High rejection UNII 5.2GHz wideband bulk acoustic wave filters using undoped single crystal AlN-on-SiC resonators

Abstract

5.24GHz bulk acoustic wave filters, utilizing undoped single crystal aluminum nitride, are reported. The filters had an absolute 4dB bandwidth of 151 MHz, a minimum insertion loss of 2.82 dB and rejection >38 dB. Resonators show k <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> of 6.32%, Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rnax</sub> of 1523, and FOM of 96.