Features of Modeling of Analog-to-Digital Converter Transfer Function by Simulink

Abstract

Analog-to-digital converters (ADC) are the most commonly used converters at measuring and control devices. The transfer function of a real ADC is different from the ideal one. There are additive, multiplicative and nonlinear components of the error. The number of bits of any ADC is finite, which results to the appearance of quantization error. Due to the presence of aperture delay and aperture jitter, there is a variable in time delay of sampling of the input signal. In case of measuring the integral parameters of the signal (root mean square value, active power, reactive power, apparent power, etc.), the evaluation of the impact of the ADC nonidealities at an analytical form is a difficult task. This is especially true in the case of nonlinearity and quantization error. For this reason, it is of interest to estimate the measurement error by performing simulation mathematical modeling. The problem under consideration is also relevant in the educational process for all areas related to measurement technology, where the simulation is actually the only opportunity in a limited academic semester time to assess the impact of these nonidealities of ADC measurement error of the considered parameter. Build of the ADC effective model can be done using Simulink. The article describes the sources of the ADC nonideality and approaches for their modeling by Simulink. The features of the modeling of ADC nonlinearity of successive approximation and Sigma-Delta ADC architectures. The model of the ADC, taking into account all these parameters.