DNL ADC testing by the exponential shaped voltage

Testing of ADC differential nonlinearity by the histogram method requires a signal generator with extremely low distortion and high stability. In this paper, the new type of stimulus signal is proposed, which simplifies the task. The testing signal has an exponential form and can be generated simply by discharging the capacitor across the resistance. The resulting digital samples from the output of the tested ADC allow estimation of the best fitted exponential signal by the proper three-parameter method. The histograms from the data record and from the best fitted exponential approximation allow calculation of the differential nonlinearity.