LMX248x Delta-Sigma Fractional N (Frac-N) PLL Family Home->Clock & Timing Solutions

LMX248x Delta-Sigma Fractional-N PLL Family

LMX248x Family PLL

National's LMX248x Family incorporates the industry's only selectable fourth-order delta-sigma modulator, which enables designers to reach optimal system performance with little effort. These high-performance frequency synthesizers are well-suited for wireless basestations and broad-market radio applications such as wireless local area networks (WLANs), WiMAX, orthogonal frequency division multiplexing (OFDM) loops, test and measurement equipment, satellite up and down links, and automotive applications.

The LMX2485E (extended frequency), LMX2485, LMX2486 and LMX2487 products cover a frequency range of 50 MHz to 6.0 GHz with advanced features that boost performance and ease of use such as:

  • Programmable modulator order up to 4th Order
  • Fractional denominator can be from 1 to 4194303, and every value in-between
  • -55dBc in-band fractional spurs
  • Up to a 22-bit selectable fractional modulus which provides up to 1 Hz frequency resolution
  • Fastlock and cycle slip reduction with timeout counter support
  • Wide frequency range of 50 MHz to 7500 MHz

See additional PLLs on main PLL Homepage

 

Device Main PLL Auxiliary PLL
50 - 3000 MHz 75 - 800 MHz
500 - 3000 MHz 75 - 800 MHz
1000 - 4500 MHz 250 - 3000 MHz
3000 - 6000 MHz 250 - 3000 MHz
863 - 7500 MHz 250 - 3000 MHz

 

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Industry's Highest Performance Frequency Synthesizer System with Integrated VCO

LMX2531LQ1500E PLL +VCO matched for the following A/D converters:

 

PLL Application Notes
  • AN-1879: Fractional N Frequency Synthesis
  • AN-1865: Frequency Synthesis and Planning for PLL Architectures
  • AN-1821: CPRI Repeater System
  • AN-1558: Clocking High-Speed A/D Converters
  • AN-1275: Optimizing LMX243x Input Sensitivity Using Simple Matching Techniques
  • AN-1052: Noise Floor Measurement of PLL Frequency Synthesizers
  • AN-1006: Phase-Locked Loop Based Clock Generators
  • AN-1001: An Analysis and Performance Evaluation of a Passive Filter Design Technique for Charge Pump PLL’s
  • AN-1000: A Fast Locking Scheme for PLL Frequency Synthesizers
  • AN-884: Integrated LNA and Mixer Basics
  • AB-125: Delta Sigma PLLs Raise The Standard For Performance
  • PLL Performance, Simulation and Design Handbook (4th Ed) by Dean Banerjee

 

Other PLL Resources

EasyPLL for LMX PLL/VCO Products

CodeLoader 4.1 for LMK and LMX Devices
National's CodeLoader 4 software is used to program LMK and LMX products through either the USB or LPT port of a computer. Aside from this function, it is also provides information on how to program the part by showing the bits that are actually sent.

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