Multiconfigurable Acoustic-Wave-Lumped-Resonator (AWLR)-Based Bandpass-to-Bandstop Filters With Continuously Tunable Characteristics

Multiconfigurable and continuously tunable acoustic-wave resonator (AWR)-based filters exhibiting bandpass (BP) and bandstop (BS) responses with continuously tunable center frequency (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{\mathrm {cen}}$</tex-math> </inline-formula>) and bandwidth (BW) alongside an all-pass (AP) and an all-stop (AS) mode of operation are reported in this work for the first time. They are based on multiresonant, multiconfigurable acoustic-wave-lumped-resonator stages. Each stage comprises one high-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> surface acoustic wave (SAW) resonator and three low-<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> lumped element (LE) resonators and simultaneously supports: 1) a BP mode with tunable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{\mathrm {cen}}$</tex-math> </inline-formula> and BW, shaped by one pole and two transmission zeros (TZs); 2) a BS mode with tunable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{\mathrm {cen}}$</tex-math> </inline-formula> and BW, shaped by one TZ and two reflection zeros (RZs); 3) an AP state; and 4) an AS state. By cascading <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> acoustic-wave-lumped-element resonator (AWLR) stages, a highly selective quasi-elliptic BP transfer function (TF) with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> poles and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2~{N}$</tex-math> </inline-formula> TZs, and a BS TF with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> TZs and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2~{N}$</tex-math> </inline-formula> RZs can be created having fractional BWs (FBWs) greater 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 the AWR. A novel switchless tuning mechanism is introduced to enable BP-to-BS reconfigurability without the need for RF switches for the first time. The operating principles are demonstrated through various synthesized coupling-matrix (CM) and circuit-simulated design examples. This concept is experimentally validated at 916.4 MHz through single-, two-, and three-stage prototypes, demonstrating continuous <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${f} _{\mathrm {cen}}$</tex-math> </inline-formula> and FBW tuning with BP/BS/AP/AS reconfigurability. The filters exhibit FBW between 0.3 and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.78~{k} _{t}^{2}$</tex-math> </inline-formula>, and insertion loss (IL) ranging from 0.9 to 5.8 dB, corresponding to effective <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i>-factors (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q} _{\mathrm {\mathrm { eff}}}$</tex-math> </inline-formula>) between 1900 and 5200.