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

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Select

Parametric Tables

Phase-Locked Loops

• Fractional PLL
• Fractional PLL +VCO
• Integer PLL

Clock Jitter Cleaners

• With External Crystal
• With External VCXO
• With Integrated VCO

Related National Product Sites

• PLL Homepage
• Clock & Timing
• Broadcast Video Timing
• LVDS/CML
• Data Conversion

Design

Evaluation Boards

• LMX PLLatinum™ PLL/VCO Evaluation Boards

Clock and Timing Software

• CodeLoader
• EasyPLL WEBENCH Online PLL Simulator Tool

Application Notes

• Phase-Locked Loops (PLL)

Explore

PLL Handbook

• PLL Performance, Simulation and Design Handbook (4^th Edition) by Dean Banerjee

PLL Online Seminar

• Advantages and Pitfalls of Using Fractional N PLLs