Low power CMOS image sensors employing adaptive bulk biasing control (AB²C) approach

A low power CMOS image sensor employing Adaptive Bulk Biasing Control (AB²C) approach is presented. The AB²C is a novel method that utilizes self adaptive biasing of the sensor array and digital periphery and allows sensor power reduction and image performance improvement. The presented AB²C technique can be easily implemented in a standard twin well or triple well CMOS technology. Both rolling shutter and global shutter imagers were examined using the AB²C, showing increased sensor output voltage swing, reduced in-pixel leakage currents, increased shutter efficiency and significant improvement in power dissipation of the scanning circuitry. A detailed description and analysis of the AB²C method is presented. Various image sensors employing AB²C have been implemented in a standard 0.18μm CMOS technology available through MOSIS and are operated via a 1.8V supply. Imagers operation is discussed and simulation results are reported.