A digital Front-End and Readout MIcrosystem for calorimetry at LHC

% RD-16 A Digital Front-End and Readout Microsystem for Calorimetry at LHC \\ \\Front-end signal processing for calorimetric detectors is essential in order to achieve adequate selectivity in the trigger function of an LHC experiment, with data identification and compaction before readout being required in the harsh, high rate environment of a high luminosity hadron machine. Other crucial considerations are the extremely wide dynamic range and bandwidth requirements, as well as the volume of data to be transferred to following stages of the trigger and readout system. These requirements are best met by an early digitalization of the detector information, followed by integrated digital signal processing and buffering functions covering the trigger latencies.\\ \\The FERMI (Front-End Readout MIcrosystem) is a digital implementation of the front-end and readout electronic chain for calorimeters. It is based on dynamic range compression, high speed A to D converters, a fully programmable pipeline/digital filter chain, local storage and trigger functions. FERMI also acts as the interface to the Trigger and DAQ systems.\\ \\In the current demonstrator design six parallel acquisition channels consisting of a non-linear or switched multi-gain amplifier for 16/17 bit to 12 bit dynamic range compression. The signals are then sampled and digitised by 40~MHz, 12-bit ADCs. After linearisation and absolute calibration in look-up tables or add-multiply processes, the data are stored in dual port memories until the decision is taken by the first level trigger.\\ \\For the level-1 trigger, the data from all enabled channels are discriminated, added and summed over time to emulate pulse integration. The readout logic provides full time frames, up to 16~samples long, and/or digitally filtered data to the second and third level stages.\\ \\An integration of FERMI into a multi-chip Silicon-on-Silicon module (MCM-D) has been done using the flip-chip ASIC mounting technology. This solution allows a very high level of integration of complex functions with an excellent flexibility in mixing technologies for the different functional blocks.\\ \\Since FERMI is designed to be mounted in the immediate vicinity of the calorimeter, it incorporates a high degree of fault-tolerant circuitry and programmability, as well as the possible use of a rad-hard or rad-tolerant technologies.\\ \\Tests have been done together with detector prototypes for the ATLAS LAr and Tiles as well as with CMS crystal ECAL, and the results show that FERMI provides more than adequate performances for these detectors.\\ \\