Single-to-Multi-Band Reconfigurable Acoustic-Wave-Lumped-Resonator Bandpass Filters

A new class of single-to-multi-band reconfigurable acoustic-wave-lumped-resonator (AWLR)-based bandpass filters (BPFs) is reported. They are based on K in-parallel cascaded switchable bandpass channels. Each channel is shaped by
${N}$
AWLR stages and
$N+1$
impedance inverters. The proposed filter concept enables the realization of high order transfer functions with: i) reconfigurable number of bands between 1-to-
${K}$
, ii) enhanced fractional bandwidth (FBW) that is wider than the electromechanical coupling coefficient
$k_{t}^{2}$
of their constituent resonators and iii) low loss passbands with high-effective quality factor (
$Q_{eff}$
) > 5,000. For proof-of-concept validation, an AWLR BPF with 1-to-3 reconfigurable bands was designed, manufactured, and tested at UHF band. It exhibited three passbands centered at 1000 MHz, 1010 MHz and 1040 MHz with
$Q_{eff} >$
5300, FBW as high as 0.9
$k_{t}^{2}$
, and minimal IL of 3 dB.