A 3.6pW/frame·pixel 1.35V PWM CMOS Imager with Dynamic Pixel Readout and no Static Bias Current

Low-power operation of CMOS imagers using a low voltage (around IV or less) compatible with deep submicron logic circuits enables new imager applications, such as disposable medical cameras and autonomous wireless security cameras on a chip. Pulse width modulation (PWM) is promising for this purpose. A PWM pixel can convert light intensity to a digital pulse width by using an in-pixel comparator with a low power-supply voltage without any degradation of signal-to-noise ratio (SNR). In this paper, we propose and demonstrate a low-power dynamic pixel readout in-pixel comparators(DPR) scheme with CGA PWM pixels based on dynamic operation of in-pixel comparators. DPR requires no static bias current even in the pixel readout. The power dissipation of the pixel array is dramatically reduced by 1 to 2 orders of magnitude compared with using normal static pixel readout (SPR).