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DAC38J84: 6 dB Mixer Gain is generating the Harmonics

Pavan
Intellectual 670 points
Part Number: DAC38J84

Hi

I am generating 600 MHz DAC output using NCO . I am enabling the Mixer with 0 dB gain. At the output I am able to see the 600 MHz Peak on the spectrum with Peak Amplitude of - 3 dBm

In my application, I need 0 dBm Gain. So I have enabled 6 dBm Mixer Gain. 

Gain increased to +1dBm, but I am having so many harmonics

How to remove all these Harmonics????  

In the datasheet, I have found some limitation for this

Can you explain in detail ???

  • 0
    TI__Guru* 91947 points

    Pavan,

    You are saturating the DAC. Try lowering the course gain.

    Regards,

    Jim

  • 0 in reply to jim s
    Intellectual 670 points

    Hi Jim

    To generate CW Signal, I am enabling Constant value and NCO 

    I am not using JESD Data.

    Config47 -- 0x2F -- 0x1

    config48  -- 0x30 -- 0x7FFF

    1. Config48 is 16 bit Register. But If I configure it as 0xFFFF, I am not getting any output. Why ??? How to check whether DAC is saturated or not??

    2. What I need to configure in config47 to achive max output gain without saturating the DAC?

  • 0 in reply to Pavan
    TI__Guru* 91947 points

    Pavan,

    Set 0x2 to 0x2050 to set the part in offset Binary mode, and mixer and NCO enabled.

    Set 0x2F to 0x5  for constant input.

    Set 0x30 to 0x00 for a constant input of 0.

    Se the NCO frequency, the DAC sample frequency, update the NCO values then Sync the registers.

    Regards,

    Jim