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DAC37J82: DAC37J82

user4959713
Prodigy 35 points

Part Number: DAC37J82

Hello, I want to realize up-conversion  from 25MHz to 75MHz using DAC37J82 . The following is my configuration parameters in DAC3XJ8X GUI v1.1:  100MSPS input data rates, 4x serdes lanes, 4 interpolation,  400MSPS output data rates. When i use coarse mixer by selecting fs/8 in Dig Block1 tab, i can get my expection result 75MHz by observing spectrum analyer.  When i use NCO FMIX by setting AB frequencty 50MHz, i find the result is 50MHz, 100MHz, 150MHz displaying on spectrum analyer. During this two ways, all the others parameters is same(fault). I want to know how can i realize up-conversion through FMIX from 25MHz to 75MHz

  • 0
    TI__Genius 12965 points
    Hi,

    Can you send a screen shot of the GUI/ Dig Block 1 settings?

    The NCO should work fine. The issue we typically see is if the output sample rate is not set correctly to the output rate of the DAC (in this case 400Msps). This will not scale the frequency register correctly and will possibly program the wrong register values for the NCO mixer.

    Also, you will need to toggle SIF Sync to make the NCO registers take effect.

    Ken.
  • 0 in reply to Ken C
    Prodigy 35 points
    Hi,
    Ken, I find that i don't know how to send a shot of the GUI/ Dig Block 1 settings here, can you give me you e-mail address, i will send you my shot on e-mail, think you! Hope to make friends with you!
  • 0 in reply to user4959713
    TI__Guru* 91947 points

    DAC37J82_DAC_NCO_demo.pptxDAC37J82_NCO_50MHz_reg_settings.csvuser4,

    If you are using the TI DAC EVM with a TSW14J56EVM, you can follow the attached slide show to get this setup up and running. If this is a custom board, I have also loaded the register settings used by the DAC and LMK devices on the DAC37J82EVM for this setup. With the NCO at 50MHz and the input data at 1KHz, you will see a tone at 50MHz, 350MHz, 450MHz, ect...

    Regards,

    Jim