Application of deterministic dither signals in digital voltmeter with sigma-delta oversampled A/D converter

An essential disadvantage in application of the oversampling A/D converters in high-accuracy DC digital voltmeters are local peaks of quantization errors observed for some specific input signal values. Those peaks, connected with appearance of the specific sequences of output signals, called "correlation codes", considerably lowers effective resolution of the converters for particular values of stationary input signals. Methods of reduction of those peaks of errors by means of deterministic, self-subtractive dither signals, used in high-resolution digital voltmeter, build with a standard, commercially available sigma-delta converter are described in the paper.