150 MHz LVPECL Clock
Basically you need to feed the chip with a clock. The clock needs to be dual phase or differential i.e. clock and clock-bar.

Both these signals (clock and clock-bar) should have an average DC level between 0.1 volts and 3.0 volts).

The differential amplitude of 0.18 to 2.4 volts translates to a single ended amplitude of 0.09 volts to 1.2 volts for either clock or clock-bar.

Rise and fall times - need to be no more than 2ns.

Input duty cycle is basically stating that a 50:50 on-off ratio is preferred but if this ranges between 40% and 60% then it should be OK.