TY - GEN
T1 - Shear Mode Polarity Inverted ScAlN Multilayer for Application to BAW Transformer in Rectifying Antenna
AU - Kinoshita, Sarina
AU - Yanagitani, Takahiko
N1 - Funding Information:
ACKNOWLEDGMENT This work was supported by the JST PRESTO (No. JPMJPR16R8) and KAKENHI (Grant-in-Aid for Scientific Research No.16H04356, No.19H02202, and No.18K19037).
Publisher Copyright:
© 2019 IEEE.
PY - 2019/10
Y1 - 2019/10
N2 - 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.
AB - 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.
KW - BAW
KW - ScAlN
KW - rectenna
KW - transformer
UR - http://www.scopus.com/inward/record.url?scp=85077587516&partnerID=8YFLogxK
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U2 - 10.1109/ULTSYM.2019.8926197
DO - 10.1109/ULTSYM.2019.8926197
M3 - Conference contribution
AN - SCOPUS:85077587516
T3 - IEEE International Ultrasonics Symposium, IUS
SP - 847
EP - 848
BT - 2019 IEEE International Ultrasonics Symposium, IUS 2019
PB - IEEE Computer Society
T2 - 2019 IEEE International Ultrasonics Symposium, IUS 2019
Y2 - 6 October 2019 through 9 October 2019
ER -