LMX2470_14 Datasheet, PDF (1/38 Pages) Texas Instruments – 2.6 GHz Delta-Sigma Fractional-N PLL with 800 MHz Integer-N PLL

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
FEATURES
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•2 Low in-band phase noise and low fractional
spurs
• 12 bit or 22 bit selectable fractional modulus
• Up to 4th order programmable delta-sigma
modulator
• Enhanced Anti-Cycle Slip Fastlock Circuitry
– Fastlock
– Cycle slip reduction
– Integrated timeout counters
• Digital lock detect output
• Prescalers allow wide range of N values
– RF PLL: 16/17/20/21
– IF PLL: 8/9 or 16/17
• Crystal Reference Frequency up to 110 MHz
• On-chip crystal reference frequency doubler.
• Phase Comparison Frequency up to 30 MHz
• Hardware and software power-down control
• Ultra low consumption: I_CC = 4.1 mA (typical)
APPLICATIONS
• Cellular Phones and Base Stations
– CDMA, WCDMA, GSM/GPRS, TDMA, EDGE,
PDC
• Applications requiring fine frequency
resolution
• Satellite and Cable TV Tuners
• WLAN Standards
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.
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004, Texas Instruments Incorporated