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 kt2 of their constituent resonators and iii) low loss passbands with high-effective quality factor (Qeff) > 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 Qeff > 5300, FBW as high as 0.9 kt2, and minimal IL of 3 dB.