    I appreciate your warm and best answer.
    Thank you~!