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PLL and PLL + VCO Solutions

National's PLL Family Portfolio includes the industry's lowest noise monolithic PLL integrated circuits and frequency synthesizers with the industry's best spur performance for better signal sensitivity in voice and data systems.

The LMX2541 Family is the world's lowest noise integrated frequency synthesizer. Featuring the world’s lowest noise phase-locked loop (PLL) with bypass-able integrated VCO, the LMX2541 provides less than 2 milli-radians (mrad) root-mean-square (RMS) noise at 2.1 GHz and 3.5 mrad RMS noise at 3.5 GHz, outperforming the nearest competitor by 10 dB in both in-band PLL noise and spurious performance. When paired with the LMK04000 clock jitter cleaner, the LMX2541 significantly improves system error vector magnitude (EVM), resulting in enhanced receiver sensitivity and transmitter spectral purity.

The LMX2531 Family is an integrated PLL+VCO family that delivers both high performance and a high degree of integration. National's LMX2531 Family is well suited for cellular infrastructure as well as broad-market applications including automotive, satellite, and test and measurement equipment.

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.

 

  LMX248x Family LMX243x Family LMX2531 Family LMX2541 Family New!
Fractional or Integer PLL Both Integer Both Both
Single or Dual PLL Dual Dual Single Single
Normalized Phase Noise (dBc/Hz) -210 -219 -212 -225
Integrated VCO No No Yes Yes (can be bypassed)
Min Frequency (MHz) 50 100 553 31.6
Max Frequency (MHz) 7500 5000 2790 4000
Supply Voltage (V) 2.5 - 3.6 2.25 - 2.75 2.8 - 3.2 3.15 - 3.45

 

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Phase-Locked Loops

Clock Jitter Cleaners

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Recommended Support Products

  • LM6211 Op amp for active filters
  • LP5900 Ultra-low noise LDO for PLL supplies
  

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PLL Handbook

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WHAT'S NEW
PLL Products

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.

Evaluation Boards

Online Seminars

PLL Handbook

 



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