Fabrication of a Low insertion loss intrinsically switchable BAW filter based on BST FBARs

A Low insertion loss (IL) 1.5 stage H'-network ladder type intrinsically switchable bulk acoustic wave (BAW) filter based on barium strontium titanate (Ba
₀
.
₅
Sr
₀
.
₅
TiO
₃
) thin film bulk acoustic resonators (FBARs) is presented. The filter is designed and fabricated based on switchable BST FBARs with Q
_m
=300 and K
_t
²
=6%. When a DC bias is applied to the FBARs, the switchable filter is in its ON state and provides an insertion loss of 2.25 dB with 3-dB bandwidth of 58 MHz at 2.08 GHz center frequency. The switchable BST filter presented in this paper provides the lowest IL as compared to the previously reported BST filters.