A pixel readout chip for tracking at ALICE and particle identification at LHCb

The ALICE1 chip is a mixed-mode integrated circuit to read out silicon pixel detectors used for particle tracking in the ALICE Silicon Pixel Detector or particle identification in the LHCb Ring Imaging Cherenkov detector. The chip will be fabricated in a commercial 0.25Pm technology and transistors are designed with a radiation-tolerant geometry. It consists of 256 u 32 pixel cells, each of 50Pm u 400Pm, and can be operated in one of two modes. In tracking mode, all cells are read out. In particle identification mode, 8 cells are grouped together, reducing the effective granularity to 32 u 32 cells of 400Pm u 400Pm. The cell architecture is described in detail, together with the two operational modes and issues of system integration.