A 0.5V 4.95μW 11.8fps PWM CMOS imager with 82dB dynamic range and 0.055% fixed-pattern noise

Abstract

Lately, developing a low-voltage, power-efficient image sensor for disposable or implantable biomedical devices has become an important topic [1,2]. Instead of using a conventional CMOS active pixel sensor (APS), converting a photo-generated signal into the time domain using pulse width modulation (PWM) has become a popular way to overcome the limited signal swing under low-voltage operation [2,3,4,5]. Our design offers solutions to the following problems: 1) threshold-variation effects in PWM-based sensors, and 2) the low dynamic range of circuits with low supply voltage. © 2012 IEEE.