6.4 GHz PLL synthesizer in a 24-WQFN package
The LMX2491RTWT is a PLL-based frequency synthesizer that covers a 6.4 GHz maximum output frequency — this places it in the C-band and upper S-band for radar local oscillators, 5G test equipment, and microwave backhaul frequency generation. The 2:1 input-to-output ratio means an internal mux selects between two clock references before feeding the phase detector — useful for redundant reference or switching between a clean crystal and a system clock without an external RF switch.
Supply rail and board integration
A dedicated LDO feeding this rail is the standard practice. The differential input and output are both marked No, so the reference input and RF output are single-ended — the layout must keep the 50-ohm trace from the output pin to the next stage as short as possible to minimize parasitic inductance at 6.4 GHz.