Development of circuit design of integration ADC




ADC, conversion equation, convergence conditions, geometric progression, absolute and relative conversion errors


An analysis of the ADC used in precision voltmeters Solartron models 7065, 7071 and 7081, which had record-breaking accuracy parameters for its time, was performed. The obtained transformation equations describing the process of formation of the output code based on the balance of charges on the integrator. It is shown that such a balance is difficult to achieve in all cases, because certain conditions are necessary for this. The main equations for determining the errors caused by the non-ideality of the ADC elements are derived. It is shown that the process of converting the input voltage into the output code occurs cyclically and has an iterative nature, that is, after the input voltage changes, the output code changes from cycle to cycle according to the law of geometric progression. The obtained expressions for the denominator of the geometric progression and the graph of the dependence of the denominator of the geometric progression on the input voltage, as well as the voltage oscillograms at the characteristic points of the circuit, are given. It is determined how the values of the denominator of the geometric progression affect the nature of the transformation process. The convergence of this process was investigated.


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