  Wireless communication through dynamic spectrum allocation over microwave
bands, essential to accommodate exponentially growing data traffic, requires
massive array of radio-frequency (RF) filters for adaptive signal shaping at
arbitrary frequencies. However, conventional RF filters based on planar
acoustic resonators are incapable to realize such massive integrated arrays,
due to their large footprint and limited on-chip frequency scalability. Here,
we present a signal processor enabled by integration of three-dimensional
ferroelectric-gate fin (FGF) nano-acoustic resonators with extreme frequency
tailorability and large-scale integrability. FGFs are created by growing
atomic-layered ferroelectric hafnia-zirconia transducers on silicon nano-fins,
operate in bulk acoustic modes with lithographically scalable frequency over
3-28 GHz, and provide record high frequency - quality factor -
electromechanical coupling product (f.Q.kt2) of 19.4 x 1010 (at ~11GHz). A
monolithic filter-array covering 9-12 GHz is also demonstrated by on-chip
electrical coupling of FGFs. This demonstration highlights the potential of FGF
resonators to realize chip-scale adaptive processors extendable to
millimeter-wave frequencies.
