Clock distribution and synchronization over 1000BASE-T Ethernet

Abstract

We report on a Synchronous Ethernet based clock distribution and timestamp synchronization implementation over 1000BASE-T (Gigabit over twisted pair) Ethernet. A central 125 MHz global clock is distributed to all detector modules using only commercial off-the-shelf components. The timestamps generated on different modules has a maximum fixed offset of 24–60 ns (depending on the switch tested), and a jitter of less than 500 ps (with no clock cleaner IC being used).