FPGA Implementation of Fixed-Latency Command Distribution Based on Aurora 64B/66B

In large-scale physics experiments, clock distribution and time synchronization over multigigabit serial links on one single optical fiber may benefit from the fixed-latency command distribution. For better portability, we make a new design of the off-the-shelf high-speed serial communication protocol Aurora 64B/66B, in which timing commands can be distributed with a fixed latency and clock can be distributed with a predictable phase. This design based on Aurora 64B/66B enables fixed-latency command distribution and fixed-phase clock distribution, with a jitter of few tens of picoseconds. It is available to all field-programmable gate arrays (FPGAs) which are supported in Aurora 64B/66B. The design concept used in our design to eliminate the latency variations in the 64B/66B synchronous gearbox can also be used in designs using the 64B/67B encoding and 10-Gb ethernet application.