Class-F GaN HEMT amplifiers using compact CRLH harmonic tuning stubs designed based on negative order resonance modes

Shinichi Tanaka, Sota Koizumi, Ishikawa, Kazuhiko Honjo

Research output: Contribution to journalArticle


Extremely compact harmonic tuning circuits for class-F amplifiers are realized using composite right-/left-handed (CRLH) transmission line stubs. The proposed circuits take up only a small fraction of the amplifier circuit area and yet are capable of treating four harmonics up to the 5th with a single stub or double stub configuration. This has become possible by using the negative order resonance modes of the CRLH TL, allowing for flexible and simultaneous control of many harmonics by engineering the dispersion relation of the stub line. The CRLH harmonic tuning stubs for 2-GHz amplifiers were realized using surface mounting chip capacitors, whereas the stub for 4-GHz amplifiers was fabricated based fully on microstrip-line technology. The fabricated 2-GHz and 4-GHz GaN HEMT class-F amplifiers exhibited peak drain efficiency and peak PAE of more than 83% and 74%, respectively.

Original languageEnglish
Pages (from-to)691-698
Number of pages8
JournalIEICE Transactions on Electronics
Issue number10
Publication statusPublished - 2019 Jan 1



  • Left-handed metamaterials,
  • Power amplifier

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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