Shear Mode Polarity Inverted ScAlN Multilayer for Application to BAW Transformer in Rectifying Antenna

Sarina Kinoshita, Takahiko Yanagitani

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Energy harvesting from surrounding environment is required for battery-less sensors. RF-DC conversion with a rectifying antenna (so-called rectenna) is generally used to obtain energy from ambient electromagnetic wave. However, RF-DC conversion efficiency of the diode significantly decreases for ambient electromagnetic wave due to their weak RF power. In this study, we report a new type of bulk acoustic wave (BAW) piezoelectric transformer based on c-axis zig-zag multilayers ScAlN film in order to amplify the RF signal in the rectenna. c-Axis approximately 45°-tilted film exhibit high k'152 without undesired longitudinal wave excitation. The theoretical voltage gain was simulated by Mason's equivalent circuit model considering polarization inversions due to c-axis zig-zag structures. Voltage gain increase with k2Q value (= FOM) increasing or the number of layers n in the output layer increasing. S parameters of a BAW piezoelectric transformer with c-axis zig-zag 4 layers ScAlN film are measured by a network analyzer. As a result, voltage gain approaching + 20 dB with the 4 layers BAW piezoelectric transformer is obtained. This new type of polarization inverted FBAR transformer is attractive for a voltage transformer in the rectenna.

Original languageEnglish
Title of host publication2019 IEEE International Ultrasonics Symposium, IUS 2019
PublisherIEEE Computer Society
Pages1118-1119
Number of pages2
ISBN (Electronic)9781728145969
DOIs
Publication statusPublished - 2019 Oct
Event2019 IEEE International Ultrasonics Symposium, IUS 2019 - Glasgow, United Kingdom
Duration: 2019 Oct 62019 Oct 9

Publication series

NameIEEE International Ultrasonics Symposium, IUS
Volume2019-October
ISSN (Print)1948-5719
ISSN (Electronic)1948-5727

Conference

Conference2019 IEEE International Ultrasonics Symposium, IUS 2019
CountryUnited Kingdom
CityGlasgow
Period19/10/619/10/9

Keywords

  • BAW
  • rectenna
  • ScAlN
  • transformer

ASJC Scopus subject areas

  • Acoustics and Ultrasonics

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    Kinoshita, S., & Yanagitani, T. (2019). Shear Mode Polarity Inverted ScAlN Multilayer for Application to BAW Transformer in Rectifying Antenna. In 2019 IEEE International Ultrasonics Symposium, IUS 2019 (pp. 1118-1119). [8925674] (IEEE International Ultrasonics Symposium, IUS; Vol. 2019-October). IEEE Computer Society. https://doi.org/10.1109/ULTSYM.2019.8925674