Hello!!!
I have very stupid question :-) about understanding - what is gain error, that write in datasheets for differential-input delta-sigma ADSs (such as ADS1118 and etc.). In you terminology:
http://www.ti.com/lit/an/slaa587/slaa587.pdf
2.2.Gain Error
Gain error is:
1 - difference for full scale range
2 - difference for gain slope
For unipolar ADCs this two terms is same. But for bipolar ADCs this is same for case, if treat "full scale range" term as 1/2 of bipolar range.
I treat that +-2048mV bipolar range is 2048mV full scale range, and calculate 0.15% Gain Error is 2048 * 0.0015 = 3mV error when measure low(-2048mV) and high(+2048mV) input signals.
This is right???
Or i must use 4096mV full scale range for calculate gain errors from datasheet values???