Product details

Integrated VCO Yes Output frequency (Min) (MHz) 50 Output frequency (Max) (MHz) 3760 Normalized PLL phase noise (dBc/Hz) -229 Current consumption (mA) 178 1/f noise (10-kHz offset at 1-GHz carrier) (dBc/Hz) -125
Integrated VCO Yes Output frequency (Min) (MHz) 50 Output frequency (Max) (MHz) 3760 Normalized PLL phase noise (dBc/Hz) -229 Current consumption (mA) 178 1/f noise (10-kHz offset at 1-GHz carrier) (dBc/Hz) -125
WQFN (RTV) 32 25 mm² 5 x 5
  • Output Frequency from 50 to 3760 MHz
  • Input Clock Frequency up to 900 MHz
  • Phase Detector Frequency up to 200 MHz
  • Supports Fractional and Integer Modes
  • –229 dBc/Hz Normalized PLL Phase Noise
  • –120.8 dBc/Hz Normalized PLL 1/f Noise
  • –137 dBc/Hz VCO Phase Noise @ 1 MHz
    offset for a 2.5 GHz Carrier
  • 100 fs RMS Jitter in Integer Mode
  • Programmable Fractional Modulator Order
  • Programmable Fractional Denominator
  • Programmable Output Power up to +12 dBm
  • Programmable 32 Level Charge Pump Current
  • Programmable Option to Use an External VCO
  • Digital Lock Detect
  • 3-Wire Serial Interface and Readback
  • Single Supply Voltage from 3.15 V to 3.45 V
  • Supports Logic Levels down to 1.6 V
  • Output Frequency from 50 to 3760 MHz
  • Input Clock Frequency up to 900 MHz
  • Phase Detector Frequency up to 200 MHz
  • Supports Fractional and Integer Modes
  • –229 dBc/Hz Normalized PLL Phase Noise
  • –120.8 dBc/Hz Normalized PLL 1/f Noise
  • –137 dBc/Hz VCO Phase Noise @ 1 MHz
    offset for a 2.5 GHz Carrier
  • 100 fs RMS Jitter in Integer Mode
  • Programmable Fractional Modulator Order
  • Programmable Fractional Denominator
  • Programmable Output Power up to +12 dBm
  • Programmable 32 Level Charge Pump Current
  • Programmable Option to Use an External VCO
  • Digital Lock Detect
  • 3-Wire Serial Interface and Readback
  • Single Supply Voltage from 3.15 V to 3.45 V
  • Supports Logic Levels down to 1.6 V

The LMX2581 is a low noise wideband frequency synthesizer that integrates a delta-sigma fractional N PLL, multiple core VCO, programmable output divider, and two differential output buffers. The VCO frequency range is from 1880 to 3760 MHz and can be sent directly to the output buffers or divided down by even values from 2 to 38. Each buffer is capable of output power from –3 to +12 dBm at 2700 MHz. Integrated low noise LDOs are used for superior noise immunity and consistent performance.

This synthesizer is a highly programmable device and it enables the user to optimize its performance. In fractional mode, the denominator and the modulator order are programmable and can be configured with dithering as well. The user also has the ability to directly specify a VCO core or entirely bypass the internal VCO. Finally, many convenient features are included such as power down, Fastlock, auto mute, and lock detection. All registers can be programmed through a simple 3 wire interface and a read back feature is also available.

The LMX2581 operates on a single 3.3 V supply and comes in a 32 pin 5.0 mm × 5.0 mm WQFN package.

The LMX2581 is a low noise wideband frequency synthesizer that integrates a delta-sigma fractional N PLL, multiple core VCO, programmable output divider, and two differential output buffers. The VCO frequency range is from 1880 to 3760 MHz and can be sent directly to the output buffers or divided down by even values from 2 to 38. Each buffer is capable of output power from –3 to +12 dBm at 2700 MHz. Integrated low noise LDOs are used for superior noise immunity and consistent performance.

