A 640×480 Indirect Time-of-Flight Image Sensor with Tetra Pixel Architecture for Tap Mismatch Calibration and Motion Artifact Suppression

A 640×480 indirect time-of-flight (iToF) image sensor with a 7.2-μm tetra pixel architecture is presented. The proposed tetra pixel architecture consisting of four adjacent pixels shuffles its dual taps to compensate for mismatches and provides in- and quad-phase information at the same time, suppressing motion artifact. In addition, a symmetric trident pinned-photodiode (PPD) structure in each pixel is devised to optimize the alignment with microlens, enhancing the demodulation contrast and sensitivity. The prototype iToF sensor with a VGA resolution was fabricated in a 0.11-μm BSI process and fully characterized. Compared with conventional dual-tap iToF sensors, the measured nonlinearity is improved by about 60%, and the motion artifact is greatly reduced.