A 80µW 30fps 104 × 104 all-nMOS pixels CMOS imager with 7-bit PWM ADC for robust detection of relative intensity change

The presented vision sensor features low-power pixel-level programmable dynamic background subtraction as low-level image processing aimed at detecting unusual events occurring in the scene. Each pixel compares its current photogenerated signal with two threshold voltages, defining the boundary conditions outside which the signal is to be considered anomalous, if compared to its past history. In case of anomalous behavior, the pixel one-bit output will be asserted. The 17 transistors square pixel has a pitch of 16μm with a fill-factor of 21%. The 104 × 104 pixel sensor, fabricated in a 0.35 μm CMOS, has a power consumption of 80μW at 30 fps, when the sensor array is powered at 3.3V and the digital part at 1.5V. This turns into a pixel power consumption per frame of 246pW/pixel · frame.