LMX2470 2.6 GHz Delta-Sigma Fractional-N PLL with 800 MHz Integer-N PLL | TI.com

LMX2470 (ACTIVE) 2.6 GHz Delta-Sigma Fractional-N PLL with 800 MHz Integer-N PLL



The LMX2470 is a low power, high performance delta-sigma fractional-N PLL with an auxiliary integer-N PLL. The device is fabricated using TI’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.


  • 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: ICC = 4.1 mA (Typical)

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Design/Analyze/Build It
RF-Side PLL Design Options
Min Output Freq MHz >= 500 help
Max Output Freq MHz <= 2600 help
Channel Spacing KHz > 0 help
AUX-Side PLL Design Options
Min Output Freq MHz >= 75 help
Max Output Freq MHz <= 800 help
Channel Spacing KHz > 0 help
Global Design Options
Crystal Frequency MHz > 0 help
Max Supply V > 0 help

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Part number Order Output frequency (Min) (MHz) Output frequency (Max) (MHz) Normalized PLL phase noise (dBc/Hz) 1/f noise (10-kHz offset at 1-GHz carrier) (dBc/Hz) Current consumption (mA) VCC (V) Integrated VCO
LMX2470 Order now 500     2600     -210     -104     3.9     2.25 to 2.75     No