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). This paper will review the SCF and expand on the basic concepts of the CRF. Experimental results will be shown for SCFs operating to 12 GHz and CRFs near 3 GHz. Manufacturing issues associated with both filter types will be reviewed with greater emphasis on the CRF.