The IDT5T940 generates a high precision FEC (Forward Error Correction) or non-FEC source clock for SONET/SDH systems as well as a source clock for Gigabit Ethernet systems. This device also has clock regeneration capability: it creates a "clean" version of the clock input by using the internal oscillator to square the input clock's rising and falling edges and remove jitter. In the event that the main clock input fails, the device automatically locks to a backup reference clock using a hitless switchover mechanism.