Analog-to-digital conversion and harmonic noises due to the integral nonlinearity

Analog-to-digital conversion inherently introduces unwanted harmonic noises due to the nonlinear transfer function error. It is essential to set proper models of the noise generation mechanisms, to quantify and compare the analytic performance of the high-resolution measurement systems including analog-to-digital converter (ADC). We addressed the importance of the integral nonlinearity in the analysis of the ADC system. We modeled the nonlinearity via a linear combination of simple power functions with single parameters and calculated the magnitudes of the harmonic noises generated by the sigmoidal shape of the ADC transfer function, analytically and numerically. For a typical ADC, a model x^(1+ν)+μx² was reasonably adopted, which produced the most significant harmonic noises at the second-and the third-order multiples of the fundamental frequency. Practical examples of the high-resolution ADC were observed, and demonstrated to show that the simple model explains the harmonic noises