According to one aspect, an ambient-light sensor includes a photodiode configured to generate an electrical signal according to an ambient light, a capacitive-feedback transimpedance amplifier connected at its input to the photodiode for receiving a signal generated by the photodiode and for generating as an output an amplified signal from the signal generated by the photodiode, and an auto-zero switch at the input of the capacitive-feedback transimpedance amplifier. The ambient-light sensor further includes a control circuit including a bootstrap circuit configured to receive an initial positive- or zero-voltage logic control signal, and then generate, from this initial logic control signal, an adapted logic control signal having a first positive voltage level and a second negative voltage control level for controlling the auto-zero switch.