High speed data processing for the CMS calorimeter trigger

The CMS level-1 trigger system carefully sifts the 40 MHz data to retain only interesting physics signals at 100 KHz level while discarding the well known QCD background. The level-1 calorimeter trigger electronics discussed here is designed to identify signatures for high energy electrons, photons, neutrinos and jets. At the heart of the trigger system is a custom “backplane” which provides point-to-point links for data sharing between the various trigger cards at 160 MHz. In order to test the feasibility of operation at high frequency we built a complete prototype backplane with 1419 differential point-to-point links. The clock signals on the backplane show rise and fall times below 1 ns with reasonable signal levels even when measured at the farthest card slot