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ADC12D1620QML-SP: Analog Input Offset Adjust

Gregory Duperon
Expert 7490 points
Part Number: ADC12D1620QML-SP

Is there an application note or guidance on how to use this feature?

Please clarify how/when this feature is used.

The plan is to use this device in dual channel non-DES mode w/AC coupled analog inputs.

A few questions:

  • Is this feature provided for DC coupled analog inputs? Is it applicable to an AC coupled analog input?
  • The default value for the I/Q offset registers is 0000h, which places the offset at 0V for both I/Q.  Are the data sheet parameters characterized with a 0V offset for I/Q channels?
  • There are some notes in Section 7.3.3. of the data sheet that imply that calibration minimizes the offset error. Is this related to the current value programmed in the register or something different?
  • Is there a recommended method for calibrating out the offset of the analog input? Should the analog input be terminated, noise loaded, or apply a narrow band signal?
  • 0
    TI__Mastermind 39310 points

    Hi Greg,

    See my comments to your questions:

    • Is this feature provided for DC coupled analog inputs? RR: typically, yes. Is it applicable to an AC coupled analog input? RR: yes, if the customer plans to interleave the two ADCs. This will help mitigate Fs/2-Fin spurious.
    • The default value for the I/Q offset registers is 0000h, which places the offset at 0V for both I/Q.  Are the data sheet parameters characterized with a 0V offset for I/Q channels? RR: the offset would be characterized so that the input common mode of the analog input is 1.25V+/-150mV per the datasheet specs.
    • There are some notes in Section 7.3.3. of the data sheet that imply that calibration minimizes the offset error. Is this related to the current value programmed in the register or something different? RR: yes, the current value.
    • Is there a recommended method for calibrating out the offset of the analog input? Should the analog input be terminated, noise loaded, or apply a narrow band signal? RR: it really depends on the application. Whichever the case, it would be best to calibrate over the temperature variance after the part has warmed up.