Fourier analysis and synthesis for a Mildly Non-linear Quantizer

We introduce and analyze a method for stabilizing test parameters and estim ating the non-linearity of mildly non-linear quantizers by Fourier analysis of the quantizer's output to sinusoidal input signals. Stabilization for t he combined effects of the rounding operation of the quantizer and the vari ations in offset and amplitude of the applied sinusoid is achieved by a det erministic form of subtractive dithering, called wobbling. It thus appears that one can retrieve low-to-medium degree non-linearities whose contributi on to the quantizer's distortion in the relevant frequency range is of the same order as or well below the distortion due to rounding before wobbling. For the analysis of the method a thorough investigation of the spectra of sampled, quantized sinusoids (wobbled or not) has to be made. As such we co mplete and extend existing results in the literature of spectra of this typ e. The method is potentially useful for estimating the integral non-lineari ty of AD-converters. (C) 2000 Elsevier Science B.V. All rights reserved.