Active pixel circuit for a time-of-flight system and method for operating the same

A pixel circuit for performing Time of Flight measurements comprises at least one optical sensor arranged for receiving a reference modulation signal and a light signal and arranged for outputting a photocurrent signal depending on the light signal and on a phase shift corresponding to a phase difference between the light signal and the reference modulation signal, and an integrator circuit comprising an integration capacitor, an amplifier, and switching mean. The switching means is arranged for resetting the integration capacitor in a reset mode, for connecting the integration capacitor between the at least one optical sensor and a voltage reference signal in a passive mode. The negative feedback loop is fed with the photocurrent signal of the at least one optical sensor, and for connecting a signal output by the integrator circuit to an output bus in a readout mode.