A low-power low-noise ultrawide-dynamic-range CMOS imager with pixel-parallel A/D conversion

A CMOS image sensor with pixel-parallel analog-to-digital (A/D) conversion fabricated with different array sizes and photodiode types in a three-metal 0.5-/spl mu/m process is presented. Nominal power dissipation is 40 nW per pixel at V/sub DD/=3.3 V. A/D conversion results from sampling a free-running photocurrent-controlled oscillator to give a first-order /spl Sigma/-/spl Delta/ sequence. The sensor displays dynamic range capability of greater than 150000:1 and exhibits fixed pattern noise correctable to within 0.1% of signal.