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DAC38J84 Evaluation Module DC offset

Alexander Lozhkin
Prodigy 100 points

I modified DAC evaluation board, thus now DAC outputs are connected directly to 25-ohm resistors. The problem is some DC offset. Actually when I send DAC code as 0 (zero) the actual voltage in the DAC output is 50 mV. My question: is there some possibilities to adjust this offset to zero? Thank you for support.


  • 0
    TI__Guru* 78744 points

    Alexander,

    You may want to see if the QMC offset feature can work for your application. The QMC offset is meant to trim LO feedthrough of the modulator output by adjusting minor DC offsets at the DAC output to the modulator baseband input. The offset range is very small though, only 12bit range of DC code and may not be sufficient to 50mV offset adjustment. 

    -Kang

  • 0 in reply to Kang Hsia
    Prodigy 100 points
    Hello Kang and thank you for the suggestion. In my understanding, this is not actually DC offset as it is. This is something like the common DC in DAC outputs. It can be remove easily with balun or differential amplifier. However, I’d like to avoid such output stages in my design. So I am interesting in DAC with the resistive (25 ohm) load only.
    Anyway, thanx for reply.
    Alex.