LTC6945 - Ultralow Noise and Spurious 0.35GHz to 6GHz Integer-N Synthesizer

The LTC®6945 is a high performance, low noise, 6GHz phaselocked loop (PLL), including a reference divider, phasefrequency detector (PFD) with phase-lock indicator, charge pump, integer feedback divider and VCO output divider.

The part features a buffered, programmable VCO output divider with a range of 1 through 6. The differential, low noise output buffer has user-programmable output power ranging from –6dBm to 3dBm, and may be muted through either a digital input pin or software.

The low noise reference buffer outputs a typical 0dBm square wave directly into a 50Ω impedance from 10MHz to 250MHz, or may be disabled through software.

The ultralow noise charge pump contains selectable high and low voltage clamps useful for VCO monitoring, and also may be set to provide a V+/2 bias.

All device settings are controlled through a SPI-compatible serial port.

  • Low Noise Integer-N PLL
  • 350MHz to 6GHz VCO Input Range
  • –226dBc/Hz Normalized In-Band Phase Noise Floor
  • –274dBc/Hz Normalized In-Band 1/f Noise
  • –157dBc/Hz Wideband Output Phase Noise Floor
  • Excellent Spurious Performance
  • Output Divider (1 to 6, 50% Duty Cycle)
  • Low Noise Reference Buffer
  • Output Buffer Muting
  • Charge Pump Supply from 3.15V to 5.25V
  • Charge Pump Current from 250μA to 11.2mA
  • Configurable Status Output
  • SPI Compatible Serial Port Control
  • PLLWizard Software Design Tool Support
Typical Application
LTC6945 Typical Application
LTC6945 Typical Application
LTC6945 Package Drawing
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LTC6945IUFD#PBF4x5 QFN-28I$7.07$4.95
LTC6945IUFD#TRPBF4x5 QFN-28I$5.01
Demo Boards
Part NumberDescriptionPrice
DC1649A-ALTC6945 Demo | Ultralow Noise and Spurious 6GHz Integer-N Synthesizer, VCO=902-928Hz, (Req DC590)$125.00
Companion Boards
Part NumberDescriptionPrice
DC2026CLinduino One Isolated USB Demo Board: An Arduino- and QuikEval-Compatible Code Development Platform$75.00
DC2429ALT3042 PLL/VCO Supply and Reference Board$150.00
DC590BIsolated USB Serial Controller for Linear Technology QuikEval-Compatible Demo Boards$50.00
Application Note
Reliability Data
Product Selector Card
Press Release
Software and Simulation
CAD Symbol
Related Products
LTC6945 - Ultralow Noise and Spurious 0.35GHz to 6GHz Integer-N Synthesizer
一种准确地预测由泄漏电流引起的 PLL 基准杂散噪声之简单方法
超低噪声和杂散、350MHz 至 6GHz、整数 N PLL / 合成器抑制系统噪声
AN143 - A Simple Method to Accurately Predict PLL Reference Spur Levels Due to Leakage Current
R565 - Reliability Data
Ultralow Noise Synthesizers
Ultralow Noise & Spurious 350MHz to 6GHz Integer-N PLL/Synthesizer Suppresses System Noise
LTC6945 - IBIS Model
LTC6945 Footprints and Symbols
LTC6945 - DC1649A.INO
LTC6945 - Linduino Header File
LTC6945 - Linduino.CPP File