Recent developments in 130-nm CMOS monolithic active pixel detectors

We developed monolithic active pixel detectors, by exploiting the triple well option available in a deep-submicron CMOS process. The novel features are the full analog signal processing and digital functionality implemented at the pixel level. The charge collecting element is realized using the deep N-well (DNW), the full in-pixel signal processing chain includes charge preamplifier, shaper, discriminator and latch. We report on the characterization of the two prototype chips, the first (APSEL0) containing single-channel sensors, with different collecting electrode area, and the latter (APSEL1) with several single pixel structures with improved noise figure implementing also an 8 × 8 matrix of 50 × 50 μm2 pixel area. So far, the pixel matrix has a simple row by row readout, successfully tested with clock frequency up to 30 MHz. The response of the sensors to infra-red laser, β-rays and soft X-rays (from radioactive sources, 90Sr and 55Fe respectively) will be presented. The results achieved so far demonstrate the viability of the technology and suggest new design improvements implemented in the next prototype chips submission (APSEL2).