Auto-zeroed charge transfer circuit

An auto-zeroed charge transfer circuit uses an output MOS transistor having a gate, a source and a drain; the gate of the MOS transistor being maintained to a predetermined control voltage and the drain of the MOS transistor being connected by default to a current sink; and a control circuit arranged to, in response to an input signal, bring the MOS transistor to a non-conductive state where any drop in voltage of the MOS transistor source causes the MOS transistor to conduct and, after connecting the drain of the MOS transistor away from the current sink and to an output node, pull down the source of the MOS transistor until a predetermined charge is sent to the output node through the MOS transistor.