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AD4020 operation with single ended input gives non-zero reading even when inputs are not present ?

I'm using AD4020 for DC input measurement by implementing Figure 36 of AD4020 datasheet. Implemented schematic is below

But i'm getting non-zero readings which gives 0.25V reading by considering only MSB 15 bits and converting same to voltage by multiplying reading with 7.63uV. ie i'm getting readings like "7FB8x" as MSB. W.r.t to the schematic shared, what could be the problem, does this IC have some offset ? Please confirm single-ended DC input support for this part.

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  • Hi,

    Correct AD4020 is capable of measuring DC voltage input as well. The tool will show you on how to configure  ADC driver which ADA4940 in this case. To properly configure  the ADA4940 you can place 25ohms in series to R124 to gnd. I would also recommend to use the RC connected to your ADC input.