The LMX2541 is an ultra low-noise frequency synthesizer which integrates a high
performance delta-sigma fractional N PLL, a VCO with fully integrated tank circuit, and an optional
frequency divider. The PLL offers an unprecedented normalized noise floor of -225 dBc/Hz and can be
operated with up to 104 MHz of phase-detector rate (comparison frequency) in both integer and
fractional modes. The PLL can also be configured to work with an external VCO.
The LMX2541 integrates several low-noise, high precision LDOs and output driver matching
network to provide higher supply noise immunity and more consistent performance, while reducing the
number of external components. When combined with a high quality reference oscillator, the LMX2541
generates a very stable, ultra low-noise signal.
The LMX2541 is offered in a family of 6 devices with varying VCO frequency range from
1990 MHz up to 4 GHz. Using a flexible divider, the LMX2541 can generate frequencies as low as 31.6
The LMX2541 is a monolithic integrated circuit, fabricated in a proprietary BiCMOS
process. Device programming is facilitated using a three-wire MICROWIRE interface that can operate
down to 1.6 volts. Supply voltage ranges from 3.15 V to 3.45 V. The LMX2541 is available in a
36-pin 6-mm × 6-mm × 0.8-mm WQFN Package.