Architecture and Performance of the Upgraded CMS Calorimeter Trigger

The CMS Level-1 calorimeter trigger was completely upgraded before the start of the 2016 data-taking. The upgraded system ran successfully during Run 2 and will continue running throughout Run 3. Its novel time-multiplexed architecture is made possible by large FPGAs connected by fastoptical links, operating in MicroTCA chassis. We describe the architecture of the system and the hardware used to implement it. In particular, examples of advanced trigger algorithms enabled by the time-multiplexed design are discussed. Precise FPGA floorplanning allows placing all calorimeter trigger algorithms in a single board. The performance of the system is presented based on the 2016–2018 data taking of proton collisions at the LHC.