Development of Binary Readout CMOS Monolithic Sensors for MIP Tracking

Recently, CMOS Monolithic Active Pixels Sensors (MAPS) have become strong candidates for pixel detectors used in high energy physics experiments. A very good spatial resolution lower than 5 mum can be obtained with these detectors. A recent fast MAPS chip, designed in AMS CMOS 0.35 mum Opto process and called MIMOSA16 (HiMAPS2), was submitted to foundry in June 2006. The chip is a 128times32 pixels array where 8 columns have analog test outputs and 24 columns have their outputs connected to offset compensated discriminator stages. The pixel array is addressed row-wise. The array is divided in four blocks of pixels with different charge-to-voltage conversion factors and is controlled by a serially programmable sequencer. The sequencer operates as a pattern generator which delivers control signals both to the pixels and to the column-level discriminators. Discriminators have a common adjustable threshold. This chip is the basis of the final sensor of the EUDET-JRA1 beam telescope which will be installed at DESY in 2009. In this paper, laboratory tests results using a 55Fe source together with beam tests results obtained at CERN using Minimum Ionizing Particles (MIPs) are presented.