Computer Study of Quantizer Output Spectra

Abstract

This article describes a method for accurately calculating the output spectrum of a quantizer. The method was developed for known expressions defining the output spectrum of an arbitrary quantizer with gaussian input of arbitrary bandshape. Results obtained for a variety of conditions, however, suggest that the calculations are valid even though the input has only a minor gaussian component. When sampling is also used, at the Nyquist rate or a little higher, the quantizing noise folded into the input band is almost flat even when the input bandshape is sharply peaked. When interference at the input is increased, the quantizer (preceded by AGC) appears to operate like an increasingly noisy linear transducer up to a breaking point beyond which its performance (for small signals) degrades rapidly and becomes difficult to analyze.