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DAC3484: Output signal

SM
Expert 1760 points
Part Number: DAC3484


Hello,

    We are seeing a slightly lower signal level at the output of the DAC and also the harmonic levels and spurious are slightly higher. 

Following is our chain: 

There is a 3dB attenuator at the output which attenuates the signal. A full scale single tone is being sent to the DAC but the signal level is ~-8dBm instead of being > 2-3dBm (as per the plots in the datasheet). 

DAC configuration: Single tone of 15MHz being sent at 125MHz (interpolation in the DAC being set to 8x with the final DAC operating at 1GHz

There is a plot of the DAC operating in single tone mode (output @20MHz), the harmonics are below 70dBC but we in our case the spectrum looks as follows:

Please advise on how we could make the output power level correct and the harmonics reach the datasheet values. 

Thank you for your time in helping us out,

Regards,

SM

  • 0
    Expert 1760 points
    Hello,
    A few inputs that were missing from my earlier post:
    1) RBIAS is set to 1.28K (30mA (or max current))
    2) Gain is set for maximum in register 0x03 (0x0F is set)
    Regards,
    SM