Design, realization and test of a digital chip for ALICE ITS experiment

CARLOS v3 (Compression And Run Length encOding subSystem) is the name of the third version of a digital radiation hardened chip that plays a significant role in the data acquisition chain of the ALICE experiment (A Large Ion Collider Experiment) for what concerns the Inner Tracking System (ITS). In particular CARLOS has the purpose of performing an on-line compression on data coming from two half detectors SDDs (Silicon Drift Detectors). In fact data volume of SDD events and trigger rate require the use of an on-line compression device with high performances for what concerns compression coefficient and total throughput. The chip has been tested using a specific PCB (Printed Circuit Board) containing the connectors for probing the ASIC with a pattern generator and a logic state analyzer. The chips have been inserted on the PCB using a ZIF socket, that allowed us to test the 35 packaged samples out of the total amount of bare chips received from the foundry. The test phase has shown that 32 out of 35 chips under test work well. CARLOS v3 has been successfully used in the readout chain implemented at CERN during the August 2003 beam test.