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


  • 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


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.


For complete and up to date package information and drawings, please refer to our packaging page


LTC6945 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC6945IUFD#PBF QFN 28 I $7.07 $4.95 View
LTC6945IUFD#TRPBF QFN 28 I $5.01 View
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1649A-A LTC6945 Demo | Ultralow Noise and Spurious 6GHz Integer-N Synthesizer, VCO=902-928Hz, (Req DC590) $125.00
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Companion Boards

Part Number Description Price Documentation
DC1216A-D 100MHz PLL Synthesizer Reference Clock Source $150.00
DC590B USB Serial Controller for Linear Technology QuikEval Demo Boards $50.00
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Click here to view our complete list of demo boards


  • Wireless Base Stations (LTE, WiMAX, W-CDMA, PCS)
  • Broadband Wireless Access
  • Microwave Data Links
  • Military and Secure Radio
  • Test and Measurement

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Design Tools


Linear Technology PLLWizard is used to communicate with the LTC6945 and LTC6946 synthesizers. It uses the DC590 controller to translate between USB and SPI-compatible serial communications formats. It also includes advanced PLL design and simulation capabilities. You may use it to:

  • Recommend part parameters based on your frequency plan
  • Design noise-optimized loop filters
  • Simulate loop frequency response and stability
  • Simulate VCO and Reference source noise
  • Simulate output noise characterisics and statistics

Click here to download PLLWizard Software Design Tool

Technical Support