Single-chip multi-frequency wideband filters based on aluminum nitride cross-sectional Lamé mode resonators with thick and apodized electrodes

This work reports on three monolithic integrated contiguous 3
^rd
-order ladder filters formed by high-k
_t
²
Aluminum Nitride (AlN) Cross-Sectional Lamé Mode resonators (CLMRs). The three devices operate around 1 GHz and show a record-high 3 dB fractional bandwidth (FBW > 3.9%) and unprecedented low levels of insertion loss (IL <; 1 dB) and ripples. Such features are enabled by the combined use of CLMRs adopting thick platinum electrodes and having apodized interdigitated metal electrodes (IDTs).