1.636 GHz PLL with integrated VCO — what the frequency rating means for the LO chain
The Texas Instruments LMX2531LQ1570E/NOPB is a PLL-based frequency synthesizer (RF) that integrates the VCO and loop filter components into a single 36-WQFN package.
Supply and temperature — sizing the rail and the environment
The supply range is 2.8V to 3.2V, a tighter window than a generic 3.3V rail — the designer should plan a dedicated low-noise LDO or regulator to keep the synthesizer's phase noise clean, especially when the 1.636 GHz output is used as a reference for a mixer or upconverter.
Package and layout — the exposed pad is part of the RF ground
The 2:2 input-to-output ratio means two clock inputs and two CMOS outputs are available, useful for fan-out or redundant reference distribution on the board.
The NOPB suffix confirms lead-free / RoHS3 compliance, matching the majority of modern assembly lines.