Patent ID: 7538710

Claim:
A device for measuring an electric charge in the form of a digitized value coded on N bits, comprising: a battery of N capacitors for integrating the charge, the capacitors having a common electrode intended to be linked to a current source providing the charge, each capacitor having an individual electrode, the values of the capacitances of the capacitors being in geometric progression, a capacitor corresponding to a bit Q of the digitized value; switches connected to each individual electrode operating according to two phases, an integration phase and a digitization phase; means for controlling the switches the said switches connecting the capacitors in parallel in the integration phase so as to integrate the charge in the capacitors wherein in the digitization phase each of the individual electrodes are placed in first and second distinct potentials, corresponding to the two logic states of the bit, so as to transfer or not transfer the charge carried by the capacitor to all the other capacitors of the battery; a logic unit for performing, in the digitization phase, N tests applied successively to each of the N capacitors of the battery, each test linking the individual electrode of the tested capacitor to the first potential, in comparing the potential reached by the common electrode with a defined potential (Vthresh), in defining the value of the bit Q corresponding to the capacitor tested as a function of the comparison result, then in linking the individual electrode to the second potential only if the bit Q is equal to a predefined value.