A Content Adapted FPGA Memory Architecture with Pattern Recognition Capability for L1 Track Triggering in the LHC Environment

Modern high-energy physics experiments such as the Compact Muon Solenoid experiment at CERN produce an extraordinary amount of data every 25ns. To handle a data rate of more than 50Tbit/s a multi-level trigger system is required, which reduces the data rate. Due to the increased luminosity after the Phase-II-Upgrade of the LHC, the CMS tracking system has to be redesigned. The current trigger system is unable to handle the resulting amount of data after this upgrade. Because of the latency of a few microseconds the Level 1 Track Trigger has to be implemented in hardware. State-of-the-art pattern recognition filter the incoming data by template matching on ASICs with a content addressable memory architecture. An implementation on an FPGA, which replaces the content addressable memory of the ASIC, has not been possible so far. This paper presents a new approach to a content addressable memory architecture, which allows an implementation of an FPGA based design. By combining filtering and track finding on an FPGA design, there are many possibilities of adjusting the two algorithms to each other. There is more flexibility enabled by the FPGA architecture in contrast to the ASIC. The presented design minimizes the stored data by logic to optimally utilize the available resources of an FPGA. Furthermore, the developed design meets the strong timing constraints and possesses the required properties of the content addressable memory.