Multiband Acoustic-Wave-Lumped-Element Resonator-Based Bandpass-to-Bandstop Filters

A new class of multiband acoustic-wave resonator-based RF filters with reconfigurable bandpass-to-bandstop (BP-to-BS) transfer function characteristics is reported. They are based on a hybrid integration scheme in which multiresonant acoustic-wave-lumped-element-resonators (AWLRs) are combined with five static and one switched impedance inverters. Each multiresonant AWLR controls the number of bands and their center frequencies. Switching between the bandpass and bandstop modes of operation is achieved by changing the coupling path between its input/output ports through an RF-switched impedance inverter. For practical validation purposes, two prototypes were designed, manufactured, and tested. They include a single-band BP-to-BS filter at 418 MHz and a dual-band BP-to-BS filter with bands centered at 418 and 433.9 MHz.