Unified ADC nonlinearity error model for SAR ADC

The paper introduces a new ADC static nonlinearity model focusing on SAR ADC which is labelled the unified ADC nonlinearity error model. The model can also cover any other ADC architectures that have stochastic and/or periodic extremes in their integral nonlinearity function superposed on a “slowly changing” background. In the proposed model the function is decomposed into high and low code frequency components. Each component expresses a specific part of ADC nonlinearity error behaviour. The relations between the model order – the deepness of modelling and the model accuracy has been also studied by a simulation in the paper. The suggested model enables a simple estimation of ADC nonlinearity errors from fast ADC tests without the needs of the high accuracy of instrumentation required by the standardised test methods. The theoretical assumptions have been verified by performed experiments with two types of ADC, which confirmed the advantages of the proposed model.