C-language function class for signal processing at ADC testing

Testing of ADC’s differential nonlinearity DNL(k) by the histogram method requires the signal generator with extremely low distortion and high stability of the parameters. Besides this condition generator must be connected to the input of the ADC under test with high suppression of the interfering noise on ground line of instruments. The new type of testing signal has been proposed of the exponential form which could be generated by discharging of the capacitor across the resistance. The acquired digital samples from the output of ADC under test allow determining the best fitted exponential signal. The histogram from the registered samples and that for the best fitted exponential shape allows determining the differential nonlinearity DNL(k) for any code level k. Practical problems with generating the pure exponential shape are shown in this paper. The proposed method has been experimentally verified and was compared with the standardized methods.