Code transition error effects on estimation of nonlinearity and ENOB of an A/D converter

Abstract

Effects of error in code transition levels on nonlinearity and effective number of bits (ENOB) of an analog to digital converter (ADC) are presented in this article. Error in code transition level is determined by deviation of code transition levels from the mean of the estimated code transition levels. Errors in estimate of differential nonlinearity (DNL), integral nonlinearity (INL) and ENOB are computed by considering error in code transition levels and computing corresponding values. In this study, 5- and 8-bit ADC transfer characteristics are simulated and arbitrary nonlinearity errors are introduced. Suitable corrections are applied in code transition levels and computation of estimate of nonlinearity with and without corrections are reported. Results have been compared with earlier published work and improvements are observed. Effects of overdrive and additive noise on ENOB for 5-bit ADC are also reported.