I am working on a redesign and there is a negative bias generator on the ADC in the circuit. (not the circuit below) I am pretty sure that the small negative voltage instead of ground is there to ensure readings are correct when the input to the ADC is close to zero (or ground) but I am not sure I fully understand. Can someone explain the purpose of the negative bias generator more clearly? Also will the negative reference on the ground pin affect anything else in the circuit? For example do I need to compensate for the offset at the output at all?
NOTE: The circuit below is not the circuit I am working on. just an example that I found using the negative bias.