Development of a Sigma-T Analog-to-Digital Converter in NI Multisim and Research of Dielectric Absorption of the Integrating Capacitor

All modern precision analog-to-digital converters (ADCs) for voltage conversion use the integrating method as an intermediate conversion. In implementing this method, the linearity of the conversion function can be influenced by the dielectric absorption of the integrating capacitor. The task of investigating its impact on the conversion accuracy of precision integrating ADCs, which sum the results of the conversions of adjacent partial cycles, is quite relevant for ADCs of the Σ-architecture, where fundamentally there is an error due to the desynchronization caused by mismatched completion times of the partial and full conversion cycles. The objective of the research is to develop a new class of integrating ADCs with intermediate integrating voltage conversion into a pulse-width-modulated signal, which sums the results of the conversions of partial cycles (ΣT-ADCs), and to study the influence of the dielectric absorption of the integrating capacitor and the number of partial conversion cycles on accuracy through simulation modeling. A computer model has been developed in NI Multisim. Experimental research has been conducted, and the values of the standard deviation of the linearity of the ADC conversion function have been obtained, without taking into account the dielectric absorption of the integrating capacitor, as well as with the addition of the equivalent circuit of the integrating capacitor to the model with a series of absorption coefficient values - 0.01; 0.03; 0.05; 0.07; 0.1.