Front-end Electronics for GEM detectors

The work presented in this thesis is focused on the design of a 32 channel CMOS front-end ASIC intended for the read-out of GEM detectors to be used in a new proton-therapy facility for beam monitoring. Each single analog channel, based on the classic architecture CSA + shaper, is able to sample the energy of the incoming event by means of a peak detector (PD) which works as an analog memory during the read-out phase. In order to have energy information directly in digital form, the ASIC is equipped with an integrated 8-bit subranging ADC, so the outputs of the PDs are multiplexed towards the A/D conversion path. The outputs of 32 voltage discriminators, which compare the shaper outputs with a programmable threshold, produce an accurate and fast trigger signal which identifies with good time resolution the occurrence of a valid event. The read-out of the channels, the A/D conversion and the configuration of the ASIC are managed by a digital part which also carries out data serialization on a 100 Mbit/s LVDS serial link. Measured results are presented, showing the full functionality of the ASIC and the performance of the analog channel in good agreement with the given specification.