3.1 GHz fanout — what the speed grade buys
The LMK00301ARHST: The 3.1 GHz maximum frequency sets the upper bound for clock distribution in high-speed serial links — PCIe Gen 4 (16 GT/s), 100G Ethernet (25.78125 Gb/s per lane), and JESD204B interfaces all run reference clocks well within this ceiling. The device functions as a fanout buffer, multiplexer, and level translator rolled into one package. With a 3:11 input-to-output ratio, one of three selectable input banks (each accepting CML, HCSL, HSTL, LVDS, LVPECL, SSTL, or crystal) can be fanned out to eleven outputs in HCSL, LVCMOS, LVDS, or LVPECL formats. This eliminates external translation logic between clock sources and downstream PLLs or SerDes devices.
Supply rail and temperature envelope
The supply range is 3.15 V to 3.45 V — a tight 300 mV window centred on 3.3 V. This is typical for high-performance clock buffers where PSRR matters; the rail needs a clean 3.3 V supply with less than 30 mV ripple to stay within spec. The 0.5 mm pitch QFN demands a 4-layer PCB for reliable fan-out of the 48 pins.
Differential signal path — all the way through
Both the input and output stages are differential-capable (Yes/Yes per the spec), meaning the device preserves signal integrity across the entire fanout tree without single-ended conversion loss. This is critical for sub-1 ps additive jitter budgets in 25+ Gb/s serial links where a single-ended stub would degrade the eye diagram. The single-circuit configuration (one buffer per package) means a clock-tree design using multiple LMK00301ARHST devices will have independent fanout blocks — useful for isolating clock domains or distributing redundant references without crosstalk through a shared die.