A 256 Ã\x97 256-Pixel Optical Sensor Architecture with 32 Algorithmic A/D Converters

A 256 × 256-pixel intelligent optical sensor with 32 A/D converters on board is presented. The circuit offers a favourable trade-off between classical architecures based on a single video converter and other architectures involving a very large number of converters. A novel algorithmic A/D converter architecture was designed to achieve the required accuracy at video rate. Fabricated in a 1.2 ¿m standard CMOS process with an added metal 3 light-shielding layer, the circuit is functional and requires a total area of 50 mm².