Development of the XFEL timing system

The European XFEL project requires a high-speed and high-quality clock and trigger distribution system. The main clock frequency is 1.3 GHz and needs to be distributed over several kilometers of distance. At each destination several clock frequencies needs to be derived and triggers needs to be decoded. All clocks and triggers must be phase stable throughout the entire system. However, every component, such as fiber cables and electronic ICs, are drifting with temperature changes. These changes are monitored and compensated. Jitter must be kept below 5 ps (RMS). Three prototypes have been created so far. An evaluation board to test the key concept of the system and a fully functional Advanced Mezzanine Card (AMC), of which a second revision have been designed and manufactured. This paper will describe key concept of the timing system while focus a little bit more on the latest revision of the boards and firmware development.