Reconfigurable Acoustic-Wave-Resonator-Based RF Filtering Architectures for Next Generation Wireless Communications

Acoustic-wave-resonator (AWR)-based RF filters have been the core filtering technology of cellular RF transceivers with more than fifty filtering devices currently being present in an ordinary smartphone. Emerging wireless communications (beyond 5G) are expected to require an even larger number of filters (> 100) in their RF front-ends able to support wider operational bandwidths, multiple bands as well as being adaptive to the spectrum/user needs. Current SAW- and BAW-based technologies exhibit narrow fractional bandwidth (constrained by the electromechanical coefficient kt2 to 0.4-0.8kt2) and static transfer functions. Furthermore, they are only able to realize a certain types of transfer functions (quasi-elliptic bandpass) due to their poles and transmission zeros being constrained by the kt2. Considering the aforementioned limitations, this webinar will introduce a new concept to realize AWR filters with advanced functionality using hybrid acoustic-wave-lumped-element resonators (AWLRs. The AWLR concept allows for filters with: i) enhanced FBW (>kt2), ii) small physical size, iii) high-Q (1,000-10,000), iv) arbitrary transfer functions and iv) tunable responses. The webinar will present the fundamental foundations of the AWRL concept through circuit analysis followed by coupled-resonator-based synthesis. Various AWLR-based filtering topologies will be illustrated in terms of RF design, synthesis (coupling matrix approach) and experimental performance with a major focus on bandpass- and bandstop-type responses. Afterwards, we will discuss advanced multi-band architectures as well as filters with reflectionless passband and stopband characteristics. Novel AWR filter concepts with flat and negative group delay will also be presented. Lastly, we will introduce unique tuning concepts leading to transfer functions with multiple levels of RF tuning namely bandwidth, out-of-band isolation, all pass and all-stop responses.