LMX2541 Datasheet, PDF (1/70 Pages) National Semiconductor (TI) – Ultra-Low Noise PLLatinum Frequency Synthesizer with Integrated VCO

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LMX2541
SNOSB31J – JULY 2009 – REVISED DECEMBER 2014
LMX2541 Ultra-Low Noise PLLatinum Frequency Synthesizer With Integrated VCO
1 Features
•1 Multiple Frequency Options Available
(See Device Comparison Table)
• Frequencies From 31.6 MHz to 4000 MHz
• Very Low RMS Noise and Spurs
• –225 dBc/Hz Normalized PLL Phase Noise
• Integrated RMS Noise (100 Hz to 20 MHz)
– 2 mRad (100 Hz to 20 MHz) at 2.1 GHz
– 3.5 mRad (100 Hz to 20 MHz) at 3.5 GHz
• Ultra Low-Noise Integrated VCO
• External VCO Option (Internal VCO Bypassed)
• VCO Frequency Divider 1 to 63 (All Values)
• Programmable Output Power
• Up to 104-MHz Phase Detector Frequency
• Integrated Low-Noise LDOs
• Programmable Charge Pump Output
• Partially Integrated Loop Filter
• Digital Frequency Shift Keying (FSK) Modulation
Pin
• Integrated Reference Crystal Oscillator Circuit
• Hardware and Software Power Down
• FastLock Mode and VCO-Based Cycle Slip
Reduction
• Analog and Digital Lock Detect
• 1.6-V Logic Compatibility
2 Applications
• Wireless Infrastructure (UMTS, LTE, WiMax)
• Broadband Wireless
• Wireless Meter Reading
• Test and Measurement
• FM Mobile Radio
space
3 Description
The LMX2541 device is an ultra low-noise frequency
synthesizer which integrates a high-performance
delta-sigma fractional N PLL, a VCO with fully
integrated tank circuit, and an optional frequency
divider. The PLL offers an unprecedented normalized
noise floor of –225 dBc/Hz and can be operated with
up to 104 MHz of phase-detector rate (comparison
frequency) in both integer and fractional modes. The
PLL can also be configured to work with an external
VCO.
The LMX2541 integrates several low-noise, high-
precision LDOs and output driver matching network to
provide higher supply noise immunity and more
consistent performance, while reducing the number of
external components. When combined with a high-
quality reference oscillator, the LMX2541 generates a
very stable, ultra low-noise signal.
The LMX2541 is offered in a family of 6 devices with
varying VCO frequency range from 1990 MHz up to 4
GHz. Using a flexible divider, the LMX2541 can
generate frequencies as low as 31.6 MHz.
The LMX2541 is a monolithic integrated circuit,
fabricated in a proprietary BiCMOS process. Device
programming is facilitated using a three-wire
MICROWIRE interface that can operate down to 1.6
volts. Supply voltage ranges from 3.15 V to 3.45 V.
The LMX2541 is available in a 36-pin 6-mm × 6-mm
× 0.8-mm WQFN package.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
VCO FREQUENCY
(MHz)
LMX2541SQ2060E WQFN (36)
1990 - 2240
LMX2541SQ2380E WQFN (36)
2200 - 2530
LMX2541SQ2690E WQFN (36)
2490 - 2865
LMX2541SQ3030E WQFN (36)
2810 - 3230
LMX2541SQ3320E WQFN (36)
3130 - 3600
LMX2541SQ3740E WQFN (36)
3480 - 4000
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
System Block Diagram
Dirty Input
Clock
PLL
Clean
Reference
Clock
PLL
Ultra-Clean
Local Oscillator
LMK04000
LMX2541
(Clock Jitter Cleaner)
(RF Synthesizer)
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.