7.1 Overview

The LMX2572LP is a low-power, high-performance, wideband frequency synthesizer with integrated VCO and output divider. The VCO operates from 3.2 to 6.4 GHz, and this can be combined with the output divider to produce any frequency in the range of 12.5 MHz to 2 GHz. Within the input path, there are two dividers and a multiplier for flexible frequency planning. The multiplier can also move the frequencies away from the integer boundary to allow spur reduction.

The PLL is a fractional-N PLL with a programmable delta-sigma modulator up to 4^th order. The fractional denominator is a programmable 32-bit long that can supply fine frequency steps easily below the 1-Hz resolution. The denominator can also be used to do exact fractions like 1/3, 7/1000, and many others.

For applications where deterministic or adjustable phase is desired, the SYNC pin can be used to get the phase relationship between the OSCin and RFout pins deterministic. Once this is done, the phase can be adjusted in very fine steps of the VCO period divided by the fractional denominator.

The ultra-fast VCO calibration is ideal for applications where the frequency must be swept or abruptly changed. The frequency can be manually programmed, or the device can be set up to do ramps and chirps.

The FSK generator can support FSK generation in discrete 2-, 4-, or 8-level FSK. It can also support an arbitrary level FSK.

The LMX2572LP device requires only a single 3.3-V power supply and uses very low current. The internal power supplies are provided by integrated LDOs, eliminating the need for high performance external LDOs.

Digital logic interface is compatible with 1.8-V input. The user can program the device through the serial interface. The device can be powered down through register programming or by toggling the Chip Enable (CE) pin.