An optical proximity sensor comprising a solid-state photo-electric converter, a biasing circuit for biasing the solid-state photo-electric converter, and a drive circuit, wherein the solid-state photo-electric converter comprises at least one of: an array of single photon avalanche diodes, an array of avalanche photodiodes, and a silicon photomultiplier, and wherein the drive circuit is configured to: control the biasing circuit to apply to the solid-state photo-electric converter a bias signal modulated between a first value and a second value, the second value different from the first value, wherein said first value of the bias signal is higher than a breakdown voltage of the solid-state photo-electric converter, and wherein a modulated optical signal is emitted by the solid-state photo-electric converter towards a target object, receive an electrical output signal from the solid-state photo-electric converter, the electrical output signal being a function of a modulated optical signal received at the solid-state photo-electric converter as a result of reflection of said emitted modulated optical signal at said target object, perform a phase comparison of said modulated bias signal applied to the photo-electric converter against said electrical output signal received from the solid-state photo-electric converter and produce, as a result of said phase comparison, a phase shift signal which is a function of the phase shift between said modulated optical signal emitted by the solid-state photo-electric converter and the modulated optical signal received at the solid-state photo-electric converter, and compute a distance between the optical proximity sensor and said target object as a function of said phase shift signal. an array of single photon avalanche diodes, an array of avalanche photodiodes, and a silicon photomultiplier, and wherein the drive circuit is configured to: control the biasing circuit to apply to the solid-state photo-electric converter a bias signal modulated between a first value and a second value, the second value different from the first value, wherein said first value of the bias signal is higher than a breakdown voltage of the solid-state photo-electric converter, and wherein a modulated optical signal is emitted by the solid-state photo-electric converter towards a target object, receive an electrical output signal from the solid-state photo-electric converter, the electrical output signal being a function of a modulated optical signal received at the solid-state photo-electric converter as a result of reflection of said emitted modulated optical signal at said target object, perform a phase comparison of said modulated bias signal applied to the photo-electric converter against said electrical output signal received from the solid-state photo-electric converter and produce, as a result of said phase comparison, a phase shift signal which is a function of the phase shift between said modulated optical signal emitted by the solid-state photo-electric converter and the modulated optical signal received at the solid-state photo-electric converter, and compute a distance between the optical proximity sensor and said target object as a function of said phase shift signal. control the biasing circuit to apply to the solid-state photo-electric converter a bias signal modulated between a first value and a second value, the second value different from the first value, wherein said first value of the bias signal is higher than a breakdown voltage of the solid-state photo-electric converter, and wherein a modulated optical signal is emitted by the solid-state photo-electric converter towards a target object, receive an electrical output signal from the solid-state photo-electric converter, the electrical output signal being a function of a modulated optical signal received at the solid-state photo-electric converter as a result of reflection of said emitted modulated optical signal at said target object, perform a phase comparison of said modulated bias signal applied to the photo-electric converter against said electrical output signal received from the solid-state photo-electric converter and produce, as a result of said phase comparison, a phase shift signal which is a function of the phase shift between said modulated optical signal emitted by the solid-state photo-electric converter and the modulated optical signal received at the solid-state photo-electric converter, and compute a distance between the optical proximity sensor and said target object as a function of said phase shift signal.