LMX2470
www.ti.com
SNAS195A –MAY 2004–REVISED MAY 2004
LMX2470 2.6 GHz Delta-Sigma Fractional-N PLL with 800 MHz Integer-N PLL
Check for Samples: LMX2470
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FEATURES
• On-chip crystal reference frequency doubler.
• Phase Comparison Frequency up to 30 MHz
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• Low in-band phase noise and low fractional
spurs
• Hardware and software power-down control
• 12 bit or 22 bit selectable fractional modulus
• Ultra low consumption: I
CC
= 4.1 mA (typical)
• Up to 4th order programmable delta-sigma
APPLICATIONS
modulator
• Enhanced Anti-Cycle Slip Fastlock Circuitry • Cellular Phones and Base Stations
– Fastlock – CDMA, WCDMA, GSM/GPRS, TDMA, EDGE,
PDC
– Cycle slip reduction
• Applications requiring fine frequency
– Integrated timeout counters
resolution
• Digital lock detect output
• Satellite and Cable TV Tuners
• Prescalers allow wide range of N values
• WLAN Standards
– RF PLL: 16/17/20/21
– IF PLL: 8/9 or 16/17
• Crystal Reference Frequency up to 110 MHz
DESCRIPTION
The LMX2470 is a low power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL.
The device is fabricated using National Semiconductor’s advanced BiCMOS process.
With delta-sigma architecture, fractional spur compensation is achieved with noise shaping capability of the delta-
sigma modulator and the inherent low pass filtering of the PLL loop filter. Fractional spurs at lower frequencies
are pushed to higher frequencies outside the loop bandwidth. Unlike analog compensation, the digital feedback
techniques used in the LMX2470 are highly resistant to changes in temperature and variations in wafer
processing. With delta-sigma architecture, the ability to push close in spur and phase noise energy to higher
frequencies is a direct function of the modulator order. The higher the order, the more this energy can be spread
to higher frequencies. The LMX2470 has a programmable modulator up to order four, which allows the designer
to select the optimum modulator order to fit the phase noise, spur, and lock time requirements of the system.
Programming is fast and simple. Serial data is transferred into the LMX2470 via a three line MICROWIRE
interface (Data, Clock, Load Enable). Nominal supply voltage is 2.5 V. The LMX2470 features a typical current
consumption of 4.1 mA at 2.5 V. The LMX2470 is available in a 24 lead 3.5 X 4.5 X 0.6 mm package.
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Copyright © 2004, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
