A Time-of-flight optical device and a 3D optical detector comprising a CMOS integrated circuit with an array of photosensitive pixels that are, at least in part, interconnected to form macro-pixels (180). Each macro-pixel (180) groups a plurality of individual pixels contributing their photocarriers to a common sense node SN through a plurality of transistors in parallel. Preferably the integrated circuit includes switched capacitor circuits arranged to combine the potential of the sense nodes SN of a plurality of macro-pixels, and/or to perform correlated double samplings in an energy efficient way. Each pixel has now an additional sink gate (194) between the pinned photodetector, PPD, potential well and a positive voltage source. By this additional sink gate (194), the storage well of the PPDs can be emptied without transferring the charge to the sense node. The value of the transfer gate voltage V_TG may be adapted such that the potential barrier is not lowered all the way down, but decreased to a value VB