Differential nonlinearity is a characteristic value of A/D converters that describes the maximum errors of the quantization stages. Ideally, all quantization stages have the same time intervals.
The deviation of the quantization stages from the ideal is called differential nonlinearity (DNL). The DNL value specifies the positive or negative deviation from the ideal width for each individual quantization stage as the number of least significant bits ( LSB). Where 1 LSB corresponds to the ideal width. With error-free quantization steps, the step transition thus corresponds to 1 LSB and there is a staircase-like increase in the threshold voltage, with each step having the same step width.
The differential nonlinearity corresponds to the step deviation from the ideal and results in the analog input signal being sampled slightly earlier or later than after 1 LSB. The sum of the DNL values corresponds to the integral nonlinearity. The differential nonlinearity DNL (i) gives for each stage i the positive or negative deviation from the ideal width in units of LSB (Least Significant Bit); 1 LSB corresponds to the ideal width. By summing up the DNL (i) over all stages up to stage k, the integral nonlinearityINL (k) is obtained.