MODELLING OF INSTRUMENTATION SIGMA-DELTA ANALOG-TO-DIGITAL CONVERTERS

摘要

The paper examines a behavioral model of sigma-delta analog-to-digital converters (SDADC) which allows the uncertainty of A/D conversion to be evaluated. The most sources of the uncertainty are represented in data sheets of modern SDADC. However, information given by manufacturers now is not enough to evaluate the conversion uncertainty with given probability. The most critical situation takes place for noise of SDADC - the major source of the uncertainty in many cases. This problem is mainly discussed in the paper. Conditions for evaluation of the conversion uncertainty with given probability are found from theoretical analysis, simulation of a typical SDADC electronic model and experimental data. Some propositions for including corresponding parameters and tests into standards are made.