LMX2491 Datasheet, PDF (1/31 Pages) Texas Instruments – 6.4-GHz Low Noise RF PLL With Ramp/Chirp Generation

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LMX2491
SNAS711 – OCTOBER 2016
LMX2491 6.4-GHz Low Noise RF PLL With Ramp/Chirp Generation
1 Features
•1 –227-dBc/Hz Normalized PLL Noise
• 500-MHz to 6.4-GHz Wideband PLL
• 3.15-V to 5.25-V Charge Pump PLL Supply
• Versatile Ramp / Chirp Generation
• 200-MHz Maximum Phase Detector Frequency
• FSK / PSK Modulation Pin
• Digital Lock Detect
• Single 3.3-V Supply Capability
2 Applications
• FMCW Radars
• Military Radars
• Microwave Backhaul
• Test and Measurement
• Satellite Communications
• Wireless Infrastructure
• Sampling Clock for High-Speed ADC/DAC
3 Description
The LMX2491 device is a low-noise, 6.4-GHz
wideband delta-sigma fractional N PLL with ramp and
chirp generation. It 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. It supports fine PLL resolution and fast
ramp with up to a 200-MHz phase detector rate. The
LMX2491 allows any of its registers to be read back.
The LMX2491 can operate with a single 3.3-V supply.
Moreover, supporting up to 5.25-V charge pump can
eliminate the need of external amplifier, leading to a
simpler solution with improved phase noise
performance.
PART NUMBER
LMX2491
Device Information
PACKAGE
BODY SIZE (NOM)
WQFN (24)
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
OSCin
51 Ÿ
51 Ÿ
GND/OSCin*
GND (x3)
CE
CLK
DATA
LE
2X
MICROWIRE
Interface
TRIG1
TRIG2
MOD
MUXout
MUX
Modulation
Generator
R Divider
(16 bit)
Phase
Comp
N Divider
(18 bit)
û
Compensation
(24 bit)
Charge
Pump
CPout
C2_LF
Vcp ^C1_LF
Vcc (x5)
R2_LF
Fin
18 Ÿ
36 Ÿ
Fin*
51 Ÿ
68 Ÿ
Copyright © 2016, Texas Instruments Incorporated
18 Ÿ
18 Ÿ _{To Circuit}
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.