Designing LC VCOs using capacitive degeneration techniques

Byunghoo Jung, Ramesh Harjani

Research output: Chapter in Book/Report/Conference proceedingChapter


In this paper, we present a detailed analysis of VCOs using a capacitively degenerated negative resistance cell. The negative resistance cell using capacitive degeneration has a higher maximum attainable oscillation frequency and a smaller equivalent shunt capacitance when compared to the widely used cross-coupled negative-gm cell. These properties are of particular interest for the design of high-frequency and/or wide tuning range VCOs. The negative resistance provided by a traditional capacitively degenerated negative resistance cell is lower than that provided by a cross-coupled negative-gm cell. We present an active capacitive degeneration topology that overcomes this limitation. To validate this circuit topology we use two test vehicles. The first test vehicle is a 5.3 GHz VCO designed in a 0.25 µm CMOS technology and the second test vehicle is a 20 GHz VCO designed in a 0.25 µm BiCMOS technology. Measurement and simulation results from both test vehicles effectively demonstrate the efficacy of the capacitive degeneration technique.

Original languageEnglish (US)
Title of host publicationDesign Of High-speed Communication Circuits
PublisherWorld Scientific Publishing Co.
Number of pages33
ISBN (Electronic)9789812774583
StatePublished - Jan 1 2006

Bibliographical note

Publisher Copyright:
© 2006 by World Scientific Publishing Co. Pte. Ltd.


  • Analog integrated circuits
  • BiCMOS integrated circuits
  • Capacitive degeneration
  • High-frequency LC oscillators
  • Negative resistance cell
  • Voltage-controlled oscillators


Dive into the research topics of 'Designing LC VCOs using capacitive degeneration techniques'. Together they form a unique fingerprint.

Cite this