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. It accepts a clock input and delivers a CMOS output up to 1.636 GHz, making it a direct fit for local-oscillator generation in wireless infrastructure, microwave backhaul, and test equipment where a clean, programmable RF carrier is needed without an external VCO module.
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. The operating temperature range of -40°C to 85°C covers outdoor telecom cabinets, base-station shelters, and industrial RF test racks; the industrial grade means no derating concerns for equipment that sees seasonal thermal cycling.
Package and layout — the exposed pad is part of the RF ground
Housed in a 36-WFQFN with an exposed pad (supplier device package 36-WQFN 6x6 mm), the thermal pad must be soldered to a ground plane with a via array for both heat dissipation and low-inductance RF return. 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.
Lifecycle and sourcing — active production, no LTB risk
The LMX2531LQ1570E/NOPB carries an active lifecycle status and is ROHS3 compliant. The NOPB suffix confirms lead-free / RoHS3 compliance, matching the majority of modern assembly lines.