The Texas Instruments LMX2531LQ1650E/NOPB is a PLL-based frequency synthesizer with an integrated VCO, designed for RF local-oscillator generation in wireless infrastructure, test equipment, and microwave backhaul. It accepts a clock input and delivers a CMOS output up to 1.7 GHz, covering bands such as cellular base-station LO synthesis and ISM-band signal chains. The single-circuit device uses a 2:2 input-to-output ratio, and the integrated divider/multiplier allows flexible frequency planning without external VCO modules.
The 1.7 GHz upper limit sets the synthesizer's usable range for LO generation. The CMOS output drives standard digital PLL inputs directly, so no external level shifter is needed between the synthesizer and the downstream mixer or modulator.
The 2.8V to 3.2V supply aligns with common 3.0V and 3.3V RF rails — check your regulator's tolerance, especially at cold-crank where the rail may dip toward 2.8V. The part remains operational within that window.
Package and thermal handling for RF layout
The 6x6 mm body with exposed pad demands a solid ground-plane via stitch under the pad for both thermal dissipation and RF grounding. The pad is the main heat path — without adequate vias, junction temperature climbs quickly above 85°C ambient.