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National Semiconductor Introduces Industry’s Lowest Phase Noise Single-Chip PLL + VCO

-- National’s High Performance LMX2531 Provides Flexibility, Wide Frequency Range (765MHz to 2790MHz) for Cellular Infrastructure, Broad-Market Applications

Oct 31, 2005

October 31, 2005 - National Semiconductor Corporation (NYSE:NSM) today introduced the LMX2531, the industry’s lowest phase noise monolithic phase-locked loop and voltage-controlled oscillator (PLL + VCO) integrated circuit.  With a frequency range of 765 MHz to 2790 MHz and a noise floor better than -160 dBc/Hz, National’s LMX2531 is well suited for cellular infrastructure as well as broad-market applications such as automotive, satellite, and test and measurement equipment.

Leveraging National’s expertise in radio frequency (RF) design and advanced process technology, National’s team of designers developed the LMX2531, an integrated PLL + VCO that delivers both high performance and a high degree of integration.  This enables design engineers to generate solutions that have a lower bill of materials as well as a smaller circuit footprint.

The LMX2531 incorporates the world’s first delta sigma Fractional-N PLL architecture specifically designed to meet the stringent requirements of the 3G basestation market.  Delta sigma architectures offer significant advantages over more conventional Integer-N approaches because they can deliver superior phase noise and spurious performance as well as increased flexibility to implement various channel spacing schemes.

“The LMX2531 offers our customers a better alternative to other bulky and costly PLL + VCO solutions because it reduces printed circuit board space and total system cost,” said John Johnson, director of National’s Timing Devices Business Unit. “Using our new proprietary delta-sigma architecture, the LMX2531 is ideal for applications where design engineers seek to collectively optimize factors such as reducing phase noise and spurious performance.”

Pricing and Availability
The LMX2531 is available now in a 36-pin LLP package and is priced at $6.65 each in 1K-unit quantities. More information is available at

Note to editors: To view a high-resolution downloadable photo of the LMX2531, http://www.national.com/company/pressroom/gallery/wireless.html

About National Semiconductor
National Semiconductor, the industry's premier analog company, creates high-value analog devices and subsystems.  National's leading-edge products include power management circuits, display drivers, audio and operational amplifiers, communication interface products and data conversion solutions. National's key analog markets include wireless handsets, displays and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, California, National reported sales of $1.91 billion for fiscal 2005, which ended May 29, 2005.  Additional company and product information is available at www.national.com