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ADS127L11: DC performance

Part Number: ADS127L11


I would like you to confirm whether there is difference about DC performance such as drift(offset, gain) and error(offset, gain) b/w full differential input and pseudo differential input.
In my understanding, in general, SNR and THD may affect impact depending on input setting, however there is no difference for DC performance.
However, if my understanding is incorrect, could you please give me advice about this ?


  • Hello Machida-san,

    Yes, you can expect drift(offset, gain) and error(offset, gain) to be similar between pseudo-diff and fully-diff modes.  SNR and THD will degrade using pseudo-diff verses fully diff, but performance will still be very good in pseudo-diff mode.

    There will be an additional DC error to consider when using pseudo-diff mode; CMRR.  Assuming Vref=2.5V, AINN=2.5V, and AINP range of 0V to 5V, you will see a shift in common mode voltage of 2.5V over the full scale input range.  With a minimum CMRR=110dB, this will result in an additional worst case error of 8µV, and a typical CMRR=130dB, a typical additional error of 0.8µV.

    Keith Nicholas
    Precision ADC Applications

  • Hello Nicholas-san,

    Thank you for your reply.
    For CMRR, since we will use AINN=0V w/ AINP +/-2.048V, so I believe we just need to consider offset voltage at ground level as additonal error.


  • Hello Machida-san,

    O.K., I assume your supply voltages will be AVDD=+2.5V and AVSS=-2.5V to support +/-2.048V on the AINP input.

    Yes, since your input range will be +/-2.048V, the maximum common mode that the differential input sees will be +/-1.024V.  In this case, the typical CMRR error will be ±0.32µV (CMRR=130dB) and the worst case error will be ±3.2µV (CMRR=110dB)