Wideband Frequency Synthesizer with Integrated VCO - LMX2581E

LMX2581E (ACTIVE)

Wideband Frequency Synthesizer with Integrated VCO

 

Description

The LMX2581E 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 3800 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 LMX2581E operates on a single 3.3 V supply and comes in a 32 pin 5.0 mm × 5.0 mm WQFN package.

Features

  • Output Frequency from 50 to 3800 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 at 1 MHz offset
    for a 2.5 GHz Carrier
  • 100 fs RMS Jitter in Integer Mode
  • Programmable Fractional ModulatorOrder
  • 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

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Parametrics Compare all products in RF PLLs and Synthesizers

 
Output Frequency (Min) (MHz)
Output Frequency (Max) (MHz)
Normalized PLL Phase Noise (dBc/Hz)
VCO Phase Noise (Nom) (dBc/Hz)
1/f Noise (10 kHz offset at 1 GHz carrier) (dBc/Hz)
Current Consumption (mA)
VCC (V)
Integrated VCO
Pin/Package
LMX2581E LMX2571 LMX2581 LMX2582 LMX2592
50    10    50    20    20   
3800    1344    3760    5500    9800   
-229    -231    -229    -231    -231   
-121    -115    -121    -129    -129   
-125    -124    -125    -126    -126   
178    39    178    250    250   
3.15 to 3.45    3.15 to 5    3.15 to 3.45    3.15 to 3.45    3.15 to 3.45   
Yes    Yes    Yes    Yes    Yes   
32WQFN      32WQFN    40VQFN    40VQFN   

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