Global stability analysis and stabilization of a class-E/F amplifier with a distributed active transformer

Sanggeun Jeon, Almudena Suárez, David B. Rutledge

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


Power amplifiers (PAs) often exhibit instabilities giving rise to frequency divisions or spurious oscillations. The prediction of these instabilities requires a large-signal stability analysis of the circuit. In this paper, oscillations, hysteresis, and chaotic solutions, experimentally encountered in a high-efficiency class-E/F odd PA with four transistors combined using a distributed active transformer, are studied through the use of stability and bifurcation analysis tools. The tools have enabled an in-depth comprehension of the different phenomena, which have been observed in simulation with good agreement with experimental results. The study of the mechanism generating the instability has led to a simplified equivalent circuit from which the optimum stabilization network has been determined. The network enables a global stabilization of the circuit for all the expected operating values of the amplifier bias voltage and input power. This has been achieved with negligible degradation of the amplifier performance in terms of drain efficiency and output power. The stable behavior obtained in simulation has been experimentally confirmed.

Original languageEnglish
Pages (from-to)3712-3722
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number12
Publication statusPublished - 2005 Dec
Externally publishedYes

Bibliographical note

Funding Information:
Manuscript received February 22, 2005; revised May 5, 2005. This work was supported by the Lee Center for Advanced Networking and by the Jet Propulsion Laboratory. S. Jeon and D. B. Rutledge are with the Department of Electrical Engineering, California Institute of Technology, Pasadena, CA 91125 USA (e-mail: sjeon@; A. Suárez is with the Communications Engineering Department, University of Cantabria, 39005 Santander, Spain (e-mail: Digital Object Identifier 10.1109/TMTT.2005.856083


  • Bifurcation
  • Chaos
  • Distributed active transformer (DAT)
  • Hysteresis
  • Stability analysis
  • Stabilization
  • Switching amplifiers

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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