Electric quantity measuring device comprising an analog-digital converter

It is described an electronic device (1) for measuring an electric quantity, comprising: an analog- digital conversion module (2) configured to digitally convert time portions of an analog signal (S M (t)) to be measured alternated with time portions of a reference analog signal (S R (t)), for supplying respective first (DSM) and second pluralities (DR) of digital values and a digital processing module (3) configured to: calculate a first mean amplitude (A1) of the first pluralities of digital values, and a second mean amplitude (A2) of the second pluralities of digital values; the first and second mean amplitudes being proportional to a mean gain value of the analog-digital conversion module (2); supply a ratio value (VRT) of the first mean amplitude to the second mean amplitude, representative of a measured amplitude of the analog signal (S M (t)) to be measured.