High-tone bulk acoustic resonator integrated with surface micromachined FBAR filter on a single chip

This paper describes a novel high-tone bulk acoustic resonator (HBAR) integrated with a surface micromachined FBAR (film bulk acoustic resonator) filter on sapphire substrate. The single-mode HBAR exhibited a loaded quality factor (Q/sub loaded/) of 3,580 at 2.5 GHz with a total size (including the contact pads) of 0.8/spl times/0.4/spl times/0.4mm/sup 3/. The integrated narrow band FBAR filter provides adequate suppression (>4dB) of the unwanted modes in the HBAR. This high Q and small size resonator is ideally suited for Pierce oscillator for voltage controlled oscillator (VCO) above 2 GHz.