Bulk acoustic wave coupled resonator filters

Coupled resonator filters (CRF) are a new form of bulk acoustic wave device that involves the vertical stacking of resonators. In that regard, the CRF can be thought of as a variation on the better known stacked crystal filter (SCF). However, the CRF is actually somewhat more analogous to the monolithic crystal filter (MCF) that was a mainstay in filters for low frequency applications. This paper reviews coupled resonator concepts, briefly including the MCF, describes the design and modeling of CRFs, and presents representative experimental results.