National LMX2470 handbook
Update: 28 September, 2023
The LMX2470 is a low power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. It is fabricated using National Semiconductor’s advanced BiCMOS process. The delta-sigma architecture allows for fractional spur compensation by utilizing the noise shaping capability of the delta-sigma modulator and the low pass filtering of the PLL loop filter. This pushes fractional spurs at lower frequencies to higher frequencies outside the loop bandwidth. The digital feedback techniques used in the LMX2470 are resistant to changes in temperature and variations in wafer processing, unlike analog compensation. The ability to push close in spur and phase noise energy to higher frequencies is directly related to the modulator order, with higher orders allowing for more energy spread to higher frequencies. The LMX2470 has a programmable modulator with a maximum order of four, allowing the designer to select the optimal modulator order for the system's phase noise, spur, and lock time requirements. Programming is simple and fast using a three line MICROWIRE interface. The LMX2470 operates at a nominal supply voltage of 2.5V and has a typical current consumption of 4.1mA. It is available in a 24 lead 3.5 X 4.5 X 0.6 mm package.
Brand: National
File format: PDF
Size: 434 KB
MD5 Checksum: 00FA195003CEDB48C1888D4476757797
Publication date: 06 July, 2012
Downloads: -
PDF Link: National LMX2470 handbook PDF