Foundations and Trends® in Integrated Circuits and Systems > Vol 4 > Issue 2

CMOS LC Voltage-Controlled Oscillators: A Survey

By Bruno Barajas, Synopsys, Canada and University of British Columbia, Canada | Reza Molavi, University of British Columbia, Canada and Google, USA | Shahriar Mirabbasi, University of British Columbia, Canada, shahriar@ece.ubc.ca

 
Suggested Citation
Bruno Barajas, Reza Molavi and Shahriar Mirabbasi (2025), "CMOS LC Voltage-Controlled Oscillators: A Survey", Foundations and TrendsĀ® in Integrated Circuits and Systems: Vol. 4: No. 2, pp 115-209. http://dx.doi.org/10.1561/3500000021

Publication Date: 17 Nov 2025
© 2025 B. Barajas et al.
 
Subjects
Circuit level design,  Analog design,  Analog circuits and systems,  Circuit theory,  CMOS technology,  Emerging technologies,  Mixed-signal circuits and systems,  mm-Wave integrated circuits,  RF circuits
 
Keywords
LCVoltage-controlled oscillator (VCO)HarmonicPhase noiseMulti-standardInjection-locked oscillator (ILO)Multi-phase oscillator
 

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In this article:
1. Introduction
2. Fundamentals of LC VCOs
3. Phase Noise
4. Popular Classes of LC VCOs
5. Advanced LC VCO Topologies
6. Injection-locked Oscillators
7. Multi-phase LC VCOs
8. Emerging THz Signal and Pulse Generators
9. Concluding Remarks
References

Abstract

LC oscillators are among the key building blocks in modern electronic systems, and their design and performance are continuously advancing. This report provides a comprehensive review of research and development trends in CMOS LC oscillator design over the past two decades. We first review the principles governing LC oscillator operation and go over their key performance metrics such as phase noise and frequency tuning range. Then various classes of voltage-controlled oscillators (VCOs) are overviewed, highlighting their distinct characteristics and applications. Furthermore, advanced oscillator topologies designed to improve tuning range, power efficiency, and phase noise are explored. To extend the discussion on oscillator architectures, the concept of injection locking and the implementation of injection-locked oscillators (ILOs) are analyzed. Additionally, common design challenges and trade-offs associated with the presented topologies are discussed. The review concludes with an examination of recent advancements in oscillators operating in the terahertz (THz) frequency range, emphasizing the critical role of LC oscillators in such applications.

DOI:10.1561/3500000021
ISBN: 978-1-63828-625-7
108 pp. $160.00
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Table of contents:
1. Introduction
2. Fundamentals of LC VCOs
3. Phase Noise
4. Popular Classes of LC VCOs
5. Advanced LC VCO Topologies
6. Injection-locked Oscillators
7. Multi-phase LC VCOs
8. Emerging THz Signal and Pulse Generators
9. Concluding Remarks
References

CMOS LC Voltage-Controlled Oscillators: A Survey

The ever-increasing demand for high-speed data communication mandates the generation and distribution of a clean high-speed clock. Due to their intrinsic suppression of out-of-band noise, LC oscillators have become the heart of many such advanced clocking systems. Over the past few decades, researchers from industry and academia have been exploring different avenues to enhance the performance of these oscillators in terms of their power consumption, phase noise, maximum operational frequency, frequency tuning range, and various figures-of-merit (FoMs).

LC oscillators are among the key building blocks in modern electronic systems, and their design and performance are continuously advancing. This monograph provides a comprehensive review of research and development trends in CMOS LC oscillator design over the past two decades. First reviewed are the principles governing LC oscillator operation and go over their key performance metrics such as phase noise and frequency tuning range. Then, various classes of voltage-controlled oscillators (VCOs) are overviewed, highlighting their distinct characteristics and applications. Furthermore, advanced oscillator topologies designed to improve tuning range, power efficiency, and phase noise are explored. To extend the discussion on oscillator architectures, the concept of injection locking and the implementation of injection-locked oscillators (ILOs) are analyzed. Additionally, common design challenges and trade-offs associated with the presented topologies are discussed. The monograph concludes with an examination of recent advancements in oscillators operating in the terahertz (THz) frequency range, emphasizing the critical role of LC oscillators in such applications.

 
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