The CMS Tracker under development for the High Luminosity LHC includes an outer
tracker based on “PT-modules” which will provide track stubs based on coincident clusters in two
closely spaced sensor layers, aiming to reject low transverse momentum track hits before data
transmission to the Level-1 trigger. The tracker data will be used to reconstruct track segments in
dedicated processors before onward transmission to other trigger processors which will combine
tracker information with data originating from the calorimeter and muon detectors, to make the
final L1 trigger decision. The architecture for processing the tracker data is still an open question.
One attractive option is to explore a Time Multiplexed design similar to one which is currently
being implemented in the CMS calorimeter trigger as part of the Phase I trigger upgrade. The Time
Multiplexed Trigger concept is explained, the potential benefits of applying it for processing future
tracker data are described and a possible design based on currently existing hardware is presented.