Load-mismatch sensitivity of class-E power amplifiers

Ali Ghahremani, Anne-Johan Annema, Bram Nauta

    Research output: Contribution to journalArticleAcademicpeer-review

    7 Citations (Scopus)
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    Class-E RF power amplifiers (PAs) are very power efficient under nominal operating conditions. Due to incorporating two tuned tanks, the dependence on the load impedance is, however, relatively large, resulting in, e.g., load-dependent output power, power efficiency, peak voltages, and peak (and average) currents which can lead to reliability issues. This paper presents load-pull analyses for class-E RF PAs from a mathematical perspective, with analyses and discussions of the effects of the most common nonidealities of class-E PAs: the limited loaded quality factor (Qloaded) of the series filter, switch on-resistance, the limited quality factor of the dc-feed inductor, load mismatch-dependent switch conduction loss, and the limited negative voltage excursions (due to, e.g., the reverse conduction of the switch transistor for negative voltage excursions). The theoretical findings are backed up by extensive circuit simulations and load-pull measurements of a class-E PA implemented in 65-nm CMOS technology. The PA provides 18.1-dBm output power and 72% efficiency at 1.4 GHz under nominal operating condition employing an off-chip matching network.
    Original languageEnglish
    Article number8500354
    Pages (from-to)216-230
    Number of pages15
    JournalIEEE transactions on microwave theory and techniques
    Issue number1
    Publication statusPublished - 1 Jan 2019


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