This synthesizer is a highly programmable device and it enables the user to optimize its performance. In fractional mode, the denominator and the modulator order are programmable and can be configured with dithering as well. The user also has the ability to directly specify a VCO core or entirely bypass the internal VCO. Finally, many convenient features are included such as power down, Fastlock, auto mute, and lock detection. All registers can be programmed through a simple 3 wire interface and a read back feature is also available.

The LMX2581 operates on a single 3.3 V supply and comes in a 32 pin 5.0 mm × 5.0 mm WQFN package.

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Technical documentation

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Type Title Date
* Data sheet LMX2581 Wideband Frequency Synthesizer with Integrated VCO datasheet (Rev. G) 05 Sep 2014
User guide LMX2581EVM User's Guide (Rev. C) 25 Nov 2013
Technical article High-speed design: Why phase noise matters! 02 Aug 2013

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

LMX2581EVM — LMX2581EVM Evaluation Module

The LMX2581 Wideband frequency synthesizer allows the generation of a broad range of frequencies with excellent phase noise. The LMX2581 Reference Board (LMX2581EVM) is designed to assist in the evaluation of the LMX2581 in a system, as well as serve as a reference design for the customer’s (...)

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Evaluation board

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The TSW16DX370EVM is a reference design board used to evaluate the high performance receiver IF super-heterodyne subsystem solution including the following products from Texas Instruments:

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Application software & framework

CLOCKDESIGNTOOL — Clock Design Tool - Loop Filter & Device Configuration + Simulation

The Clock Design Tool software helps with part selection, loop filter design and simulation of timing device solutions. When you enter desired output frequencies and a reference frequency (optional), the tool provides TI devices to meet the specified requirements, divider values and a recommended (...)
Application software & framework

PLLATINUMSIM-SW — Texas Instruments PLLatinum Simulator Tool

The PLLATINUMSIM-SW simulator tool lets you create detailed designs and simulations of our PLLATINUM™ integrated circuits which include the LMX series of PLLs and synthesizers.
Application software & framework

TICSPRO-SW — Texas Instruments Clocks and Synthesizers (TICS) Pro Software

The TICS Pro software is used to program the evaluation modules (EVMs) for device numbers with these prefixes: CDC, LMK and LMX. These devices include PLLs and voltage-controlled oscillators (PLL+VCO), synthesizers and clocking devices.
IDE, configuration, compiler or debugger

CODELOADER — CodeLoader Software for device register programming

The CodeLoader 4 software is used to program the LMX PLLs and LMK timing devices through either the USB or line print terminal (LPT) port of a computer. This software also provides information on how to program the device by showing the bits that are actually sent.


Which software do I use?

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Simulation model

LMX2581 IBIS Model

SNAM157.ZIP (54 KB) - IBIS Model
Design tool

CLOCK-TREE-ARCHITECT — Clock tree architect programming software

Clock tree architect is a clock tree synthesis tool that streamlines your design process by generating clock tree solutions based on your system requirements. The tool pulls data from an extensive database of clocking products to generate a system-level multi-chip clocking solution.
Reference designs

TIDA-00426 — 12-Gbps Multi-Channel BERT Board Reference Design

This reference design is a 12-Gbps low-cost bit error tester (BERT) capable of generating and checking up to 8 channels of pseudo-random binary sequences (PRBS). This validated design is a convenient way to generate multi-channels high speed serial bit streams of up to 12-Gbps, and checking (...)
Reference designs

TIDA-00360 — 700–2700 MHz Dual-Channel Receiver with 16-Bit ADC and 100 MHz IF Bandwidth Reference Design

The increasing demand on wireless networks to provide faster data links to customers has driven transceiver hardware to increasingly demanding performance with enough bandwidth to support the largest standardized multi-carrier frequency bands (with band aggregation in some cases) and enough (...)
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WQFN (RTV) 32 View options

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