Film bulk acoustic wave resonator technology

Abstract

It is demonstrated that completely monolithic two-pole filters can be fabricated on silicon substrates using FBARs (film bulk acoustic resonators) and that these filters have low loss and reasonable bandwidth. A two-pole monolithic ladder filter operating in the 1-1.5 GHz range has been demonstrated. These filters (0.3*0.3*0.02 in) have a bandwidth of 30 MHz at 1 GHz and an insertion loss of about 1 dB. The small size serves to provide good shock and acceleration tolerance. Preliminary results on a stacked FBAR filter operated in high overtone mode show response up to 5.5 GHz. The authors review the development of FBAR technology, including piezoelectric film and membrane materials, fabrication techniques, temperature compensation schemes, and the progress made in processing monolithic filters. Issues relating to integration of FBARs with active circuits and IC processing compatibility are addressed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>