Texas Instruments LMX2491 Low-Noise Fractional N PLL

Texas Instruments LMX2491 Low-Noise Fractional-N PLL is a 6.4GHz wideband delta-sigma fractional-N PLL with ramp and chirp generation. This device consists of a phase frequency detector, programmable charge pump, and high-frequency input for the external VCO. The LMX2491 supports a broad and flexible class of ramping capabilities, including FSK, PSK, and configurable piecewise linear FM modulation profiles of up to 8 segments. The device supports fine PLL resolution and a fast ramp with up to a 200MHz phase detector rate. The LMX2491 allows any of its registers to be read back. The Texas Instruments LMX2491 can operate with a single 3.3V supply. Moreover, supporting up to a 5.25V charge pump can eliminate the need for an external amplifier, leading to a more straightforward solution with improved phase noise performance.

Features

  • –227dBc/Hz normalized PLL noise
  • 500MHz to 6.4GHz wideband PLL
  • 3.15V to 5.25V charge pump PLL supply
  • Versatile ramp/chirp generation
  • 200MHz maximum phase detector frequency
  • FSK / PSK modulation pin
  • Digital lock detect
  • Single 3.3V supply capability

Applications

  • FMCW radars
  • Military radars
  • Microwave backhaul
  • Test and measurement
  • Satellite communications
  • Wireless infrastructure
  • Sampling clock for high-speed ADC/DAC

Simplified Schematic

Schematic - Texas Instruments LMX2491 Low-Noise Fractional N PLL
Publicado: 2017-04-26 | Actualizado: 2022-04-26