First experimental results with the version TOFHIR2X of the front-end ASIC of the MTD/BTL detector in the CMS experiment

<!--HTML-->TOFHIR2 is the front-end ASIC for the barrel timing layer (BTL) of the MIP timing detector for the CMS upgrade for HL-LHC, aiming at 30-60 ps resolution throughout HL-LHC lifetime. The BTL consists of LYSO:Ce crystals coupled to SiPMs which will suffer radiation damage. Relative to the first version of the front-end ASIC (TOFHIR2A), TOFHIR2X implements improved circuitry for mitigation of the SiPM dark count noise (DCR) as well as a new current mode discriminator. We present an overview of the TOFHIR2 requirements and design, simulation results and the first measurements with TOFHIR2X silicon samples associated to LYSO/SiPM prototype sensors.