A pixel column level, ultra low power, 9Msample/s multi bit A/D converter for Monolithic Active Pixel Sensors in high energy physics

Monolithic active pixel sensors (MAPS) using standard low cost CMOS technology available from industrial manufacturers have demonstrated excellent tracking performances for minimum ionizing particles and biomedical imaging applications. The need for highly granular, fast, thin sensors with a full digital output drives a R&D effort, aiming to design and optimize an ultra low power high speed A/D converter integrated in column level. Following this main issue, a multibit A/D converter has been proposed for CMOS monolithic active pixel sensors in this paper. This A/D converter responds to the constraints of size, power dissipation and speed of the CMOS sensors for particles detections. The A/D converter developed has a resolution of 4 bits for a speed of conversion of 9 Msample/s with only 270 muW of static consumption in a very particular pitch size of 25 mum times 1275 mum.