Analysis and elimination of hysteresis and noisy precursors in power amplifiers

Sanggeun Jeon, Almudena Suárez, David B. Rutledge

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


Power amplifiers (PAs) often exhibit instabilities leading to frequency division by two or oscillations at incommensurate frequencies. This undesired behavior can be detected through a large-signal stability analysis of the solution. However, other commonly observed phenomena are still difficult to predict and eliminate. In this paper, the anomalous behavior observed in a Class-E PA is analyzed in detail. It involves hysteresis in the power-transfer curve, oscillation, and noisy precursors. The precursors are pronounced bumps in the power spectrum due to noise amplification under a small stability margin. The correction of the amplifier performance has required the development of a new technique for the elimination of the hysteresis. Instead of a trial-and-error procedure, this technique, of general application to circuit design, makes use of bifurcation concepts to suppress the hysteresis phenomenon through a single simulation on harmonic-balance software. Another objective has been the investigation of the circuit characteristics that make the noisy precursors observable in practical circuits and a technique has been derived for their elimination from the amplifier output spectrum. All the different techniques have been experimentally validated.

Original languageEnglish
Pages (from-to)1096-1106
Number of pages11
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number3
Publication statusPublished - 2006 Mar
Externally publishedYes


  • Bifurcation
  • Class-E amplifier
  • Hysteresis
  • Noisy precursor
  • Stability
  • Synchronization

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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