Single-to-Multi-Band Reconfigurable Acoustic-Wave-Lumped-Resonator Bandpass Filters
Kunchen Zhao, Dimitra Psychogiou
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${N}$ </tex-math></inline-formula> AWLR stages and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N+1$ </tex-math></inline-formula> impedance inverters. The proposed filter concept enables the realization of high order transfer functions with: i) reconfigurable number of bands between 1-to- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula> , ii) enhanced fractional bandwidth (FBW) that is wider than the electromechanical coupling coefficient <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{t}^{2}$ </tex-math></inline-formula> of their constituent resonators and iii) low loss passbands with high-effective quality factor ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q_{eff}$ </tex-math></inline-formula> ) > 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q_{eff} >$ </tex-math></inline-formula> 5300, FBW as high as 0.9 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{t}^{2}$ </tex-math></inline-formula> , and minimal IL of 3 dB.