LINEAR 2PB_6946fa Ultralow Noise Synthesizers User Manual
Summary
Designed for demanding RF engineers, these ultralow noise frequency synthesizers deliver superior phase noise and spectral purity across a wide range (350MHz–6GHz). The comprehensive manual details the architecture, operational parameters, and integrated features of the PLL-based circuitry. It provides full support through the robust PLLWizard CAD tool, enabling users to precisely simulate, optimize, and ensure stable performance for optimal hardware design.
Page 1 Text Content
Ultralow Noise Synthesizers LTC6946 REF OSC VCO
Output
Divider
Low Noise and Spurious Levels, 350MHz to 6GHz Frequency Synthesizers Our new ultralow noise, integer-N frequency synthesizers provide best-in-class phase noise and spurious performance. The LTC®6946 is a complete frequency synthesizer that includes a high performance, low noise, 5.7GHz phase-locked loop (PLL) with a fully integrated, low phase noise VCO. The LTC6945 separates the low 1/f corner PLL core for use with an external VCO up to 6GHz. The free, easy-to-use PLLWizard™ CAD tool quickly and accurately simulates synthesizer performance to ensure an optimal design.
Features LTC6946-3 PLL Phase Noise
IS c/ z)
n 350MHz to 6GHz VCO Input Range (LTC6945) –80
n Low –226d Bc/Hz Normalized In-Band Phase Noise Floor
n –157d Bc/Hz Wideband Output Phase Noise Floor
n Industry’s Lowest –274d Bc/Hz Normalized In-Band 1/f Noise
n Spurious Levels < –100d Bc –110
n High Current 11m A Output Charge Pump Minimizes Loop
Compensation Thermal Noise
n Programmable Output Divider for Wide Operating Frequency Range
RMS NOISE = 0.61°
n 28-Pin (4mm × 5mm) QFN Packages
–140P RMS JITTER = 296fs f RF = 5.7GHz –150 f PFD = 10MHz Frequency Coverage Options BW = 85k Hz –160
LTC6946-1 LTC6946-2 LTC6946-3
OFFSET FREQUENCY (Hz)
VCO Frequency (GHz) 2.240 to 3.740 3.080 to 4.910 3.840 to 5.790
OUT DIV = 1 2.240 to 3.740 3.080 to 4.910 3.840 to 5.790
OUT DIV = 2 1.120 to 1.870 1.540 to 2.455 1.920 to 2.895
OUT DIV = 3 0.747 to 1.247 1.027 to 1.637 1.280 to 1.930
OUT DIV = 4 0.560 to 0.935 0.770 to 1.228 0.960 to 1.448
OUT DIV = 5 0.448 to 0.748 0.616 to 0.982 0.768 to 1.158
OUT DIV = 6 0.373 to 0.623 0.513 to 0.818 0.640 to 0.965
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PLLWizard is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Page Summary Contents For LINEAR 2PB_6946fa Ultralow Noise Synthesizers User Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 2 |
| File Size | 275.82 KB |
| Published | June 17, 2026 |
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Frequently Asked Questions
What tool can I use to simulate synthesizer performance before design?
The free, easy-to-use PLLWizard™ CAD tool allows you to quickly and accurately simulate performance.
How do I select a desired output frequency range?
You can use the Programmable Output Divider which is settable to integers from 1 to 6, or choose different dedicated models (e.g., LTC6946-X).
What are the reported normalized in-band phase noise and spurious levels for the LTC6946-3?
Specifications include a Normalized In-Band Phase Noise Floor of –226dBc/Hz, Industry’s Lowest Normalized In-Band 1/f Noise at –274dBc/Hz, and Spurious Levels less than –100dBc.
What is the reference clock input range for this PLL?
The relevant REF INPUT voltage range is between 10MHz and 250MHz.