Proximity sensor systems and methods of operating same

A proximity sensor system comprising:

• a photo detector comprising a first doped region, a gate, a second doped region and a light absorbing region, wherein the light absorbing region includes at least one material in which, in response to light incident thereon, carrier pairs of opposite charge are generated, wherein the first doped region attracts a first carrier of the carrier pairs having a first charge, wherein the second doped region attracts a second carrier of the carrier pairs having a second opposite charge, and wherein the photo detector generates an output signal indicative of the presence of an object in a vicinity of the proximity sensor system;
• control circuitry for generating a plurality of control signals to be applied to the photo detector, wherein the plurality of control signals comprises a first control signal applied to the first doped region of the photo detector, a second control signal applied to the gate of the photo detector, and a third control signal applied to the second doped region of the photo detector;
• wherein the applied control signals control an operating state of the photo detector;
• and
• a signal detector to detect the output signal from the photo detector.