When offset and gain errors are compensated for, the actual transfer function should be equal to the transfer function of perfect ADC. However, non-linearity in the ADC may cause the actual curve to deviate slightly from the perfect curve, even if the two curves are equal around 0 and at the point where the gain error was measured. There are two methods for measuring non-linearity, both described below. The figure below shows examples of both measures.
Figure 1. Example of a
Non-linear ADC Conversion Curve
