Analytical a priori approach to phase-plane modeling of SAR A/D converters

Abstract

An analytical a priori approach to error modeling of successive approximation analog-to-digital converters (ADCs) is proposed. Errors are modeled as a function of both the output code and the time slope of the input signal. In particular, errors intrinsic to the algorithm of successive approximation in case of input signal time variation less than the least significant bit (LSB) during conversion are considered. The resulting differential nonlinearity is analytically related to the bit composition of the ADC output code bin. Analysis of errors intrinsic to the conversion algorithm makes the model general and application-independent. Moreover, the a priori approach makes its accurate identification easier. Numerical and experimental results of the model validation showing the effectiveness of the proposed approach are discussed.