The thesis addresses development of integrating AD-converter, with goal uncertainty of 10^-6. Based on detailed study of weaknesses and advantages of existing solutions we extract the key sources of uncertainty. In the central part of this thesis we propose a novel solution, that inherently reduces the influence of this uncertainties. The main idea of our proposal is that by thorough self calibration the uncertainty of the reading of the instrument depends solely on the uncertainty of the reference voltage. For the purpose of calibration we introduce auxiliary AD converter, which measured uncertainty turned out to be in the range of uncertainty of the reference instrument. Achieved measurement uncertainty of the whole instrument including main AD converter is (4,2 +/- 2,26)*10^-6.
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